This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups.Aims
Methods
Many authors have recommended undercorrection of the deformity when carrying out
Failure of a
The mobile bearing Oxford unicompartmental knee arthroplasty (OUKA) is recommended to be performed with the leg in the hanging leg (HL) position, and the thigh placed in a stirrup. This comparative cadaveric study assesses implant positioning and intraoperative kinematics of OUKA implanted either in the HL position or in the supine leg (SL) position. A total of 16 fresh-frozen knees in eight human cadavers, without macroscopic anatomical defects, were selected. The knees from each cadaver were randomized to have the OUKA implanted in the HL or SL position.Aims
Methods
There is a large amount of evidence available
about the relative merits of unicompartmental and total knee arthroplasty
(UKA and TKA). Based on the same evidence, different people draw
different conclusions and as a result, there is great variability
in the usage of UKA. The revision rate of UKA is much higher than TKA and so some
surgeons conclude that UKA should not be performed. Other surgeons
believe that the main reason for the high revision rate is that
UKA is easy to revise and, therefore, the threshold for revision
is low. They also believe that UKA has many advantages over TKA
such as a faster recovery, lower morbidity and mortality and better
function. They therefore conclude that UKA should be undertaken
whenever appropriate. The solution to this argument is to minimise the revision rate
of UKA, thereby addressing the main disadvantage of UKA. The evidence
suggests that this will be achieved if surgeons use UKA for at least
20% of their knee arthroplasties and use implants that are appropriate
for these broad indications. Cite this article:
The primary aim of this study was to determine the surgical team’s
learning curve for introducing robotic-arm assisted unicompartmental
knee arthroplasty (UKA) into routine surgical practice. The secondary
objective was to compare accuracy of implant positioning in conventional
jig-based UKA versus robotic-arm assisted UKA. This prospective single-surgeon cohort study included 60 consecutive
conventional jig-based UKAs compared with 60 consecutive robotic-arm
assisted UKAs for medial compartment knee osteoarthritis. Patients
undergoing conventional UKA and robotic-arm assisted UKA were well-matched
for baseline characteristics including a mean age of 65.5 years
(Aims
Patients and Methods
The significance of weight in the indications
for
Whether to use total or unicompartmental knee
replacement (TKA/UKA) for end-stage knee osteoarthritis remains controversial.
Although UKA results in a faster recovery, lower rates of morbidity
and mortality and fewer complications, the long-term revision rate
is substantially higher than that for TKA. The effect of each intervention on
patient-reported outcome remains unclear. The aim of this study
was to determine whether six-month patient-reported outcome measures
(PROMs) are better in patients after TKA or UKA, using data from
a large national joint registry (NJR). We carried out a propensity score-matched cohort study which
compared six-month PROMs after TKA and UKA in patients enrolled
in the NJR for England and Wales, and the English national PROM
collection programme. A total of 3519 UKA patients were matched
to 10 557 TKAs. The mean six-month PROMs favoured UKA: the Oxford Knee Score
was 37.7 (95% confidence interval (CI) 37.4 to 38.0) for UKA and
36.1 (95% CI 35.9 to 36.3) for TKA; the mean EuroQol EQ-5D index
was 0.772 (95% CI 0.764 to 0.780) for UKA and 0.751 (95% CI 0.747
to 0.756) for TKA. UKA patients were more likely to achieve excellent
results (odds ratio (OR) 1.59, 95% CI 1.47 to 1.72, p <
0.001)
and to be highly satisfied (OR 1.27, 95% CI 1.17 to 1.39, p <
0.001), and
were less likely to report complications than those who had undergone
TKA. UKA gives better early patient-reported outcomes than TKA; these
differences are most marked for the very best outcomes. Complications
and readmission are more likely after TKA. Although the data presented
reflect the short-term outcome, they suggest that the high revision
rate for UKA may not be because of poorer clinical outcomes. These
factors should inform decision-making in patients eligible for either
procedure. Cite this article:
This prospective study reports the 15-year survival and ten-year
functional outcome of a consecutive series of 1000 minimally invasive
Phase 3 Oxford medial UKAs (818 patients, 393 men, 48%, 425 women,
52%, mean age 66 years; 32 to 88). These were implanted by two surgeons
involved with the design of the prosthesis to treat anteromedial
osteoarthritis and spontaneous osteonecrosis of the knee, which
are recommended indications. Patients were prospectively identified
and followed up independently for a mean of 10.3 years (5.3 to 16.6). At ten years, the mean Oxford Knee Score was 40 (standard deviation
( This is the only large series of minimally invasive UKAs with
15-year survival data. The results support the continued use of
minimally invasive UKA for the recommended indications. Cite this article:
We recently published a paper comparing the incidence
of adverse outcomes after unicompartmental and total knee arthroplasty
(UKA and TKA). The conclusion of this study, which was in favour
of UKA, was dismissed as “biased” in a review in Cite this article:
Radiological assessment of total and unicompartmental
knee replacement remains an essential part of routine care and follow-up.
Appreciation of the various measurements that can be identified
radiologically is important. It is likely that routine plain radiographs
will continue to be used, although there has been a trend towards
using newer technologies such as CT, especially in a failing knee,
where it provides more detailed information, albeit with a higher
radiation exposure. The purpose of this paper is to outline the radiological parameters
used to evaluate knee replacements, describe how these are measured
or classified, and review the current literature to determine their
efficacy where possible.
Altered alignment and biomechanics are thought to contribute to the progression of osteoarthritis (OA) in the native compartments after medial unicompartmental knee arthroplasty (UKA). The aim of this study was to evaluate the bone activity and remodelling in the lateral tibiofemoral and patellofemoral compartment after medial mobile-bearing UKA. In total, 24 patients (nine female, 15 male) with 25 medial Oxford UKAs (13 left, 12 right) were prospectively followed with sequential 99mTc-hydroxymethane diphosphonate single photon emission CT (SPECT)/CT preoperatively and at one and two years postoperatively, along with standard radiographs and clinical outcome scores. The mean patient age was 62 years (40 to 78) and the mean body mass index (BMI) was 29.7 kg/m2 (23.6 to 42.2). Mean osteoblastic activity was evaluated using a tracer localization scheme with volumes of interest (VOIs). Normalized mean tracer values were calculated as the ratio between the mean tracer activity in a VOI and background activity in the femoral diaphysis.Aims
Patients and Methods
Mobile-bearing unicompartmental knee replacements
(UKRs) with a flat tibial plateau have not performed well in the
lateral compartment, owing to a high dislocation rate. This led
to the development of the Domed Lateral Oxford UKR (Domed OUKR)
with a biconcave bearing. The aim of this study was to assess the
survival and clinical outcomes of the Domed OUKR in a large patient
cohort in the medium term. We prospectively evaluated 265 consecutive knees with isolated
disease of the lateral compartment and a mean age at surgery of
64 years (32 to 90). At a mean follow-up of four years ( The Domed Lateral OUKR gives good clinical outcomes, low re-operation
and revision rates and a low dislocation rate in patients with isolated
lateral compartmental disease, in the hands of the designer surgeons. Cite this article:
This prospective study describes the outcome of the first 1000 phase 3 Oxford medial unicompartmental knee replacements (UKRs) implanted using a minimally invasive surgical approach for the recommended indications by two surgeons and followed up independently. The mean follow-up was 5.6 years (1 to 11) with 547 knees having a minimum follow-up of five years. At five years their mean Oxford knee score was 41.3 ( The incidence of implant-related re-operations was 2.9%; of these 29 re-operations two were revisions requiring revision knee replacement components with stems and wedges, 17 were conversions to a primary total knee replacement, six were open reductions for dislocation of the bearing, three were secondary lateral UKRs and one was revision of a tibial component. The most common reason for further surgical intervention was progression of arthritis in the lateral compartment (0.9%), followed by dislocation of the bearing (0.6%) and revision for unexplained pain (0.6%). If all implant-related re-operations are considered failures, the ten-year survival rate was 96% (95% confidence interval, 92.5 to 99.5). If only revisions requiring revision components are considered failures the ten-year survival rate is 99.8% (confidence interval 99 to 100). This is the largest published series of UKRs implanted through a minimally invasive surgical approach and with ten-year survival data. The survival rates are similar to those obtained with a standard open approach whereas the function is better. This demonstrates the effectiveness and safety of a minimally invasive surgical approach for implanting the Oxford UKR.
The most common reasons for revision of unicompartmental
knee arthroplasty (UKA) are loosening and pain. Cementless components
may reduce the revision rate. The aim of this study was to compare
the fixation and clinical outcome of cementless and cemented Oxford
UKAs. A total of 43 patients were randomised to receive either a cemented
or a cementless Oxford UKA and were followed for two years with
radiostereometric analysis (RSA), radiographs aligned with the bone–implant
interfaces and clinical scores. The femoral components migrated significantly during the first
year (mean 0.2 mm) but not during the second. There was no significant
difference in the extent of migration between cemented and cementless
femoral components in either the first or the second year. In the
first year the cementless tibial components subsided significantly
more than the cemented components (mean 0.28 mm ( As second-year migration is predictive of subsequent loosening,
and as radiolucency is suggestive of reduced implant–bone contact,
these data suggest that fixation of the cementless components is
at least as good as, if not better than, that of cemented devices. Cite this article:
Because there have been no standard methods to determine pre-operatively
the thickness of resection of the proximal tibia in unicompartmental
knee arthroplasty (UKA), information about the relationship between
the change of limb alignment and the joint line elevation would
be useful for pre-operative planning. The purpose of this study
was to clarify the correlation between the change of limb alignment
and the change of joint line height at the medial compartment after
UKA. A consecutive series of 42 medial UKAs was reviewed retrospectively.
These patients were assessed radiographically both pre- and post-operatively
with standing anteroposterior radiographs. The thickness of bone
resection at the proximal tibia and the distal femur was measured
radiographically. The relationship between the change of femorotibial
angle (δFTA) and the change of joint line height, was analysed.Objectives
Methods
We studied whether the presence of lateral osteophytes
on plain radiographs was a predictor for the quality of cartilage
in the lateral compartment of patients with varus osteoarthritic
of the knee (Kellgren and Lawrence grade 2 to 3). The baseline MRIs of 344 patients from the Osteoarthritis Initiative
(OAI) who had varus osteoarthritis (OA) of the knee on hip-knee-ankle
radiographs were reviewed. Patients were categorised using the Osteoarthritis
Research Society International (OARSI) osteophyte grading system
into 174 patients with grade 0 (no osteophytes), 128 grade 1 (mild
osteophytes), 28 grade 2 (moderate osteophytes) and 14 grade 3 (severe
osteophytes) in the lateral compartment (tibia). All patients had
Kellgren and Lawrence grade 2 or 3 arthritis of the medial compartment.
The thickness and volume of the lateral cartilage and the percentage
of full-thickness cartilage defects in the lateral compartment was
analysed. There was no difference in the cartilage thickness or cartilage
volume between knees with osteophyte grades 0 to 3. The percentage
of full-thickness cartilage defects on the tibial side increased
from <
2% for grade 0 and 1 to 10% for grade 3. The lateral compartment cartilage volume and thickness is not
influenced by the presence of lateral compartment osteophytes in
patients with varus OA of the knee. Large lateral compartment osteophytes
(grade 3) increase the likelihood of full-thickness cartilage defects
in the lateral compartment. Cite this article:
Symptomatic and asymptomatic deep-vein thrombosis
(DVT) is a common complication of knee replacement, with an incidence
of up to 85% in the absence of prophylaxis. National guidelines
for thromboprophylaxis in knee replacement are derived from total
knee replacement (TKR) data. No guidelines exist specific to unicompartmental knee
replacement (UKR). We investigated whether the type of knee arthroplasty
(TKR or UKR) was related to the incidence of DVT and discuss the
applicability of existing national guidelines for prophylaxis following
UKR. Data were collected prospectively on 3449 knee replacements,
including procedure type, tourniquet time, surgeon, patient age,
use of drains and gender. These variables were related to the incidence
of symptomatic DVT. The overall DVT rate was 1.6%. The only variable that had an
association with DVT was operation type, with TKR having a higher
incidence than UKR (2.2% TKR and UKR patients have different risk profiles for symptomatic
DVT. The risk-benefit ratio for TKR that has been used to produce
national guidelines may not be applicable to UKR. Further research
is required to establish the most appropriate form of prophylaxis
for UKR.