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Abstract

Background:

To report the association between os acetabuli and relevant radiologic measurements in a series of surgically treated hip preservation patients.

Methods:

We retrospectively reviewed 654 hips who underwent preservation surgery between 2012 and 2019, identifying 50 cases with os acetabuli (7.64%). We included 300 hips (277 patients) with radiographs and CT-scans obtained during preoperative assessment, after which the cohort was divided into two groups (with and without os acetabuli). Mean age of the study population was 35 (interquartile range [IQR] 28–42) years old, with 192 (62%) being males. 2 observers measured demographic and radiologic variables. A mixed-effects logistic regression tested the ability of radiologic measurements to predict the presence of os acetabuli.

Results:

No between-group differences were found in terms of sex (156/250 vs. 36/50 males, p = 0.197), alpha angle (64 ± 13° vs. 65 ± 14°, p = 0.372), Tönnis angle (8 ± 7° vs. 7 ± 7°, p = 0.152), neck-shaft angle (132 ± 6° vs. 131 ± 5°, p = 0.199) and CT-acetabular version (16 ± 7° vs. 15 ± 6°, p = 0.221). Significant differences were found in terms of age (34 ± 9 vs. 39 ± 7 years, p = 0.002), lateral centre-edge angle (LCEA) (31 ± 9° vs. 34 ± 7°, p = 0.045), anterior wall index (AWI) (0.45 [IQR 0.37–0.54] vs 0.5 [IQR 0.39–0.6], p = 0.046), CT-femoral version (17 ± 5° vs. 8 ± 4°, p < 0.001), cross-over sign (96/250 vs. 28/50, p = 0.032) and baseline diagnosis (184/250 vs. 44/50 FAIs, p = 0.043), with the os acetabuli-group being older, with more FAI diagnosis/cross-over sign, and with higher LCEA, higher AWI, and a lower femoral version. After adjusting for confounders, only CT-femoral version (odds ratio 0.32; 95% CI. 0.14–0.73, p < 0.007) was associated with presence of os acetabuli.

Conclusions:

Presence of acetabular rim fragments was significantly associated with a lower femoral version. Above 20° of femoral version, the likelihood of os acetabuli was almost zero. Treatment of os acetabuli (i.e., fixation vs. removal) should be adjusted for the underlying diagnosis.

Keywords

Femoroacetabular impingement femoral torsion hip arthroscopy os acetabuli

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Os acetabuli is an indirect radiographic sign of femoral retroversion

Abstract

Background:

Methods:

Results:

Conclusions:

Keywords

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References