Volar approach to the wrist

Introduction

The most common application of the volar approach to the wrist is decompression of the median nerve for carpal tunnel syndrome. This surgical technique provides excellent access to the anterior wrist structures.

Other Indications for the Volar Wrist Approach

• Flexor tendon synovectomy
• Removal of a carpal tunnel tumor
• Nerve and tendon repair within the carpal tunnel
• Drainage of sepsis extending from the midpalmar space
• Open reduction and internal fixation of certain distal radius and carpal fractures and dislocations, including volar lip fractures of the radius

Patient Positioning

• Place the patient supine on the operating table.
• The forearm is positioned supinated on a hand table, with the palm facing upward. Use a tourniquet.

Landmarks and Incision

Landmarks

1. Thenar crease
2. Transverse skin crease of the wrist
3. Palmaris longus tendon

Incision

• Begin the incision directly on the ulnar side of the thenar crease, approximately one-third of the way into the hand.
• Extend it proximally, staying just on the ulnar side of the thenar crease until nearly reaching the wrist flexion crease. To avoid skin healing problems, do not cross into the thenar crease itself.
• Then curve the incision toward the ulnar side of the forearm, without crossing the wrist flexion crease transversely.

Internervous Plane

• There is no true internervous plane for the volar approach to the wrist.
• No muscles are divided, though fibers of the abductor pollicis brevis and palmaris brevis muscles that cross the midline may occasionally be dissected.
• True anatomic dissection:
  • Key nerves are identified, dissected, and preserved.
  • The dissection plane lies between the median nerve and the flexor carpi radialis tendon.

Superficial Dissection

• Incise the skin flaps, then incise the subcutaneous fat.
• Divide the fibers of the superficial palmar fascia along the line of the incision.
• Retract the curved skin flaps medially to expose the insertion of the palmaris longus tendon into the flexor retinaculum.
• Retract the palmaris longus tendon medially to expose the median nerve, which lies between the palmaris longus and flexor carpi radialis tendons.
• Insert a blunt, flat instrument (e.g., a McDonald dissector) through the carpal tunnel, between the flexor retinaculum and the median nerve.
• Divide the retinaculum (carpal ligament) on the ulnar side of the nerve along its entire length.

Deep Dissection

• Identify the motor branch of the median nerve, located on the anterolateral side of the median nerve as it exits the carpal tunnel.
• If access to the volar wrist joint is needed:
  • Mobilize the median nerve and retract it radially, taking care not to stretch the motor branch.
  • Mobilize and retract the flexor tendons.
  • Incise the floor of the carpal tunnel longitudinally.
• The most convenient access to the volar aspect of the distal radius is through the distal part of the volar approach to the radius.

Approach Extension

Proximal Extension

The volar wrist approach can be extended to expose the median nerve and achieve the following:

• Extend the skin incision proximally, staying in the midline of the anterior forearm.
• Incise the deep forearm fascia between the palmaris longus and flexor carpi radialis muscles.
• Retract the flexor carpi radialis radially and the palmaris longus ulnarly, exposing the belly of the flexor digitorum superficialis in the distal two-thirds of the forearm.
• The median nerve adheres to the deep surface of the flexor digitorum superficialis, held there by a fascial layer. When the muscle is retracted, the nerve will move with it.

Distal Extension

• The volar wrist approach can be extended into a volar zigzag approach to any finger, providing full exposure of all palmar structures (volar approach to the flexor tendons).

Dangers

Structures at risk during the volar wrist approach include:

1. Palmar cutaneous branch of the median nerve:
   • Originates 5 cm proximal to the wrist.
   • Runs ulnar to the flexor carpi radialis tendon before crossing the flexor retinaculum.
   • The greatest risk of injury occurs if the skin incision is not curved toward the ulnar side of the forearm.
2. Motor branch of the median nerve:
   • Has significant anatomic variation.
   • Risk to the nerve is minimized by making the incision through the retinaculum ulnar to the median nerve.
3. Superficial palmar arch:
   • Crosses the palm at the level of the distal end of the extended thumb.
   • At risk when blindly dividing the flexor retinaculum, as the incision may extend too far distally.
   • Avoid injury by dividing the retinaculum under direct visualization along its full length.

References

• Surgical Exposures in Orthopaedics – 4th Edition
• Campbell’s Operative Orthopaedics – 12th Edition