Differential Diagnosis for Left Knee Injury

The patient presents with a left knee injury, pain, and swelling that worsens with bending and movement after being kicked in the knee during a soccer game. The following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Medial Collateral Ligament (MCL) Sprain: The mechanism of injury, where the patient's knee was hit from the outside, causing it to twist inward, is classic for an MCL sprain. The location of the pain and the exacerbation of symptoms with movement and bending also support this diagnosis.

• Other Likely Diagnoses

  • Medial Meniscus Tear: The twisting mechanism and the presence of pain and swelling, especially with bending, could also indicate a meniscal tear. The intermittent throbbing pain is consistent with this diagnosis.
  • Contusion or Bruising: Given the direct trauma to the knee, a contusion or bruising of the soft tissues around the knee is possible, which could explain the pain and swelling.
  • Anterior Cruciate Ligament (ACL) Sprain: Although less likely than an MCL sprain given the mechanism, an ACL injury could occur with a significant twisting force, especially if there was a component of deceleration or landing from a jump.

• Do Not Miss Diagnoses

  • Fracture (e.g., Tibial Plateau Fracture): While less likely given the mechanism and absence of numbness or tingling, a fracture must be considered, especially if there was significant force involved in the kick. A fracture could lead to serious complications if not promptly diagnosed and treated.
  • Vascular Injury: Direct trauma to the knee could potentially injure the popliteal artery or vein, leading to serious complications, including limb ischemia. The absence of numbness, tingling, or coldness does not entirely rule out a vascular injury.
  • Neurological Injury (Peroneal Nerve Damage): Although the patient denies numbness or tingling, a peroneal nerve injury could occur from the trauma, especially if the kick was directly to the lateral aspect of the knee.

• Rare Diagnoses

  • Osteochondritis Dissecans: This condition involves a piece of cartilage and bone becoming detached from the surrounding bone, which could be precipitated by trauma. It is less common and typically presents in younger patients.
  • Patellar Dislocation: Although the patient does not report a sensation of the kneecap moving out of place, a patellar dislocation could occur from a direct blow to the knee, especially if there was a twisting component.