“4-in-1 Osteosynthesis” for Atrophic-type Congenital Pseudarthrosis of the Tibia

Abstract

According to the authors' multi-targeted, fibular status-based algorithmic approach using the Ilizarov technique, ankle stabilization by end-to-end osteosynthesis of the fibula is advocated for mild (type B1), "4-in-1 osteosynthesis" in which all 4 proximal and distal segments of the tibia and fibula are placed in 1 healing mass for moderate (type B2), and distal tibiofibular (TF) fusion for severe (type B3) fibular pseudarthrosis in association with atrophic-type congenital pseudarthrosis of the tibia (CPT). This report describes the indications, operative technique, and outcomes of "4-in-1 osteosynthesis" for atrophic-type CPT associated with type B2 fibular pseudarthrosis. Thirteen patients presented with atrophic-type CPT associated with type B2 fibular pseudarthrosis underwent Ilizarov osteosynthesis between 1989 and 2007 for atrophic-type CPT. To validate the efficacy of "4-in-1 osteosynthesis" in these patients, fracture risk and ankle function were compared between 2 groups of type B2 patients, namely, 8 patients (mean age, 6.3 y) who underwent "4-in-1 osteosynthesis" according to our current protocol (Group I), and 5 patients (mean age, 3.2 y) treated by other techniques (3 distal TF fusion, 2 failed end-to-end osteosynthesis) during the learning period (Group II). No refracture occurred in Group I, whereas refracture occurred in all except 1 in Group II. Ankles were eventually stabilized by distal TF fusion in all patients in Group II. The Kaplan-Meier method revealed a refracture-free cumulative survival rate of 100% in Group I, whereas in Group II, it dropped progressively and reached 60% at 1.8 years and 20% at 2.7 years. No significant difference in ankle function was evident between the 2 groups (american orthopaedic foot and ankle society (AOFAS) score, 89.25 ± 7.25 after 7.4 y of follow-up in Group I, and 84.6 ± 9.53 after 13 y of follow-up in Group II). It is imperative that fibular status be evaluated carefully to enable the planning of the most effective, safe, practical treatment. "4-in-1 osteosynthesis," which is primarily considered for bony union with a large cross-sectional area and ankle stabilization, seems to be a better choice for atrophic-type CPT associated with type B2 fibular pseudarthrosis, in which end-to-end osteosynthesis of the fibula often fails. Level III, Retrospective comparative study.