Abstract
Introduction
Reported advantages of unicompartmental knee replacement (UKR) over total knee replacement (TKR) include better kinematics and less postoperative pain. The reported longevity of UKRs, regardless of design, still does not compare as favourably as that of TKR. Resurfacing-type UKR differ to other UKR in that they result in minimal bone resection.
Objectives
The aim of this study was to review our experience with conversion of a resurfacing UKR prosthesis to a TKR. We sought to determine the causes of failure and compare outcomes in terms of functional scores, range of motion and radiographic measures. We also determined the use of graft and prosthetic revision supplements as well as stemmed implants.
Methods
We retrospectively reviewed the records of 55 patients (Group A), all consecutive, who underwent TKR for a failed UKR from 2003–2008. We chose a cohort of 55 patients (Group B) who had undergone a primary TKR from the same surgeon's database that most closely resembled the study cohort in terms of sex, age and BMI.
Results
The most common mode of failure was base-plate subsidence and progression of disease to other compartments. 55% of patients did not have isolated disease at the time of the initial surgery. Interestingly, 42% who had revision due to progression of disease had mult-icompartmental disease at initial UKR but 19 of 24 patients (79%) who had multi-compartmental disease were revised for other reasons other than progression of disease. 3 (5%) of patients required either tibial and/or femoral augments and/or stems.
Conclusions
Only 5% required complex revision surgery. Thus, a large proportion of conversions of resurfacing UKR to TKR require non-complex surgery with patients having no significant differences in their radiographic measures nor in their clinical measures to those of primary knee replacements.
