UCSF

Objective

Total knee arthroplasty is a painful procedure. No studies have evaluated modifiable predictors of acute postoperative pain trajectories during hospitalization.

Methods

Consecutive patients (N = 188) were enrolled in a longitudinal cohort study and completed a demographic questionnaire, as well as the Brief Pain Inventory, Hospital Depression and Anxiety Scale, Lee Fatigue Scale, Fatigue Severity Scale, and Brief Illness Perception Questionnaire on the day before surgery. Clinical data were extracted from medical records.

Setting and patients

Each patient completed a pain diary that assessed pain at rest and with activity, and hours per day in pain every evening from day of surgery until postoperative day 3. Using hierarchical linear modeling, we investigated which demographic, clinical, symptom, and psychological characteristics predicted initial levels as well as the trajectories of acute pain at rest and with activity, and hours per day in pain.

Results

Higher levels of all three acute pain characteristics on the day of surgery resulted in worse trajectories. Higher pain scores with rest and with activity on the day of surgery were associated with more days with femoral block, higher average dose of opioids, and higher emotional response to osteoarthritis. Higher number of comorbidities, higher average dose of opioids, and lower perceived control predicted more hours per day in pain on the day of surgery.

Conclusions

This study identified several potentially modifiable predictors of worsening pain trajectories following total knee arthroplasty. Optimal pain management warrants identification of these high-risk patients and treatment of modifiable risk factors.