Hip-spine syndrome: cross-sectional-study of spinal alignment in patients with coxalgia

Patients presenting with hip diseases often have coexisting spine disorders, a condition that is termed "hip-spine syndrome." However, few reports have evaluated total spinal alignments in patients with coxalgia. In this study, we retrospectively examined the relationship between several clinical and x-ray parameters of the hip joints and spinal alignment in patients with coxalgia.

100 patients with coxalgia (24 men, 76 women; average age, 60.0 years; age range, 16-88 years) were included. We retrospectively evaluated the following clinical and x-ray findings of hip joints and total spinal alignment: range of motion (ROM) and pain score components of the Japanese Orthopaedic Association Hip Score; leg length discrepancy (LLD); osteoarthritis (OA) stage of the hip; spinal coronal balance (Cobb angle and C7-central sacral ventral line [CSVL]); and spinal sagittal balance (sagittal vertical axis [SVA], pelvic tilt (PT), and pelvic incidence [PI]).

Significant positive correlations were detected between C7 - CSVL and LLD ( r = 0.35), whereas a significant negative correlation was found between SVA and hip ROM score ( r = -0.37). A significant positive correlation was also detected between SVA and OA stage of the hip ( r = 0.35).

In the present study, large leg length discrepancy and hip pain may contribute to spinal coronal misalignment. In addition, advanced stage of OA and decreasing ROM of the hip may lead to increased spinal sagittal misalignment. These findings suggest that when evaluating spinal alignment, the progression of OA, LLD, and pain and ROM of the hip joint should be assessed.