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Cementless knee arthroplasty: a review of recent performance

Authors:
  • Imperial School of Orthopaedics

Abstract

Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes. Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty. This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice. Cite this article: Bone Jt Open 2021;2(1):48–57.
VOL. 2, NO. 1, JANUARY 2021 48
Freely available online
Follow us @BoneJointOpen
BJO
A. Asokan,
R. Plastow,
B. Kayani,
G. T. Radhakrishnan,
A. A. Magan,
F. S. Haddad
From University College
Hospital, London,
United Kingdom
Correspondence should be sent to
Mr Ajay Asokan; email:
ajay. asokan@ nhs. net
doi: 10.1302/2633-1462.21.BJO-
2020-0172.R1
Bone Jt Open 2021;2-1:48–57.
KNEE
Cementless knee arthroplasty: a review
of recentperformance
Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual
advantages, including improved osseointegration providing biological fixation, increased
surgical eciency, and reduced systemic complications associated with cement impaction
and wear from cement debris. Increasingly younger and higher demand patients are re-
quiring knee arthroplasty, and as such, there is optimism cementless fixation may improve
implant survivorship and functional outcomes.
Compared to cemented implants, the National Joint Registry (NJR) currently reports higher
revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental
knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes
with cementless implants, particularly with UKA which has shown superior performance to
cemented varieties. Cementless TKA has yet to show long- term benefit, and currently per-
forms equivalently to cemented in short- to medium- term cohort studies. However, with
novel concepts including 3D- printed coatings, robotic- assisted surgery, radiostereometric
analysis, and kinematic or functional knee alignment principles, it is hoped they may help
improve the outcomes of cementless TKA in the long- term. In addition, though cementless
implant costs remain higher due to novel implant coatings, it is speculated cost- eectiveness
can be achieved through greater surgical eciency and potential reduction in revision costs.
There is paucity of level one data on long- term outcomes between fixation methods and the
cost- eectiveness of modern cementless knee arthroplasty.
This review explores recent literature on cementless knee arthroplasty, with regards to clin-
ical outcomes, implant survivorship, complications, and cost- eectiveness; providing a con-
cise update to assist clinicians on implant choice.
Cite this article: Bone Jt Open 2021;2-1:48–57.
Keywords: Cementless, Uncemented, Knee Arthroplasty, Total Knee Arthroplasty, Unicompartmental Knee Arthroplasty, Knee Replacement
Introduction
Knee arthroplasty is the preferred treatment
of end- stage osteoarthritis (OA) with over
99,000 performed annually in the UK.1 This
includes approximately 90,000 total knee
arthroplasties (TKAs) and 9,000 unicom-
partmental knee arthroplasties (UKAs) per
year. The fixation method can vary between
cemented, cementless, and hybrid implant
systems. Cemented implants remain the
most commonly used components for
TKA, making up 86% of all primary knee
arthroplasties in the UK.1 Cemented TKAs
have well- established long- term functional
outcomes and excellent survivorship, with
greater than 95% implant survivorship at
minimum ten years follow- up.1-3 However,
multiple registries report higher rates of revi-
sion in younger patients secondary to aseptic
loosening, which has led to surgeons seeking
better osseointegration and biological fixa-
tion to improve implant survivorship.4,5
Cementless implant fixation in knee
arthroplasty oers a number of conceptual
benefits including: improved component
fixation through direct osseointegration with
the implant coatings, better preservation of
the native bone stock, improved surgical e-
ciency and reduced systemic complications
associated with cement impaction and debris
wear.4,6 Cementless implants have also been
shown to reduce the prevalence of radio-
logical radiolucent lines (RLL), which may
help to improve implant survivorship and
reduce revision rates compared to cemented
implants for UKA and TKA.7 These advan-
tages have led to a number of high- volume
centres selecting cementless over cemented
VOL. 2, NO. 1, JANUARY 2021
CEMENTLESS KNEE ARTHROPLASTY: A REVIEW OF RECENT PERFORMANCE 49
UKA,1,8 with excellent patient- reported outcomes and
implant survivorship of over 97% at minimum ten years
follow- up.9,10 Over the last decade, evolution of implant
design and materials have enabled TKA to follow a similar
trend to UKA.
Critics of cementless implants for TKA and UKA cite
potentially increased periprosthetic fracture rates,11
femoral component fracture rates,12 increased risk
of aseptic loosening in the tibial component,13 and
reduced long- term implant survival rates compared to
their cemented counterparts.14,15 However, these studies
were based on early implant designs, with rudimentary
implant materials and limited contouring of implants to
match the native osseous architecture. Recent advances
in implant design, component materials and opera-
tive techniques, have improved implant survivorship
compared to their predecessors, achieving ten- to 15- year
survivorship of 96% to 100%.16-18
This comprehensive review provides an update on
recent outcomes following cementless knee arthroplasty,
primarily evaluating functional outcomes and implant
survivorship; with additional evaluation of complications,
novel technologies and alignment principles, and overall
cost- eectiveness of cementless knee arthroplasty.
Methods
A comprehensive literature search was performed
between the years 2000 and 2020 across three electronic
databases – PubMed, Embase, and MEDLINE. Included
search terms were: (total knee arthroplasty OR arthro-
plasty) AND (unicompartmental knee arthroplasty OR
arthroplasty) AND (cementless OR uncemented). Bibliog-
raphies of relevant articles were searched for additional
studies. Eligibility criteria included: 1) patients under-
going primary total or unicompartmental knee arthro-
plasty; 2) cementless implants; 3) reported outcomes
including functional outcomes, and/or implant survivor-
ship, and/or complications, and/or cost analysis. Studies
not in the English language or without full text availability
were excluded, as were studies before 2000 as they
reported on previous generation cementless implants. All
studies were divided between UKA and TKA, and outlined
in TablesI and II, respectively.
UKA outcomes
Functional outcomes. UKA has proven to be an excel-
lent procedure in both cemented and cementless var-
iants, with superior functional outcomes to TKA.26–28
Advantages include shorter surgical time, reduced blood
loss, retention of soft tissue structures, preservation of
bone stock, and retention of native knee kinematics.28–33
A large body of the literature on UKA surrounds a
mobile bearing unicompartmental implant, reported
to have consistently excellent functional outcomes with
cementless fixation.8–10,28,29,34–36 Recently, Mohammad
et al37 reported their prospective results at ten- year
follow- up of 1,000 cementless mobile bearing UKA.
They used Oxford Knee Scores (OKS), Tegner Activity
Scores, and American Knee Society Scores (Objective
(KSS- O) and Functional (KSS- F)) to measure functional
outcomes. At ten years, their mean OKS was 41.2, Tegner
2.8, KSS- O 89.1, and KSS- F 80.4, which were all signifi-
cantly better to mean preoperative scores (p < 0.0001).
Similar results were shown by Campi et al,10 who report
seven- year results, on their prospective study analyzing
functional outcomes of 1,000 consecutive cementless
UKAs performed at two high- volume centres. They used
the same mobile bearing unicompartmental implant as
above. Their mean OKS improved from 23.2 preopera-
tively to 42.7 at seven years (p < 0.001). Similar excellent
mid- to long- term results are shown in a number of other
recent studies on cementless UKA.9,38,39
There are limited studies comparing outcomes directly
between cemented and cementless UKA. However,
Pandit et al40 performed a prospective study of 1,000
cemented UKA at ten- year follow- up, in a similar study
to Mohammad et al,37 with both studies performed at
the same centre. They used the cemented version of
the same mobile bearing unicompartmental implant,
through a minimally invasive approach, and measured
the same functional outcomes. At ten years, their mean
OKS was 40, Tegner 2.7, KSS- O 80, KSS- F 76, and mean
flexion angle 127o. They report 55% of patients having
excellent outcomes (OKS > 41), and 10% having poor
outcomes (OKS < 27). Both studies were very similar, and
although lower functional outcome scores were found in
the cemented UKA study, there is no statistical analysis
between these two.
Cementless UKA may also be associated with faster
return to activities. Panzram et al41 recently studied
return to sports and level of activity following cement-
less UKA in a retrospective series of 228 UKA, with
follow- up at two years in their independent, high-
volume centre. In this series, 92.9% of all patients
returned to sport, and of these, 64% within the first
three months postoperatively.
Several National Joint Registries (NJRs) have shown
UKA to have higher revision rates to TKA in both cemented
and cementless forms.1-3 The same registries, however,
have shown some cementless UKA to perform signifi-
cantly better than cemented with regards to implant
survivorship, citing progression of OA as the leading
cause for revision in both fixation systems. Some studies
have suggested cementless fixation is better suited for
UKA,35,42 specifically through restoration of normal liga-
ment tension with minimal implant constraint, which
restores native kinematics producing compressive forces
across components. These minimize the sheer forces at
the implant- bone interface, thus reducing aseptic loos-
ening and failure.35
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50
Table I. Summarised characteristics of UKA studies.
Study Year Implant Study design
Mean age,
yrs
Number of knees,
cementless
cemented Outcomes Main findings Survivorship
Mean
follow-
up, yrs
Horvath et al19 2020 HA- cementless
vs cementless vs
cemented
Meta- analysis 55.7 to 72.6 N/R N/R MTPM, KSS HA significantly lower MPTM
than cementless, but greater
than cemented.
No dierence in KSS.
N/R N/A
Toksvig- Larsen et al20 2020 3D- printed
cementless vs
cemented
Prospective
cohort
Cementless
65,
cemented 66
35 34 MTPM, KSS Greater migration in Cementless
in first three months.
No dierence in migration
between groups after three
months.
N/R 2
Chen et al21 2019 Cementless vs
cemented
Meta- analysis 51 to 61 229 255 KSS, ROM,
pain score,
RLL, aseptic
loosening
KSS: N/S
ROM: N/S
Pain: improved in cementless.
RLL: Improved in cementless.
Aseptic loosening: N/S.
N/R 2 to
13.6
Fricka et al22 2019 Cementless vs
cemented
RCT Cemented
58.4,
cementless
59.8
41 44 KSS, OKS,
VAS, RLL,
KSS cemented 92.7.
KSS cementless 89.3.
OKS cemented 44.8
OKS Cementless 44.0
95.9%
cemented,
95.3%
cementless.
5
Dunbar et al23 2019 Cementless and
cemented
Prospective
Cohort
62 21 58 MTPM Significant correlation between
one and two years migration
with long- term migration.
No dierence in long- term
migration between cementless
and cemented.
Inducible displacement
significantly higher in Cemented
components.
N/R 2 and
12
Moric et al24 2019 Cementless - 3D-
printed coating
Prospective
Cohort
64 29 MTPM, KSS,
KOOS, EQ- 5D
Rate of migration largest over
first six weeks postoperatively.
No migration after six months.
All PROM measurements showed
significant improvement at final
F/U.
N/R 2
Zhou et al16 2018 Cementless vs
cemented
Meta- Analysis 54.3 to 73 409 403 KSS, MTPM,
WOMAC,
ROM,RLL
No statistically significant
dierence across all outcomes
No statistically
significant
dierence.
7.1
Kim et al25 2013 Cement less vs
cemented
Prospective
cohort
4 80 80 KSS,
WOMAC,
ROM, RLL
No significant dierence across
all outcome measures.
98.7% in
cementless tibial
component.
100% in
all other
components.
16.6
EQ- 5D, Euro- Qol five- dimension index; F/U, follow- up; HA , hydroxyapatite; KOOS, Knee Injury and Osteoarthritis Outcome Score; KSS, Knee Society Score (Objective, Functional); MTPM,
maximum total point motion; N/A, not applicable; N/R, not reported; N/S, not significant; OKS, Oxford Knee Score; PROM, patient- reported outcome measure; RCT, randomized controlled
trial; RLL, radiolucent lines; ROM, range of movement; RTS, return to sport; UCLA, University of California, Los Angles Activit y Score; VAS, visual analogue scale; WOMAC, Western Ontario and
McMaster Universities Osteoarthritis Index.
The aforementioned study by Campi et al10 prospec-
tively reviewed 1,000 cementless UKA performed in two
high- volume centres, and reported ten- year survivor-
ship. When defining failure as revision for any cause, they
report ten- year survivorship at 96.8% (95% confidence
interval (CI) 93.1 to 100). Whereas using component
failure (loosening, wear, component fracture) as the end-
point, only one patient required revision producing a
ten- year survivorship of 99.9%. Of the 25 (2.5%) patients
who required revision, the most common cause was
progression of lateral OA, in line with registry data. This
is currently the largest published prospective study on
cementless UKA, with extremely low incidence of failure
from loosening, suggesting cementless UKA may have
excellent osseointegration.
Mohammad et al9 undertook a pooled analysis of 8,760
cemented and 1,946 cementless UKAs, and reported ten-
year survivorship was 92.7% and 95.5%, respectively (p
< 0.001). The authors reported improved revision rates
in cementless mobile- bearing UKAs relative to cemented,
but consistent revision rates among fixed- bearing UKAs
regardless of cementation group. Similarly, Parratte et
al43 reviewed outcomes in 5,325 UKA (mobile- and fixed-
bearing) for medial compartment OA and found overall
component survivorship was 95% at ten- year follow- up.
Van der List et al42 reviewed outcomes from a series of
prospective cohort studies, including 2,218 cementless
UKA and reported extrapolated component survivorship
at five, ten, and 15 years was 96.4%, 92.9%, and 89.3%,
respectively. In 10,309 cementless TKAs, these values
were 97.7%, 95.4%, and 93%, respectively.
Although a similar trend to registry data is reported,
there are clear discrepancies between them and the
higher reported survivorship in large cohort studies. This
eect has been noted by several studies10,37,40,42 , and is
hypothesized to be attributed to cohort studies often
being performed at high- volume centres, which has a
known positive influence on outcomes.44–46 Registry data
does not dierentiate between high- and low- volume
surgeons. Nevertheless, there is an overall positive trend
VOL. 2, NO. 1, JANUARY 2021
CEMENTLESS KNEE ARTHROPLASTY: A REVIEW OF RECENT PERFORMANCE 51
Table II. Summarized characteristics of total knee arthroplasty studies.
Study Year Implant Study design
Mean age,
yrs
Number of knees,
cementless
cemented Outcomes Main findings Survivorship
Mean
follow-
up, yrs
Horvath et al19 2020
HA- cementless
vs cementless vs
cemented Meta- analysis
55.7 to
72.6 N/R N/R MTPM, KSS
HA significantly lower MPTM
than cementless, but greater than
cemented. No dierence in KSS. N/R N/A
Toksvig- Larsen
et al20 2020
3D- printed
cementless vs
cemented
Prospective
cohort
Cementless
65,
cemented
66 35 34 MTPM, KSS
Greater migration in Cementless in
first three months. No dierence in
migration between groups after three
months. N/R 2
Chen et al21 2019
Cementless vs
cemented Meta- analysis 51 to 61 229 255
KSS, ROM,
pain score,
RLL, aseptic
loosening
KSS: N/S.
ROM: N/S.
Pain: Improved in cementless.
RLL: Improved in cementless.
Aseptic loosening: N/S. N/R 2 to 13.6
Fricka et al22 2019
Cementless vs
cemented RCT
58.4
cemented,
59.8
cementless 41 44
KSS, OKS,
VAS, RLL,
KSS cemented 92.7.
KSS cementless 89.3.
OKS cemented 44.8.
OKS cementless 44.0.
95.9%
cemented,
95.3%
cementless. 5
Dunbar et al23 2019
Cementless and
cemented
Prospective
cohort 62 21 58 MTPM
Significant correlation between
one and two years migration with
long- term migration. No dierence
in long- term migration between
cementless and cemented. Inducible
displacement significantly higher in
cemented components. N/R 2 and 12
Moric et al24 2019
Cementless - 3D-
printed coating
Prospective
cohort 64 29
MTPM, KSS,
KOOS, EQ- 5D
Rate of migration largest over
first six weeks postoperatively. No
migration after six months. All PROM
measurements showed significant
improvement at final F/U. N/R 2
Zhou et al16 2018
Cementless vs
cemented Meta- analysis 54.3 to 73 409 403
KSS, MTPM,
WOMAC,
ROM,RLL
No statistically significant dierence
across all outcomes.
No statistically
significant
dierence. 7.1
Kim et al25 2013
Cementless vs
cemented
Prospective
cohort 4 80 80
KSS,
WOMAC,
ROM, RLL
No significant dierence across all
outcome measures.
98.7% in
cementless
tibial
component.
100% in
all other
components. 16.6
EQ- 5D, Euro- Qol five- dimension index; F/U, follow- up; HA , hydroxyapatite; KOOS, Knee Injury and Osteoarthritis Outcome Score; KSS, Knee Society Score (Objective, Functional); MTPM,
maximum total point motion; N/R, not reported; N/S, not significant; OKS, Oxford Knee Score; PROM, patient- reported outcome measure; RCT, randomized controlled trial; RLL, radiolucent
lines; ROM, range of movement; RTS, return to sport; UCLA, University of California, Los Angles Activity Score; VAS, visual analogue scale; WOMAC, Western Ontario and McMaster Universities
Osteoarthritis Index.
of improved implant survivorship in cementless UKA rela-
tive to their cemented counterparts.
TKA outcomes
Functional outcomes. Unlike UKA, there is great paucity
of prospective studies evaluating recent cementless TKA
outcomes. Chen and Li21 performed a meta- analysis of
six randomized controlled trials (RCTs)25,47–51 compar-
ing cemented and cementless TKA in younger patients
(aged ≤ 60 years), focusing on functional outcomes.
There were 255 cemented, and 229 cementless pros-
theses with mean follow- up between two to ten years.
They concluded cementless TKA to be vastly superior in
pain scores and radiological outcomes (defined by the
presence of RLLs), but performed equally to cemented
TKA in functional outcome, range of movement, and
aseptic loosening. Specifically, a significant improvement
in pain with weighted mean dierence (WMD) in pain
score (visual analogue scale) of 3.029 (95% CI 5.119 to
0.939, p = 0.005). Additionally, cementless fixation was
found to have KSS of equivalent or better (WMD -0.239;
95% CI -2.154 to -1.676; p = 0.807), and less incidence of
aseptic loosening (RD -0.001; 95% CI -0.030 to 0.028; p
= 0.946), relative to cemented.
Fricka et al22 performed an RCT with five- year
follow- up between 50 cementless (cementless femur CR
flex design with a fibre metal mesh ingrowth surface and
a cementless modular trabecular metal pegged tibia tray)
and 50 cemented TKA (cemented precoat CR flex femur
and a cemented precoat keeled tibia tray), both groups
receiving the same polyethylene liner, resurfaced patella,
surgical approach, and rehabilitation protocol. They
found equivalent results between the two groups at five
years when measuring KSS, OKS, and pain scores. The
scores were: KSS 92.7 ± 12.5 in cemented, and 89.3 ±
14.2 in cementless (p = 0.14); OKS 44.8 ± 3.5 cemented,
44.0 ± 3.8 cementless (p = 0.33); and visual analogue
scale (VAS) pain score at four months 1.6 ± 2.0 cemented,
2.1 ± 1.8 cementless (p = 0.06).
Horvath et al19 performed a meta- analysis of RCTs
comparing specifically hydroxyapatite (HA) coated
TKAs against other cementless and cemented implants.
They concluded HA- coating provides better stability as
measured by the maximum total point motion (MTPM)
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52
of the tibial stem, assessed by radiostereometric anal-
ysis (RSA), in comparison to non- HA coated cementless
implants (WMD = 0.28 mm, 95% CI 0.01 to 0.56, p =
0.045), but has worse stability than cemented fixation
(WMD = -0.29, 95% CI -0.41 to 0.16, p < 0.001). Their
secondary outcome measures were functional outcome
assessed through KSS. They found the KSS of HA- coated
cementless prostheses were not significantly dierent to
other cementless implants (WMD = -0.64, 95% CI -3.02–
1.73, p = 0.596), and similarly, there was no statistically
significant dierence between KSS of HA- coated and
cemented implants (WMD = -0.29, 95% CI -2.27 to 1.69,
p = 0.775).
The functional outcome data of cementless over
cemented UKA is firmly established, with data in cement-
less TKA improving. Mid- term results show equivalent
outcomes between cemented and cementless TKA,
however there is a paucity of high- quality RCT data
assessing long- term functional outcomes.
Implant survivorship. Traditionally, cementless TKA have
exhibited worse implant survivorship than cemented
equivalents; however, newer prostheses in the last dec-
ade have set to improve upon this. At present, both the
UK and Australian NJRs report higher revision rates in ce-
mentless TKA over cemented.1,3 However, in the Australian
NJR, they do note if a posterior stabilized implant is used,
cemented implants have lower revision rates in the first
2.5 years, but after 4.5 years cementless implants dis-
play lower revision rates. As previously discussed in UKA,
there continues to be discrepancies in outcomes between
registry data and cohort studies, attributed to the amal-
gamation of high- and low- volume centre outcomes for
cementless TKA.44,46
At present, recent literature suggests cementless TKA
performs equivalently to cemented TKA. Zhou et al16
performed a meta- analysis, which analyzed the survivor-
ship between 409 cementless TKAs and 403 cemented
TKAs with a range of follow- up between two and 17 years.
The RCTs were published between 1998 and 2014. They
found no significant dierence in survivorship between
cemented and cementless TKA at a mean follow- up of 7.1
years (p = 0.25).
Fundamentally, cemented TKA remains the preferred
choice of implant with a long history of good results.15,52
However, increasing interest in cementless TKA surrounds
the higher rates of failure in cemented TKA found in
younger, obese and active patients.48,53–56 The UK NJR
shows the ten- year survivorship across all types of knee
arthroplasty is worse with younger age: 89% in age < 55
years, 94% in age 55 to 64 years, 96% in age 65 to 74
years, and 98% in age ≥ 75 years.57 The mechanism in
these patients is said to arise from increased sheer forces
and stress at the bone- cement interface, thus leading
to micromotion and aseptic loosening or osteolysis.
The principle of cementless fixation relies on biological
fixation through excellent ingrowth of bone into the
surface of the implant.58 Salem et al17 concluded through
their analysis of a number of cohort studies, cementless
TKA is a viable treatment option in a variety of patient
demographics including those: < 60 or > 75 years of age,
were obese, had rheumatoid arthritis, or had osteone-
crosis of the knee.
Kim et al25 performed a prospective, randomized trial
comparing cemented and cementless TKA in patients
aged under 55 year. They performed simultaneous bilat-
eral TKA in 80 patients (160 knees), with cemented fixa-
tion in one limb, and cementless in the other. Their mean
age at operation was 54.3 years, and mean follow- up
was 16.6 years. All procedures were performed by their
senior author, with the same technique, anaesthetic, and
rehab. They reported a 100% survival of both cemented
and cementless femoral components, with one cement-
less tibial component requiring revision at one year post-
operative due to aseptic loosening, meaning a 98.7%
survival of the cementless tibial components. This study
showed equivalent survivorship of cementless TKA with
cemented in young patients.
With a lack of long- term high quality evidence in
the literature, radiostereometric analysis represents an
excellent surrogate for long- term migration and thus
survivorship. Dunbar et al23 studied the level of tibial
component migration between 58 cemented, and 21
cementless TKAs, using RSA. They compared RSA results
at one to two years, to those ten years later with mean
follow- up of 12 years (10 to 14). Their measurement vari-
able was MTPM, used to record both static and inducible
tibial component migration (loaded single- leg stance).
They report significant correlation between one to two
year RSA findings with ≥ ten- year follow- up findings
(p < 0.001), with strongest correlation at two years for
cementless components. Median overall migration at
long- term follow- up was the same in both groups (0.6
mm, p = 0.99). However, inducible displacement at ten
years was significantly higher for cemented components
(p < 0.001), which leads to their conclusion of cement-
less fixation in TKA to oer equal if not superior long-
term results to cemented. In addition, they outline two
dierent migration patterns; cemented showing progres-
sive migration over the long- term, whereas cementless
fixation migrates the most in the first two years, but then
stabilizes.
More recently, Toksvig- Larsen’s group20 performed a
similar RCT using RSA between 36 cemented TKA and
36 novel 3D- printed cementless TKA. They compared
mean MTPM at three, 12, and 24 months with results of
0.33 mm, 0.42 mm, and 0.47 mm, respectively in the
cemented group, versus 0.52 mm, 0.62 mm, and 0.64
mm, respectively in the cementless group (p = 0.003).
However, if three month results were used as baseline,
they found no dierence in mean migration between the
VOL. 2, NO. 1, JANUARY 2021
CEMENTLESS KNEE ARTHROPLASTY: A REVIEW OF RECENT PERFORMANCE 53
two groups (p = 0.497). Their conclusion parallels that of
Dunbar et al,23 in which cementless TKA show increased
migration in the initial three months, which then stabi-
lises. Other novel 3D- printed implants have shown similar
results; Moric et al24 in their prospective cohort study of
29 cementless TKAs with highly porous tibial baseplates,
report largest tibial migration in the first six weeks post-
operatively, but nil after six months. Parallel results have
been shown in cemented implants with RSA studies
reporting cemented TKA migrate less in the initial three
months, but continue up to and beyond one year, which
may be the reason for failure in younger patients.48,59 The
literature shows good evidence that cementless implants
exhibit increased rates of migration in the short- term (up
to one year), but stabilize thereafter.47,60,61
Fundamentally, although a number of encouraging
recent studies suggest conceptual improvements in
performance through reduced migration, and some
cohort studies suggest equivalent survivorship; cement-
less TKA has yet to be proven to have better survivorship
relative to cemented TKA in the long- term through level
1 studies or indeed the NJR. Unlike cementless UKA, there
are insucient high- quality prospective cohort studies
comparing outcomes between fixation methods, and this
would be a primary area of further research.
Complications
In UKA, aseptic loosening and progression of OA are
the two most common forms of complications, quoted
at 36% and 20%, respectively.62 However, specifically in
cementless UKA, progression of lateral OA followed by
dislocation are reported to be the most common compli-
cations, with notably reduced incidence of aseptic loos-
ening.10 Similar results are shown by Blaney et al who
report no incidence of aseptic loosening in their series
of 238 cementless mobile- bearing UKA at five- year
follow- up.63
A risk of intraoperative fracture is a worry in all cement-
less arthroplasty, but is noted to be a rare complication,
with a low incidence of 0.003% reported by Liddle et
al11 in their multicentre series of 1,000 cementless UKA.
They note two risk factors: extended sagittal saw cuts, or
breach of the posterior cortex upon tibial preparation,
both of which would be reduced by higher volumes.
The positive eect of high volume centres is well
noted, Mohammad et al’s64 analysis of the UK NJR
reports low- volume surgeons had a higher revision rate
in both cemented and cementless UKA (p < 0.001), with
higher volumes showing ten- year survivorship of 97.5%,
comparable to the best- performing TKAs. Additionally,
they show cementless fixation decreases revision rate by
25%, regardless of volume (p = 0.002). Robotic- assisted
surgery may be an avenue to increase reproducibility to
allow low- volume UKA centres to achieve similar results
to high- volume centres.65
Cementless TKA exhibit a slightly dierent failure- mode
profile to cementless UKA. In a series of 244 cementless
TKA, Van Der List et al42 report 25% of failures due to
aseptic loosening, with infection (16%) and instability
(9%) the second and third most common. Cemented TKA
show a similar failure profile, but with higher incidence of
aseptic loosening at 31%.66
Interest in cementless TKA has increased due to
higher demand patients suering increased failure rates
from aseptic loosening in cemented TKA. Bagsby et al55
demonstrate in their multicentre series of 292 morbidly
obese patients (143 cementless vs 149 cemented),
cementless TKAs have significantly lower revision rates
compared to cemented TKA (0.7% vs 13%, p < 0.001),
with the most common cause in cemented (5.8%, nine
knees) secondary to aseptic loosening, and no incidence
of this in the cementless group (p = 0.005). Whiteside
and Vigano67 concur in their study comparing 122 young,
overweight patients with 122 older but normal weight
patients. They report equivalent KSS and survivorship
at a minimum of 5 years follow- up (p < 0.03), between
cementless and cemented TKA, concluding cementless
TKA is safe in young, overweight patients.
Prosthetic joint infection (PJI) is a major complication,
and has been investigated to see if cementless arthro-
plasty can reduce the rates due to less operating time, as
increased operating time is a known risk factor for infec-
tion. Anis et al68 in their case- control study of 3,180 TKA
which underwent matched (age, sex, body mass index,
Charlson comorbidity index) analysis of 133 cementless
TKA and 132 cemented TKA, found cementless TKA to
take 17 minutes less (98 ± 26 vs 115 ± 37 minutes, p <
0.001), and no significant dierence in infection rate (PJI
and superficial surgical infection) between cemented and
cementless TKA at two years follow- up.68 Equally, Onggo
et al found largely equivalent results between cemented,
cementless and hybrid fixation in their meta- analysis of
12 RCTs (1,573 knees) looking solely at infection rates.
They report on 926 knees from studies evaluating
cemented versus cementless, and 646 knees from studies
evaluating cemented vs hybrid. The mean follow- up was
10.25 years across all 12 RCTs. They conclude the infec-
tion rate was lowest among cemented TKA relative to
cementless TKA (odds ratio (OR) 0.90, 95% CI 0.35 to
2.28). However, the rate of PJI requiring revision surgery
was lowest in cementless TKA as compared to cemented
(OR 0.89, 95% CI 0.30 to 2.41).
With aseptic loosening being the most common
cause of failure in TKA, research moving forward should
focus on minimizing this. In part, cementless tech-
niques seek to solve this, but novel technologies with
implant coatings and robotics will look to improve this
further.
BONE & JOINT OPEN
A. ASOKAN, R. PLASTOW, B. KAYANI, G. T. RADHAKRISHNAN, A. A. MAGAN, F. S. HADDAD
54
Alignment and robotics
Both functional alignment and robotic- assisted surgery
are evolving concepts in knee arthroplasty, which have
potential to improve clinical outcomes.
Functional alignment aims to reproduce a patient’s
natural kinematics to theoretically improve functional
outcomes and survivorship.69-71 Within cementless knee
arthroplasty, functional alignment may improve cortico-
cancellous contact of the tibial component, thus reducing
subsidence of the tibial component. This subsidence
into varus or valgus has been reported by a number of
studies.22,72,73 Moran et al74 reported a 19% failure rate
at mean 64- month follow- up in a series of cementless
total knee arthroplasties. They concluded that surgeons
needed to maximize the tibial corticocancellous contact
with the tibial component to reduce micromotion,
subsidence and increase the area for ingrowth.
Arguably a principle cause for poor outcomes in
cementless knee arthroplasty is poor surgical technique,
due to the finer margins involved relative to cemented
knee arthroplasty.37, 6 4 This in part has allowed robotic-
assisted arthroplasty to evolve and aim to equalize the
gap between high- and low- volume surgeons. Studies
have shown benefits in the short- to medium- term, of
the ecacy of robotic- assisted TKA in improving both
functional outcomes and survivorship,75 in addition to
causing less periarticular soft tissue trauma,76 reduced
postoperative pain, decreased analgesia requirements,
and increased knee flexion at discharge.77 The reduced
soft tissue trauma may lead to faster recovery thus
improving surgical eciency. In addition, the Austra-
lian NJR reports robotic- assisted UKA have lower revision
rates compared to manual UKA, and has been shown to
reduce loosening, progression of disease and pain, but
does increase revisions for infection3
Both concepts display promising results to date, and
conceptually are well suited to cemented knee arthro-
plasty, although the lack of high- quality prospective trials
does not allow for direct recommendation at present.
However, this is an exciting area for future research,
which should focus on RCT data comparing func-
tional alignment and robotic- assisted surgery with their
counterparts.
Cost-eectiveness
Traditionally, cementless implant design has proved
more costly due to manufacturing costs of novel coat-
ings applied to ensure osseointegration. However, recent
studies have analyzed the overall costs including oper-
ating time, implant costs, cement and cement accessory
costs to assess the true cost dierence.
Lawrie et al’s78 recent RCT reviewed the cost dierences
between cemented and cementless TKA. They compared
67 cemented and 80 cementless TKAs, analyzing oper-
ative time (cost of $36/minute), implant costs, cement,
and cement accessories. They report although cement-
less implants cost on average $366 more than cemented,
the total costs of cementation in addition to implant
costs were $588 to $1,043, which outweighs the addi-
tional cementless implant costs. A similar outcome was
reported by Yayac et al, who retrospectively analyzed
itemised costs in 2307 cemented TKA and 119 cementless
TKA. They report although cementless implant costs were
higher ($3,047 vs $2,808); cementless TKA was associ-
ated with lower total costs ($5,921 vs $6,111). This was
due to shorter operative time, lower supply costs, and
no cement costs.79 It is worth noting that the incremental
time savings through not cementing over the course of
an arthroplasty list may provide enough time to perform
extra procedures.
A large retrospective analysis of the National Inpatient
Sample database by Gwam et al80 have found opposing
results to the above. They reviewed 167,930 TKA
(4,870 cementless vs 163,060 cemented), with primary
outcomes of complications, length of stay, and inpatient
costs. They report cementless TKA to have higher inpa-
tient costs ($17,357 vs $16,888) and charges ($67,366 vs
$64,190), but shorter inpatient stay with higher odds of
being discharged to home. The authors concluded the
higher charges may be secondary to patient selection, as
they were used in younger, more active patients, predom-
inantly under private insurance over public funding.
Overall, a holistic approach to costings must be
taken. Although implant costs are greater in cementless,
particularly with the advent of novel technologies, the
overall procedural costs are lower. With greater uptake
of the technology, inevitable economies of scale will
follow, allowing further cost- savings. The benefits of
surgical eciency with cementless knee arthroplasty is
clear; however, there is a lack of research evaluating the
potential outpatient savings and reduced revision costs
associated with cementless arthroplasty in appropriate
patients, which would be an area for further research.
Fundamentally, one must not use cost alone as a barrier
to cementless TKA, as confirmed by studies in other
healthcare economies.78,79,81,82
Conclusion
Recent studies of cementless knee arthroplasty are begin-
ning to encourage surgeons back to this technique. This
article shows that cementless TKA performs as well as
cemented in functional outcomes and survivorship,
particularly when used in high- demand groups, with
emerging evidence of superior performance. In cement-
less UKA, both functional outcomes and survivorship are
strongly outperforming cemented UKA.
Complication rates of cementless knee implants are
much improved upon their predecessors. New coatings
and surgical techniques are improving osseointegration,
thus reducing aseptic loosening risk. In addition, with
VOL. 2, NO. 1, JANUARY 2021
CEMENTLESS KNEE ARTHROPLASTY: A REVIEW OF RECENT PERFORMANCE 55
novel technologies such as 3D- printing and robotic-
assisted arthroplasty, we will hopefully see these
outcomes improve further.
At present, the cost of cementless implants remains
higher than cemented. Some studies have shown greater
overall cost eectiveness with cementless implants
through greater surgical eciency, and reduced periph-
eral costs. However, there is a lack of high- quality data
which evaluates long- term cost analysis, including
potentially reduced revision rates and better functional
outcomes.
There are a number of areas for further research, with
the literature primarily lacking in high- quality evidence
for long- term outcomes to clearly answer whether
cementless knee implants improve functional outcomes
and implant survivorship. There is greater paucity
surrounding outcomes in cementless TKA than UKA.
Greater long- term RCT evidence comparing both fixa-
tion methods is required to justify the use of cementless
knee arthroplasty. Additionally, analysis of the true cost-
eectiveness of cementless knee arthroplasty can only
occur once a holistic overview including survivorship and
revision rates are taken into account.
Take home message
- Cementless knee arthroplasty has shown promising results
in total knee arthroplasty (TKA) and unicompartmental
knee arthroplasty (UKA). However, long- term randomized
controlled trial evidence of cementless TKA is yet awaited.
- Cementless knee implants remain of higher cost, though cost-
effectiveness may be gained through potentially lower revision rates
and improved functional outcomes in the longer- term.
- Cementless knee implants are a viable choice in younger and high-
demand patient groups.
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VOL. 2, NO. 1, JANUARY 2021
CEMENTLESS KNEE ARTHROPLASTY: A REVIEW OF RECENT PERFORMANCE 57
Author contributions:
A Asokan: Devised, researched, wrote and edited the manuscript
R Plastow: Wrote and edited the manuscript
B Kayani: Prepared the manuscript.
G.T Radhakrishnan: Prepared the manuscript.
A.A Magan: Edited the manuscript.
F.S Haddad: Hypothesis generation, prepared manuscript.
Funding statement:
No benefits in any form have been received or will be received from a commercial
party related directly or indirectly to the subject of this article.
ICMJE COI statement:
F. S. Haddad reports editorial board membership by The Bone & Joint Journal and
the Annals of the Royal College Of Surgeons, consultancy and royalties from Smith
& Nephew, Corin, MatOrtho, and Stryker, and payment for lectures from Smith &
Nephew and Stryker, all of which are unrelated to this article.
© 2021 Author(s) et al. This is an open- access ar ticle distributed under the terms of
the Creative Commons Attribution Non- Commercial No Derivatives (CC BY- NC- ND 4.0)
licence, which permits the copying and redistribution of the work only, and provided
the original author and source are credited. See https:// creativecommons. org/ licenses/
by- nc- nd/ 4. 0/.
80. Gwam CU, George NE, Etcheson JI, Rosas S, Plate JF, Delanois RE. Cementless
versus Cemented fixation in total knee arthroplasty: usage, costs, and complications
during the inpatient period. J Knee Surg. 2019;32(11):1081–1087.
81. Haddad FS, Plastow R. Is it time to revisit cementless total knee arthroplasty? Bone
Joint J. 2020;102- B(8):965–966.
82. Kamath AF, Lee G- C, Sheth NP, Nelson CL, Garino JP, Israelite CL. Prospective
results of uncemented tantalum monoblock tibia in total knee arthroplasty:
minimum 5- year follow- up in patients younger than 55 years. J Arthroplasty.
2011;26(8):1390–1395.
Author information:
A. Asokan, MBBS, BSc (Hons), MRCS, Clinical Research Fellow
R. Plastow, FRCS (Orth), Senior Clinical Fellow
B. Kayani, MBBS, BSc (Hons), MRCS, Specialty Trauma & Orthopaedics Reigstrar
G. T. Radhakrishnan, MBBS, BSc (Hons), MRCS, Clinical Research Fellow
A. A. Magan, FRCS (Orth), Senior Clinical Fellow
F. S. Haddad, BSc, MD (Res), FRCS, Professor of Orthopaedic Surgery
Department of Trauma and Orthopaedic Surgery, University College Hospital,
London, UK; Department of Orthopaedic Surgery, The Princess Grace Hospital,
London, UK.
... Failure rates are two-fold higher for young patients 17 , who present a 35% revision risk in the 40-year follow-up upon cemented hip arthroplasties 18 . Implant technologies using uncemented fixations are thus significantly increasing worldwide 19 , particularly for younger and active patients whose lifestyle places heavy demands on implants 20 . Cementless fixations aim to maximize implant survival and outperform the mid-and long-term high deterioration risk of cemented implants 21,22 . ...
... Cementless fixations aim to maximize implant survival and outperform the mid-and long-term high deterioration risk of cemented implants 21,22 . Nevertheless, the risk of bone loss is higher due to stress-shielding using uncemented fixations, given the reduced mechanical stimuli delivered to peri-implant bone structures upon implant insertion 6,20,21 . Unstable bone-implant fixations triggered by stress-shielding can induce aseptic loosening, an adverse bone remodeling response that exceeds 50% of the revision indications 6,9,10,23 . ...
... This higher metabolism was not accompanied by increased proliferation, since Stim even slightly decreased the cells' DNA content (Fig. 5b, Stim vs Ctrl), similarly to what occurs when osteogenesis is induced in Ctrl cells (Fig. 5b, Ctrl BAS vs Ctrl OSTEO). The growth characteristics of hASCs differentiating under OSTEO medium at subsequent time points (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) were relatively similar between Stim and Ctrl conditions, with cells proliferating until 14-18 DIV (Fig. 5c, d). ...
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Replacement orthopedic surgeries are among the most common surgeries worldwide, but clinically used passive implants cannot prevent failure rates and inherent revision arthroplasties. Optimized non-instrumented implants, resorting to preclinically tested bioactive coatings, improve initial osseointegration but lack long-term personalized actuation on the bone–implant interface. Novel bioelectronic devices comprising biophysical stimulators and sensing systems are thus emerging, aiming for long-term control of peri-implant bone growth through biointerface monitoring. These acting-sensing dual systems require high frequency (HF) operations able to stimulate osteoinduction/osteoconduction, including matrix maturation and mineralization. A sensing-compatible capacitive stimulator of thin interdigitated electrodes and delivering an electrical 60 kHz HF stimulation, 30 min/day, is here shown to promote osteoconduction in pre-osteoblasts and osteoinduction in human adipose-derived mesenchymal stem cells (hASCs). HF stimulation through this capacitive interdigitated system had significant effects on osteoblasts’ collagen-I synthesis, matrix, and mineral deposition. A proteomic analysis of microvesicles released from electrically-stimulated osteoblasts revealed regulation of osteodifferentiation and mineralization-related proteins (e.g. Tgfb3, Ttyh3, Itih1, Aldh1a1). Proteomics data are available via ProteomeXchange with the identifier PXD028551. Further, under HF stimulation, hASCs exhibited higher osteogenic commitment and enhanced hydroxyapatite deposition. These promising osteoinductive/conductive capacitive stimulators will integrate novel bioelectronic implants able to monitor the bone–implant interface and deliver personalized stimulation to peri-implant tissues.
... 12,13) The popularity is also due to the fact that good osteointegration is obtained with porous coating and no additional time is required intraoperatively to ensure a lack of cement spillover. 14) Nevertheless, periprosthetic fractures are known to be more frequent in cementless surgery. 15,16) A couple of previous studies have compared staged and simultaneous bilateral UKA, but these studies have mainly focused on cemented implants. ...
... 5 A recent review evaluating the functional outcomes and implant survivorship with new generations of cementless TKAs has shown encouraging results for this type of fixation in primary TKA. 6 The authors also highlighted the importance of high-quality reporting of functional outcome and implant survivorship in the long term. To our knowledge, there are no other RSA studies with rTKAs, and therefore no data to act as reference when investigating the future effects of these patterns of migration. ...
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Aims: Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA). Methods: This is a follow-up of a randomized controlled trial, initially involving 32 patients, of whom 19 (nine cemented, ten hybrid) were available for follow-up ten years postoperatively, when further RSA measurements were made. Micromotion of the femoral and tibial components was assessed using model-based RSA software (RSAcore). The clinical outcome was evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), and visual analogue scale (pain and satisfaction). Results: The median total femoral translation and rotation at ten years were 0.39 mm (interquartile range (IQR) 0.20 to 0.54) and 0.59° (IQR 0.46° to 0.73°) for the cemented group and 0.70 mm (IQR 0.15 to 0.77) and 0.78° (IQR 0.47° to 1.43°) for the hybrid group. For the tibial components this was 0.38 mm (IQR 0.33 to 0.85) and 0.98° (IQR 0.38° to 1.34°) for the cemented group and 0.42 mm (IQR 0.30 to 0.52) and 0.72° (IQR 0.62° to 0.82°) for the hybrid group. None of these values were significantly different between the two groups and there were no significant differences between the clinical scores in the two groups at this time. There was only one re-revision, in the hybrid group, for infection and not for aseptic loosening. Conclusion: These results show good long-term fixation with no difference in micromotion and clinical outcome between fully cemented and hybrid fixation in rTKA, which builds on earlier short- to mid-term results. The patients all had type I or II osseous defects, which may in part explain the good results. Cite this article: Bone Joint J 2022;104-B(7):875-883.
... Many TKA factors may influence the tray-bone interface micromotion, such as surgical parameters, implant designs, and patient anatomy. However, since the cementless fixation in knee arthroplasty has become popular most recently (Aprato et al., 2016;Asokan et al., 2021), there is not much research investigating the cementless micromotion sensitivities to TKA factors. This section is dedicated to list the TKA factors studied in previous literature and outline their corresponding impact on the tray-bone interface micromotion. ...
Thesis
Full-text available
Cemented and cementless fixation in total knee arthroplasty (TKA) have been successfully used for decades. As the number of younger and more active patients treated with TKA continues to increase, long-term implant survivorship is of increasing importance. One of the most common complications and hence the reason for revision is mechanical loosening (23.1% of all revised TKA). The loosening mechanisms have been proposed for different fixation types. For cemented fixation, bone remodeling after surgery is regulated by the changes in strain energy density (SED). The recruitment of osteoclasts and osteoblasts is controlled by SED-related signals. Insufficient stimuli can promote bone resorption, which causes implant loosening. For cementless fixation, the initial fixation of cementless tibial trays is crucial to bony ingrowth onto the porous surface, as the micromotion magnitudes exceeding 150 µm may inhibit bone formations and cause implant loosening. However, the critical parameters influencing SED distributions and tray-bone micromotion are not fully understood. Finite element models have been commonly used to estimate the SED and micromotion, which typically cannot be measured experimentally. However, the challenge that has limited the use of computational modeling in clinical practice is model validation. Any poorly characterized input would directly influence the accuracy of the resulting outputs and cause validation failure. The purpose of this work is to create an experiment to finite element analysis pipeline for investigating the sensitivities of common TKA factors to the tibial SED and tray-bone micromotion. Specifically, the first study developed an experimental-computational validation framework for predicting tibial micromotion and bone deformation. The validated models were utilized for the subsequent application studies. The second study investigated the influence of five common TKA factors on tibial strain energy density. The third study assessed the impact of seven common TKA factors on the tray-bone interface micromotion. Physiological conditions were considered for both bone models and boundary conditions used in each study. Therefore, the conclusions were more clinically meaningful. There were clear recommendations for optimizing the post-operative SED distribution and minimizing the interface micromotion to improve the tibial fixation. The research framework presented in this dissertation could be used as a benchmark for investigating critical parameters influencing implant fixation stability. The computational models presented in this dissertation could be used for pre-clinical assessment and further implant development.
... Arthroplasty is the method of choice for the treatment of end-stage knee osteoarthritis (OA). In the UK, 90% of the procedures are performed as total knee arthroplasties (TKAs), and 86% of all primary knee arthroplasties are fixed with polymethylmethacrylate (PMMA) or bone cement [1]. Cemented TKAs with implant survivorship greater than 95% are regarded as the gold standard for patients undergoing knee replacement [2]. ...
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Porous tantalum has been extensively used in orthopaedic surgery, including uncemented total knee arthroplasty (TKA). Favourable results were reported with earlier monobloc tibial components and the design evolved to modular implants. We aimed to analyse possible causes for extensive medial tibia bone loss, resulting in modular porous tantalum tibia baseplate fracture after primary TKA. Retrieved tissue samples were scanned with 3 MeV focused proton beam for Proton-Induced X-ray Emission (micro-PIXE) elemental analysis. Fractographic and microstructural analysis were performed by stereomicroscopy. A full 3D finite-element model was made for numerical analysis of stress–strain conditions of the tibial baseplate. Histological examination of tissue underneath the broken part of the tibial baseplate revealed dark-stained metal debris, which was confirmed by micro-PIXE to consist of tantalum and titanium. Fractographic analysis and tensile testing showed that the failure of the tibial baseplate fulfilled the criteria of a typical fatigue fracture. Microstructural analysis of the contact surface revealed signs of bone ingrowth in 22.5% of the surface only and was even less pronounced in the medial half of the tibial baseplate. Further studies are needed to confirm the responsibility of metal debris for an increased bone absorption leading to catastrophic tibial tray failure.
... POD has long been acknowledged as a significant complication in surgery patients. With the aging of the population and the increase of joint diseases, the demand for joint replacement surgery is also increasing [16]. Studies have shown that the incidence of POD after major surgery is 20% to 50% in people over the age of 60 [17]. ...
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Objective: To explore the related risk factors of postoperative delirium (POD) after hip or knee arthroplasty in elderly orthopedic patients and the predictive value of related risk factors. Material and Methods. In total, 309 patients (≥60 years) who received knee and hip arthroplasty between January 2017 and May 2020 were consecutively selected into the POD and nonpostoperative delirium (NPOD) groups. Group bias was eliminated through propensity score matching. Univariate and multivariable logistic analysis was used to determine the risk factors for POD. The nomogram was made by R. Results: 58 patients were included in each group after propensity score matching; multivariable analysis demonstrated that LDH (OR = 4.364, P = 0.017), CHE (OR = 4.640, P = 0.004), Cystatin C (OR = 5.283, P = 0.006), arrhythmia (OR = 5.253, P = 0.002), and operation duration (OR = 1.017, P = 0.050) were independent risk factors of POD. LDH, CHE, Cystatin C, and arrhythmia were used to construct a nomogram to predict the POD. The nomogram was well calibrated and had moderate discriminative ability (AUC = 0.821, 95% CI: 0.760~0.883). Decision curve analysis demonstrated that the nomogram was clinically useful. Conclusions: Our study revealed that arrhythmia, operation duration, the increase of lactate dehydrogenase and Cystatin C, and the decrease of cholinesterase were reliable factors for predicting postoperative delirium after elderly hip and knee arthroplasty. Meanwhile, the nomogram we developed can assist the clinician to filtrate potential patients with postoperative delirium.
Article
Background Cementless total knee arthroplasty (TKA) is thought to facilitate durable, biological fixation between the bone and implant. However, the 4 to 12 weeks required for osseointegration coincides with the optimal timeframe to perform a manipulation under anesthesia (MUA) if a patient develops postoperative stiffness. This study aimed to determine the impact of early MUA on cementless fixation by comparing functional outcomes and survivorship of cementless and cemented TKAs. Methods A consecutive series of patients who underwent MUA for postoperative stiffness within 90 days of primary, unilateral TKA at two academic institutions between 2014 and 2018 were identified. Cases involving extensive hardware removal were excluded. Cementless TKAs undergoing MUA (n=100) were propensity matched 1:1 to cemented TKAs undergoing MUA (n=100) using age, sex, Body Mass Index (BMI) and year of surgery. Both groups had comparable baseline KOOS, SF-12 Physical, and SF-12 Mental scores. MUA-related complications as well as postoperative Knee Injury and Osteoarthritis Outcome Scores (KOOS) and Short Form (SF)-12 scores were compared. Results MUA-related complications were equivalently low in both groups (p=0.324), with only one patella component dissociation in the cementless group. No tibial or femoral components acutely loosened in the peri-operative period. Postoperative KOOS (p=0.101) and SF-12 Mental (p=0.380) were similar between groups. Six-year survivorship free from any revision after MUA was 98.0% in both goups (p=1.000). Conclusion Early postoperative MUA after cementless TKA was not associated with increased MUA-related complications or worse patient-reported outcomes compared to cemented TKA. Short-term survivorship was also comparable, suggesting high durability of the bone-implant interface.
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Background Higher Body Mass Index (BMI) has been associated with higher rates of aseptic loosening following cemented TKA. However, there is less known about the effect of BMI on the durability of modern cementless TKA. We aimed to assess the association between BMI and clinical outcomes following cementless TKA and to determine if there was a BMI threshold beyond which the risk of revision significantly increased. Methods We identified 1,408 cementless TKAs of a modern design from an institutional registry. Patients were classified into BMI categories: normal (n=136), overweight (n=476), obese class I (n=423), II (n=258), and III (n=115). KOOS-JR and SF-12 scores were collected preoperatively and 2 years postoperatively. Survivorship was recorded at minimum 2 years (range, 24 to 88 months). BMI was analyzed as a continuous and categorical variable. Results The improvement in patient-reported outcomes was similar across the groups. Thirty-four knees (2.4%) were revised, and 14 (1.0%) were for aseptic failure. Mean time-to-revision was 1.2±1.3 years and did not differ across BMI categories (p=0.455). Survivorship-free from all-cause and aseptic revision was 97.1 and 99.0% at mean 4 years, respectively. Using Cox regression to control for demographics and bilateral procedures, BMI had no association with all-cause revision (p=0.612) or aseptic revision (p=0.186). Receiver operating characteristic curve analysis found no relationship between BMI and revision risk (c-statistic=0.51). Conclusion BMI did not influence functional outcomes and survivorships of modern cementless TKA, possibly due to improved biological fixation at the bone-implant interface. Longer follow-up is necessary to confirm these findings.
Article
Background To report long-term survival and patient reported outcome measures (PROMs) of the uncemented Low Contact Stress (LCS) total knee system and explore the potential association between prior knee surgery and outcomes. Methods A total of 1289 procedures in 1068 patients performed between 2000 and 2010 (mean follow-up 11.1 years) were retrospectively identified. All patients received an uncemented, mobile bearing, anterior stabilized (cruciate sacrificing) knee implant with a porous coating on the bone-prosthesis surface. Implant survival was calculated using Competing Risk analyses at 5, 10 and 15 years. PROMs include the Oxford Knee Score, Knee Society Score (domain Function), EuroQol 5D-3L and Numeric Rating Scale for pain during rest and activity, and for overall satisfaction. The association between previous surgery (no surgery vs meniscectomy vs arthroscopy vs corrective osteotomies) and implant survival was assessed with multivariable Cox proportional hazards analysis, the association with PROMs was assessed with multivariable linear regression analyses. Results Survival after 5, 10 and 15 years was 97.0% (95% CI 96.0 – 98.0), 96.3% (95% CI 95.3 – 97.3) and 96.0% (95% CI 94.8 – 97.2), respectively. The most common reason for revision was aseptic loosening of the tibial tray (23/49 revisions, 47%). All PROMs were comparable with the reference values of the Dutch Arthroplasty Register. History of knee surgery prior to TKA was not associated with survival or PROMs. Conclusion The LCS uncemented mobile bearing knee implant provides excellent survival and patient satisfaction in our cohort. Previous surgery does not seem to compromise results in our population.
Article
Background: Total knee replacements (TKRs) can be implanted with or without the use of cement. It is currently uncertain how cemented and cementless TKRs compare overall and in different age groups of the population in the long term. Methods: The National Joint Registry collects information on knee replacements inserted in England, Wales, Northern Ireland, and the Isle of Man and was linked for multiple confounders to the National Health Service Hospital Episode Statistics database. With use of propensity score matching techniques, 44,954 cemented and cementless TKRs were compared. Regression models were used to compare the outcomes of revision, reoperation, and mortality both overall and in different age strata. Results: The 10-year implant survival rate with revision as the end point for cemented and cementless TKRs was 96.0% and 95.5%, respectively (hazard ratio [HR] = 1.14; p = 0.01). The 10-year survival rate with reoperation as the end point was 82.7% and 81.4%, respectively (HR = 1.08; p = 0.001). The rate of revision for pain was higher for cementless TKRs (0.5% [cemented] compared with 0.7% [cementless]; p = 0.002), but the rate of revision for infection was lower (0.7% [cemented] compared with 0.5% [cementless]; p = 0.003). No significant interactions with age existed for the outcomes of revision (p = 0.24), reoperation (p = 0.30), or mortality (p = 0.58). Conclusions: We found that matched cemented and cementless TKRs both have 10-year implant survival rates of >95%. Cementless TKRs had a higher revision rate (absolute difference, 0.5%) and reoperation rate (absolute difference, 1.3%). The rate of revision for infection was lower in the cementless group, although the rate of revision for pain was higher. Age did not significantly affect the relative performances. Level of evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
Article
Full-text available
Background The potential advantages of hydroxyapatite (HA)-coated cementless total knee arthroplasty (TKA) implants are bone stock preservation and biological fixation. Studies comparing the outcomes of HA-coated cementless, non HA-coated cementless (uncemented) and cemented TKA implants reported contradictory data. Our aim was to provide a comparison of the effects of HA coating of tibial stem on the stability and functionality of TKA implants. Methods A systematic literature search was performed using MEDLINE, Scopus, EMBASE and the CENTRAL databases up to May 31st, 2019. The primary outcome was Maximum Total Point Motion (MTPM) of the tibial stem. This parameter is determined by radiosterometric analysis and refers to the migration pattern of the prosthesis stems. The clinical outcomes of the implanted joints were evaluated by the Knee Society Knee Score (KSS) and the Knee Society Function Score (KFS). Weighted mean difference (WMD) with 95% confidence interval (CI) were calculated with the random-effects model. Results Altogether, 11 randomized controlled trials (RCTs) with 902 patients for primary TKA implants were included. There was a statistically significant difference in the MTPM values with the use of HA-coated and uncoated uncemented implants (WMD = +0.28, CI: +0.01 to +0.56, P<0.001). However, HA-coated stems showed significantly higher migration when compared with the cemented prostheses (WMD = -0.29, CI: -0.41 to -0.16, P<0.001). The KSS values of HA-coated implants were significantly higher than those for the uncemented implants; moreover, KSS and KFS outcome scores were statistically not different between the HA-coated and cemented prosthesis cases. Conclusion HA-coating yields better stability than other, uncemented prostheses. More importantly, the HA-coating is not outperformed by cemented prosthesis in providing good functional outcome.
Article
Aims: Although bone cement is the primary mode of fixation in total knee arthroplasty (TKA), cementless fixation is gaining interest as it has the potential of achieving lasting biological fixation. By 3D printing an implant, highly porous structures can be manufactured, promoting osseointegration into the implant to prevent aseptic loosening. This study compares the migration of cementless, 3D-printed TKA to cemented TKA of a similar design up to two years of follow-up using radiostereometric analysis (RSA) known for its ability to predict aseptic loosening. Methods: A total of 72 patients were randomized to either cementless 3D-printed or a cemented cruciate retaining TKA. RSA and clinical scores were evaluated at baseline and postoperatively at three, 12, and 24 months. A mixed model was used to analyze the repeated measurements. Results: The mean maximum total point motion (MTPM) at three, 12, and 24 months was 0.33 mm (95% confidence interval (CI) 0.25 to 0.42), 0.42 mm (95% CI 0.33 to 0.51), and 0.47 mm (95% CI 0.38 to 0.57) respectively in the cemented group, versus 0.52 mm (95% CI 0.43 to 0.63), 0.62 mm (95% CI 0.52 to 0.73), and 0.64 mm (95% CI 0.53 to 0.75) in the cementless group (p = 0.003). However, using three months as baseline, no difference in mean migration between groups was found (p = 0.497). Three implants in the cemented group showed a > 0.2 mm increase in MTPM between one and two years of follow-up. In the cementless group, one implant was revised due to pain and progressive migration, and one patient had a liner-exchange due to a deep infection. Conclusion: The cementless TKA migrated more than the cemented TKA in the first two-year period. This difference was mainly due to a higher initial migration of the cementless TKA in the first three postoperative months after which stabilization was observed in all but one malaligned and early revised TKA. Whether the biological fixation of the cementless implants will result in an increased long-term survivorship requires a longer follow-up. Cite this article: Bone Joint J 2020;102-B(8):1016-1024.
Article
PurposeThe aim of this study was to report and compare the long-term revision rate, revision indications and patient reported outcome measures of cemented and cementless unicompartmental knee replacements (UKR).Methods Databases Medline, Embase and Cochrane Central of Controlled Trials were searched to identify all UKR studies reporting the ≥ 10 year clinical outcomes. Revision rates per 100 component years [% per annum (% pa)] were calculated by fixation type and then, subgroup analyses for fixed and mobile bearing UKRs were performed. Mechanisms of failure and patient reported outcome measures are reported.Results25 studies were eligible for inclusion with a total of 10,736 UKRs, in which there were 8790 cemented and 1946 cementless knee replacements. The revision rate was 0.73% pa (CI 0.66–0.80) and 0.45% pa (CI 0.34–0.58) per 100 component years, respectively, with the cementless having a significantly (p < 0.001) lower overall revision rate. Therefore, based on these studies, the expected 10-year survival of cementless UKR would be 95.5% and cemented 92.7%. Subgroup analysis revealed this difference remained significant for the Oxford UKR (0.37% pa vs 0.77% pa, p < 0.001), but for non-Oxford UKRs there were no significant differences in revision rates of cemented and cementless UKRs (0.57% pa vs 0.69% pa, p = 0.41). Mobile bearing UKRs had significantly lower revision rates than fixed bearing UKRs in cementless (p = 0.001), but not cemented groups (p = 0.13). Overall the revision rates for aseptic loosening and disease progression were significantly lower (p = 0.02 and p = 0.009 respectively) in the cementless group compared to the cemented group (0.06 vs 0.13% pa and 0.10 vs 0.21% pa respectively).Conclusions Cementless fixation had reduced long-term revision rates compared to cemented for the Oxford UKR. For the non-Oxford UKRs, the revision rates of cementless and cemented fixation types were equivalent. Therefore, cementless UKRs offer at least equivalent if not lower revision rates compared to cemented UKRs.Level of evidenceIII.
Article
Background Recent studies have demonstrated that aseptic loosening remains a leading cause of failure after total knee arthroplasty (TKA). Cementless fixation is a possible strategy for countering this problem. This study compared short-term survivorship and functional results of patients undergoing primary TKA with cementless versus cemented implants. Methods A multi-center database was utilized to identify 3849 patients undergoing primary TKA between 2012 and 2017 with a minimum two-year follow-up. Patients were divided into cementless (699), and cemented TKA (3150). The outcome of TKA including revision for aseptic or septic reasons, and other outcome variables were compared. Six hundred five patients from the cementless group (case) were matched with 605 patients from the cemented group (controls). Both groups were compared for outcomes and related variables. Results Both matched groups were similar in age, race, gender, height, weight, BMI, laterality, femoral component type, follow-up duration, preoperative and postoperative physical and mental health, and functional activities (all p-values >0.05). Although the cementless TKA group had more components in varus alignment (p = 0.015) and were taller (p < 0.001), the aseptic revision rate and time to failure were similar in both groups (p-values = 0.256 and 0.0890 respectively). The rate of revision for infection was also the same in both groups (p = 0.452). Conclusion Cementless TKA demonstrated an equivalent rate of aseptic and septic failure when compared to cemented TKA in the short-term. Time to aseptic failure was also similar in both groups.
Article
Background Unicompartmental knee replacement (UKR) is a common treatment option for patients with advanced medial compartment knee arthritis. The Oxford UKR (OUKR) is the most commonly used implant for partial knee replacement. A cementless Oxford prosthesis was introduced in 2004 aiming to reduce the revision rate by potentially reducing radiolucencies as well as errors of cementation associated with the cemented prosthesis. Whilst results from the designer centre have been reported, there is little independent clinical evidence of outcomes. The aim of this study was to evaluate the survival of the cementless OUKR in a single surgeon series at an independent centre and to assess clinical and radiographic outcomes. Methods All patients who received a cementless medial OUKR and had a minimum of five-year follow-up were included in the series. The Oxford knee score was used to evaluate patient outcomes at five years postoperatively. Survival rates, complications and evidence of radiolucencies on plain radiographs were also reviewed. Results One hundred and fifty-eight cementless medial OUKR were implanted in 126 patients. Three patients died and four knees were revised. The five-year survival was 97.4% and the median Oxford knee score was 43 at five years postoperatively. No Complete radiolucent lines were observed on radiographs at one year. Four tibial components subsided. Conclusions This independent series shows that low revision rates and excellent results can be achieved with the use of the cementless OUKR at five years. Early subsidence of the tibial component, which is specific to the cementless prosthesis, warrants further investigation.
Article
Physical activity is essential for overall health. For patients undergoing knee arthroplasty, questions about the implant's suitability for sports arise. The general recommendations for physical activity with knee replacements are often based upon experts' opinions, with a lack of scientific data. This study was performed at an independent high-volume center and aimed to investigate what level of activity patients can achieve and how they perform with a well-functioning cementless unicompartmental knee replacement (UKR). Possible differences in outcome in regards to patients' body mass index (BMI) were also examined. A total of 228 knees treated with cementless Oxford UKR (OUKR) were followed up after a mean of 37.1 months. Tegner's and UCLA (University of California, Los Angeles) scores were obtained to assess the level of physical activity. The Schulthess Clinical Activity Questionnaire was assessed for detailed information on practiced sports, and the SF-36 questionnaire was evaluated to analyze patients' quality of life. The return to activity rate was 92.9%. In total, 64% of the physically active patients had already taken up sports within 3 months after surgery. Mean Tegner's score was at 3.5, and mean UCLA score was at 6.3. High impact sports were not performed very often after surgery. Higher BMI showed a negative correlation with the numbers of sports (rsp = −0.289) as well as Tegner's (rsp = −0.222) and UCLA (rsp = −0.383) scores. The SF-36 scores were comparably good to those in an age-equivalent standard reference group. In conclusion, cementless OUKR allows a fast return to activity with a high level of physical exercise. Patients with increased BMI tend to practice less types of sports with decreased activity scores.
Article
The number of total knee arthroplasties (TKAs) performed in the United States has increased considerably in recent years, with a major contribution from younger patients. Maximizing survivorship of these implants has always been a point of emphasis. Early TKA designs with cementless fixation were associated with high rates of complications and implant failures. However, recent advances in cementless designs have shown excellent results. The decision to use cemented or cementless fixation for patients undergoing TKA is typically based on the surgeon's experience and preference. However, several patient characteristics must also be taken into account. The purpose of this review was to describe the clinical outcomes of studies in which a cementless TKA system was utilized for patients who (1) were less than 60 years of age, (2) were greater than 75 years of age, (3) were obese, (4) had rheumatoid arthritis, and (5) had osteonecrosis of the knee. Based on the studies included in this review, it appears that cementless fixation is a viable option for patients who have all of the above demographics.
Article
Dissatisfaction following total knee arthroplasty is a well-documented phenomenon. Although many factors have been implicated, including modifiable and nonmodifiable patient factors, emphasis over the past decade has been on implant alignment and stability as both a cause of, and a solution to, this problem. Several alignment targets have evolved with a proliferation of techniques following the introduction of computer and robotic-assisted surgery. Mechanical alignment targets may achieve mechanically-sound alignment while ignoring the soft tissue envelope; kinematic alignment respects the soft tissue envelope while ignoring the mechanical environment. Functional alignment is proposed as a hybrid technique to allow mechanically-sound, soft tissue-friendly alignment targets to be identified and achieved. Cite this article: Bone Joint J 2020;102-B(3):276–279.
Article
Background: Unicompartmental knee replacement (UKR) offers substantial benefits compared with total knee replacement (TKR) but is associated with higher revision rates. Data from registries suggest that revision rates for cementless UKR implants are lower than those for cemented implants. It is not known how much of this difference is due to the implant or to other factors, such as a greater proportion of high-volume surgeons using cementless implants. We aimed to determine the effect of surgeon caseload on the revision rate of matched cemented and cementless UKRs. Methods: From a group of 40,522 Oxford (Zimmer Biomet) UKR implants (30,814 cemented, 9,708 cementless) recorded in the National Joint Registry, 14,814 (7,407 cemented, 7,407 cementless) were propensity-score matched. Surgeons were categorized into 3 groups: low volume (<10 cases/year), medium volume (10 to <30 cases/year), and high volume (≥30 cases/year). The effect of caseload on the relative risk of revision was assessed with use of Cox regression. Results: The 10-year survival rates for unmatched cementless and cemented UKR implants were 93.3% (95% confidence interval [CI] = 89.8% to 95.7%) and 89.1% (95% CI = 88.6% to 89.6%), respectively, with the difference being significant (hazard ratio [HR] = 0.59; p < 0.001). Cementless UKR implants had a greater proportion of high-volume surgeon users than cemented implants (30.4% compared with 15.1%). Following matching, the 10-year survival rates were 93.2% (95% CI = 89.7% to 95.6%) and 90.2% (95% CI = 87.5% to 92.3%), which were still significantly different (HR = 0.76; p = 0.002). The 10-year survival rates for matched cementless and cemented UKR implants were 86.8% (95% CI = 73.6% to 93.7%) and 81.8% (95% CI = 73.0% to 88.0%) for low-volume surgeons, 94.3% (95% CI = 92.2% to 95.9%) and 92.5% (95% CI = 89.9% to 94.5%) for medium-volume surgeons, and 97.5% (95% CI = 96.5% to 98.2%) and 94.2% (95% CI = 90.8% to 96.4%) for high-volume surgeons. The revision rate for cementless implants was lower for surgeons in all 3 caseload groups (HR = 0.74, 0.79, 0.80, respectively). Conclusions: Cementless fixation decreased the revision rate by about a quarter, whatever the surgeon caseload. Caseload had a profound effect on implant survival. Low-volume surgeons had a high revision rate with cemented or cementless fixation and therefore should consider either stopping or doing more UKR procedures. High-volume surgeons performing cementless UKR demonstrated a 10-year survival rate of 97.5%, which was similar to that reported in registries for the best-performing TKRs. Level of evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.