Definition of synovial cysts:
Synovial cysts are one of the most common pathologies of the wrist, they appear as swelling that is more or less round in shape (wrist ball).
The synovial cyst corresponds to a hernia of the wrist joint; the capsule and the synovial tissue form a membrane that holds the articular fluid inside the wrist joint. This membrane acts as a pouch that can fistulise out of the joint to form a synovial lump, which is the synovial cyst of the wrist. In common parlance, this is often referred to as ganglion cyst of the wrist.
Video of arthroscopic treatment of a dorsal synovial cyst at the wrist:
Diagnosis of synovial cysts:
For a synovial cyst of the wrist, the diagnosis is primarily clinical; it is a harmless swelling (supple, depressible, painless, does not adhere to the skin)..
Synovial cysts of the wrist can occur spontaneously, which is the usual diagnosis, but also secondary to an injury, a fall on the wrist, presumably not serious. Synovial cysts can occur at any age in female as well as male subjects.
Most of the time, synovial cysts of the wrist have no specific cause, in which case they are called idiopathic cysts. However they may also be associated with osteo-articular pathologies: wrist hyperlaxity, severe wrist sprains, wrist osteoarthritis.
Nearly all synovial cysts are asymptomatic, which means that they do not cause any discomfort. These should not be treated and thus require no surgery.
However a synovial cyst may cause wrist pain or cause loss of strength or mobility, especially for end of range motion. These symptomatic cysts (painful) can be treated by arthroscopic surgery, with a highly specialized procedure.
The synovial cyst can develop at the front of the wrist, above the wrist’s flexion crease, in which case it is called a volar synovial cyst. More often, synovial cysts can form on the back of the wrist, in which case the term dorsal synovial cyst is used. Sometimes the synovial cyst may be invisible and manifests itself as isolated wrist pain.
The interview will look for any injuries to the wrist. The clinical examination will look for signs of wrist hyperlaxity, reduced motion range or wrist strength, or commonly associated dorsal extensor synovitis.
The only relevant additional examination of a synovial cyst of the wrist is a simple x-ray of the wrist that will find or rule out an underlying osteo-articular pathology. Although often prescribed, ultrasound has little practical use. Exceptionally, an MRI scan can be taken preoperatively in formes frustes to determine the exact articular origin of the synovial cyst: volar synovial cysts often originate from the wrist’s radiocarpal joint, dorsal synovial cysts from the mediocarpal joint.
When the cyst causes discomfort, arthroscopic wrist surgery will remove (exeresis) the synovial cyst from the wrist and treat the associated wrist pathologies.
Benefit of arthroscopy in ganglion cyst surgery:
With arthroscopic surgery of synovial cysts of the wrist, it is possible to treat this articular condition by approaching the wrist joint directly.
Arthroscopy has thus many advantages:
1. diagnostic benefit: wrist arthroscopy makes it possible to diagnose frequent joint defects associated with synovial cysts, which are not visible in open surgery
2. therapeutic benefit:
- arthroscopic surgery makes it possible to perform an articular synovectomy, which is often required around the synovial cyst.
wrist arthroscopy leaves smaller scars. Most of the time, only two 2-mm incisions are necessary; these will not require suturing.
arthroscopic surgery also makes it possible to perform a synovectomy of the wrist’s extensors.
For all these reasons, arthroscopic synovial cyst surgery makes it possible to greatly speed up wrist recovery and hand convalescence whilst reducing operative morbidity and the risk of complications: bruising, wrist pains, healing problems.
The two following studies on synovial cysts compare traditional open wrist surgery and arthroscopic wrist surgery for synovial cyst removal; these comparative studies underline the benefits of arthroscopy in wrist surgery:
- Kang L, Akelman E, Weiss A-PC. Arthroscopic versus open dorsal ganglion excision: a prospective, randomized comparison of rates of recurrence and of residual pain. J Hand Surg 2008;33(4):471–5.
- Rocchi L, Canal A, Fanfani F, Catalano F. Articular ganglia of the volar aspect of the wrist: arthroscopic resection compared with open excision. A prospective randomised study. Scand J Plast Reconstr Surg Hand 2008;42(5):253–9.
Arthroscopy procedure for synovial cysts:
When discomfort in the wrist and hand persists, surgery is indicated.
This surgery can only be performed by a wrist specialist. The surgery is performed with the hand numbed, on an outpatient basis.
The wrist is placed under light traction, a 1.9-mm arthroscope (camera) is used with two shaver blades: one 2 mm in diameter, the other 2.9 mm in diameter.
Volar synovial cyst:
For volar synovial cysts, two 2-mm radiocarpal arthroscopic portals on the dorsal side are necessary: one 4-5 optical portal and one 3-4 instrumental portal. Surgery begins by a complete assessment of damage to capsules and ligaments, and then joint synovectomy is performed based on the peroperative findings.
The specialized surgeon uses a shaver to perform a capsular fenestration between the radioscaphocapitate (RSC) and long radiolunate ligaments, allowing the cystic fluid to be removed. Wrist surgery proceeds with the gradual excision the cyst’s membrane achieved by applying gradual pressure on the cystic lump.
Dorsal synovial cyst:
For dorsal synovial cysts, two 2-mm mediocarpal arthroscopic portals on the dorsal side are necessary: one ulnar midcarpal (UMC) optical portal and one radial midcarpal (RMC) instrumental portal that can be swapped during the procedure. Exceptionnally, an additional radiocarpal portal may be needed.
This surgery begins with a complete assessment of ligament and articular damage associated with dorsal mediocarpal synovectomy.
The hand surgeon then makes a capsular fenestration below the dorsal intercarpal ligament using a shaver; usually this incision in the capsule makes it possible to remove the fluid from the cyst. When the cyst is pierced, a yellowish cloudy fluid gushes into the wrist joint. Arthroscopic surgery proceeds with gradual excision of the cyst’s membrane, allowing the extensor tendons of the fingers and the wrist to be exposed. Proper arthroscopic synovectomy of the extensors can be performed.
The 2-mm surgical incisions do not need sutures, the bandage on the wrist can be removed after one week.
Wrist recovery after arthroscopic surgery on synovial cyst
The hand and fingers can be used immediately after surgery. The wrist will be immobilized with a removable splint for 15 days. Single-layer bandaging can be removed after one week. All daily life movements involving the wrist must resume gradually after 15 days. Full force and full resistance movements should be avoided for a month. Typically, discomfort and some pain in the wrist are felt in resistive movements for about 3 months.
The permanent cosmetic result of healing is visible after 6 months, which corresponds to the time needed for physiological skin remodelling. Wrist scars become almost invisible after 6 months.