Abstract
BACKGROUND: The risk factors for proximal radial abnormalities (PRA) in paediatric patients with untreated chronic Monteggia fractures (CMFs) are unclear. This multicentre study aimed to evaluate the risk factors for PRA in children with untreated CMFs. MATERIALS AND METHODS: The clinical data of 142 patients (mean age at the time of injury: 5.73 years) with untreated unilateral CMFs were retrospectively reviewed. The radial neck-shaft angle (RNS(AP)) and radial head size (RH(L)) were measured on anteroposterior (AP) and lateral (L) radiographs, respectively. The RH(L) size was the ratio of the widest width of the proximal radial metaphysis to the narrowest radial neck width. The En-RNS(AP) and En-RH(L) were the ratios of the enlargement (En) of the RNS(AP) angle and RH(L) size of the injured elbow to those of the uninjured elbow, respectively. Paired-sample t-tests, single-factor analyses and multiple linear regression analyses were performed to evaluate the correlation between the differences in these parameters between the injured and uninjured elbows and the assessed risk factors. These risk factors included institution, sex, laterality, age at injury, time from injury to diagnosis, direction of RH dislocation, distance of RH dislocation (DD-RH), presence of radial or median nerve injury, heterotopic ossification and immobilization of the elbow after injury. RESULTS: In children with untreated CMFs (mean time from injury to diagnosis: 14.6 months), Student's t-test revealed a significant difference in the RH(L) size (P < 0.001) but not in the RNS(AP) angle (P = 0.075) between the injured and uninjured elbows. Pearson correlation analysis revealed a potential correlation between En-RH(L) and age at the time of injury (P = 0.069), time from injury to diagnosis (P < 0.001) and DD-RH (P < 0.001), excluding other risk factors (P > 0.05). Multiple linear regression analysis revealed that age at the time of injury (P = 0.047), time from injury to diagnosis (P = 0.007) and DD-RH (P = 0.001) were risk factors for an increased En-RH(L) in patients with untreated CMFs; the variability in En-RH(L) among the other three risk factors was 21.4%. CONCLUSIONS: In paediatric patients with unilateral untreated CMFs, PRA of the injured elbow consisted mainly of RH enlargement or radial neck narrowing rather than valgus deformities of the proximal radius. Older age at injury, increased time from injury to diagnosis and DD-RH were risk factors for more severe PRA. LEVEL OF EVIDENCE: III.