Carpectomy: Understanding Wrist Anatomy, Types, Indications, and Recovery

What is a Carpectomy?

A carpectomy is a surgical procedure involving the removal of one or more carpal bones in the wrist, most commonly the proximal row, to alleviate chronic pain and improve function in cases of severe wrist arthritis or instability.

Understanding the Wrist Anatomy

To grasp the concept of a carpectomy, it's essential to understand the intricate anatomy of the wrist. The wrist joint, or radiocarpal joint, is a complex structure comprising the distal ends of the forearm bones (radius and ulna) and eight small, irregularly shaped carpal bones, which are arranged into two rows:

• Proximal Row: Closest to the forearm, consisting of the scaphoid, lunate, triquetrum, and pisiform. These bones articulate primarily with the radius and ulna.
• Distal Row: Closest to the hand, consisting of the trapezium, trapezoid, capitate, and hamate. These bones articulate with the metacarpal bones of the hand.

These carpal bones, along with numerous ligaments, form a highly mobile and stable structure crucial for the wide range of wrist movements and the transmission of force from the hand to the forearm. Damage, degeneration, or instability within these small joints can lead to significant pain, stiffness, and functional limitations.

What is a Carpectomy?

A carpectomy is a surgical intervention that involves the excision (removal) of one or more of these carpal bones. The primary goal of this procedure is to reduce chronic wrist pain, preserve a degree of wrist motion, and improve overall function in a wrist severely affected by arthritis or certain conditions that lead to carpal bone degeneration. Unlike a wrist fusion (arthrodesis), which eliminates all motion in exchange for stability and pain relief, a carpectomy aims to retain some functional movement.

Types of Carpectomy

While various carpal bones can be removed depending on the specific pathology, the most common and well-established type of carpectomy is:

• Proximal Row Carpectomy (PRC): This is the most frequently performed carpectomy. It involves the removal of the three main bones of the proximal carpal row: the scaphoid, lunate, and triquetrum. After these bones are removed, the capitate (the largest bone in the distal carpal row) articulates directly with the radius, effectively creating a new joint. This procedure aims to eliminate the painful bone-on-bone grinding of the arthritic proximal carpal row while allowing the wrist to retain a functional range of motion, typically 50-70% of the pre-injury range.
• Partial Carpectomy: In some specific cases, only a single damaged carpal bone or a select few might be removed. For example, a scaphoidectomy might be performed if the scaphoid bone is severely arthritic or necrotic and causing significant issues.

Indications for Carpectomy

A carpectomy is typically considered a "salvage" procedure, meaning it's performed when less invasive treatments have failed and the wrist joint is severely compromised. Common indications include:

• Scaphoid Non-Union Advanced Collapse (SNAC Wrist): A common form of wrist arthritis resulting from an untreated or poorly healed scaphoid fracture, leading to progressive collapse and arthritis of the carpal bones.
• Scapholunate Advanced Collapse (SLAC Wrist): Degenerative arthritis caused by a long-standing injury to the scapholunate ligament, leading to instability and subsequent arthritis.
• Kienböck's Disease: A condition characterized by the avascular necrosis (death due to lack of blood supply) of the lunate bone, leading to pain and collapse.
• Severe Post-Traumatic Arthritis: Arthritis that develops as a consequence of significant wrist trauma, such as fractures or dislocations, which have led to irreversible joint damage.
• Osteoarthritis: While less common than in other joints, severe primary osteoarthritis affecting the carpal bones can also be an indication.
• Failed Previous Wrist Surgeries: In some cases, a carpectomy might be performed if previous attempts at wrist reconstruction or repair have not yielded satisfactory results.

The Surgical Procedure

A carpectomy is performed under general or regional anesthesia. The surgeon makes an incision on the back of the wrist to access the carpal bones. For a proximal row carpectomy, the scaphoid, lunate, and triquetrum bones are carefully dissected and removed. Any remaining rough bone surfaces on the capitate or radius are smoothed to facilitate the new articulation. The incision is then closed, and the wrist is typically immobilized in a splint or cast. The procedure generally takes 1 to 2 hours.

Post-Operative Recovery and Rehabilitation

Rehabilitation is a critical component of a successful carpectomy outcome. It's a structured process designed to restore range of motion, strength, and function.

• Immediate Post-Operative Phase (Weeks 0-2):
  • The wrist is immobilized in a cast or splint to protect the healing tissues.
  • Focus is on pain management, swelling control (elevation, ice), and maintaining mobility of the fingers, elbow, and shoulder.
• Early Rehabilitation Phase (Weeks 2-6):
  • The cast or splint may be removed, and gentle passive and active-assisted range of motion exercises for the wrist are initiated by a hand therapist.
  • The goal is to prevent stiffness and gradually increase wrist mobility without stressing the healing structures.
  • Light gripping exercises may be introduced.
• Intermediate Rehabilitation Phase (Weeks 6-12):
  • Progression to active range of motion exercises.
  • Introduction of light strengthening exercises (e.g., isometric contractions, then low-resistance isotonic exercises) for the wrist and grip.
  • Focus on improving endurance and functional use of the hand.
• Advanced Rehabilitation Phase (Months 3-6+):
  • Progressive strengthening with increasing resistance.
  • Integration of proprioceptive exercises to improve joint awareness and control.
  • Sport-specific or activity-specific training, if applicable.
  • Return to heavy lifting, impact activities, or sports is gradual and guided by the therapist and surgeon, often taking 6 to 12 months, or even longer, depending on the individual and the demands of their activities.

Adherence to the prescribed rehabilitation program is paramount for achieving the best possible functional outcomes and minimizing long-term complications.

Potential Risks and Complications

As with any surgical procedure, carpectomy carries certain risks, including:

• General Surgical Risks: Infection, bleeding, adverse reaction to anesthesia, nerve damage, or blood clots.
• Specific Carpectomy Risks:
  • Persistent Pain: While the goal is pain relief, some residual pain may remain.
  • Stiffness and Limited Range of Motion: Although designed to preserve motion, some degree of stiffness or reduced motion compared to a healthy wrist is expected.
  • Reduced Grip Strength: Most patients experience some decrease in grip strength.
  • Complex Regional Pain Syndrome (CRPS): A rare but severe chronic pain condition.
  • Progression of Arthritis: While PRC typically delays further arthritic changes, the newly formed joint between the capitate and radius can, over many years, develop arthritis.
  • Non-Union or Mal-Union: Although rare with bone removal, issues with soft tissue healing can occur.

Outcomes and Long-Term Considerations

For properly selected patients, a carpectomy, particularly a proximal row carpectomy (PRC), is generally considered a highly effective procedure for alleviating wrist pain and improving functional use. Patients typically experience significant pain relief and are able to perform most daily activities. While full pre-injury range of motion and strength are rarely regained, the retained motion is often sufficient for functional tasks.

Long-term studies on PRC show good durability, with many patients experiencing lasting relief for decades. However, it's important to understand that the wrist will never be "normal," and some limitations in heavy lifting or repetitive strenuous activities may persist. The potential for the new capitate-radial joint to develop arthritis over a very long period exists, but this is often a slow process.

Carpectomy vs. Wrist Fusion (Arthrodesis)

When faced with severe wrist arthritis, surgeons often consider two main "salvage" procedures: carpectomy and wrist fusion (arthrodesis).

• Carpectomy: Aims to relieve pain while preserving some wrist motion. It's a good option for patients who require a degree of wrist flexibility for their daily activities or occupation.
• Wrist Fusion (Arthrodesis): Involves permanently joining the bones of the wrist, eliminating all wrist motion. This provides excellent pain relief and stability but sacrifices movement. Fusion is often considered for more widespread, severe arthritis, when motion preservation is less critical than complete pain relief and stability, or if a carpectomy has failed.

The choice between these procedures depends on the patient's specific condition, functional demands, activity level, and the surgeon's assessment.

Conclusion

A carpectomy is a well-established surgical option for individuals suffering from chronic, debilitating wrist pain and dysfunction due to advanced arthritis or specific carpal bone conditions. By carefully removing damaged carpal bones, the procedure aims to significantly reduce pain while preserving a functional range of motion, offering a valuable alternative to complete wrist fusion. Success hinges on accurate diagnosis, skilled surgical execution, and, critically, dedicated adherence to a comprehensive post-operative rehabilitation program. Patients considering this procedure should have a thorough discussion with their orthopedic surgeon to understand the benefits, limitations, and expected outcomes specific to their condition.