A feasibility study of pelvic morphology for curved implants.

OBJECTIVES: We hypothesize that inserting a curved intramedullary internal fixation device which follows curved osseous fixation paths (OFPs) would be more versatile and mechanically stronger than straight screws for fixation of pelvic ring and acetabular injuries. This study characterizes the dimensions of curved OFPs of the pelvic ring and acetabulum and suggests design parameters for such a curved device. METHODS: CT scans of intact pelves of 50 female and 50 male subjects were studied using MIM Maestro™ and Solidworks™ to determine the constriction points (smallest cross sections) and the tightest radii of curvature (RoC) in the anterior column, posterior column, iliosacral and pubic symphysis OFPs. RESULTS: The constriction point diameters for the superior pubic ramus and supra-acetabular areas were 13±3mm and 12±3mm, respectively. The anterior column RoC was greater than 65mm in all cases. The minimum observed RoC for the path from one ilium, across the SI joint, the sacrum and to the other ilium was 71mm, with 99% of the cases having a RoC of at least 80mm, in both the inlet and outlet views. CONCLUSION: This study shows that if a flexible implant which could be stiffened once in place was available, it would enable the use of larger and longer fixation taking advantage of the pelvis's curved intracortical spaces. Even for dysmorphic pelves, accessible tunnels support a long, strong, curved fixation device.

Surgical treatment of a displaced lateral malleolus fracture: the antiglide technique versus lateral plate fixation.

OBJECTIVES: To assess the outcomes of the surgical management of "isolated" displaced lateral malleolar fractures, comparing the techniques of lateral plating and antiglide plating as described previously. DESIGN: This is a retrospective review, being largely a surgeon-randomized comparative study. SETTING: The study was carried out at a university teaching hospital that serves as a provincial trauma referral service and provides local community care. The senior surgeons are all orthopaedic trauma subspecialists. PATIENTS: A total of 193 patients meeting our inclusion criteria, with isolated lateral malleolus fractures surgically treated at the Vancouver General Hospital between 1987 and 1998, were studied. INTERVENTION: Eighty-five were treated with antiglide plating, whereas the remaining 108 patients underwent traditional lateral plating. MAIN OUTCOME MEASURES: The functional results were evaluated with the ankle scoring system described previously. We also compared the complication rates, including failure of fixation, infection, wound dehiscence, and need for hardware removal. RESULTS: Both groups were comparable for age, sex distribution, mechanism of injury, and occupation. There was no difference in ankle score, function, and infection rate. The incidence of wound dehiscence and reoperation for hardware removal was slightly higher in the lateral plate group, but the difference was not statistically significant. CONCLUSIONS: The outcome of the surgical management of a displaced lateral malleolus fracture is comparable with both techniques. Although few studies have reported some advantages using the antiglide technique, our data do not support one technique over the other.