Causes / typical injury mechanism: Chronic, untreated scapholunate interosseous ligament injury

Classic history and presentation: Although not always symptomatic, patients usually present with wrist pain, aggravated by heavy or repetitive use; decreased range of motion; and grip weakness. Patients may experience pain with activities such as pull-ups and pushing themselves up out of a seated position. There may be a remote history of acute or repetitive trauma to the hand, wrist, or forearm, although nontraumatic etiologies also exist.

Prevalence:

• Age – Mean age 53 years
• Sex / gender – 4:1 male to female ratio

Risk factors:

• Manual laborer
• History of wrist trauma

Pathophysiology: Scapholunate interosseous ligament disruption leads to dorsal intercalated segment instability (DISI) wherein the scaphoid and lunate bones no longer move in tandem, causing alteration of dynamic forces across the midcarpal and radiocarpal joints of the wrist. This, in turn, incites cartilage erosion and a predictable pattern of arthritis development, eventually culminating in carpal collapse.

Grade / classification system: Watson classification (radiographic classification schema) –

• Grade 1: Osteoarthritis between the radial styloid and scaphoid
• Grade 2: Osteoarthritis of the entire scaphoid fossa
• Grade 3: Osteoarthritis of the scaphoid fossa and capitolunate joint

Note: Osteoarthritis spares the radiolunate joint.