A Surgical Method to Establish a Murine Model of Knee Osteoarthritis using a Modified Hulth Procedure.

Knee osteoarthritis (KOA) is a chronic degenerative joint disease characterized by articular cartilage degeneration, subchondral bone remodeling, osteophyte formation, and synovitis, which is the most common type of osteoarthritis. This protocol presents a surgical method to establish a murine model of knee osteoarthritis using a modified Hulth procedure. Compared to injection-induced or conventional surgical models such as destabilization of the medial meniscus (DMM) and anterior cruciate ligament transection (ACLT), the modified Hulth model induces an earlier disease onset and more severe joint inflammation. By transecting the medial collateral ligament, medial meniscus, and anterior cruciate ligament, this method disrupts the mechanical alignment of the knee joint, thereby promoting OA progression. This model is particularly suitable for studying acute OA pathology and evaluating potential therapeutic interventions. To evaluate arthritis severity, we used small-animal ultrasound combined with three-dimensional (3D) reconstruction of the joint cavity to quantify its volume and assess synovial fluid accumulation. In addition, safranin-O/fast green staining of histological sections was performed for Osteoarthritis Research Society International (OARSI) scoring to evaluate cartilage destruction.