Early clinical outcome and learning curve following unilateral primary total knee arthroplasty after introduction of a novel total knee arthroplasty system

ARTICLE HIGHLIGHTS

Research background

Globally, the use of total knee arthroplasty (TKA) has risen throughout the last 2-3 decades and is projected to increase even further. The introduction of novel implants for TKA is a frequent occurrence with proposed benefits for patients, but is unfortunately sometimes contradicted by evidence of undesirable effects with regard to revision rates, costs, and patient-perceived outcomes. Little information exists on how early surgical outcome and implant positioning are affected following the introduction of a novel TKA system.

Research motivation

This study focused on the early logistical challenges posed by the introduction of a novel TKA system. In particular, the short-term clinical outcomes in patients with emphasis on how surgery-related factors and implant positioning are affected following the introduction of a novel TKA system. The utilization rate across surgeons and how surgical experience with the implant affects outcome were investigated.

Research objectives

This short-term study showed that a learning curve is present even for experienced knee surgeons following the introduction of a novel knee system. Information from this study may help to increase care when introducing new procedures and logistical considerations when choosing a novel implant, as small gains in alignment should be balanced against inferior peri-operative outcomes. These findings will be useful as a basis for comparisons for future studies and correlations with patient reported outcomes.

Research methods

This retrospective study included 212 TKA patients undergoing surgery at Copenhagen University Hospital Hvidovre. We included 75 consecutive knees treated with the novel TKA system in the introduction period starting from November 30th 2015 immediately following implementation by three experienced surgeons (25 TKAs/surgeon), along with a control group of 75 patients. A Follow-up Group consisting of 62 consecutive knees starting from 365-d after each respective surgeon ended their initial 25 novel TKAs was also included. Patient demographics, surgery-related factors and alignment data were recorded using the institution’s patient registry.

Research results

This study examined how early clinical outcome, implant positioning and utilization rate were affected by the introduction of a novel TKA system between August 2015–December 2018, and how increased surgical experience with the implant affected patient outcome. The novel TKA system was utilized in 69% (71%), 53% (54%), and 45% (75%) of primary TKA procedures by the three surgeons, respectively (Follow-up Group). Mean surgery time was increased by 28% and mean intra-operative blood loss by 25% in the Introduction Group, whereas only the mean surgery time was increased in the Follow-up Group by 18%. Small improvements were observed in alignment. FF outliers were reduced in the Introduction Group with a more pronounced decrease in the Follow-up Group.

Research conclusions

Little information exists on how early surgical outcome is affected following the introduction of a novel TKA system. This study brings a unique view on short-term outcome following the introduction of a novel TKA system in relation to implant positioning, early clinical outcome and the learning curve. It accounts for variances between surgeons by studying the same experienced orthopedic surgeons throughout the study, as surgical skill, experience, and caseload varies across surgeons. Increased surgical time and intraoperative blood loss was observed immediately after introduction of the new system. These differences diminished one year after introduction of the new implant.  Our findings suggest that surgeons should take increased care when introducing new procedures and consider the logistics when choosing a novel implant, as small gains in alignment should be balanced against inferior peri-operative outcomes.

Research perspectives

Further studies are needed to investigate if these differences persist over time and correlate with patient reported outcomes.