Use of hexapod frame to gradually correct congenital and acquired forearm deformity

Abstract

Introduction: Forearm deformity affects patients with Multiple Hereditary Exostosis (MHE), Ollier's disease, and other various congenital deformities as well as those with physeal growth arrest secondary to trauma. Acute correction of such deformities is complicated by risk of neurovascular compromise and as such, techniques that allow for gradual deformity correction are of great interest in this clinical setting. We hypothesized that the use of hexapod frame would allow for reliable correction without neurovascular compromise. Methods: This retrospective, case series reviewed all patients who underwent osteoplasty of the radius and ulna between January 1, 2008, and December 31, 2017, among two surgeons. Patient demographics, comorbidities, radiographic parameters, external fixation index (EFI), and complications were recorded from chart review. Six patients presented with a diagnosis of MHE, two patients with a diagnosis of Ollier's disease, one with short stature homeobox (SHOX) deletion, and one with physeal growth arrest. Results: Of the ten patients identified, the rate of lengthening proceeded between 0.5 and 1 mm/day with an average EFI of 3.7 months/cm for the radius and 7.4 months/cm for the ulna. Average radius and ulna lengthening were 1.5 cm and 2.7 cm, respectively. Average radial bow preoperatively was 1.7 cm with a location of the maximal radial bow at an average of 61% from the radial tuberosity. Radial bow was corrected to 0.6 cm on average with a location of the maximal radial bow at an average of 64%. Neither patients exhibited nerve deficit nor neurapraxia at the conclusion of treatment. One fracture occurred after frame removal, which was treated with open reduction and internal fixation. Conclusion: Hexapod frames can be used to safely correct forearm deformities without neurovascular compromise.