Abstract
Background: Medial patellar luxation (MPL) surgery in dogs commonly induces postoperative pain, inflammation and early joint dysfunction, which may contribute to long-term degenerative joint changes. Although NSAIDs are widely used, their limitations and adverse effects have led to increased interest in intra-articular therapies. Transforming growth factor-β1 (TGF-β1) plays a dual role in cartilage homeostasis, but its overexpression in osteoarthritis promotes cartilage degeneration via the Smad 1/5/8 pathway. The ELHLD peptide, a selective inhibitor of TGF-β1, has been developed to suppress this pathway while promoting cartilage regeneration. This study aimed to evaluate the effects of intra-articular ELHLD peptide on postoperative inflammation, pain and functional recovery following MPL surgery. Methods: This study was conducted in 15 dogs with bilateral grade II MPL undergoing corrective surgery. The right hindlimb was assigned to the treatment group (ELHLD peptide injection) and The left hindlimb was used as an untreated control, while ELHLD peptide (100 μg/kg) was administered intra-articularly immediately after surgery. Clinical evaluations included inflammatory index, muscle circumference of the femur (MCF), radiographic muscle width of the femur (MWF), range of motion (ROM) and owner-based gait scores. Measurements were performed preoperatively and at 2, 4, 6 and 8 weeks postoperatively. Result: At 2 weeks postoperatively, both groups showed increased inflammation and decreased joint function; however, the treated group exhibited a relatively smaller deterioration. The inflammatory index significantly decreased in the ELHLD-treated group compared to the control group at 6 and 8 weeks. Both MCF and MWF exhibited an initial decrease at 2 weeks, followed by a gradual increase. Notably, between 4 and 8 weeks, the treated group demonstrated a significantly greater recovery compared to the control group. ROM decreased by approximately 30% at 2 weeks in both groups but showed a significantly greater recovery in the treated group starting at 4 weeks, reaching near preoperative levels by 8 weeks. Gait scores also declined initially but improved progressively, with significantly higher scores in the treated group at 8 weeks. Overall, ELHLD peptide administration resulted in reduced postoperative inflammation and significantly enhanced recovery of stifle joint function compared to the control group.