Leg dominance affects the appearance of osteoarthritis of the lumbar facet joints at L5-S.

The influence of leg dominance on lumbar intervertebral joint deformity and osteoarthritis remains poorly understood, particularly across different age groups. A clearer understanding of this relationship could improve rehabilitation strategies and patient outcomes. This study investigated 109 patients with spinal disorders who had not undergone spinal surgery and underwent computed tomography after myelography between May 2023 and January 2024 at our hospital. Lateral lumbar radiographs in a neutral standing position were used to evaluate lumbar lordosis (L1-S), lower lumbar lordosis (L4-S), pelvic incidence, and sacral slope. Hand and leg dominance were self-reported before admission, and observed leg dominance (determined by the leg used to climb onto a platform) was recorded. Lumbar facet joint osteoarthritis at each disk level was assessed using computed tomography imaging. Most participants reported right-side dominance for both the hand (101 participants, 92.7%) and leg (98 participants, 90%). Concordance between hand and leg dominance was observed in 102 (93.6%) participants. The most pronounced difference in osteoarthritis prevalence between the dominant and nondominant-leg sides at L5-S occurred among participants aged 45-64 years. Osteoarthritis on the dominant-leg side developed earlier (after age 40) than on the nondominant-leg side, where it emerged approximately a decade later. These findings suggest that leg dominance plays a role in lumbar facet joint degeneration, underscoring the need for further research and clinical consideration.