Metaphyseal debonding of the Corail collarless cementless stem: REPORT OF 18 CASES AND CASE‐CONTROL STUDY

Aims The Corail stem has good long‐term results. After four years of using this stem, we have detected a small group of patients who have presented with symptomatic metaphyseal debonding. The aim of this study was to quantify the incidence of this complication, to delineate the characteristics of patients presenting with this complication and to compare these patients with asymptomatic controls to determine any important predisposing factors. Patients and Methods Of 855 Corail collarless cementless stems implanted for osteoarthritis, 18 presented with symptomatic metaphyseal debonding. A control group of 74 randomly selected patients was assembled. Clinical and radiological parameters were measured and a logistic regression model was created to evaluate factors associated with metaphyseal debonding. Results The prevalence of this complication was 2.1% in our series. In the multivariable model, the presence of a Dorr B‐type proximal femur was associated with metaphyseal debonding (odds ratio (OR) 10.73, 95% confidence interval (CI) 2.31 to 49.97, p = 0.002), as was a body mass index > 25 kg/m2 (OR 6.85, 95% CI 1.06 to 44.28, p = 0.04). Smaller stems and the use of a polyethylene acetabular liner appeared to be protective when compared with metal and ceramic setting hard‐on‐hard bearings. Conclusion We have described an uncommon but important mode of failure of the Corail stem. Surgeons should be aware of this phenomenon; overweight patients with Dorr B‐type femurs and in whom hard bearings are used appear to be particularly at risk.