Imaging Parameters for Contralateral Hip Dysplasia in Asymptomatic Adults Over 60 Years Old With Femoral Neck Fractures.

objectiveIt is unclear whether a hip with a developmental dysplasia deformity can remain functional and free of osteoarthritis (OA) throughout life. This study aims to determine the percentage of Chinese older adults without severe OA who meet the diagnostic criteria for DDH and BDDH. Additionally, this study seeks to explore hip morphology in this population.

methodsData from 808 consecutive patients with recent unilateral femoral neck fractures, collected between January 2022 and October 2024, were retrospectively analyzed. A total of 493 patients (493 hips) were included in the analysis. For imaging evaluation, the following parameters of the contralateral (unfractured) hip were measured: LCEA, Tönnis angle, Sharp's angle, femoral head eminence index (FHEI), and femoral head lateralization. Categorical variables were expressed as numbers and percentages. Continuous variables were presented as mean ± SD if normally distributed; otherwise, they were reported as median (Q1, Q3). The Pearson chi-square test, likelihood ratio chi-square test, or Fisher's exact test was used to compare categorical variables. An independent-samples t-test or Mann-Whitney U test was used to compare continuous variables in the group analysis. For parameter comparisons between multiple groups, use ANOVA with post hoc analysis.

resultsIn this study, 7.1% of individuals aged over 60 years with unilateral femoral neck fractures exhibited imaging results consistent with DDH, while 13.2% had results consistent with BDDH. Patients with DDH and BDDH were at a higher risk of developing mild OA compared to individuals with normal acetabular coverage. However, not all individuals with DDH or BDDH develop OA. Only the Tönnis angle was significantly associated with mild OA, indicating a 7.8% increase in OA risk for each 1° increase in the Tönnis angle. Significant differences were observed in the Tönnis angle (5.0 ± 3.9 vs. 11.5 ± 4.1 vs. 17.5 ± 4.1, p < 0.001), Sharp's angle (38.2 ± 2.9 vs. 41.7 ± 2.5 vs. 44.0 ± 2.5, p < 0.001), femoral head lateralization (7.8 ± 2.7 vs. 9.3 ± 2.6 vs. 10.3 ± 2.8, p < 0.001), and FHEI (17 ± 4 vs. 25 ± 3 vs. 30 ± 4, p < 0.001) between the normal group and both the DDH and BDDH groups.

conclusionThe prevalence of DDH imaging abnormalities is notable among Chinese older adults without severe OA. Individuals with DDH and BDDH are more likely to exhibit mild OA symptoms, although not all develop OA. Using multiple imaging parameters in addition to LCEA facilitates characterizing hip morphology in asymptomatic individuals with DDH.