Have you noticed a mysterious lump on your wrist that seems to appear and disappear? It’s probably a synovial cyst, a benign but sometimes troublesome condition. Find out everything you need to know about this common condition and the treatment options available to make informed decisions about your health.
Definition and symptoms of synovial cysts
A synovial cyst, also known as a joint cyst, is a benign swelling that develops as a pocket filled with a viscous gelatinous fluid. This mass usually forms near a joint, most commonly in the wrist.
The most common locations are :
- The dorsal (back) side of the wrist, between the extensor tendons
- Palmar surface (front) of the wrist, in the radial pulse groove
- At the base of a finger
- More rarely on the foot or ankle
These synovial cysts predominantly affect young adults between the ages of 20 and 40, although they can sometimes be diagnosed in children or older people. Statistically, they account for around 60% of soft-tissue masses of the hand and wrist.
Synovial cysts are mainly manifested by :
- A visible swelling under the skin, round and well-defined.
- Firm but slightly elastic consistency
- Variable size, from a few millimetres to several centimetres
- Variations in volume depending on activity and stress on the joint
In the majority of cases, synovial cysts are asymptomatic, causing only cosmetic discomfort. However, some patients may experience :
- Pain in the affected joint, particularly during movement
- Reduced wrist or finger mobility
- A feeling of weakness in movement
It’s important to note that the intensity of symptoms does not necessarily correlate with the size of the cyst. A small cyst can be very painful if it compresses sensitive structures, while a large cyst can remain painless.
Diagnosis of synovial cysts
A medical consultation is recommended as soon as you notice a persistent lump in the wrist, especially if it :
- Gradually increases in volume
- Becomes painful
- Limits your daily movements
- Causes numbness in the hand or fingers
Precise diagnosis of a synovial cyst requires a thorough clinical examination. The doctor will assess the consistency of the mass, its mobility and the presence of inflammatory signs.
Ultrasound is the gold standard for confirming the diagnosis of a synovial cyst. This non-invasive examination makes it possible to :
- Confirm the cystic nature of the mass
- Precise sizing
- Visualize relationships with adjacent structures (tendons, nerves, vessels)
- Assessing peripheral vascularity
In more complex cases, an MRI scan may be prescribed to clarify the local anatomy and detect any associated pathologies.
Early diagnosis helps rule out other, potentially more serious diagnoses (such as soft tissue tumors) and optimize therapeutic management.
Causes and formation of synovial cysts
Synovial cysts arise from degeneration or weakness of the joint capsule. A joint is normally enclosed by this capsule, which is covered by the synovial membrane that secretes the joint fluid needed for lubrication.
If intra-articular pressures increase, the fluid may find a point of weakness in the capsule, which then deforms to form the cyst pocket. This is why the volume of the cyst can vary considerably over the course of a day, depending on the pressures exerted on the joint.
The exact causes triggering the appearance of a synovial cyst are not yet fully understood. It may occur :
- Spontaneously, for no apparent reason (most frequent case)
- Following trauma (about 10% of cases)
- Due to overuse of the joint
- Aging joints (osteoarthritis)
- Linked to chronic inflammation of the synovial membrane
An important fact to know: around 25% of synovial cysts regress spontaneously within 6 months of their appearance, without any treatment.
Possible treatments for synovial cysts
Simple monitoring and conservative treatment
Given the benign nature of synovial cysts, simple monitoring is often the preferred option, especially when the cyst causes little or no pain.
For mildly symptomatic cysts, a few simple but effective principles can be applied:
- Temporary restriction of activities involving intensive wrist use
- Occasional application of ice to reduce inflammation
- Wearing a night rest splint to limit unconscious movements
- Non-steroidal anti-inflammatory drugs for persistent pain
These conservative measures are generally sufficient to control symptoms and avoid more invasive procedures.
Medical treatment of synovial cysts
For symptomatic cysts, several non-surgical approaches can be considered:
Puncture aspiration This technique involves emptying the cyst using a large-gauge needle. It is effective in around 50% of patients, but has a high recurrence rate (up to 70% in the following months).
Corticosteroid infiltration Treatment: Often performed after a puncture, it can reduce inflammation and delay recurrence. However, its long-term efficacy remains limited.
Analgesics and anti-inflammatories To relieve pain associated with cysts.
These medical treatments can be repeated if necessary, but their effectiveness generally diminishes after several attempts.
Surgical treatment of synovial cysts
Surgical removal is indicated when the cyst is painful, functionally troublesome or recurs after medical treatment. Two approaches are possible:
Conventional surgery :
- Performed under local anaesthetic in most cases
- Cutaneous incision of a few centimetres centred on the swelling
- Complete removal of the cyst with its implantation pedicle
- Recurrence rate after surgery: around 20-30% according to recent studies
Arthroscopic surgery :
- Minimally invasive technique using small incisions
- Direct joint visualization
- Generally faster recovery
- Less visible scars
- Recurrence rate comparable to conventional surgery
Minimally invasive techniques are preferred whenever possible, to reduce post-operative complications and speed recovery.
Post-operative recovery
After synovial cyst surgery, you can expect :
- Moderate pain for a few weeks, especially when mobilizing the wrist
- Possible temporary limitation of joint mobility
- Scar dressing care
- Removal of non-absorbable sutures within two weeks of surgery
To optimize your recovery, there are a few simple but essential steps you can take on a daily basis:
- Regular application of ice (15-20 minutes, 3-4 times a day) to reduce inflammation
- Strict adherence to the prescribed rest period without prematurely testing your wrist.
- Keep wrist slightly elevated to reduce swelling, especially at rest
- Strict adherence to medical advice regarding splint use and authorized activities
Post-operative immobilization is not systematic, but a semi-rigid splint may be prescribed for a few weeks’ comfort. Physiotherapy is generally not necessary, as joint flexibility is regained through self-education movements.
The resumption of activities is gradual:
- Return to work: varies according to your profession and activities (generally 1 to 3 weeks).
- Resumption of sporting activities: generally after one month
- Full recovery: approximately 6 to 8 weeks
Possible complications
As with any surgical procedure, removal of a synovial cyst entails certain risks:
Immediate complications :
- Infection: Superficial at the scar (1-2% of cases) or, more rarely, deep into the joint.
- Hematoma: Usually limited but may require puncture
- Nerve damage: temporary sensory disturbances around incisions (5-10% of cases)
Late complications :
- Joint stiffness: sometimes associated with algoneurodystrophy (complex regional pain syndrome)
- Hypertrophic scar or keloid
- Residual pain
- Recurrence: Possible in 20-30% of cases despite complete exeresis
Patience remains your best ally in this healing process, which takes time but guarantees optimum results when all the steps are followed.
Prevention and practical advice
There are no specific preventive measures against the appearance of synovial cysts. However, a few practical tips may help:
- Avoid excessive repetitive wrist movements
- Adopt good ergonomics for prolonged computer use
- Seek prompt medical attention if a lump appears on the wrist
- Do not try to rupture the cyst by hitting it with a hard object, as this may cause local lesions with no lasting benefit.
- Regular exercises to strengthen wrist and forearm muscles
For sportsmen and women and professionals whose activities place intensive demands on the wrists, regular periods of rest and the use of suitable equipment (wrist guards, ergonomic gloves) can limit the risk of synovial cysts appearing or recurring.
Frequently asked questions about synovial cysts
Is a synovial cyst cancerous? No, synovial cysts are benign lesions with no risk of malignant transformation.
Can a synovial cyst be removed without surgery? Yes, around 25% of synovial cysts disappear spontaneously within 6 months. Puncture-aspiration can also be effective in certain cases.
Can synovial cysts recur after surgery? Yes, the recurrence rate after surgery is around 20-30% according to recent studies.
Can a synovial cyst appear anywhere other than on the wrist? Yes, although the wrist is the most common location, synovial cysts can appear near other joints such as the fingers, ankle or foot.
When should you be concerned about a synovial cyst? Seek prompt medical attention if your cyst becomes painful, rapidly enlarges, causes numbness or restricts movement.
Can children develop synovial cysts? Yes, although less common than in adults, synovial cysts can affect children and adolescents.
Conclusion
Synovial cysts are a benign condition which, in the majority of cases, require no special treatment. Around a quarter of cysts disappear spontaneously within a few months. However, if you experience pain or functional discomfort, don’t hesitate to consult a specialist, who will suggest the most appropriate therapeutic solution for your situation.
Never ignore a persistent lump in the wrist, however apparently benign. Seek medical advice as soon as possible, follow the prescribed treatment scrupulously and allow yourself the time you need to recover. These precautions will enable you to regain full, pain-free use of your wrist, essential for so many daily activities.