The purpose of this study was to describe patterns of pain during the first year following total knee arthroplasty (TKA) and evaluate pre- and postoperative factors associated with pain and patient satisfaction at 1 year. It was hypothesized that more severe preoperative pain would be associated with more residual pain and lower patient satisfaction 1 year after surgery.
A longitudinal cohort study was performed with repeated measures of pain (0-10 numeric rating scale) and evaluation of other self-reported symptoms (Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index, and Fatigue Severity Score), daily functioning (Lawton Instrumental Activities of Daily Living Scale), quality of life (EQ-5D-3L), knee function (KSS Knee and Function Score), perioperative and clinical characteristics (e.g. surgery duration, brand of implant, comorbidities), biochemical parameters (haemoglobin, C-reactive protein, creatinine), and patient satisfaction (20-item scale). Post-surgical improvement was defined as at least a two-point decrease in the patient's rating of pain interference with walking from baseline to 1 year. Hundred patients (mean age 64 ± 8 years and 93% female) consecutively admitted for uncomplicated primary TKA participated, and 79 with complete data were included in this analysis.
Pain generally decreased during the first postoperative year, from an average rating of 6 (SD = 3) to 1 (SD = 2). However, 18 of the 79 patients experienced no improvement in pain from baseline to 1 year. Factors associated with non-improvement of pain interference with walking after TKA included lower preoperative ratings of pain interference with walking (p < 0.001) and lower preoperative ratings of average pain (p = 0.004), active or very active levels of preoperative physical activity (p = 0.017), and higher ratings of worst pain on the first three postoperative days (p = 0.028). Pain at 1 year was the only predictor of lower patient satisfaction at 1 year.
Prognostic study, Level II.
Patients with low preoperative pain ratings or high preoperative levels of physical activity are at increased risk of non-improvement in knee pain after TKA. This finding should be taken into consideration when selecting appropriate candidates for TKA surgery. Orthopaedic surgeons should pay particular attention to patients reporting low pain interference with walking and consider other conservative or surgical treatment options before TKA. Effective strategies for detection and treatment of TKA patients with high pain ratings at early follow-up visits also need to be developed.