Multiple reports suggest good outcome results following unicompartmental knee replacement (UKR). However, several authors report technically difficult revision surgery secondary to osseous defects. We reviewed clinical outcomes following revision total knee replacement for failed UKR and analysed the reasons for failure and the technical aspects of the revision surgery.

Between 2003 and 2009, thirty three revisions from unicompartmental knee replacement to total knee replacement were performed in thirty two patients at a single centre. Demographics, indications for the primary and revision procedures, details of the revised prosthesis including augments and any technical difficulties or complications were noted. Patient assessment included range of motion and the functional status of the affected knee in the form of the Oxford knee score questionnaire. Statistical analysis was performed with the Student t test.

All 33 revision knees were available for prospective clinical and radiological follow-up. The minimum duration of follow-up after revision surgery was 1 year (mean 3 years, range 1 – 7 years). The median interval between the original unicompartmental knee replacements to revision surgery was 19 months (range 2 – 159 months). The predominant cause of failure was aseptic loosening (50%). Other reasons included persistent pain (21%), dislocated meniscus (18%), mal-alignment (7%) and progression of symptomatic osteoarthritis in another compartment (4%). 18 of the 33 revision procedures required additional augments. During the revision surgery, 11 knees required a long tibial stem while 1 required a long femoral stem. 10 knees required medial tibial wedge augmentation; bone graft was used in 6 knees while a metal wedge augment was used in 4 to fill significant osseous defects. At the time of follow-up, range of movement averaged 103 degrees (range 70 – 120). The mean one year Oxford knee score, was 29 compared to 39 for primary total knee replacements performed during the same period in a comparable sample group of patients at our institute (p < 0.001). Three patients continued to have pain and two required re-revision; one for infection and one for loosening.

Aseptic loosening was the commonest mode of failure. Of the UKRs revised to TKRs, 90% were revised within 5 years. The majority of revisions required additional constructs. Oxford Knee Scores after revision surgery were inferior to those for primary TKR. The role of UKR needs to be more clearly defined.

Introduction

There has been renewed interest in the unicompartmental knee arthroplasty with reports of good long term outcomes. Advantages over a more extensive knee replacement include: preservation of bone stock, retention of both cruciate ligaments, preservation of other compartments and better knee kinematics. However, a number of authors have commented on the problem of osseous defects requiring technically difficult revision surgery. Furthermore, a number of recent national register studies have shown inferior survivorship when compared to total knee arthroplasty.

The purpose of this study was to review the cases of our patients who had a revision total knee arthroplasty for failed unicompartmental knee arthroplasty. To determine the reason for failure, describe the technical difficulties during revision surgery and record the clinical outcomes of the revision arthroplasties.

Introduction: Stiffness following total knee arthroplasty is a disabling problem resulting in pain and reduced function. Prevalence is not well defined and although various treatment modalities including manipulation, arthrolysis and revision surgery has been proposed with varying degrees of success for reduced flexion, these Methods: are deemed to be of limited value in fixed flexion deformity (FFD). There is limited literature on the natural history of FFD which is important to the decision process. The aim of our study was to evaluate the natural course of FFD following primary total knee arthroplasty.

Methods: Prospective review of a consecutive series of 1768 patients who underwent primary total knee arthroplasty over a 7 year (2001 to 2008) period. Demographic data included post-operative range of motion; type of prosthesis used, treatment modalities for stiffness and the final range of motion were recorded. FFD was defined as class 1(hyperextension to 0), Class 2 (1–10 degrees), Class 3(11–20 degrees) and Class 4(> 20 degrees).

All patients were reviewed by an independent reviewer (senior physiotherapist). All patients were followed from 6 weeks post surgery until FFD completely resolved or improved to patient satisfaction. Patients with infection, stiffness treated with manipulation or revision surgery were excluded from the study. Patients lost to follow-up were noted.

Results: Of the 1768 patients evaluated, 180 (10.2%) presented with a FFD. A total number of 18 patients were excluded from the study and 16 were lost to follow up. None (0%) were class 1, 134 (91.8%) were class 2, 10 (6.9%) were class 3 and 2 (1.4%) were class 4. The FFD group had a mean age of 60.5. Follow up period ranged from 1.3 to 63.3 months and the FFD improved from a mean of 8.16 degrees to 0.15 degrees (p< 0.001). In 94.5% patients the FFD completely resolved (i.e. < 5 deg) at a mean of 9.76 months. In the remaining 5.5% of patients, FFD improved from a mean of 16.4 to 6.9 degrees at a mean follow up of 15.5 months and was found to cause no functional deficit.

Conclusion: The overall prevalence of fixed flexion deformity is 10.2 % with only 0.7% in Class 3 and Class 4, which is comparable with the literature. The majority of patients will see a resolution of their fixed flexion deformity in less than 10 months with routine post operative physiotherapy. The small number of patients left with a residual FFD did not appear to suffer a functional deficit. Patients found to have a post operative FFD should be reassured and encouraged to participate in a standardised post operative physiotherapy regime.