Body motion during repetitive isodynamic lifting: a comparative study of normal subjects and low-back pain patients.

To quantify performance differences between patients with low-back pain (LBP) and a control group during their performance of a repetitive isodynamic lifting task. Case-control study was done. LBP patients were recruited and tested at an outpatient ambulatory chronic pain rehabilitation program before treatment was begun. Fifty-three LBP patients who had prolonged back pain and 53 age and gender matched pain-free control subjects. Overall lifting performance measures included weight lifting and number of lifts completed; kinematic measures of hip and knee movements during lifting were described by hyperbolic tangent models, and included static measures of starting and ending angles, and dynamic measures of midpoint, falltime, and lift speed. Control subjects completed significantly more lifts and lifted more weight than patients. Starting hip flexion was greater for controls and starting knee flexion was greater for patients, indicating that patients used more of a leg lift. Patients and controls also differed significantly on dynamic measures, particularly lifting speed and hip and knee temporal midpoints. Major static and dynamic motion differences were found between LBP patients and controls as they performed repetitive lifting under a constant load. These findings indicate that body motion parameters, in addition to more common strength and endurance measures, are necessary to describe the impact of persistent LBP on a person's lifting abilities.

Differential treatment responses of TMD patients as a function of psychological characteristics.

A number of studies have reported that psychological factors play a significant role in TMD. Several studies have identified subgroups of patients based on their responses to psychological assessments; however, none of these studies have reported on the clinical utility of classifications of TMD patients on these various measures. In this study, the differential response of 133 TMD patients classified within 3 psychosocial-behaviorally based subgroups to a conservative, standardized treatment was examined. The treatment consisted of the combination of an intra-oral appliance, biofeedback, and stress management. Follow-up assessments were conducted 6 months after treatment termination. The results demonstrated that overall as a group patients significantly improved and maintained improvements on physical, psychosocial, and behavioral measures (P < 0.0001). Comparisons across patient subgroups, however, revealed differential patterns of improvement on the outcome measures. Most notably, reliable change indices demonstrated that the patients classified into a subgroup characterized by the greatest degree of psychological distress (Dysfunctional) demonstrated significantly greater improvements on measures of pain intensity (P < 0.001), perceived impact of TMD symptoms on their lives (P < 0.001), depression (P < 0.01), and negative thoughts (P < 0.001), compared with groups characterized by greater interpersonal problems (Interpersonally Distressed) and those patients who appeared to be the least disabled by TMD (Adaptive Copers). These data provide support for the clinical utility of a psychosocial-behavioral classification system and suggest that in future research individualizing treatments and outcome measures based on patient characteristics may improve treatment efficacy and outcome evaluation.