Journal of Pediatric Orthopaedics - 2026-05-04 - Journal Article
Predicting Radial Head Dislocation in Hereditary Multiple Osteochondromatosis: A Quantitative Radiologic Approach.
Kurt A, Doğan B, Kavasoğlu M, Canigüroğlu O, Büyük M, Aycan OE
Topics
Key Takeaway
In 186 HMO forearms, a proportional ulnar length (PUL) threshold of ≤0.89 predicted radial head dislocation with 36% overall prevalence, forming the basis of a new 3-tier risk classification.
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Summary
This study sought quantitative radiographic predictors of radial head dislocation (RHD) in HMO to replace descriptive classification systems with limited reliability. Retrospective review of 186 forearms evaluated PUL, radial bowing, ulnar variance, distal radial epiphyseal angle, carpal slip, and lesion distribution via multivariate analysis. PUL ≤0.89 and absence of a distal radius lesion were the only independent predictors of RHD; radial bowing and ulnar variance were not, yielding a 3-tier classification (A1, A2, B).
Key Limitation
The PUL threshold of ≤0.89 was derived and applied within the same retrospective cohort without external validation, limiting generalizability of the cutoff across different patient populations and imaging protocols.
Original Abstract
BACKGROUND
Forearm deformities are common in children with hereditary multiple osteochondromatosis (HMO) and may progress during growth, leading to functional impairment. Among these deformities, radial head dislocation (RHD) represents one of the most clinically significant and potentially preventable complications. Existing classification systems are primarily descriptive and show limited reliability in guiding surveillance and treatment decisions. This study aimed to identify radiologic predictors of RHD in HMO and to develop a quantitative, clinically applicable classification system to support risk stratification during skeletal growth.
METHODS
A retrospective review was conducted of 143 patients (186 forearms) with HMO treated and followed between 2006 and 2024. Standard anteroposterior and lateral radiographs available at the time of evaluation were evaluated for lesion distribution, proportional ulnar length (PUL), radial bowing, ulnar variance, distal radial epiphyseal angle, carpal slip, and the presence of RHD. Forearms were classified using the Masada and Jo systems. Multivariate analysis was performed to identify independent predictors of RHD and to construct a risk-based classification framework.
RESULTS
Radial head dislocation was identified in 36% of forearms. Patients with RHD demonstrated substantially lower PUL compared with those without dislocation, and a PUL threshold of ≤0.89 effectively distinguished high risk from low-risk cases. Absence of a distal radius lesion was also associated with an increased likelihood of RHD, whereas radial bowing and ulnar variance were not independent predictors. Existing classification systems showed limited applicability, with a considerable proportion of forearms remaining unclassifiable. On the basis of radiologic and statistical findings, a 3-tier risk classification was developed: type A1 (PUL ≤0.89 without distal radius lesion), type A2 (PUL ≤0.89 with distal radius lesion), and type B (PUL >0.89).
CONCLUSION
Proportional ulnar length is the most reliable radiographic predictor of radial head dislocation in children with HMO. Incorporating distal radius lesion status improves risk stratification and enables a practical, growth-oriented framework for surveillance and surgical decision-making in pediatric patients. This study presents one of the largest single-center HMO cohorts to propose a reproducible risk stratification system that addresses unclassifiable cases in Masada/Jo criteria and integrates distal radius lesions as a novel modifier.
LEVEL OF EVIDENCE
Level III.