Impact of Age, Gender and Anesthesia Modality on Post-Operative Pain in Total Knee Arthroplasty Patients

Optimizing pain control following total knee arthroplasty is of utmost importance to the immediate post-operative course. Various anesthesia modalities are available, but studies comparing multiple anesthesia modalities, patient age, and sex are limited.

The purpose of our study was to examine the impact of patient age, gender, and perioperative anesthesia modality on postoperative pain following primary total knee arthroplasty.

443 patients who underwent primary total knee arthroplasty by 14 surgeons with some combination of general anesthesia, spinal anesthesia, femoral nerve block, and intrathecal morphine were identified. Anesthesia route and type, length of surgery, post-operative patient-reported pain measures using the Visual Analog Scale, opioid consumption, and length of hospital stay were recorded for each patient and used to compare differences among study groups.

No significant differences were noted between anesthesia groups with regards to postoperative pain or length of hospital stay. Patients receiving spinal anesthesia and femoral nerve block without intrathecal morphine were significantly older than other groups. Patients receiving general anesthesia required significantly more daily intravenous morphine equivalents than patients receiving spinal anesthesia. Patients receiving spinal anesthesia with femoral nerve block and intrathecal morphine consumed the least amount of morphine equivalents. When comparing males and females among all groups, females had significantly higher pain ratings between 24-36 and 24-48 hours postoperatively.

Although no significant differences were noted on pain scores, patients who received spinal anesthesia with intrathecal morphine and femoral nerve block used less narcotic pain medication than any other group. Females reported significantly higher pain between 24-48 hours post-op compared with males but not significantly greater anesthetic usage.

Level III, Therapeutic Study, (Retrospective Comparative study).