Proximal tibial lengthening by distraction osteogenesis in congenital pseudarthrosis of the tibia

The purposes of this study were to investigate the outcome of distraction osteogenesis (DO) at the proximal tibial metaphysis in congenital pseudarthrosis of the tibia (CPT) patients and to identify the risk factors of poor regenerate bone formation. Twenty-seven cases of DO in 22 patients with CPT, with average age of 7 years, were divided into 2 groups. Group 1 contained those cases in which the target length was achieved with a healing index (HI) of 65 d/cm or less, and group 2 contained those with an HI of more than 65 d/cm and those that received additional procedures to achieve bone healing. Clinical and radiological parameters were analyzed and compared between the 2 groups using the Mann-Whitney U test or Fisher exact test. Ten cases were assigned to group 1, with a mean HI of 39 d/cm, and 17 to group 2 with a mean HI of 117 d/cm. Autogenous bone grafting was additionally performed in 12 cases, bone marrow injection in 4 cases, and demineralized bone matrix insertion in 1 case in group 2. Those cases showing proximal tibial dysplasia on radiograms (11 cases) or that underwent repeated lengthening (6 cases) belonged to group 2. The HI was significantly smaller in cases having neither of these 2 factors as compared with those having any of these factors. The present study shows that proximal tibial lengthening by DO in CPT can be safely performed if the proximal tibia is not dysplastic and has not been lengthened previously and that lengthening at a dysplastic proximal tibial segment or at a previously lengthened segment renders delayed healing and may require additional procedure(s) to promote bone healing. Physeal distraction or DO through subphyseal osteotomy may be justified to gain length in this high-risk group.