Local Inflammatory and Metabolic Response in the Knee Synovium After Arthroscopy or Arthroscopic Anterior Cruciate Ligament Reconstruction

Purpose: The aim of this study was to study local synovial metabolism and inflammation after arthroscopy and arthroscopic anterior cruciate ligament (ACL) reconstruction. Methods: Microdialysis in the synovial membrane was performed during 4 hours postoperatively in 20 patients undergoing a minor arthroscopy procedure (e.g., meniscus surgery and 10 patients undergoing ACL reconstruction with a quadruple hamstring graft). Contralateral thigh adipose tissue served as a reference. Lactate, glucose, glycerol, and prostaglandin E2 (PGE2) were monitored. The ACL group received intra-articular morphine preoperatively, and a cooling and compression device was applied postoperatively according to local clinical routines. Results: The synovial lactate levels and the consumption of synovial glucose was increased postoperatively in the arthroscopy group compared to the reference adipose tissue. There were no significant differences regarding synovial levels of glycerol, lactate, or glucose compared to the reference tissue in the ACL group. PGE2 levels were significantly lower in the ACL group compared to the arthroscopy group. Conclusions: A major arthroscopic surgical procedure (ACL reconstruction) did not increase the local synovial metabolism or induce a detectable inflammatory response compared to a minor arthroscopic surgical procedure (e.g., meniscal surgery) in our clinical setting. Intra-articular injection of morphine and or the use of a combined cooling and compression device in the ACL group showed a modulation of the response in tissue chemistry as measured by synovial microdialysis. Level of Evidence: Level III, therapeutic case-control study.