Combination of intramedullary rod, wrapping bone grafting and Ilizarov’s fixator for the treatment of Crawford type IV congenital pseudarthrosis of the tibia: mid-term follow up of 56 cases

Although the outcomes from numerous treatment methods for congenital pseudarthrosis of the tibia had shown greatly improvement in primary union [1, 5], there are still many challenging problems that include potential risks of non-union, re-fractures, leg length discrepancy (LLD), and malalignment of the tibia and the ankle [17]. Currently, there is no consensus on the optimal surgical technique for treatment of congenital pseudarthrosis of the tibia.

Ilizarov technique was widely used to manage with CPT, with the biggest advantage of the tibial fragments being compressed, lengthening of the tibia, and correction of angular deformities concomitantly. The drawback of Ilizarov technique was its lack of protection against re-fractures after removal of the fixator and usually associated with a high re-fracture rate [4, 12]. Inan et al. reported 16 patients treated with Ilizarov, all the patients united but 10 patients had late axial malalignment and re-fracture [17]. Cho et al. reported a rate of re-fracture of 47 % in a series of 23 patients with atrophic CPT treated by Ilizarov’s technique [18].

Intramedullary rod was another commonly method used for treatment of CPT popularized by Umber et al. in 1982 and obtained relative high union rate [5, 19]. An additional benefit of this technique could provide protection against re-fracture before skeletal maturity [1, 20]. Dobbs successfully treated 18 of 21 patients with intramedullary rod but re-fracture occurred in twelve patients [9]. Joseph and Mathew treated 14 patients with congenital pseudarthrosis of the tibia using excision of the pseudarthrosis, double onlay autogenous cortical bone grafting, and intramedullary nailing [21]. Of 14 pseudarthrosis of the tibia, 12 patients achieved union without re-fractures occurred at the site of the original pseudarthrosis. But in practice, we found the onlay cortical bone grafting to be unstable and may be absorbed spontaneously during the fixation. Thus, since February 2007, we used intramedullary rod and wrapping autogenic iliac bone graft in combination with Ilizarov’s fixator for treatment of congenital pseudarthrosis of the tibia and attempted to take advantages of both Ilizarov’s fixator and intramedullary fixation, and avoid the disadvantage of onlay cortical bone grafting. The Ilizarov’s fixator could provide high fusion rate with good alignment control, while intramedullary fixation could stabilize the pseudarthrosis and avoid re-fracture. The wrapping autogenous cortex and cancellous bone grafting would make the grafting and pseudarthrosis close contacted over a large surface area, which may enhance mechanical stability and provide a unique biologic environment promoting union.

In current study, 56 patients with congenital pseudarthrosis of the tibia were treated by the combined procedure and 50 (89.3 %) patients achieved initial union at site of pseudarthrosis at a mean follow-up of 5.2 years, while another 5 case obtained union after second surgery, only 1 failed union. During a 5.2 years follow up (the shortest was 3.5 years), we observed the total refracture rate was 26.0 %. The primary union rate and the refracture rate of ours were comparable to those reported in the literature [8, 21, 22]. However, high frequency of residual deformities including proximal tibial valgus, ankle valgus, LLD and still existed, which is similar to Dobbs and Kristiansen’s study [9, 12].

The incidence of proximal tibial valgus post opreration was 19.6 % with an average of 9.5°, and we observed proximal tibial dysplasia in these patients. Cho et al. pointed that the proximal tibial dysplasia reflects a pathological process of the periosteum same as fibrous hamartoma in the pseudarthrosis site, and the extent of this lesion varies in patients [23]. We surmise that proximal tibial dysplasia may result to unbalanced growth of proximal tibial which seems to be attributable to tibial valgus of our series. Epiphysiodesis by staple or screw fixation can be introduced to correct tibial valgus in these younger patients.

Ten (17.9 %) patients had ankle valgus deformities post operation with a mean of 12.3°, which is similar to other investigators [9, 10]. Some authors reported that persistent fibular pseudarthrosis may relate to progressive ankle valgus [12, 17]. Distal tibia corrective osteotomy, fibular stabilization by temporary hemiepiphysiodesis or tibiofibular synostosis would be advocated if serious ankle valgus deformities were existed.

An average of 2.2 cm LLD in 16/56 case was observed in our series. The LLD following success union may ascribe to the discrepancy of limb length pre-operation and the acute shortening at the time of the pseudarthrosis resection. Either epiphysiodesis of the contralateral side or tibial lengthening of the involved side could be used to equalize the limb length [12, 17]. In our experience, we suggested that proximal tibial lengthening could be considered when the LLD was more than 4 cm in younger children after primary union of CPT [13].

Residual problems such as proximal tibia valgus, ankle valgus, LLD and refracture are common despite successful union of pseudoarthrosis, thus more attention should be paid to these residual deformities and revision surgeries may need to correct these deformities.

The present study has three limitations. First, it was not long enough to document real incidence of residual deformities with this combined approach, including proximal tibial valgus, ankle valgus, LLD, and refracture. It is necessary to follow up these younger patients until skeletal maturity and to evaluate the long term outcome of the combined technique. Second, we need to carry out some well designed prospective studies to investigate the advantage of wrapping autogenic iliac bone graft. Last but not least, due to its retrospective properties, some data were not available to carry out comparative research for this series.