Differential Diagnosis for Left Knee Pain
Single Most Likely Diagnosis
- Osteoarthritis (OA): Given the patient's age (63 years), the location of the pain (medial knee), and the exacerbating factor (activity), OA is a highly likely diagnosis. The pain scale of 0/10 at rest and 6/10 with activity also supports this diagnosis, as OA pain typically worsens with weight-bearing activities.
Other Likely Diagnoses
- Meniscal Tear: The medial knee pain and exacerbation with activity could also suggest a meniscal tear, especially if the patient has a history of trauma or twisting injury.
- Ligament Sprain: A sprain of the medial collateral ligament (MCL) could cause medial knee pain, especially if the patient has a history of trauma or valgus stress to the knee.
- Bursitis: Inflammation of the medial knee bursae (e.g., pes anserine bursitis) could cause pain and swelling in the medial knee, especially with activity.
Do Not Miss Diagnoses
- Septic Arthritis: Although the patient denies fever, chills, or redness, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. A high index of suspicion is necessary, especially in older adults or those with underlying medical conditions.
- Osteonecrosis: Osteonecrosis of the femoral condyle or tibial plateau could cause medial knee pain, especially if the patient has a history of corticosteroid use, trauma, or other risk factors.
- Tumor: A bone or soft tissue tumor (e.g., osteosarcoma, synovial sarcoma) could cause medial knee pain, although this is less likely given the patient's age and lack of other symptoms (e.g., night pain, weight loss).
Rare Diagnoses
- Pellegrini-Stieda Syndrome: This rare condition involves calcification of the MCL and could cause medial knee pain, especially with activity.
- Medial Knee Compartment Syndrome: This rare condition involves increased pressure within the medial knee compartment and could cause pain, swelling, and weakness in the medial knee.