• Full Name: SUPAKORN KHAJORNCHUMSIN
• Affiliation/Institution: Thammasat University Hospital
• Country: Thailand

Title: CT-Based Assessment of Hip Morphology: Prevalence of Hip Dysplasia in Patients Presenting at Thammasat University Hospital 

Background: Hip dysplasia is a significant risk factor for the development of hip osteoarthritis (OA), involving a spectrum of acetabular and proximal femoral deformities. While early diagnosis is crucial for effective intervention, the prevalence of these morphological variations within the Thai population remains under-reported. 

Objective: To determine the prevalence and classify types of hip dysplasia at Thammasat University Hospital. This study utilized CT scans to evaluate hip morphology, bypassing the positioning artifacts often associated with conventional radiography. 

Methods: We retrospectively reviewed 100 hips from 50 patients (60 male, 40 female; mean age 43.8 ± 14.34 years) using CT images obtained for non-orthopedic indications between January and December 2024. Morphological parameters measured included: lateral center edge angle (LCEA), anterior center edge angle (ACEA), Tonnis angle, anterior acetabular sector angle (AASA), posterior acetabular sector angles (PASA), acetabular version (AV), alpha angle, femoral neck-shaft angle, and anterior femoral head-neck offset. 

Results: The cohort (mean age 43.86 ± 14.34 years) showed mean morphological values of: LCEA 34.39° ± 6.31°, ACEA 58.05° ± 7.24°, Tonnis angle 6.13° ± 5.52°, AASA 65.58° ± 6.47°, PASA 101.5° ± 6.53°, and AV 16.19° ± 4.24°. Clinically, developmental dysplasia (DDH; LCEA <20°) and borderline dysplasia (BHD; LCEA 20–24°) were present in 1% and 5% of hips, respectively. Conversely, acetabular over-coverage was highly prevalent, identified in 98% of hips by ACEA (>45°) and 50% by AASA (>65°). While no cam-type deformities (alpha angle >55°) were observed (0%), 13% of patients exhibited abnormal femoral head-neck offset (<8 mm). 

Conclusion: In conclusion, while hip dysplasia was identified in 6% of the cohort, acetabular over-coverage was remarkably prevalent, affecting 50% based on AASA threshold and 98% on ACEA threshold. Regarding femoral morphology, 13% of the study population exhibited an abnormal femoral head-neck offset, no cam-type deformities were detected, and all patients (100%) exhibited alpha angles within the normal range (<55°).