The efficacy of traction for lumbar back pain: design of a randomized clinical trial.

Objective: To present the design of a trial on the efficacy of lumbar traction.

Design: Randomized clinical trial.

Patients: Patients with a minimum of 6 wk, nonspecific low back pain.

Intervention: High-dose, motorized, continuous traction with a force between 35% and 50% of the total body weight was compared with sham or low-dose traction with a force between 0 and 20% of body weight. The sham traction was given with a specially developed brace that becomes tighter in the back during traction. This is experienced by patients as if traction were exerted.

Outcome Measures: Primary measures were the patient's global impression of the effect and the severity of three main complaints. Secondary effect measures were functional status, pain, range of motion, work absence and recurrences. The effect measures were rated before randomization and 4 wk, 12 wk and 6 months later.

Conclusion: There have been a number of earlier trials on the efficacy of lumbar traction; they suffer, however, from severe methodological flaws. This trial aimed to avoid these shortcomings.