Combined technique with hydroxyapatite coated intramedullary nails in treatment of anterolateral bowing of congenital pseudarthrosis of tibia

Abstract

Purpose: The goal of this study is to evaluate the treatment outcomes of anterolateral bowing and residual deformities of distal tibia in patients with CPT using circular external fixation and hydroxyapatite coated flexible intramedullary nailing without excision of affected part of tibia.

Patients and methods: Six patients (4 boys and 2 girls, mean age 12.4 ± 4.1 years) were included in the study. Mean follow-up is 2.1 years. In 4 patients with early onset of disease initial surgical treatment (at age of 5-8 years) was dysplastic zone or pseudarthrosis resection with proximal metaphyseal osteotomy for bone transport. Children with unbroken bowed tibia (2 cases of type II according to Crawford classification) had no previous surgery. Neurofibromatosis type I was diagnosed in 4 cases. Surgical technique for residual deformity correction consisted of percutaneous osteotomy, application of circular external frame and composite hydroxyapatite-coated intramedullary nailing.

Results: Mean external fixation time was 95.3 ± 17.5 days. All patients never get fractured after frame removal. At the present time, they are considered to be healed, in 2.1 years, in average, without fractures or deformity recurrence. Mean lower limb length discrepancy varied from 2 to 10 mm at the latest follow-up control. After realignment procedure, patients didn't require additional surgery but one. Intramedullary nails were removed in two years after deformity correction for individual reason.

Conclusion: Correction of anterolateral bowing or residual deformity in children with CPT is indicated. Association of external fixation with intramedullary nailing/rodding left in situ after frame removal ensure stability and accuracy of deformity correction. Biological methods of stimulation of bone formation in dysplastic zone are obligatory to ensure bone union. Intramedullary nailing with composite hydroxyapatite-coated surface provides mechanical and biological advantages in patients with CPT.

Keywords: Flexible intramedullary nailing; Hydroxyapatite; congenital pseudarthrosis of tibia.

Fig. 1

Deformity correction in a 15 y.o. boy, Crawford, type I: a - preoperative photo, characteristic “café-au-lait” spots noted by arrows; b – preoperative X-rays and computer 3-D reconstruction of bowed tibia; c – photo of leg with Taylor Spatial Frame® by the end of correction phase; d – long-standing radiographs of lower limbs by the end of correction phase; e − radiograph of tibia (external fixation and bipolar FIN) demonstrating bone union; f – radiographs of the tibia on the day of frame removal; g - radiographs of the tibia in 6 months after frame removal; h – radiographs of the tibia in 2 years after frame removal, intramedullary nails removed, i - long-standing radiographs of lower limbs in 2 years after frame removal, maintenance of alignment.

Fig. 2

Deformity correction in a 9 y.o. boy, previously operated with Ilizarov technique: a – preoperative radiographs of tibia; b – deformity correction with Ilizarov frame and one flexible intramedullary antegrade nail; c – radiographs of the tibia after frame removal; d – radiographs of both tibias in a years after treatment, maintenance of alignment; e − radiograph and computed tomography (arrows indicate sites of scans) of healthy (right) and operated (left) tibia. Note cortical continuity, cancellous bone formation around intramedullary nail in left tibia.