VISI (Volar Intercalated carpal Instability)

Volar Intercalated Carpal Instability (VISI)

Introduction

Volar Intercalated Carpal Instability, commonly abbreviated as VISI, is a complex wrist condition characterized by abnormal alignment and instability of the carpal bones, particularly involving the lunate bone. This condition results in the lunate tilting towards the volar (palm) side of the wrist, disrupting the normal biomechanics and function of the wrist joint. VISI is one of the several patterns of carpal instability and can significantly affect wrist movement, strength, and overall hand function if left untreated.

Anatomy of the Wrist

To understand VISI, it is important to first understand the anatomy of the wrist. The wrist is composed of eight small bones called carpal bones, arranged in two rows: the proximal row (scaphoid, lunate, triquetrum, and pisiform) and the distal row (trapezium, trapezoid, capitate, and hamate). These bones are connected by a complex network of ligaments that provide stability while allowing a wide range of motion.

The lunate bone is centrally located in the proximal row and plays a crucial role in wrist stability and movement. It articulates with the radius bone of the forearm proximally and with other carpal bones distally. The stability of the lunate is maintained by several ligaments, including the scapholunate and lunotriquetral ligaments.

What is VISI?

In VISI, the lunate bone tilts volarly (towards the palm) due to disruption or laxity of the lunotriquetral ligament. This causes the lunate to lose its normal alignment with the other carpal bones, leading to abnormal wrist mechanics. The instability can cause the lunate to flex forward while the scaphoid extends backward, creating a characteristic deformity visible on wrist X-rays

VISI is often contrasted with Dorsal Intercalated Carpal Instability (DISI), where the lunate tilts dorsally (towards the back of the hand). Both conditions represent different patterns of carpal instability and require distinct approaches to diagnosis and treatment.

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Causes of VISI

VISI can develop due to several reasons, including:

Trauma: Acute wrist injuries such as sprains, fractures, or dislocations can damage the lunotriquetral ligament, leading to VISI. Falls on an outstretched hand are a common cause.
Chronic ligament laxity: Repetitive strain or overuse of the wrist, especially in athletes or manual laborers, can weaken the ligaments over time.
Inflammatory conditions: Diseases like rheumatoid arthritis can cause ligament weakening and joint destruction, predisposing to VISI.
Degenerative changes: Age-related wear and tear can lead to ligament degeneration and instability.
Congenital factors: Rarely, some individuals may have inherent ligamentous laxity or anatomical variations that predispose them to VISI.

Symptoms and Clinical Presentation

Patients with VISI typically present with:

Wrist pain: Often localized to the volar (palm) side of the wrist, pain may worsen with activity or gripping.
Swelling and tenderness: Around the lunotriquetral joint.
Decreased range of motion: Difficulty in bending or extending the wrist fully.
Weakness: Reduced grip strength and difficulty performing tasks requiring wrist stability.
Instability or clicking: Some patients may feel or hear a clicking or popping sensation during wrist movement.
Chronic symptoms: If untreated, VISI can lead to chronic wrist pain, stiffness, and eventually arthritis.

Diagnosis

Diagnosing VISI involves a combination of clinical examination and imaging studies:

Physical examination: The doctor will assess wrist range of motion, tenderness, swelling, and perform specific tests to evaluate ligament integrity.
X-rays: Standard wrist X-rays, including posteroanterior (PA), lateral, and oblique views, can reveal the characteristic volar tilt of the lunate. Stress views or clenched fist views may be used to better visualize instability.
MRI: Magnetic Resonance Imaging provides detailed images of soft tissues, including ligaments, and can detect partial or complete tears of the lunotriquetral ligament.
CT scan: Useful for assessing bone alignment and associated fractures.
Arthroscopy: In some cases, minimally invasive wrist arthroscopy may be performed to directly visualize ligament damage and assess joint surfaces.

Treatment Options

The treatment of VISI depends on the severity of the instability, the duration of symptoms, and the patient’s functional demands.

Non-Surgical Treatment

Immobilization: Wrist splints or casts may be used to immobilize the wrist and allow healing of partial ligament injuries.
Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) help reduce pain and inflammation.
Physical therapy: Once pain subsides, therapy focuses on strengthening the wrist muscles, improving range of motion, and enhancing proprioception to stabilize the joint.
Activity modification: Avoiding activities that exacerbate symptoms is important during recovery.
Arthroscopy: In some cases, minimally invasive wrist arthroscopy may be performed to directly visualize ligament damage and assess joint surfaces.

Non-surgical treatment is generally reserved for mild cases or early-stage VISI without significant ligament disruption.

Surgical Treatment

Surgery is considered when conservative measures fail or in cases of complete ligament tears and chronic instability. Surgical options include:

Ligament repair or reconstruction: Direct repair of the lunotriquetral ligament or reconstruction using tendon grafts to restore stability.
Capsulodesis: Tightening of the joint capsule to limit abnormal movement.
Partial wrist fusion: In cases with advanced instability or arthritis, fusing certain carpal bones can provide pain relief and stability.
Proximal row carpectomy: Removal of the proximal row of carpal bones may be considered in severe cases to preserve some wrist motion.
Wrist arthrodesis: Complete wrist fusion is a last resort for severe arthritis and instability, sacrificing motion for pain relief and stability.

Prognosis and Long-Term Outcomes

The prognosis of VISI depends largely on early diagnosis and appropriate treatment. Mild cases treated conservatively often have good outcomes with restoration of function and pain relief. However, untreated or chronic VISI can lead to progressive wrist instability, cartilage damage, and arthritis, resulting in chronic pain and disability.

Surgical treatment can effectively restore stability and function, but outcomes vary depending on the extent of ligament damage and joint degeneration at the time of surgery. Rehabilitation after surgery is crucial for regaining strength and motion.

Prevention and Patient Advice

While not all cases of VISI can be prevented, certain measures can reduce the risk:

Protect the wrist: Use protective gear during sports or activities with high risk of wrist injury.
Avoid repetitive strain: Take breaks and use ergonomic tools to minimize wrist overuse.
Early treatment of wrist injuries: Prompt evaluation and management of wrist sprains or fractures can prevent progression to instability.
Maintain joint health: Regular exercise, a balanced diet, and managing inflammatory conditions can help preserve ligament and joint integrity.

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