Bruner Volar Zigzag Approach to the Digit

What it exposes. The Bruner volar zigzag approach gives extensile, safe exposure of the entire flexor tendon sheath and the digital neurovascular structures from the distal palm to the fingertip. It is the workhorse exposure for zone 2 flexor tendon repair, pulley reconstruction, selected digital fractures and drainage of flexor sheath infections. Primary indications:

• Zone 2 flexor tendon repair (the most common indication)
• Flexor tendon grafting or staged reconstruction
• A2 or A4 pulley reconstruction
• Digital phalangeal fracture fixation via a volar approach
• Flexor sheath infection drainage (pyogenic flexor tenosynovitis)
• Trigger finger release requiring extensive sheath exposure
• Volar plate repair or reconstruction Why this approach. The zigzag provides wide, extensile exposure of the flexor apparatus while minimising scar contracture across flexion creases. The oblique crossing of each crease allows broad flap elevation and access to both neurovascular bundles. It is preferred over the mid-axial approach whenever extensive volar work or bilateral neurovascular protection is required. Approach variants:
• Standard Bruner — a zigzag crossing the creases with mid-axial apices, used for most flexor tendon and sheath procedures.
• Extended proximal — continued into the palm or wrist, for combined zone 1 to 3 exposure.
• Limited window — fewer zigzags for focal exposure in selected pulley or fracture cases. Contraindications:
• Active infection with skin involvement over the planned incision
• Severe digital swelling precluding safe closure
• Previous volar scars that would compromise flap vascularity
• Isolated dorsal pathology that is better approached dorsally Alternative approaches:
• Mid-axial approach — a straight lateral incision along the mid-axial line elevating a single flap; it avoids crossing creases but gives poorer volar exposure, risks dorsal displacement of the neurovascular bundle, and is less versatile for extensive tendon or sheath work.
• Volar transverse incisions — limited exposure with a higher contracture risk.
• Combined approaches — for complex multi-structure injuries.

The approach works a safe corridor to the flexor sheath that lies between the paired radial and ulnar digital neurovascular bundles. Work proceeds from the skin zigzag through full-thickness flaps to the sheath, then between pulleys.

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Anatomy. The finger is built around the proximal, middle and distal phalanges; the flexion creases overlie the PIP and DIP joints, and the mid-axial line runs along the lateral aspect of each phalanx, equidistant from the volar and dorsal surfaces. The flexor apparatus comprises FDS (inserting on the middle phalanx) and FDP (inserting on the distal phalanx), constrained by five annular pulleys (A1 to A5) and three cruciate pulleys (C1 to C3). A2 (over the proximal phalanx) and A4 (over the middle phalanx) are biomechanically critical and prevent bowstringing; A1 overlies the MCP joint, A3 the PIP and A5 the DIP. Each digit carries paired radial and ulnar digital arteries and nerves running along the sides of the sheath, just volar to the mid-axial line, with the nerve lying dorsal to the artery; the common digital arteries bifurcate at the web spaces. The volar skin is thick with dense fibrous septa, and the subdermal vascular plexus lies immediately deep to the dermis, so it must be preserved by raising full-thickness flaps. Internervous plane. There is no true internervous plane. Dissection proceeds between the paired digital neurovascular bundles, which define the safe corridor to the flexor sheath; the bundles are the structures to be protected, not crossed.

Structures at risk, by layer

Extensile options. Extend proximally by continuing the zigzag into the palm with a Y-shaped limb at the distal palmar crease for zone 2 to 3 access, taking care to protect the common digital vessels and nerves. Extend distally to the fingertip when distal FDP repair or DIP work is required, preserving or reconstructing the A5 pulley if it is divided. Closure. Irrigate, achieve haemostasis, and close the skin without tension using everting mattress or simple interrupted sutures to prevent inversion; apices placed too volarly create a straight scar across the crease and a flexion contracture. Aftercare depends on the procedure: early protected motion after tendon repair reduces adhesions; a splint is used for fracture or pulley work; monitor digital perfusion and sensation and remove sutures at 10 to 14 days. Complications to avoid:

• Scar contracture across a flexion crease from poor incision geometry (apices too volar)
• Digital neurovascular injury from late identification or aggressive retraction
• Flexor tendon bowstringing from loss of A2 and A4 without reconstruction
• Wound edge necrosis from thin flaps or excessive undermining
• Infection in contaminated or infected cases

• Zone 2 flexor tendon repair — the principal indication; also primary or delayed repair across zones 1 to 3.
• Flexor tendon grafting or staged reconstruction with a silicone rod.
• A2 or A4 pulley reconstruction using a tendon graft or pulley advancement.
• Volar plate repair or reconstruction.
• Digital phalanx fracture fixation via the volar approach.
• Drainage of pyogenic flexor tenosynovitis.
• Extensive trigger finger release with pulley and sheath work.

The Bruner volar zigzag approach provides safe, extensile exposure of the flexor tendon sheath and digital neurovascular structures from the distal palm to the fingertip. The classic angled incisions cross each flexion crease obliquely at 45 to 60 degrees with apices precisely at the mid-axial points on each side of the digit. This geometry distributes scar tension away from the flexion crease and minimises the risk of a contracture that would limit digital flexion. Full-thickness skin flaps are elevated preserving the subdermal plexus, exposing the sheath from the A1 to the A5 pulley. The paired digital neurovascular bundles lie on the radial and ulnar aspects of the sheath and must be identified and protected throughout. The approach is the standard for zone 2 flexor tendon repair, pulley reconstruction, selected digital fractures and drainage of flexor sheath infections. A2 and A4 pulleys are preserved whenever possible because their loss produces bowstringing and loss of active flexion. No true internervous plane exists; dissection occurs between the paired neurovascular bundles.