The optimal treatment for independent patients with a displaced
intracapsular fracture of the hip remains controversial. The recognised
alternatives are hemiarthroplasty and total hip arthroplasty. At
present there is no established standard of care, with both types
of arthroplasty being used in many centres. We conducted a feasibility study comparing the clinical effectiveness
of a dual mobility acetabular component compared with standard polyethylene
component in total hip arthroplasty for independent patients with
a displaced intracapsular fracture of the hip, for a 12-month period
beginning in June 2013. The primary outcome was the risk of dislocation
one year post-operatively. Secondary outcome measures were EuroQol
5 Dimensions, ICEpop CAPability measure for Older people, Oxford
hip score, mortality and re-operation.Aims
Patients and Methods
National registers compare implants by their revision rates, but the validity of the method has never been assessed. The New Zealand Joint Registry publishes clinical outcomes (Oxford knee scores, OKS) alongside revision rates, allowing comparison of the two measurements. In the two types of knee replacement, unicompartmental (UKR) had a better knee score than total replacement (TKR), but the revision rate of the former was nearly three times higher than that of the latter. This was because the sensitivity of the revision rate to clinical failure was different for the two implants. For example, of knees with a very poor outcome (OKS <
20 points), only about 12% of TKRs were revised compared with about 63% of UKRs with similar scores. Revision therefore is not an objective measurement and should not be used to compare these two types of implant. Furthermore, revision is much less sensitive than the OKS to clinical failure in both types and therefore exaggerates the success of knee replacements, particularly of TKR.
The Oxford hip and knee scores have been extensively used since they were first described in 1996 and 1998. During this time, they have been modified and used for many different purposes. This paper describes how they should be used and seeks to clarify areas of confusion.
