PHYSICAL PROGRESS AND RESIDUAL IMPAIRMENT QUANTIFICATION AFTER FUNCTIONAL RESTORATION .2. ISOKINETIC TRUNK STRENGTH

The current study evaluated human skeletal muscle performance through isokinetic trunk strength testing before and after a comprehensive functional restoration program for a group of 191 chronic low back pain (CLBP) patients. Four groups of patients were identified: 1) postdiscectomy men (n = 26); 2) unoperated men (n = 90); 3) postdiscectomy women (n = 17); and 4) unoperated women (n = 58). Patient test scores were expressed as work normalized to body weight at 60 and 150-degrees/second. The absolute scores were also expressed as ''percent normal'' relative to a population average normative database (specific to age and gender). An ''effort factor'' based on the average points variance (APV) of computer-generated curves was also calculated. Results demonstrated improvements in trunk strength measures at all speeds in flexion and extension for all groups. All groups also demonstrated a decrease in APV mean scores after functional restoration, with only 1 of 191 patients remaining in the POOR effort (strength inhibited) group after treatment. The postoperative men showed the greatest effort improvement, with APV scores in the ''good'' range increasing from 57% to 91% of the group over the course of treatment. There was virtually no difference in gender-specific trunk strength scores between postdiscectomy and unoperated patients, either at program entry or program discharge. However, compared with the normative database of program completion, even in the presence of good effort, persistent residual (and, possibly, permanent) strength impairment was identified. This residual impairment, which is worse in extension than flexion, worse for women than men, and worse at high speeds versus low speeds, documents residual strength impairment at the administrative end-point of maximum medical improvement (i.e., medical stability, permanent and stationary). The results of this study provide the clinician with a valuable trunk strength data guide with which to gauge the human performance changes expected during and after spinal functional restoration in CLBP-disabled workers.