Aseptic loosening after CD instrumentation in the treatment of scoliosis: a report about eight cases.

We report eight patients who had had operative treatment of idiopathic scoliosis with CD instrumentation and developed radiolucency around pedicle screws and a discharging sinus. There are two recent reports (Dubousset J, Shuffleberger H, Wenger D. Late infection with CD instrumentation. Orthop Trans 18:121, 1994; Richards BS. Delayed infections following posterior spinal instrumentation for the treatment of idiopathic scoliosis. J Bone Joint Surg [Am] 4:524-529, 1995) describing delayed infection with spontaneous drainage after the treatment of scoliosis with CD instrumentation and Texas Scottish Rite Hospital system with controversial results. Eight patients had radiologic signs of implant loosening after a mean of 7 months, with radiolucency around the pedicle screws. Six patients developed a painful swelling and a discharging sinus after a mean of 21 months. Histopathologic results showed metal wear and chronic inflammatory reaction with granuloma formation. No evidence of pyogenic infection was present. We believe that this complication is caused by micromotion.