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Computerised tomography-based planning with conventional total hip arthroplasty versus robotic-arm assisted total hip arthroplasty: Study protocol for a prospective randomised controlled trial

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Background: Robotic-arm assisted surgery aims to reduce manual errors and improve the accuracy of implant positioning during total hip arthroplasty. The objective of this study is to compare the accuracy of implant positioning, restoration of hip biomechanics, patient satisfaction, functional outcomes, implant survivorship, cost-effectiveness, and complications in conventional manual total hip arthroplasty (CO THA) versus robotic-arm assisted total hip arthroplasty (RO THA). Preoperative pelvic computerised tomography (CT) scans will be used to create patient-specific, virtual, three-dimensional reconstructions for surgical planning in both treatment groups. Methods and analysis: This prospective randomised controlled trial will include 60 patients with symptomatic hip osteoarthritis undergoing primary THA. Following informed consent, patients will be randomised to CO THA (control group) or RO THA (investigation group) at a ratio of 1:1 using an online random number generator. Observers will review patients at regular intervals for 2 years after surgery to record predefined study outcomes relating to the accuracy of implant positioning, hip biomechanics, postoperative rehabilitation, clinical progress, functional outcomes, cost-effectiveness, and complications. Primary and secondary objectives will be used to quantify and draw inferences on differences in the efficacy of treatment between the two groups. Intention-to-treat and per-protocol population analysis will be undertaken. Intention to treat relates to the allocated treatment (CO THA or RO THA), and per-protocol refers to the actual treatment received by the patient. The following statistical methods will be employed to analyse the data: descriptive statistics, independent t test, paired t test, analysis of variance, Fisher exact test, chi-square test, and graphical displays. Ethical approval was obtained from the London-Bromley Research Ethics Committee, UK. The study is sponsored by University College London, UK. Discussion: This study compares a comprehensive and robust range of clinical, functional, and radiological outcomes in CT-planned CO THA versus CT-planned RO THA. The findings of this study will enable an improved understanding of the differences in CO THA versus RO THA with respect to patient satisfaction, functional outcomes, implant survivorship, cost-effectiveness, and complications. Trial registration: ClinicalTrials.gov NCT04095845 . Registered on 19 September 2019.
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S T U D Y P R O T O C O L Open Access
Computerised tomography-based planning
with conventional total hip arthroplasty
versus robotic-arm assisted total hip
arthroplasty: study protocol for a
prospective randomised controlled trial
Babar Kayani
*
, Sujith Konan, Jenni Tahmassebi, Atif Ayuob and Fares S. Haddad
Abstract
Background: Robotic-arm assisted surgery aims to reduce manual errors and improve the accuracy of implant
positioning during total hip arthroplasty. The objective of this study is to compare the accuracy of implant
positioning, restoration of hip biomechanics, patient satisfaction, functional outcomes, implant survivorship, cost-
effectiveness, and complications in conventional manual total hip arthroplasty (CO THA) versus robotic-arm assisted
total hip arthroplasty (RO THA). Preoperative pelvic computerised tomography (CT) scans will be used to create
patient-specific, virtual, three-dimensional reconstructions for surgical planning in both treatment groups.
Methods and analysis: This prospective randomised controlled trial will include 60 patients with symptomatic hip
osteoarthritis undergoing primary THA. Following informed consent, patients will be randomised to CO THA
(control group) or RO THA (investigation group) at a ratio of 1:1 using an online random number generator.
Observers will review patients at regular intervals for 2 years after surgery to record predefined study outcomes
relating to the accuracy of implant positioning, hip biomechanics, postoperative rehabilitation, clinical progress,
functional outcomes, cost-effectiveness, and complications. Primary and secondary objectives will be used to
quantify and draw inferences on differences in the efficacy of treatment between the two groups. Intention-to-treat
and per-protocol population analysis will be undertaken. Intention to treat relates to the allocated treatment (CO
THA or RO THA), and per-protocol refers to the actual treatment received by the patient. The following statistical
methods will be employed to analyse the data: descriptive statistics, independent ttest, paired ttest, analysis of
variance, Fisher exact test, chi-square test, and graphical displays. Ethical approval was obtained from the London-
Bromley Research Ethics Committee, UK. The study is sponsored by University College London, UK.
Discussion: This study compares a comprehensive and robust range of clinical, functional, and radiological
outcomes in CT-planned CO THA versus CT-planned RO THA. The findings of this study will enable an improved
understanding of the differences in CO THA versus RO THA with respect to patient satisfaction, functional
outcomes, implant survivorship, cost-effectiveness, and complications.
Trial registration: ClinicalTrials.gov NCT04095845. Registered on 19 September 2019
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* Correspondence: babar.kayani@gmail.com
Department of Trauma and Orthopaedic Surgery, University College Hospital,
235 Euston Road, Fitzrovia, London NW1 2BU, UK
Kayani et al. Trials (2020) 21:776
https://doi.org/10.1186/s13063-020-04702-7
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Background
Total hip arthroplasty (THA) is a highly successful surgi-
cal treatment for symptomatic hip osteoarthritis, which
is performed in over 70,000 patients per year in the UK
[1]. The procedure has well-established middle- to long-
term clinical outcomes, and implant survivorship is
greater than 90% at a minimum of 10 yearsfollow-up
[24]. Achieving accurate implant positioning and restor-
ing native hip biomechanics are important technical ob-
jectives in THA. Studies have shown accuracy and
reproducibility of achieving these surgeon-controlled
factors during THA influences postoperative acetabular
bone stock, abductor function, joint stability, soft tissue
injury, impingement, bearing surface wear, and long-
term implant survival [3,5,6,12,15,18,23]. Conven-
tional manual THA (CO THA) uses radiographic tem-
plating, surgical alignment guides, and intraoperative
landmarks such as the transverse acetabular ligament to
help guide acetabular reaming and implant positioning.
However, it is reported that only 3847% of acetabular
components are within the desired range of anteversion
and inclination with CO THA, and low surgeon volume
is a risk factor for inaccurate implant positioning [2,3,
8,10]. Suboptimal implant positioning outside of the ac-
ceptable safe ranges may lead to increased hip instability,
poor restoration of native hip biomechanics, and prema-
ture component failure requiring more complex revision
surgery [3,10,11,15,16].
Evolution in surgical technology has led to the devel-
opment of robotic-arm assisted THA (RO THA), which
aims to facilitate preoperative surgical planning, reduce
intraoperative errors in bone resection, and improve the
accuracy of implant positioning compared to CO THA.
Preoperative computerised tomography (CT) scans of
the pelvis and proximal femur are used to create virtual
three-dimensional reconstructions of the patients anat-
omy. The surgeon uses this patient-specific computer-
aided design (CAD) model to map optimal implant posi-
tioning to achieve the desired bone coverage, component
positioning, hip biomechanics, and correction of any
limb-length discrepancy. An intraoperative robotic de-
vice with audio, visual, and tactile feedback helps to exe-
cute the planned bone resection and implant positioning
plan with a high level of accuracy. Existing reports com-
paring CO THA versus RO THA have shown conflicting
outcomes [6,14,15,20,22]. Initial studies found RO
THA was associated with improved functional outcomes
as assessed using the Harris ship score, increased accur-
acy of acetabular implant positioning, better preservation
of acetabular bone stock, improved restoration of native
femoral offset, and reduced postoperative leg-length in-
equality compared to CO THA [6,7,9,14,15,20].
However, further studies have shown no difference in
CO THA versus RO THA with respect to functional
outcomes, implant survivorship, and complications at
short-term follow-up [4,17,19,21]. Delays in the wide-
spread implementation of RO THA have been attributed
to the limited data showing any functional benefit with
this procedure compared to an already established and
highly cost-effective CO THA [7,13].
Illgen et al. reviewed outcomes in 200 consecutive CO
THAs followed by 100 consecutive RO THAs and found
RO THA was associated with an additional 71% im-
provement in the accuracy of acetabular implant posi-
tioning compared with manual THA in the first year of
use [9]. Acetabular implant positioning within Lewin-
neks safe zones (inclination, 3050°; anteversion, 525°)
was achieved in 30% of the first 100 consecutive CO
THAs, 45% of the last 100 consecutive CO THAs, and
77% in the first 100 consecutive RO THAs (p< 0.001)
[9]. Domb et al. conducted a retrospective radiological
review of 50 patients undergoing CO THA versus 50 pa-
tients receiving RO THA [6]. All operative procedures
were performed through the posterior approach. The
study showed that all 50/50 (100%) RO THAs had ace-
tabular cup positioning within Lewinneks safe zone
compared to only 40/50 (80%) in the CO THA group
(p= 0.001). Furthermore, 46/50 (92%) RO THAs had ac-
etabular cup positioning within Callanans modified safe
zone (inclination, 3045°; anteversion, 525°) compared
to only 31/50 (62%) in the CO THA group (p= 0.001).
The odds ratio for an implanted acetabular cup out of
Lewinneks safe zones was zero and Callanan et al. was
0.142 (95% CI 0.0440.457). Nawabi et al. conducted a
study on 12 cadaveric specimens that received CO THA
on one side and RO THA on the contralateral side [20].
All procedures were performed using the posterior ap-
proach. The root-mean-square error for manual im-
plantation was five times greater for acetabular cup
inclination and 3.4 times greater for acetabular cup ante-
version compared to robotic-arm assistance (p< 0.01).
Tsai et al. conducted a retrospective study in which 12
patients undergoing RO THAs and 14 patients undergo-
ing CO THAs had postoperative CT scans to assess im-
plant positioning [25]. This study found that there was
increased combined anteversion of 19.1 ± 11.7° in the
RO THA group compared to 23.5 ± 23.6° in the CO
THA group (p< 0.001). Cup inclination decreased by
16.5 ± 6.0° in the robotic THA group compared to
10.2 ± 6.8° in the CO THA group (p< 0.001).
The main limitations of existing studies comparing
CO THA versus RO THA are that they are based on ca-
daveric specimens or retrospective clinical trials with
limited data on functional outcomes, radiological results,
or complications [6,7,9,14,15,20]. Within each treat-
ment group, different preoperative imaging modalities
were used for surgical planning, operative procedures
were performed with varying implant designs, and
Kayani et al. Trials (2020) 21:776 Page 2 of 10
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postoperative rehabilitation was not standardised. Ob-
servers recording outcomes were not blinded to the
treatment group, and follow-up of outcomes and com-
plications within each treatment group was limited to
the early postoperative period [6,7,9,14,15,20]. There
is a need for high-quality evidence comparing CO THA
versus RO THA. It is possible to improve on these previ-
ous studies by using the same preoperative planning
technique in both treatment groups, prospectively ran-
domising study patients to the treatment groups, and
collecting data on a more comprehensive and robust
range of clinical, functional, and radiological outcomes.
All operative procedures will be undertaken using the
standard posterior approach, sitting and standing spino-
pelvic radiographs will be used to assess patient-specific
functional pelvic kinematics, and identical implant de-
signs will be used in both treatment groups, which will
help to blind observers recording radiological outcomes.
The findings of this study will enable an improved un-
derstanding of differences in CO THA versus RO THA
with respect to patient satisfaction, functional outcomes,
implant survivorship, cost-effectiveness, and
complications.
Methods/design
Objectives
The primary objective of this study is to compare the ac-
curacy of achieving the planned centre of hip rotation in
CO THA versus RO THA. This will be assessed within
each treatment group by measuring the difference in the
achieved centre of rotation on postoperative CT scano-
gram compared to the planned centre of rotation on
preoperative pelvic CT scan. The study hypothesis is
that RO THA will improve the accuracy of achieving the
planned centre of rotation compared to CO THA.
The secondary objectives are to compare the following
outcomes between the two treatment groups:
1. Accuracy of achieving planned component
positioning
2. Accuracy of restoring planned hip biomechanics
3. Spinopelvic functional kinematics
4. Surgical efficiency
5. Postoperative functional rehabilitation
6. Functional outcomes
7. Quality of life
8. Range of motion
9. Resource use and cost-effectiveness
10. Complications
Specific study outcomes related to the primary and
secondary objectives are discussed in the Outcomes
section below.
Trial design
This study is a prospective, single-centre, randomised
controlled trial. The study will be undertaken in the De-
partment of Trauma and Orthopaedics, University Col-
lege Hospital, 235 Euston Road, Bloomsbury, London
NW1 2BU, UK. The study will include 60 patients ran-
domly allocated to either CO THA (control group) or
RO THA (investigation group). The study commenced
patient recruitment in December 2018 and is expected
to complete patient recruitment in December 2020. All
patients will be followed up for 2 years after surgery, and
therefore, the anticipated completion date for the study
is December 2022. The study is sponsored by University
College London, UK. The patient enrolment flow chart
is presented in Fig. 1. The schedule of enrolment, inter-
ventions, and assessments for all study patients is shown
in Fig. 2.
Eligibility criteria
The inclusion criteria for this study are as follows: pa-
tient has symptomatic hip osteoarthritis requiring pri-
mary THA, patient fit for surgical intervention following
review by surgeon and anaesthetist, patient aged be-
tween 18 and 80 years at time of surgery, patient able to
give informed consent and agrees to comply with the
postoperative review programme, and patient has suffi-
cient mobility to attend follow-up clinics. The exclusion
criteria for this study are as follows: patient undergoing
revision surgery or second-stage THA, patients in whom
the planned hip biomechanics are in a different position
to the contralateral hip (e.g. developmental dysplasia of
the hip or protrusio acetabuli), patient not suitable to
have the planned study implants (e.g. requiring dual mo-
bility component or cemented implants), patient had
previous contralateral THA, patient is immobile or has
another neurological condition affecting musculoskeletal
function, patient already enrolled on another concurrent
clinical trial, patient unable or unwilling to sign the in-
formed consent form specific to this study, and patient
unable to attend the study follow-up programme.
Recruitment
Patients will be recruited from the orthopaedic out-
patient clinic at University College Hospital, London,
UK. All patients will be screened by the clinical team
(orthopaedic consultant surgeon, clinical research fellow,
and orthopaedic registrar) for study participation based
on the predefined inclusion and exclusion criteria listed
above. Patients that fulfil the eligibility criteria and ex-
press an interest to participate in the study will be pro-
vided with an ethics committee-approved patient
information sheet. This provides details about the study
treatment, follow-up, and contact details for further in-
formation. All members of the clinical team are familiar
Kayani et al. Trials (2020) 21:776 Page 3 of 10
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with the study and will address any preliminary ques-
tions about the study. Details of those patients express-
ing an interest to participate in the study will be
recorded in the patient contact form and forwarded to
the research physiotherapist. The research physiotherap-
ist will phone the patient 4 weeks after this consultation
to discuss any further questions and confirm if the pa-
tient would like to participate in the study.
Consent
Informed consent will be obtained by the chief investiga-
tor or principal investigator when the patient attends for
the preoperative planning CT scan. This is 6 weeks after
the outpatient consultation for agreement to THA and
2 weeks before surgery. It is important to the data col-
lection scheme that patients are able to follow com-
mands, read, and interpret questions via questionnaires.
For those who cannot hear, read, or understand English,
an interpreter will be provided. The consent form de-
scribes the benefits and complications associated with
THA and details additional risks associated with partici-
pation in this study, including additional radiation ex-
posure (equivalent to two plain radiographs) compared
to routine (non-research) patients undergoing THA. The
consent form also explains that patients are free to with-
draw from the study at any timepoint without their
medical or legal rights being affected, their medical notes
will be reviewed by the research team, and their general
practitioners will be informed of their participation in
the study.
Allocation
After informed consent has been obtained, the research
physiotherapist will randomise the patient into one of
the two treatment groups using an online random num-
ber generator (www.random.org). A number from 1 to
Fig. 1 Patient enrolment flow chart
Kayani et al. Trials (2020) 21:776 Page 4 of 10
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60 can be randomly generated and will allocate a patient
to one of the two arms of the study: 130 inclusive for
the control group, 3160 inclusive for the investigation
group. The research physiotherapist will perform the
randomisation procedure and store the designated treat-
ment group for each patient on a password-encrypted
file on the hospital computer. The operating surgeon
will have this information communicated to him on the
morning of surgery.
Preoperative imaging
All patients will undergo preoperative imaging with sit-
ting and standing spinopelvic radiographs, pelvic and hip
radiographs, and CT scan of the pelvis and proximal
femur. Preoperative templating will be undertaken by
the operating surgeon. In both treatment groups, pelvic
radiographs will be exported onto Traumacad software
(Traumacad, Petach-Tikva, Israel) to template implant
positioning and sizes for achieving the planned bone
coverage, horizontal and vertical centres of rotation, ace-
tabular and femoral offset, and leg-length correction. In
all patients, the pelvic CT scan will be uploaded onto a
computer software programme (Mako Surgical, Kalama-
zoo, MI, USA) to create a patient-specific CAD model of
the patients osseous anatomy. The operating surgeon
will use this virtual three-dimensional reconstruction to
plan the operative procedure to restore the patients na-
tive hip biomechanics as guided by the contralateral side.
In both treatment groups, the surgical objectives will be
to restore the native horizontal and vertical centres of
rotation, reproduce the native combined offset, restore
natural femoral and acetabular version and inclination
within Lewinneks and Callanans safe zones, and fully
correct any pre-existing leg-length discrepancy. The
computer robotic software will be used to calculate the
required acetabular bone reaming, femoral osteotomy
site, implant size, and implant positioning for achieving
these surgical objectives.
Surgical intervention
In patients undergoing CO THA, the femoral osteotomy
site will be marked using the patient-specific CAD using
Legend: CO THA – Conventional manual total hip arthroplasty; RO THA – Robotic-arm assisted total hip
arthro
p
last
y
; CT- Com
p
uterised tomo
g
ra
p
h
y
STUDY PERIOD
Enrolment Pre-op CT Allocation Post-allocation Close-
out
TIMEPOINT -8 weeks -2 weeks 0 2 weeks 6 weeks 6 months 1 year 2 year
ENROLMENT:
Eligibility screen X
Informed consent X
Allocation X
INTERVENTIONS:
CO THA X
RO THA X
ASSESSMENT S:
Demographics &
Baseline variables
X
Operative outcomes X
Patient-reported
outcome measures
XXXXX
Clinical examination XXXXXX
Adverse events XXXXXXXX
Plain pelvis and hip
radiographs XX XX
Sitting & standing
spinopelvic
radiographs
XX
CT scanogram X
Fig. 2 Schedule of enrolment, interventions, and assessments for all study patients
Kayani et al. Trials (2020) 21:776 Page 5 of 10
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measurements from the greater and lesser trochanters
with the femoral neck cutting guide in place. An oscillat-
ing saw will be used to perform the osteotomy with
Hohmann retractors protecting the surrounding soft tis-
sues. The femoral osteotomy will be performed with the
saw blade 45° to the femoral shaft and in the plane of
the tibia. An entry point will be created in the proximal
femur using a box chisel, with sequential reaming until
contact with the cortical bone is felt, and then progres-
sively larger raspers inserted into the proximal femur
while maintaining the planned femoral version. Rasps
will be used until the point where stability can be
achieved with the definitive components. Sharp Hoh-
mann retractors will be positioned over the anterior wall
to lever the femur anteriorly and under the transverse
acetabular ligament to expose the whole acetabulum for
preparation. Soft tissues overhanging the acetabular cir-
cumference will be excised. Osteophytes will also be ex-
cised with an osteotome and the medial wall visualised.
Sharp, hemispherical reamers will be used to remove the
residual acetabular cartilage and expose the underlying
subchondral bone. Reamers will be sequentially in-
creased in size until the planned depth is reached. An
external alignment guide will be attached to the cutting-
edge reamer handle and acetabular impactor to improve
the accuracy of acetabular cup positioning. The trans-
verse acetabular ligament will be used as a fixed internal
anatomical landmark for accurate positioning of the ace-
tabular component within the safe zones of Lewinnek
et al. and Callanan et al. to optimise stability and reduce
the risk of dislocation. Any residual osteophytes will be
removed at this stage using an osteotome and bone nib-
bler, and the trial prosthesis inserted to ensure satisfac-
tory coverage and stability. Line-to-line technique for
acetabular implantation will be used with implantation
of the acetabular cup that is the same size as the last
reamer used, and this will be augmented with two ace-
tabular screws. The final femoral stem will then be im-
planted, femoral head applied to the taper, and hip
reduced. The adjustment to a shorter or longer head can
be performed at this stage.
In patients undergoing RO THA, three threaded regis-
tration pins will be inserted into the iliac crest for the at-
tachment of the fixed pelvic array. One large screw will
be inserted into the junction of the intertrochanteric
ridge and lesser trochanter for the attachment of the
femoral array, and a femoral checkpoint will be inserted
just anterior to the greater trochanter. Femoral registra-
tion will be undertaken by registering and verifying the
position of patient-specific anatomical landmarks dis-
played on the screen. Intraoperative measurements in
the coronal plane as described by Murray will be dis-
played throughout the procedure. The femoral osteot-
omy will be marked using the probe and the osteotomy
performed using an oscillating saw blade with Hohmann
retractors protecting the surrounding soft tissues. The
femur will be prepared with a box chisel, sequential
reamers inserted, and progressively larger rasps inserted
using the planned femoral version. The final rasp will be
left in position and the femoral version recorded. The
pelvic checkpoint will then be positioned outside the ac-
etabular cavity in the bone just superior to the acetabu-
lar rim. Acetabular registration will be undertaken by
registering and verifying the position of osseous land-
marks displayed on the screen. The acetabular position
and orientation may be fine-tuned based on intraopera-
tive data on femoral version and inclination. The RIO
robotic arm interactive orthopaedic system (Mako Surgi-
cal Corporation, Kalamazoo, USA) will be used to guide
acetabular bone reaming within the confines of the hap-
tic tunnel and implant the acetabular component into its
final position and orientation as defined in the surgical
plan. The final stem will then be implanted, trial head
positioned onto the taper, and hip reduced. The femoral
array will be inserted into the femoral screw, and the
leg-length and offset change shown on the screen. The
adjustment to a shorter or longer head can be performed
at this stage.
All surgical procedures will be performed under the
direct supervision of a single surgeon using the standard
posterior approach. Trial implants will be used to assess
hip stability, offset, soft tissue tension, and leg-length
discrepancy prior to implantation of the permanent ace-
tabular and femoral components in both treatment
groups. Patients in both treatment groups will receive
the standard or high-offset Accolade II femoral stem
(Stryker Ltd., Mahwah, NJ, USA) and the trident acetab-
ular shell (Stryker Ltd., Mahwah, NJ, USA). Patients in
both treatment groups will undergo standardised in-
patient and outpatient rehabilitation programmes. This
will include six outpatient physiotherapy sessions at
two-weekly time intervals. Patients will receive
physiotherapy-supervised closed and open chain exer-
cises to transition through four phases of rehabilitation
with predefined milestones relating to the following:
core strength and stability, lower limb proprioception,
muscle strengthening, hip and knee range of motion,
mobility with and without walking aids; ascending and
descending stairs; and functional activities to return to
pre-disease level of activity. Any deviations from the
standardised proforma will be recorded and presented
with the study findings.
Outcomes
All study patients will undergo review by two observers
(one orthopaedic registrar and one clinical research fel-
low) at 6 weeks, 6 months, 1 year, and 2 years following
surgery. During these follow-up times, predefined
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clinical, functional, and radiological outcomes will be re-
corded by these observers using case report forms
(CRFs). The following outcomes will be recorded in all
study patients:
1. Accuracy of achieving the planned implant
positioning and hip biomechanics (horizontal centre
of rotation, vertical centre of rotation, acetabular
offset, femoral offset, and leg-length discrepancy) as
assessed using CT scanograms performed postoper-
atively at 6 weeks
2. Operating time (minutes)
3. Time to hospital discharge (hours)
4. Analgesia requirements during inpatient admission
and postoperatively at 6 weeks, 6 months, 1 year,
and 2 years
5. Patient-reported outcome measures including
Oxford hip score (OHS), Harris hip score (HSS),
Hip disability and osteoarthritis outcome score
(HOOS), University College Hospital hip (UCH)
score, Western Ontario and Mcmaster Universities
Osteoarthritis Index (WOMAC), and University of
California at Los Angeles hip (UCLA) score
preoperatively and postoperatively at 6 weeks, 6
months, 1 year, and 2 years following surgery
6. Health-related quality of life as measured using
European Quality of Life questionnaire with 5
dimensions for adults (EQ-5D) preoperatively and
postoperatively at 6 weeks, 6 months, 1 year, and 2
years
7. Mobilisation distance (metres) and use of mobility
aids during inpatient admission and postoperatively
at 6 weeks, 6 months, 1 year, and 2 years
8. Range of movement (degrees) in the hip joint in the
supine position as assessed with a goniometer
during inpatient admission and postoperatively at 6
weeks, 6 months, 1 year, and 2 years
9. Resource use and cost-effectiveness including com-
parisons between the two treatment groups relating
to operating time, theatre efficiency, equipment and
sterilisation costs, analgesia requirements, inpatient
rehabilitation, time to discharge, outpatient follow-
up, additional imaging costs, and need for further
surgery
10. Complications
Blinding
It is not possible to blind study patients as RO THA is
associated with an additional incision over the iliac crest
for insertion of the acetabular registration pins. How-
ever, all observers recording radiological outcomes will
remain blinded to the treatment group. Study patients
will be identifiable with a unique study number. Only
the research physiotherapist will have the key to identify
individual patients and their respective treatment arm.
Any documents related to the study will be archived dir-
ectly at the study site by the research physiotherapist
within a locked filing cabinet in a locked research office.
This office has swipe card access with on-site security
and 24-h CCTV surveillance. Patient data will be logged
electronically using each patients unique identification
number with computer software on an encrypted,
password-protected research computer.
Sample size
Prior to commencement of this study, a pilot study was
performed to assess the accuracy of restoring the centre
of rotation using CO THA versus RO THA [15]. Using
data from this study, the mean centre of rotation was set
at 3.7 mm for CO THA and 2.9 mm for RO THA, with
standard deviation of 1.0 mm. Using a two-tailed, two
sample ttest with a power of 80% (1β), significance
level of 5%, and an effect size of 0.8, this study required
52 patients (26 in each treatment arm) to detect the
minimum difference between the two treatment groups.
To account for 10% attrition in the sample size during
follow-up, the total sample size was set at 60 patients.
Statistical analysis
The analysis of the per-protocol population will be con-
sidered the primary analysis. The differences between
the CO THA and RO THA groups will be analysed by
calculating the difference from baseline, per patient, and
a two-sided confidence interval for the difference be-
tween the changes from baseline values will be calcu-
lated. This confidence interval will cover the true
difference in the percentage change from baseline with a
probability of 95%. The following statistical methods will
be employed to analyse the data: descriptive statistics,
independent ttest, paired ttest, analysis of variance,
Fisher exact test, chi-square test, and graphical displays.
Assumptions of normality will be tested with the
DAgostino test. Assumptions of homogeneity of vari-
ance will be tested with Levenes test. If the distribu-
tional assumptions are (severely) violated, non-
parametric techniques, such as Mann-Whitneys test will
be employed. In the event that RO THA is converted to
CO THA intraoperatively, analysis will be performed
using the intention-to-treat population and the treat-
ment actually received by the patients. Intraoperative
conversion from RO THA to CO THA will be docu-
mented and presented and published as part of the
study. All statistical analysis will be undertaken by a
blinded observer. Statistical significance is set at a p
value < 0.05 for all analyses, and all statistical analysis
will be performed using SPSS software version 25 (SPSS
Inc., Chicago, IL, USA).
Kayani et al. Trials (2020) 21:776 Page 7 of 10
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Adverse events
Adverse events are defined as any untoward medical oc-
currence in a patient or study participant, which does
not necessarily have a causal relationship with the pro-
cedure involved. A serious adverse event (SAE) is an ad-
verse event that results in hospitalisation or
prolongation of existing hospitalisation, persistent or sig-
nificant disability or incapacity, life-threatening clinical
sequelae, or death. All SAEs during the protocol treat-
ment will be reported directly to the sponsor using the
SAE web form. The chief investigator will also assess the
SAE for severity, causality, seriousness, and expectedness
using pre-existing criteria provided by the sponsor and
inform the Data Safety Monitoring Board (DSMB)
within 3 days of the initial observation of the event. The
protocol treatment period is defined as the period from
the day that the first study patient is recruited into the
trial to the day that the final study patient has completed
the 2-year follow-up. The chief investigator will also in-
form the London-Bromley Research Ethics Committee
and local Health Research Authority within 3 days of the
SAE taking place. Safety aspects of the study are closely
monitored by the sponsor and DSMB using unblinded
data for its judgement. In cases where the SAE arises
due to a problem with the robotic device, Stryker Lim-
ited will also be notified within 2 days of the event tak-
ing place. The chief investigator will record the
following: onset date, complete description of the event,
severity, duration, action taken, and outcome for each
SAE. The chief investigator will also provide regular up-
dates of all SAEs to the London-Bromley Research Eth-
ics Committee, local Health Research Authority, DSMB,
and sponsor.
Data management
On-site monitoring visits shall occur throughout the
course of the clinical study by the chief investigator. The
chief investigator shall permit and assist the sponsor
(should they chose to monitor the study) to carry out
verification of all study forms against data in the source
documents, which shall occur as per the departmental
policy for undertaking such activities. University College
Hospital recognises that there is an obligation to archive
study-related documents at the end of the study. The
study master file will be archived at the University Col-
lege London in accordance with the University College
Hospital Standard Operating Procedure for Archiving of
Investigator Site File (ISF) and Pharmacy Site File (PSF).
It will be archived for a minimum of 5 years from the
study end, and no longer than 30 years from the study
end.
End of protocol treatment
Reasons for going off study protocol include:
Completion of last follow-up visit 2 years after
surgery
Patient non-compliance or withdrawal (the reason
for discontinuation will be recorded in the case re-
port form)
Intercurrent death
All patients included into this study are free to with-
draw from the study at any time without compromise to
their future treatment. On withdrawal, patients will re-
vert to the standard follow-up regimen for routine (non-
study) THA at the study site. The end of study form will
be completed and the reason for withdrawal docu-
mented. This form will also be completed if the patient
is lost to follow-up or dies during the course of the
study. Data to the point of discontinuation will be used
for analysis.
Monitoring
The chief investigator will monitor the progress of the
clinical study in the form of monthly research meetings
for those involved in the trial. The chief investigator will
be responsible for day-to-day monitoring and manage-
ment of the study. The UCLH/UCL/Joint Research Of-
fice, on behalf of UCL as sponsor, will monitor and
conduct random audits on a selection of studies in its
clinical research portfolio. Monitoring and auditing will
be conducted in accordance with the Department of
Health Research Governance Framework for Health &
Social Care (April 2005) and in accordance with the
sponsors monitoring and audit policies and procedures.
As per the protocol, the principal investigator will email
the sponsor twice yearly with the following: delegation
log, adverse event log, deviation log, and any annual pro-
gress reports sent to the Research Ethics Committee.
Any adverse events will also be included in any publica-
tions or presentations relating to the trial.
Peer review
The study protocol has undergone independent external
peer reviewer. The suggestions and recommendations
for improvement to the study design were implemented.
The reviewers and sponsor re-examined the revised
protocol documents and confirmed that all queries and
suggestions had been fully addressed.
Discussion
Accurate restoration of hip biomechanics and implant
positioning in THA are important surgeon-controlled
variables that affect clinical outcomes and implant sur-
vivorship [3,5,6,12,15,18,23]. CO THA is performed
using preoperative radiographic templates and intraoper-
ative anatomical landmarks to manually guide implant
positioning. However, this hand-held conventional
Kayani et al. Trials (2020) 21:776 Page 8 of 10
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technique is associated with 3847% of patients receiv-
ing acetabular components outside of the planned safe
ranges [2,3,8,10]. The development of RO THA has
enabled surgeons to use preoperative CT scans to create
patient-specific surgical plans for achieving optimal im-
plant positioning and hip biomechanics, and an intraop-
erative robotic-arm to execute this plan with a high level
of accuracy [6,14,15,20,25]. This prospective rando-
mised controlled trial compares a comprehensive and
robust range of clinical, functional, and radiological out-
comes between CO THA versus RO THA. All operative
procedures will be undertaken using a standard posterior
approach, sitting and standing spinopelvic radiographs
will be used to assess patient-specific functional pelvic
kinematics, and identical implant designs will be used in
both treatment groups. The findings of this study will
enable an improved understanding of differences in CO
THA versus RO THA with respect to patient satisfac-
tion, functional outcomes, implant survivorship, cost-
effectiveness, and complications.
Trial status
Protocol: version 3.0; date 26 October 2018
Patient recruitment date: 1 December 2018
Estimated completion of the recruitment date: 1 De-
cember 2020
Estimated completion of the final follow-up: 1 Decem-
ber 2022
Registration
Registry name: ClinicalTrials.gov; reference: NCT04095845.
Date registered: 19 September 2019.
URL: https://clinicaltrials.gov/ct2/show/NCT04095845
?cond=mako&draw=2&rank=7.
Abbreviations
CO THA: Conventional manual total hip arthroplasty; DSMB: Data Safety
Monitoring Board; EQ-5D: European Quality of Life questionnaire with 5
dimensions for adults; HHS: Harris hip score; HOOS: Hip disability and
osteoarthritis outcome score; OHS: Oxford hip score; RO THA: Robotic-arm
assisted total hip arthroplasty; SAE: Serious adverse event; SF-12: Short form
health survey of 12 items; UCLA: University of California at Los Angeles hip
score; WOMAC: Western Ontario and McMaster Universities Arthritis Index
Acknowledgements
Nil
Sponsor
The study is sponsored by University College London, 235 Euston Road,
Bloomsbury, London, NW1 2BU, UK (Reference: 241382).
Authorscontributions
BK and JT performed background research, identified gaps in medical
literature, created study objectives and trial design, created CRFs, attended
Research Ethics Committee meeting, helped write the study protocol, and
prepared the National Institute for Health Research (NIHR) Clinical Research
Network (CRN) Industry Costing Template. SK and FSH helped write the
study protocol. The authors read and approved the final manuscript.
Funding
Funding was obtained from Stryker Limited. There are no terms or
conditions to the funding that will impact the study design, data collection,
analysis, interpretation of data, and writing of the manuscript.
Availability of data and materials
The datasets used and/or analysed during the current study are available
from the corresponding author on reasonable request.
Ethics approval and consent to participate
The study has been reviewed and approved for patient recruitment by the
London-Bromley Research Ethics Committee, UK (Reference: 18/LO/0862).
Written informed consent will be obtained from participants during
recruitment on site and prior to data collection. Consent to use the data
collected for scientific reporting and publication will also be obtained at the
same time as the consent to participate.
Consent for publication
The findings of this research will be published in peer-reviewed journals. All
study patients will provide informed consent for the publication of anon-
ymised patient data and study findings. Authorship will reflect the amount
of time spent designing the study, collating the data, analysing the results,
and writing the manuscript. No professional writers will be used. All study
patients will receive a lay summary of the pertinent findings from the study.
Competing interests
FSH reports board membership of the Bone and Joint Journal and the Annals
of the Royal College of Surgeons; consultancy for Smith & Nephew, Corin,
MatOrtho and Stryker; payment for lectures including service on speakers
bureaus for Smith & Nephew and Stryker; and royalties paid by Smith &
Nephew, MatOrtho, Corin and Stryker, all outside the submitted work.
SK reports consultancy, payment for lectures including service on speakers
bureaus, and payment for development of education presentations and
travel/accommodations/meeting expenses for Smith and Nephew and AO,
all outside the submitted work.
All other authors declare no competing interests.
Received: 22 April 2020 Accepted: 27 August 2020
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... However, because of the novelty of this technology, there are limited long-term data on whether these early perioperative benefits translate to long-term patient satisfaction, functional outcomes and implant survival (Robinson et al, 2019;Vermue et al, 2020). Several randomised controlled trials are in progress and will provide more robust evidence on this (Kayani et al, 2020a;2020b;2020c;University Hospital, Grenoble, 2020). ...
Article
Robotic-arm assisted arthroplasty (RAA) has gained popularity over the past decade because of its ability to provide more accurate implant positioning with less surgical trauma than conventional manual arthroplasty. It has shown better early functional outcomes, less postoperative pain and shorter inpatient stays. A multidisciplinary approach is crucial in improving overall outcomes and ensuring this technology is implemented efficiently and safely, but there is limited published literature on the nursing considerations for managing patients undergoing RAA. This article aims to provide a pragmatic approach for nursing care in the pre-, intra-, and postoperative phases of RAA.
Article
Full-text available
Background Robotic-assisted total hip arthroplasty (THA) allows for accurate preoperative planning and component positioning, potentially enhancing implant survival and long-term outcomes. The relative efficacy and safety of robotic-assisted and conventional THA, however, are unclear. This systematic review and meta-analysis compared the safety and efficacy of robotic-assisted and conventional THA. Methods Medline, Embase and the Cochrane Library were comprehensively searched in September 2017 to identify studies comparing the safety and efficacy of robotic-assisted and conventional THA. Seven studies were included. Data of interest were extracted and analysed using Review Manager 5.3. Results The seven included studies involved 1516 patients, with 522 undergoing robotic-assisted and 994 undergoing conventional THA. Compared with conventional THA, robotic-assisted THA was associated with longer surgical time (not significant); lower intraoperative complication rates (OR: 0.12, 95% CI: 0.05 to 0.34, p<0.0001 I²); better cup placement, stem placement and global offset and a higher rate of heterotopic ossifications. Functional scores, limb length discrepancy and rates of revision and stress shielding were similar in the two groups. The relative amount of blood loss was unclear. Conclusion The results of this meta-analysis suggest that robotic-assisted THA has certain advantages over conventional THA, including the results of component positioning and rates of intraoperative complications. Additional comparative studies are required to determine the long-term clinical outcomes of robotic-assisted THA.
Article
Full-text available
Background and purpose There is no consensus on the association between global femoral offset (FO) and outcome after total hip arthroplasty (THA). We assessed the association between FO and patients’ reported hip function, quality of life, and abductor muscle strength. Patients and methods We included 250 patients with unilateral hip osteoarthritis who underwent a THA. Before the operation, the patient’s reported hip function was evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and quality of life was evaluated with EQ-5D. At 1-year follow-up, the same scores and also hip abductor muscle strength were measured. 222 patients were available for follow-up. These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment). Results All 3 groups improved (p < 0.001). The crude results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups. Interpretation A reduction in global FO of more than 5 mm after THA appears to have a negative association with abductor muscle strength of the operated hip, and should therefore be avoided.
Article
Full-text available
Acetabular cup positioning, leg-length discrepancy, and global offset are important parameters associated with outcomes following total hip arthroplasty (THA). Deviation from an accepted range of values can lead to significant complications, including dislocation, leg-length discrepancy, impingement, accelerated bearing surface wear, and revisions. The purpose of this study was to assess whether robotic-assisted THA was reliable in predicting radiographic measurements of cup inclination and anteversion, leg-length change, and global offset change. All 61 robotic-assisted THAs that met the inclusion and exclusion criteria were performed by a single surgeon through a mini-posterior approach. Data provided by the robot were collected prospectively, and radiographic data were collected retrospectively by 2 blinded independent reviewers. The cohort in this study consisted of 27 male and 34 female patients, with an average age of 60.5 years. A strong inter- and intraobserver correlation was found for the radiographic measurements of cup inclination, cup anteversion, leg-length discrepancy, and global offset (r>0.8 with P<.001 for all). Ninety-six point seven percent of robotic-measured inclination angles and 98.4% of robotic-measured anteversion angles were within 10° of radiographic measurements. One hundred percent of robotic-measured leg-length change and 91.8% of robotic-measured global offset change were within 10 mm of radiographic measurements. Robotic-assisted THA showed good predictive value for cup inclination and anteversion angles and measurements of leg-length change and global offset change done postoperatively on plain radiographs. Further refinement of the robotic system would make it more accurate in predicting the postoperative parameters mentioned. [Orthopedics. 2015; 38(1):e31-e37.]. Copyright 2015, SLACK Incorporated.
Article
Background: Robotic-arm assisted surgery aims to reduce manual errors and improve the accuracy of implant positioning and orientation during total hip arthroplasty (THA). The objective of this study was to assess the surgical team's learning curve for robotic-arm assisted acetabular cup positioning during THA. Methods: This prospective cohort study included 100 patients with symptomatic hip osteoarthritis undergoing primary total THA performed by a single surgeon. This included 50 patients receiving conventional manual THA and 50 patients undergoing robotic-arm assisted acetabular cup positioning during THA. Independent observers recorded surrogate markers of the learning curve including operative times, confidence levels amongst the surgical team using the state-trait anxiety inventory (STAI) questionnaire, accuracy in restoring native hip biomechanics, acetabular cup positioning, leg-length discrepancy, and complications within 90 days of surgery. Results: Cumulative summation (CUSUM) analysis revealed robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for achieving operative times (p < 0.001) and surgical team confidence levels (p < 0.001) comparable to conventional manual THA. There was no learning curve of robotic-arm assisted THA for accuracy of achieving the planned horizontal (p = 0.83) and vertical (p = 0.71) centres of rotation, combined offset (p = 0.67), cup inclination (p = 0.68), cup anteversion (p = 0.72), and correction of leg-length discrepancy (p = 0.61). There was no difference in postoperative complications between the two treatment groups. Conclusions: Integration of robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for operative times and surgical team confidence levels but there was no learning curve effect for accuracy in restoring native hip biomechanics or achieving planned acetabular cup positioning and orientation.
Article
Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA. Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA. Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA. Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs. Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness. Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088
Article
Objectives The primary objective of this study was to compare accuracy in restoring the native centre of hip rotation in patients undergoing conventional manual total hip arthroplasty (THA) versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, component inclination, component version, and leg-length correction. Materials and Methods This prospective cohort study included 50 patients undergoing conventional manual THA and 25 patients receiving robotic-arm assisted THA. Patients undergoing conventional manual THA and robotic-arm assisted THA were well matched for age (mean age, 69.4 years (sd 5.2) vs 67.5 years (sd 5.8) (p = 0.25); body mass index (27.4 kg/m ² (sd 2.1) vs 26.9 kg/m ² (sd 2.2); p = 0.39); and laterality of surgery (right = 28, left = 22 vs right = 12, left = 13; p = 0.78). All operative procedures were undertaken by a single surgeon using the posterior approach. Two independent blinded observers recorded all radiological outcomes of interest using plain radiographs. Results The correlation coefficient was 0.92 (95% confidence interval (CI) 0.88 to 0.95) for intraobserver agreement and 0.88 (95% CI 0.82 to 0.94) for interobserver agreement in all study outcomes. Robotic THA was associated with improved accuracy in restoring the native horizontal (p < 0.001) and vertical (p < 0.001) centres of rotation, and improved preservation of the patient’s native combined offset (p < 0.001) compared with conventional THA. Robotic THA improved accuracy in positioning of the acetabular component within the combined safe zones of inclination and anteversion described by Lewinnek et al (p = 0.02) and Callanan et al (p = 0.01) compared with conventional THA. There was no difference between the two treatment groups in achieving the planned leg-length correction (p = 0.10). Conclusion Robotic-arm assisted THA was associated with improved accuracy in restoring the native centre of rotation, better preservation of the combined offset, and more precise acetabular component positioning within the safe zones of inclination and anteversion compared with conventional manual THA.
Article
Aims: The aim of this study was to evaluate the accuracy of implant placement when using robotic assistance during total hip arthroplasty (THA). Patients and methods: A total of 20 patients underwent a planned THA using preoperative CT scans and robotic-assisted software. There were nine men and 11 women (n = 20 hips) with a mean age of 60.8 years (sd 6.0). Pelvic and femoral bone models were constructed by segmenting both preoperative and postoperative CT scan images. The preoperative anatomical landmarks using the robotic-assisted system were matched to the postoperative 3D reconstructions of the pelvis. Acetabular and femoral component positions as measured intraoperatively and postoperatively were evaluated and compared. Results: The system reported accurate values for reconstruction of the hip when compared to those measured postoperatively using CT. The mean deviation from the executed overall hip length and offset were 1.6 mm (sd 2.9) and 0.5 mm (sd 3.0), respectively. Mean combined anteversion was similar and correlated between intraoperative measurements and postoperative CT measurements (32.5°, sd 5.9° versus 32.2°, sd 6.4°; respectively; R2 = 0.65; p < 0.001). There was a significant correlation between mean intraoperative (40.4°, sd 2.1°) acetabular component inclination and mean measured postoperative inclination (40.12°, sd 3.0°, R2 = 0.62; p < 0.001). There was a significant correlation between mean intraoperative version (23.2°, sd 2.3°), and postoperatively measured version (23.0°, sd 2.4°; R2 = 0.76; p < 0.001). Preoperative and postoperative femoral component anteversion were significantly correlated with one another (R2 = 0.64; p < 0.001). Three patients had CT scan measurements that differed substantially from the intraoperative robotic measurements when evaluating stem anteversion. Conclusion: This is the first study to evaluate the success of hip reconstruction overall using robotic-assisted THA. The overall hip reconstruction obtained in the operating theatre using robotic assistance accurately correlated with the postoperative component position assessed independently using CT based 3D modelling. Clinical correlation during surgery should continue to be practiced and compared with observed intraoperative robotic values. Cite this article: Bone Joint J 2018;100-B:1303-9.
Article
Background: Component malposition in total hip arthroplasty (THA) contributes to instability and early failure. Robotic-assisted total hip arthroplasty (rTHA) utilizes CT-based planning with haptically-guided bone preparation and implant insertion to optimize component position accuracy. This study compared acetabular component position and postoperative complications following manual THA (mTHA) with rTHA. Materials and methods: Consecutive primary THAs performed by one surgeon at three intervals were analyzed in this retrospective cohort study: the initial 100 consecutive manual THAs (mTHA) in clinical practice (year 2000), the last consecutive 100 mTHA before rTHA introduction (year 2011), and the first consecutive 100 rTHA (year 2012). Acetabular abduction (AAB) and anteversion (AAV) angles were measured using validated software. The Lewinnek safe zone was used to define accuracy (AAB 40°±10° and AAV 15°±10°). Comparisons included operative time, estimated blood loss (EBL), infection rate, and dislocation rate. Results: The rate of acetabular component placement within Lewinnek safe zone was the highest in the rTHA cohort (77%), followed by late mTHA (45%) and early mTHA (30%) (p<0.001). Robotic-assisted THA resulted in an additional 71% improvement in accuracy in the first year of use (p<0.001). Dislocation rate was 5% with early mTHA, 3% in the late mTHA cohort, and 0% in the rTHA cohort within the first two years postoperatively. There were no statistically significant differences in the rate of infection between groups. Conclusion: Robotic-assisted THA improved acetabular component accuracy and reduced dislocation rates when compared with mTHA. Further study is needed to determine if similar improvements will be noted in larger multicenter studies using alternative surgical approaches.
Article
Aims: The Advance Medial-Pivot total knee arthroplasty (TKA) was designed to reflect contemporary data regarding the kinematics of the knee. We wished to examine the long-term results obtained with this prosthesis by extending a previous evaluation. Patients and methods: We retrospectively evaluated prospectively collected data from 225 consecutive patients (41 men and 184 women; mean age at surgery 71 years, 52 to 84) who underwent 284 TKAs with a mean follow-up of 13.4 years (11 to 15). Implant failure, complication rate, clinical (both subjective and objective) and radiological outcome were assessed. Pre- and post-operative clinical and radiographic data were available at regular intervals for all patients. A total of ten patients (4.4%; ten TKAs) were lost to follow-up. Results: Survival analysis at 15 years showed a cumulative success rate of 97.3% (95% confidence interval (CI) 96.7 to 97.9) for revision for any reason, of 96.4% (95% CI 95.2 to 97.6) for all operations, and 98.8% (95% CI 98.2 to 99.4) for aseptic loosening as an end point. Three TKAs (1.06%) were revised due to aseptic loosening, two (0.7%) due to infection, one (0.35%) due to instability and one (0.35%) due to a traumatic dislocation. All patients showed a statistically significant improvement on the Knee Society Score (p = 0.001), Western Ontario and McMaster University Osteoarthritis Index (p = 0.001), Short Form-12 (p = 0.01), and Oxford Knee Score (p = 0.01). A total of 207 patients (92%) were able to perform age appropriate activities with a mean flexion of the knee of 117° (85° to 135°) at final follow-up. Conclusion: This study demonstrates satisfactory functional and radiographic long-term results for this implant. Cite this article: Bone Joint J 2016;98-B:1050-5.
Article
The objective was to evaluate whether total hip arthroplasty (THA) using haptic robot assistance restores hip geometry better than the free-hand technique. Twelve robot-assisted and 14 free-hand unilateral THA patients underwent CT scan for three-dimensional (3D) hip models. The anteversion, inclination and hip joint centre locations of the native and implanted hips in each patient were quantified and compared. Significant increase of combined anteversion by 19.1 ± 11.7° and 23.5 ± 23.6° and decrease of cup inclination by 16.5 ± 6.0° and 10.2 ± 6.8° were observed in the robot-assisted and the free-hand THAs, respectively. Less variation in the difference of the component orientations (max 11.1 vs 18.3°) and the femoral head centre (max 4.5 vs 6.3 mm) were found in the robot-assisted group. This study demonstrated that neither robot-assisted nor free-hand THAs had fully restored native hip geometry. However, the higher precision of the robot-assisted THA suggested that it has potential utility in restoring the native hip geometry. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.