Carpal Tunnel Release - Open Technique

Indication. Open carpal tunnel release decompresses the median nerve by dividing the transverse carpal ligament (the flexor retinaculum). It is offered for clinically and electrodiagnostically confirmed carpal tunnel syndrome that has either failed a fair trial of conservative care or has features that make surgery the first option. Absolute indications

• Thenar atrophy with electrodiagnostic confirmation of severe CTS.
• Constant numbness in the median distribution unresponsive to splinting.
• Acute carpal tunnel syndrome from trauma, bleeding or burns requiring urgent decompression. Relative indications
• Failed conservative management after 3-6 months (night splinting, activity modification, a corticosteroid injection).
• Moderate-severe CTS on nerve conduction studies (distal motor latency greater than 4.5ms, sensory latency greater than 3.5ms).
• Recurrent symptoms after initial conservative success, or patient preference for definitive treatment. Contraindications
• Absolute: active infection in the surgical field; severe medical comorbidities precluding safe anaesthesia; a patient unable to comply with postoperative care.
• Relative: mild CTS responsive to conservative treatment; pregnancy (usually defer until postpartum unless severe); severe CRPS in the limb; pending litigation (relative). Open or endoscopic? Both are valid; the choice is surgeon and patient dependent. The open technique is taught here because it gives direct visualisation, guarantees a complete release, has a low learning curve, and can deal with any anomalous anatomy (persistent median artery, bifid nerve, mass lesion). Endoscopic release offers a smaller scar, less early pillar pain and a faster return to work, at the cost of a steeper learning curve, no direct visualisation of the thenar branch, and a contraindication in revision or anomalous cases.

• WALANT (wide-awake local anaesthesia, no tourniquet): 10ml of 1% lidocaine with 1:100,000 epinephrine injected 20-30 minutes before incision. The patient can actively move the fingers during the case, confirming a complete release and immediate symptomatic improvement. The historical fear of epinephrine causing finger necrosis has been debunked by modern evidence.
• Local anaesthesia with tourniquet: 1% lignocaine with 1:100,000 adrenaline, 5-10ml along the incision, with an upper-arm tourniquet at 250mmHg. Standard for most surgeons, giving a dry field.
• Regional block (axillary or supraclavicular): for anxious patients and longer postoperative analgesia; needs anaesthesia support.
• General anaesthesia: bilateral simultaneous cases, patient preference, or a medical condition requiring a controlled airway. Setup & positioning. Supine with the arm on a hand table, shoulder abducted 90 degrees (never more, to avoid brachial plexus stretch), elbow extended and forearm fully supinated. Upper-arm tourniquet (250mmHg), optional for WALANT. Standard hand tray: a number 15 blade, fine-toothed forceps, tenotomy scissors, a self-retaining retractor (Weitlaner or small Gelpi), a grooved director or MacDonald elevator, bipolar cautery, and 4-0 nylon or monocryl.

The goal is to decompress the median nerve by completely dividing the transverse carpal ligament while protecting three structures at risk - the palmar cutaneous branch, the thenar motor branch and the superficial palmar arch - and to confirm that release visually before a skin-only closure. The exposure (the incision and the dissection down to the ligament) is laid out as the first steps below; it is the heart of the operation, and is described in full on the volar approach to the carpal canal page.

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Rehabilitation | Phase | Timing | Activity | |-------|--------|----------| | Immediate | 0-2 weeks | Bulky dressing 3-5 days, then lighter. No routine splint. Immediate full finger ROM hourly; wrist ROM from day 3-5; light ADLs (eating, grooming, typing); elevation above heart 48h; avoid heavy grip or palm pressure; sutures out 10-14 days | | Early | 2-6 weeks | Scar massage from 3 weeks (5 minutes, three times daily); progressive wrist ROM; gentle putty strengthening from 3-4 weeks; return to desk work 1-2 weeks; avoid heavy manual work | | Intermediate | 6 weeks-3 months | Progressive strengthening; return to manual work at 6 weeks if tolerated; pillar pain resolving (90 percent by 3 months); grip still 10-20 percent down | | Long-term | 3-12 months | Thenar strength recovers gradually (permanent deficit in 20 percent of severe preoperative atrophy); grip returns to baseline by 6-12 months; scar matures by 6-12 months | Expected recovery timeline

• Night symptoms: resolve within days to 2 weeks in 95 percent.
• Daytime numbness: improves over 4-8 weeks, complete resolution in 85 percent by 3 months.
• Pillar pain: present in 30-40 percent, peaks 2-4 weeks, resolves in 90 percent by 3 months and 95 percent by 6 months.
• Grip strength: reduced 10-20 percent for 3-6 months, back to baseline by 6-12 months.
• Thenar strength: gradual recovery over 3-12 months; permanent weakness in about 20 percent of severe preoperative atrophy.
• Return to desk work 1-2 weeks; manual work 4-6 weeks; unrestricted activities 6-12 weeks. Success rates. Primary surgery gives 85-95 percent excellent or good results at one year (95 percent in mild-moderate CTS, 70-80 percent in severe CTS with atrophy where 20 percent have permanent thenar weakness). Revision surgery succeeds in 60-75 percent. Poor-outcome predictors include severe preoperative thenar atrophy, diabetes, a workers' compensation claim, symptoms lasting more than 10 months, age greater than 50, bilateral severe disease, and cervical radiculopathy (double crush).

Epidemiology. Carpal tunnel syndrome is the commonest compressive neuropathy of the upper limb worldwide. In a general-population survey of 2,466 responders (Atroshi, JAMA 1999), symptoms in the median distribution were present in 14.4 percent, clinically certain CTS in 3.8 percent and electrophysiological median neuropathy in 4.9 percent, giving a prevalence of clinically AND electrophysiologically confirmed CTS of 2.7 percent (95 percent CI 2.1-3.4) - roughly one in five symptomatic individuals has confirmed disease. There is a female predominance, a peak incidence at 40-60 years, and associations with obesity, diabetes, hypothyroidism, pregnancy, rheumatoid arthritis and repetitive or vibratory hand use. Anatomy of the carpal tunnel.

• Floor (dorsal): distal radius articular surface; scaphoid and lunate proximally; trapezium, trapezoid and capitate distally.
• Roof (volar): the transverse carpal ligament (flexor retinaculum) - a thick fibrous band 2-3cm long and 2-3mm thick, attaching to the scaphoid tubercle and trapezium radially and the pisiform and hook of hamate ulnarly.
• Walls: radial - scaphoid tubercle and trapezial ridge; ulnar - pisiform and hook of hamate.
• Contents: nine flexor tendons (flexor pollicis longus radially; four superficialis in a middle layer; four profundus deep) and the median nerve, which enters superficial and radial to the tendons and is the most superficial structure beneath the TCL - the structure compressed against the rigid roof in wrist flexion. Critical neural anatomy. The palmar cutaneous branch arises from the median nerve in the distal forearm 5cm proximal to the wrist crease, emerges between FCR and palmaris longus, passes superficial to the TCL and supplies the thenar skin - injured if the incision crosses the wrist crease. The thenar (recurrent motor) branch arises from the radial side of the median nerve about 1cm distal to the TCL edge and supplies abductor pollicis brevis, opponens pollicis and the superficial head of flexor pollicis brevis. The common digital nerves branch 1-2cm distal to the TCL, lie deep to the superficial palmar arch, and are visible at the base of the fat pad. Vascular anatomy. The superficial palmar arch crosses the palm 2-3cm distal to the TCL at Kaplan's cardinal line, formed by the ulnar artery with variable contributions from the median artery (5 percent) and radial artery (35 percent). A persistent median artery is present in 5-10 percent of people, travels with the median nerve through the tunnel, and can thrombose to cause acute CTS. Surface landmarks. Kaplan's cardinal line runs from the apex of the thumb-index web space to the hook of hamate and marks the superficial palmar arch (the distal safe-dissection limit). The thenar crease is the boundary between the thenar eminence and the palm; the incision stays 5mm ulnar to it. The ring-finger axis is the longitudinal line for the skin incision, avoiding the motor branch radially and the hypothenar neurovascular structures ulnarly. Classification - thenar motor branch variants (Lanz 1977). Lanz's overall scheme has four groups: Group I variations in the thenar branch course; Group II accessory distal branches; Group III high division of the median nerve; Group IV accessory proximal branches. The surgically critical Group I course (from Poisel's cadaver data) is:

Classification - severity (surgical perspective).

Guidelines, registries and global practice. | Body | Position | |------|----------| | AAOS (US) | Strong evidence that surgery is superior to non-operative care; recommends AGAINST routine adjuncts (internal neurolysis, epineurotomy, tenosynovectomy); routine post-op splinting not recommended | | NICE / BOA (UK) | Surgical decompression for confirmed moderate-severe CTS or failed conservative care; injection as a temporising option; simple complete release | | EFORT / European consensus | Complete division of the flexor retinaculum as definitive treatment; open and endoscopic equivalent for symptom relief | | AAHS / IFSSH | Endorse both open and endoscopic release; reserve endoscopic for surgeons with appropriate training; open preferred in revision or anomalous anatomy | This is a soft-tissue nerve decompression and is NOT captured by arthroplasty registries (NJR, AJRR, AOANJRR, SHAR). Antibiotic prophylaxis is NOT routinely indicated for clean elective release - meta-analysis shows no reduction in surgical-site infection; reserve antibiotics for high-risk patients (e.g. diabetes, immunosuppression) per local stewardship policy. Anaesthesia ranges from WALANT in office settings to local-plus-tourniquet, regional block or general anaesthesia by resource setting, and endoscopic uptake varies by region with equipment cost and training. Key evidence. Surgery is superior to splinting (Gerritsen 2002 RCT: surgery 80 percent versus splinting 54 percent success at 3 months, and 90 percent versus 75 percent at 18 months). Open and endoscopic release are equivalent for symptom relief and function (Vasiliadis 2014 Cochrane review), with endoscopic giving an earlier return to work. Internal neurolysis adds no benefit (Mackinnon 1991 RCT) and should not be performed. Local steroid injection gives useful but temporary relief and is mainly a diagnostic and temporising tool. Major societies (AAOS, NICE/BOA, EFORT) converge on the same message: complete TCL division alone is the global standard of care.