UCSF

Background

Moderate/severe pain after total knee arthroplasty (TKA) is a poor surgical outcome. Many studies have identified preoperative risk factors of pain after TKA, but studies of the joint contributions of co-occurring symptoms are lacking.

Methods

Patients undergoing primary TKA (n = 202) were enrolled in a longitudinal cohort study. Preoperatively, patients completed questionnaires measuring demographics and symptoms (pain, fatigue, sleep problems and depression). Pain was re-assessed 12 months after TKA. Logistic regression analysis was used to compute the probabilities of moderate-severe pain at 12 months based on preoperative symptom levels, and results were combined into a risk matrix.

Results

More than one-third (40%) of patients (n = 187) reported moderate-severe pain after TKA. Among preoperative risk factors included in the logistic regression analyses were age, sex, pain, fatigue, sleep problems and depression. Adjusting for possible confounders, fatigue (p = 0.02) and pain (p = 0.01) were significant risk factors for moderate-severe pain at 12-months follow-up and were retained in the final risk matrix. The co-occurrence of high-preoperative fatigue and pain scores resulted in 57% estimated probability of moderate-severe pain at 12 months. Similarly, the co-occurrence of low-preoperative fatigue and pain scores resulted in 14% estimated probability of moderate-severe pain 12 months after TKA.

Conclusion

The combination of high fatigue and pain scores prior to surgery was a key risk factor for moderate-severe pain 12 months after TKA. Mapping of these factors could be used preoperatively to identify patients who are at risk to experience a poor outcome of TKA.