Spinopelvic Alignment in Patients With Osteoarthrosis of the Hip

STUDY DESIGN: A retrospective, age- and sex-matched radiographic study. OBJECTIVES: To investigate the spinopelvic alignment in patients with osteoarthosis of the hip (HOA) and those with low back pain (LBP) and to determine the characteristics and differences in both groups. SUMMARY OF BACKGROUND DATA: Hip-spine syndrome, first described by Offierski and MacNab, is quite an important pathology when treating patients with pain in their low back and lower extremities. However, despite it being a well-known entity, few papers have adequately investigated and assessed the spinopelvic alignment in patients with hip-spine syndrome. METHODS: Sagittal and coronal spinopelvic alignments were investigated in 150 patients with HOA and 150 with LBP using radiographs of the whole spine in both anteroposterior and lateral views. Parameters measured in this study were lumbar lordosis (LL), sacral slope (SS), the shift of the sagittal C7 plumb line, pelvic incidence (PI), and pelvic tilt (PT) on the lateral radiographs. On the anteroposterior (AP) films, lumbar scoliosis, pelvic obliquity, leg length discrepancy, the shift of the coronal C7 plumb line, and Sharp angle were measured. These parameters were compared between the two groups. In patients with HOA, the relationships between Sharp angle and other parameters were also analyzed to clarify the possible influence of sagittal and coronal spinopelvic alignments on HOA without acetabular dysplasia. RESULTS: LL, SS, PI, and PO were found to be less in patients with LBP compared with those with HOA, and there was no significant difference in LS between the two groups. PI was significantly greater in HOA patients and strongly correlated to PT, SS, and LL (i.e., as the PI increased so did the PT, SS, and LL). Sharp angles were also significantly greater in HOA patients and strongly correlated to age, LL and SS (i.e., as Sharp angles increased so did LL and SS); however, age decreased in the hip patients. CONCLUSIONS: These findings suggest that higher PI in the younger individual may contribute to the development of HOA in later life without both lumbar kyphosis and acetabular dysplasia because of the anterior uncovering of the acetabulum. More investigation will be expected to analyze the spinopelvic alignment in patients with hip spine syndrome.