Lumbar disc disease: the effect of inversion on clinical symptoms and a comparison of the rate of surgery after inversion therapy with the rate of surgery in neurosurgery controls.

Patients were not randomised to inversion therapy or control groups, so the observed surgery difference may reflect selection. The inversion registry was screened by four of twelve neurosurgeons, while controls came from all twelve, and registry inclusion required a single-level unilateral disc on MRI with surgery indicated. Matched controls were chosen from clinic records by text search, and sometimes only one match could be found instead of two. The waiting-list control group was already on a surgical waiting list and had a 96% surgery rate within 12 months, so it may not represent patients who were not already listed for surgery. Symptom outcomes were self-reported and compared mainly with each patient's own baseline, not with a randomised control group. Not all patients completed outcome questionnaires; 70 of 85 returned an outcome questionnaire at one or both time points. Teeter International Ltd supplied the inversion tables and funded the study administrator.

Teeter International Ltd funded the study administrator and supplied the inversion tables. The authors state that the study's conception, analysis, interpretation, and submission for publication occurred completely independently of this sponsor.

Do not conclude that inversion therapy caused the lower surgery rate. The study was not randomised, controls were selected from clinic records, and the registry was screened by only four of twelve neurosurgeons, so selection and other differences could explain the result.