Femoroacetabular Impingement Rabbit Model Induced by Exercise and Mechanical Stimulation

BACKGROUND: Femoroacetabular impingement (FAI) is one of the major causes of hip pain. The pathogenesis of FAI remains unclear, and few animal models are available to study its mechanisms. PURPOSE: To evaluate bone deformity formation, labrum, and articular cartilage injury induced by mechanical and exercise stimulation, and to establish an FAI model in New Zealand White rabbits. STUDY DESIGN: Controlled laboratory study. METHODS: 6-month-old (6M) and 1-month-old (1M) male rabbits were used. Three-dimensional printed polylactic acid scaffolds were surgically fixed to the acetabular rim, followed by postoperative treadmill training. Specimens were collected at 8 and 12 weeks. Bone deformities were assessed by micro-computed tomography. Histological evaluation included hematoxylin and eosin staining for morphology, Safranin O/Fast Green (SO/FG), and toluidine blue staining for proteoglycan and glycosaminoglycan deposition, and immunofluorescence for SRY-box transcription factor 9 (SOX9), aggrecan (ACAN), runt-related transcription factor 2 (RUNX2), and cluster of differentiation 31 (CD31) expression. Mechanical properties of the labrum and cartilage were evaluated by nanoindentation, with the Young's modulus as the stiffness parameter. RESULTS: = .0061) and femoral head cartilage was reduced. CONCLUSION: A stable, reproducible, and easily operable rabbit model of FAI was established using combined mechanical and exercise stimulation, providing a practical platform for investigating the pathogenesis of FAI. CLINICAL RELEVANCE: FAI animal models established through acetabular overcoverage surgery are expected to provide an effective tool for subsequent research into the pathogenesis of FAI, thereby laying a theoretical foundation for its early targeted treatment.