Purpose: The study determined the prevalence of subspinal impingement (SSI) in symptomatic and asymptomatic individuals, morphologic characteristics in symptomatic patients, and risk factors for SSI.
Methods: The study cohort consisted of 427 patients (427 hips; median age 33.4 years; range 19-50 years) with mechanical symptoms who underwent multi-detector computed tomography arthrography (symptomatic patients) and 259 control (asymptomatic) patients who underwent abdominopelvic three-dimensional CT because of a ureter stone or minor trauma. Two orthopaedic surgeons reviewed the images to evaluate the prevalence of SSI and the relationship with morphologic abnormalities. Radiologic parameters were further compared between the SSI and non-SSI groups in symptomatic patients using the Chi-squared test or two-sample t test. Variables with p values <0.10 (sex and age) were included in the multi-variate analysis. Logistic regression analysis was carried out to identify independent risk factors for SSI.
Results: The prevalence of SSI in symptomatic and asymptomatic patients was 65/427 (15.2%) and 40/259 (15.4%), respectively (n.s.). Structural bony abnormalities in symptomatic patients were not associated with the presence of SSI (n.s.). Binary logistic regression analysis revealed that youth (odds ratio 0.952, 95% CI 0.922-0.984) was the only significant factor for SSI.
Conclusions: SSI had a similar prevalence in symptomatic and asymptomatic patients and was not rare in either group. Therefore, clinical implication of SSI in symptomatic patient should be re-evaluated through further study.
Level of evidence: Level IV.
Keywords: Extra-articular; Femoroacetabular impingement; Prevalence; Subspinal.