Differential Diagnosis for Probable Healing Fracture of the Patella

• Single most likely diagnosis
  • Osteochondral fracture: This is the most likely diagnosis given the location (lateral aspect of the patella) and the description of a probable healing fracture with incomplete bony bridging. Osteochondral fractures involve both the bone and the cartilage, which could explain the incomplete healing seen radiographically.
• Other Likely diagnoses
  • Stress fracture: Stress fractures are small cracks in the bone that can occur with repetitive stress or overuse. The patella is a common site for stress fractures, especially in athletes. The incomplete bony bridging could indicate a stress fracture that is in the process of healing.
  • Avulsion fracture: An avulsion fracture occurs when a fragment of bone is pulled away from the main mass of bone as a result of physical trauma. This could be a possibility if the fracture is located at the site of a tendon or ligament attachment on the patella.
• Do Not Miss diagnoses
  • Pathological fracture: A pathological fracture occurs when a bone breaks due to a pre-existing condition that has weakened the bone, such as a tumor or osteoporosis. Although less likely, missing a pathological fracture could have significant consequences for the patient's health and treatment.
  • Infection (osteomyelitis): Infection of the bone could present with similar radiographic findings, including incomplete bony bridging. This diagnosis is critical to rule out as it requires prompt antibiotic treatment and possibly surgical intervention.
• Rare diagnoses
  • Osteonecrosis: Osteonecrosis, or avascular necrosis, is a condition that occurs when there is a loss of blood to the bone. This could potentially cause a fracture-like appearance on radiographs, although it is less common in the patella compared to other bones like the femoral head.
  • Bone cyst: A bone cyst is a fluid-filled lesion that can occur in bones. Although rare, a bone cyst in the patella could potentially weaken the bone and lead to a fracture, which might appear as incomplete bony bridging on radiographs.