Correction of Rigid Equinovarus Deformity Using a Multiplanar External Fixator

Abstract

Background: The rigid equinovarus foot deformity is a challenging condition treated by the orthopaedic foot and ankle surgeon. Rapid surgical correction of the deformity may lead to skin and neurologic complications. Gradual correction of the deformity with a multiplanar external fixator may decrease these complications. The purpose of this study was to present the results of a group of patients with rigid equinovarus deformities corrected using a multiplanar external fixator. Materials and Methods: We retrospectively reviewed the results of correction of a rigid equinovarus deformity using multiplanar external fixation in a small group of patients. All patients underwent open Achilles lengthening, posterior capsule release, tibialis posterior tendon lengthening, flexor digitorum longus and flexor hallux longus lengthening, followed by application of a multi-planar external fixator with gradual correction of the deformity over a period of several weeks. Preoperative and postoperative deformity and AOFAS ankle-hindfoot scores were assessed. Results: A total of eight rigid equinovarus deformities in six patients were treated with a multiplanar external fixator. The average patient age at the time of surgery was 37.2 (range, 17 to 59 ± 15.0) years. Causes of the deformity included trauma in three patients, traumatic brain injury in two patients, and long-standing rheumatoid arthritis in one patient. The average preoperative AOFAS ankle-hindfoot score was 28.3 (range, 12 to 38 ± 7.7). The average postoperative AOFAS ankle-hindfoot score was 68.1 (range 38 to 86 ± 15.5) at an average followup of 71.9 (30 to 120 ± 36.2) weeks. All deformities were gradually corrected to a plantigrade foot using a multiplanar external fixator over an average time of 5 (range, 4 to 6 ± 0.8) weeks. After correction of the deformity, the external fixator was left in place for a time period equal to or twice the length of time it took to achieve correction. The average duration of external fixation was 10.8 (range, 8 to 16 ± 2.8) weeks. Seven of eight deformities maintained correction at final followup. There was one case of recurrence. Conclusion: Correction of a rigid equinovarus deformity using a multiplanar external fixator was a viable treatment option. It allowed for correction of the deformity in a controlled manner, helping to reduce the risk of neurovascular complications that may result from single stage surgical correction. The risk of wound complications still exists with the correction of such a complex deformity. Level of Evidence: IV, Retrospective Case Series