1. Indications
Symptomatic carpal tunnel syndrome with characteristic nocturnal paraesthesia in the median nerve distribution that has failed at least 6 weeks of nocturnal wrist splinting and activity modification1. Decompression is also indicated where electrodiagnostic studies show moderate-to-severe compression, where there is objective sensory loss with two-point discrimination > 6 mm, or where there is wasting or weakness of the abductor pollicis brevis.
Population-based prevalence is approximately 3-4% in adults2, with women affected two to three times more often than men. Diabetes, pregnancy, hypothyroidism, and rheumatoid arthritis are recognised secondary causes that should be sought when bilateral symptoms are present.
2. Contraindications
Active local infection at the proposed incision site is an absolute contraindication. Pregnancy-related symptoms should be reassessed post partum, as most resolve spontaneously. Severe peripheral neuropathy from diabetes, alcohol, or chemotherapy may persist after decompression — patient counselling should manage expectations accordingly.
3. Relevant anatomy
The carpal tunnel is bounded radially by the scaphoid tubercle and trapezium, ulnarly by the pisiform and hook of hamate, and superficially by the transverse carpal ligament. It transmits the median nerve and nine flexor tendons (four flexor digitorum superficialis, four flexor digitorum profundus, and flexor pollicis longus). The classical wrist-flexion provocative test was first described by Phalen in his 1966 series of 654 hands3.
Critical anatomic variants to anticipate include the recurrent motor branch of the median nerve, which arises distal to the ligament in 50% of cases, transligamentous in 30%, and subligamentous in 20%. A persistent median artery and a high division of the median nerve (bifid median nerve) are present in approximately 8% and 2% of wrists respectively.
4. Patient positioning
Supine, with the affected arm extended on a hand table. An upper-arm tourniquet is inflated to 100 mmHg above systolic after exsanguination. Wide-awake local anaesthesia (1% lidocaine without adrenaline at the cutaneous incision site only, sparing the median nerve) is suitable for cooperative patients; brief regional anaesthesia is an alternative.
5. Approach
A 2-3 cm longitudinal incision is placed in line with the radial border of the ring finger, ulnar to the thenar crease. The incision should remain ulnar to the palmar cutaneous branch of the median nerve and proximal to Kaplan's cardinal line.
6. Key steps
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1. Skin incision and palmar fascia
Make a 2-3 cm longitudinal incision along the radial border of the ring finger axis. Divide subcutaneous tissue carefully, avoiding the palmar cutaneous branch of the median nerve which lies superficially radial to the incision. -
2. Identify and divide the transverse carpal ligament
The palmar fascia is incised in line with the skin incision. The transverse carpal ligament is identified as the firm white band running transversely beneath. Divide the ligament under direct vision from distal to proximal, staying ulnar to the median nerve. Confirm complete release by passing a closed Adson forceps along the ligament's course. -
3. Inspect the median nerve and tunnel contents
Inspect the median nerve for hourglass deformity, longitudinal vascular pattern, and any compressive lesion (lipoma, ganglion, anomalous lumbrical, persistent median artery). Avoid epineurotomy unless there is intraneural fibrosis. Tenosynovectomy is unnecessary in idiopathic disease but appropriate in inflammatory arthritis. -
4. Closure
Release the tourniquet and confirm haemostasis. Close skin only with interrupted 4-0 nylon or running subcuticular monofilament. Apply a soft compressive dressing without a rigid splint — early finger and wrist motion accelerates recovery.
7. Closure
Skin closure with interrupted 4-0 nylon, removed at 10-14 days. A simple bulky dressing is applied; a rigid splint is unnecessary and prolongs stiffness. Patients are encouraged to begin gentle finger and wrist motion the same day.
8. Aftercare
Sutures are removed at 10-14 days. Light desk-based activities resume at 1 week, driving at 2-3 weeks, and heavy manual work at 6-8 weeks. Pillar pain — a transient deep ache at the thenar and hypothenar eminences — affects up to 50% of patients and typically resolves within 3 months. Long-term follow-up at 5+ years shows durable relief in over 90% of patients4.
9. Complications
Major nerve injury occurs in less than 1% of open releases; the rate is reportedly higher with endoscopic technique in published systematic review data5. Recurrent motor branch injury produces thenar weakness; palmar cutaneous branch injury produces a painful neuroma. Incomplete release is the leading cause of persistent symptoms and revision surgery — confirmation of complete distal release is essential.
Postoperative complex regional pain syndrome (CRPS) is uncommon (< 1%) but devastating; early aggressive hand therapy is the mainstay of treatment. Surgical site infection is rare with simple cutaneous closure and good hand hygiene.
10. Evidence
Open and endoscopic techniques produce equivalent long-term symptom relief in randomised trials and Cochrane systematic review5. The choice of technique depends on surgeon experience, patient anatomy, and the presence of revision pathology. Open release remains the safer option in revision surgery, in patients with anatomic variants, and in trainees' hands. Recent narrative reviews summarise the current evidence base for clinical management of CTS.1
Long-term outcome data show that 88-95% of patients maintain symptom resolution at 5 years; revision rates are 3-5%, and most failures are attributable to incomplete release rather than scar reformation4.
For patients — plain-language summary
Open carpal tunnel release is a short outpatient operation in which the ligament that compresses the median nerve at the wrist is divided. It is performed under local anaesthesia through a small palm incision (about 2-3 cm) and takes around 10-15 minutes. Most patients are home within an hour and notice immediate relief of night-time symptoms. Light tasks (typing, light cooking) usually resume within a week; driving by 2-3 weeks; heavy manual work by 6-8 weeks. The scar typically remains tender for 6-12 weeks, then settles. Long-term outcomes are excellent, with over 90% of patients reporting lasting relief.
References
- Padua L, Coraci D, Erra C, Pazzaglia C, Paolasso I, Loreti C, et al. Carpal tunnel syndrome: clinical features, diagnosis, and management. Lancet Neurol. 2016;15(12):1273-1284. PubMed DOI
- Atroshi I, Gummesson C, Johnsson R, Ornstein E, Ranstam J, Rosén I. Prevalence of carpal tunnel syndrome in a general population. JAMA. 1999;282(2):153-158. PubMed DOI
- Phalen GS. The carpal-tunnel syndrome: seventeen years' experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg Am. 1966;48(2):211-228. PubMed
- Louie DL, Earp BE, Blazar PE. Long-term outcomes of carpal tunnel release: a critical review of the literature. Hand (N Y). 2012;7(3):242-246. PubMed DOI PMC
- Vasiliadis HS, Nikolakopoulou A, Shrier I, Lunn MP, Brassington R, Scholten RJPM, et al. Endoscopic versus open carpal tunnel release. Cochrane Database Syst Rev. 2014;1:CD008265. PubMed DOI