Comparing Rates of Minimal Clinically Important Difference Between Manual and Robotic-Assisted Total Knee Arthroplasty.

Background: Differences in patient-reported outcome measures (PROMs) between manual total knee arthroplasty (mTKA) and robotic-assisted TKA (rTKA) have not been adequately assessed. We compared the minimal clinically important difference (MCID) for improvement (MCID-I) and worsening (MCID-W) between mTKA and rTKA patients.

Methods: Patients who underwent primary TKA (874 mTKA and 439 rTKA) with complete preoperative and 1-year postoperative PROMs were retrospectively identified using a multihospital joint arthroplasty registry. Patient-Reported Outcomes Measurement Information System Physical Function Short Form 10a (PROMIS PF-10a), PROMIS Global - Physical, or Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form were collected. The MCID-I, MCID-W, and "no significant change" rates were calculated using distribution-based methods. Propensity score matching was performed to control for confounding.

Results: Similar 90-day pulmonary embolism (P = 0.26), deep venous thrombosis (P = 0.67), and emergency department visit (P = 0.35) rates were found. The 90-day readmission rate for mTKA was 1.7 and 3.4% for rTKA (P = 0.08), and the overall revision rates were 2.2% for mTKA and 0.7% for rTKA (P = 0.07). Revision-free survival was 99% at one and 2 years for both groups (P = 0.65 and P = 0.43, respectively). There were no differences in the proportion of patients achieving MCID-I or MCID-W for PROMIS PF-10a, PROMIS Global - Physical, or Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form. The MCID-I for PROMIS PF-10a was achieved in 65.5 and 62.2% of patients who had mTKA and rTKA, respectively (P = 0.32).

Conclusions: Our study demonstrated similar complication rates and MCID-I and MCID-W attainment rates between mTKA and rTKA patients. Future studies should assess MCID attainment rates in the long term and in larger cohorts comparing mTKA and rTKA.