High-force traction did not improve the clinical course of sub-acute and chronic non-specific low back pain

Objective. To determine the efficacy of motorised continuous pelvic traction for nonspecific low back pain of greater than six weeks duration. Design. Randomised, single-blind, placebo-controlled trial with 5, 12 and 26 week follow-up. Setting. The Netherlands. Clinical environment not specified. Patients. One-hundred-and-fifty-one patients with non-specific low back pain of at least six weeks duration were recruited from physiotherapy and general practitioner clinics. Exclusion criteria were a significant improvement in the previous two weeks, evidence of underlying disease processes or previous treatment with lumbar traction. Intervention. All patients received motorised continuous traction in the semi-Fowler's position 12 times in five weeks for 20 minutes per session. All patients were allowed to continue taking the pain medication they had used before entering the study. The 77 patients in the high force traction group received a traction force to the patient's tolerance, with a minimum force of 35 per cent body weight up to a maximum of 50 per cent body weight. In the sham or low force traction group, the pelvic harness was altered so that the traction force caused the harness to tighten around the iliac crests. The traction force was increased until the patient felt a 'little pulling' to a maximum of 20 per cent of body weight. Main outcome measures. The primary outcomes were the patients' global impression of the effect of traction and patient-rated improvement in two problematic activities. Secondary outcome measures were functional status as measured by the Roland Morris disability questionnaire, inclinometric measures of spinal range, severity of the pain as rated by the patient and therapist, disability measured on a visual analogue scale, work absence and additional treatments sought during follow-up. Main results. The intention to treat analysis revealed no significant differences between the groups for any outcome at five, 12 or 26 weeks. A subsequent per protocol analysis produced the same result. Subgroup analyses were performed to determine whether a subgroup of the population benefited from traction. Subgroups were formed based upon age, gender, duration of present episode, symptom radiation below knee, score on General Health Questionnaire, severity of main complaint and appropriateness of traction therapy as judged by treating physiotherapist. In all subgroups there was no significant difference between the traction and sham traction groups. To evaluate whether low force traction had a therapeutic effect, the authors compared the global perceived effect of different traction forces. Global perceived effect did not depend upon the amount of traction force. Conclusion. Continuous motorised high force traction does not improve the clinical course of sub-acute and chronic nonspecific low back pain.