Internal lumbar disc derangement with instability catch from monosegmental discopathy. The forgotten mechanical and kinetic surgical back pain syndrome

•The results of spine fusion for “nonspecific” low back pain are inconsistent.•Internal Lumbar Disc derangement with Instability Catch or “ILDDIC” is a definable subgroup of these patients.•Thirty such cases were identified. An outcomes survey was mailed to all these patients and the results reviewed.•Twenty-four (80%) of patients responded at a mean of 30 months and confirmed uniformly good benefit. Clinical records of the six survey non-responders found good report in five of the six.•ILDDIC may represent a subgroup of the back pain population uniquely suited to benefit from interbody fusion surgery.