Introduction: An increasing number of young and active patients are undergoing total hip replacement (THR), placing greater demands on the longevity of the implant. One of the most common modes of failure of a THR is aseptic loosening secondary to wear. This study aims to evaluate wear rates seen in a ceramic on polyethylene bearing, and to produce a mathematical model that could be used to predict wear which would have a role in a day-to-day clinic environment.

Methods: Radiographs were examined from 59 uncemented total hip replacements performed between March 1993 and April 2004 comprising a ceramic head on a polyethylene liner. Wear measurements were made using a manual Livermore technique employing digital callipers (accuracy 0.01mm). Multiple radiographic parameters were analysed so that those affecting wear could be identified and included in a mathematical model to predict wear.

Results: 59 hips were measured in 43 patients. Average age at time of follow-up was 53 (34–76). The mean length of time between postoperative and follow-up x-rays was 53 months (11–162). Overall wear rates were 0.05mm/year and total wear increased with the length of time an implant had been in place. There was no correlation between femoral stem alignment or acetabular inclination and wear rates. Multivariate linear regression analysis revealed that sex and cup type were significant contributing variables to wear. A predictive model was produced with an R2 value of 0.543.

Conclusion: This study confirms low wear rates with a ceramic on polyethylene bearing. The mathematical model produced can predict the variability of wear in 54.3% of hips. Further refinement may enable the model to be used to identify risk factors and therefore patients that require greater scrutiny at follow-up.

Early discharge from hospital has the potential to reduce direct costs, but may result in patients being discharged without adequate preparation for a return to the community. This qualitative study aimed to investigate patient expectations of and satisfaction with in-hospital discharge planning after hip arthroplasty in early and late discharge patient groups. A prospective study of 33 consecutive patients requiring hip arthroplasty were recruited from two tertiary hospitals in the lower North Island. Participants were interviewed using in-depth, semi-structured interviews on the day of discharge from hospital and again four-eight weeks later. Comparative analysis of the interviews from patients in early and late discharge groups was made.

Findings reveal good levels of satisfaction with discharge planning for patients in both early and late discharge groups, facilitated by the opportunity to attend a pre-assessment clinic. Discharge planning was viewed as a partnership between patients and key members of the multi-disciplinary team. While written information provided was timely, restricted opportunity for dialogue with health professionals limited patient knowledge and understanding of recovery. Different needs of participants indicate that discharge planning needs to be tailored and more responsive to individuals. The role of health professionals as a mentor-coach is pivotal. Further interaction from health professionals, as a follow-up to written information provided may be a way to improve the discharge process and lead to more consistent outcomes.