To report mid- to long-term results of Oxford mobile bearing domed lateral unicompartmental knee arthroplasty (UKA), and determine the effect of potential contraindications on outcome. A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and the presence of full-thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated.Aims
Methods
The primary stability of the cementless Oxford Unicompartmental Knee Replacement (OUKR) relies on interference fit (or press fit). Insufficient interference may cause implant loosening, whilst excessive interference could cause bone damage and fracture. The aim of this study was to identify the optimal interference fit by measuring the force required to seat the tibial component of the cementless OUKR (push-in force) and the force required to remove the component (pull-out force). Six cementless OUKR tibial components were implanted in 12 new slots prepared on blocks of solid polyurethane foam (20 pounds per cubic foot (PCF), Sawbones, Malmo, Sweden) with a range of interference of 0.1 mm to 1.9 mm using a Dartec materials testing machine HC10 (Zwick Ltd, Herefordshire, United Kingdom) . The experiment was repeated with cellular polyurethane foam (15 PCF), which is a more porous analogue for trabecular bone.Objectives
Materials and Methods
It is not clear whether anterior knee pain and osteoarthritis
(OA) of the patellofemoral joint (PFJ) are contraindications to
medial unicompartmental knee arthroplasty (UKA). Our aim was to
investigate the long-term outcome of a consecutive series of patients,
some of whom had anterior knee pain and PFJ OA managed with UKA. We assessed the ten-year functional outcomes and 15-year implant
survival of 805 knees (677 patients) following medial mobile-bearing
UKA. The intra-operative status of the PFJ was documented and, with
the exception of bone loss with grooving to the lateral side, neither
the clinical or radiological state of the PFJ nor the presence of
anterior knee pain were considered a contraindication. The impact
of radiographic findings and anterior knee pain was studied in a
subgroup of 100 knees (91 patients).Aims
Patients and Methods
While medial unicompartmental knee arthroplasty (UKA) is indicated
for patients with full-thickness cartilage loss, it is occasionally
used to treat those with partial-thickness loss. The aim of this
study was to investigate the five-year outcomes in a consecutive
series of UKAs used in patients with partial thickness cartilage
loss in the medial compartment of the knee. Between 2002 and 2014, 94 consecutive UKAs were undertaken in
90 patients with partial thickness cartilage loss and followed up
independently for a mean of six years (1 to 13). These patients
had partial thickness cartilage loss either on both femur and tibia
(13 knees), or on either the femur or the tibia, with full thickness
loss on the other surface of the joint (18 and 63 knees respectively).
Using propensity score analysis, these patients were matched 1:2 based
on age, gender and pre-operative Oxford Knee Score (OKS) with knees
with full thickness loss on both the femur and tibia. The functional
outcomes, implant survival and incidence of re-operations were assessed
at one, two and five years post-operatively. A subgroup of 36 knees
in 36 patients with partial thickness cartilage loss, who had pre-operative
MRI scans, was assessed to identify whether there were any factors
identified on MRI that predicted the outcome.Aims
Patients and Methods
An evidence-based radiographic Decision Aid for meniscal-bearing
unicompartmental knee arthroplasty (UKA) has been developed and
this study investigates its performance at an independent centre. Pre-operative radiographs, including stress views, from a consecutive
cohort of 550 knees undergoing arthroplasty (UKA or total knee arthroplasty;
TKA) by a single-surgeon were assessed. Suitability for UKA was
determined using the Decision Aid, with the assessor blinded to
treatment received, and compared with actual treatment received, which
was determined by an experienced UKA surgeon based on history, examination,
radiographic assessment including stress radiographs, and intra-operative
assessment in line with the recommended indications as described
in the literature.Aims
Patients and Methods
The cementless Oxford unicompartmental knee replacement
has been demonstrated to have superior fixation on radiographs and
a similar early complication rate compared with the cemented version.
However, a small number of cases have come to our attention where,
after an apparently successful procedure, the tibial component subsides into
a valgus position with an increased posterior slope, before becoming
well-fixed. We present the clinical and radiological findings of
these six patients and describe their natural history and the likely
causes. Two underwent revision in the early post-operative period,
and in four the implant stabilised and became well-fixed radiologically with
a good functional outcome. This situation appears to be avoidable by minor modifications
to the operative technique, and it appears that it can be treated
conservatively in most patients. Cite this article:
The aim of this study was to review the early
outcome of the Femoro-Patella Vialla (FPV) joint replacement. A
total of 48 consecutive FPVs were implanted between December 2007
and June 2011. Case-note analysis was performed to evaluate the
indications, operative histology, operative findings, post-operative
complications and reasons for revision. The mean age of the patients
was 63.3 years (48.2 to 81.0) and the mean follow-up was
25.0 months (6.1 to 48.9). Revision was performed in seven (14.6%)
at a mean of 21.7 months, and there was one re-revision. Persistent
pain was observed in three further patients who remain unrevised.
The reasons for revision were pain due to progressive tibiofemoral
disease in five, inflammatory arthritis in one, and patellar fracture following
trauma in one. No failures were related to the implant or the technique.
Trochlear dysplasia was associated with a significantly lower rate
of revision (5.9% Focal patellofemoral osteoarthritis secondary to trochlear dysplasia
should be considered the best indication for patellofemoral replacement.
Standardised radiological imaging, with MRI to exclude overt tibiofemoral
disease should be part of the pre-operative assessment, especially
for the non-dysplastic knee. Cite this article:
Narrow, well-defined radiolucent lines commonly observed at the bone-implant interface of unicompartmental knee replacement tibial components have been referred to as physiological radiolucencies. These should be distinguished from pathological radiolucencies, which are poorly defined, wide and progressive, and associated with loosening and infection. We studied the incidence and clinical significance of tibial radiolucent lines in 161 Oxford unicondylar knee replacements five years after surgery. All the radiographs were aligned with fluoroscopic control to obtain views parallel to the tibial tray to reveal the tibial bone-implant interface. We found that 49 knees (30%) had complete, 52 (32%) had partial and 60 (37%) had no radiolucent lines. There was no relationship between the incidence of radiolucent lines and patient factors such as gender, body mass index and activity, or operative factors including the status of the anterior cruciate ligament and residual varus deformity. Nor was any statistical relationship established between the presence of radiolucent lines and clinical outcome, particularly pain, assessed by the Oxford Knee score and the American Knee Society score. We conclude that radiolucent lines are common after Oxford unicompartmental knee replacement but that their aetiology remains unclear. Radiolucent lines were not a source of adverse symptoms or pain. Therefore, when attempting to identify a source of postoperative pain after Oxford unicompartmental knee replacement the presence of a physiological radiolucency should be ignored.
