Comparative study of the strength of the flexor and extensor muscles of the knee through isokinetic evaluation in normal subjects and patients subjected to trans-tibial amputation

This study compares the strength of the flexor and extensor muscles of the knee in a group (A) of 25 patients with unilateral trans-tibial amputation, regardless of cause, and a group (B) of 27 normal volunteers. Measured parameters were peak bending moment, total work, maximum power and flexor/extensor relation. The dynamometer used was a Cybex(R) model 6000, set at velocities of 60degrees/s and 180degrees/s (4 and 20 repetitions). Exercise type was concentric, both for flexion and extension of the knee joint. Patients were grouped according to stump size, age and time since amputation. These patients were tested with their prosthesis. Mean age in group A was 35.9 +/- 13 years (age range: 12-59 years). Mean age in group B was 34 +/- 8 years (age range: 19-56 years). Comparison according to subject sex was similar. Data analysis between the amputated and the sound limb reveals strength deficit (bigger deficit at 180degrees/s), which relates to age but not to stump size. When compared to non-amputated subjects in the measured parameters, negative relations both in the amputated side and the non-amputated side were found. The authors' conclusion is that revision of the parameters used until then for rehabilitation of the patients subjected to trans-tibial amputation is needed.