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

Abstract

Objective To evaluate trunk and knee muscle strength in patients with chronic sciatica. Patients and method Twenty-eight patients with right-side chronic sciatica (group 1, G1) and 40 healthy controls (group 2, G2) were evaluated using an isokinetic dynamometer (Cybex Norm II). 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. Results G1 comprised 15 women and 13 men (mean ± SD age: 34.787 ± 6.06; weight: 65.85 ± 5.33 kg; height: 165 ± 6.92 cm). G2 comprised 20 women and 20 men (mean ± SD age: 35.92 ± 6.66; weight: 67.07 ± 6.12 kg; height: 165.82 ± 7.65 cm. There were no significant inter-group differences concerning these parameters. In G1, the peak torque values for the trunk extensors were 123.71 ± 32.45 and 108.85 ± 32.07 Newton metres (Nm) at angular velocities of 60 and 90°/s, respectively. In G2, the values were 192.73 ± 64.24 and 168.65 ± 53.96 Nm, respectively. In G1, the peak torque values for the trunk flexors were 134.32 ± 30.77 and 124.39 ± 32.59 Nm at angular velocities of 60 and 90°/s, respectively. In G2, they were 177.44 ± 44.1 and 157.81 ± 39.01 Nm, respectively. The difference between G1 and G2 was statistically significant. The peak torque for the right quadriceps in G1 was 100.03 ± 24.45 and 78.71 ± 22.92 Nm at angular velocities of 60 and 120°/s, respectively. In G2, these values were 160.5 ± 36.34 and 131.05 ± 33.42 Nm. The peak torque for the hamstrings in G1 was 56.42 ± 13.02 and 50 ± 13.55 Nm at angular velocities of 60 and 120°/s, respectively. In G2, these values were 97.77 ± 33.32 and 84.72 ± 31.41 Nm. Again the difference between G1 and G2 was statistically significant. We also noted a statistically significant difference between G1 and G2 in terms of the peak quadriceps and hamstring torque values on the left side. In G1, the quadriceps and hamstrings were significantly weaker on the sciatica side than on the unaffected side. Conclusion The present study demonstrated trunk and knee muscle weakness in patients with chronic sciatica, when compared with healthy subjects. This weakness was predominant on the sciatica side. Consequently, the management of these patients should include a knee muscle reinforcement programme.