A prospective study of the interrelationship between subjective and objective measures of disability before and 2 months after lumbar decompression surgery for disc herniation

The value of range of motion (ROM) as an indicator of impairment associated with spinal problems, and in monitoring changes in response to treatment, is a controversial issue. The aim of this study was to examine the interrelationship between subjective disability (Roland-Morris scores) and objectively measured impairment (ROM), both before and in response to spinal decompression surgery, in an older group of patients with herniated lumbar disc (DH). Seventy-six individuals took part in the study: 33 patients (mean age 57 years, SD 9 years) presenting with DH and for whom decompression surgery was planned, and 43 controls (mean age 57 years, SD 7 years), with no history of back pain requiring medical treatment. In the patient group, pain intensity (leg and back; visual analog score), self-rated disability (Roland-Morris score), certain psychological attributes, and ROM of the spine (Spinal Mouse) were measured before and 2 months after decompression surgery. In addition, the patients rated the success of surgery on a 1–5 Likert scale. The pain-free control group performed only the tests of spinal mobility. Before surgery, compared with matched controls, significantly lower values were observed in the DH patients for standing lumbar lordosis (p=0.01), and for range of flexion of the lumbar spine (ROF_lumbar) (p=0.0006), but not of the hips (ROF_hip) (p=0.14). Roland-Morris Disability scores correlated significantly with ROF_lumbar (r=0.61, p=0.0002), but less well with ROF_hip(r=0.43, p=0.01). Two months after surgery, there were significant reductions in back pain and leg pain (p=0.0001) and in Roland-Morris Disability scores (p=0.019). There was also a significant decrease in the group mean values for lumbar lordosis angle (i.e., a “flatter” spine after surgery, p=0.002) and ROF_lumbar (p=0.038). ROF_hip showed a (nonsignificant) tendency to increase (p=0.08) towards normal control values. As a result of these two opposing changes, the range of total trunk flexion showed no significant changes from pre-surgery to 2 months post-surgery (p=0.60). On an individual basis, there was a highly significant relationship between the change in self-rated disability scores and the change in ROF_lumbar, pre-surgery- to 2 months post-surgery (r= −0.82; p<0.0001). Changes in ROF_hip showed no such relationship (r= −0.30, p=0.10). The patients in the “poor” outcome group (“surgery didn’t help”; 9%) had a significantly greater reduction in ROF_lumbar post-surgery compared with the “good” outcome group (“surgery helped”; 91%) (p=0.04). In stepwise linear regression, the change in ROF_lumbar was the only variable accounting for the change in self-rated disability pre-surgery to post-surgery (variables not included: pain intensity, psychological factors). The pivotal role of lumbar mobility in explaining disability emphasizes the importance of measuring lumbar and hip ranges of motion separately, as opposed to “global trunk motion.” In the patient group examined, the determination of lumbar spinal mobility provides a valid, objective measure of function, that shows differences from normal matched controls, that correlates well with self-rated disability, and the changes in which correlate extremely well with subjective changes in disability following surgery.