Hip-Spine Syndrome: Is There an Association Between Markers for Cam Deformity and Osteoarthritis of the Lumbar Spine?

Purpose: To examine a large osteological collection to assess the relations between the well-described means of quantifying cam deformities of the proximal femur-alpha angle (AA) and anterior femoral neck offset (AFNO)-and osteoarthritis of the lumbar spine.

Methods: AA and AFNO were measured on paired femurs of 550 well-preserved cadaveric skeletons by use of standardized cephalocaudal digital photographs. Degenerative disease of these specimens' lumbar spines was graded from 0 to 4 with a validated grading system. Proximal femurs showing obvious arthritic changes such as lipping or osteophytes were excluded. Correlations between AA and spine osteoarthritis (SOA), as well as between AFNO and SOA, were evaluated by multiple regression analysis.

Results: The average age for the skeletons was 47.8 ± 16.2 years. There were 456 male and 94 female specimens. The mean AA and AFNO were 52.4° ± 11.4° and 6.8 ± 1.5 mm, respectively. The average SOA score was 2.1 ± 0.9 (0 in 31 specimens, 1 in 82, 2 in 287, 3 in 106, and 4 in 44). There was a significant correlation between increasing AA and SOA (standardized β = 0.061, P = .041). There was also a significant correlation between decreasing AFNO and SOA (standardized β = -0.067, P = .025). There was a strong correlation between age and SOA (standardized β = 0.582, P < .0005).

Conclusions: This study provides important insight into the understanding of the hip-spine connection. Although it has no way of showing a causative or clinically significant relation, this study did show that the cam-type deformity markers of increasing AA and decreasing AFNO were significantly associated with SOA in a large osteological collection.

Clinical Relevance: Clinical and biomechanical studies to assess whether cam deformity in the younger individual may contribute to the accelerated development of SOA in later life are warranted.