Modular Femoral Stem for Hartofilakidis Type C Hip Dysplasia: Is It Necessary for 1‐mm Increment of Distal Stem Diameter?

ABSTRACT Background S‐ROM prosthesis, one well‐used femoral prosthesis in the patients with developmental dysplasia of the hip (DDH), has a skipping size of the distal stem diameter. The purpose of this study was to investigate whether its 2‐mm incremental diameter could meet clinical needs for high...

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Bibliographic Details
Main Authors: Jiafeng Yi, Hongbin Xie, Yubo Liu, Yijian Huang, Wei Chai, Xiangpeng Kong
Format: Article
Language:English
Published: Wiley 2025-08-01
Series:Orthopaedic Surgery
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Online Access:https://doi.org/10.1111/os.70092
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Summary:ABSTRACT Background S‐ROM prosthesis, one well‐used femoral prosthesis in the patients with developmental dysplasia of the hip (DDH), has a skipping size of the distal stem diameter. The purpose of this study was to investigate whether its 2‐mm incremental diameter could meet clinical needs for high‐riding DDH patients. Methods Between July 2018 and December 2022, the Hartofilakidis type C DDH patients with S‐ROM stem (9 or 11 mm) were retrospectively enrolled according to the inclusion criteria and exclusion criteria in our institute. The intraoperative femur fractures, the diameter of the femoral medullary cavity, the canal filling ratio of the S‐ROM stem, the closure conditions of the stem slot, and the healing rate of subtrochanteric osteotomy were analyzed to evaluate the effect of stem design on clinical outcomes. Statistical analyses were conducted using independent samples t‐tests, chi‐square test, and logistic regression analysis with a significance threshold of p < 0.05. Results A total of 95 patients (109 hips) were included in this study, including 60 hips with 9 mm S‐ROM and 49 hips with 11 mm S‐ROM. Compared with the 9 mm S‐ROM group, the 11 mm S‐ROM group presented nearly 5 times the intraoperative fracture rate (16.3%, 3.3%, p < 0.05). The mean diameter of the femoral medullary cavity in the 9 mm S‐ROM group was 0.84 ± 0.20 mm and in the 11 mm S‐ROM group was 1.03 ± 0.18 mm. The canal filling ratio in the 9 mm S‐ROM group is significantly lower than that of the 11 mm S‐ROM group. In the 11 mm S‐ROM group, the filling ratio of the femoral medullary cavity of fracture hips was significantly higher than that in non‐fracture hips. Conclusion The S‐ROM design with a distal stem diameter increment of every 2 mm would increase the risk of intraoperative periprosthetic femoral fractures in high‐riding DDH patients. It is necessary for a 1‐mm increment of distal stem diameter in such patients. Level of Evidence Level III, retrospective comparative study.
ISSN:1757-7853
1757-7861