What is a Mucus cyst?
It is a fluid filled cyst, that occurs at the end finger joint (distal inter-phalangeal joint), overlying the bed of the nail. They arise from the joint itself and can cause grooving or splitting of the nail. They may be associated with osteoarthritis of the joint. The cysts can become quite large and the overlying skin becomes quite thin. They often discharge a clear jelly like fluid either spontaneously of if knocked. They can occasionally become infected.
What is the cause?
Although we don't know exactly what causes mucus cysts, we believe they are probably related to arthritis in the distal joint of the finger. The arthritis may cause a bone spur to develop which irritates the inner joint capsule and leads to the development of the mucus cyst.
Diagnosis can often be made from the clinical history (the account of events and symptoms from the patient) and the clinical examination. An X-ray may show some wear and tear in the joint.
Mucus cysts may disappear spontaneously, many will however recur. Surgery is indicated for pain, problems with use of the finger, if the cyst is frequently discharging or if the underlying nail becomes very deformed and irregular. I would recommend that you not try to puncture or aspirate the cyst , as that can cause an infection in the cyst that may spread into the joint itself.
Surgery involves removal of the cyst and the underlying bony spur. The operation is usually a day case procedure, which means you, can arrive and leave on the same day. It is usually performed with local anaesthetic, which means only your finger goes numb. Sometimes for large cysts the skin is turned around to cover the resulting defect, this is called a “”flap”.
A bulky finger dressing is applied after surgery. This is to protect the finger and keep the area clean and dry. We will usually see you back in the clinic at around 7-10 days for a wound inspection. The dressing is usually removed after 10-14 days and the sutures are removed.. The next appointment would be around 6 weeks. The incision/scar commonly remains tender and swollen for several weeks after surgery and can take months to fully “settle down”.
You may be able drive once the large dressing has been removed. You need to be able to perform an emergency stop safely and use the gear stick, steering wheel and hand brake without difficulty.
What are the potential complications?
The majority of patients are very satisfied with the outcome of surgery. Whilst uncommon, all surgical procedures are associated with some risks. Every effort is made to minimize these to ensure the best possible outcome from your surgery.
Infection - Uncommon occurs in approximately 1% of operations and usually treated very successfully with antibiotics. Very rarely would require further surgery
Delayed healing - Smokers and those with diabetes are more prone to this
Painful/Tender/thickened Scars - the vast majority of patients complain of some discomfort around the scar but it generally resolves with time. Wound care and desensitization as directed by your physiotherapist/hand therapist will improve this.
Nerve injury – small nerves that supply the skin around the scar may be injured giving a numb patch or unpleasant sensation round the scar. The use of magnification glasses ( Loupes) by your surgeon and very careful dissection will be used to minimise this complication
Stiffness - Operations to the finger may cause stiffness, this can be minimized by getting your hand/wrist moving as early as possible and working closely with your hand therapist if necessary.
Recurrence: This is uncommon but can occur in approximately 5 – 10 %.
CRPS – complex regional pain syndrome, this is an uncommon but serious complication. It can on rare occasions leave you with a less function hand with on-going pain stiffness and swelling. See section on CRPS. The exact incidence or rate of CRPS after surgery is unknown. It probably occurs in a significant form in approximately 1-2% of cases