Orthopedic Surgery for Carpal Tunnel Syndrome 

Updated: Aug 13, 2018
Author: David A Fuller, MD; Chief Editor: Harris Gellman, MD 

Overview

Background

Carpal tunnel syndrome (CTS) is the most commonly diagnosed and treated entrapment neuropathy. The syndrome is characterized by pain, paresthesia, and weakness in the median nerve distribution of the hand. Surgical and nonsurgical treatments exist that can produce excellent outcomes for patients.[1]

In 1854, Paget first reported median nerve compression at the wrist after a distal radius fracture.[2] In 1880, Putnam presented the first series of patients with pain and paresthesia in the median nerve distribution of the hand.[3] In 1913, Marie and Foix described the pathology of median nerve compression underneath the transverse carpal ligament (TCL).[4] In 1933, Learmonth reported the first TCL release to treat median nerve compression at the wrist.[5] Since these early reports, much work has described the signs and symptoms of CTS, as well as its treatments.

An evidence-based clinical practice guideline on the management of CTS (see Guidelines) is available from the American Academy of Orthopaedic Surgeons (AAOS).[6]

For patient education resources, see Carpal Tunnel Syndrome.

Anatomy

The carpal canal is a fibro-osseous tunnel at the wrist through which nine flexor tendons and the median nerve pass.[7] The carpal bones define the dorsal aspect of the carpal canal and are shaped in a concave arch. The palmar aspect of the carpal canal is defined by the TCL, which bridges the two sides of the carpal arch. Intrinsic and extrinsic ligaments of the wrist and hand further stabilize the carpal bones. The carpal canal is narrowest at the level of the hook of the hamate, where the canal averages 20 mm in width.

The TCL attaches to the scaphoid tuberosity and trapezial crest on the radial side of the wrist, as well as to the pisiform and hook of the hamate on the ulnar side (see the image below). The TCL is 1.5 mm thick and 21.7 mm in length on average. Proximally, it is a continuation of the antebrachial fascia in the forearm, and distally, it attaches to the fibers of the midpalmar fascia.

Cross sections of carpal canal at levels of proxim Cross sections of carpal canal at levels of proximal and distal carpal rows. Transverse carpal ligament bridges carpal tunnel and is under tension.

The TCL is under tension and helps maintain the carpal arch. It serves as a retinacular pulley for the flexor tendons. Cutting the TCL increases the volume of the carpal canal. Cutting the TCL has also been postulated to alter the kinematics of the carpus, to risk bowstringing of the flexor tendons, and to decrease grip strength.

A combination of the lateral (C6-7) and medial (C8-T1) cords of the brachial plexus forms the median nerve. At the wrist and into the palm, the median nerve divides into terminal motor and sensory branches, with some anatomic variability. The variability is caused in part by the branching point of the recurrent motor branch (ie, extraligamentous or subligamentous).

An extraligamentous pattern, with a branching point distal to the TCL, is the most common. The recurrent motor branch can also divide from the median nerve underneath the TCL in a subligamentous fashion; it can then either wrap around the distal end of the TCL or pass directly through the TCL to innervate the thenar muscles. Other less common patterns, such as a branch point proximal to the TCL, exist as well. These variations can have major surgical implications.

The ulnar nerve is the other major motor and sensory nerve of the hand. The ulnar nerve does not pass through the carpal canal but instead goes through the Guyon canal, which is located adjacent to the carpal canal, at the wrist. Division of the TCL will change the morphology of the Guyon canal from triangular to ovoid.

Pathophysiology

The pathophysiology of CTS is typically demyelination. In more severe cases, secondary axonal loss may be present. The most consistent findings in biopsy specimens of tenosynovium from patients undergoing surgery for idiopathic CTS have been vascular sclerosis and edema.[8] Localized amyloid deposition in the tenosynovium also has been reported in persons with idiopathic CTS. Inflammation, specifically tenosynovitis, is not part of the pathophysiologic process in chronic idiopathic CTS.

Etiology

The etiology of CTS is multifactorial, with local and systemic factors contributing to varying degrees. Symptoms are a result of median nerve compression at the wrist, with ischemia and impaired axonal transport of the median nerve across the wrist.[9] Compression results from elevated pressures within the carpal canal.

Elevated pressures can develop within the carpal canal even though the canal is not a separate, closed compartment within the upper extremity. Direct pressure or a space-occupying lesion within the canal can increase pressure on the median nerve and produce CTS. Fracture callus, osteophytes, anomalous muscle bodies, tumors, hypertrophic synovium, and infection, as well as gout and other inflammatory conditions, can produce increased pressure within the carpal canal. Extremes of wrist flexion and extension also elevate pressure within the canal.

Compression of a nerve affects intraneural blood flow.[10, 11, 12] Pressures as low as 20-30 mm Hg retard venular blood flow in a nerve. Axonal transport is impaired at 30 mm Hg. Neurophysiologic changes manifested as sensory and motor dysfunction are present at 40 mm Hg. Further pressure increases lead to increasing sensory and motor block. At 60-80 mm Hg, intraneural blood flow ceases completely. In one study, the carpal canal pressures in patients with CTS averaged 32 mm Hg, compared with only about 2 mm Hg in control subjects.[10]

The double-crush syndrome, in which there is pressure on the median nerve at a second site (remote from the wrist), can further lower the median nerve's pressure threshold for producing symptoms of CTS. If a nerve is compressed at multiple sites, traction within the nerve with joint motion may be produced. In addition to pressure, traction or stretch has been demonstrated to produce alterations in intraneural circulation. Elongation of only 8% can impair venular flow, and all intraneural microcirculation can cease at 15% nerve elongation.

Many systemic conditions are strongly associated with CTS. These conditions may directly or indirectly affect microcirculation, pressure thresholds for nerve conduction, nerve cell body synthesis, and axon transport or interstitial fluid pressures. Perturbations in the endocrine system, as observed in individuals with diabetes and hypothyroidism and in women who are pregnant, are linked to CTS. Conditions affecting metabolism (eg, alcoholism, renal failure with hemodialysis, mucopolysaccharidoses) also are associated with CTS.

The international debate regarding the relation between CTS and the performance of repetitive motion and work is ongoing.[13, 14] The Occupational Safety and Health Administration (OSHA) has adopted rules and regulations regarding cumulative trauma disorders. Occupational risk factors—repetitive tasks, force, posture, and vibration—have been cited. However, the American Society for Surgery of the Hand has stated that the current literature does not support a causal relation between specific work activities and the development of diseases such as CTS.

Psychosocial and socioeconomic issues are increasingly being studied. In a study of risk factors for CTS in women, the greatest risk factor was found to be a previous history of another musculoskeletal complaint.[15] Perceptions of health and tolerance to pain also may influence the development of CTS.

The etiology of CTS and its relation to the workplace will continue to be better understood in the coming decades. It is already apparent that the etiology of CTS is multifactorial. Although work-induced repetitive trauma may not be the major cause of CTS, it may contribute in some way.

Epidemiology

CTS is common in the general population.[16] It has previously been reported with acute onset after trauma to the wrist; it has also been detailed as a gradual progression of symptoms typically occurring in women who are in the late middle-aged years of life. A new population at risk has been reported to be industrial workers whose hands and wrists are subjected to repetitive motion and trauma.[13, 14]

Controversy exists regarding the clinical and electrophysiologic findings necessary to diagnose CTS. Despite this controversy, several surveys have been conducted to determine the prevalence of CTS in the general population. In the Netherlands, the prevalence of undetected CTS was 5.8% in women and 0.6% in men.[16] In Sweden, the overall prevalence of CTS in the population was 2.7%. These prevalence rates were based on clinical and electrophysiologic criteria and probably represent minimum prevalence rate estimates.

In a Mayo Clinic study by Gelfman et al, temporal trends in CTS were assessed for incidence, surgical treatment, and lost time at work,[17] using Olmsted County residents as the study population. Between 1981 and 2005, a total of 10,069 residents were found to have been diagnosed with CTS (491 per 100,000 person years for women; 258 per 100,000 person years for men; 376 per 100,000 person-years combined).

Adjusted annual rates increased from 258 per 100,000 in 1981-1985 to 424 in 2000-2005. The average annual incidence of carpal tunnel release surgery was 109 per 100,000, and that for work-related CTS was 11 per 100,000.[17] According to the authors, the increase seen in this population corresponds to a national epidemic of CTS cases resulting in lost work days that began in the mid-1980s and lasted through the mid-1990s, but the cause for the increase is not yet clear.

Wolf et al studied the diagnosis of CTS in the United States military population from 1998 to 2006 and found the incidence to be 3.98 per 1000 person-years (compared with 1.5-3.5 per 1000 person-years in other regional or working-group populations studied).[18] In this military study, females had a significantly higher incidence of CTS than males, with an adjusted incidence rate ratio of 3.29.

CTS incidence was found to increase with age, with the age group 40 years or older having a significantly higher incidence.[18] Additionally, military rank was found to be an independent risk factor for CTS, with rates higher in senior officer and enlisted groups, suggesting that occupational requirements have an effect on CTS within the military.

Prognosis

Lasting relief of pain, numbness, and paresthesia can be expected in more than 90% of patients with CTS who are treated by means of open or endoscopic carpal tunnel release; patient satisfaction is high. The endoscopic technique is associated with a shorter interval before the patient returns to work and with less incisional pain.[19] The primary reason for a poor result is an error in diagnosis.

Jarvik et al compared surgical treatment (n = 57) with multimodality nonsurgical treatment (hand therapy and ultrasound; n = 59) for CTS without denervation.[20] Analyses showed a significant 12-month adjusted advantage for surgery in function and symptoms; there were no clinically important adverse events and no surgical complications. According to the authors, symptoms in both groups improved, but surgical treatment led to better outcome than nonsurgical treatment did.

Pomerance et al compared direct costs and results for surgical and nonsurgical care in 120 patients with electrodiagnostically proven CTS.[21] Follow-up averaged 13 months for the nonsurgical group and 12 months for the surgical group, with 32 patients in the former group electing to have surgery during the follow-up period. Cost averaged $3335 in the nonsurgery group and $3068 in the surgery group. The authors concluded that surgery should be considered as initial treatment of electrodiagnostically confirmed CTS because it provides symptom resolution with a favorable cost profile.

In a study of 950 open carpal tunnel procedures performed in 826 patients (age range, 21-100 years) at a high-volume orthopedic surgery center, Cagle et al found that the subjects showed significant improvements in symptom severity at 2 weeks after surgery and in functional severity at 6 weeks.[22]

In this study, the postoperative improvement was not affected by documented medical comorbidities, though patients with a medical comorbidity had a slightly higher (but statistically insignificant) risk of negative postoperative endpoints.[22] Improvement was slower in diabetic patients but was essentially equivalent at 6 weeks. In patients with workers' compensation insurance, symptom severity and hand function were significantly worse at baseline, 2 weeks, and 6 weeks, but no significant differences remained at 3 months.

 

Presentation

History

Acute carpal tunnel syndrome (CTS) can develop after a major trauma to the upper extremity (typically a distal radius fracture), a carpal dislocation, or a crush injury. Swelling, pain, and paresthesia in the median nerve distribution of the hand (palmar and radial) are observed.

In the more common idiopathic or chronic CTS, symptoms are more gradual in onset.[23] Pain and paresthesia in the median nerve distribution of the hand are common. Symptoms are often worse at night and can wake a patient from sleep. As the condition worsens, daytime paresthesia becomes common and is often aggravated by daily activities, such as driving, combing the hair, and holding a book or phone. Weakness can be present. With long-standing or severe cases of CTS, thenar atrophy is frequently observed.

Because of the motor and sensory disturbances, manual dexterity is diminished, and difficulty with such daily activities as buttoning clothes and holding small objects is often encountered. Pain and paresthesia can also occur proximally in the forearm, elbow, shoulder, and neck in as many as one third of patients. Pain and paresthesia in the hand are not always isolated to median nerve distribution but can involve the ulnar aspect or the entire hand.

Physical Examination

A thorough physical examination of the neck and upper extremity should be performed. Clinical tests to evaluate for CTS include sensory evaluations and provocative maneuvers that attempt to elicit signs or symptoms of median nerve compression at the wrist.

Sensory evaluations used in the workup include the following:

  • Semmes-Weinstein pressure monofilaments - Monofilaments of increasing diameter are pressed perpendicularly against the palmar aspect of each finger until the monofilament bends to determine the sensory threshold for each finger; values greater than 2.83 may be indicative of CTS
  • Vibratory sensibility - A 256-Hz tuning fork is struck against an object, causing it to vibrate, and the fork's prong is then placed against the patient's fingertips; the median and ulnar fingers of both hands are tested, and the test is considered positive if decreased sensation is perceived
  • Static and moving two-point discrimination - This is the minimum separation between two points (either static or moving) that can be perceived; failure to discriminate more than 6 mm (static) or 5 mm (moving) is a positive finding

Threshold tests (Semmes-Weinstein pressure monofilaments and vibratory sensibility) reflect gradual decreases in nerve function, but the innervation density tests (two-point discrimination) can remain normal until nearly all sensory conduction has ceased

Provocative tests include the following[24] :

  • Phalen wrist flexion test - The patient's elbows are placed on a table, with the forearms perpendicular to the table and the wrists flexed, and this position is held for 60 seconds; the test result is positive if numbness or paresthesia develops in radial-side digits
  • Tinel test - The examiner taps along the course of the median nerve on the volar aspect of the wrist; the test result is positive if paresthesia is elicited in the median nerve distribution
  • Carpal compression test - Direct application of pressure of 150 mm Hg or even pressure from both thumbs of the examiner is exerted on the patient's carpal canal and maintained for 30 seconds; the test result is positive if pain, numbness, or paresthesia develops in the radial-side digits
 

Workup

Imaging Studies

Wrist radiographs should not be routinely performed in patients with carpal tunnel syndrome (CTS), because too little useful information is obtained from these images.[25] Only 0.4% of routine wrist radiographs for CTS have been demonstrated to provide therapeutically significant findings.[25]

Patients with a history of systemic disorders, wrist trauma, arthritis, or abnormal findings (eg, limited motion) on physical examination for CTS are much more likely to have radiographic findings; Accordingly, use of wrist radiographs in these patients may be indicated.

Other Tests

Electrophysiologic diagnostic studies that may be considered include nerve conduction studies[26] and electromyography (EMG).

In the former, median motor and sensory latencies, as well as conduction velocities, are measured across the wrist. A sensory latency exceeding 3.5 ms or a motor latency exceeding 4.5 ms is considered an abnormal finding. Comparison with the contralateral hand, as well as with ulnar motor and sensory latencies and conduction velocities, can provide additional evidence supporting the diagnosis of CTS.

Distal compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes may be decreased in persons with CTS. Minimum F-wave latencies of the median nerve can be prolonged in individuals with CTS.

EMG must be performed with a clinical differential diagnosis in mind; the abductor pollicis brevis is the key muscle to evaluate. Positive findings in persons with CTS include sharp waves, fibrillation potentials, and increased insertional activity.

In the interpretation of electrophysiologic studies, it is important to remember that CTS is a clinical diagnosis. CTS is a constellation of signs and symptoms caused by the compression and slowing of the median nerve at the wrist. Electrophysiologic studies should not be used independently in making a diagnosis.[27]

Procedures

A catheter may be inserted directly into the carpal canal to measure pressure within the canal. This test is typically used to evaluate acute CTS and can help distinguish between median nerve contusion and compression. The figure of 30 mm Hg is a guide used to determine if the pressure is critically elevated, but physical examination and patient-specific factors can modify the critical pressure.

 

Treatment

Approach Considerations

Acute carpal tunnel syndrome (CTS) can be thought of as a compartment syndrome of the carpal canal. Decompression should be performed as soon as possible, provided that reduction of associated fractures or dislocations or removal of tight splints does not relieve the symptoms. Other medical and surgical factors may impact the opportunity to operate on an emergency basis, but relieving pressure on the median nerve is a priority in order to reduce the risk of permanent nerve injury.

Acute CTS can be diagnosed through history and physical examination alone. Electrophysiologic studies are not required. Sometimes, carpal canal pressure measurements are made to help support the diagnosis of acute CTS, with pressures greater than 30 mm Hg being consistent with the diagnosis.

Chronic CTS presents over time and is treated by means of both operative and nonoperative approaches. Patients with milder symptoms and shorter nerve conduction delays on electrodiagnostic studies respond most favorably to nonoperative treatment. Patients with more severe symptoms—duration longer than 1 year, weakness, atrophy, radial-side hand numbness, two-point discrimination greater than 6 mm, and longer nerve conduction delays—often do not benefit from nonoperative care. Surgical treatment is indicated if nonoperative treatment fails or if findings predictive of failure are noted.

In a systematic review assessing the effectiveness of surgical and postsurgical treatments for CTS, Huisstede et al found that surgical treatment appeared to be more effective than splinting or anti-inflammatory drugs plus hand therapy in the short, medium, or long term, but that there was strong evidence favoring local corticosteroid injection over surgery in the short term, as well as moderate evidence favoring manual therapy over surgery in the short and medium term.[28] No surgical treatment was found to be unequivocally more effective than another.

There are no specific contraindications for surgical treatment of CTS. Medical conditions should be stabilized before surgery. Pregnancy should be allowed to proceed to term, because CTS often resolves after the pregnancy.

Unrealistic expectations can influence surgical outcomes, and risk factors for poor outcomes should be sought preoperatively. Individuals with severe CTS should be cautioned that their numbness may persist, at least to some degree, despite a complete surgical release. Patients receiving worker's compensation have a lower return-to-work rate. A greater preference for improved strength preoperatively also has been associated with lower satisfaction.[29]

Medical Therapy

Steroid injection and wrist splinting have been used effectively in patients with milder symptoms of CTS.[21] A study reported complete relief of all symptoms in 76% of hands at 6 weeks after treatment, but by more than 12 months after treatment, the proportion of hands experiencing complete relief had deteriorated to only 22%.[30] Similar results were reported with steroid injection alone in a double-blind, placebo-controlled trial.[31]

Other nonoperative treatments have been proposed, but they have not been studied as rigorously; they include nonsteroidal anti-inflammatory drugs (NSAIDs),[32] vitamins (B complex), workstation redesign, ergonomic tool modification, acupuncture,[33] and yoga.

Ultrasound-guided platelet-rich plasma (PRP) infusions have been studied as well in this setting. In a systematic review including five studies, the bulk of the findings suggested that PRP infusion improved patients' clinical condition and was beneficial for those with mild-to-moderate CTS; however, further study is required before definite recommendations can be made.[34]

A systematic review of nonsurgical treatments for CTS by Huisstede et al found strong and moderate evidence for the effectiveness of oral steroids, steroid injections, ultrasound, electromagnetic field therapy, nocturnal splinting, the use of ergonomic keyboards compared with a standard keyboard, and traditional cupping versus heat pads. However, the only treatment for which long-term results were reported was steroids, and there was no evidence for the long-term effectiveness of these agents.[35]

A subsequent updated systematic review by Huisstede et al that examined studies of physical therapy and electrophysical modalities for CTS found moderate evidence for the effectiveness of myofascial massage therapy and several electrophysical modalities in the short term, as well as moderate evidence for radial extracorporeal shockwave therapy (ESWT) plus a neutral wrist splint, ESWT alone, and ultrasound in the medium term.[36] No randomized controlled trials on the long-term effects of physical therapy and electrophysical modalities were found by the authors.

Surgical Options

Open and endoscopic surgical techniques have been described for treatment of CTS. Both approaches are effective for chronic CTS. Potential benefits of endoscopy, including quicker functional recovery, must be weighed against the technique's increased cost and higher complication rate. The reliability of the open technique and the good visualization it provides continue to make it the preferred operation for many hand surgeons. Open release with an extended surgical incision is recommended for acute CTS.[37, 38, 39]

A realized goal of the less invasive endoscopic approach to carpal tunnel release is to return individuals to work sooner. To date, however, concerns over safety and cost have been an obstacle to wider acceptance and use of endoscopic techniques in this setting. It is hoped that this picture will be changed by the development of safer endoscopic methods and less invasive or nonoperative techniques that provide safe and lasting treatment for CTS.

Open Carpal Tunnel Release

General, regional, or local anesthesia can be used for open carpal tunnel release. The procedure is performed with a tourniquet inflated around the arm to control bleeding in the operative field. (See the videos below.)

Carpal tunnel release (part 1). Skin incision and retraction. Procedure performed by Deepak Kapila, MD, Broward Health, Fort Lauderdale, FL. Courtesy of BroadcastMed (http://ortho.broadcastmed.com/4229/videos/carpal-tunnel-surgery).
Carpal tunnel release (part 2). Exposure of palmar aponeurosis and transverse carpal ligament; entry into carpal tunnel. Procedure performed by Deepak Kapila, MD, Broward Health, Fort Lauderdale, FL. Courtesy of BroadcastMed (http://ortho.broadcastmed.com/4229/videos/carpal-tunnel-surgery).
Carpal tunnel release (part 3). Division of transverse carpal ligament, removal of tenosynovium, and release of median nerve. Procedure performed by Deepak Kapila, MD, Broward Health, Fort Lauderdale, FL. Courtesy of BroadcastMed (http://ortho.broadcastmed.com/4229/videos/carpal-tunnel-surgery).
Carpal tunnel release (part 4). Completion. Procedure performed by Deepak Kapila, MD, Broward Health, Fort Lauderdale, FL. Courtesy of BroadcastMed (http://ortho.broadcastmed.com/4229/videos/carpal-tunnel-surgery).

A longitudinal incision in the base of the palm is used (see the image below). The incision is made in line with the flexed ring finger. The intersection of this longitudinal line with the Kaplan line (a line parallel to the ulnar aspect of the extended thumb) marks the distal extent of the incision. Proximally, the incision ends a few millimeters distal to the distal wrist flexion crease.

Surgical incision for open carpal tunnel release. Surgical incision for open carpal tunnel release. Incision can be extended proximally across wrist flexion crease for more extended exposure.

Next, the subcutaneous fat is retracted radially and ulnarly, exposing the superficial palmar fascia. The superficial palmar fascia is divided sharply in line with the skin incision. Retractors are placed deeper to expose the transverse carpal ligament (TCL).

A blunt, curved hemostat clamp or similar instrument can be passed deep to the distal edge of the TCL to help confirm its position and to protect the contents of the carpal canal. The TCL is divided sharply along its ulnar aspect. Distally, the superficial palmar arch marks the end of the TCL and must be protected. Proximally, the ligament is transected to the level of the distal wrist crease under direct vision.

Blunt dissecting scissors are used to spread superficial and deep to the antebrachial fascia. Angled retractors are placed proximally under the skin flap so that the antebrachial fascia can now be divided for 2-3 cm proximally under direct vision, with the blunt scissors used partially open in a pushing fashion.

If visualization is poor, the skin incision may have to be extended proximally. If the incision must extend across the distal wrist crease, it should be angled.

Tenolysis, neurolysis, synovectomy, or reconstruction of the TCL is not routinely performed.

Before closure, the tourniquet is deflated, and hemostasis is obtained with bipolar electrocautery. No deep sutures are used. The skin is closed with 4-0 nylon. A soft, sterile dressing is applied.

Postoperative splinting has been recommended to prevent prolapse of nerve, entrapment of nerve in scar tissue, or tendon bowstringing. However, splinting has not been demonstrated to have any beneficial effect and can increase pain and scar tenderness.

A mini-incision approach to carpal tunnel release has been described, with good results reported.[40, 41]

Endoscopic Carpal Tunnel Release

Endoscopic carpal tunnel release may be performed with either a one-incision or a two-incision technique.[19, 42]  In both techniques, the first incision is made transversely, just proximal to the wrist flexion crease between the palmaris longus and the flexor carpi ulnaris (see the image and video below).

Surgical incisions for endoscopic carpal tunnel re Surgical incisions for endoscopic carpal tunnel release (one- and two-incision techniques). Precise location of incisions is critical and depends on individual anatomy.
Minimally invasive endoscopic carpal tunnel release. Procedure performed by Marc Tanner, MD, Bon Secours Health System, Greenville, SC. Courtesy of BroadcastMed (http://ortho.broadcastmed.com/4120/videos/minimally-invasive-endoscopic-carpal-tunnel-release).

In the one-incision technique, the blade assembly and viewing device are inserted into the carpal canal in an anterograde fashion through the incision. With the wrist in extension, the device is advanced to the distal edge of the TCL. Video images, ballottement, and transillumination can be used to confirm the position.

When correct positioning is assured, the cutting blade is elevated, and the device is withdrawn, cutting the distal half of the ligament. The device is then reinserted to inspect ligament division, and additional passes are made to complete the division of the remaining proximal portions of the ligament. The skin incision is sutured closed.

In the two-incision technique, the second incision is made transversely in the palm on a line bisecting the angle formed by lines drawn along the distal border of the fully abducted thumb and the third webspace (see above). Blunt dissection is performed in the palm to identify the superficial palmar arch, the common digital nerves, and the distal edge of the TCL. Following the axis of the forearm, a blunt, curved instrument is inserted into the carpal canal through the proximal incision to free soft tissues from the undersurface of the TCL.

A trocar-and-sheath assembly is passed in an anterograde manner from the proximal incision to the distal incision through the carpal canal. The fingers and wrist are then extended and secured in a custom holder. The trocar is removed, and the endoscope is inserted into the sheath through the proximal incision.

The distal half of the ligament is then divided with special upward and reverse cutting knives placed in the distal sheath while being viewed through the endoscope.

The endoscope then is removed and reinserted into the sheath through the distal incision, and the reverse cutting knife is inserted into the sheath through the proximal incision. By withdrawing the reverse cutting knife, the proximal half of the ligament is released. Skin incisions are sutured closed.

With either technique, if visualization is not satisfactory, the procedure should be abandoned and conversion to open carpal tunnel release initiated.

Complications

Complications are not common after either open or endoscopic carpal tunnel release.[43] Major complications with either approach can include nerve laceration, vessel laceration, and tendon laceration. Laceration of the palmar cutaneous branch of the median nerve with painful neuroma formation is reported to be the most common complication of open carpal tunnel release.

Incomplete release of the TCL is reported to be the most common complication of endoscopic carpal tunnel release. Loss of grip strength and tenderness of scars after open carpal tunnel release tend to resolve with time.

The general consensus among surgeons is that nerve injuries occur more frequently with endoscopic release than they do with open release. A 2014 meta-analysis of randomized, controlled trials lent support to this view.[44] Nerve injuries with the endoscopic technique are not necessarily related to the skill and experience of the surgeon but may be associated with the nature of the procedure, the anatomy of the carpal canal, and the device used.

 

Guidelines

Guidelines Summary

In February 2016, the American Academy of Orthopaedic Surgeons (AAOS) published an evidence-based clinical practice guideline for the management of carpal tunnel syndrome (CTS), which included the following recommendations[6] :

  • The routine use of magnetic resonance imaging (MRI) for CTS diagnosis is not recommended
  • Thenar atrophy, or diminished thumb muscle mass, is associated with CTS; however, a lack of thenar atrophy is not enough to rule out CTS
  • Do not use single results from common tests and maneuvers (muscle testing, nerve stress tests, etc.), and/or medical history and demographic information (sex/gender, ethnicity, co-morbidities, BMI, age, etc.) independently to affirm CTS diagnosis
  • Exercise and physical activity are associated with a decreased risk for developing CTS
  • Factors that may put patients at risk for CTS include obesity and, to a lesser extent, perimenopausal status, wrist ratio/index, rheumatoid arthritis, psychosocial factors, gardening, distal upper extremity tendinopathies, hand activity, assembly line work, computer work, vibration, tendonitis, and workplace forceful grip/exertion
  • The guidelines recommend splinting, steroids (oral or injection), the use of ketoprofen phonophoresis gel, and/or magnetic therapy; there is limited evidence to support therapeutic ultrasound or laser therapy for CTS symptoms
  • Surgery is recommended, when necessary, to release the transverse carpal ligament—the strong band of connective tissue that covers the top of the carpal wrist structure—to relieve symptoms and improve hand function
  • Surgical treatment of carpal tunnel syndrome should have a greater treatment benefit at 6 and 12 months as compared with splinting, nonsteroidal anti-inflammatory drugs (NSAIDs)/therapy, and a single steroid injection