Abstract
Introduction and Aims: Periprosthetic fracture is a serious complication of increasing incidence in joint replacement. Our aim was to evaluate periprosthetic fracture patterns in our series of 1152 primary hip arthroplasties using a cementless proximally hydroxyapatie coated anatomic stem and to identify risk factors from parameters measured in our assessment of these patients.
Method: All patients with periprosthetic fracture following primary total hip arthroplasty using the Anatomique Benoist Girard I (ABG I) hip system were identified. Parameters studied included time of fracture after surgery, patient age and fracture classification. The pre-operative cortical index in the fracture group was measured and compared with a group matched for age, gender, diagnosis, and body mass index.
1152 ABG I primary hip arthroplasties were performed in 1037 patients from 1991–1997. Osteoarthritis was diagnosed in 93% of cases. The average age was 65 years; there were 536 females and 501 males. Mean follow-up was 79.6 months.
Results: Thirty-two patients, 16 male and 16 female, suffered a periprosthetic fracture. Thirty-one patients were treated for osteoarthritis and one for a femoral neck fracture. We retrieved complete records on 28 patients.
The average age of the fracture group was 73 years, compared to 65 years for the whole series (p< 0.0001). The incidence of periprosthetic fracture increased with age. The relative risk for patients over 70 years for peri-prosthetic fracture is 4.7 greater (95% CI 2.14–10.21).
Distinct fractures patterns were related to time from initial surgery. Four fractures occurred within three months of surgery; these early fractures exhibited a particular pattern. The remaining 24 occurred between four and 114 months after surgery. These late fractures exhibited a different but consistent fracture pattern. Two fractures in the early group were identified immediately post-operatively. All others presented after minor low energy trauma.
The mean cortical index in the fracture group was 47% and in the matched group 51%. If the pre-operative cortical index is below 50%, the risk of periprosthetic fracture is 4.75 greater (odds ratio 4.75 CI 1.5–15.00).
All fractures were adequately classified and managed by guidelines in the Vancouver classification.
Conclusion: This study identified distinct fracture patterns related to time from surgery. Cortical index and age have predictive value in pre-operative assessment of fracture risk: cortical index below 50 and age above 70 are risk factors for periprosthetic fracture and should be considered with other parameters to minimise risk of this complication.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
