Patient-Reported Mental Health Score Influences Physical Function After Primary Total Knee Arthroplasty

Despite the effectiveness of total knee arthroplasty (TKA), patients often have lingering pain and dysfunction. Recent studies have raised concerns that preoperative mental health may negatively affect outcomes after TKA. The primary aim of this study investigates the relationship between patient-reported mental health and postoperative physical function following TKA.

A retrospective study of 1392 primary TKA patients was performed. Mental health and physical function scores were measured using the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health, and PROMIS Physical Function 10a and Knee injury and Osteoarthritis Outcome Score Physical Function (KOOS-PS) short forms. These assessments were completed preoperatively and up to 1-year postoperatively. Patients were stratified based on preoperative mental health scores into five distinct categories ranging from “Poor” to “Excellent.” Locally estimated scatter plot smoothing curves (LOESS) were fit to the data examining physical function score trends over time.

Patients with higher mental health scores before surgery demonstrated better preoperative and postoperative physical function scores. However, all patients experienced similar gains in physical function following surgery. Despite this early improvement, patients with the worst mental health scores experienced a sharp decline in physical function approximately a year after surgery and did not appear to recover.

Poor mental health should not be a contraindication for performing TKA. For patients with the lowest mental health scores, physicians should account for the possibility that physical function scores may deteriorate a year after surgery. Tighter follow-up guidelines, more frequent physical therapy visits, or treatment for mental health issues may be considered to counter such deterioration.