1. What are the primary findings?
The key finding is the large suprapatellar effusion seen on the lateral view. The superior pole on the lateral view and the medial facet on the sunrise view also appear to have lost their cortical margins which suggests erosive changes. There is no evidence of fracture, crystalline deposition disease, or neoplasm which may be associated with an effusion. A soft tissue injury cannot be ruled out by radiography but may be ruled in/out by history.
2. List your differential diagnosis.
The findings suggest an inflammatory process. These would include inflammatory arthritis such as rheumatoid versus septic arthritis. In the appropriate clinical setting the effusion may be due to a soft tissue injury. Crystalline joint deposition disease is also considered less likely.
Good history taking may be extremely useful to arriving at the diagnosis. In this case, the patient is status post recent arthroscopy. The correct diagnosis in this case the is septic arthritis.
Septic arthritis is a joint infection which may be bacterial, viral, or fungal in nature. Clinically patients may present with fever and chills as well as pain, redness, swelling, and stiffness in the joint. The joint may also be warm to the touch.
Patients that are diabetic, immunosuppressed, IV drug abusers, or have a history of prior joint surgery or penetrating injury, sickle cell disease, alcoholism, or immune disease are at an increased risk for developing septic arthritis. In this particular case the patient was status post recent arthroscopy.
Lab tests such as cultures of joint aspirate, as well as elevated white counts, sedimentation rate, and C-reactive protein may be elevated in blood lab evaluations.
3. What is the appropriate treatment?
Septic arthritis is generally treated with broad spectrum antibiotics until the joint fluid can be aspirated and cultured to determine the best course of treatment. Joint aspiration may be needed on a daily basis. If infection persists, more aggressive procedures such as arthroscopy to remove the synovium or open surgery may be needed.
The following are key images from the patient's MRI scan:
The key finding is the large suprapatellar effusion seen on the lateral view. The superior pole on the lateral view and the medial facet on the sunrise view also appear to have lost their cortical margins which suggests erosive changes. There is no evidence of fracture, crystalline deposition disease, or neoplasm which may be associated with an effusion. A soft tissue injury cannot be ruled out by radiography but may be ruled in/out by history.
2. List your differential diagnosis.
The findings suggest an inflammatory process. These would include inflammatory arthritis such as rheumatoid versus septic arthritis. In the appropriate clinical setting the effusion may be due to a soft tissue injury. Crystalline joint deposition disease is also considered less likely.
Good history taking may be extremely useful to arriving at the diagnosis. In this case, the patient is status post recent arthroscopy. The correct diagnosis in this case the is septic arthritis.
Septic arthritis is a joint infection which may be bacterial, viral, or fungal in nature. Clinically patients may present with fever and chills as well as pain, redness, swelling, and stiffness in the joint. The joint may also be warm to the touch.
Patients that are diabetic, immunosuppressed, IV drug abusers, or have a history of prior joint surgery or penetrating injury, sickle cell disease, alcoholism, or immune disease are at an increased risk for developing septic arthritis. In this particular case the patient was status post recent arthroscopy.
Lab tests such as cultures of joint aspirate, as well as elevated white counts, sedimentation rate, and C-reactive protein may be elevated in blood lab evaluations.
3. What is the appropriate treatment?
Septic arthritis is generally treated with broad spectrum antibiotics until the joint fluid can be aspirated and cultured to determine the best course of treatment. Joint aspiration may be needed on a daily basis. If infection persists, more aggressive procedures such as arthroscopy to remove the synovium or open surgery may be needed.
The following are key images from the patient's MRI scan:
The post contrast images show the effusion with the marked enhancement of the synovium, the classic appearance of joint synovitis. There is also strong enhancement within Hoffa's fat pad. The sagittal T2 images demonstrates fluid leak through the the arthroscopy track within the anterolateral soft tissue.