• Definition: The most frequent space-consuming lesion of the hand. It is a fluid-filled cyst that originates from joints or tendon sheaths. This mass is bounded on the outside by a membrane and filled with a gelatinous fluid, which is formed by the joint capsule or tendon sheath.
  Overview: The joints and flexor tendon sheaths are lined with a lubricant-producing membrane. This membrane can form a bulge that remains connected to the joint or tendon sheath. The volume of this sac filled with gelatinous fluid can change. The causes are e.g. arthrosis, overstrain or rheumatic diseases – more rarely, an accident. Common sites of origin include the wrist, distal interphalangeal joints (joint closest to the nail), and the flexor tendon sheath.
  Symptoms: These range from asymptomatic to cosmetically disruptive through to movement-related pain. As there is no correlation between the size of the ganglion and the pain the patient feels, even non-palpable ganglia can be very painful. A ganglion that originates from the distal interphalangeal joint and compresses the nail can lead to incorrect nail growth.
• Diagnosis: The medical history and clinical examination are often characteristic. Very small “occult” ganglia may not be palpable from the outside. Depending on location and severity, the clinical examination is supplemented by conventional radiography, sonography or MRT.
• Differential diagnoses: Tendinitis, arthrosis, rheumatic diseases and other less common hand tumours.
• Therapy: A ganglion is harmless and does not necessarily require therapy. If the ganglion is bothersome, there are several therapeutic concepts. The least invasive procedures are ganglion puncture and the cortisone infiltration, used especially for wrist ganglia, in which part of the fluid is aspirated and cortisone is injected. The wrist ganglion can also be removed endoscopically: two to four small skin incisions are made on the back of the wrist and the wrist capsule on the back is removed under endoscopic control. This technique is particularly advantageous for occult or non-palpable ganglia. Another option is the open surgical removal of the ganglion. Here a longer skin incision is made to expose the ganglion in the subcutaneous fatty tissue, and the stalk – i.e. the connection to the joint or tendon sheath – is laid free and removed in its entirety. If it is a ganglion of a joint with discrete arthrosis, a conchial spur (osteophyte) near the ganglion is often also removed to reduce the risk of recurrence. If the arthrosis of a distal interphalangeal joint is advanced, the option of surgical joint stiffening will be discussed before the operation.
• Post-operative care: Following surgery for wrist ganglia the wrist is immobilised for a few days, though not following tendon sheath ganglia. Following the surgery you can again safely go ahead and move your hand freely. Depending on the type of work, you can again carry out physically demanding work with your hand from four to six weeks after wrist ganglia removal. Ergotherapeutic post-operative care is particularly effective following wrist ganglion removal.
• Prognosis: It is a benign tumour. Infiltration and cortisone injection is successful in about half of all patients. The chances of success are even better after a second infiltration, which may be necessary. The risk of recurrence is only about 20% in this case. Although surgery is invasive and thus requires more complicated follow-up care, it carries only a 5% risk of recurrence. To avoid surgery, injection is often initially recommended. If a ganglion originates from a joint, the connection to the joint capsule must also be surgically removed to reduce the risk of recurrence. The joint capsule will heal and form a scar. Ergotherapeutic movement exercises are carried out as part of standard post-operative care to ensure that hand mobility is restricted as little as possible. There may, however, be a slight deterioration of mobility. If a joint ganglion of a slightly worn joint is removed, joint pain may worsen slightly after the operation. This standard operation has generally good results but sometimes requires lengthy occupational therapeutic aftercare to improve hand mobility.