Meniscal cysts are a relatively uncommon occurrence that may result in pain and disability in the knee. It is widely believed that meniscal cysts are secondary to fluid extrusion from a meniscus tear. Typically, diagnosis of a meniscal cyst typically requires magnetic resonance imaging (MRI) to delineate the cyst and any associated injuries. With improvements in sonographic technology, ultrasound has emerged as a sensitive modality for detection of meniscal cysts. We present a patient with a contraindication to MRI who was diagnosed with a lateral meniscal cyst by musculoskeletal ultrasound and treated with an ultrasound-guided lateral meniscal cyst aspiration and injection.
Meniscal cysts are a relatively uncommon occurrence that may result in pain and disability in the knee. The incidence of meniscal cysts estimated in a prior magnetic resonance imaging study was 4% [
Confirmation of the diagnosis of a meniscal cyst will usually require magnetic resonance imaging (MRI) due to its ability to delineate the cyst and evaluate any associated meniscal pathology. However, with the recent improvement in sonographic technology, ultrasound has emerged as a sensitive modality for detection of meniscal cysts [
A 26-year-old male with no significant past medical history presented to our clinic with a chief complaint of left lateral knee pain. On examination, the patient had a visible
Visible mass on lateral joint line on the knee.
Ultrasound image in the coronal plane demonstrating an anechoic meniscal cyst (arrow) superficial to the lateral meniscus.
After obtaining informed consent, the lateral meniscal cyst was visualized using a Sonosite M-Turbo with the “hockey puck” 13–8 Mhz ultrasound probe. 1% lidocaine was administered subcutaneously and a 19 G needle was inserted into the cyst under direct ultrasound guidance in the long axis (Figure
Ultrasound image in the coronal plane demonstrating aspiration of the meniscal cyst (arrow).
Ultrasound image in the coronal plane demonstrating resolution of the cyst immediately after aspiration and injection.
Meniscal cysts are a rare diagnosis, with an estimated incidence of 1–8% in prior studies [
The diagnosis of a meniscal cyst is usually established through a combination of a good patient history, clinical examination, and diagnostic imaging. Patients with a meniscal cyst will typically report symptoms of focal knee pain and swelling along the joint line. Due to its association with meniscal cysts, symptoms of a meniscus tear, such as popping, joint stiffness, and locking may also be present. On examination, patients with meniscal cysts may often present with a palpable mass along the joint line. Parameniscal cysts of the lateral meniscus are more commonly palpable compared to parameniscal cysts of the medial meniscus [
MRI Imaging is typically considered the “gold standard” for a suspected meniscal cyst due to its ability to delineate the cyst and assess the menisci [
The availability of high-frequency and high-resolution ultrasound machines has made it possible for sonographic detection of meniscal cysts. Rutten et al. [
High-resolution ultrasound has also allowed the possibility for image-guided aspiration of the meniscal cyst. Muddu et al. [
Our case is unique because it demonstrates the benefits of musculoskeletal ultrasound for diagnosis and treatment of a meniscal cyst when an MRI is contraindicated. Furthermore, the use of musculoskeletal ultrasound in the clinic on initial evaluation ensured efficient health care delivery, providing an accurate diagnosis and therapeutic plan on the same day without requiring a return trip for the patient to the clinic.
In conclusion, even though an MRI is the preferred modality for diagnosis of meniscal cysts, musculoskeletal ultrasound is a viable option for both diagnosis and treatment of this condition, especially in patients with contraindications to MRI. In addition, ultrasound-guided percutaneous aspiration and injection of painful meniscal cysts are a well-tolerated, simple, and effective procedure that may provide long-term symptomatic relief.
The author declares that there is no conflict of interests regarding the publication of this paper.