Subchondral Bone Cysts

We developed a finite element model to investigate subchondral bone cysts that develop in the medial femoral condyle. We used this model to determine if a transcondylar lag screw is the best option to treat them. This video was made for this competition! In summary, we found that high shear stress may explain initial cyst development and subsequent enlargement of the void. The defect will rarely heal with rest and current debridement treatments. We believe this is because the bone surrounding the hole is not receiving enough stimulus for growth. Due to the pain the defect causes, the affected joint is substantially unloaded. No fracture callous is ever formed, as does with regular bone fractures, so rest is not sufficient for growth. A transcondylar screw treatment developed by a veterinary surgeon has shown high success and full radiographic healing. We believe this is because the screw is able to generate compression in the surrounding bone and provide additional stimulus for bone formation. We were able to model this surgical treatment and quantify its efficacy, as well other variations of the surgery. Our model has been validated against these clinical trials, and we are optimistic about the surgery and what more the model can tell us!