Volar Palmar (Flexor) Approach to the Carpal Canal and Mid-Palm

What it exposes. The volar palmar (flexor) approach gives direct access to the carpal tunnel contents, the transverse carpal ligament (flexor retinaculum), the median nerve throughout its course in the hand, the flexor tendons in zones 3 and 4, and the mid-palmar space. It allows complete division of the flexor retinaculum under direct vision, inspection of the median nerve for hourglass constriction or tenosynovitis, and safe extension into the mid-palm while protecting the superficial palmar arch. No other single incision gives equivalent access to both the carpal canal and the mid-palmar flexor apparatus. Primary indications: - Open carpal tunnel release for idiopathic or secondary carpal tunnel syndrome

• Flexor tendon exploration and repair in zones 3 and 4 (mid-palm)
• Drainage of mid-palmar space infections and deep palmar abscesses
• Excision of mid-palmar masses (ganglia, lipomas, giant cell tumours of tendon sheath)
• Release of Dupuytren contracture involving the mid-palm
• Revision carpal tunnel surgery with nerve reconstruction or tenosynovectomy
• Combined procedures requiring access to both carpal tunnel and mid-palm Why this approach. It is the gold standard for open carpal tunnel release with direct nerve inspection, and it allows simultaneous access to carpal tunnel and mid-palmar pathology. The transverse carpal ligament is divided under direct vision, the median nerve is inspected, and the incision extends safely proximally into the forearm and distally along the flexor sheaths. Contraindications and alternatives. Active infection at the planned incision site, severe thenar wasting with fixed contracture, or a known high-risk transligamentous recurrent motor branch may favour an alternative strategy. Options include endoscopic carpal tunnel release (faster recovery, limited nerve visualisation, no mid-palm access), limited open (mini-incision) release (smaller scar, limited exposure for complex pathology), an extended carpal tunnel approach with forearm extension (for proximal median nerve pathology or Volkmann contracture), and combined volar and dorsal approaches for complex trauma involving both flexor and extensor surfaces. Position and landmarks. Supine, arm abducted 90 degrees on a hand table, upper-arm tourniquet at about 250 mmHg (or a forearm tourniquet for distal procedures), palm up, with loupe magnification (2.5x or 3.5x) and a headlight; a microscope is available if nerve reconstruction or complex tendon work is anticipated. WALANT (wide-awake local anaesthesia no tourniquet) allows intra-operative flexor tendon testing and is increasingly used globally. Palpable bony landmarks are the pisiform (TCL ulnar attachment), the hook of hamate (1 cm distal and radial to the pisiform), the scaphoid tubercle and the trapezium ridge (TCL radial attachments). Soft-tissue landmarks are the thenar crease (radial boundary - stay ulnar to it), the distal wrist crease (proximal limit), Kaplan cardinal line (hook of hamate to the radial border of the index MCP, near which the recurrent motor branch emerges), and the palpable flexor carpi radialis and palmaris longus tendons (palmaris longus is present in 80-85 percent of individuals).

Work down through the layers along the radial border of the ring finger axis, protecting the palmar cutaneous branch and the recurrent motor branch, then divide the transverse carpal ligament under direct vision to deliver the median nerve. The superficial palmar arch is the gatekeeper to the mid-palm and must be visualised before any distal extension.

View larger

Structures at risk, by layer

Complications

Extensile options. Extend proximally across the wrist crease in zig-zag fashion into the forearm (zone 5 flexor tendons, proximal median nerve, Volkmann contracture release) by incising the antebrachial fascia and developing the plane between flexor digitorum superficialis and profundus; the anterior interosseous nerve branch can be identified if needed. Extend distally along the flexor tendon sheath axis into the mid-palm and digits (zones 2-4 tendon repair, mid-palmar abscess drainage, mass excision), using a Brunner zig-zag for digital extension while protecting the digital neurovascular bundles - always identifying the superficial palmar arch first. For complex trauma or infection involving both flexor and extensor surfaces, combine with a separate dorsal approach; staged surgery may be required for severe contamination. Closure and post-operative care. Copious irrigation and meticulous haemostasis; document the median nerve appearance and the completeness of TCL release. Close the palmar aponeurosis loosely with absorbable suture (some surgeons leave it open), approximate the subcutaneous tissue, and close the skin with interrupted or running subcuticular sutures. Apply a bulky dressing with a plaster splint in neutral wrist position, elevate above heart level for 48 hours, and monitor median nerve sensation and motor function. Sutures are removed at 10-14 days with early scar massage from 3 weeks. Rehabilitation: splint and gentle finger range of motion for 0-2 weeks, active wrist and finger motion plus scar massage at 2-4 weeks, progressive strengthening at 4-6 weeks, and full activities by 6-12 weeks (desk job 2-4 weeks, manual work 6-12 weeks). Driving is usually safe at 2-4 weeks once grip is reliable.

• Open carpal tunnel release - the principal operation through this exposure; allows direct median nerve inspection and tenosynovectomy.
• Flexor tendon repair (all zones) - zones 3 and 4 in the mid-palm and carpal tunnel through the extensile distal limb.
• Hand infection drainage - mid-palmar and deep palmar space abscesses.
• Mid-palmar mass excision (ganglia, lipomas, giant cell tumour of tendon sheath) and Dupuytren contracture release involving the mid-palm.
• Revision carpal tunnel surgery with neurolysis or nerve wrapping, and combined carpal tunnel decompression with zone 3 flexor tendon repair.

Global practice and registry evidence. The volar palmar approach is used worldwide for carpal tunnel release, flexor tendon surgery and hand infection drainage, with convergent principles across the contemporary practice systems. Open release with direct nerve inspection remains the gold standard for complex, revision or teaching cases, while endoscopic release is accepted for straightforward idiopathic carpal tunnel syndrome in experienced hands (faster return to work but a slightly higher transient nerve injury rate). Carpal tunnel syndrome prevalence is 3-5 percent in the general population, higher in women and manual workers. Open carpal tunnel release has a greater than 85 percent long-term success rate, and incomplete TCL division is the most common cause of recurrence. In resource-limited settings, open release with basic instruments is the standard and the same incision principles apply; WALANT is increasingly used globally to reduce cost and allow intra-operative tendon testing.