A number of studies suggest revision of unicompartmental knee replacement (UKR) to total knee replacement (TKR) is straightforward. We hypothesise that this is not always the case in terms of complexity, cost and clinical outcome.

We identified 23 consecutive patients revised from UKR to TKR by 2 consultant surgeons (2005–2008). These were matched by age, sex and comorbidity to a cohort of primary TKRs (42 patients) performed during the same period. Data were collected regarding demographics, cost (surgical time & implants) and 1 & 5-year follow-up of clinical outcome (OKS) and outpatients attended.

There was no statistically significant difference in cost of implants for revision UKR to TKR vs. primary TKR (p=0.08), however operative time was significantly higher in the revision group. One year mean OKS was significantly higher in the primary TKR group (mean 30 vs. 23 p=0.03), but 5-year follow up showed no significant difference (mean OKS 27 vs. 32 p=0.20). The revision group had statistically significantly greater number of follow-up appointments (mean 6 Vs. 2 p<0.0001).

Revision of UKR to TKR is not a universally straightforward procedure, carrying significant overall cost implications. Clinical outcomes, although significantly different at 1 year are almost the same at 5 years.

Introduction

Menisci performs multiple functions in the knee.'These depend largely on the structural integrity of the meniscus. Arthroscopic partial menisectomy is the treatment of choice for meniscal tears in adults. There is conflicting evidence about the progression of degenerative changes in the medial or lateral compartment of the knee following menisectomy.

Classical AO teaching recommends that a syndesmosis screw should be inserted at 25 to 30 degree angle to the coronal plane of the ankle. In practice accurately judging the 25/30 degree angle can be difficult, and there are several reports based on post operative CT scans demonstrating that a significant minority of patients have poorly operatively reduced syndesmotic injuries.

The CT scans of 200 normal ankles in one hundred individuals which had been performed as part a CT angiogram were retrospectively examined. The centroid of the fibula and tibia in the axial plane 15mm proximal to the talar dome was calculated. Since a force vector between the centroid of the fibula and the tibia in the axial plane should not displace the fibula relative to the tibia, a line connecting the two centroids was therefore postulated to be the ideal syndesmosis line, and also the optimum position in which to place a compression clamp after reducing the syndesmosis. Where this ideal line passed through the lateral border of the fibula, and through the medial malleolus was then noted.

The ideal syndesmosis line was shown to pass through the fibula with in 2mm of the lateral cortical apex of the fibula, and the anterior half of the medial malleolus in 100% of the ankles studied. The results support the concept that in the operatively reduced syndesmosis, the anterior half of the medial malleolus can be used as a reliable guide for aiming the syndesmosis drill hole, provided that the fibular entry point is at or adjacent the lateral fibular apex.

The corollary of these findings is that a screw inserted through a plate on the standard antero-lateral border of the fibula, or a plate in the anti-glide position posteriorly, cannot lie in the centroidal axis of the ankle.

Objective

To determine differences in fracture stability and functional outcome between synthetic bone graft and allograft/autograft with internal fixation of tibia plateau metaphyseal defects.