Pancarpal arthrodesis—often referred to as panarthrodesis—is a definitive surgical procedure designed to fuse all three major carpal joint levels:

• Antebrachiocarpal joint

• Middle carpal joint

• Carpometacarpal joints

Because it eliminates all motion in the carpus, this procedure is reserved for cases in which functional reconstruction is not possible. When performed correctly, pancarpal arthrodesis provides excellent long-term stability, pain relief, and return to acceptable limb function.

1. Indications for Pancarpal Arthrodesis

Panarthrodesis is indicated when the structural integrity of the carpus is irreversibly compromised. Common indications include:

Traumatic Conditions

• Complete antebrachiocarpal luxation

• High-grade hyperextension injuries

• Severe shearing injuries, often involving contamination or soft tissue loss

• Polytrauma with instability across multiple carpal joints

• Comminuted radial carpal bone fractures that cannot be reconstructed

Pathologic Conditions

• End-stage degenerative joint disease (DJD)

• Chronic instability unresponsive to orthoses or conservative management

• Infection destroying articular cartilage or ligamentous structures

Why Fusion Is Necessary

The carpus relies heavily on a complex arrangement of ligaments for stability. Once these structures are destroyed, the joint is biomechanically unstable and highly painful. Unlike other joints, the carpus cannot tolerate instability, and primary ligament repair is often impossible in severe injuries. For these reasons, arthrodesis becomes the only predictable option for pain relief and functional recovery.

2. Surgical Objectives and Pre-operative Considerations

Successful arthrodesis requires:

• Complete removal of all articular cartilage at the fusion sites

• Rigid internal or external fixation to eliminate motion

• Appropriate carpal positioning during fusion

• Adequate cancellous bone graft to enhance osteogenesis

The carpus is typically fused in 10–12° of extension, replicating the natural functional angle.

Advanced imaging (radiographs or CT) is recommended in cases with comminution, infection, or suspicion of concurrent fractures.

3. Surgical Technique

Step 1: Joint Preparation

All articular cartilage must be removed from:

• Antebrachiocarpal joint

• Middle carpal joint

• Carpometacarpal joints

Techniques may include:

• Curettage

• Rasping

• High-speed burr

Cartilage removal must expose bleeding subchondral bone to promote osteogenesis and eventual bony fusion. The exposed surfaces are then packed with autogenous cancellous bone graft, typically harvested from the proximal humerus, ilium, or proximal tibia.

Step 2: Implant Stabilization

Rigid stabilization is essential. Three major fixation options exist:

A. Dorsal Plate Technique

This traditional approach uses a plate applied to the dorsal surface and extending from the distal radius to the third metacarpal.

Technical considerations:

• A minimum seven-hole plate is required.

• The plate is pre-contoured to maintain ~10° of extension.

• The dorsal position places the plate under significant bending stress, especially during early weight-bearing.

• External support (splint or cast) is required until radiographic signs of fusion appear.

B. Palmar Plate Technique (Mechanically Superior)

Increasingly preferred, this technique places the plate on the tension (palmar) surface of the carpus.

Advantages:

• Biomechanically superior construct

• Lower bending stress on the plate

• More natural alignment of joint forces

• Faster return to functional weight-bearing

• Greater overall stability

The carpus is fused in 10–12° extension, replicating the normal standing angle.

C. External Skeletal Fixation (ESF)

A Type IIB ESF is indicated in:

• Severe shearing injuries with soft tissue compromise

• Open fractures or contaminated wounds

• Infection, where internal plates may be contraindicated

Considerations:

• Fusion time is longer (10–12+ weeks)

• Pin tract care is essential

• Frame removal occurs once radiographic fusion is confirmed

ESF is an excellent choice for temporary stabilization or when internal fixation cannot be safely used.

4. Functional Outcome and Prognosis

Despite eliminating all carpal motion, functional outcomes after pancarpal arthrodesis are generally excellent.

Documented Outcomes

• 97% of owners report improved gait

• 74% report normal or near-normal limb use

• Dogs reliably regain comfortable weight-bearing function

• Working and athletic dogs often return to moderated activity

Expected Changes in Gait

A noticeable circumduction (outward swing of the lower limb) may occur during the swing phase. This is a normal biomechanical adaptation to loss of carpal flexion.

5. Comparison to Partial Arthrodesis

Partial carpal arthrodesis fuses only the middle and carpometacarpal joints, preserving antebrachiocarpal flexion.

When Partial Arthrodesis Is Considered

• Injuries isolated to the middle/distal joints

• Preserved integrity of the antebrachiocarpal joint

• Mild hyperextension injuries

Advantages

• Better limb flexibility

• More natural gait cycle

• Reduced circumduction

However, partial arthrodesis is less common because many carpal injuries—especially hyperextension injuries—affect the primary weight-bearing joint, making panarthrodesis the more reliable option.

6. Prognostic Factors

Better outcomes are associated with:

• Early surgical intervention

• Proper carpal alignment (10–12° extension)

• Adequate grafting

• Accurate plate contouring and screw placement

• Strict postoperative immobilization

Complications may include delayed union, implant failure (dorsal technique), pin tract infection (ESF), or incomplete fusion.

Surgeon-Facing FAQ: Pancarpal Arthrodesis

1. Why is complete cartilage removal essential?

Any retained cartilage prevents bone-to-bone contact and can lead to nonunion.

2. When should ESF be chosen over internal plating?

In contaminated wounds, severe shearing injuries, or cases with active infection where internal implants are unsafe.

3. Why is palmar plating considered biomechanically superior?

It places the implant on the tension side, where forces act more favorably, reducing implant fatigue and promoting faster fusion.

4. What is the optimal carpal angle for fusion?

10–12° of extension, approximating the natural standing posture.

5. How long is external coaptation required after plating?

Typically 6–8 weeks, until radiographic evidence of early fusion appears.

6. What are the most common complications?

Implant failure with dorsal plates, delayed union, pin tract infection (ESF), and carpal malalignment.