KS18: LEARNING CURVES IN UKA

Abstract

There is suggestion our National Joint Replacement Registry (ANJRR) does not recognize ‘the surgical learning curve’ for new prostheses. Prostheses introduced post-Registry have the learning curve revisions captured. Prostheses introduced pre-Registry will not and will be advantaged. This paper presents the evidence for this and makes suggestions to correct this issue. A literature search was made for surgery learning curve references. The Swedish Knee Arthroplasty Register was reviewed for learning curve references. The ANJRR reports were examined for evidence of learning curve revisions inclusion in cumulative revision rate curves using Unicompartmental Arthroplasty data. An Internet search reveals 212 references on ‘surgery learning curve’. Some discuss the particular issue of minimally invasive surgery (MIS). The 2004 Swedish Knee Arthroplasty Register (SKAR) report mentions the trend towards increased revision rates when Unicompartmental Arthroplasty was inserted with MIS. The 2006 SKAR report discussed this issue further suggesting the method may initiate a new learning process which can be shortened if the surgeons are offered training before they start using the method. In 2004 the Australian National Joint Replacement Registry report showed that a new Unicompartmental Arthroplasty (Preservation) had a high early revision rate. This prosthesis was launched in 2002 as a minimally invasive product. That report data was used by several prostheses companies and surgeons to widely highlight the prosthesis “poor performance”. The 2007ANJRR report shows that Preservation now has the lowest 2 to 4 year revision rate of all Unicompartmental prostheses. If the surgery learning curve was excluded the prosthesis would not have been disadvantaged in its early data reports. The evidence is that the learning curve exists and disadvantages new prostheses in ANJRR reporting. This now discourages prosthesis companies from launching new products here. Solutions recommend are:

1. The ANJRR accept and support the issue of “the learning curve” and the adverse impact this has on post ANJRR prosthesis revision rate data & graphs compared with pre ANJRR prostheses.

2. The first 2 years results of the new prostheses be monitored and discussed with vendors and early evaluators but not reported.

3. The first 2 years of revisions be “quarantined” from subsequent ANJRR reporting so that pre and post ANJRR prostheses are on an “level playing field.”