Abstract
Introduction
The results of cementless total hip arthroplasty (THA) vary with data from the UK national Joint Registry being less favourable than that from the Australian registry. The senior author started using a fully cementless THA in 2005 and we aimed to gauge the performance of the implants based on their revision data.
Patients and methods
Between August 2005 and March 2015, 4,802 primary THA (4,309 patients) were performed with a cementless Corail® stem and a cementless Pinnacle® cup. There were 2,086 (43.4%) males and 2,716 (56.6%) females with a median age of 70 years (IQR 13, Range 16–95). There were a number of changes to the surgical technique with respect to the Corail® stem during the ten-year period, which we have categorised as phase 1 and phase 2. We compared the data in the two phases. Data were extracted from a prospectively maintained patient information database.
Results
A total of 80 (1.67%) revisions have been performed to date (median follow-up 65.9 months, IQR 46.8, Range 0 to 121), which is equivalent to a cumulative revision risk of 2.5% at ten years. Revision rate was not significantly different in those less than 70 years old (1.63%) compared to those greater than or equal to 70 years old (1.76%, P=0.81). The leading causes of revision were instability (n=22, 0.46%), infection (n=20, 0.42%) and aseptic loosening of the stem (n=15, 0.31%). More collarless stems than collared stems have been revised. Phase 2 changes in surgical technique resulted in cessation of collarless stem use, a small but significant increase in mean stem size, and a paradoxical decrease in iatrogenic femoral fracture.
Conclusions
The overall revision rates of the Corail® stem and Pinnacle® cup in this series are comparable to the best performing THA in equivalent registry data. Instability was the leading cause of revision but these data did not identify a causative factor. The changes in infection rate in this series are possibly influenced by changes in local antibiotic prophylaxis policy. There is a learning curve for the cementless stem as seen here by a reduction in revisions for aseptic loosening and iatrogenic femoral fracture during the ten-year period. We believe that collared stems, avoidance of undersizing and surgical technique focusing on primary stability are the key aspects.
