The effect of prior lumbar surgeries on the flexion relaxation phenomenon and its responsiveness to rehabilitative treatment.

BACKGROUND CONTEXT

Abnormal pretreatment flexion-relaxation in chronic disabling occupational lumbar spinal disorder patients has been shown to improve with functional restoration rehabilitation. Little is known about the effects of prior lumbar surgeries on flexion-relaxation and its responsiveness to treatment.

PURPOSE

To quantify the effect of prior lumbar surgeries on the flexion-relaxation phenomenon and its responsiveness to rehabilitative treatment.

STUDY DESIGN/SETTING: A prospective cohort study of chronic disabling occupational lumbar spinal disorder patients, including those with and without prior lumbar spinal surgeries.

PATIENT SAMPLE

A sample of 126 chronic disabling occupational lumbar spinal disorder patients with prior work-related injuries entered an interdisciplinary functional restoration program and agreed to enroll in this study. Fifty-seven patients had undergone surgical decompression or discectomy (n=32) or lumbar fusion (n=25), and the rest had no history of prior injury-related spine surgery (n=69). At post-treatment, 116 patients were reevaluated, including those with prior decompressions or discectomies (n=30), lumbar fusions (n=21), and no surgery (n=65). A comparison group of 30 pain-free control subjects was tested with an identical assessment protocol, and compared with post-rehabilitation outcomes.

OUTCOME MEASURES

Mean surface electromyography (SEMG) at maximum voluntary flexion; subject achievement of flexion-relaxation (SEMG≤3.5 μV); gross lumbar, true lumbar, and pelvic flexion ROM; and a pain visual analog scale self-report during forward bending task. Identical measures were obtained at pretreatment and post-treatment.

METHODS

Patients entered an interdisciplinary functional restoration program, including a quantitatively directed, medically supervised exercise process and a multimodal psychosocial disability management component. The functional restoration program was accompanied by a SEMG-assisted stretching training program, designed to teach relaxation of the lumbar musculature during end-range flexion, thereby improving or normalizing flexion-relaxation and increasing lumbar flexion ROM. At 1 year after discharge from the program, a structured interview was used to obtain socioeconomic outcomes.

RESULTS

At pre-rehabilitation, the no surgery group patients demonstrated significantly better performance than both surgery groups on absolute SEMG at maximum voluntary flexion and on true lumbar flexion ROM. Both surgery groups were less likely to achieve flexion-relaxation than the no surgery patients. The fusion patients had reduced gross lumbar flexion ROM and greater pain during bending compared with the no surgery patients, and reduced true lumbar flexion ROM compared with the discectomy patients. At post-rehabilitation, all groups improved substantially on all measures. When post-rehabilitation measures were compared with the pain-free control group, with gross and true lumbar ROM corrected by 8° per spinal segment fused, there were no differences between any of the patient groups and the pain-free control subjects on spinal ROM and only small differences in SEMG. The three groups had comparable socioeconomic outcomes at 1 year post-treatment in work retention, health-care utilization, new injury, and new surgery.

CONCLUSIONS

Despite the fact that the patients with prior surgery demonstrated greater pretreatment SEMG and ROM deficits, functional restoration treatment, combined with SEMG-assisted stretching training, was successful in improving all these measures by post-treatment. After treatment, both groups demonstrated ROM within anticipated limits, and the majority of patients in all three groups successfully achieved flexion-relaxation. In a chronic disabling occupational lumbar spinal disorder cohort, surgery patients were nearly equal to nonoperated patients in responding to interdisciplinary functional restoration rehabilitation on measures investigated in this study, achieving close to normal performance measures associated with pain-free controls. The responsiveness and final scores shown in this study suggests that flexion-relaxation may be a useful, objective diagnostic tool to measure changes in physical capacity for chronic disabling occupational lumbar spinal disorder patients.