Pelvic fractures after long lumbosacral spine fusions

Study Design. A retrospective review of late pelvic ring fractures after long spine fusions to the lumbosacral spine. Objectives. To review the clinical course and predisposing features of late fractures of the pelvic ring, usually atraumatic, in patients with long fusions to the lumbosacral spine. Summary of Background Data. Fractures of the pelvic ring after long fusions to the lumbosacral spine is a heretofore rarely reported complication. Methods. Records from the authors' institution from 1985 to 1994 were reviewed retrospectively. Two hundred sixty-eight patients with long fusions to the lumbosacrum were identified. Results. Between 1985-1994, five patients suffered late atraumatic fractures of the pelvic ring after long instrumented fusions to L5 or the sacrum. All fractures were on the left side of the pelvic ring, primarily the pubic rami. All patients were women, and at the time of fracture, all were aged 50 years or older. Fractures occurred from 4 months to 7 years after the last surgery (mean, 28 months). All were treated with protected weightbearing until comfortable. At average 27 months' follow-up evaluation, four patients reported no pain; the fifth had become pain-free at 31 months, but 2 months later, the patient spontaneously fractured the contralateral pubic rami. Conclusion. Stress-type fractures of the pelvic ring are a potential source of late pain after long fusions to the lumbosacral spine. Orthopedic surgeons should be aware of this possibility, especially in older, potentially osteoporotic women. Early treatment with simple protected weightbearing appears satisfactory and can prevent significant morbidity.