A reduced range of motion post total knee replacement (TKR) is a recognised problem. Manipulation under anaesthesia (MUA) is commonly performed in the stiff post-operative TKR. Long-term results are variable in the literature. We retrospectively reviewed, prospectively collected data on 48 patients followed up since 1996 from one centre, over an average of 7.5 years, (range 1 to 10 years) and report on the long-term results. During the study period 2.3% of TKRs undelwent MUA. The mean time to MUA post TKR was 12.3 weeks (range 3 to 48). Pre MUA, the mean flexion was 53 degrees. The mean immediate passive flexion post MUA was 97 degrees, an improvement of 44 degrees (Range 10 degrees to 90 degrees, p<0.05). By 1 year, the mean flexion was 87 degrees, an improvement of 34 degrees, (range - degrees 15 to 70 degrees, p < 0.05). At 10 years the mean flexion was 86 degrees, (range 55 degrees to 100 degrees, p<0.05). We found no difference in the gain in range of motion (ROM) between knees manipulated before or after 12 weeks. Additionally, the gain was no different in stiff knees with a pre TKR ROM <90 degrees, compared to a pre TKR ROM >90 degrees. There were no complications as a result of MUA. However, one patient was eventually revised at 2 years secondary to low grade infection. Our findings show that MUA is a safe and effective method at improving the ROM in a stiff post-operative TKR. The improvement is maintained in the long term irrespective of time to MUA and range of motion pre TKR. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.