Correlation Between Patient-Reported "Happiness" With Knee Range of Motion and Objective Measurements in Primary Knee Arthroplasty.

BACKGROUND: The purpose of this study was to evaluate the correlation between objective knee range of motion (ROM) and patient "happiness" with knee ROM after total knee arthroplasty. METHODS: This was a retrospective review of all primary total knee arthroplasties from June through December 2019, yielding 902 patients (1,009 knees). Records were reviewed for knee ROM preoperatively and postoperatively at 6-week follow-up as well as whether patients self-reported being "Happy with their ROM" (HWROM). Clinical records were reviewed for documents ROM as well as manipulation under anesthesia (MUA). RESULTS: The mean preoperative ROM was 110 ± 16 degrees, and 40% of patients were happy with their ROM. Postoperatively, the mean ROM was 106 ± 13 degrees (P < .001), and 76% of patients were HWROM (P < .001). The mean change in knee ROM was (-) 5 ± 17 degrees. The mean postoperative ROM and change in ROM of patients who were HWROM after surgery were 109 ± 12 degrees and (-)2 ± 16 degrees. In patients not HWROM postoperatively, the mean ROM and change in ROM were 98 ± 14 degrees and (-)12 ± 18 degrees (P < .001). Patients with a lower preoperative ROM were statistically significantly more likely to have a positive change in their HWROM (f ratio = 41, P < .001). MUAs were performed in 7.2% of knees, and 28% of patients who underwent an MUA were HWROM before MUA. CONCLUSION: Early postoperative knee ROM was correlated with patient HWROM. However, further longer term follow-up and more detailed analysis of patient happiness with ROM are needed.