Aim: To assess patient and surgery related factors to identify any trend leading to a stiff TKR. We also looked at the efficacy of MUA in the treatment of a stiff TKR.

Material and Methods: Retrospective analysis of TKRs which have undergone MUA during the period from 01/01/1999 to 25/06/2005 at Peterborough Hospitals. We included primary TKRs with a minimum post MUA follow-up of six months.

Results: Out of a total of 1809 TKRs, 42 TKRs (2.3%) in 38 patients required MUA. 26 (68%) were females with a median age of 67 years and a median BMI of 30. 34 (81%) had varus knees. Median pre-operative flexion was 100 deg. Median follow-up was 12 months (6 – 45 months). Median pre MUA flexion was 70 deg (15 – 100 deg.). Median surgery to MUA interval was 12 weeks (range: 10 days to 104 wks). Median gain in flexion during MUA was 35 deg (0 – 90 deg). At final follow-up, 74% had lost flexion gained at MUA (median loss: 17.5 deg, mean loss: 20 deg). 71% gained a median of 20 deg flexion with MUA (Mean: 25 deg, range: 15 – 85 deg). Median range of flexion at final follow-up was 90 deg (40 – 120 deg).

Conclusion: We were unable to identify any distinct trends in relation to BMI, pre op flexion, other patient or surgical factors that would help predict occurrence of a stiff TKR. We advocate the use of MUA for a stiff TKR. 71% patients gained 20 to 25 deg flexion with MUA. 74% patients lost about 20 deg flexion gained at MUA. The average post MUA flexion at final follow up was 90 deg. This information is useful when counselling patients undergoing MUA. A protocol for management of stiff TKR is suggested.