Implant removal for late-developing infection after instrumented posterior spinal fusion for scoliosis: reinstrumentation reduces loss of correction. A retrospective analysis of 45 cases

A retrospective follow-up study of patients who, having undergone instrumented posterior spinal fusion for scoliosis, experienced late infection and then underwent either implant removal alone or implant removal and instrumented refusion. We conducted this study to determine whether it is possible to avoid loss of correction by a single-stage implant removal and reinstrumentation procedure. There have been a few reports of late-appearing infections after spinal instrumentation. Implant bulk, metallurgic reactions, and contamination with low-virulence microorganisms have been suggested as possible etiologic factors. The clinical symptoms include pain, swelling, redness, and spontaneous drainage of fluid. Complete instrumentation removal and systemic antibiotics is usually curative. We retrospectively reviewed 45 patients who underwent instrumented posterior spinal fusion for scoliosis and experienced development of late infections and, after a mean of 3 years after the initial procedure, either underwent implant removal alone n=35, instrumentation removal (HR) group] or additionally underwent reinstrumentation and fusion n=10, reinstrumentation and fusion (RI&F) group]. Three patients were reinstrumented 1.5 years after instrumentation removal, and seven underwent a one-stage rod removal and reinstrumentation/refusion procedure. Allergic predisposition, protracted postoperative fever, and pseudarthrosis appear to increase the risk of late-developing infection after posterior spinal fusion. All wounds in both groups healed uneventfully. Preoperative radiographic Cobb measurements showed no statistically significant between-group differences. At follow-up, however, outcome was clearly better in the RI&F group: Loss of correction was significantly smaller in reinstrumented patients. Thus, the thoracic Cobb angle was 28±16° (range 0–55°) in the RI&F group versus 42±15° (21–80°) in the HR group, and the lumbar Cobb angle was 22±11° (10–36°) in the RI&F group versus 29±12° (13–54°) in the HR group. The results of our study demonstrate that wound healing is usually uneventful after instrumentation removal for late infection, also when patients undergo instrumented refusion in a one-stage procedure. Reinstrumentation appears to achieve permanent correction of scoliosis.