Knee

Sonographic Diagnosis of Medial Meniscocapsular Separation of the Knee

Medial meniscocapsular separation (MCS) is an uncommon knee injury. No dedicated sonographic study on medial MCS has been reported thus far. This article retrospectively analyzes the sonogram of two patients with medial MCS confirmed by either magnetic resonance imaging (MRI) or surgery. Both patients are in their 30s with sports-related medial knee injuries. Sonograms of their medial knees displayed similar features of fluid collection between the medial meniscus and the deep portion of the medial collateral ligament (MCL), and an unsmooth outer surface of the meniscus. Meniscal tear and MCL injury were also found in both of these patients. Sonographic diagnostic criteria for the medial MCS are proposed based on the two patient cases. The differentiation of medial MCS from other cystic lesions in the medial parameniscal area is also discussed.

Ultrasound Imaging of the Deep Peroneal Nerve

Ultrasound is considered an excellent imaging modality to evaluate the nerves of the limbs. The deep peroneal nerve (DPN) is one of the terminal branches of the common peroneal nerve. The DPN may be affected by various disorders, which may be clinically challenging to show. This Pictorial Essay reviews the normal ultrasound anatomy of the DPN and presents disorders that may involve the nerve and its main branches along its course, from proximal to distal.

Sonography of Knee Effusion

Objective:

A review of the anatomy of the synovial recesses of the knee is important to better understand the different effusion presentations, update the diagnosis criteria of knee effusion based on the measured synovial recesses and discuss the differentiation of some effused recesses from other lesions around the knee.

Method:

This review focuses on the anatomy of the synovial recesses of the knee and classifies them into three groups (anterior, parameniscal, and posterior recesses), as well as provides an overview on the etiology of knee effusion, its sonographic detection, and diagnosis criteria.

Results:

Knee effusion is a very common pathological finding in sonography of the knee. The unique joint structure of the knee provides the possibility to host complex synovial recesses. Fluid in some of the synovial recesses is valuable for the diagnosis of knee effusion, while in certain situations, some recesses may impose diagnostic uncertainty. Knowledge of these synovial recesses is essential to avoid diagnostic pitfalls.

Conclusion:

This review provides an important discussion of the differentiation of some recesses effusions from other lesions around the knee.

Sonographic features of vaccination granulomas in children with delayed-type hypersensitivity to aluminum

In this article, we report the sonographic features of vaccination granulomas in three children sensitized to aluminum. Although the recognition of the vaccination granuloma relies on the clinical examination, misdiagnosis is frequent, leading to distressful procedures or prolonged antibiotic administration. In all our cases, sonography revealed a teardrop-shaped echogenic central structure, suggesting the deposition of aluminum crystals along the route of administration with consequent subcutaneous degenerative changes, and a surrounding hypoechoic cap, which reflects the changeable inflammatory reaction and the granuloma formation.

The Sonographic Spectrum of Baker Cysts

Baker cysts are the most common pathologic finding in the sonography of the popliteal fossa. They have a wide range of sonographic appearances. Some of them may need to be recognized and differentiated from other popliteal lesions. Therefore, familiarity with their different imaging appearances is useful for clinical practice. This review summarized different presentations of Baker cysts. They are described in several categories, organized according to their shape and formation: typical Baker cysts and their mild variations, atypical small Baker cysts, ʎ-shaped Baker cysts and their related variations, Baker cysts with extension into nearby muscles, and Baker cysts with complications. The related differentiations are included in each category. The pathogenesis of Baker cysts is also discussed.

Distension of the Medial Collateral Ligament Bursa of the Knee With Possible Bursitis

The bursitis of the medial collateral ligament (MCL) of the knee is the inflammatory distension of the bursa located between the superficial and deep portions of MCL. Five cases with sonographic findings of suspected MCL bursitis were reviewed. All five cases had fluid collection with distinct and smooth borders between the superficial and deep portions of the MCL. Two of them had the fluid adjacent to the tibia; two of them adjacent to the femur; and one of them spanning the joint. Four of the five patients without recognizable knee injury history and middle third meniscal tear excluded the possibility of injury-related fluid collection. Hence, MCL bursitis is the possible diagnosis. One young adult with a recent knee injury also had a tear in the meniscofemoral ligament of the deep portion of the MCL. The distension of the bursa was interrupted by and directly connected to the tear of the meniscofemoral ligament. Therefore, it is part of the injury but not bursitis. This report describes sonographic characteristics of MCL bursitis that may assist in the diagnosis and differentiate it from other medial knee conditions.

A Case Study of Baker Cysts With Intramuscular Extension into the Medial Head of the Gastrocnemius

Baker cysts are common pathological findings during sonography of the popliteal fossa. Although they can present as a typical, mild variant or have an atypical sonographic appearance, a common feature of them is that their expansion is usually limited in the intermuscular planes or spaces between muscles and knee capsule. Baker cysts extending into muscles are rare. Two cases of a Baker cyst with extension into the medial head of the gastrocnemius (MHG) are reported with sonographic findings. Both of the cases were discovered in females, who had anterior or bilateral knee pain and radiographic features of osteoarthritis. Knee effusion was identified sonographically in both of the patient cases. In the popliteal fossa, Baker cysts were found in both patients with intramuscular extension into the MHG. In the first case, a cystic penetration was noted into the MHG, near the neck of the cyst, having a cone shape and oriented toward the inferior aspect of the muscle. The second case had a cystic penetration into the MHG near the base of the cyst with a tube shape, along its long axis. The possible pathogenesis is discussed.