Abstract
Background
Since 1991 to 2008 approximately 800,000 Exeter stems have been sold worldwide with 80 reported cases of fracture (neck or stem). This study aimed to determine factors predisposing to fracture.
Method
Clinical, surgical, radiological and retrieval data was collated from Stryker Benoist-Girard and Exeter research databases. Risk factors associated with fracture were categorised to patient related (weight and activity levels), surgical related (poor medial support, component size, placement) and implant related (+ head).
Results
Data was available on 60 patients (28 stem, 32 neck fractures). Number of fractures per annum increased in proportion with sales. Mean patient age at fracture was similar for both neck and stem fractures (69yrs, 53–84; 67yrs, 30–89. p=0.56). 77% neck and 52% stem fractures occurred in males. Mean weight was 110kg (82–140) in neck and 91kg (70–126) in stem fractures with 68% neck and 38% stem fractures either obese or morbidly obese. Mean time to fracture was 78mths (36–144) for neck and 76 mths (2–155) for stem fractures. 76% of neck fractures occurred in stem sizes 44#2, 44#3 and 44¢4. Stem fractures occurred more commonly (85%) in the smaller sizes (35.5 to 44#1). A + head was used in 67% neck and 14% of stem fractures. Neck fractures were most commonly associated with patient (increased weight and activity) and implant related (use of a + head) factors. Stem fractures were most commonly associated with correctable surgical related causes predominantly secondary to stem undersizing or inadequate medial support.
Conclusion
Careful pre operative planning and templating is essential to identify those patients with pre-existing identifiable patient (weight, activity levels) and anatomical (proximal femoral canal morphology and offset) risk factors, to ensure appropriate stem selection and size (which may require a custom made implant) and meticulous placement and cementing technique in order to maximise fracture prevention.
