Outcomes of Computer-Assisted Surgery Compared with Conventional Instrumentation in 19,221 Total Knee Arthroplasties

Background: Studies have shown improved alignment in association with the use of computer-assisted surgery (CAS) as compared with conventional instrumentation during total knee arthroplasty (TKA) but have failed to show a consistent clinical benefit. The aim of the present study was to compare the revision rates and functional outcomes following TKA performed with either CAS or conventional instrumentation. Recognizing that selection bias may arise from the preferential use of CAS in difficult or complex cases, the implant survival data and postoperative functional scores were analyzed with reference to whether the surgeon routinely performed TKA with use of CAS or conventional instrumentation.

Methods: Revision rates and functional data in terms of the Oxford Knee Score (OKS) at 6 months, 5 years, and 10 years were obtained from the New Zealand Joint Registry (NZJR) for 19,221 TKAs performed from 2006 to 2018.These data were analyzed by comparing 2 cohorts of patients: those managed by high-volume surgeons who routinely used CAS (“routine CAS” surgeons) and those managed by high-volume surgeons who routinely used conventional instrumentation (“routine conventional” surgeons). The mean duration of follow-up was 4.5 years (range, 0 to 12 years).

Results: The revision rate per 100 component-years was 0.437 for the “routine CAS” surgeons, compared with 0.440 for the “routine conventional” surgeons (p = 0.724). For patients <65 years of age, the revision rate per 100 component-years was equivalent for the “routine CAS” and “routine conventional” surgeons (0.585 compared with 0.508; p = 0.524). The OKS scores were similar at 6 months (38.88 compared with 38.52; p = 0.172), 5 years (42.26 compared with 41.77; p = 0.206), and 10 years (41.59 compared with 41.74; p = 0.893) when comparing the 2 cohorts. Surgeons who had performed >50 TKAs with use of CAS took 10 minutes longer on average than those who used conventional instrumentation (92 compared with 82 minutes; p = 0.012).

Conclusions: The present study demonstrated no difference in survivorship or functional outcome scores to support using CAS for TKA. Experienced surgeons using CAS had longer operative durations than comparable surgeons using conventional instrumentation.

Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.