Differential Diagnosis for a 25-year-old Morbidly Obese Female with Posterior Knee Pain
- Single most likely diagnosis:
- Muscle strain or contusion: Given the patient's history of a recent slip and possible twist or hit to the knee, a muscle strain or contusion is the most likely diagnosis. The posterior knee pain and stiffness with ambulation are consistent with this diagnosis.
- Other Likely diagnoses:
- Ligamentous sprain: A ligamentous sprain, particularly to the posterior cruciate ligament (PCL) or medial collateral ligament (MCL), is possible given the mechanism of injury and the patient's symptoms.
- Meniscal tear: A meniscal tear is also a possible diagnosis, as the patient's symptoms of posterior knee pain and stiffness with ambulation could be consistent with a meniscal injury.
- Bursitis: Prepatellar or pes anserine bursitis could be considered, especially in a morbidly obese patient, as these conditions can cause knee pain and stiffness.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Popliteal artery injury: Although unlikely, a popliteal artery injury is a potentially life-threatening condition that requires prompt diagnosis and treatment. The patient's symptoms of posterior knee pain and stiffness could be consistent with a vascular injury.
- Deep vein thrombosis (DVT): Given the patient's morbid obesity and recent trauma, DVT is a possible diagnosis that should not be missed, as it can be life-threatening if left untreated.
- Osteonecrosis: Although less likely, osteonecrosis of the knee could be considered, especially if the patient has a history of steroid use or other risk factors.
- Rare diagnoses:
- Tibial plateau fracture: A tibial plateau fracture is a rare but possible diagnosis, especially if the patient had a high-energy trauma or has osteoporosis.
- Gastrocnemius or popliteus tendon rupture: Rupture of the gastrocnemius or popliteus tendon is a rare injury that could cause posterior knee pain and stiffness.