Differential Diagnosis for 53-year-old Male with Right Knee Pain
- Single most likely diagnosis:
- Prepatellar bursitis: This condition is likely given the patient's history of bumping his knee, the presence of a scab over the patella, and the location of the pain. Prepatellar bursitis, also known as housemaid's knee, is an inflammation of the bursa in front of the patella, often caused by direct trauma or repetitive friction.
- Other Likely diagnoses:
- Contusion or hematoma: The patient's recent trauma to the anterior knee could have resulted in a contusion or hematoma, which might explain the severe sharp pain, especially if it's localized to the lateral side where the trauma occurred.
- Patellar fracture: Although less common, a patellar fracture could be considered, especially given the mechanism of injury (bumping the anterior part of the knee) and the presence of severe sharp pain.
- Lateral meniscal tear: This could be a possibility if the patient experienced a twisting injury or if the bump caused a meniscal tear, leading to sharp pain on the lateral side of the knee.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Septic arthritis: Although the patient denies fever and the joint is not hot, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. It could be considered, especially if the patient has a compromised immune system or if there's any suspicion of infection.
- Osteonecrosis: This condition, also known as avascular necrosis, could be a concern if the patient has a history of steroid use, excessive alcohol consumption, or other risk factors. It's essential to consider osteonecrosis to prevent delayed diagnosis and potential collapse of the bone.
- Rare diagnoses:
- Patellofemoral pain syndrome: This condition typically presents with anterior knee pain, usually related to activities that put stress on the knee, like climbing stairs, squatting, or jumping. It might be less likely given the acute onset and trauma history but could be considered if other diagnoses are ruled out.
- Neuroma or nerve entrapment: If the patient has a history of trauma or surgery, a neuroma or nerve entrapment could be a rare cause of his symptoms, especially if the pain is sharp and localized to a specific area.