The effects of morphine on human articular cartilage of the knee: An in vitro study

Purpose: The purpose of this study was to determine the metabolic, histologic, and ultrastructural effects of morphine and its combination with saline and bupivacaine on human articular cartilage. Type of Study: In vitro study. Methods: Nonfibrillated human articular cartilage was harvested and transferred into an experimental culture consisting of a control medium, saline, or a combination of morphine/saline or morphine/saline/bupivacaine for 12, 24, or 72 hours. Each sample was radiolabeled to assess proteoglycan synthesis. Histologic and ultrastructural effects were also examined. Results: We found a significant, dose-related, transient decrease in (SO4)-S-35 incorporation in the morphine/saline samples at 12 hours, and in the saline only samples at 24 hours. We found no evidence of histologic or ultrastructural damage to the cartilage. Conclusions: Morphine and saline can both produce a transient decrease in (SO4)-S-35 incorporation that normalizes by 72 hours. This study does not suggest any contraindication to the use of intra-articular morphine as a postoperative analgesic.