Rationalisation of primary hip replacement using evidence from linked national databases

Abstract

End-stage osteoarthritis of the hip can be treated effectively with hip replacement. Many implant brands are available with multiple component options including different methods of fixation, femoral head size and articulating surface materials. The costs of these implant components vary dramatically. Surgical outcome can be assessed variously by functional and quality of life scores, risk of failure over time requiring revision surgery, post-operative mortality and complications (such as wound infections), and readmission to hospital. Patient expectation, perception of success and the satisfaction with surgery are also important metrics. Surgeon and patient characteristics may influence these outcomes.
Health systems under considerable financial pressure are confronted with an aging population with increasing need for joint replacement surgery. In response, efficient, rationalised provision of services is required. The most cost-effective procedures combine the best implant survival rates (and hence the fewest revisions) and patient outcomes with the lowest mortality, complications and costs.
To establish the benefits and relative performance of different hip implants, large patient numbers and long term follow-up are required, limiting the use of experimental studies. Joint registries and other large collections of data play a pivotal role in providing evidence of efficacy, although careful statistical analysis is required to ensure findings are robust. Through a series of examples, this thesis illustrates the potential of such analyses to appropriately inform patient care and explores the issues surrounding the use of these large datasets.
Despite a global trend favouring cementless implants, hard bearings and larger head sizes, a cemented hip replacement with a taper slip stem, a metal-on-polyethylene bearing and a 28mm head offers equivalent or better outcomes for the vast majority of patients. Cost data from the NHS suggest these implants are also the cheapest to purchase. Young females have marginally better functional outcomes following cementless or hybrid replacement, but clinically this may not be important, and costs are higher. Standardisation of hip replacement type across all patients is likely to improve outcome, reduce error and enhance training.
The posterior approach provides a marginally better functional outcome compared with the direct lateral approach. Patients with a high BMI have greater risks of complications with only slightly poorer improvement in function. Implant characteristics appear to have little or no influence on patient outcomes. Interpretation of outcome measures is complex, requiring a greater understanding of the interactions between surgical and patient factors.
This thesis provides evidence to inform decision-making by surgeons, professional bodies and healthcare providers when offering hip replacement to patients with osteoarthritis.