Synovial cyst of the foot: definition, surgery and treatment.
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The synovial cyst of the foot is a benign lesion, relatively common. This nodular formation, although generally not dangerous and painless, can cause discomfort and may then require appropriate treatment.
Definition and explanations about the synovial cyst
A synovial cyst is a benign, nodular, fluid-filled formation that generally develops at the level of a joint capsule or a tendon sheath. It is a sac filled with a viscous and transparent fluid, similar to gel, which usually comes from synovial fluid, the fluid that lubricates our joints and allows the tendons to glide within their sheath.
How does a synovial cyst form?
A joint is enclosed by the articular capsule, which is itself covered by the synovial membrane. The synovial membrane secretes joint fluid, allowing the lubrication of the joint and the hydration of the articular cartilage.
When intra-articular pressure increases, the fluid pressure can find a weak spot in the capsule, which tends to deform and form the cyst sac. As long as the joint pressure remains high, the fluid fills the sac, forming the cyst. When the joint pressure decreases, the cyst can drain back into the joint. This is why synovial cysts can change in size and location over the course of the same day.
The formation of a synovial cyst is often linked to trauma, an intra-articular injury, or osteoarthritis.
It is important to note that although the presence of a synovial cyst may cause discomfort or pain, especially when it is under pressure, it is a benign condition.
Symptoms and signs for identifying a synovial cyst of the foot
A synovial cyst of the foot can sometimes go unnoticed, but certain signs can help with its detection.
What are the symptoms of a synovial cyst?
The symptoms of a synovial cyst can vary depending on its size and location. You may notice a lump, mass, or nodule under the skin, more or less firm, often filled with fluid. This mass can be soft or firm to the touch. In some cases, the cyst can cause pain or discomfort, especially when it is compressed and close to a nerve or blood vessel. Pain is generally related to the cause of the cyst, such as an intra-articular injury.
How to identify a synovial cyst of the foot?
The identification of a synovial cyst can be done by palpating the foot or the ankle; it may also be spontaneously visible. Ankle cysts have specific characteristics that are important to know.
The diagnosis of a synovial cyst requires a clinical examination, radiological assessment, and additional imaging depending on the suspected origin of the cyst. Ultrasound or MRI are frequently requested for the analysis of a synovial cyst.
Synovial cyst treatments
To treat a synovial cyst, several treatment options may be considered. It is essential to emphasize that each case is unique and requires a personalized approach.
What treatments are available?
The treatment of a synovial cyst can be either non-surgical or surgical. The choice of method depends on the size, location of the cyst, and the patient's symptoms.
Non-surgical treatment includes aspiration of the synovial fluid combined with an injection of corticosteroids, along with a short period of foot immobilization.
Surgical treatment involves performing an excisional biopsy of the cyst, meaning the entire cyst wall is removed for analysis. Anatomopathological analysis is systematically performed in cases of surgical intervention requiring tissue removal.
Can a synovial cyst be treated without surgery?
Yes, a synovial cyst can be treated non-surgically. In fact, a synovial cyst may spontaneously and completely regress over time.
If the cyst is bothersome, it is possible to perform an ultrasound-guided aspiration of the cyst, combined with a cortisone injection.
Surgical procedure for synovial cyst of the foot
Synovial cyst surgery of the foot is a benign procedure, rarely performed as synovial cysts in the foot are generally not very symptomatic and tend to regress spontaneously.
As with any surgical procedure, the biopsy surgery for removal of a synovial cyst requires a preoperative consultation with a foot surgeon. A thorough clinical examination is necessary to determine the possible cause of the cyst, which may require intervention on the synovial cyst and its cause. A standard radiological assessment is systematically prescribed. Additional imaging will also be prescribed, such as an ultrasound or an MRI, depending on the size, location, and suspected cause of the cyst. A pre-anesthesia consultation will also be necessary before the surgical procedure.
The operation is performed under regional anesthesia, with a tourniquet placed at the ankle or at the root of the thigh depending on the planned surgical procedure. In the vast majority of cases, the procedure is performed on an outpatient basis, meaning the patient leaves the clinic the same day. During the surgical intervention, it is essential to remove the cyst capsule to reduce the risk of recurrence. The cyst capsule is always sent to pathology for analysis.
We use minimally invasive surgical techniques to biopsy and resect a synovial cyst. In the vast majority of cases, it is necessary to make an incision over the cyst, dissect the capsule without opening it, until a possible communication with a joint or a tendon sheath is found.
More rarely, treatment of the synovial cyst may be performed by arthroscopy, which allows the cause of the cyst to be treated and the cyst to be removed.
Synovial cyst surgery of the foot
Synovial cyst surgery of the foot is offered in case of unsuccessful medical treatment.
When is surgery necessary?
The need for surgical intervention is generally considered when the synovial cyst of the foot causes significant pain or difficulty wearing shoes. Additionally, if the cyst does not respond to non-surgical treatments, such as aspiration or corticosteroid injection, surgery may be proposed.
How does the surgery take place?
The synovial cyst operation is usually performed on an outpatient basis, with same-day discharge from the clinic. After local anesthesia, under tourniquet, we make an incision to access the cyst and remove it if possible without opening the cyst wall. The cyst is then sent for pathological analysis. The cause of the synovial cyst must always be investigated and, if necessary, treated during the same procedure.
Post-operative care and rehabilitation after treatment of a synovial cyst
During the procedure, a bandage is applied in a sterile manner for a period of three weeks, without changing it. A postoperative shoe is prescribed to accommodate the usually thick bandage.
At the three-week postoperative appointment, the bandage is removed, and the stitches have generally completely dissolved. Depending on the cause of the cyst, wearing the postoperative shoe may still be required.
How does rehabilitation take place?
Generally, surgical excision biopsy of a synovial cyst does not require any specific rehabilitation.
We have covered together the essential aspects of the synovial cyst of the foot, from its definition to its symptoms, including diagnostic methods and treatment options. It is a benign lesion that may require surgical intervention if it does not regress spontaneously or if it persists after medical treatment.