Extrapolation of an Experimental Model of Bone Marrow Lesions Using the Rat Femoral Condyle. Stewart HL1, Sikes KJ1, Serkova NJ2, Easley JT1, Kawcak CE1. 1Colorado State University, Department of Clinical Sciences, Fort Collins, CO; 2University of Colorado, Anschutz Medical Campus, Departments of Radiology and Radiation Oncology, Aurora, CO.
Bone marrow lesions (BMLs) are well reported to cause pain and result in morbidity across species; and appear to be early indicators of inflammation accelerating degenerative changes within the joint. The investigators have previously developed a reproducible experimental model for BMLs using the ovine stifle (knee) joint, but have not evaluated the applicability of this model across other species. The objective of this study was to develop an experimental model for BMLs using the rodent stifle and to understand the clinical manifestations associated with BML generation. Four skeletally-mature, male Sprague Dawley rats were used for this prospective study. BMLs were bilaterally induced using a 22-gauge needle penetrating through the articular cartilage and into trabecular bone. Magnetic resonance imaging (9.4 T) was performed preoperatively, and at 3, 14, 45, and 90 days postoperatively. Gait analysis was performed weekly. Animals were euthanized at 14 (n = 1), 45 (n = 1) or 90 (n = 2) days postoperatively. BMLs were reliably generated in the medial femoral condyle of all rats within 14 days of surgery, with a more defined area of signal intensity over time. Gait analysis revealed a significant (P = 0.01) increase in the stride velocity in the forelimbs compared to baseline and compared to the hind limbs over time. Taken together, this study confirms an experimental model for BMLs in the rodent stifle is possible, and BMLs may result in compensation in nonaffected limbs. A rodent BML model provides further insight into the clinical impact of this condition.