One-footed and externally disturbed two-footed postural control in patients with chronic low back pain and healthy control subjects. A controlled study with follow-up.

STUDY DESIGN: A study of postural control during one-footed and externally disturbed two-footed stance among healthy control subjects and patients with chronic low back pain at the beginning of a functional back restoration program and 6 months later at follow-up examination.

OBJECTIVES: To study postural control cross-sectionally among control subjects and patients with low back pain, and to evaluate the effects of functional restoration on the postural control parameters in a follow-up examination.

SUMMARY OF BACKGROUND DATA: Deficits of motor skills and coordination have been reported in association with musculoskeletal disorders. It has been found that patients with chronic low back pain have impaired psychomotor control, but the impairment is reversible with successful low back rehabilitation. It is insufficiently known how functional activation and intensive physical training affect postural control.

METHODS: Sixty-one healthy volunteers (32 men, 29 women) and altogether 99 patients with low back pain participated in the study. Sixty-eight patients (33 men, 35 women) had moderate and 31 (18 men, 13 women) had severe low back pain. Postural stability was measured with a force platform. In two-footed stance, vibration stimulation on calf and back muscles was used to disturb the balance. Center point of force-velocity (cm/sec), average position shift in anteroposterior direction (cm), and maximal position shift in lateral direction (cm) were used as the parameters.

RESULTS: Reliability of all tests was acceptable. Center point of force-velocity was the most sensitive parameter and the one-footed measurement the most sensitivetest for evaluating postural stability. At the beginning, the patients with severe low back pain had poorer one-footed postural control compared with the control subjects (P = 0.0003). The subgroup of patients with moderate low back pain participated in the restoration program. The outcome of the restoration program was considered good if the disability because of low back pain (Oswestry index) decreased during the restoration program and poor if the disability increased or did not change. The one-footed postural stability remained primarily at the same level as the initial results in the control and good outcome groups, but became significantly poorer in the poor outcome group. The difference between poor outcome and control groups was statistically significant (P = 0.04).

CONCLUSIONS: Impaired postural stability seems to be one factor in multidimensional symptomatology of patients with chronic low back trouble. Postural stability is easily disturbed in case of impairment in strength, coordination, or effective coupling of muscles in the lumbar and pelvic area. Patients with chronic low back pain seem to experience impairment in these functions, which should be taken into consideration when back rehabilitation programs are planned.