Differential Diagnosis for Left Knee Pain
Single Most Likely Diagnosis
- Meniscal Tear: The patient's sharp pain when bending, flexing, and putting pressure on the knee, especially after a traumatic injury like skateboarding, is highly suggestive of a meniscal tear. The absence of swelling and redness does not rule out this diagnosis, as these symptoms may not always be present immediately after the injury.
Other Likely Diagnoses
- Ligament Sprain: The mechanism of injury and the symptoms described could also be consistent with a ligament sprain, particularly if the patient experienced a twisting motion while skateboarding.
- Contusion or Bone Bruise: A direct blow to the knee during the fall could result in a contusion or bone bruise, leading to pain, especially with pressure and movement.
- Patellofemoral Pain Syndrome: Although less likely given the acute onset, patellofemoral pain syndrome could be considered if the pain is primarily around the patella and is exacerbated by activities that increase patellofemoral stress, like bending and flexing.
Do Not Miss Diagnoses
- Fracture: Although the patient does not report swelling or redness, it is crucial not to miss a fracture, especially an occult fracture that might not be immediately apparent. A fracture could lead to significant morbidity if not promptly diagnosed and treated.
- Septic Arthritis: Although less likely without signs of infection like redness, warmth, or swelling, septic arthritis is a medical emergency that requires immediate attention. The absence of these signs does not rule out the diagnosis, especially in immunocompromised patients or those with a history of joint problems.
- Osteonecrosis: If the patient has a history of steroid use, alcohol abuse, or other risk factors, osteonecrosis could be a consideration, although it typically presents with more chronic symptoms.
Rare Diagnoses
- Osteochondritis Dissecans: This condition involves a fragment of cartilage and bone becoming detached, often due to trauma. It is less common and might present with locking or catching sensations in addition to pain.
- Plica Syndrome: Irritation of the synovial folds within the knee joint could cause pain, especially with certain movements, but this is a less common diagnosis and usually considered after other causes have been ruled out.