[Isokinetic torque of the knee extensor and flexor in patients with recurrent patellar dislocation].

In order to establish the role of muscle strength in the recurrent dislocation of the patella, an isokinetic study was performed using BIODEX, by which the concentric (CC) and passive eccentric (PEC) torques of the quadriceps and hamstrings were measured. The angle velocity was set at 30 degrees and 90 degrees/sec. The subjects were divided into three groups: (I) non-surgical, (II) surgical and (III) normal control. In each group 20 knees were tested, and the following results were obtained. 1. Peak torque: At either 30 degrees/sec or 90 degrees/sec of velocity, it was significantly smaller in group I. On the other hand, the torque in group II was similar to that of group III. 2. E/C (eccentric torque/concentric torque) ratio: PEC was divided by CC to express a muscular strength balance. At 30 degrees/sec velocity, group I showed a significantly high E/C ratio.

CONCLUSIONS

The knees with recurrent dislocation of the patella exhibited significantly lower peak torque and irregular curve patterns. The muscle strength, has been restored to a near-normal level in the surgical group, therefore, the muscle weakness in this disorder can be considered to be a secondary factor. The eccentric torque appeared to play a major role in the development of recurrent dislocation of the patella.