Scaphoid nonunion.
Scaphoid nonunion is common, but the exact pathophysiology of this complication is unclear. Explanations include lack of treatment, poor initial treatment, delay in diagnosis, synovial fluid dynamics, precarious vascularity, fracture displacement, and carpal instability. Currently, the diagnosis is best confirmed by classic changes on plain radiographs, instability testing, arthrography, and arthroscopy in selected cases. Nine carpal bones are not benign. The natural history of scaphoid nonunion is one of progressive arthritis. Attempts at obtaining bony healing are therefore recommended. In treating established nonunions without arthritis, the Russe bone graft technique is the mainstay of treatment. A union rate of 90 per cent is to be expected. Electrical stimulation is an alternative when there is no synovial pseudarthrosis or scaphoid collapse deformity, or if a previous Russe graft has failed. If a significant humpback scaphoid or collapse deformity is present, internal fixation with the Herbert screw and scaphoid reconstruction with a bone graft are our choices. Healing rates are less than those with the Russe graft, but one may achieve improved motion of the wrist and earlier return to function. When scaphoid nonunion is accompanied by degenerative arthritis, salvage procedures are recommended. Radial styloidectomy is a simple procedure that will preserve motion and buy time. Soft tissue interposition with excision of a small proximal pole is useful, particularly if no collapse deformity is present. Silicone replacement alone has fallen into increasing disfavor because of the high incidence of subluxation and silicone synovitis. Combining silicone replacement with intercarpal fusion (the SLAC procedure) may lessen these complications. Proximal row carpectomy is another procedure that may preserve motion, though often at the expense of weakness, particularly in the younger patient requiring significant grip strength. In these cases, standard wrist fusion seems the most predictable alternative.