Introduction: Pelvic fixation is undertaken in order to restore stability to an unstable pelvis or correct severe scoliotic degeneration of the spine. Instability of the pelvic ring can result from resection of tumours, fractures of the pelvis or infection of the pelvic joints and bones. A number of methods for stabilising the pelvis have been described in the literature including the Galveston Reconstruction (GR)¹ and the triangular frame reconstruction (TFR)². These are associated with an improvement in functional ability, however failure of instrumentation or loosening often occurs.³ A recent mechanical analysis of these techniques has found the technique used in this hospital (GR) performed most poorly.²

Methods: A scoring system was developed from a retrospective analysis of 8 patients. The patients were categorised into two groups (high score and low score) based on age, presence of infection and serious non-associated comorbidities. A patient aged 60 years or over scored 5 points. Patients with bony infection scored 10 points. The presence of serious comorbidity including osteoporosis scored 5 points with minor comorbidities scoring 1 point.

Results: Eight patients who underwent pelvic fixation for varied indications (2 after resection of tumours, 1 fracture, 2 scoliotic degeneration, 3 for infection) were analysed. Three patients had a good functional improvement without loosening of screws beyond 1 year after surgery. These patients were otherwise healthy, relatively young and had no disease processes that affected local bone quality at the site of fixation or serious comorbidities. The other 5 patients all showed evidence of early screw loosening within one year. Of these patients, 2 had a number of serious comorbidities well recognised to compromise bone quality (osteoporosis, long term steroid use) and 3 had pre-existing extensive bony infection.

Discussion: Bone quality of the pelvic bones appears to be the primary predictor of long term functional outcome after pelvic fixation. The 5 patients who had a number of comorbidities well recognised to compromise bone quality all saw early screw loosening within 1 year. Since fixation of the pelvis requires extensive surgery necessitating both posterior and anterior approach and has a number of severe complications such as alteration of urinary, sexual and recto-sigmoid functions the benefit of pelvic fixation should be considered in light of these factors which appear to predict long term outcomes. Further prospective studies of patients undergoing pelvic fixation are required to validate our scoring system.