Differential Diagnosis for 16-year-old with Knee Pain after Landing and Hearing a Clicking Noise

• Single most likely diagnosis:
  • Patellar dislocation or subluxation: This condition is common in adolescents and can occur after a traumatic event like landing on the knee. The clicking noise heard could be indicative of the patella moving out of place.
• Other Likely diagnoses:
  • Meniscal tear: A meniscal tear can occur from a twisting injury or direct blow to the knee, which could explain the pain and clicking noise after landing on it.
  • Ligament sprain (MCL or LCL): Sprains to the medial or lateral collateral ligaments can happen from a direct blow or sudden twisting, leading to knee pain and instability.
  • Osteochondritis dissecans: This condition involves a piece of cartilage and bone becoming detached, often due to trauma, and can cause knee pain and a clicking sensation.
• Do Not Miss diagnoses:
  • Fracture (e.g., tibial plateau or patella): Although less common, fractures can occur from significant trauma and must be ruled out to avoid missing a potentially serious condition.
  • Septic arthritis: This is an infection within the joint space, which is a medical emergency. While less likely, it's crucial to consider, especially if there's significant swelling, redness, or fever.
• Rare diagnoses:
  • Osgood-Schlatter disease: Although more commonly associated with chronic knee pain in adolescents, it could potentially cause acute symptoms if there was a significant increase in activity or a traumatic event.
  • Discoid meniscus: A rare condition where the meniscus is thicker and more prone to tearing, which could explain the clicking noise and pain after a traumatic event.