External Fixator Assisted Deformity Correction in Paediatric Patients

Introduction

A paradigm shift has recently been observed in limb reconstruction surgery, with a move away from external fixators where it is possible to achieve the same results using internal fixation. Accuracy with internal fixation is critical as there is no opportunity to adjust correction postoperatively.

Materials and Methods

A review of consecutive external fixator assisted deformity corrections was performed using electronic records and radiographs to analyse preoperative and postoperative lower limb alignment. All patients under 18 treated with this technique were included.

Results

33 segments in 21 patients were corrected between 2012 and 2018 with an average of 3.4 years follow up (1-6.4). 19 of these were tibial and 14 femoral corrections. Multiplanar deformity was corrected in 9 segments. Varus (25 segments) was more common than valgus deformity. The cause of deformity varied with the most frequent causes being trauma, meningococcal infection, longitudinal deficiency, hypophosphataemic rickets and Blount’s disease. Median age at surgery was 15.5 (3-18). A statistically significant improvement was seen between median preoperative and postoperative mechanical axis deviation (preoperative 36mm, postoperative 14mm, p=0.00001). Correction of LDFA and MPTA improved femoral deformity from a median magnitude of 15 to 2 degrees (p=0.001). Tibial deformity improved from a median magnitude of 16 to 2 degrees (p=0.0001). Osteotomies united radiologically at a median of 3.1 months (2-9.7) with one proximal femoral non-union requiring revision surgery. Two deformities corrected at age 7 recurred and required further surgery. There was one common peroneal nerve palsy despite prophylactic neurolysis, two superficial infections and three patients required metalwork removal.

Conclusions

External fixator assisted deformity correction is accurate and allows inexpensive trauma implants to be used to maintain the correction. Preoperative planning, simulation of deformity correction and intraoperative external fixator control allows patients with multilevel, multiplanar deformities to be treated with internal fixation.