Does Prior Arthroscopy Delay Clinically Relevant Improvement Timelines Following Unicompartmental Knee Arthroplasty...

Prior knee arthroscopy before total knee arthroplasty (TKA) may lead to worse patient-reported outcomes. However, the impact of prior arthroscopy on unicompartmental knee arthroplasty (UKA) is unclear. Moreover, to our knowledge, no previous investigation has examined how prior arthroscopy is associated with the time to achieve the minimal clinically important difference (MCID). Thus, this study investigated whether prior arthroscopy is associated with the time to MCID achievement after both UKA and TKA.

We conducted a retrospective analysis of a prospectively maintained multi-institutional arthroplasty registry. A total of 55 UKA and 136 TKA patients underwent prior arthroscopy within 1 year, while 51 UKA and 83 TKA patients underwent prior arthroscopy between 1 and 2 years. A one-to-four propensity-score match identified UKA and primary TKA patients who had similar characteristics, but no prior arthroscopy. Patients completed the Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form preoperatively and at multiple time points postoperatively.

Arthroscopy was not associated with a delayed time to MCID for UKA, whether performed within 1 year (3.03 to 3.04 versus 3.03 to 3.04 months; P = 0.82) or 1 to 2 years prior (3.31 to 3.37 versus 1.67 to 1.84 months; P = 0.77). In contrast, arthroscopy within 1 year before TKA was associated with a delayed time to MCID (2.07 to 2.17 versus 0.96 to 0.97 months; P = 0.015), whereas arthroscopy 1 to 2 years prior to TKA was not associated with a delayed time to MCID (3.03 to 3.04 versus 2.37 to 2.41 months; P = 0.93).

Arthroscopy performed within a year prior to TKA was associated with a delayed improvement timeline, yet this delay was diminished if arthroscopy was performed beyond 1 year prior. Prior arthroscopy did not delay the time to MCID for UKA.