Interlocking telescopic rod for patients with osteogenesis imperfecta.

BACKGROUND Intramedullary fixation with use of a telescopic rod with a T-piece is one of the standard methods for long-bone stabilization in growing children with osteogenesis imperfecta. However, installation and removal of this device can cause substantial damage to the distal joint, which limits its use, especially in the tibia. We devised a modification of the telescopic rod system--the interlocking telescopic rod--in which the obturator is a simple rod with a hole, instead of a T-piece, at its distal end. METHODS The clinical and radiographic outcomes were evaluated more than two years following treatment of thirty-two limb segments (twenty-three tibiae and nine femora) with this new rod system in fifteen patients with osteogenesis imperfecta. RESULTS All rods were inserted without an arthrotomy of the distal joint, and all telescoped successfully. The interlocking pin used in the first five limb segments backed out between five and thirty-three months postoperatively. A revised fixation technique was used in the remaining twenty-seven limb segments, and the interlocking pin had not backed out at an average 3.1 years postoperatively. Proximal migration of the obturator was observed in four tibiae after 2.5 years. The cumulative survival rate of the rod at four years postoperatively was 88.7%. CONCLUSIONS Both insertion and removal of an interlocking telescopic rod are much less invasive than insertion and removal of a conventional telescopic rod with a T-piece anchor. The interlocking pin at the distal epiphysis provides effective anchorage for telescoping. Our interim results showed survival of the device to be comparable with, or better than, that of the conventional telescopic rod.