Quantitative measurements of hip abduction strength in lumbar surgery patients

We sought to evaluate the hip abduction strength in patients before and after lumbar surgery.

Eighty-four patients (51 males and 33 females) undergoing surgery for lumbar disc herniation or lumbar canal stenosis were selected. Mean age was 64.7 ± 13.8 years. Seven patients (8.3%) had surgery at multiple levels, including L2-L3 (group A), 27 (32.1%) patients had surgery at multiple levels including L3-L4 (group B), 32 (38.1%) patients had surgery at the L4-L5 level only (group C), and 18 (21.4%) patients had surgery at the L5-S1 level only (group D). Hip abduction strength was measured in the 84 patients preoperatively and in 49 patients postoperatively.

In all patients, preoperative mean hip abduction strength on the symptomatic side and the asymptomatic side was 71.4 ± 34.5 N and 90.7 ± 36.5 N, respectively (p = 0.0008). In groups A and B, there were no significant differences between the mean hip abduction strength on the symptomatic and contralateral side. In group C, those on the symptomatic and contralateral side were 68.0 ± 33.5 N and 89.3 ± 34.8 N, respectively (p = 0.0181). In group D, those on the symptomatic and contralateral side were 74.3 ± 42.4 N and 101.7 ± 44.7 N, respectively (p = 0.0314). In the 49 patients of all groups that could be measured postoperatively, there were no significant differences between the mean hip abduction strength on both sides.

It was confirmed that the gluteus medius, which was main hip abductor, was mainly innervated by L5 and its mean strength significantly improved postoperatively. The possibility of improvement of hip abduction strength, especially with unchanged tibialis anterior strength, could be very useful for operative decisions.