Differential Diagnosis for Left Knee Pain
Single Most Likely Diagnosis
- Meniscal Tear: The patient's symptoms of left knee pain after deep squats, posterior knee pain with downward radiation, and difficulty going in and out of a car are consistent with a meniscal tear. Meniscal tears are common in individuals who participate in activities that involve twisting, bending, or squatting.
Other Likely Diagnoses
- Baker's Cyst: The patient's complaint of posterior knee pain with downward radiation is suggestive of a Baker's cyst, which is a fluid-filled swelling that causes a bulge and a feeling of tightness behind the knee.
- Ligament Sprain: The patient's history of deep squats and difficulty going in and out of a car may indicate a ligament sprain, which can cause knee pain and stiffness.
- Tendinitis: The patient's symptoms of knee pain and stiffness, particularly after hiking, may be indicative of tendinitis, which is inflammation of the tendons.
Do Not Miss Diagnoses
- Deep Vein Thrombosis (DVT): Although less likely, DVT is a potentially life-threatening condition that can cause leg pain and swelling. It is essential to consider DVT in the differential diagnosis, especially if the patient has a history of recent immobility or other risk factors.
- Septic Arthritis: Septic arthritis is a medical emergency that requires prompt treatment. Although the patient's symptoms do not strongly suggest septic arthritis, it is crucial to consider this diagnosis, especially if the patient has a fever, redness, or swelling around the knee.
Rare Diagnoses
- Osteochondritis Dissecans: This is a rare condition that affects the joint cartilage and underlying bone, causing knee pain and stiffness.
- Pigmented Villonodular Synovitis (PVNS): This is a rare condition that causes knee pain, swelling, and stiffness due to inflammation of the synovial membrane.
- Tumor or Cyst: Although rare, it is essential to consider the possibility of a tumor or cyst in the knee, which can cause pain, stiffness, and limited mobility.