Scapholunate advanced collapse

Scapholunate advanced collapse 91M - CR ap - 001

Scapholunate Advanced Collapse (SLAC) is a progressive condition affecting the wrist, characterized by a specific pattern of osteoarthritis and carpal instability. It is most commonly the result of untreated or chronic scapholunate ligament injuries, leading to a characteristic pattern of degenerative changes in the wrist. This condition is the most common form of carpal instability and is a significant cause of wrist pain and functional impairment.

Etiology

SLAC wrist develops following a disruption or weakening of the scapholunate ligament, which is a critical stabilizer of the wrist joint. This ligament connects the scaphoid and lunate bones, two of the eight small bones in the wrist. Injury to this ligament can occur from acute trauma, such as a fall on an outstretched hand, or from chronic stress and wear. Over time, the instability in the scapholunate joint leads to abnormal motion and wear of the wrist bones, particularly the scaphoid, lunate, and the radial aspect of the radius bone, resulting in osteoarthritis.

Pathophysiology

The progression of SLAC wrist involves several stages, each marked by increasing degrees of joint degeneration and instability:

• Stage I: Characterized by evidence of scapholunate dissociation and early signs of arthritis between the scaphoid and the radial styloid.
• Stage II: Progression of arthritis to involve the entire scaphoid fossa of the radius.
• Stage III: Capitate, lunate, and triquetrum involvement, with arthritis spreading to the midcarpal joint.
• Stage IV: Involvement of the radiocarpal joint, indicating a pan-carpal arthritis.

Symptoms

Patients with SLAC wrist typically present with chronic wrist pain, exacerbated by motion, especially gripping and lifting. There may be a decrease in wrist range of motion, and in advanced stages, visible deformity and significant functional impairment can occur.

Diagnosis

Diagnosis of SLAC wrist is primarily based on clinical examination and confirmed with imaging studies. X-rays of the wrist in various projections can reveal the characteristic patterns of arthritis and bone changes. Advanced imaging techniques such as MRI or CT scans can provide more detail about the condition of the ligaments and the extent of the degenerative changes.

Treatment

Treatment of SLAC wrist aims to relieve pain and restore function. Options include:

• Non-surgical: Initial treatment often involves immobilization of the wrist, nonsteroidal anti-inflammatory drugs (NSAIDs), and physical therapy. Corticosteroid injections may also be used to reduce inflammation and pain.
• Surgical: In cases where non-surgical treatment fails to provide relief, or the condition is in an advanced stage, surgery may be necessary. Surgical options include proximal row carpectomy, scaphoid excision and four-corner fusion, or total wrist arthrodesis. The choice of surgery depends on the stage of the disease, the patient's activity level, and the presence of other health conditions.

Prognosis

The prognosis for SLAC wrist varies depending on the stage at diagnosis and the treatment chosen. Early intervention can slow the progression of the disease and alleviate symptoms, but advanced stages may require more invasive treatments and can result in significant limitations.

Prevention

Preventing SLAC wrist involves early detection and treatment of scapholunate ligament injuries. Proper protective gear and caution during activities that pose a risk to the wrist can also reduce the likelihood of injury.