Initial angular deformity and its recovery of the proximal tibial metaphyseal fracture according to the cause: trampoline-related injury versus other injuries

PURPOSE: This study investigated the initial angular deformity of proximal tibial metaphyseal fracture in children and its recovery during follow-up according to the cause of injury. METHODS: Prospective data about the patients with a proximal tibial metaphyseal fracture at the age less than six years and available follow-up data at two years post-trauma were retrospectively reviewed. They were grouped into trampoline-related injuries (TRI) and non-TRI groups based on the cause of injury. Proximal tibial valgus and recurvatum angles were measured to assess angular deformity on the coronal and sagittal planes, respectively. RESULTS: A total of 47 patients (33 TRI and 14 non-TRI) were included. Initially, the valgus angles were -1.5° in TRI and 1.6° in non-TRI groups (p < 0.001) and the recurvatum angles were 7.8° in TRI and 4.1° in non-TRI groups (p = 0.048). After two-year follow-up, the valgus angles were 0.2° in TRI and 0.9° in non-TRI groups (p = 0.070), and the recurvatum angles were 6.5° in TRI and 2.3° in non-TRI groups (p = 0.001). CONCLUSION: For children with a proximal tibial metaphyseal fracture, the initial coronal deformity was different according to the injury cause (varus in TRI whereas valgus in non-TRI). Although there was a near complete recovery after approximately two years of follow-up in the coronal deformities, the sagittal deformity (genu recurvatum) seems to recover incompletely or tardily, especially for those caused by TRI. LEVEL OF EVIDENCE: III