Mid-Axial Approach to the Digit

What it exposes. The mid-axial approach gives direct lateral access to the phalanx, the flexor tendon sheath and the PIP (and DIP) joint collateral ligaments. It is the workhorse exposure for phalangeal open reduction and internal fixation, PIP collateral ligament repair, volar plate work, flexor sheath exploration and excision of lateral masses. Why the mid-axial line (and not volar or dorsal). Placing the incision on the non-contact border keeps the scar off the working surface of the finger, preventing the painful scar contracture that would impair pinch and grasp. It also keeps the digital neurovascular bundle volar to the incision throughout, so the bundle is protected by remaining dorsal to it, and it reaches the flexor sheath without crossing the volar pulp. A dorsal approach is reserved for the extensor mechanism and dorsal lip fractures; a volar Bruner or straight incision is chosen for flexor tendon repair or volar plate/pulp work. Primary indications. - Phalangeal shaft, neck or base fractures requiring open reduction and internal fixation

• PIP joint fracture-dislocations needing collateral ligament repair or volar plate arthroplasty
• Collateral ligament injuries of the PIP or DIP joint requiring direct repair or reconstruction
• Excision of mucous cysts, giant cell tumours of tendon sheath or other lateral masses
• Flexor tendon sheath exploration or pulley release when a volar approach is undesirable
• Osteomyelitis or septic arthritis drainage of the phalanx or PIP joint Contraindications. Pathology requiring dorsal access (extensor mechanism, dorsal lip fractures), volar pulp or fingertip pathology, previous scarring or infection on the planned mid-axial line, and any case needing circumferential access.

Alternative approaches. Dorsal approach (extensor tendon repair, dorsal lip fractures, central slip injuries); Bruner volar zigzag (flexor tendon repair, volar plate exposure, pulley reconstruction); volar straight incision (limited volar access); lateral approach with nail-fold elevation (distal phalanx or nail-bed pathology).

Work down through the layers on the non-contact border, identifying and protecting the digital neurovascular bundle early, then develop one of the two interfascial planes — dorsal to Cleland or volar to Grayson — to reach the bone, sheath or joint.

View larger

Structures at risk, by layer

Extensile options. Extend proximally along the same mid-axial line into the web space to reach the metacarpal head and MP joint — identify and protect the transverse digital artery and the dorsal sensory branches at the web. Distal extension is limited by the nail fold; the incision may reach the lateral nail fold for the distal phalanx or DIP joint, but elevating the nail fold risks nail deformity. For circumferential access, a second mid-axial incision on the opposite border is useful for comminuted fractures or wide tumour margins — the two incisions must not meet at the tip or web, to avoid devascularising the skin bridge. Closure. Close skin with interrupted 5-0 or 6-0 nylon or absorbable monofilament, having confirmed the neurovascular bundle lies in its anatomical position without kinking or tension. The flexor sheath and periosteum are not closed routinely; any collateral ligament divided for access is repaired with 3-0 or 4-0 braided suture to bone or soft tissue. Release the tourniquet before closure to achieve haemostasis, and apply a bulky dressing with a dorsal plaster slab or aluminium splint holding the PIP joint in slight flexion. Aftercare. Strict elevation for 48 hours; active range of motion from 48-72 hours unless contraindicated; protective splinting for 3-6 weeks depending on the procedure; suture removal at 10-14 days; oedema control and scar massage from 3 weeks to prevent contracture. Pitfalls and complications. Digital neurovascular injury (less than 1 percent permanent deficit with careful technique); painful scar contracture on the contact surface if the wrong border is chosen; flexor tendon adhesion if the sheath is violated unnecessarily; PIP stiffness from prolonged immobilisation or scarring; nail deformity if extended too far distally; and web-space contracture if the transverse ligament is damaged. Suspected nerve injury recognised intra-operatively is explored immediately; established flexor adhesion is managed with early tenolysis if motion plateaus; PIP stiffness with dynamic splinting and hand therapy; and a functionally limiting scar with Z-plasty revision.

• Finger fracture fixation — open reduction and internal fixation of phalangeal shaft, neck or base fractures.
• PIP joint collateral ligament repair or reconstruction, and volar plate arthroplasty for fracture-dislocations.
• Flexor tendon sheath exploration, pulley release or pulley reconstruction.
• Excision of mucous cysts, giant cell tumours of tendon sheath or epidermal inclusion cysts.
• Drainage of septic arthritis or osteomyelitis of the phalanx or PIP joint; bone grafting of non-union; hardware removal. Fixation options through this approach. 1.5 mm or 2.0 mm lag screws for spiral or long oblique fractures; 1.5 mm or 2.0 mm plates for comminuted or transverse fractures; K-wires for simple fractures or temporary stabilisation; suture-anchor repair of collateral ligaments to bone; and volar plate advancement and reattachment for fracture-dislocations.