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DOI: 10.1302/2058-5241.5.200037
www.efortopenreviews.org
Robotic systems used in orthopaedics have evolved from
active systems to semi-active systems.
Early active systems were associated with significant tech-
nical and surgical complications, which limited their clini-
cal use.
The new semi-active system Mako has demonstrated
promise in overcoming these limitations, with positive
early outcomes.
There remains a paucity of data regarding long-term out-
comes associated with newer systems such as Mako and
TSolution One, which will be important in assessing the
applicability of these systems.
Given the already high satisfaction rate of manual THA,
further high-quality comparative studies are required uti-
lizing outcome scores that are not limited by high ceiling
effects to assess whether robotic systems justify their addi-
tional expense.
Keywords: complications; outcomes; robotic-assisted; total
hip arthroplasty
Cite this article: EFORT Open Rev 2020;5:866-873.
DOI: 10.1302/2058-5241.5.200037
Introduction
Background
Long-term outcomes and survivorship of total hip arthro-
plasty (THA) are dependent on the accurate restoration
of hip biomechanics, which is achieved through optimal
component positioning.1–9 It is evident that suboptimal
component positioning leads to joint instability,9 increased
wear,10 and poorer function.11–14 Robotic-assisted ortho-
paedic surgery has the potential to improve the accu-
racy of component positioning in THA, thus, enhancing
clinical outcomes.15,16 This review aims to summarize the
history and development of robotic technology in ortho-
paedic surgery, and discuss the evidence base surround-
ing its use.
Evolution of robotic surgery in orthopaedics
There has been an increased uptake of robotic surgery
across different specialties since it was first introduced for
neurosurgical biopsies in 1985.17 In orthopaedics, robotic
systems are classified as passive, active (autonomous) or
semi-active (haptic); of which, the latter two are most
commonly used. With passive robotic systems, the sur-
geon retains control of the robot throughout the proce-
dure. The da Vinci robot is one such example, although
its use has been limited to upper limb orthopaedic pro-
cedures.18 Early robotic systems for THA were based on
active technology, where the robot operated autono-
mously under surgical supervision without real-time guid-
ance.19 The robot was programmed using pre-operative
computed tomography (CT) to carry out bony prepara-
tion for component implantation once adequate surgical
exposure was achieved intra-operatively. An instant shut-
off switch was available to the surgeon if required.15 In
recent years, semi-active robotic systems have become
increasingly popular.15,20 These systems require the sur-
geon to guide the robotic arm for bony preparation via a
haptic feedback mechanism that ensures minimal devia-
tion from the pre-determined surgical plan. Additionally,
these systems have the capability to provide real-time
information on femoral preparation to allow corrections
to be made intra-operatively.
First-generation robotic systems
ROBODOC
ROBODOC (Curexo Technology Corporation, Fremont,
California, USA) was an active robotic system and the first
robotic system used in THA.21 Since its inception, it has
Robotics in total hip arthroplasty: a review of the
evolution, application and evidence base
Jean-Pierre St Mart1
En Lin Goh2
Zameer Shah3
5.2000EOR0010.1302/2058-5241.5.200037
review-article2020
Hip
867
Robotics in total hip aRthRoplasty
been used in over 17,000 procedures.22 As part of the pre-
operative phase, a CT scan of the patient was uploaded
to the ORTHODOC workstation software to generate a
three-dimensional (3D) virtual model of the patient’s
anatomy. This was used to plan and select the optimal
design and size of the femoral component based on fit
and fill for each patient.20 The customized plan would
then be transferred to the ROBODOC surgical system
consisting of a five-axis robotic arm with a high-speed
milling device.21 Post calibration and ‘matching’ of the
pre-operative plan to the patient’s anatomy, the robotic
arm would then be used to mill out the proximal femur
to accommodate the press fit femoral stem. Since this
was a fully active system, once initiated, the only input
allowed by the surgeon was an emergency stop. The ace-
tabulum would then be manually reamed and standard
instrumentation used for component implantation. Sev-
eral modifications were made throughout its lifespan to
address early complications associated with the original
pin-based calibration system,21,23 which required inser-
tion into the femur.24,25 In 2004, the holding company,
Integrated Surgical Systems became financially insolvent
after facing a class action lawsuit over complications
associated with the system and was acquired by Curexo
Technology Corporation.
CASPAR
CASPAR (Universal Robotic Systems Ortho, Germany) was
an active robotic system that utilized similar pre-operative
CT planning to ROBODOC to mill the proximal femur
and guide implant insertion. This system had several
prevailing issues; notably, variable precision of implan-
tation and poorer post-operative outcomes,26–29 which
highlighted the challenges associated with early robotic
systems. This system is no longer in used since Universal
Robotic Systems Ortho, the company behind it, went out
of business.30
ACROBOT
ACROBOT (The Acrobot Co. Ltd, London, UK) was devel-
oped with the aim of addressing issues associated with
ROBODOC and CASPAR.19 As with the aforementioned
systems, pre-operative CT-based software was used to cre-
ate a surgical plan. This was then mapped to the patient’s
anatomy using a non-invasive anatomical registration
method with the robotic arm subsequently guided by the
surgeon to perform bony resection under haptic feed-
back.31 This system was advantageous as it could achieve
the same level of accuracy as its predecessors without a
significant time delay.32 This system was sold to Stanmore
Implants Worldwide and the technology was purchased
by Mako as part of a confidential patent infringement set-
tlement in 2013.19
New-generation robotic systems
Mako
Mako (Stryker Corporation, Kalamazoo, MI, USA) is a
semi-active robotic system that has been used in more
than 20,000 THAs.15,33,34 Similar to earlier systems, pre-
operative CT imaging is used to generate a 3D model of
the native hip joint. An initial plan is created using selected
CT landmarks and superimposed onto the 3D reconstruc-
tion. The surgeon is then able to fine-tune this to ensure
optimal templating of component size and alignment,
thus allowing the desired restoration of hip biomechanics,
bone coverage, component positioning and leg-length
correction.15 In contrast to earlier systems, the robotic
arm is not fully automated but based on haptic feedback,
so the surgeon retains partial control. There are cur-
rently two Mako software paths available: the enhanced
and express femoral workflows. The enhanced workflow
requires the full mapping and matching of both the proxi-
mal femur and acetabulum to the pre-operative 3D plan.
This is performed by the registration of 32 surface points
on both the acetabulum and femur, making it possible to
calculate offset and hip length throughout the operation
via pelvic and greater trochanteric checkpoints. For this
workflow, initial femoral canal preparation and measure-
ment of stem version allows subsequent adjustment of
planned acetabular component positioning prior to ream-
ing and cup placement. This is based on the theory of
combined version as described by Ranawat and Dorr.35,36
Although the femur is prepared manually, the level of the
neck cut can also be marked as indicated by the Mako
software prior to resecting. For acetabular preparation,
the surgeon reams using the robotic arm guided by hap-
tic feedback. This prevents the surgeon from straying from
the surgical plan. The same haptic-guided robotic arm is
used to implant the acetabular component with the Mako
software monitor displaying real-time information thus
ensuring the cup is well seated. This ensures that over-
reaming is restricted to 2.3 mm and cup orientation to
within 5° of the surgical plan.34 The express workflow uses
the robotic arm for acetabular preparation only but allows
limb-length discrepancy and offset to be calculated with
similar accuracy to the enhanced workflow using similar
pelvic and femoral checkpoints.
TSolution One
TSolution One is an active robotic system that incorpo-
rated the technology developed for ROBODOC. In addi-
tion to active femoral canal preparation, this system
provides guided acetabular reaming and assisted cup
implantation with the robotic arm. This system has since
gained FDA approval, although the effectiveness of this
system is yet to be determined due to the lack of available
studies.19,37
868
Operating system platforms
Open platforms
ROBODOC and CASPAR were open platforms. This meant
that they provided compatibility with different implant
companies and designs, which enabled the surgeon to
tailor implant choice to the patient’s anatomy. However,
the capability of the open platform to incorporate con-
figurations for multiple implant choices resulted in a lack
of design specificity and biomechanical data to predict
optimal implant positioning.30,38
Closed platforms
Mako is a closed platform, which currently limits the ace-
tabular component to the Trident cup and the stem choice
to either the cemented Exeter or uncemented Accolade II
stem (Stryker, Mahwah, New Jersey, USA). As such, sur-
geons may have to use an alternative implant compared
to their usual practice. As the long-term outcomes relat-
ing to this system become clearer, surgeons will need to
decide whether the risks and benefits of such a robotic sys-
tem outweigh those associated with implant choice.33,39
Component positioning
There is a growing body of evidence that robotic THA sys-
tems improve component alignment.15 Previous active
systems have focused on femoral canal preparation using
a robotic milling arm prior to manual insertion, whilst
more recent semi-active systems such as Mako favour
acetabular preparation and insertion using a robotic arm
incorporating haptic feedback. In addition, the enhanced
workflow capability offers the option of optimizing com-
bined version as described above.34,36,40
Femoral side
Bargar et al noted that the ROBODOC group had signifi-
cantly better stem positioning compared to the manual
group,21 which has also been confirmed by other stud-
ies.23,41,42 Furthermore, manual THA was associated with
greater deviation in femoral anteversion from the pre-
operative plan, which correlated weakly with higher
vertical seating of the stem and increased risk of femoral
fracture. Cadaveric and lab-based studies of CASPAR have
suggested improved accuracy of femoral preparation over
a manual approach, although this may be influenced by
the type of stem used.43–46 However, the effectiveness of
CASPAR in a clinical environment has been questioned.
One study showed a significantly lower accuracy of post-
operative femoral stem anteversion compared with pre-
operative planning.29 This highlights the importance of
correlating experimental data with clinical outcomes,
when appraising new technology. Although the Mako
system relies on manual femoral broaching, the enhanced
femoral workflow path allows intra-operative calculation
of the trial femoral stem version. This allows femoral stem
retroversion to be detected and corrected towards a tar-
get of 15° anteversion if required.47
Acetabular side
Several studies have evaluated Mako’s ability to improve
placement of the acetabular component. This has been
based on previous studies noting the Lewinnek safe
zones and subsequent Callanan modification as essential
parameters for successful THA.9,48 Illgen et al reviewed
300 manual and robotic-assisted THAs.49 In their study,
the robotic group had improved acetabular component
placement within the Lewinnek safe zones compared
to the manual group. Subsequent studies have demon-
strated a higher likelihood of placement of the acetabular
component within the Lewinnek and Callanan safe zones
with Mako.50–52
Preservation of bone
Given the rising incidence of revision arthroplasty, bone
stock preservation is an important consideration in primary
THA.20 Short stems are advantageous over long stems as
they conserve more bone, thus providing more favour-
able conditions for future revision.53 However, meticulous
preparation of the femoral canal is required due to the
lack of diaphyseal fit in order to reduce the risk of stem
malalignment, incorrect stem sizing, and intra-operative
fracture.54 One advantage of the ROBODOC was its com-
patibility with short metaphyseal-fitting stems. A cadaveric
study by Lim et al noted improved fit, better seating and
a reduced risk of intra-operative fracture with ROBODOC
compared to manual rasping.55 This was corroborated by
a clinical study which confirmed more accurate implan-
tation of short femoral stems using ROBODOC’s milling
system compared to manual methods.56 Preservation of
acetabular bone stock in primary THA is essential in ensur-
ing proper stability of cementless acetabular components
as well as for considering future revision surgery.57,58 The
haptic feedback of the Mako robotic arm ensures acetabu-
lar over-reaming is restricted to no more than 2.3 mm of
the pre-operative CT plan.34 A study by Suarez-Ahedo et al
suggested that this accuracy led to a greater preservation
of bone stock compared to conventional THA.58
Limb-length discrepancy
Limb-length discrepancy (LLD) is associated with patient
dissatisfaction and is the most common reason for litiga-
tion after THA.59,60 The ability of robotic systems to poten-
tially minimize LLD is advantageous. A ROBODOC study
noted that LLD was significantly reduced in THAs where
the femoral canal was prepared with robotic assistance
compared to being manually rasped. This was despite the
869
Robotics in total hip aRthRoplasty
manual implantation of all femoral stems.23 A prospective
study by Nakamura et al with a minimum five-year follow-
up noted that, although there was no significant differ-
ence in LLD between the ROBODOC-assisted (75 hips)
and hand-rasped THAs (71 hips), the ROBODOC group
had significantly less variance in LLD.41 Furthermore, Lim
et al noted significantly smaller LLD with ROBODOC com-
pared to manual THA.56
Although a cadaveric THA study has demonstrated
the accuracy of measurement of leg lengths using Mako
software compared to CT scans,61 there are still questions
about whether this extrapolates to a reduction in LLD or
planned limb-length correction compared to traditional
techniques. Kayani et al noted that the Mako was more
accurate at restoring the patient’s native centre of rota-
tion and offset, but there was no difference in planned
limb-length correction compared to manual THA.62 Two
recent systematic reviews concluded no significant dif-
ference in limb-length discrepancy between robotic and
manual THR.63,64
Clinical outcomes
Functional outcomes
There is a limited amount of data evaluating functional
outcomes including patient-reported outcome measures
(PROMs) for robotic THA. Most data available are based on
active robotic systems which are now obsolete. For ROBO-
DOC, the majority of studies reported similar functional
outcome scores between robotic THA and manual THA
after three years of follow-up.21,23,25,56 However, Nakamura
et al noted marginally improved Japanese Orthopaedic
Association scores in the robotic THA group compared to
the manual THA group at two and three years follow-up,
although this was not sustained after five years.41 A long-
term study of patients undergoing surgery with ROBO-
DOC by Bargar and colleagues found that the robotic
THA group had significantly improved pain and function
scores compared to the manual THA group. There were
no significant differences in wear or revisions for loosen-
ing noted.22 One study evaluated the effectiveness of CAS-
PAR compared to the conventional techniques.28 In this
study, the authors reported similar Harris Hip Scale (HHS)
and Health Status Questionnaire (HSQ) scores between
the two groups after 18 months of follow-up. However,
the Merle d’Aubigné–Postel score was significantly less,
and hip abductor function significantly poorer in the
CASPAR group. More recently, several studies have evalu-
ated outcomes associated with the Mako robotic system.
Perets et al documented improvements in function, pain
and patient satisfaction scores with this system after two
years.65 These findings were supported by a subsequent
study comparing Mako and manual THAs, which showed
significantly better functional scores with Mako.3
Complications
A prevalent issue with robotic-assisted THA has been the
high rate of technical complications resulting in conver-
sion to the manual approach.23,25 Two studies estimated
that technical complications associated with ROBODOC
were as high as 18%.23,25 A recent study of Mako reported
technical complications in 1.4% of cases,50 which may
suggest improvements in the reliability of newer robotic
systems. Nevertheless, it is evident that technical issues
such as pelvic array loosening, acetabular registration
failure, repetitive reaming, and arduous cup implanta-
tion occur more frequently during the learning phase,
which has important implications for training.52 Another
important complication to consider is the rate of disloca-
tions. Honl et al reported that the ROBODOC group had
a significantly higher dislocation rate than the manual
group at 18%.23 Meanwhile, Nakamura et al documented
a similar rate of dislocations between the ROBODOC and
manual groups, which was attributed to better retraction
and preservation of the hip abductors.41 Illgen et al noted
dislocations were significantly reduced using Mako (0%)
compared to manual THA.49 Several studies of ROBODOC
have suggested that robotic THA may confer an advan-
tage in reducing the risk of intra-operative fracture.21,41
This can be attributed to greater accuracy of femoral
canal preparation by milling the proximal femur using the
robotic arm rather than manually rasping. Several stud-
ies have reported a higher rate of heterotopic ossification
associated with ROBODOC and CASPAR.28,41 Data regard-
ing intra-operative blood loss are inconclusive. Siebel et al
noted that there was significantly greater blood loss with
CASPAR.28 Subsequently, Illgen et al found that blood loss
was significantly lower with Mako.49 In terms of compo-
nent positioning, Kong et al reported unacceptable cup
positioning, LLD and offset in 10% of cases.52 Other less
common robotic complications that have been described
in the literature include nerve injury, infections and femo-
ral fissures.23,28 A systematic review compared the com-
plication rate of five robotic studies with manual THA.63
The five studies reviewed related to the ROBODOC and
CASPAR systems only. They noted a higher intra-operative
complication rate but a similar post-operative complica-
tion rate in manual compared to robotically assisted THA.
Overall complication rates were higher in the manual
THA group. A more recent meta-analysis including Mako
results also noted that robotic THA had less frequent intra-
operative complications but more post-operative disloca-
tions and revisions compared to manual THA.64 Overall,
there were no differences between the groups in terms
of total number of complications. The authors noted a
possible trend of reduction in complications with newer
robotic-assisted THA systems such as Mako and improved
surgical technique. However, the higher rate of technical
issues during the learning phase with all systems highlights
870
the importance of having a surgeon with sufficient hip
arthroplasty experience overseeing the procedure.
Clinical application
Learning curve
The learning curve is defined as the rate of a surgeon’s
progress in gaining experience or new skills.66 This is typi-
cally described as the number of cases needed to achieve a
steady state of outcomes. A variety of surrogate outcomes
have been used to assess the learning curve associated
with robotic THA including operating time, component
positioning and intra-operative complications. Earlier
studies evaluating the ROBODOC system have reported
mixed results. While Bargar et al and Nakamura et al sug-
gested that a significant learning curve was present,21,41
Honl et al subsequently refuted this.23 It is important to
emphasize that the contrasting findings from earlier work
may be due to differences in study design and sample
size. Recent studies evaluating the Mako system sug-
gest a learning curve of 12–35 cases based on operating
time.52,67,68 However, there is also substantial evidence
that there is no learning curve with regard to component
positioning with this system.52,68 It would therefore be
reasonable to conclude that the learning curve associ-
ated with newer robotic systems for THA is more closely
related to the familiarity of the surgical team with such
technology.
Cost-effectiveness
Robotic technology is associated with high front-end
costs, which include the robotic system, operational
costs, disposables, pre-operative imaging, and implants.20
These costs vary widely and are dependent on choice of
system, manufacturer license agreements and individually
negotiated pricing structures primarily based on each hos-
pital’s surgical volume. When first introduced, the ROBO-
DOC system price offering varied between US$635,000
and $1.5 million. In some cases this cost is subsidized by
implant manufacturers in order to increase sales of their
implants.69 The annual maintenance fees for most robotic
systems is between $40,000 and $150,000.70 This poten-
tially includes software upgrades which can otherwise
be an extra financial burden. Alternative payment struc-
tures include leasing models on a case-by-case payment
structure. Charges are then based on company-specific
implants and disposables required per case. The costs of
disposables alone can vary from $750 to $1300.70,71 In
addition both active and semi-active systems require pre-
operative CT scans which are an additional $260 each.70
The cost of implants has previously been estimated to rep-
resent between 15% and 87% of surgical costs without
taking into consideration additional expenses of robotic
technology.72 There is also likely to be significant variation
between open and closed platforms, the latter potentially
having increased pricing due to a lack of competition.
Chen et al recently analysed the increased cost associated
with robotic systems compared to manual THA.70 They
noted that using the Mako system added 12.2% and 6.1%
respectively to the cost of each THA if 100 and 300 cases
were performed, assuming a five-year robotic system life
span. Under the same pricing structure, they suggested
similar figures of 13.9% and 6.6% for 100 and 300 THAs
respectively performed with TSolution One robot. Poten-
tial financial burdens to offset the cost of robotic tech-
nology include the costs saved on revision surgery and
readmission for post-operative complications. For robotic
TKA surgery the readmission rate has been reported to
be a 5% lower than for conventional techniques.71 Chen
et al equated this to a 4% decrease in overall cost of pri-
mary TKA using a robotic system compared to traditional
instrumentation.70 However, studies regarding robotic
THA have been less favourable, with higher revision and
similar post-operative complication rates having been
reported.21,23 Chen et al equated this to a 20.3% increase
in cost when using robotic THA compared to manual
techniques.70
Discussion
Early active robotic systems focusing on femoral canal
preparation demonstrated theoretical advantages in terms
of better fit and potentially lower iatrogenic fracture rate
for uncemented stem implantation. However, improved
stem fit did not equate to better outcomes nor a reduc-
tion in dislocation rates and other complications. Techni-
cal unreliability with active systems was a significant issue,
resulting in manual conversion in up to 18% of cases.23
Newer semi-active systems such as Mako allow for greater
operating guidance whilst still maintaining the benefits
of robotic precision for both acetabular reaming and cup
placement. Further benefits include intra-operative calcu-
lations of hip length, offset and combined version, and
the ability to make the relevant component adjustments
accordingly. This semi-active system therefore shows a
higher degree of accuracy in terms of component posi-
tioning compared to previous active systems.
The higher complication rates in certain comparative
studies with fully active systems compared to manual
THA highlights the risks of using robotic technology
which could potentially overshadow their benefits.23,28
The semi-active system Mako has demonstrated more
favourable outcomes, however, with similar overall com-
plication rates compared to manual THA.62 Specific com-
plications such as blood loss and dislocation rates appear
reduced in robotic THA using this semi-active system but
increased in previous fully active systems. In terms of dis-
location rates this may be due to the dependency of these
871
Robotics in total hip aRthRoplasty
preceding active systems on manual acetabular prepara-
tion and implantation.3,28 Potential soft tissue damage
with certain active systems may have also been a contrib-
uting factor.28
Although robotic innovation is an exciting develop-
ment in hip arthroplasty, it has yet to demonstrate superior
functional outcome scores or improved patient satisfaction
compared to conventional THA. This lack of difference is
perhaps a testament to the already great success of the
latter. Any potential improvement in functional outcome
is likely to be narrow, and therefore measured outcome
scores used should enable ‘good’ and ‘excellent’ differ-
ences to be clearly defined.20 Unfortunately, the majority
of robotic studies so far have utilized outcome scores such
as the HHS and Merle d’Aubigné–Postel score which are
limited in this regard by their high ceiling effects.20,73,74
This may contribute to previous robotic studies showing
little difference in functional scores compared to manual
THA. Of note, one study demonstrated poorer scores and
abductor function in the robotic group although this active
system is no longer in use.28 Recent functional outcome
data for Mako, however, are encouraging, although long-
term follow up is required.3,65
One potential issue with closed systems like Mako is
the limited variation of compatible prostheses. Surgeons
wishing to embrace this technology may therefore have
to change their preferred implant choice. As a result,
a learning curve relating to new implant usage may be
introduced, independent of robotic technology. One argu-
ment, however, is that reduction in variation may reduce
overall implant costs, which could potentially offset some
of the upfront costs of robotic technology. A recent study
by Boylan et al noted that adoption of a single preferred
vendor for hip and knee arthroplasty reduced costs by
23% per case in the first year.75 Despite the potential
learning curve with new unfamiliar implants, there was
no difference in short-term quality metrics in this study,
although higher-volume surgeons were more reluctant to
change implant.
Most robots currently used in THA are closed systems.
This not only limits the comparison of individual robotic
systems with manual implantation of different implants,
but also prevents, in most cases, the evaluation of different
robotic systems utilizing the same implant. Any long-term
comparisons between such technologies should take into
account that differences in outcome measures and survi-
vorship may be due to individual prosthesis design as well
as the additional accuracy that robots provide. Whether
one of these factors has a greater impact in the long term
may be difficult to establish even with registry data.
Although previous active systems appear redundant, in
the future there may be a resurgence of interest with the
TSolution One system. This fully active system is based on
the legacy of the ROBODOC, but unlike its predecessor
allows preparation and component implantation of the
acetabulum in addition to femoral preparation. This
theoretical improved accuracy in combined component
version may potentially address previous concerns of
increased dislocation compared to manual techniques
in previous active systems.23 Outcome studies, however,
have yet to be published.
Conclusion
Although robotic-assisted THA is associated with lower
complication rates and superior radiographic outcomes
compared to conventional THA, short- and long-term
functional outcomes remain equivocal.63,64 It must be
noted that this evidence is based upon limited data from a
handful of studies, the majority of which are based on pre-
vious robotic systems that are now redundant. The results
of the newer semi-active system, Mako, are promising,
with greater accuracy of implant positioning relating to
the safe zones, restoration of hip offset, and native cen-
tre of rotation.49,62 Further work is necessary to establish
whether these improvements lead to a significant reduc-
tion in complications and improved long-term outcomes.
The variation in technical failures, surgical complications
and outcome measures between systems highlights
the importance of appraising the merits of each system
individually to fully quantify the true benefits and risks of
robotic THA.
ICMJE CONFLICT OF INTEREST STATEMENT
The authors declare no conict of interest relevant to this work.
FUNDING STATEMENT
No benets in any form have been received or will be received from a commercial
party related directly or indirectly to the subject of this article.
LICENCE
© 2020 The author(s)
This article is distributed under the terms of the Creative Commons Attribution-Non
Commercial 4.0 International (CC BY-NC 4.0) licence (https://creativecommons.org/
licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribu-
tion of the work without further permission provided the original work is attributed.
AUTHOR INFORMATION
1Department of Trauma and Orthopaedics, King’s College Hospital, London, UK.
2Oxford Trauma, Nuffield Department of Orthopaedics, Rheumatology and
Musculoskeletal Sciences, University of Oxford, Oxford, UK.
3Department of Trauma and Orthopaedics, Guy’s and St Thomas’ NHS Foundation
Trust, London, UK.
Correspondence should be sent to: Jean-Pierre St Mart, Department of Trauma
and Orthopaedics, King’s College Hospital, Denmark Hill, London, SE5 9RS, UK.
Email: jstmart@nhs.net
872
REFERENCES
. Ali Khan MA, Brakenbury PH, Reynolds ISR. Dislocation following total hip
replacement. J Bone Joint Surg Br 1981;63:214–218.
. Biedermann R, Tonin A, Krismer M, Eibl G, Stöckl B. Reducing the risk of
dislocation after total hip arthroplasty. J Bone Jt Surg - Ser B 2005;87:762–769.
. Bukowski BR, Anderson P, Khlopas A, Chughtai M, Mont MA, Illgen RL II.
Improved functional outcomes with robotic compared with manual total hip arthroplasty.
Surg Technol Int 2016;29:303–308.
. Kennedy JG, Rogers WB, Soe KE, Sullivan RJ, Grien DG, Sheehan
LJ. Effect of acetabular component orientation on recurrent dislocation, pelvic osteolysis,
polyethylene wear, and component migration. J Arthroplasty 1998;13:530–534.
. Leslie IJ, Williams S, Isaac G, Ingham E, Fisher J. High cup angle and
microseparation increase the wear of hip surface replacements. Clin Orthop Relat Res
2009;467:2259–2265.
. Morrey BF. Difficult complications after hip joint replacement: dislocation. Clin Orthop
Relat Res Ovid Technologies 1997;344:179–187.
. Won YS, Baldini T, Peterson MG, Wright TM, Salvati EA. Impingement in total
hip arthroplasty: a study of retrieved acetabular components. J Arthroplasty 2005;20:427–435.
. Widmer KH, Zuruh B. Compliant positioning of total hip components for optimal
range of motion. J Orthop Res 2004;22:815–821.
. Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations
after total hip-replacement arthroplasties. J Bone Jt Surg - Ser A 1978;60A:217–220.
. Little NJ, Busch CA, Gallagher JA, Rorabeck CH, Bourne RB. Acetabular
polyethylene wear and acetabular inclination and femoral offset. Clin Orthop Relat
2009;467:2895–2900.
. Asayama I, Chamnongkich S, Simpson KJ, Kinsey TL, Mahoney OM.
Reconstructed hip joint position and abductor muscle strength after total hip arthroplasty.
J Arthroplasty 2005;20:414–420.
. Kurtz WB, Ecker TM, Reichmann WM, Murphy SB. Factors affecting bony
impingement in hip arthroplasty. J Arthroplasty 2010;25:624–634.e2.
. Parvizi J, Kim K-I, Goldberg G, Mallo G, Hozack WJ. Recurrent instability after
total hip arthroplasty: beware of subtle component malpositioning. Clin Orthop Relat Res
2006;447:60–65.
. Cassidy KA, Noticewala MS, Macaulay W, Lee JH, Geller JA. Effect of femoral
offset on pain and function after total hip arthroplasty. J Arthroplasty 2012;27:1863–1869.
. Kayani B, Konan S, Ayuob A, Ayyad S, Haddad FS. The current role of robotics
in total hip arthroplasty. EFORT Open Rev 2019;4:618–625.
. Karunaratne S, Duan M, Pappas E, et al. The effectiveness of robotic hip and
knee arthroplasty on patient-reported outcomes: a systematic review and meta-analysis. Int
Orthop 2019;43:1283–1295.
. Davies B. A review of robotics in surgery. Proc Inst Mech Eng Part H J Eng Med
2000;214:129–140.
. Facca S, Hendriks S, Mantovani G, Selber JC, Liverneaux P. Robot-assisted
surgery of the shoulder girdle and brachial plexus. Semin Plast Surg 2014;28:39–44.
. Subramanian P, Wainwright TW, Bahadori S, Middleton RG. A review of
the evolution of robotic-assisted total hip arthroplasty. HIP Int 2019;29:232–238.
. Perets I, Mu BH, Mont MA, Rivkin G, Kandel L, Domb BG. Current topics in
robotic-assisted total hip arthroplasty: a review. HIP Int 2020;30:118–124.
. Bargar WL, Bauer A, Börner M. Primary and revision total hip replacement using
the ROBODOC® system. Clin Orthop Relat Res 1998;354:82–91.
. Bargar WL, Parise CA, Hankins A, Marlen NA, Campanelli V, Netravali
NA. Fourteen year follow-up of randomized clinical trials of active robotic-assisted total hip
arthroplasty. J Arthroplasty. 2018;33:810–814.
. Honl M, Dierk O, Gauck C, et al. Comparison of robotic-assisted and manual
implantation of a primary total hip replacement: a prospective study. J Bone Joint Surg Am
2003;85:1470–1478.
. Nogler M, Maurer H, Wimmer C, Gegenhuber C, Bach C, Krismer M. Knee
pain caused by a fiducial marker in the medial femoral condyle: a clinical and anatomic study
of 20 cases. Acta Orthop Scand 2001;72:477–480.
. Schulz AP, Seide K, Queitsch C, Haugwitz A Von, Meiners J, Kienast B,
et al. Results of total hip replacement using the Robodoc surgical assistant system: clinical
outcome and evaluation of complications for 97 procedures. Int J Med Robot Comput Assist
Surg 2007;3:301–306.
. Decking J, Gerber A, Kränzlein J, Meurer A, Böhm B, Plitz W. The primary
stability between manual and robot assisted implantation of hip prostheses: a biomechanical
study on synthetic femurs. Z Orthop Ihre Grenzgeb 2004;142:309–313.
. Prymka M, Wu L, Hahne HJ, Koebke J, Hassenpug J. The dimensional
accuracy for preparation of the femoral cavity in HIP arthroplasty. Arch Orthop Trauma Surg
2006;126:36–44.
. Siebel T, Käfer W. Klinisches outcome nach roboter-assistierter versus
konventionell implantierter hüftendoprothetik: Prospektive, kontrollierte untersuchung von
71 patienten. Z Orthop Ihre Grenzgeb 2005;143:391–398.
. Mazoochian F, Pellengahr C, Huber A, Kircher J, Reor HJ, Jansson
V. Low accuracy of stem implantation in THR using the CASPAR-system: anteversion
measurements in 10 hips. Acta Orthop Scand 2004;75:261–264.
. Jacofsky DJ, Allen M. Robotics in arthroplasty: a comprehensive review.
J Arthroplasty 2016;31:2353–2363.
. Allen MW, Jacofsky DJ. Evolution of robotics in arthroplasty. In: Lonner JH,
ed. Robotics in knee and hip arthroplasty. Cham: Springer International Publishing,
2019:13–25.
. Barrett ARW, Davies BL, Gomes MPSF, Harris SJ, Henckel J, Jakopec M,
et al. Computer-assisted hip resurfacing surgery using the Acrobot® Navigation System.
Proc Inst Mech Eng Part H J Eng Med 2007;221:773–785.
. Sousa PL, Sculco PK, Mayman DJ, Jerabek SA, Ast MP, Chalmers BP.
Robots in the operating room during hip and knee arthroplasty. Curr Rev Musculoskelet Med
2020;13:309–317.
. St Mart J-PB, Donnelly WJ, Crawford RW. Robotically assisted total hip
arthroplasty. In: Timperley AJ, ed. The Exeter Hip: 50 years of innovation in total hip
arthroplasty. Second ed. United Kingdom: Exeter Hip Publishing, 2020:171–182.
. Ranawat CS. Techniques of cemented total hip arthroplasty. Tech Orthop
1991;6:17–25.
. Dorr LD, Malik A, Dastane M, Wan Z. Combined anteversion technique for total
hip arthroplasty. Clin Orthop Relat Res 2009;467:119–127.
. Wasterlain AS, Buza JA, Thakkar SC, Schwarzkopf R, Vigdorchik
J. Navigation and robotics in total hip arthroplasty. JBJS Rev 2017 Mar 14;5:01874474-
201703000-00005.
. Banerjee S, Cherian JJ, Elmallah RK, Pierce TP, Jauregui JJ, Mont MA.
Robot-assisted total hip arthroplasty. Expert Rev Med Devices 2016;13:47-56.
. Lang JE, Mannava S, Floyd AJ, et al. Robotic systems in orthopaedic surgery.
J Bone Jt Surg - Ser B 2011;93B:1296–1299.
873
Robotics in total hip aRthRoplasty
. Ranawat CS, Maynard MJ. Modern technique of cemented total hip arthroplasty.
Tech Orthop 1991;6:17–25.
. Nakamura N, Sugano N, Nishii T, Kakimoto A, Miki H. A comparison
between robotic-assisted and manual implantation of cementless total hip arthroplasty. Clin
Orthop Relat Res 2010;468:1072–1081.
. Nishihara S, Sugano N, Nishii T, Miki H, Nakamura N, Yoshikawa H.
Comparison between hand rasping and robotic milling for stem implantation in cementless
total hip arthroplasty. J Arthroplasty 2006;21:957–966.
. Wu L-d, Hahne HJ, Hassenpflug J. The dimensional accuracy of
preparation of femoral cavity in cementless total hip arthroplasty. J Zhejiang Univ Sci
2004;5:1270–1278.
. Schneider J, Kalender W. Geometric accuracy in robot-assisted total hip
replacement surgery. Comput Aided Surg 2003;8:135–145.
. Stiehl JB, Konermann WH, Haaker RG, Thomsen M. Robotically milled bone
cavities in comparison with hand-broaching in total hip replacement. Berlin Heidelberg:
Springer, 2004:123–131.
. Prymka M, Vogiatzis M, Hassenpug J. Primäre rotationsstabilität von
roboterunterstützt und manuell implantierbaren hüftendoprothesenschäften. Z Orthop Ihre
Grenzgeb 2004;142:303–308.
. Domb BG, Chandrasekaran S, Gui C, Yuen LC, Lodhia P, Suarez C. Can
stem version consistently correct native femoral version using robotic guidance in total hip
arthroplasty? Surg Technol Int 2017:389–395.
. Callanan MC, Jarrett B, Bragdon CR, et al. The John Charnley award: risk
factors for cup malpositioning: quality improvement through a joint registry at a tertiary
hospital. Clin Orthop Relat Res 2011;469:319–329.
. Illgen RL, Bukowski BR, Abiola R, et al. Robotic-assisted total hip arthroplasty:
outcomes at minimum two-year follow-up. Surg Technol Int 2017;30:365–372.
. Domb BG, Bitar YF El, Sadik AY, Stake CE, Botser IB. Comparison of robotic-
assisted and conventional acetabular cup placement in THA: a matched-pair controlled
study hip. Clin Orthop Relat Res 2014;472:329–336.
. Kamara E, Robinson J, Bas MA, Rodriguez JA, Hepinstall MS. Adoption of
robotic vs fluoroscopic guidance in total hip arthroplasty: is acetabular positioning improved
in the learning curve? J Arthroplasty 2017;32:125–130.
. Kong X, Yang M, Jerabek S, Zhang G, Chen J, Chai W. A retrospective
study comparing a single surgeon’s experience on manual versus robot-assisted total
hip arthroplasty after the learning curve of the latter procedure: a cohort study. Int J Surg
2020;77:174–180.
. Choi YW, Kim S-G. The short-term clinical outcome of total hip arthroplasty using
short metaphyseal loading femoral stem. Hip Pelvis 2016;28:82–89.
. Loppini M, Grappiolo G. Uncemented short stems in primary total hip arthroplasty:
the state of the art. EFORT Open Rev 2018;3:149–159.
. Lim SJ, Kim SM, Lim BH, Moon YW, Park YS. Comparison of manual rasping
and robotic milling for short metaphyseal-fitting stem implantation in total hip arthroplasty:
a cadaveric study. Comput Aided Surg 2013;18:33–40.
. Lim SJ, Ko KR, Park CW, Moon YW, Park YS. Robot-assisted primary cementless
total hip arthroplasty with a short femoral stem: a prospective randomized short-term
outcome study. Comput Aided Surg 2015;20:41–46.
. Alexander JW, Kamaric E, Noble PC. The accuracy of acetabular reaming in
total hip replacement. Ace 1999. https://www.ors.org/Transactions/45/0906.PDF (date last
accessed 2 November 2020).
. Suarez-Ahedo C, Gui C, Martin TJ, Chandrasekaran S, Lodhia P, Domb
BG. Robotic-arm assisted total hip arthroplasty results in smaller acetabular cup size in
relation to the femoral head size: a matched-pair controlled study. HIP Int 2017;27:147–152.
. Ranawat CS. The pants too short, the leg too long! Orthopedics 1999;22:845–846.
. Hofmann AA, Skrzynski MC. Leg-length inequality and nerve palsy in total hip
arthroplasty: a lawyer awaits! Orthopedics 2000;23:943–944.
. Nawabi DH, Conditt MA, Ranawat AS, Dunbar NJ, Jones J, Banks S, et al.
Haptically guided robotic technology in total hip arthroplasty: a cadaveric investigation. Proc
Inst Mech Eng Part H J Eng Med 2013;227:302–309.
. Kayani B, Konan S, Thakrar RR, Huq SS, Haddad FS. Assuring the long-term
total joint arthroplasty: a triad of variables. Bone Jt J 2019;101B:11–18.
. Chen X, Xiong J, Wang P, Zhu S, Qi W, Peng H, et al. Robotic-assisted
compared with conventional total hip arthroplasty: systematic review and meta-analysis.
Postgrad Med J 2018;94:335–341.
. Han P-F, Chen C-L, Zhang Z-L, et al. Robotics-assisted versus conventional
manual approaches for total hip arthroplasty: a systematic review and meta-analysis of
comparative studies. Int J Med Robot Comput Assist Surg 2019;15:e1990–e1990.
. Perets I, Walsh JP, Close MR, Mu BH, Yuen LC, Domb BG. Robot-assisted
total hip arthroplasty: clinical outcomes and complication rate. Int J Med Robot Comput Assist
Surg 2018;14:e1912.
. de Steiger RN, Lorimer M, Solomon M. What is the learning curve for the
anterior approach for total hip arthroplasty? Clin Orthop Relat Res 2015;473:3860–3866.
. Redmond JM, Gupta A, Hammarstedt JE, Petrakos AE, Finch NA, Domb
BG. The learning curve associated with robotic-assisted total hip arthroplasty. J Arthroplasty
2015;30:50–54.
. Kayani B, Konan S, Huq SS, Ibrahim MS, Ayuob A, Haddad FS. The learning
curve of robotic-arm assisted acetabular cup positioning during total hip arthroplasty. HIP Int
2019;112070001988933 [Epub ahead of print].
. Bargar WL. Robots in orthopaedic surgery: past, present, and future. Clin Orthop
Relat Res 2007;463:31–36.
. Chen KK, Kim KY, Vigdorchik JM, Meere PA, Bosco JA, Iorio R. Cost-
effectiveness analysis of robotic arthroplasty. In: Lonner JH, ed. Robotics in knee and hip
arthroplasty. Switzerland: Springer International Publishing, 2019:67–74.
. Frost & Sullivan. Comprehensive Care for Joint Replacement (CJR) ROI model –
comparative analysis of robot assisted versus conventional surgical technique, 2017. https://
ww2.frost.com/news/press-releases/new-frost-sullivan-white-paper-shows-how-
thousands-more-americans-can-access-benefits-robotic-assisted-knee-replacement/
(date last accessed 2 November 2020).
. Robinson JC, Pozen A, Tseng S, Bozic KJ. Variability in costs associated with
total hip and knee replacement implants. J Bone Joint Surg Am 2012;94:1693–1698.
. Øvre S, Sandvik L, Madsen JE, Røise O. Comparison of distribution, agreement
and correlation between the original and modified Merle d’Aubigné-Postel Score and the
Harris Hip Score after acetabular fracture treatment: moderate agreement, high ceiling effect
and excellent correlation in 450 patients. Acta Orthop 2005;76:796–802.
. Wamper KE, Sierevelt IN, Poolman RW, Bhandari M, Haverkamp D.
The Harris Hip Score: do ceiling effects limit its usefulness in orthopedics? Acta Orthop
2010;81:703–707.
. Boylan MR, Chadda A, Slover JD, Zuckerman JD, Iorio R, Bosco JA.
Preferred single-vendor program for total joint arthroplasty implants: surgeon adoption,
outcomes, and cost savings. J Bone Joint Surg Am 2019;101:1381–1387.
