Four-corner fusion (wrist)

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Four-corner fusion is a partial fusion technique used in some patients with advanced degenerative change in the wrist. Partial fusion reduces pain from the joint while still preserving some motion (as opposed to a total wrist fusion).

Indications

Advanced arthritis from

• scapholunate advanced collapse (SLAC wrist)
• scaphoid nonunion advanced collapse (SNAC wrist)

Procedure

The procedure involves intercarpal arthrodesis of the capitate, lunate, triquetrum, and hamate bones of the wrist. The four corners of the bones are attached with a spider plate. The scaphoid is resected and used as an autologous bone graft. 

Technique

• make an incision on the dorsal aspect of the forearm
• identify the extensor retinaculum and make an incision through the third extensor compartment, releasing the extensor pollicis longus
• elevate the fourth dorsal compartment and ulnarly retract the extensor tendons of the fourth compartment
• incise the capsule and the identify the radius, lunate, triquetrum, the hamate, and capitate
• If the lunate is in a DISI formation and the capitate has shifted radially, place the hand into finger traps and use weights to distract the wrist
• excise the scaphoid
• remove the cartilage between the lunate, the capitate, triquetrum, and hamate within the intercarpal joint spaces
• flex the wrist to place the lunate into a neutral position as much as possible
• stabilize the lunate in this position with a K-wire from the distal dorsal radius into the lunate without crossing into the joint space between the lunate and capitate
• with the lunate stabilized, extend the wrist at the lunate-capito junction
• add two additional K-wires to stabilize the triquetrum to the capitate
• attach the spider plate at the junction of the four corners and secure to all four bones with the use of screws
• fluoroscopically confirm the placement of the screws
• close the wrist capsule and suture skin

Postprocedure care

Immobilize the wrist for two weeks.

Outcomes

• 100% of patients report a significant improvement in pain relief
• ∼50% report a significant improvement of flexion extension, (only 40% of radioulnar deviation)
• grip strength ∼50% of the contralateral side
• majority of complications occur within in the first 2 years after surgery

Alternative procedures include

• proximal row carpectomy
• three-corner fusion (both triquetrum and scaphoid are excised)