Anästhesie und klinische Forschung
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Comparing the Cumulative Pain Patients Experience Waiting for Knee Arthroplasty to their Postoperative Pain

Eric S. Schwenk, Franklin Dexter and Richard H. Epstein

Introduction: Reduction of pain is a major goal of anesthesiologists treating patients undergoing knee arthroplasty. This has traditionally been achieved through the use of regional analgesia. Although these techniques decrease postoperative pain, they inherently do not affect the longstanding pain patients experience as they wait for surgery. Our objectives were to quantify (1) the decrease in pain achieved by surgical joint replacement and (2) the decrease in postoperative pain achievable through femoral nerve blocks versus opioids. From a systems-based perspective, we wanted to determine how much reduction in waiting time before surgery would be necessary to achieve an equal cumulative pain decrease (i.e. pain x duration of pain) as that afforded by regional techniques in the immediate postoperative period.

Materials and methods: A systematic review using Pub Med was performed to obtain: (1) articles reporting preoperative pain scores for patients awaiting joint arthroplasty; (2) articles with knee arthroplasty patients who received femoral nerve blocks; and (3) articles providing duration on joint arthroplasty waiting lists. Cumulative pain was assessed by area under the response curve of pain scores vs. time, a methodology that is simple and valid. This was calculated by multiplying mean pain scores by the duration of pain.

Results: The decrease in knee pain subsequent to arthroplasty (6.4/10 vs. 2.9/10) is similar to the decrease in pain afforded by femoral nerve blocks for knee arthroplasty (4.7/10 vs. 2.0/10). Waiting times in many countries exceed 3 months. A decrease in waiting time by about 2 days results in a decrease in area under the curve comparable to that afforded by femoral nerve blocks.

Conclusion: Reducing waiting time for knee arthroplasty decreases total pain experienced by patients and is one systems-based approach that anesthesiologists could take to relieve pain. Further studies are needed to evaluate how best to accomplish this goal.