Lumbar spinal stenosis with degenerative spondylolisthesis in twins: An observational study from the national Swedish spine registry and the Swedish twin registry.

Background: Only a few studies have investigated the genetic background of lumbar spinal stenosis (LSS) with degenerative spondylolisthesis (DS) requiring surgery. The purpose of this study was to determine the concordance rates for LSS with DS requiring surgery by studying monozygotic (MZ) and dizygotic (DZ) twin pairs.

Methods: Patients between 18 and 85 years of age who underwent surgery for LSS with DS between 1996 and 2022 were identified in the national Swedish spine registry (14,614 patients) and matched with the Swedish Twin Registry to identify MZ and DZ twins. The concordance rates, the MZ/DZ concordance ratios, and the limits of genetic determination were calculated.

Results: We identified 145 twin pairs (27 MZ and 118 DZ pairs) of whom 1 or both twins underwent surgery for LSS with DS. We found no concordant MZ pair and 2 concordant DZ pairs. When we evaluated pairs where at least one twin was operated for LSS with DS we found 2 concordant MZ pairs and 4 concordant DZ pairs (the co-twins were operated for LSS without DS) resulting in the probandwise concordance rate 0.14 (95% CI, 0 to 0.31) for MZ twins and 0.07 (95% CI, 0.02 to 0.13) for DZ twins. The probandwise MZ/DZ concordance ratio was 2.1 (95% CI 0-11.9). The limits of genetic determination were 0.27 to 0.36.

Conclusions: Our findings suggest that heredity may not be of major etiologic importance in most cases of LSS with DS requiring surgery.