Joint function and strength in patients before and after knee replacement surgery

Purpose: To evaluate knee joint function and strength before and after total knee replacement. Methods: In a prospective study, 53 patients with osteoarthritis of the knee (10 men, 43 women, average age 64.7 years) were examined directly before and 3 or 5-7 months after total knee replacement surgery. The patients were questioned about pain, and measurements were done to examine gait, mobility, and isokinetic strength. The results for pain, mobility, and walking performance were summarized in a joint score according to Meyers et al. (1989). The results of the isokinetic strength measurements using a dynamometer (Cybex 340) showed large inter-individual differences. Therefore, the results for the operated leg were not compared to a control group, but rather averaged and compared to the non-operated leg (with/without osteoarthritis) using 95% confidence intervals. We measured the maximal isokinetic strength at 60 degrees/sec and strength endurance (work performed at 180 degrees/sec) of the knee extensors and flexors with contralateral comparison. Results: Both the functional measurement variables and the determined strength capabilities showed clear improvements during the investigation period. However, the highly-pronounced preoperative loss of function and strength could not be compensated through rehabilitation in this short treatment time. Particularly the quadriceps muscle, in contrast to the hamstrings, still showed noticeable weakness after rehabilitation. Conclusions: Following conventional rehabilitation, it is necessary to offer reasonably-priced sports therapy to ensure the long-term maintenance of the surgical results (extend knee protheses' functional life, avoid falls and inappropriate mechanical stress on the joint). The concept behind the Tubingen Knee Sport Groups enables patients to gently and lastingly reduce their remaining deficits.