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Scapho-lunate advanced collapse arthritis

Scapho-lunate advanced collapse arthritis or SLAC occurs as the result of unrecognised injury to the ligament between the scaphoid and the lunate. This ligament is a very important one in the wrist and is the most frequently injured in falls onto the outstretched hand. In one sense it is fortunate that ligaments are stronger than bone, as falls usually result in a fracture rather than a tear of the ligament. Bone heals much better than ligaments!

Once the connection between the scaphoid and the lunate is lost, the two bones will move eccentrically and over time that leads to wear. This usually starts on the thumb side of the wrist, between the scaphoid and the forearm bone, the radius. Pain and a feeling of weakness when the wrist is loaded are the most frequent symptoms. Arising from a chair or the bath, doing a press-up or carrying something heavy with the palm up are common problems. Unfortunately by the time someone presents with a SLAC wrist we are into a 'salvage' situation. Almost by definition, the wrist is too far gone to be reconstructed.

Investigations will include a plain x-ray, probably a MRI scan, possbily screening under a x-ray machine and occasionally even an arthroscopy (key-hole examination of the inside of the joint). This will allow an assessment of the severity of the damage and treatment depends on this. The aim of all types of treatment is firstly to relieve pain and secondly to improve function. It is important to recognise that by being diagnosed with a SLAC wrist it is not possible to reverse time and regain a normal wrist. It is always going to be a compromise!

The options for treatment are as follows:

  1. Do nothing and modify one's activities to fit in with the wrist.
  2. Posterior and anterior interosseous neurectomy with or without a radial styloidectomy.
  3. Scaphoid excision and four corner fusion.
  4. Proximal row carpectomy.
  5. Total wrist fusion.
  6. Wrist replacement.

S.N.A.C. wrist

Scaphoid non-union advanced collapse is a different variation of the SLAC wrist. Failure of the scaphoid to unite following a fracture can result in a similar picture of arthritis. The initial investigation is very similar to the SLAC wrist and the options for treatment much the same.