Differential Diagnosis for Right Knee Pain
The patient's symptoms of right knee pain, particularly after performing deep squats, radiating pain down the leg, and stiffness and swelling after activity, suggest several potential diagnoses. These can be categorized as follows:
Single Most Likely Diagnosis
- Iliotibial (IT) Band Syndrome: This condition is characterized by pain on the outside of the knee, which can radiate down the leg, and is often associated with activities that involve repetitive knee bending, such as hiking, gardening, or deep squats. The symptoms described, including the location of the pain and the exacerbation with specific activities, align closely with IT band syndrome.
Other Likely Diagnoses
- Patellofemoral Pain Syndrome (PFPS): This condition involves pain around or behind the patella (kneecap), often related to activities that put stress on the knee, like squatting. While the pain in PFPS is typically more anterior, the mechanism of injury and activity-related exacerbation could also suggest this diagnosis.
- Meniscal Tear: A tear in the cartilage of the knee can cause pain, stiffness, and swelling, especially after twisting or squatting injuries. The absence of locking or catching symptoms makes this less likely, but it remains a consideration given the acute onset after a specific activity.
- Tendinitis (e.g., Quadriceps or Patellar Tendinitis): Inflammation of the tendons around the knee can cause pain, stiffness, and swelling, particularly after activities that stress these tendons, such as deep squats.
Do Not Miss Diagnoses
- Deep Vein Thrombosis (DVT): Although less likely given the description of activity-related pain, DVT can cause leg pain and swelling. It's crucial to consider this diagnosis due to its potential severity and the need for urgent treatment.
- Osteonecrosis (Avascular Necrosis): This condition involves the death of bone tissue due to a lack of blood supply and can cause severe knee pain. It might not be the first consideration but should be kept in mind, especially if the pain is severe and persistent.
- Infection or Septic Arthritis: Although the patient denies fever or other systemic symptoms, an infectious process could cause severe knee pain, stiffness, and swelling. This diagnosis is critical to rule out due to its urgency and potential for serious complications.
Rare Diagnoses
- Plica Syndrome: This involves irritation of the synovial folds within the knee, which can cause pain and snapping sensations. It's less common and might be considered if other diagnoses are ruled out.
- Neurogenic Causes (e.g., Peripheral Nerve Entrapment): Although the patient denies numbness or tingling, certain neurogenic causes could potentially mimic some of the symptoms described, especially if the pain has a radicular component.