Figure 1: Healed Lunocapitate fusion with scaphoid and triquetralexcision using a screw for fixation. Note the ‘hole’ in the radius where bone graft was taken from.
Wrist arthritis is very common. There are a number of reasons that arthritis of the wrist occurs: from scaphoid fractures, ligament injuries, distal radius fractures, metabolic diseases (involving altered body chemistry) or just from plain old wear and tear.
Fortunately, there are some very predictable procedures that can be used to treat wrist arthritis. Initial treatment is non-operative, including splints, steroid injections, and avoiding painful activities. If these don’t work, and the wrist is painful enough, the best treatment option is often a partial fusion. This means fusing some of the small bones of the wrist, while leaving other joints alone to retain some motion.
Which partial fusion is best for a particular patient depends upon where the arthritis is. Most commonly, the best option involves excising the scaphoid bone (which is usually involved in the arthritis) and performing a “mid-carpal fusion”.
Figure 2: Healed Lunocapitate fusion with scaphoid and triquetralexcision using two staples for fixation. Note the ‘hole’ in the radius where bone graft was taken from.
I published a paper in 2003 analyzing mid-carpal wrist fusions. The conclusion was that wrist motion is improved by always excising the scaphoid, regardless of whether or not it is involved with arthritis.1 Traditionally, the mid-carpal fusion involves a “four corner fusion”. The four corner fusion is performed by taking bone graft from your distal radius (the large bone of the wrist) and placing 2 screws into the remaining four major bones of your wrist. The wrist is casted for 6 weeks after surgery and then hand therapy is started.
More recently, a procedure that only fuses two bones, the lunate and capitate, has become popular. I prefer this technique as it is less surgery, is less painful, heals quickly, and has a low complication rate. The scaphoid is still excised and distal radius bone graft is still used. If the triquetrum (the other bone next to the lunate) has arthritis on it, it is also excised. The lunate and capitate are stabilized by either a single screw or two staples. The wrist is casted for 4-6 weeks after surgery and then hand therapy is started.
The success rate for mid-carpal fusions is very high, and the complication rate is low. How much motion the wrist has after surgery depends on how much motion the wrist has before surgery. If motion is near normal, up to roughly 50% of motion is retained. In addition, the fusion provides pain relief, strength and stability. If motion is poor, which is usually the case, the amount of motion loss is often less. Regardless, the ability to retain some motion is desirable, and the amount of motion retained is usually functional.
1) Management of the Scaphoid During Four Corner Fusion – A Cadaveric Study, Kobza PE, Budoff JE, Yeh ML, Luo ZP, The Journal of Hand Surgery, Vol 28A:904-9, 2003
