The Prevalence of Abnormal Spinopelvic Relationships in Patients Presenting for Primary Total Hip Arthroplasty.

Background: The prevalence of an abnormal spinopelvic relationship in patients presenting for primary total hip arthroplasty (THA) is not well known. The purpose of this study was to identify the prevalence of abnormal spinopelvic relationships in patients presenting for primary THA.

Methods: A retrospective chart review of 338 consecutive, nonselected patients undergoing primary THA from the practice of 2 fellowship-trained adult reconstruction surgeons was performed (J.E.O. and T.S.B.). Sitting and standing radiographs were measured for lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt; the sacral slope was also measured on sitting radiographs (SS). Patients were assessed for the presence of spinopelvic imbalance, defined as PI-LL>10°, and decreased spinopelvic motion, defined as SS-SS< 10°. Descriptive statistics were reported.

Results: A cohort of 338 patients was identified; 110 were excluded. In total, 228 unique patients underwent measurement. One hundred one of 228 patients (44.3%) in the cohort were female. The mean age of the cohort was 60.0 ± 13 years, with the mean body mass index of 31 ± 7 mg/kg. Spinopelvic imbalance (PI-LL > 10°) was present in 142 of 228 patients (62.3%). Decreased motion at the spinopelvic junction (SS-SS < 10°) was present in 78 of 228 patients (34.2%). Fifty (21.9%) patients had both spinopelvic imbalance and decreased spinopelvic motion.

Conclusions: In a cohort of 228 patients presenting for primary THA, the prevalence of spinopelvic imbalance was 62.3%, the prevalence of decreased spinopelvic motion was 34.2%, and the prevalence of both spinopelvic imbalance and decreased spinopelvic motion was 22%. Hip surgeons are likely to encounter patients with abnormal spinopelvic relationships.