PRESENTATION OUTLINE
Definition
- also known as a popliteal cyst
- a baker's cyst is located behind the knee as a result of accumulating synovial fluid from a weakened joint capsule
- commonly caused by rheumatoid arthritis
Patient Presentation
- asymptomatic
- may have tenderness behind the knee
- labs: RF present in blood, increased ESR, hyperuricemia
Scanning Technique
- linear sequential transducer
- patient is supine with leg bent at the knee, angled and resting on the bed
- transverse and longitudinal scan planes
- measurements and color to be included in the scan
- pitfalls: patient habitus, patient discomfort, location of cyst
This middle aged female patient presented with a large mass in the left popliteal region which was seen on extension of the knee joint. Ultrasound images of the popliteal fossa show a large cystic mass of 5.7 x 2.8 cms. with few echogenic particles within a primarily clear fluid. The cyst is in close relation to the left knee joint; however, these images did not reveal clear communication with the synovial space of the knee joint. The popliteal artery was visualized on Color Doppler imaging, and was clearly separate from the cyst, ruling out the possibility of aneurysm of this vessel. Final diagnosis: Baker cyst (also called Baker's cyst).
Transverse ultrasonographic image of the knee in a patient who had recent arthroscopy shows a complex, cystic mass (arrow) in the medial aspect of popliteal fossa. The mass communicates with the knee joint (arrowhead), which is consistent with a Baker cyst.
Differential Diagnosis
- synovial sarcoma: malignant tumor of soft tissue around large joints, especially the knee; slow-growing; most often in young adults; hypoechoic mass on ultrasound
- popliteal artery aneurysm: most common peripheral aneurysm; more evident in older males; bilateral; associated with AAAs
Other Imaging Modalities
MRI:helps to locate mass using axial plane
Treatment
- icepacks, resting, compression bandages
- aspiration, surgical excision
- physical therapy
Definition
- most commonly injured ankle tendon
- connects the calf muscle to the posterior heel
- tendonitis: inflammation of the achilles tendon
- rupture: tear of the achilles tendon
Patient Presentation
- most commonly posterior ankle pain
- tendonitis: pain, swelling, fever
- rupture: significant pain, swelling, edema
- Thompson Test: see if a complete or partial tear
Scanning Technique
- linear sequential transducer
- longitudinal and transverse imaging planes
- evaluate the entire tendon for tendonitis or rupture
- right and left scanned for comparison
- patient is prone with feet hanging off bed
- pitfalls: superficial location, patient habitus, patient discomfort
This longitudinal scan shows a significantly enlarged achilles tendon in the right frame with a normal sized tendon on the left
This patient had severe pain in the lower calf. Ultrasound examination of the tendo-achilles showed a full thickness tear of the Achilles tendon. This is seen as the linear anechoic area extending through the tendon (long section ultrasound images of Achilles tendon).
Differential Diagnosis
- ruptured baker's cyst: accumulated fluid between deep fascia and achilles tendon; appers as anechoic fluid containing echoes in this location
- retrocalcaneal bursitis: inflammation of bursa located posterior to the achilles tendon; ultrasound appearance of well-defined, anechoic fluid posterior to achilles tendon
Other Imaging Modalities
- MRI: if diagnosis is unclear on ultrasound, MRI may show an increased signal within the achilles
Treatment
- tendonitis: RICE, medication, physical therapy, surgery
- rupture: cast, surgery, rehabilitation