Abstract
Introduction
With the introduction of new technology in orthopaedics, surgeons must balance anticipated benefits in patient outcomes with challenges or complications associated with surgical learning curve for the technology. The purpose of this study was to determine whether the surgeon learning curve with a new multi-radius primary TKA system (primary TKA implant and instruments) designed for surgical team ease would impact clinical outcomes, surgical time and complications.
Materials & Methods
From November 2012 to July 2015, 2369 primary TKAs were prospectively enrolled in two multicenter studies across 50 sites in 14 countries with a new knee system (ATTUNE®) evenly balanced across four configurations: cruciate retaining or posterior stabilised with either fixed bearing or rotating platform (CRFB, CRRP, PSFB, PSRP). 2261 knees had a <1 year visit and 1628 had a greater than 1 year visit. These knees were compared to a reference dataset of 845 primary TKAs from three manufacturers in the same four configurations with currently available products (CURRENT-TKA). Demographics for ATTUNE and CURRENT-TKA were similar and typical for primary TKA. Operative times, clinical outcomes and a series of five patient reported outcomes were compared for ATTUNE vs. CURRENT-TKA. The first 10 ATTUNE subjects for each surgeon were defined as learning curve cases (N=520) and were compared to all later subjects (N=1849) and also with the CURRENT-TKA cases (N=845). Patient reported outcome measures and clinical outcome analyses were adjusted for covariates including patient demographics, pre-op assessment and days post-op.
Results
Mean (SD) surgical time for ATTUNE learning curve cases was 79.3 (24.7) minutes, which reduced thereafter to 73.6 (24.3) (p<0.001). Beyond 10 cases, there was a continued reduction in ATTUNE surgical time (R-Squared = 0.031). After 10 cases, surgical time was on par with the mean (SD) 72.0 (21.7) for CURRENT-TKA (p=0.097).
PROM outcomes of the first 10 learning curve cases for ATTUNE were not statistically different from later cases at less than 1 year or later when adjusted for relevant covariates including configuration, patient demographics, pre-op functional status, and time post-op (p-values > 0.01). PROM outcomes for ATTUNE vs. CURRENT-TKA under the same covariate adjustments showed a trend favoring KOOS ADL, Symptoms, and Sport and Recreation subscores at minimum 1 year (p-values < 0.05).
The incidence of intraoperative operative site (knee) complications was 1.3% (7/520) for the ATTUNE learning curve cases which was similar to both the 0.6% (5/845) rate for historical CURRENT-TKA (p=0.230) and the 0.8% (14/1849) intraoperative complication rate for the ATTUNE later cases (p=0.195).
Discussion
The introduction of new implants into the market place needs to have adequate data to support that they are safe and effective. Except for a minor increase in surgical time during the first 10 patients, this study found that surgeon learning curve with the new ATTUNE primary TKA system does not adversely affect patient short term outcomes and complication rates.
