scaphoid nonunion advanced collapse

3 min read 19-03-2025

Meta Description: Scaphoid nonunion advanced collapse (SNAC) wrist is a debilitating condition. Learn about its causes, diagnosis, symptoms, treatment options (including surgery), and recovery. This comprehensive guide provides valuable information for patients and healthcare professionals.

What is Scaphoid Nonunion Advanced Collapse (SNAC)?

Scaphoid nonunion advanced collapse (SNAC) wrist is a serious complication of a scaphoid fracture that hasn't healed properly (nonunion). The scaphoid is a small bone in your wrist, crucial for its stability and function. When a scaphoid fracture fails to heal, it leads to progressive collapse of the wrist's carpal bones, resulting in significant pain, stiffness, and loss of function. This condition requires prompt diagnosis and often necessitates surgical intervention.

Causes of SNAC Wrist

The root cause of SNAC is a scaphoid fracture that doesn't heal. Several factors contribute to this:

Delayed or inadequate treatment: Initial mismanagement of the fracture, such as improper immobilization or insufficient time in a cast, significantly increases the risk.
Poor blood supply: The scaphoid has a limited blood supply, particularly in its distal pole (farther from the wrist). This makes it slow to heal, and fractures in this area are especially prone to nonunion.
Comminuted fractures: Fractures that shatter the scaphoid into multiple pieces are harder to heal.
Smoking: Smoking reduces blood flow, impairing healing.

Symptoms of SNAC Wrist

SNAC wrist often presents with a combination of symptoms that progressively worsen over time:

Wrist pain: This is usually the first symptom and can range from mild to severe.
Swelling: Inflammation around the wrist joint is common.
Limited range of motion: Difficulty bending and rotating the wrist.
Wrist instability: A feeling of weakness or giving way in the wrist.
Deformity: Over time, the collapse of the carpal bones can lead to visible deformity of the wrist.
Pain with gripping: Everyday activities like opening jars or turning doorknobs become difficult.

Diagnosing SNAC Wrist

Diagnosis involves a combination of:

Physical examination: Your doctor will assess your wrist's range of motion, palpate for tenderness, and check for instability.
X-rays: X-rays are essential to visualize the scaphoid fracture and assess the degree of carpal collapse. Specific radiographic features, such as radial shortening and capitolunate instability, are indicative of SNAC.
CT scan: A CT scan can provide more detailed images of the scaphoid and surrounding bones, aiding in surgical planning.
MRI: While less commonly used for initial diagnosis, MRI can help assess the quality of bone and soft tissue surrounding the scaphoid.

Treatment Options for SNAC Wrist

Treatment for SNAC wrist is primarily surgical, although non-surgical options might be considered in very early stages or specific cases.

Surgical Treatment

Several surgical procedures may be used to address SNAC, aiming to restore wrist stability and improve function:

Bone grafting: This involves filling the nonunion gap with bone graft material (autograft, allograft, or bone morphogenetic protein) to promote healing. This may be combined with internal fixation (screws or plates).
Proximal row carpectomy (PRC): This procedure involves removing the proximal row carpal bones (scaphoid, lunate, triquetrum), improving wrist alignment and function.
Four-corner fusion: This procedure fuses the four carpal bones (capitate, hamate, triquetrum, lunate), improving wrist stability.
Wrist arthrodesis (fusion): In severe cases, the entire wrist joint might be fused to provide stability. This limits mobility but eliminates pain.

Non-surgical Treatment

In some instances, especially very early in the progression of SNAC, non-surgical treatments like pain management and physical therapy might be attempted. However, these are usually not sufficient to prevent the progression of the disease.

Recovery and Rehabilitation After SNAC Wrist Surgery

Recovery from SNAC surgery can be lengthy and requires a dedicated rehabilitation program:

Immobilization: The wrist will be immobilized in a cast or splint for several weeks.
Physical therapy: This is crucial to regain range of motion, strength, and function. Therapy might include exercises, manual therapy, and modalities such as ultrasound.
Gradual return to activity: A gradual increase in activity is essential to avoid re-injury.

Long-Term Outlook for SNAC Wrist

The long-term outcome of SNAC wrist surgery depends on several factors, including the severity of the collapse, the chosen surgical procedure, and the patient's compliance with rehabilitation. While surgery aims to improve wrist function and alleviate pain, complete restoration to pre-injury levels is not always achievable. Some degree of stiffness or limited range of motion might persist.

Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment of any medical condition. They can help determine the best course of action based on your individual circumstances.