Predictors of Radial Head Dislocation in Patients with Multiple Hereditary Exostoses.

Background: Radial head dislocation in patients with multiple hereditary exostoses (MHE) is associated with loss of function and cosmetic problems. The treatment of the deformity with radial head dislocation is difficult and the timing of surgical intervention is important. The aim of this study was to evaluate the factors predictive of radial head dislocation in patients with MHE. Methods: Patients diagnosed with forearm deformity due to MHE between 1995 and 2021 were retrospectively evaluated. Radiographic parameters including radial bow (RB), ulnar bow (UB), total radial bow (TRB), total ulnar bow (TUB), percent ulnar length (PUL), ulnar shortening (US), radial articular angle (RAA), modified Masada classification and irregularity of proximal radioulnar joint (PRUJ) of the dislocated group (group D), that is subluxation or dislocation of the radial head, and the located group (group L) were compared. Results: A total of 18 patients and 25 limbs (5 girls and 13 boys) with a mean age of 10.5 years were included. There were significant differences in TUB (22.8° ± 5.6° vs. 10.7° ± 6.5°), PUL (97.5% ± 5.5% vs. 108.2% ± 7.7%) between group D and group L (p < 0.05). Moreover, irregularity of PRUJ on radiographs was more in group D (p < 0.05). Conclusions: It is possible that appropriate radiographic assessment in relation to radial head dislocation may prevent delayed surgical treatment of forearm deformities in MHE. Level of Evidence: Level IV (Diagnostic).