Correction of Adolescent Tibia Vara by Ilizarov External Fixator

Abstract
Background: Tibia vara, also termed as blount disease. Blount described a group of children who had an onset of varus deformity of the proximal part of the tibia in later childhood or adolescence, a condition that he described as adolescent tibia vara. It is characterized by proximal varus angulation of the tibia associated with medial metaphyseal depression, internal torsion of the tibia and genu recurvatum, growth retardation, and a propensity toward additional pro-gression.
The Ilizarov external fixation and principles provides gradual correction of the angulation, rotation, translation, and length discrepancy, thus minimizing complications.
Aim of Study: The purpose of the current study is to evaluate the results of management of adolescent tibia vara using Ilizarov external fixator.
The morphological outcome will be evaluated radiologi-cally to determine the amount of correction using different angles, axes and complications.
Patients and Methods: Ten were treated lower limbs of 7 patients with tibia vara were treated with application of Ilizarov External Fixator (IEF), between 2014 and 2017 at Ilizarov Unit, Assiut University Hospital. Their mean age was 14 years (range 11-16.8 years). Three patients were males and four patients were females. The right side was affected in one case and the left side in 3 and bilateral in 3. Their main complaint was pain on walking and cosmoses. The patients were subjected to clinical assessment, including local exam-ination as analysis of gait including lateral thrust of the knee and intoeing was done. Followed by AP radiological exami-nation of both lower limbs in standing position for the involved limb. CT scanogram was done for lower limb discrepancy. The residual deformity was reported in 3 extremities. They were above 10 years old, obese, with past history of pervious failed trials for correction. They presented also with decreased knee range of motion. They still satisfied till last follow-up. The varus deformity was associated with shortening in 4 cases with 7 lower limb deformities had shortening ranged from 3- 5cm with mean 4cm, the shortening was corrected with residual limb length difference (±5mm), with procurvatum in 6 cases, with recurvatum in 3 cases and with internal rotation in all patients except one. Ilizarov external fixator was applied and gradual correction was performed. Varus tibiofemoral angle, procurvatum, recurvatum, lower limb discrepancy, internal tibia1 torsion and knee range of motion were measured pre-operatively; post-operatively and at last follow-up.
Results: The mean time for deformity correction and Ilizarov stabilization was 14 weeks (range 12-30 weeks), including 2 weeks of dynamization. The mean deformity of 27.6º varus (range, 19.2º-35.9º) was corrected to 2.8º valgus (range 3º-7.51º) and 22.2º internal rotation (range 0º-49º) was corrected 3º extenal rotation (range 0º-8º), the mean 7.2º procurvatum angle (range 0º-25º) was (range 0º-7º) and 12.4º recurvatum angle (range, 0º-28º) was changed to 3.5°  (range, 15º recurvatum-6º procurvatum). The mean knee range of motion was 126.55º (range 95º-148º), became 129.2º (range, 85º-145º). The mean shortening of 4.5cm (range 3.5-5.5cm) the shortening had been corrected with residual limb length difference (±5mm) in all patients. Construct modification had to be done in 8 cases without anaesthia, and other additional procedures were done to treat complications of the frame in the same operation time.
Wire site inflammation was common and pin tract infection was common and pin tract infection was treated in 8 cases using oral or parentral antibiotics. However there was a case of deep infection that needs debridement. We reported residual deformity in 3 patients, although they were satisfied. There were no neurovascular complications, delayed union or non unions.
Conclusion: Gradual correction of severe adolescent tibia vara by Ilizarov external fixator is economic, effective, accurate and safe. Limitation of the study is short term follow-up and relatively small sample size.