LIMB RECONSTRUCTION ON OSTEOGENESIS IMPERFECTA

Abstract

Increased incidence of complications has been reported when lengthening limbs with underlying bone disorders such as dysplasias and metabolic bone diseases. There is a paucity of literature on limb lengthening in Osteogenesis Imperfecta (OI), probably due to the concern that the bone containing abnormal collagen may not tolerate the external fixators for a long term and there may not be adequate regenerate formation from this abnormal bone.

We performed limb lengthening and deformity correction of nine lower limb long bones in six children with OI. Four children were type I and two were type IV OI as per Sillence classification. The mean age was 14.7 years. All six children had lengthening for femoral shortening and three of them also had lengthening for tibial shortening on the same side. Angular deformities were corrected during lengthening. Five limb segments were treated using a monolateral external fixator and four limb segments were treated using an Ilizarov external fixator. In three children, previously inserted femoral intramedullary nails were left in situ during the course of femoral lengthening. The average lengthening achieved was 6.26 cm. Limb length discrepancies were corrected to within 1.5 cm of the length of the contralateral limb in five children. In one child with fixed pelvic obliquity and spinal scoliosis, functional leg length was achieved. The mean healing index was 33.25 days/cm of lengthening. Among the complications significant ones included, one deep infection, one fracture through the midshaft of the femur, and development of anterior angulation deformity after the removal of the fixator in one tibia. Abnormal bone of OI tolerated the external fixator throughout the period of lengthening without any incidence of migration of wires and screws through the soft bone when distraction forces were applied. The regenerate bone formed within the time that is normally expected in limb lengthening procedures performed for other conditions. We conclude that despite abnormal bone characteristics, limb reconstruction to correct limb length discrepancy and angular deformity can be done safely in children with OI.