It is important that the radioscaphocapitate ligament is left intact, because if the ligament is not preserved the capitate bone will translate to the ulnar side of the wrist and move away from the distal radius. The new formed joint between the capitate and the lunate fossa of the distal radius is not as congruent as the former scaphoid-lunate-radius joint, however the results of proximal row carpectomy are generally excellent. In patients older than 40 years proximal row carpectomy is preferred because these patients have a small chance of developing osteoarthritis in the new formed capitate-radial joint during their remaining life.Patients younger than 40 years have a big chance to develop osteoarthritis in the radiocapitate joint. These patients have longer to live, therefore the incongruence of the joint will exist for a longer time. Thus, in this patient population four-corner arthrodesis is the treatment of first choice. The capitate, lunate, hamate and triquetrum are bounded together in this procedure and the scaphoid is excised. Before the arthrodesis is executed, the lunate must be reduced out of DISI position. Because the radiolunate joint is typically preserved in stage II SLAC and SNAC wrists, this joint can be the only remaining joint of the proximal wrist. Both procedures are often combined with wrist denervation, as described in the text of treatment stage I. Stage III
The only treatment option for stage III wrist osteoarthritis is four-corner arthrodesis, as described above in stage II.
There are a number of tests and actions that can be performed when a patient is suspected of having osteoarthritis caused by SLAC or SNAC.SLAC:

Tenderness 1 cm above Lister’s tubercleTests:

Watsons test
Finger extension testSNAC:

Tenderness at the anatomical snuff box
Painful pronation and supination when performed against resistance
Pain during axial pressure

X-rays
Osteoarthritis between the radius bone and the carpals is indicated by a radiocarpal joint space of less than 2mm.SLAC

Because SLAC results from scapholunate ligament rupture, there is a larger space between the two bones, also known as the Terry Thomas sign. Osteoarthritis and a space larger than 3 mm is suspicious and a space larger than 5 mm is a proven SLAC pathology. Scaphoid instability due to the ligament rupture can be stactic or dynamic. When the X-ray is diagnostic and there is a convincing Terry Thomas sign it is a static scaphoid instability. When the scaphoid is made unstable by either the patient or by manipulation by the examining physician it is a dynamic instability.SNAC
In order to diagnose a SNAC wrist you need a PA view X-ray and a lateral view X-ray. As in SLAC, the lateral view X-ray is performed to see if there is a DISI.Computed tomography (CT) or Magnetic Resonance Imaging (MRI) are rarely used to diagnose SNAC or SLAC wrist osteoarthritis because there is no additional value. Also, these techniques are much more expensive than a standard X-ray. CT or MRI may be used if there is a strong suspicion for another underlying pathology or disease.