Late implant infections caused by Propionibacterium acnes in scoliosis surgery

One hundred and one consecutive adolescent scoliosis patients instrumented from the posterior between 1995 and 2002, with a minimum follow-up of 24 months (maximum 106 months), were reviewed for incidence of infection. Stainless steel implants with pedicle screws were used in the thoracic and lumbar spine of all patients. All were operated on by a single surgeon. There were no early infections. Incidence of late infection was 6.9% (seven patients). Clinical indicators for infection were the sudden onset of local pain and swelling without fever after an initial pain-free interval. There were no reliable laboratory parameters. Normal CRP and ESR did not rule out a late infection. Extended cultures were done from intraoperative swabs. Propionibacterium acnes was found in six patients. There were no other organisms identified. No causative organism could be identified in one patient, despite extended cultures. All patients were successfully treated with implant removal and antibiotic therapy for 4-9 weeks. No pseudarthrosis was seen on implant removal. Despite bony fusion, loss of correction between 10 degrees and 26 degrees was observed in three patients after implant removal.