To evaluate the results of Thompson quadricepsplasty in ankylosis of the knee joint by a comparison of the patients'ages, the causes, the duration of the ankylosis and the preoperative range of motion (ROM).

We reviewed 17 patients who received Thompson quadricepsplasty for knee ankylosis between 1991 and 1998, and who could be followed up for more than one year. We compared the results according to the patients'ages, the causes and degree of ankylosis and the duration. Since onset, the postoperative ROM, the final degree of the flexion, the flexion gain (difference between the preoperative and the postoperative ROM), and the loss of ROM (difference between the intraoperative ROM and the postoperative ROM) were also assessed.

The preoperative mean arc of motion (26.2degrees, range 0degrees-80degrees) and the mean flexion (30degrees, range 5degrees-90degrees) were significantly increased up to a mean of 98.8degrees (75-100degrees) and 102.1degrees (80-130degrees) respectively. In the severe ankylosis group, the flexion gain was significantly increased. However, the correlation according to the patients'ages, causes and duration of the ankylosis were not statistically significant. The mean loss of ROM was 14.7degrees (-20-30degrees), and it occurred within the postoperative 2 month period in most patients.

The Thompson quadricepsplasty procedure can be considered to be an acceptable technique for the treatment of ankylosis of the knee joint. Rehabilitation in the postoperative 2 month period is very important for a good outcome.