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. 2025 Jan 15;6(1):93-102.
doi: 10.1302/2633-1462.61.BJO-2024-0143.R1.

Association between acetabular coverage over femoral head and rate of joint space narrowing in non-arthritic hips

Toshiyuki Kawai  1 , Kohei Nishitani  1 , Yaichiro Okuzu  1 , Koji Goto  1 , Yutaka Kuroda  1 , Shinichi Kuriyama  1 , Shinichiro Nakamura  1 , Shuichi Matsuda  1
Affiliations

Association between acetabular coverage over femoral head and rate of joint space narrowing in non-arthritic hips

Toshiyuki Kawai et al. Bone Jt Open. .

Abstract

Aims: This study was performed to investigate the association between the acetabular morphology and the joint space narrowing rate (JSNR) in the non-arthritic hip.

Methods: We retrospectively reviewed standing whole-leg radiographs of patients who underwent knee arthroplasty from February 2012 to March 2020 at our institute. Patients with a history of hip surgery, Kellgren-Lawrence grade ≥ II hip osteoarthritis, or rheumatoid arthritis were excluded. The hip JSNR was measured, and the normalized JSNR (nJSNR) was calculated by calibrating the joint space width with the size of the femoral head in 395 patients (790 hips) with a mean age of 73.7 years (SD 8.6). The effects of the lateral centre-edge angle (CEA) and acetabular roof obliquity (ARO) in the standing and supine positions were examined using a multivariate regression model.

Results: The mean JSNR and nJSNR were 0.115 mm/year (SD 0.181) and 2.451 mm/year (SD 3.956), respectively. Multivariate regressions showed that older age was associated with a larger nJSNR (p = 0.010, standardized coefficient (SC) 0.096). The quadratic curve approximation showed that the joint space narrowing was smallest when the CEA was approximately 31.9°. This optimal CEA was the same in the standing and supine positions. Multivariate regressions were separately performed for joints with a CEA of < 31.9° and > 31.9°. When the CEA was < 31.9°, a smaller CEA was associated with a larger nJSNR (p < 0.001, SC 0.282). When the CEA was > 31.9°, a larger CEA was associated with a larger nJSNR (p = 0.012, SC 0.152). The ARO was not associated with the nJSNR.

Conclusion: Both insufficient coverage and over-coverage of the acetabulum over the femoral head were associated with increased joint space narrowing in hips that were non-arthritic at baseline. The effects of insufficient coverage were stronger than those of overcoverage.

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Conflict of interest statement

K. Nishitani reports honararia for lectures from Kyocera, unrelated to this study.

Figures

Fig. 1
Fig. 1
Flowchart showing inclusion and exclusion of patients. BHA, bipolar hemiarthroplasty; RA rheumatoid arthritis; OA, osteoarthritis; THA, total hip arthroplasty.
Fig. 2
Fig. 2
Measurements of the a) centre-edge angle (CEA), b) acetabular roof obliquity (ARO), and hip joint space width (JSW) in a representative case (75-year-old female). c) Anteroposterior (AP) standing whole-leg radiograph taken before surgery. d) AP standing whole-leg radiograph taken five years after surgery. e) Magnified image of the area including the right hip in panel c). f) Magnified image of the area including the right hip in panel d). The JSW and the femoral head diameter were measured as indicated by the yellow lines. JSW1 and JSW2 are the JSWs before surgery and at the final follow-up, respectively. D1 and D2 are the femoral head diameters measured on radiographs at three months after surgery and at the final follow-up, respectively.
Fig. 3
Fig. 3
Association between hip morphology parameters in the standing and supine positions. ARO, acetabular roof obliquity; CEA, centre-edge angle.
Fig. 4
Fig. 4
Association between the centre-edge angle (CEA) and normalized joint space narrowing rate (nJSNR). The curved lines demonstrate the quadratic curve approximation performed to evaluate the association between the CEA in each position and the nJSNR.
Fig. 5
Fig. 5
Relationship between the centre-edge angle (CEA) and normalized joint space narrowing rate (nJSNR). a) Cases with a CEA of < 31.9° in the supine position. b) Cases with a CEA of > 31.9° in the supine position. c) Cases with a CEA of < 31.9° in the standing position. d) Cases with a CEA of > 31.9° in the standing position.
Fig. 6
Fig. 6
Association between acetabular roof obliquity (ARO) and normalized joint space narrowing rate (nJSNR).
Fig. 7
Fig. 7
Box and whisker plots of the centre-edge angle (CEA) groups. Comparison of the normalized joint space narrowing rate (nJSNR) among the three CEA groups. The top and bottom of the boxes indicate the IQR, the line within the box indicates the median, and the whiskers represent points within 1.5 times the width of the IQR.
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