A mouse growth plate injury model identified contributions of <i>pdgfra</i> and <i>pdgfrb</i> cellular descendants to bony bar formation

Growth plate injuries in pediatric patients can lead to serious musculoskeletal complications, such as bony bar formation and potential growth arrest. Current clinical treatments have significant limitations, necessitating improved research models. The present study developed a highly reproducible drill-hole injury model in the mouse distal femur and introduces a quantitative scoring system for assessing bony bar formation. Using micro-computed tomography (μCT) and histological analyses, we demonstrate a progressive increase in bone tissue formation over a 42-day period. A 5-point grading system was developed to evaluate bony bar extent, validated through radiological and histological comparisons. We further examine the utility of the model by injuring either transgenic mice with lineage tracing for platelet-derived growth factor receptor alpha (Pdgfra) or beta (Pdgfrb). While not present before injury, both Pdgfra and Pdgfrb reporter+ cells migrate into sites of growth plate injury and participate in bony bar formation. In sum, this model offers a standardized, reproducible, and validated approach to quantitatively study growth plate injury mechanisms, facilitating the use of transgenic animal models or the development of new therapeutic strategies in pediatric orthopaedics.