ArticlePDF Available

Clinical outcome using a ligament referencing technique in CAS versus conventional technique


Abstract and Figures

Computer-assisted surgery (CAS) for total knee arthroplasty (TKA) has become increasingly common over the last decade. There are several reports including meta-analyses that show improved alignment, but the clinical results do not differ. Most of these studies have used a bone referencing technique to size and position the prosthesis. The question arises whether CAS has a more pronounced effect on strict ligamentous referencing TKAs. We performed a prospective cohort study comparing clinical outcome of navigated TKA (43 patients) with that of conventional TKA (122 patients). Patients were assessed preoperatively, and 2 and 12 months postoperatively by an independent study nurse using validated patient-reported outcome tools as well as clinical examination. At 2 months, there was no difference between the two groups. However, after 12 months, CAS was associated with significantly less pain and stiffness, both at rest and during activities of daily living, as well as greater overall patient satisfaction. The present study demonstrated that computer-navigated TKA significantly improves patient outcome scores such as WOMAC score (P=0.002) and Knee Society score (P=0.040) 1 year after surgery in using a ligament referencing technique. Furthermore, 91% were extremely or very satisfied in the CAS TKA group versus 70% after conventional TKA (P=0.007).
Content may be subject to copyright.
Clinical outcome using a ligament referencing technique
in CAS versus conventional technique
K. Lehnen K. Giesinger R. Warschkow
M. Porter E. Koch M. S. Kuster
Received: 16 March 2010 / Accepted: 31 August 2010 / Published online: 18 September 2010
ÓThe Author(s) 2010. This article is published with open access at
Purpose Computer-assisted surgery (CAS) for total knee
arthroplasty (TKA) has become increasingly common over
the last decade. There are several reports including meta-
analyses that show improved alignment, but the clinical
results do not differ. Most of these studies have used a bone
referencing technique to size and position the prosthesis.
The question arises whether CAS has a more pronounced
effect on strict ligamentous referencing TKAs.
Methods We performed a prospective cohort study com-
paring clinical outcome of navigated TKA (43 patients) with
that of conventional TKA (122 patients). Patients were
assessed preoperatively, and 2 and 12 months postopera-
tively by an independent study nurse using validated patient-
reported outcome tools as well as clinical examination.
Results At 2 months, there was no difference between the
two groups. However, after 12 months, CAS was associ-
ated with significantly less pain and stiffness, both at rest
and during activities of daily living, as well as greater
overall patient satisfaction.
Conclusion The present study demonstrated that com-
puter-navigated TKA significantly improves patient out-
come scores such as WOMAC score (P=0.002) and Knee
Society score (P=0.040) 1 year after surgery in using a
ligament referencing technique. Furthermore, 91% were
extremely or very satisfied in the CAS TKA group versus
70% after conventional TKA (P=0.007).
Keywords Knee arthroplasty TKA
Computer navigation CAS Patient outcome
Ligament referencing technique
Despite excellent long-term results of total knee arthropla-
sties (TKA) [27,37], premature failure still occurs and early
loosening due to prosthesis mal-alignment remains a major
factor [40]. Almost one-third of all early revisions are
potentially avoidable with more accurate component posi-
tioning and ligament balancing [40]. Even though com-
puter-assisted surgery (CAS) has been shown to improve
implant positioning of the femoral and tibial component and
to restore more precisely the mechanical axis in TKA [13,
16,17], long-term results are lacking and there is no evi-
dence yet that CAS also improves patient satisfaction [43].
Most prospective studies did concentrate on the radiological
evaluation [2,12,17,23,32,34,42,47], and only few
included self-reported questionnaires such as WOMAC
score or others [10,16,30,31].
Two different approaches have emerged to establish the
exact component position (bone referencing versus liga-
ment referencing). Most CAS programs use bony land-
marks to establish size, rotation and position of the
components. Ligamentous releases are performed at the
end of the procedure to fine-tune the ligament balancing.
The ligament referencing technique on the other hand uses
a flexion-gap-first technique, and the ligament tension at
90 deg of knee flexion determines rotation, exact position
and size of the femoral component. Hence, the ligament
K. Lehnen K. Giesinger R. Warschkow E. Koch
M. S. Kuster (&)
Klinik fu
¨r Orthopa
¨dische Chirurgie und Traumatologie
des Bewegungsapparates, Rorschacherstrasse 97,
9007 St. Gallen, Switzerland
M. Porter
Calvary Clinic, Haydon Drive, Bruce, ACT 2617, Australia
Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892
DOI 10.1007/s00167-010-1264-4
referencing technique might profit more from CAS than
bone referencing techniques. It was the aim of the present
study to determine whether CAS improves patient satis-
faction and function two and 12 months postoperatively
using a strict ligament referencing technique.
Materials and methods
A prospective non-randomized cohort study was con-
ducted. All patients undergoing a primary LCS TKA
between 2006 and 2007 were included in the study.
Patients with previous knee surgery (except arthroscopy)
were excluded from the study. The choice whether CAS or
a conventional technique was applied depended on the
availability of the navigation system as well as the con-
venience of the theater list.
All patients gave informed consent to participate in the
study, and ethical approval was attained from the Cantonal
Review Board of St. Gallen.
Surgical technique
All procedures were performed with a tourniquet. A medial
parapatellar approach was the standard approach. In cases
of valgus deformity, patella baja or preoperative patella
subluxation, a lateral subvastus approach with tuberosity
osteotomy was used [20]. All patients received an LCS
mobile-bearing prosthesis (DePuy Low Contact Stress
Complete Knee System, Leeds, UK). A tibia-first and
flexion-gap-first technique was used for both groups. The
PCL was resected in all cases.
For patients in the non-navigated group, an intramed-
ullary femoral and an extramedullary tibial alignment
guide was used. Ligament tension in flexion determined
femoral component size and femoral rotation. The flexion
gap was routinely left 2–3 mm looser than the extension
gap to improve postoperative ROM [22]. The patella was
not routinely resurfaced. All knees were cemented. All
knees underwent the same standard post-TKA rehabilita-
tion program.
For patients in the navigated group, the Vector Vision
navigation system (CT-free, optoelectronic, passive marker
navigation system (BrainLab, Munich, Germany)) was
used. After the tibial cut had been made, the flexion gap
and extension gap were measured using a spring-loaded
sensor tensor (Fig. 1). The femoral component size, antero-
posterior position and femoral rotation were determined to
fill the flexion gap. As with the conventional technique, the
flexion gap was created 2–3 mm looser than the extension
gap. Using navigation, in combination with the spring-
loaded sensor tensor, the position and size of the femur
component could be determined precisely to obtain a
slightly looser flexion gap.
Outcome assessment
The WOMAC score and Knee Society score (KSS) were
used to measure clinical outcome. The Western Ontario
and McMaster University Arthritis Index (WOMAC) has
been validated for both preoperative and postoperative use
in TKA [18]. The Knee Society score (KSS) consists of a
knee referring subscale, based on clinical parameters, and a
patient function score during specific activities, such as
climbing stairs and walking [38].
Prior to admission, all patients were posted the WOMAC
score to fill in. The Knee Society score was completed on the
day of admission. All patients were reviewed at 2 and
12 months postoperatively by the same research nurse.
At the 1-year follow-up, all patients were asked how
satisfied they were with the operation (‘‘extremely’’, ‘‘very’’,
‘moderately’’, ‘‘slightly’’ or ‘‘not at all’’) and whether they
would undergo the operation again (‘‘yes’’ or ‘‘no’’).
Statistical analysis
Student’s ttest and analysis of variance were performed for
continuousvariables (age, BMI, hospital stay, operation time).
Fig. 1 Spring-loaded sensor tensor
888 Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892
Two-sided significance tests were used throughout. Propor-
tions were compared by using chi-squared tests with conti-
nuity correction or Fisher’s exact test when appropriate for
categorical variables (complication rate, outcome scores,
subjective outcome measurement).
Confirmatory analysis of knee scores was done using
t-tests with adjustment for multiplicity by the Bonferroni–
Holm procedure [21]. Statistical analysis was performed
using SPSS 14.0 for Windows (SPSS Inc, Chicago, IL).
The level for statistical significance was set a priori to
\0.05 for all tests.
The scores were adjusted for BMI and preoperative
values by an analysis of covariance.
A priori sample size determination was based on 80%
power (P=0.05, two-sided) to detect a difference of 10
points in WOMAC total score with a standard deviation of
20 points [43] revealed that 168 patients were needed when
the ratio of navigated to non-navigated patients was 1:3.
A cohort of 166 patients was included in this study. One
patient was not available for follow-up because he relo-
cated from the hospital service area (navigated group).
There were no adverse events reported for this patient, and
the data were excluded from the analysis. Of the remaining
165 patients, 43 had a CAS TKA (navigated group) and
122 patients had a conventional TKA (non-navigated
group). A lateral approach was used in 25% of patients in
the navigated and non-navigated group. All other patients
had a standard medial parapatellar approach. The patella
was resurfaced in one patient (navigated group).
The two groups were similar with regard to age and
sex distribution (Table 1). BMI was significantly lower
(P=0.037) in the navigated group. This difference was
adjusted for in the statistical analysis of the outcome
scores. Knee flexion–extension range of motion was simi-
lar for the navigated and non-navigated groups and did not
change from preoperatively up to 12 months postopera-
tively in either group (Table 2).
The navigated and non-navigated groups had similar
KSS scores preoperatively and 2 months postoperatively
(Table 3). However, at 12 months, the navigated group had
higher scores than the non-navigated group (Table 3). In
addition, 12 months postoperatively, the navigated group
showed less pain during walking (P=0.002), at rest
(P=0.023) and while climbing stairs (P=0.034). Also,
the total WOMAC score was significantly lower 12 months
postoperatively in the navigated group compared to the
non-navigated group (Table 3). The difference was also
significant for all WOMAC subscales (pain, stiffness and
physical function).
Twelve months postoperatively, patients in the navi-
gated group were more satisfied with their knee replace-
ment compared to patients in the non-navigated group
(Table 4).
Overall, there were 14 postoperative complications
(Table 5). The number of incidences was too small for
meaningful statistical analysis. Nevertheless, it is note-
worthy that no DVT occurred in the navigated group. One
complication that is unique to the CAS was a fracture of the
tip of a Schanz pin. The tip of the pin was left in situ. The
other complication was a fissural fracture in one patient in
the navigated group who presented with an undisplaced
incomplete fissure of the cortex after tibial tuberosity
osteotomy at the site of the pin insertion for the surgical
block. The fracture was fixed with two interfragmentary
screws as a prophylactic measure.
In contrast to recent literature [1,36,8,9,1214,16,17,
21,25,28,33,35,39,4143,45,47], the results of the
present study showed a clear benefit of CAS regarding
WOMAC and KSS compared to a non-navigated tech-
nique. The disparate results raise the question of what
could have caused these different findings. We believe the
operating technique might be a reason. Most studies used a
bone referencing technique [12,33,43]. The present study
Table 1 Demographic data for patients in the navigated and the
non-navigated groups
Female 23 (54%) 83 (68%) n.s.
Male 20 (47%) 39 (32%)
BMI [kg/m
]28±530±6 0.037
Age [years] 68 ±870±10 n.s.
Hospital stay [days] 13 ±412±5 n.s.
Operation time [min] 102 ±14 95 ±19 0.030
Table 2 Knee flexion–extension range of motion in degrees (mean ±
1SD) for the navigated and non-navigated groups preoperatively, and at
2 months and 12 months postoperatively
Navigated Non-navigated P-value
Preoperatively 114°±18°110°±17°0.188
2 months 104°±18°103°±16°n.s.
12 months 116°±12°114°±12°n.s.
Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892 889
applied a strict ligament referencing technique in flexion
and extension, which might be more sensitive to cumula-
tive errors than a bone referencing technique. In the liga-
ment referencing technique, femoral size and rotation are
established with a distraction device such as the spring-
loaded tensioning device (Fig. 1) to fill and obtain a rect-
angular flexion gap. This strongly depends on an accurate
tibial cut and correct tensioning of the medial and lateral
collateral ligaments. Also in extension, the femoral bone
cut is influenced by the tibial cut. Because of the strong
dependency of each bone cut from the previous cut, small
errors add up in the ligament referencing technique.
Longstaff et al. [29] showed in a prospective study that
patients with a low cumulative error (\6°) showed faster
rehabilitation and a significantly better functional outcome.
There are further studies [10,15] supporting the present
results. Choong et al. [10] demonstrated in a prospective
randomized study that patients with a coronal alignment of
B3°showed a better functional outcome and higher quality
of life scores. And in a retrospective case matched study of
50 patients per group, Ek et al. [15] found significantly
better SF12 quality of life and International Knee Society
scores (KSS) when CAS was used. Kelley et al. showed
that ligament referencing CAS in combination with the
Table 3 Clinical outcome assessment scores (mean ±1SD) adjusted for multiplicity with Bonferroni–Holm [21]
Scores Preoperative data 12-months follow-up
nNavigated Non-navigated P-value nNavigated Non-navigated P-value
Knee Society score (KSS)
Total (0–200) 164 111 ±32 97 ±29 0.373 162 177 ±21 159 ±30 0.043
Function score 166 65 ±19 57 ±19 0.353 164 90 ±15 80 ±18 0.025
Knee score 164 47 ±18 40 ±17 0.168 162 87 ±10 80 ±17 0.018
Total score (0–96) 154 50 ±18 55 ±17 1.000 166 9 ±10 21 ±19 0.001
Pain (0–20) 154 11 ±412±4 0.828 166 1 ±24±4 0.000
Stiffness (0–8) 154 4 ±25±2 1.000 166 1 ±12±2 0.003
Physical function (0–68) 154 35 ±13 39 ±13 1.000 166 7 ±915±14 0.004
Table 4 Subjective outcome
measurement after 1 year
Are you satisfied with your prosthesis?
(extremely/very satisfied with TKA)
39 (91%) 85/121 (70%) 0.007
Would you undergo the operation again? 42 (98%) 102/120 (85%) 0.026
Table 5 Intraoperative
complication and complications
at 2 months postoperatively
nCAS Conventional P-value
Intraoperatively 165 n=43 n=122
Local complications 11 (7%) 2 (5%) 9 (7%) n.s.
Fissural fracture 1 (2%) 1 (1%)
Lesion of popliteal tendon 1 (2%) 4 (3%)
Fracture 0 1 (1%)
Other local complications 0 3 (3%)
2 months postoperatively 165 n=43 n=122
Overall complications 21 (12.7%) 1 (2%) 20 (16%) n.s.
Transient lesion of peroneal nerve 0 1 (1%)
Deep infection 0 1 (1%)
Superficial wound healing problems 0 4 (3%)
Clinical DVT 0 7 (6%)
Subcutaneous hematoma 0 4 (3%)
Intraarticular hematoma 1 (2%) 0
Other local complication 0 3 (3%)
890 Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892
same spring-loaded tensioning device (Fig. 1) significantly
reduced the postoperative manipulation rate from 16 to 7%
[26]. This spring-loaded sensor tensor was also used in the
CAS group, but was not used in the conventional group.
Hence, it is impossible to determine whether the spring-
loaded device alone, CAS alone or the combination of both
CAS and sensor tensor caused our significant findings.
The CAS group did show a significantly longer opera-
tion time of 7 min. This time difference might seem small
considering the necessary registration of the knee joint in
the CAS group. We also did measure independently the
time necessary for the pin insertion and the registration of
the computer. It was well possible to perform these mea-
sures within 6 to 9 min. This time difference is also in
agreement with the literature. Kalairajah et al. [24] showed
a mean difference of 13 min, Lu
¨tzner et al. [30] 9 min and
Stulberg et al. [46] 7–10 min using the latest hardware and
Interestingly, no clinically relevant thromboembolic
complications incurred in the navigated group compared to
seven deep venous thromboses in the non-navigated group
suggesting that thromboembolic complications may be
reduced by CAS [11,24]. Computer-aided surgery obviates
the need for an intramedullary device at the femur. Church
et al. [11] performed a double-blind randomized study to
compare the incidence of fat embolic phenomena between
navigated and non-navigated knee prosthesis and demon-
strated a significantly reduced embolic burden in the CAS
group. Fat and bone marrow is a potential activator of the
clotting system and is thought an important factor for deep
venous thrombosis in major orthopedic procedures. In a
prospective randomized study after total hip arthroplasty,
Pitto et al. [36] found a lower incidence of deep venous
thrombosis in cases where an intraoperative prophylaxis
against fat and bone marrow embolism was performed. It
seems feasible that CAS reduces the intraoperative embo-
lization of potential activators of the clotting cascade and
thereby lowers the rate of DVTs.
A real limitation of this study was the lack of random-
ization. However, the study reported results on a large
number of patients with complete follow-up of all but one
patient. In addition, an independent study nurse performed
all clinical preoperative and postoperative investigations.
The two patient groups were comparable with regard to
age, sex and co-morbidities. The navigated group had a
lower BMI than the non-navigated group, and this could
also be a potentially confounding factor. The significant
improvements also remained after adjustments for the
BMI by an analysis of covariance. Also, in the literature,
BMI does not appear to be a strong predictor of postop-
erative pain or patient satisfaction following arthroplasty
The results of this 12-month follow-up study demonstrated
that CAS produced better clinical outcome compared to
traditional surgery in ligament referencing TKA after one
year. Further refinements of computer navigation systems
might not only advance radiological alignment but also
pain and stiffness after TKA, which are both very influ-
ential parameters for patient satisfaction and mobility.
Open Access This article is distributed under the terms of the
Creative Commons Attribution Noncommercial License which per-
mits any noncommercial use, distribution, and reproduction in any
medium, provided the original author(s) and source are credited.
1. Anderson KC, Buehler KC, Markel DC (2005) Computer assisted
navigation in total knee arthroplasty: Comparison with conven-
tional methods. J Arthroplasty 20 7 Suppl 3:132–138
2. Bathis H, Perlick L, Tingart M, Luring C et al (2004) Alignment
in total knee arthroplasty. A comparison of computer-assisted
surgery with the conventional technique. J Bone Joint Surg Br
3. Bathis H, Shafizadeh S, Paffrath T, Simanski C et al (2006) Are
computer assisted total knee replacements more accurately
placed? A meta-analysis of comparative studies. Orthopade
4. Bauwens K, Matthes G, Wich M, Gebhard F et al (2007) Navi-
gated total knee replacement. A meta-analysis. J Bone Joint Surg
Am 89(2):261–269
5. Bertsch C, Holz U, Konrad G, Vakili A et al (2007) Early clinical
outcome after navigated total knee arthroplasty. Comparison with
conventional implantation in tka: a controlled and prospective
analysis. Orthopade 36(8):739–745
6. Bolognesi M, Hofmann A (2005) Computer navigation versus
standard instrumentation for tka: a single-surgeon experience.
Clin Orthop Relat Res 440:162–169
7. Bourne RB, McCalden RW, MacDonald SJ, Mokete L et al
(2007) Influence of patient factors on tka outcomes at 5 to
11 years followup. Clin Orthop Relat Res 464:27–31
8. Chauhan SK, Scott RG, Breidahl W, Beaver RJ (2004) Com-
puter-assisted knee arthroplasty versus a conventional jig-based
technique. A randomised, prospective trial. J Bone Joint Surg Br
9. Chin PL, Yang KY, Yeo SJ, Lo NN (2005) Randomized control
trial comparing radiographic total knee arthroplasty implant
placement using computer navigation versus conventional tech-
nique. J Arthroplasty 20(5):618–626
10. Choong PF, Dowsey MM, Stoney JD (2009) Does accurate
anatomical alignment result in better function and quality of life?
Comparing conventional and computer-assisted total knee
arthroplasty. J Arthroplasty 24(4):560–569
11. Church JS, Scadden JE, Gupta RR, Cokis C et al (2007) Embolic
phenomena during computer-assisted and conventional total knee
replacement. J Bone Joint Surg Br 89(4):481–485
12. Decking R, Markmann Y, Fuchs J, Puhl W et al (2005) Leg axis
after computer-navigated total knee arthroplasty: a prospective
randomized trial comparing computer-navigated and manual
implantation. J Arthroplasty 20(3):282–288
Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892 891
13. Decking R, Markmann Y, Mattes T, Puhl W et al (2007) On the
outcome of computer-assisted total knee replacement. Acta Chir
Orthop Traumatol Cech 74(3):171–174
14. Dutton AQ, Yeo SJ, Yang KY, Lo NN et al (2008) Computer-
assisted minimally invasive total knee arthroplasty compared
with standard total knee arthroplasty. A prospective, randomized
study. J Bone Joint Surg Am 90(1):2–9
15. Ek ET, Dowsey MM, Tse LF, Riazi A et al (2008) Comparison of
functional and radiological outcomes after computer-assisted
versus conventional total knee arthroplasty: a matched-control
retrospective study. J Orthop Surg (Hong Kong) 16(2):192–196
16. Ensini A, Catani F, Leardini A, Romagnoli M et al (2007)
Alignments and clinical results in conventional and navigated
total knee arthroplasty. Clin Orthop Relat Res 457:156–162
17. Haaker RG, Stockheim M, Kamp M, Proff G et al (2005) Com-
puter-assisted navigation increases precision of component
placement in total knee arthroplasty. Clin Orthop Relat Res
18. Hawker G, Melfi C, Paul J, Green R et al (1995) Comparison of a
generic (sf-36) and a disease specific (womac) (western ontario
and mcmaster universities osteoarthritis index) instrument in the
measurement of outcomes after knee replacement surgery.
J Rheumatol 22(6):1193–1196
19. Hawker G, Wright J, Coyte P, Paul J et al (1998) Health-related
quality of life after knee replacement. J Bone Joint Surg Am
20. Hay GC, Kampshoff J, Kuster MS (2010) Lateral subvastus
approach with osteotomy of the tibial tubercle for total knee
replacement: a two-year prospective, randomised, blinded con-
trolled trial. J Bone Joint Surg Br 92(6):862–866
21. Holm S (1979) A simple sequentially rejective multiple test
procedure. Scand J Statist 6:65–70
22. Jeffcote B, Nicholls R, Schirm A, Kuster MS (2007) The varia-
tion in medial and lateral collateral ligament strain and tibio-
femoral forces following changes in the flexion and extension
gaps in total knee replacement a laboratory experiment using
cadaver knees. J Bone Joint Surg Br 89(11):1528–1533
23. Jenny JY, Clemens U, Kohler S, Kiefer H et al (2005) Consis-
tency of implantation of a total knee arthroplasty with a non-
image-based navigation system: a case-control study of 235 cases
compared with 235 conventionally implanted prostheses.
J Arthroplasty 20(7):832–839
24. Kalairajah Y, Cossey AJ, Verrall GM, Ludbrook G et al (2006)
Are systemic emboli reduced in computer-assisted knee surgery?
A prospective, randomised, clinical trial. J Bone Joint Surg Br
25. Kamat YD, Aurakzai KM, Adhikari AR, Matthews D et al (2009)
Does computer navigation in total knee arthroplasty improve
patient outcome at midterm follow-up? Int Orthop 33(6):
26. Kelley T, Swank M (2008) Computer-assisted surgery in total
knee arthroplasty: experience with the vectorvision and ci navi-
gation system for mobile bearing total knee arthroplasty. Tech
Knee Surg 7(3):144–152
27. Kelly MA, Clarke HD (2002) Long-term results of posterior
cruciate-substituting total knee arthroplasty. Clin Orthop Relat
Res 404:51–57
28. Kim SJ, MacDonald M, Hernandez J, Wixson RL (2005) Com-
puter assisted navigation in total knee arthroplasty: improved
coronal alignment. J Arthroplasty 20 7 Suppl 3:123–131
29. Longstaff LM, Sloan K, Stamp N, Scaddan M et al (2009) Good
alignment after total knee arthroplasty leads to faster rehabilita-
tion and better function. J Arthroplasty 24(4):570–578
30. Lutzner J, Krummenauer F, Wolf C, Gunther KP et al (2008)
Computer-assisted and conventional total knee replacement: a
comparative, prospective, randomised study with radiological and
ct evaluation. J Bone Joint Surg Br 90(8):1039–1044
31. Martin A, Wohlgenannt O, Prenn M, Oelsch C et al (2007)
Imageless navigation for tka increases implantation accuracy.
Clin Orthop Relat Res 460:178–184
32. Matziolis G, Krocker D, Weiss U, Tohtz S et al (2007) A pro-
spective, randomized study of computer-assisted and conventional
total knee arthroplasty. Three-dimensional evaluation of implant
alignment and rotation. J Bone Joint Surg Am 89(2):236–243
33. Molfetta L, Caldo D (2008) Computer navigation versus con-
ventional implantation for varus knee total arthroplasty: a case-
control study at 5 years follow-up. Knee 15(2):75–79
34. Perlick L, Bathis H, Lerch K, Luring C et al (2004) Navigated
implantation of total knee endoprostheses in secondary knee
osteoarthritis of rheumatoid arthritis patients as compared to
conventional technique. Z Rheumatol 63(2):140–146
35. Picard F, Deakin AH, Clarke JV, Dillon JM et al (2007) Using
navigation intraoperative measurements narrows range of out-
comes in tka. Clin Orthop Relat Res 463:50–57
36. Pitto RP, Hamer H, Fabiani R, Radespiel-Troeger M et al (2002)
Prophylaxis against fat and bone-marrow embolism during total
hip arthroplasty reduces the incidence of postoperative deep-vein
thrombosis: a controlled, randomized clinical trial. J Bone Joint
Surg Am 84-A(1):39–48
37. Rand JA, Trousdale RT, Ilstrup DM, Harmsen WS (2003) Factors
affecting the durability of primary total knee prostheses. J Bone
Joint Surg Am 85(2):259–265
38. Saleh KJ, Macaulay A, Radosevich DM, Clark CR et al (2001)
The knee society index of severity for failed total knee arthro-
plasty: practical application. Clin Orthop Relat Res 392:166–173
39. Seon JK, Park SJ, Lee KB, Li G et al. (2008) Functional com-
parison of total knee arthroplasty performed with and without a
navigation system. Int Orthop
40. Sharkey PF, Hozack WJ, Rothman RH, Shastri S et al (2002)
Insall award paper. Why are total knee arthroplasties failing
today? Clin Orthop Relat Res 404:7–13
41. Song EK, Seon JK, Yoon TR, Park SJ et al. (2006) Functional
results of navigated minimally invasive and conventional total
knee arthroplasty: a comparison in bilateral cases. Orthopedics 29
10 Suppl:S145–147
42. Sparmann M, Wolke B, Czupalla H, Banzer D et al (2003)
Positioning of total knee arthroplasty with and without navigation
support. A prospective, randomised study. J Bone Joint Surg Br
43. Spencer JM, Chauhan SK, Sloan K, Taylor A et al (2007)
Computer navigation versus conventional total knee replacement:
no difference in functional results at 2 years. J Bone Joint Surg Br
44. Stickles B, Phillips L, Brox WT, Owens B et al (2001) Defining
the relationship between obesity and total joint arthroplasty. Obes
Res 9(3):219–223
45. Stockl B, Nogler M, Rosiek R, Fischer M et al (2004) Navigation
improves accuracy of rotational alignment in total knee arthro-
plasty. Clin Orthop Relat Res 426:180–186
46. Stulberg B, Zadzilka J (2008) Navigation matters: initial expe-
rience with navigation for bilateral total knee arthroplasty. Tech
Knee Surg 7(3):166–171
47. Victor J, Hoste D (2004) Image-based computer-assisted total
knee arthroplasty leads to lower variability in coronal alignment.
Clin Orthop Relat Res 428:131–139
892 Knee Surg Sports Traumatol Arthrosc (2011) 19:887–892
... With the introduction of technical support such as robotics and navigation, it could be shown that the precision for leg alignment and balance is higher compared to the conventional technique [18,30]. Although revision rates are reduced in navigated TKA [6], only a few studies could demonstrate that an improved technical precision is also accompanied by increased patient satisfaction [20,29]. Other studies failed to prove a clinical difference [5,25]. ...
... Three options to overcome the problem of this non-anatomical cut of posterior lateral condyle exist: (1) Performing the tibia cut in more varus. (2) Leaving the lateral flexion gap larger than the medial and (3) a combination of 1 and 2. Option 1 is chosen in some tibia first alignment workflows, such as constitutional varus [20] or patient-specific technique (PST) [4]. By placing the tibia in more varus simultaneously the amount of external rotation needed to balance the flexion gap is reduced. ...
Purpose: Navigated, gap-balanced adjusted mechanical alignment (AMA) including a 0° varus tibial cut and modification of angles and resections of the femoral cuts to obtain optimal balance accepting minor axis deviations. Objectives of this study were (1) to analyse to what extent AMA achieves the goals for leg alignment and gap balance, and (2) in what percentage non-anatomical cuts are needed to achieve these goals. Methods: Out of 1000 total knee arthroplasties (TKA) all varus knees (hip-knee-ankle (HKA) angle < 178°; n = 680) were included. All surgeries were performed as computer assisted surgery (CAS) in AMA technique. CAS data at the end of surgery were analysed with respect to HKA and gap-sizes. All bone cuts were quantified. Depending on the amount of deformity, a subgroup analysis was performed. It was analysed whether the amount of deformity influences the non-anatomical cuts by correlation analysis. Results: AMA reached the goals for postoperative HKA (3° corridor) in 636 cases (93.5%). While extension and flexion gap balance were achieved in more than 653 cases (96%), flexion and extension gap size were equalled in 615 knees (90.4%). The resections of the lateral tibia plateau and distal and posterior medial femoral condyle were anatomical (Tibia: 7.0 ± 1.7 mm; medial condyle distal: 7.8 ± 1.4 mm; medial posterior: 8.2 ± 1.8 mm). The number of non-anatomical resections for those cuts were low; 67 (9.9%); 24 (3.5%); 32 (4.7%). For the medial tibia plateau and the lateral posterior condyle, the cuts were non-anatomical in a high percentage of cases; Tibia: 606 (89.1%), lateral posterior condyle: 398 (58.5%). Moderate but significant correlations were found between resection differences and amount of deformity (medio-lateral: tibia: 0.399; distal femur: 0.310; posterior femur: 0.167). No correlations were found between resection differences and gap values. Conclusion: AMA reaches the intended target for HKA and gap balance in over 612 (90%) of cases and maintains the medial femoral condyle anatomically. Non-anatomical tibial resection causes increased external rotation of the femoral component and by that non-anatomical cut of the posterior lateral condyle. Nonanatomical resections of AMA might be one reason for the persisting high rate of unsatisfied patients after TKA. Anatomical and individual alignment philosophies might help to reduce this rate of dissatisfaction.
... Results presented here add to literature supporting improved TKA results when a well-controlled RAS TKA workflow is performed. However, there are many studies both supporting CAS and RAS [27][28][29][30][31][32][33][34][35][36][37][38] as well as reporting no improvement compared to conventional surgery [5,6,[39][40][41][42][43][44][45][46]. The combination of a wide range of study types, patient populations, protocols and confounding factors results in conflicting literature without a clear clinical answer. ...
Full-text available
Introduction The impact of fulfillment of patient expectations throughout recovery on satisfaction in total knee arthroplasty (TKA) is not well understood. Utilizing a standardized TKA method with a robotically assisted (RA) platform, we investigated the impact of expectation fulfillment at 3-month (M) and 6-M on 1-year (Y) and 2-Y satisfaction. We hypothesize that early fulfillment of patient expectations is associated with improved midterm patient satisfaction. We also compare improvements in outcomes with RA-TKA to those of a recent large national TKA cohort study to determine whether RA-TKA meets or exceeds the current standard of care. Materials and methods One hundred six patients were prospectively enrolled and underwent robotic-assisted TKA by a single surgeon using the OMNIBotics system. Patients completed KOOS and New Knee Society Score (KSS) preoperatively and at 3M, 6M, 1Y, and 2Y postoperatively. Expectation fulfillment was subdivided into patients who were below or above the average expectation score pre-operatively, or fulfillment of expectation score at 3M and 6M post TKA. The satisfaction of each group was then compared at 1Y and 2Y post TKA. Study cohort outcomes were compared to contemporary literature from the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE–TJR) database. Results Patients with greater than average KSS expectation fulfillment at 3M reported significantly higher KSS satisfaction scores at 1Y (34.9 ± 5.3 vs 30.6 ± 6.7, p = 0.0012), and patients with greater than average 6M expectation fulfillment reported improved satisfaction at 1Y (33.9 ± 5.9 vs 31.1 ± 6.7, p = 0.0330) and 2Y (35.2 ± 4.8 vs 32.4 ± 6.8, p = 0.0323). When compared to the FORCE-TJR database, no significant differences in post-operative KOOS outcomes were observed except for Sports and Recreation, for which the RAS group demonstrated higher scores (65.5 ± 30.0 vs 53.0 ± 27.1 p < 0.0001); however, the study cohort reported significantly greater improvements in KOOS Pain, Symptoms, Sports and Recreation, and Quality of Life at multiple time points up to 2 years post TKA. Conclusion High early-expectation fulfillment was associated with improved satisfaction at 1Y and 2Y, indicating the importance of managing patient-specific post-operative care to ensure patients reach their pre-operative goals. Greater improvements in all KOOS sub-scores and in absolute Sports and Recreation at 1Y and 2Y were observed in this robotic-assisted cohort compared to a large contemporary database, indicating that RAS meets or exceeds current standard of care benchmarks for patient-reported outcomes.
... This can be challenging and causes surgeons to divert their visual focus and attention. It also leads to excess surgical time and is error-prone [8][9][10][11]. Furthermore, such a setup does not allow for careful data exploration by the surgeon during surgery, necessitating indirect data presentation by a second person. This indirect communication can compromise the results and may lead to a cumbersome sterilizing process, wastes time and endangers asepsis. ...
Full-text available
Background Oral and maxillofacial surgery currently relies on virtual surgery planning based on image data (CT, MRI). Three-dimensional (3D) visualizations are typically used to plan and predict the outcome of complex surgical procedures. To translate the virtual surgical plan to the operating room, it is either converted into physical 3D-printed guides or directly translated using real-time navigation systems. Purpose This study aims to improve the translation of the virtual surgery plan to a surgical procedure, such as oncologic or trauma surgery, in terms of accuracy and speed. Here we report an augmented reality visualization technique for image-guided surgery. It describes how surgeons can visualize and interact with the virtual surgery plan and navigation data while in the operating room. The user friendliness and usability is objectified by a formal user study that compared our augmented reality assisted technique to the gold standard setup of a perioperative navigation system (Brainlab). Moreover, accuracy of typical navigation tasks as reaching landmarks and following trajectories is compared. Results Overall completion time of navigation tasks was 1.71 times faster using augmented reality (P = 0.034). Accuracy improved significantly using augmented reality (P < 0.001), for reaching physical landmarks a less strong correlation was found (P = 0.087). Although the participants were relatively unfamiliar with VR/AR (rated 2.25/5) and gesture-based interaction (rated 2/5), they reported that navigation tasks become easier to perform using augmented reality (difficulty Brainlab rated 3.25/5, HoloLens 2.4/5). Conclusion The proposed workflow can be used in a wide range of image-guided surgery procedures as an addition to existing verified image guidance systems. Results of this user study imply that our technique enables typical navigation tasks to be performed faster and more accurately compared to the current gold standard. In addition, qualitative feedback on our augmented reality assisted technique was more positive compared to the standard setup.
... Patients with mild pre-operative OA were reported to have a worse prognosis in improvement in physical functioning [34,35], and therefore, it is difficult to meet their expectations post-operatively [35]. These effects are more noticeable in patients undergoing a TKR as compared with those who have (45) 2, 3, 4, 5, 10, 15,29,33,34,35,36,37,38,39,40,46,57,59,60,72,83,86,89,91,107,113,115,116,117,120,126,143,149,153,154,155,156,157,161,173,174,176,177,180,181 5 Grades (36) 7,11,16,17,18,20,21,22,30,31,41,43,45,47,49,56,58,61,62,68,85,90,94,95,104,111,125,135,138,148,150,151,159,162,164,171 6 Grades (6) Studies are described using serial numbers in Table 3. The number of studies in each group is shown in parentheses had a THR [34]. ...
Full-text available
Background Although total knee replacement (TKR) is an effective intervention for end-stage arthritis of the knee, a significant number of patients remain dissatisfied following this procedure. Our aim was to identify and assess the factors affecting patient satisfaction following a TKR.Materials and methodsIn accordance with the PRISMA guidelines, two reviewers searched the online databases for literature describing factors affecting patient satisfaction following a TKR. The research question and eligibility criteria were established a priori. Any clinical outcome study that described factors relating to overall satisfaction after primary TKR was included. Quality assessment for the included studies was performed by two accredited orthopaedic surgeons experienced in clinical research.ResultsThe systematic review identified 181 relevant articles in total. A history of mental health problems was the most frequently reported factor affecting patient satisfaction (13 reportings). When the results of the quality assessment were taken into consideration, a negative history of mental health problems, use of a mobile-bearing insert, patellar resurfacing, severe pre-operative radiological degenerative change, negative history of low back pain, no/less post-operative pain, good post-operative physical function and pre-operative expectations being met were considered to be important factors leading to better patient satisfaction following a TKR.Conclusion Surgeons performing a TKR should take these factors into consideration prior to deciding whether a patient is suitable for a TKR. Secondarily, a detailed explanation of these factors should form part of the process of informed consent to achieve better patient satisfaction following TKR. There is a great need for a unified approach to assessing satisfaction following a TKR and also the time at which satisfaction is assessed.
Background In total knee arthroplasty (TKA), computer-assisted navigation (N-TKA) and robotic-assisted methods (RA-TKA) are intended to increase precision of mechanical and component alignment. However, the clinical significance of published patient reported outcome measure (PROM) differences in comparison to conventional TKA (C-TKA) is unknown. Methods A systematic review was performed to identify all studies reporting perioperative PROMs for either primary N-TKA or RA-TKA with a C-TKA comparison cohort with minimum one-year follow up. Relative improvements in PROMs for the two cohorts was compared to published minimal clinically important difference (MCID) values. Results After PRISMA analysis, 21 studies (N=3,214) reporting on N-TKA and eight studies (N=1,529) reporting on RA-TKA met inclusion criteria. Eighteen of 20 studies (90%) reported improved radiographic outcomes with N-TKA relative to C-TKA; five out of five studies reported improved radiographic outcomes with RA-TKA relative to C-TKA. Five of 21 studies (24%) reported statistically significant greater improvements in clinical PROMs for N-TKA relative to C-TKA, while only two (10%) achieved clinical significance relative to MCID on secondary analysis. One of 8 studies (13%) reported statistically significant greater improvements in PROMs for RA-TKA relative to C-TKA, while none achieved clinical significance relative to MCID on secondary analysis. No studies reported significant difference in revision rates. Conclusion While most studies comparing RA-TKA and N-TKA with C-TKA demonstrate improved radiographic alignment outcomes, a minority of studies reported PROM differences that achieve clinical significance. Future studies should report data and be interpreted in the context of clinical significance to establish patient and surgeon expectations for emerging technologies.
Background Although computer navigation has improved component alignment in total knee arthroplasty (TKA), radiographic outliers are reported with a wide range in literature even using this technique. We hypothesized that the postoperative malalignment after computer-navigated TKA was partially derived from the inherent problems with two-dimensional (2D) measurement such as inaccuracies in measurement due to the knee position during the radiographic examination and the direction of the X-ray beam. We therefore conducted this study to determine how often knees with malalignment on 2D imaging were truly mal-aligned on three-dimensional (3D) reconstructed imaging. Methods Sixty-two computer-navigated primary TKAs performed in 47 patients were included in this study. In all cases, a weight-bearing long-leg radiograph was obtained after TKA. 3D measurements were performed for outliers 2° or more in coronal alignment of the femoral or tibial component. Results For the 18 femoral mal-aligned components on 2D imaging, eight (44.4%) were not truly mal-aligned on 3D imaging (P = 0.0014). For the eight tibial mal-aligned components on 2D imaging, all knees (100%) were not truly mal-aligned on 3D imaging (P < 0.0001). Conclusions A considerable number of the false malalignments were included on 2D measurement. Postoperative component alignment in the computer-navigated TKA might be much better than previously reported.
Objective In obese patients, thick subcutaneous tissue can introduce errors during registration and leg weight can influence gap balancing in navigated TKA. Present study is done to determine if computer navigation with gap balancing technique can provide consistent accuracy for limb and component alignment and similar functional results in obese subgroup of patients like in non-obese patients. Methods We prospectively compared the radiological, clinical, and functional results of 78 knees in 57 non-obese patients and 79 knees in 58 obese patients who underwent computer-assisted TKA. Non-obese individuals were defined as those having BMI of <30 kg/m² and obese individuals as BMI ≥30 kg/m². The degree of knee deformity was calculated by Hip – Knee – Ankle (HKA) angle and clinical and functional assessment was done using the Knee Society Score – clinical knee score and Knee Society Score - function score, respectively. All these were documented before and at 6 months, 2 year, and 5 years after TKA. Results The outlier rate of postoperative limb alignment (HKA angle) was 8.9% in the obese group which was not significantly different from that of the non-obese group (7.7%). Mean clinical knee scores were not significantly different between the non-obese and obese groups both before (58.8 vs 57.4, p = 0.14) and at 6 months (92.7 vs 91, p = 0.06), 2 years (91.4 vs 90, p = 0.07), and 5 years (92.4 vs 91.3, p = 0.1) post-surgery. Similarly, Mean functional scores were not significantly different between the non-obese and obese groups both before (50.9 vs 49.9, p = 0.31) and at 6 months (92.7 vs 90.9, p = 0.06), 2 years (91.3 vs 92, p = 0.44), and 5 years (90.6 vs 91.1, p = 0.51) post-surgery. Conclusion Obesity has no influence on mid-term clinical, functional, and radiological results after computer navigated TKA, done by gap balancing technique. Level of evidence Therapeutic level II.
The study is a systematic review and meta-analysis of prospective randomised control studies and prospective cohort studies of mid-term functional outcome of total knee replacement undertaken using imageless computer navigation compared with conventional instrumented total knee replacement. The literature search strategy included a search of the electronic databases, visual scanning of reference lists, hand searching of key journals and conference proceedings, and abstracts, citations, and trial registers. In total, 440 papers were retrieved after removal of duplicates, and with further screening, 11 papers were included in the systematic review and 6 papers were considered appropriate for meta-analysis. Analysis of the data showed evidence of a modest improvement in functional outcome at mid-term follow-up with use of imageless computer navigation assistance compared with conventional instrumented total knee replacement with a total score point estimate of 3.36 confidence interval (CI) (− 0.583, 7.298), objective score point estimate of 1.45 CI (0.11, 2.799), and functional score point estimate of 2.4, CI (− 1.174, 5.977). The predominant risk of bias was from random allocation and attrition. There is evidence of a modest improvement in functional outcome with the use of imageless computer navigation assistance compared with conventional instrumented total knee replacement at mid-term follow-up.
Full-text available
Total knee arthroplasty (TKA) is a successful and cost-effective treatment for end-stage degenerative arthritis. The aging of society and an increase in the prevalence of obesity has led to increases in the prevalence of arthritis and the incidence of TKA. Currently, the total number of procedures in Korea per year has reached 90,000. With the rapid growth, we need to know about the current state of TKA. The purpose of this review is to summarize the recent literature regarding TKA. The main indication for TKA is end-stage arthritis with severe pain, reduced function, and no response to conservative management. Metal on the polyethylene-bearing surface and cobalt alloy are used in most TKAs. Despite good clinical outcomes and long-term survival rates after TKA in many papers, 20% of patients are dissatisfied with the outcome of surgery. To improve the patient’s satisfaction, surgeons should understand factors affecting patient’s satisfaction, including patient’s expectations, age, and preoperative mental state. Navigation-assisted surgery and robotic surgery have been introduced in knee arthroplasty to achieve more precise and accurate alignment. There is some evidence to suggest that computer-assisted surgery reduces revision rates. However, clinical efficacy is also controversial, and a long-term follow-up study is required. The common complications of TKA include infection, polyethylene wear, loosening, stiffness, periprosthetic fracture, and thromboembolism. An understanding of the potential complications and pitfalls of TKA is essential for prevention.
We cannot deny that technology has become an important part of our daily life, not only in automobiles, houses or cellphones but also in hospitals. In the OR, in particular for knee arthroplasty, image free navigation has proven to reduce the number of outliers and by that the revision rate in younger patients. Over the last years robotics has again been introduced into the operation theatres. However, in their present version they add time and costs, but only minimal benefits to the procedure. Therefore, future robots should be faster and instrumentation free. Beside those more economical aspects, the goal of this digital technology must be an improvement in clinical outcome. To achieve that, additional steps for analyzing the pre-, and intra-OP quantitative data is key. With the use of artificial intelligence and/or machine learning a data based algorithm will probably be developed, which helps the surgeon to integrate all parameters into his individual cutting and releasing plan for each patient. Digital data therefore, might become the key to enable the surgeon to treat patients more individual and by that hopefully deliver better outcome.
Full-text available
A cross-sectional, community-based survey of a random sample of 1750 of 242,311 Medicare recipients was performed. The patients were at least sixty;five years old and had had a primary or revision knee replacement (either unilaterally or bilaterally) between 1985 and 1989. Three samples were surveyed separately: a national sample (to reflect the United States as a whole) and samples from Indiana and the western part of Pennsylvania (sites chosen for convenience to assess the validity of the findings for the national sample on a regional level). Each sample was stratified by race, age, residence (urban or rural), and the year of the procedure. Valid and reliable questionnaires were used to elicit the participants' assessments of pain, physical function, and satisfaction two to seven years after the knee replacement. Of the 1486 patients who were eligible for inclusion in the survey, 1193 (80.3 per cent) responded. The mean age of the respondents was 72.6 years, Eight hundred and forty-nine respondents (71.2 per cent) were white, and 849 (71.2 per cent) were women. The participants reported that they had;little or no pain in the knee at the time of the survey, regardless of the age at the time of the knee replacement, the body-mass index, or the length of time since the knee replacement. After adjustment for potential confounding variables, predictors of better physical function after the replacement were an absence of problems with the contralateral knee, primary knee replacement (rather than revision) (Indiana sample only), and a lower body-mass index (Indiana and western Pennsylvania samples). Four hundred and fifteen (85.2 per cent) of the 487 patients in the national sample were satisfied with the result of the knee replacement, In what we believe to be the first community-based study of the outcome of knee replacement, patients reported having significant (p = 0.0001) and persistent relief of pain, improved physical function, and satisfaction with the result two to seven years postoperatively. The findings of the present study suggest that age and obesity do not have a negative impact on patient-relevant outcomes (pain and physical function), Dissemination of these findings has the potential to increase appropriate referrals for knee replacement and thereby reduce the pain and functional disability due to osteoarthrosis of the knee.
Full-text available
Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA. In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films. The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within ±3° varus/valgus) compared with the conventional group (78%, within ±3° varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group. Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.
Conference Paper
Posterior cruciate ligament-substituting total knee prostheses have been used extensively since the original posterior-stabilized condylar prosthesis was introduced more than 2 decades ago. The key design principle of this prosthesis was the incorporation of a cam and post mechanism on the femoral and tibial components. This mechanism was intended to function as a mechanical substitute for the posterior cruciate ligament, to optimize prosthesis roll back in flexion, and to avoid flexion instability by preventing posterior subluxation. Central to the use of these devices was the surgical technique, which required resection of both cruciate ligaments and creation of symmetric flexion and extension gaps with equal medial and lateral soft tissue tension. Modifications to the original design have been introduced gradually; these include changes to the patellofemoral geometry, and the addition of monoblock and modular metal-backed tibial components. Despite these changes, the key concepts of the prosthesis design and surgical technique have remained constant. The clinical results obtained with the use of these designs have been reported extensively. Long-term results at greater than 10 years continue to duplicate the outstanding early results with prosthesis survivorship exceeding 95% and high levels of patient function.
We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients randomly allocated to receive either of the methods. Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken. Intra-operative and peri-operative morbidity data were collected and blood loss measured. Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus (p = 0.032), femoral rotation (p = 0.001), tibial varus/valgus (p = 0.047) tibial posterior slope (p = 0.0001), tibial rotation (p = 0.011) and femorotibial mismatch (p = 0.037). Standing alignment was also improved (p = 0.004) and blood loss was less (p = 0.0001). Computer-assisted surgery took longer with a mean increase of 13 minutes (p = 0.0001).
Computer-assisted surgery (CAS) has become established in many hospitals throughout the world, especially in the form of computer navigation for total knee replacement (TKR). Analysis of the studies available revealed 18 comparative studies examining the precision of implantation of knee endoprostheses following CAS and after implantation by the conventional technique. In a meta-analysis of 13 studies in which the same safe zone of ±3 from neutral alignment was defined for the leg axis, a total of 1,784 TKR were performed. In the group of patients in whom the conventional technique was used, 75.6% (654/865) of TKR were implanted within the safe zone. In the CAS group 93.9% (863/919) of the prostheses were implanted within the safe zone (p<0.0001). The differences between the groups were statistically significant in 11 of the 13 studies, and the difference between groups for the entire patient population is highly significant. Only limited clinical results were ascertained in these comparative studies; there were no great differences between the treatment groups in clinical course.
Objective: The purpose of this study was to examine the relationship between obesity and patient-administered outcome measures after total joint arthroplasty. Research Methods and Procedures: A voluntary questionnaire-based registry contained 592 primary total hip arthroplasty patients and 1011 primary total knee arthroplasty patients with preoperative and 1-year data. Using logistic regression, the relationships between body mass index and the several outcome measures, including Short Form-36 and Western Ontario and McMaster Universities Osteoarthritis Index, were examined. Results: There was no difference between obese and non-obese patients regarding satisfaction, decision to repeat surgery, and Δphysical component summary, Δmental component summary, and ΔWestern Ontario and McMaster Universities Osteoarthritis Index scores (p > 0.05 for all). Body mass index was associated with an increased risk of having difficulty descending or ascending stairs at 1 year (odds ratio, 1.2 to 1.3). Discussion: Obese patients enjoy as much improvement and satisfaction as other patients from total joint arthroplasty.
This article provides an overview of the rationale for computer-assisted surgery and the technical aspects of navigation for total knee arthroplasty. The authors' experience with computer-assisted surgery for total knee arthroplasty using the VectorVision (BrainLAB, Feldkirchen, Germany) and Ci (DePuy, Warsaw, Ind) system to assist in mobile bearing total knee arthroplasty, the validation of the technique, and outcomes from a series of more than 1000 consecutive cases are reported.
The purpose of this study was to evaluate the effectiveness and safety of surgical navigation for sequential bilateral total knee arthroplasty (TKA) in a single anesthetic session. We retrospectively evaluated our initial experience with navigated bilateral TKA to determine if benefits of improved consistency of implantation, decreased blood loss, and reduced systemic emboli could be identified. Two groups were compared. The investigational group had bilateral TKA using surgical navigation, and the control group had bilateral TKA using conventional instrumentation. Knee Society Scores were used for clinical evaluation and component placement, and alignment was determined using the Knee Society Radiological Evaluation protocol. Complications were similar in both groups. Alignment was significantly better in the navigation group, and time of surgery was significantly longer. Three knees (1 navigated, 2 control) required additional surgery for late infection. In addition, there were 3 revisions for mechanical failure. All of these were in the control group and could be related to either malalignment or instability. These technical factors were better addressed with navigation. Safety was not compromised, and results suggest that the use of surgical navigation will have an impact on component survivorship.
Background Navigated implantation of total knee prostheses has become more and more popular within the last decade in orthopaedic surgery. Although improved alignment after navigated knee surgery has been reported previously in the literature, only a few studies meet the criteria of a level-1 evidence-based medicine study. We present the results of a controlled and prospective study comparing early clinical outcomes after computer-assisted versus conventional implantation in total knee arthroplasty (TKA). Methods Within a 15-month period, all patients admitted for primary TKA were followed prospectively. Each patient was evaluated using the Knee Society Score (KSS) preoperatively, 10 days after surgery, and 3 months after surgery. The patients were divided into two groups, and the implantation technique altered between the two treatment options: each conventional implantation was strictly followed by a computer-assisted procedure and vice versa. Results From March 2003 to June 2004, we did 34 computer-assisted (group A) and 35 conventional knee arthroplasties (group B) in 62 patients. There was no difference in the preoperative status of the patients. Surgeries in group A took significantly longer than in group B. The average deviation from correct alignment was significantly reduced in group A. 66 of 69 of the TKAs were available for follow-up examinations after 10 days and after 3 months. No significant differences were found in the overall KSS scores or in the subgroups. Conclusions The intraoperative use of a computer-assisted navigation system during implantation of a total knee prosthesis reduced the average varus/valgus deviation from the anatomical long leg axis. A disadvantage of the computer-assisted surgical procedure may be the longer operating time. Long-term follow-up of the presented data is needed in order to show whether the improved average alignment is advantageous for patients and/or results in a longer service life of the TKA.