A study of isokinetic trunk and knee muscle strength in patients with chronic sciatica

Abstract

To evaluate trunk and knee muscle strength in patients with chronic sciatica in order to optimize the program of management in a rehabilitation setting. This is a prospective study which included 68 subjects. The first group (G1) comported 28 patients with right-side chronic sciatica. The second group (G2) comported 40 healthy controls. The strength of both trunk and knee muscles was evaluated by the isokinetic dynamometer. Quadriceps and hamstring muscle strength were evaluated at concentric velocities of 60 and 120°/s and the trunk muscles were evaluated at concentric velocities of 60 and 90°/s. The two groups were comparable. The peak torque values for the trunk flexors were lower in the group G1 ( P < 0.002 and P = 0.01, respectively at 60° and 90°). Similarly, the peak torque values for the trunk extensors was lower in this group ( P < 0.001 and P = 0.001, respectively at angular velocities of 60° and 90°). The deficit was higher in the group of the extensor muscles. The peak torque values for the right quadriceps and hamstrings at angular velocities of 60 and 120°/s were also lower in group G1. The differences were statistically significant ( P < 0.001). In G1, the quadriceps and hamstrings were significantly weaker on the sciatica side than on the unaffected side. The isokinetic muscle strength evaluation allows the therapeut to optimize the management of patients with chronic sciatica. Some studies showed a reduction in both trunk and knee muscle strength in those patients, when compared with healthy subjects. Neurologic reason appears to be unlikely. This deficit may possibly be explained by muscle atrophy secondary to immobilization imposed by chronic pain. Therefore, the therapeutic program should control the pain but also strengthen both the trunk and lower extremity muscles. Some authors say that muscle atrophy mainly affects selective type II muscle fiber, which leads us to propose a strengthening at different contraction speeds especially the faster one (180°/s) to ensure a successful recovery [1] .