Differential Diagnosis for Knee Pain in a 12-year-old Male
Single Most Likely Diagnosis
- Osgood-Schlatter Disease: This condition is a common cause of knee pain in adolescents, particularly during growth spurts. It is characterized by inflammation of the patellar tendon at its insertion on the tibial tubercle, leading to pain and swelling just below the knee.
Other Likely Diagnoses
- Patellofemoral Pain Syndrome: This condition is characterized by pain around or behind the patella, often related to activities that put stress on the knee, such as jumping, running, or climbing stairs. It's common in adolescents and can be due to various factors, including overuse, misalignment of the patella, or muscle imbalances.
- Medial Collateral Ligament (MCL) Sprain or Strain: Injury to the MCL can occur from a direct blow to the knee or a sudden twisting motion. It's a common injury in sports and can cause pain on the inner aspect of the knee.
- Meniscal Injury: Tears in the meniscus, the cartilage that cushions the joint, can cause knee pain, especially with twisting motions or deep knee bending. While more common in adults, meniscal injuries can also occur in adolescents, particularly those involved in sports.
Do Not Miss Diagnoses
- Septic Arthritis: Although less common, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. It can present with sudden onset of severe knee pain, swelling, redness, and warmth, often accompanied by systemic symptoms like fever.
- Osteosarcoma or Other Bone Tumors: While rare, bone tumors can cause knee pain in adolescents. These conditions are critical to diagnose early due to their potential for serious morbidity and mortality.
- Slipped Capital Femoral Epiphysis (SCFE): This condition involves the displacement of the femoral head from the femoral neck through the physeal plate. It can cause knee pain (referred pain) and is more common in obese adolescents. Early diagnosis is crucial to prevent long-term damage.
Rare Diagnoses
- Kohler Disease: A rare condition characterized by avascular necrosis of the navicular bone, which can cause knee pain due to referred pain mechanisms.
- Sinding-Larsen-Johansson Syndrome: Similar to Osgood-Schlatter disease but involves the patellar tendon at its origin on the inferior pole of the patella, causing pain at the front of the knee.
- Discoid Meniscus: A congenital anomaly of the meniscus that can cause knee pain, locking, or snapping sensations in the knee. It's rare and often diagnosed incidentally or after a meniscal tear.