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A Novel Classification Method for Developmental Dysplasia of the Hip Based on the Greater Trochanter of the Femur
Mingfeng Li1, Bohan Zhang2, Zheng Cao1
1School of Medicine, Nankai University, Tianjin, People's Republic of China; Senior Department of Orthopedics, The Fourth Medical Center of PLA General Hospital, Beijing, People's Republic of China; National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, People's Republic of China.
Insights
A new classification system for developmental dysplasia of the hip (DDH) accurately identifies femoral neck deformities, improving surgical planning and outcomes. This greater trochanter-based system is more reliable and easier to learn than the traditional Crowe classification.
Area of Science:
- Orthopedic surgery
- Radiology
- Biomedical engineering
Background:
- Developmental dysplasia of the hip (DDH) encompasses a spectrum of hip abnormalities.
- The existing Crowe classification predates the DDH definition and may overlook concurrent femoral neck deformities.
- This limitation can lead to suboptimal surgical planning and outcomes for certain DDH patients.
Purpose of the Study:
- To introduce and validate a novel classification system for DDH based on greater trochanter dislocation height.
- To compare the efficacy of the new system against the traditional Crowe classification in identifying DDH subtypes and guiding treatment.
- To assess the reliability, repeatability, and learning curve of the new classification.
Main Methods:
- Retrospective analysis of 473 DDH patients (574 hips) who underwent total hip arthroplasty between 2016 and 2023.
- Preoperative and postoperative pelvic X-rays were analyzed.
- Data collected included demographics, functional scores, surgical details, and complications.
- Stratified analysis compared the Crowe and new classification systems.
Main Results:
- 16.4% of Crowe I and II DDH patients had concurrent femoral neck shortening deformities, with worse surgical outcomes.
- The new greater trochanter classification accurately identified femoral neck deformities and correlated with surgical difficulty and outcomes.
- The new system demonstrated superior ease of calculation, repeatability, and a lower learning curve compared to the Crowe classification.
Conclusions:
- The proposed greater trochanter classification system effectively distinguishes DDH types and aids in surgical strategy development.
- This anatomically and biomechanically based classification offers a stable and user-friendly alternative to the Crowe classification.
- The new system has the potential to improve surgical planning and patient outcomes in DDH management.
Background:
The change of designation from congenital dysplasia of the hip to developmental dysplasia of the hip (DDH) indicates that the disease spectrum of hip dysplasia has changed. However, the wide-used Crowe classification existed before the DDH definition was proposed. Thus, the Crowe classification does not effectively identify DDH patients who have concurrent femoral neck deformities, resulting in these cases being overlooked.
Methods:
A total of 473 DDH patients (574 hips) who had undergone total hip arthroplasty from January 2016 to September 2023 were recruited into this study. The follow-up time was a mean 30.4 ± 22.0 months. Antero-posterior X-rays of the pelvis were obtained preoperatively, postoperatively, and during follow-up. Data on demographic information, preoperative functional scores, intraoperative information, postoperative functional scores, hospitalization costs, and postoperative complications were collected. Then stratified analysis according to the two classifications separately was performed to evaluate the reliability, repeatability, and popularization cost of the new system.
Results:
In Crowe I and II DDH patients, those who had concomitant femoral neck shortening deformities represented 16.4%, but their intraoperative complications and postoperative functions were significantly worse than traditional Crowe I and II DDH patients. The new classification system based on the dislocation height of the greater trochanter of the femur could accurately identify various types of femoral neck shortening deformities. The subtypes of new classification correlate well with surgical difficulty and clinical outcomes, thereby guiding prosthesis selection and surgical anticipation. Compared to the Crowe classification, the new classification is easier to calculate, exhibits good repeatability, and has a lower learning curve.
Conclusions:
The greater trochanter classification system based on the anatomy and biomechanic could distinguish various types of DDH and aid in making surgical strategies. Furthermore, this new classification is stable and easy to learn compared to the Crowe classification.
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