Synovial cyst

Definition

Synovial cyst may develop suddenly or progressively over several months, and is sometimes characterised by periods of disappearance.

The cyst may be painless or, on the contrary, involve pain which is local or shooting over the hand or up towards the elbow.

The synovial cyst is completely benign and in general is only a source of discomfort in terms of aesthetics or due to the compression it exerts in relation to the other anatomical structures (tendons, nerves, vessels).

Diagnosis

Synovial cysts occurring on the wrist are usually linked to the joint, often initially connected to a ligament lesion, resulting in irritation of the joint membrane, then a blister filled with a jelly-like secretion.

When they appear on the fingers, the cysts are often connected to the sheath of the flexor tendon.

Diagnosis is made on consultation. Further examinations are usually of little help other than a simple X-ray assessment. More in-depth examinations will be carried out, notably on the wrist if a more serious subjacent lesion is suspected.

Treatment

Treatment is not always necessary. If the cyst is not causing pain and is well-tolerated it may be left alone. Personally I do not recommend crushing the cyst because this often proves to be a painful, yet inefficient solution.

It may be proposed to puncture or lance the cyst with a needle in conjunction with a corticoid injection but the rate of recurrence with this technique is very high.

With a cyst causing functional or aesthetic discomfort, and when the cyst has been present for over 4 months, surgery may be recommended.

The procedure involves removing the whole cyst, and treating the lesions responsible for the condition as best as possible. The technique is realised by making a small incision on the fingers. Where the wrist is concerned, arthroscopy may be used.

Surgical procedure

• Length of hospital stay: outpatient (no overnight stay)
• Anaesthetic: regional
• A tourniquet is placed at the root of the limb to prevent bleeding

Arthroscopic surgery:

This technique is applied to cysts of the wrist. It involves inserting a camera and miniature instruments into the joint, usually by means of 2 small incisions, so as to remove the whole cyst from the inside and detect the possible presence of ligament-related lesions which could be responsible for the it. These lesions are then treated as part of the procedure.

The advantage of this method compared with open surgery concerns aesthetics (minimal incision), and allows for more rapid functional recovery.

I usually prescribe an immobilisation period with a splint for ten to fifteen days and a few physiotherapy sessions may be necessary afterwards.

Open surgery :

When the cyst on the wrist is difficult to access via endoscopy, an incision may be required in order to proceed to the ablation process.

On the fingers, a small incision enables the surgeon to remove cysts stemming from the digital canal

After-surgery care

A splint is put in place for 10 to 15 days, leaving the fingers free.

A few physiotherapy sessions may be necessary afterwards.

The patient’s work is to be stopped depending on profession, and sports activities using the wrist may be resumed after approximately one month.

Possible complications

• Recurrence is the most frequent complication, in 5 to 10% of cases.
• The initial swelling of the wrist or finger, and there may be discomfort which limits function for a few weeks. – A small cyst may appear for a few weeks at the orifices used for insertion during the endoscopy procedure, but they disappear in general.
• Infections are always possible, but rare.
• Healing may sometimes be painful with an unsightly scar on the wrist, depending on the individual case.
• Algoneurodystrophy may develop, as with all operations, and include extensive swelling, stiffness and pain in the hand which can last several months. It is not possible to predict its occurrence or the stiffness left as an after effect and pain is therefore a possibility.