Differential Diagnosis for Left Knee Pain and Swelling
Single Most Likely Diagnosis
- Osteoarthritis (OA): The presence of severe medial compartment joint space loss, tricompartmental osteophytes, and quadriceps insertion enthesophyte on the left knee X-ray, along with the patient's complaint of knee pain and swelling, strongly suggests OA as the primary diagnosis. The absence of systemic symptoms (denies SOB) and unremarkable CBC and CMP further support this diagnosis.
Other Likely Diagnoses
- Meniscal Tear or Ligamentous Injury: Although the X-ray does not show an acute fracture, a meniscal tear or ligamentous injury could still be present, causing pain and swelling, especially if the patient has a history of trauma or overuse.
- Crystal Arthropathy (e.g., Gout or Pseudogout): The presence of joint space loss and osteophytes could also be seen in crystal arthropathies, although the absence of systemic symptoms and unremarkable lab results make this less likely.
- Inflammatory Arthritis (e.g., Rheumatoid Arthritis): Although less likely given the unremarkable lab results, inflammatory arthritis could still be a consideration, especially if the patient has a history of autoimmune disorders.
Do Not Miss Diagnoses
- Deep Vein Thrombosis (DVT): Although the Venus duplex is negative, it is essential to consider DVT in any patient with unilateral leg swelling, especially if there are risk factors for DVT (e.g., recent surgery, immobilization, or cancer). The patient's recent total knee arthroplasty on the right knee increases the risk of DVT.
- Septic Arthritis: Although the patient denies systemic symptoms, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. The absence of a large effusion on the X-ray does not rule out septic arthritis.
- Osteonecrosis: The patient's history of total knee arthroplasty on the right knee may increase the risk of osteonecrosis, especially if there is a history of steroid use or other risk factors.
Rare Diagnoses
- Hemochromatosis: This genetic disorder can cause OA-like symptoms, as well as other systemic symptoms. Although rare, it is essential to consider in patients with unexplained OA or other systemic symptoms.
- Wilson's Disease: This rare genetic disorder can cause OA-like symptoms, as well as neurological and psychiatric symptoms. Although unlikely, it is essential to consider in patients with unexplained OA or other systemic symptoms.