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Carpal Tunnel Syndrome: A Review of Endoscopic Release of the Transverse Carpal Ligament Compared With Open Carpal Tunnel Release

Janz, Claudia; Hammersen, Stefanie; Brock, Mario

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This article is a review of endoscopic carpal tunnel release compared with open carpal tunnel release. In the first section, a brief account of anatomical and pathophysiologic aspects relevant for carpal tunnel surgery is given. It is followed by an overview of the different techniques presently available for endoscopic carpal tunnel release, comprising both monoportal and biportal approaches. Contraindications for endoscopic carpal tunnel release are discussed in detail. Results and complications of the endoscopic techniques are then compared with those of open carpal tunnel release. The article concludes that the development of new techniques, as well as increased knowledge of the contraindications, has made endoscopic carpal tunnel release as safe and effective as open carpal tunnel release.

Department of Neurosurgery, University Hospital Benjamin Franklin, Free University of Berlin, Berlin, Germany

Address correspondence and reprint requests to: Claudia Janz, MD, Neurochirurgische Klinik, Klinikum Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin.

Carpal tunnel syndrome is one of the most common nerve compression syndromes, and it affects up to 1% of the general population and 5% or more of the workforce in certain occupations that require repetitive use of the hands and wrists. 1 Nocturnal pain and paresthesia are early symptoms, whereas hypesthesia, thenar weakness, atrophy, and autonomic dysfunction occur in advanced cases. Open carpal tunnel release (OCTR) has been regarded as the effective standard surgical treatment of carpal tunnel syndrome for several decades.

In the late 1980s, a number of endoscopic carpal tunnel release (ECTR) techniques were developed. Although Okutsu et al. 2 and Chow 3 proposed a biportal approach, Agee et al. 4 developed a monoportal technique. Since their introduction, these new techniques generated not only excitement but also controversy. In the meantime, data from many clinical studies, including prospective randomized ones, are available for review. Proponents of ECTR claim a significant decrease in postoperative pain at the site of the incision and better cosmetic results with less scarring. Chow 5 explained the quicker recovery of grip and pinch strength by the preservation of the continuity between the lesser thenar and thenar muscles and by the decreased risk of bowstringing the flexor tendons. These advantages were found to result in an earlier return to work and activities of daily living as compared with open release of the transverse carpal ligament. 4–6

Critics, however, doubt the adequacy of median nerve decompression and fear increased complication and recurrence rates. 7 Their main concern is an increased risk of neural and vascular injuries, such as ulnar or median nerve transection and transient numbness of the fingers occurring in patients, especially those with anatomical variants.

Although the indications and threshold for surgery as such remain the same in both open and endoscopic techniques, selection of the proper surgical technique requires knowledge of the contraindications to the endoscopic procedure.

Limited incision techniques, a modification of standard OCTR, 8,9 and a distal (palmar) uniportal endoscopic technique 10 have been developed recently in response to apprehensions about the early ECTR techniques.

Many surgical steps previously associated with OCTR, such as exploration of the motor branch, epineurotomy or neurolysis, and flexor tenosynovectomy, are now considered unnecessary. 11

In this article, a brief account of anatomical and pathophysiologic aspects relevant for ECTR and an overview of available techniques will be followed by an analysis of the results and complications of the endoscopic techniques and by a comparison to the results of open techniques.

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RELEVANT ANATOMICAL ASPECTS

It is not within the scope of this article to fully describe the anatomy of the carpal canal and its contents. It should be kept in mind, however, that the palmar boundary of the carpal tunnel includes three continuous segments of the flexor retinaculum: the thin proximal segment composed of the thickened deep investing fascia of the forearm, the central transverse carpal ligament, and the distal portion, composed of an aponeurosis between the thenar and hypothenar muscles. The transverse carpal ligament (TCL) is defined by its bony attachments to the pisiform, the hook of hamate, the tuberosity of the scaphoid, and the ridge of the trapezium. 12

The structures at risk during endoscopic carpal tunnel release may be located at the proximal or distal border of the TCL and within the canal itself (Fig. 1).

FIG. 1.

FIG. 1.

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Proximal Border of the Ligament

The proximal entry to Guyon's canal is located just ulnar to the carpal tunnel at the level of the distal wrist flexion crease, which is the portal of entrance for most of the endoscopic techniques. Entry into Guyon's canal may injure the ulnar neurovascular bundle.

The palmar cutaneous branch usually leaves the median nerve in the distal third of the forearm and pierces the TCL to innervate the skin of the thenar eminence. Small branches may cross ulnar to the thenar crease. Although a transverse incision may jeopardize the nerve as it crosses the carpal creases, a longitudinal incision may injure the small terminal branches. Injury to the main nerve may result in numbness in a portion of the thenar eminence or in neuroma pain. Injury to a terminal branch can cause persistent local tenderness. 13

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Carpal Canal

In ECTR, the TCL should be divided along the line midway between the median nerve and the ulnar neurovascular bundle. The width of this “safe zone” may vary considerably from patient to patient. If the width is 3 mm or less, it may be difficult to ensure complete avoidance of these structures. 14

The hook of hamate is an important anatomical landmark in several endoscopic techniques. Anomalies such as a “floating” or “crooked” hook of hamate as well as fractures of the hook are therefore considered relative contraindications to ECTR. 15 Furthermore, it must be kept in mind that the ulnar artery may be located radial to the hook of hamate. 16

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Distal Border of the Ligament

Several of the anatomical structures at risk for being injured during ECTR are located near the distal edge of the TCL and may show considerable variations. According to Cobb et al., 17 the superficial palmar arch may be located between 2 and 26 mm from the distal edge of the TCL and is often hidden by the palmar fat pad. In an autopsy study, Rotman and Manske 18 found the superficial palmar arch to be located approximately 5 mm distal to the TCL.

The recurrent motor branch of the median nerve has an extraligamentous course in 46% of cases, travels subligamentously in 31% of cases, and travels transligamentously in 23% of cases. 19 The latter two variants are at risk for being damaged during ECTR.

The palmar fat pad consistently extends 2 to 3.5 mm proximal to the distal edge of the TCL along the ring finger axis 18 and may therefore obscure the distal edge of the ligament during ECTR. This could result in an incomplete release of the distal TCL. Phalen 20,21 already emphasized the importance of completely sectioning the distal extent of the roof of the carpal tunnel, which, according to Cobb et al., 12 is formed by a thickened aponeurosis between the thenar and hypothenar muscles.

A communicating branch between the median and ulnar nerves is present in 80% to 90% of individuals. When present, it may be close to the distal edge of the TCL and usually runs parallel to the superficial palmar arch. Its injury may result in paresthesia and pain of the long or ring fingers. 22

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RELEVANT PATHOPHYSIOLOGIC ASPECTS

Anatomically, there appear to be two locations in which median nerve compression is likely to occur at the wrist. The area of transition between the deep fascia of the forearm and the transverse carpal ligament is the most probable site of flexion-induced deformation of the median nerve, and may possibly be responsible for Phalen's sign. A second potential site for median nerve compression is at the level of the hook of hamate, where the canal is narrowest. 12

Although the carpal canal has an open end, Gelberman et al. 23 found significantly increased resting pressures in patients with carpal tunnel syndrome; these pressures increased further when the wrist was flexed or extended. Szabo et al. 24 demonstrated that, after repeated flexion and extendion of the wrists, return to resting pressures took longer in patients with carpal tunnel syndrome. Okutsu et al. 25 compared pressures in the carpal canal before and after ECTR and found postoperative pressures to be significantly lower in the resting position, with active grip, and with maximum passive wrist extension and flexion. Mean postoperative pressures in all positions were in the range of those measured in the control group, indicating that the TCL was probably completely released by ECTR. Conversely, extreme extension of the wrist, as in the Chow procedure, has been shown to cause significant compression of the ulnar nerve between the trocar and the distal ulna. 18

Critics argue that additional pressure on the median nerve by introduction of the trocar may represent a risk for the nerve. In a group of volunteers, Szabo et al. 24 were able to demonstrate that elevating the tissue fluid pressure in the carpal canal to 50 mm Hg and maintaining it for 45 minutes produced a conduction block of all group A-beta fibers of the median nerve. This was completely reversible when compression was terminated 10 to 20 minutes after a complete sensory block had occurred. Therefore, compression of the median nerve for approximately 5–10 minutes during ECTR is not likely to result in permanent nerve damage. However, one should be aware that Szabo's work was performed on healthy individuals.

Release of the TCL may result in an alteration of the carpal arch. Gartsman et al. 26 found an average increase of 13% in the width of the carpal arch after OCTR. As compared with OCTR, fewer soft tissue structures are released in ECTR. Viegas et al. 27 demonstrated that the transverse diameter of the carpal arch widens less after ECTR as compared with OCTR.

Kiritsis and Kline 28 discussed palmar displacement of the flexor tendons as a potential cause of weakness after carpal tunnel release. After open transection of the transverse carpal ligament in a cadaveric model, they found tendon excursion by wrist motion to be increased by 26% for the flexor digitorum profundus and by 18% for the flexor digitorum superficialis tendons. After ECTR, tendon excursion by wrist motion was found to be increased by 21% for the flexor digitorum profundus and by 15% for the flexor digitorum superficialis tendon. The differences between both methods were not significant.

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TECHNIQUES AVAILABLE FOR ENDOSCOPIC CARPAL TUNNEL RELEASE

It is beyond the scope of this article to give a full description of all endoscopic techniques presently available for ECTR. Only the most important ones are outlined to give an impression of the different approaches (Figure 2). A basic distinction is made between monoportal and biportal techniques. However, most of the literature on ECTR is related to the techniques of Chow 3,5 or Agee. 4,6

FIG. 2.

FIG. 2.

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Monoportal Techniques With Proximal Entry

Agee Technique (Second-Generation Device)

After tourniquet control and regional block or general anesthesia, a 2-cm skin incision is placed in the wrist flexion crease between the flexor carpi ulnaris tendons. A synovial elevator followed by a probe inserted through a distally pediculated U-shaped incision in the forearm fascia helps define the proximal-to-distal path along the palmar-ulnar aspect of the carpal tunnel. With the device aimed at the ring finger and with the wrist extended, the blade assembly is inserted along the same path. The device (3-M Health Care, St. Paul, MN) consists of a pistol grip handpiece with an integrated trigger mechanism comprising a blade assembly specifically designed to be inserted across the carpal tunnel. A window near the tip of the blade assembly serves to make the transverse carpal ligament visible. Once the distal edge of the ligament is clearly identified, the trigger is pulled to elevate the blade. The transverse carpal ligament is incised on withdrawal of the device. Additional passes may be necessary for complete release of the ligament, with endoscopic control permitting visualization of its cut edges. 6

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Okutsu Technique

A transparent cannula is inserted into the carpal canal for visualization of the ligament. As a second step, a hook knife is inserted into the carpal canal adjacent to the cannula. Pulling the knife proximally with one hand, the transverse carpal ligament is released while the endoscope is operated with the other hand. 2

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Menon Technique

The carpal canal is dilated to a diameter of 7 mm. A plastic cannula is advanced into the carpal canal, and a needle is inserted into the cannula through the skin to identify the distal margin of the transverse carpal ligament. The knife is then pushed through the cannula from proximal to distal, with the endoscope following the knife so that the surgeon can observe the procedure endoscopically. 29

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Monoportal Technique With Distal Entry

Mirza Technique

A 1.5-cm incision is made in the palmar region, so as to identify the superficial palmar arch, the distal edge of the transverse carpal ligament, and flexor tendons. Two longitudinal lines representing the location of the median nerve and the ulnar neurovascular bundles are drawn proximal to the wrist crease. An obturator-dissector-cannula system is placed against the transverse carpal ligament and advanced proximally into the carpal canal to the wrist flexion skin crease. After removal of the obturator, a knife/sleeve device attached to a 4-mm endoscope is advanced proximally through the slotted cannula, dividing the ligament under direct visualization to a point proximal to the wrist flexion crease. 10

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Biportal Techniques

Extrabursal Chow Technique

While the patient is supine, the arm is abducted and placed on a hand table. The procedure is performed under local anesthesia (1% lidocaine). An 8-mm incision is made ulnar to the tendon of the palmaris longus muscle in a skin fold approximately 1 cm proximal to the distal wrist crease. The superficial forearm fascia is exposed and split longitudinally. A blunt curved dissector is then inserted beneath the ligament. If correctly placed, the dissector “palpates” the deep aspect of the ligament. Then the trocar and the working cannula are inserted beneath the ligament and gently advanced toward the third web space. If the instruments are properly located in the carpal tunnel, lifting the instruments will lift the entire arm. The wrist is then placed on a special hand support in extension (Figure. 3). When the tip of the trocar reaches the palmar region, it can be felt through the skin. A second small incision is then made in one of the palmar folds, and the trocar and working cannula are advanced further through this skin incision. The trocar is then removed, and the endoscope is introduced. The transverse fibers of the ligament can be identified through the slit in the “upper” part (“12 o'clock”) of the working cannula. Sliding a blunt hook along the transverse ligament through this slit causes a “washboard sensation.” The ligament is released by means of differently shaped knives. When split, the ligament “falls apart,” widening the carpal tunnel. The protrusion of palmar fatty tissue into the working cannula proves that complete splitting has been achieved. After withdrawal of the instruments, both incisions are closed by nonresorbable sutures. 5

FIG. 3.

FIG. 3.

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Brown Technique

A 2-cm transverse incision is made between the flexor carpi ulnaris and palmaris longus tendons, just proximal to the crease of the wrist in flexion. A 4×5 mm rectangular, distally pediculated flap is created in the transverse carpal ligament. Blunt dissection is used to free the synovial surface from the undersurface of the ligament. A second transverse incision is performed at the intersection of a line drawn along the metacarpal of the ring finger and the Kaplan cardinal line. The superficial palmar arch, common digital branches of the median nerve, and the distal edge of the transverse carpal ligament are identified. With the wrist placed in 30° extension, the trocar and the sheath assembly are passed through the proximal incision and the carpal canal, exiting through the distal incision. The distal antebrachial fascia and the distal edge of the ligament are cut under direct vision; the remaining parts of the TCR are cut under endoscopic vision, using an upward-cutting triangular and a retrograde-cutting hooked knife. 30

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RESULTS OF ENDOSCOPIC CARPAL TUNNEL RELEASE (CURRENT REVIEW OF THE LITERATURE)

Since Okutsu 2 and Chow 3 introduced their endoscopic techniques in 1989, a highly emotional controversy has evolved. Enthusiastic reports by the proponents of ECTR emphasizing lower postoperative morbidity, quicker recovery of strength, early return to previous activities, and a reduced period of disability were in opposition to case reports on major complications such as ulnar and median nerve transections. Brown et al. 30 reported that although functional recovery was achieved earlier, the endoscopic techniques resulted in higher complication rates as compared with the open technique. Opponents of the new techniques considered the general advantages to be outweighed by single cases of severe complications. In the following years, several efforts were made to improve the safety of the endoscopic devices (Table 1).

TABLE 1

TABLE 1

In 1990, feedback from surgeons led the manufacturer of the original Agee Carpal Tunnel Release System (3-M Health Care, St. Paul, MN) to withdraw the device from the market. Surgeons called for a redesign of the blade assembly to improve the blade elevation mechanism and to allow continuous viewing of the point of entry of the blade into the transverse carpal ligament. This improved device was investigated in a prospective multicenter study comprising 1,049 procedures in 988 patients presented by Agee in 1995. 6 In this study, conversion to an open procedure became necessary in 2.5% of the cases, and to a different endoscopic system in 0.2%. In 0.9% of the cases the surgeon elected to add a second incision at the distal end of the ligament. The complication rate was 1.8%. Only 2 of 11 cases with abnormal postoperative sensation were permanent. Agee found no significant association between the type of anesthesia and complications.

In the original Chow 3 procedure it was necessary to enter and exit through the ulnar bursa. This technique, developed in cadaveric studies, aimed at taking profit of a smaller risk of entering Guyon's canal. However, there was always some bursal tissue obstructing the endoscopic view of the proximal transverse carpal ligament. In 1993, Chow 5 presented a modification of this technique consisting of an extrabursal insertion of the slotted cannula to provide better visualization of the entire ligament. In 1994, 31 he published data on 1,154 cases. Early complication rate was 0.26%, including one incomplete release of the ligament and two transient ulnar nerve palsies. Late complication rate was 0.26% (3 recurrences). In 1996, Nagle et al. 32 compared the results of Chow's transbursal and extrabursal techniques. He found an overall complication rate of 11% for the transbursal technique compared with 2.2% for the extrabursal technique. A recurrence occurred in 7.3% of the cases subjected to the transbursal technique and in 1.3% following the extrabursal technique.

Wheatley 33 described a simple technique for identifying the distal margin of the transverse carpal ligament during monoportal endoscopic carpal tunnel release: the tip of the elevator is palpated through the skin of the palmar region at the point where it passes beyond the distal margin of the TCL. This spot is marked with a surgical pen. Thereafter a 27-gauge needle is introduced perpendicular to the plane of the palm and visualized through the endoscope. The aim of this method is a reliable division of the distal portion of the TCL while minimizing the risk of injury to the palmar arch and to the common digital nerves. Menon 29 uses a similar technique.

Because several of the anatomical structures at risk are located near the distal border of the transverse carpal ligament (see above), Mirza 10 developed a uniportal palmar technique permitting direct visualization of the superficial palmar arch, the distal edge of the transverse carpal ligament, the median nerve, and the flexor tendons. He reported on a follow-up study of 475 patients and found one case of transient neuroapraxia of the communicating branch of the ulnar nerve (0.2%), one case of mild reflex sympathetic dystrophy, and 1 blade failure in a prototype device. The rate of conversion to open CTR was 2%. 34

In 1998, Nakamichi and Tachibana 14 suggested ultrasonographically assisted ECTR. They drew attention to the “safe zone” between the median nerve and the ulnar neurovascular bundle, the width of which should be greater than 3 mm for safe division of the transverse carpal ligament. They recommended OCTR in individuals with a narrow safe zone (3 mm or less) and identification of these cases by preoperative ultrasound.

Chow 31 reported on the results of an ECTR cadaver workshop held in 1992, collecting the data of 10,640 carpal tunnel cases. He noted that surgeons who had performed fewer than 25 operations had a complication rate of 5.6% as compared with less than 1% for those who had performed more than 100 procedures. A higher complication rate for less experienced surgeons is not unique to ECTR.

Thus, improvement of the endoscopic techniques led to a marked reduction of complication rates. Furthermore, as with any new surgical procedure, reports of complications helped in defining indications and contraindications of ECTR, as illustrated by the following two examples:

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Injury to the Median or Ulnar Nerve

As a consequence of the limited exposure (inherent to endoscopic procedures), there has been concern about potential injury to neural structures. It was discussed that the “cost” of a single nerve injury may well outweigh the financial benefits resulting from a larger number of patients returning to work sooner. 35

Nath et al. 35 reported on a case of ulnar nerve transection in which the nerve was found to be injured at the site of the proximal incision in a patient undergoing the two-portal Chow technique under intravenous regional anesthesia. Del Pinal et al. 36 described total ulnar nerve transection caused by ECTR under general anesthesia according to Chow. Two different ways of lacerating the ulnar nerve in the course of ECTR were discussed—inadvertent entry into Guyon's canal instead of the carpal canal and looping of the ulnar neurovascular bundle.

Dheansa and Belcher 37 (1998) added two cases of median nerve injury during ECTR under general anesthesia using the technique of Agee.

In no case was there any technical problem with the procedure itself. Interestingly, in all four cases the operation was performed under general or regional anesthesia. There are no reports on median or ulnar nerve transection under local anesthesia.

Atroshi reported on a prospective study of 255 ECTRs performed using the Chow technique and found 5 cases of postoperative digital neuroapraxia, 3 of which were transient. Again, all these cases had been performed under general or regional anesthesia.

It is therefore recommended that ECTR be performed under superficial local anesthesia, thus enabling the patient to report any pain radiating into a finger in case the trocar comes close to the ulnar or to the median nerve or to one of its distal branches.

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Injury to the Flexor Tendons

Scoggin and Whipple 38 described the case of a patient with arthritic contractures who was unable to fully extend the wrist and metacarpophalangeal joints and in whom the tendon of the flexor digitorum superficialis muscle to the ring finger was nearly cut during ECTR. The procedure had to be converted to OCTR, and it was found that the flexor digitorum superficialis tendon was tethered over the arthroscopy sheath. Because of this, severe wrist and hand arthritis with limited extension of the wrist and fingers should be considered as a contraindication to ECTR.

Careful observance of the contraindications, including preoperative screening of the patients by an experienced endoscopic surgeon, is important to keep the complication rate low. For evident ethical reasons, this cannot be proved by a randomized study.

Atroshi 39 described a complete relief of symptoms at a 6-month follow-up in 83% of the patients and satisfaction with surgery in 89% (Chow technique). Brown et al. 30 performed a prospective randomized study comparing OCTR and ECTR (Brown technique) and found relief of pain and paresthesia in 98% of the patients operated on using the open technique and in 99% of the patients operated on using the endoscopic technique. Satisfaction of the patients with the procedure was 84% in the OCTR and 89% in the ECTR group. Elmaraghy and Hurst 40 also found that less than 2% of their patients were still symptomatic 10 weeks after ECTR using the Agee device. These studies indicate that ECTR is as effective as OCTR.

Most studies of ECTR report an earlier return to work as compared with OCTR. Chow 41 found 85.9% of his first 149 patients returned to work within 4 weeks of surgery. Agee et al. 4 described a median time for patients with unilateral surgery to return to work of 25 days for ECTR as compared with 46.5 days for OCTR. Atroshi 39 reported a median time of 17 days until return to work when the biportal Chow technique was used. In 240 cases treated by the monoportal palmar technique Mirza et al. 10 found a median interval of 14 days for return to work and recovery of full function. Most studies demonstrated that patients with workers' compensation took much longer to return to work than did those without workers' compensation. Elmaraghy et al. 40 reported a 22.2-day interval for non-workers' compensation cases as compared with 40.8 days for workers' compensation cases when the Agee 6 device was used. There was no difference regarding the return-to-work intervals between ECTR and OCTR for this subgroup of patients. 4

In 1996, Nagle 42 presented a review of the ECTR literature comprising the results of nearly 17,000 ECTRs. The overall complication rate averaged approximately 1.8%. The incidence of neurovascular complications and reflex sympathetic dystrophy was even lower. Most of the neural complications were transient neuroapraxias resolving within the first 6 months. Later studies, using the extrabursal Chow technique or the second-generation Agee device and including larger numbers of patients, revealed low complication rates that compared favorably with those of OCTR. Madonna and Rigoni 43 (1991) studied 600 patients who underwent OCTR. No neural lesions were found. Painful scars and the so-called pisotriquetral syndrome, causing local wrist pain, were the most frequent complications, resulting in an overall complication rate of 11.5%. In a randomized prospective trial comparing open and extrabursal ECTR, Erdmann 44 found an incidence of complications of 3.7% in the endoscopic series and 13.5% in the open series. OCTR did not cause neural lesions but did cause problems related to scar formation in 11.5% of patients.

In 1991, Kuschner et al. 45 reviewed 14 studies of OCTR comprising a total of 3,035 hands operated on. Hypertrophic painful scars were reported in 8 of the 14 studies. The average incidence of symptoms was 6% (0%–23%). Persistence of symptoms was identified in 4% (0%–57%) in half the studies included. The mean rate of superficial infections was 0.95% (0%–6%). Nerve injuries amounted to 0.8%, including injuries of the palmar cutaneous nerve, the thenar motor branch, and the common digital nerves.

These studies show that OCTR is not wholly free of complications as frequently claimed by its proponents. Even the rate of nerve injuries is not lower for OCTR than that found in recent ECTR studies.

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SELECTION OF THE APPROPRIATE TECHNIQUE

The proponents of ECTR disagree about contraindications. Chow recommends the open procedure whenever extensive neurolysis or tenosynovectomy is required, if extension of the wrist or fingers is limited, or whenever a lesion with a mass effect is suspected in the carpal canal. In contrast to Agee, Chow did not exclude patients with a history of wrist injury, previous wrist fractures, or rheumatoid disease. He performed ECTR even in some patients with recurrent carpal tunnel syndrome 5. Agee, 4 on the other hand, excludes all patients with generalized peripheral neuropathy, diabetes mellitus, thyroid disease, anatomical wrist and hand abnormalities (including previous dislocation fractures), inflammatory joint disease, a history of median nerve injury from trauma (including contusions or fractures of the distal radius or wrist joint), previous wrist surgery, vasospastic disorders such as Raynaud's disease or sympathetic dystrophies, psychiatric disorders, chronic renal disease requiring dialysis, previous carpal tunnel release, and thenar weakness requiring tendon transfer to support thumb opposition. In 1996, Jebson and Agee 15 described an anomaly of the hook of hamate as a further contraindication. With increasing experience, the following strategy was suggested:

  • In cases of rheumatoid arthritis, ECTR is technically feasible but contraindicated because of its high risk of aggravating the inflammatory process at the wrist joint.
  • Patients with previous wrist trauma are divided into two subgroups. Those who develop carpal tunnel syndrome several weeks after a trauma (including fractures of the distal radius) can usually undergo endoscopic surgery if the wrist can be extended without pain or gradual limitations. Those with symptoms of median nerve damage at the time of injury and those with limited extension of the wrist joint as well as those with previous wrist surgery are excluded from the endoscopic procedure.
  • In cases of recurrent tenosynovitis or other types of palmar inflammation, insertion of the trocar is difficult and often painful. Because neurolysis may also be necessary in these cases, OCTR is the method of choice.
  • In pregnant women with an excessive gain of weight and edema, synovial swelling should be suspected, which makes these patients candidates for OCTR.
  • Dupuytren's contracture or previous hand surgery may affect the exit area of the trocar and limit wrist and finger extension. ECTR is contraindicated in these cases.
  • Because hemostasis can only be achieved by compression, the endoscopic technique is not indicated for patients on anticoagulant therapy.
  • If marked involvement of the thenar branch is found, open exploration may be necessary.
  • Chronic renal failure requiring dialysis does not constitute a contraindication to the endoscopic procedure as long as it does not endanger the hemodialysis shunt.
  • Whenever the patient insists on having general anesthesia, ECTR release is contraindicated (see above).
  • A suspected lesion with a mass effect in the carpal canal or a severe abnormality of muscle, tendon, or vessel in this area are also regarded as contraindications.
  • In all other cases, both OCTR and ECTR can be used.
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CONCLUSION

The development of the new endoscopic techniques for carpal tunnel release is in part attributable to patients' demands as a result of reports in the mass media. Confronted with such demands, surgeons may be afraid of losing the patient to another surgeon if they do not offer ECTR. The risk of complications reported in the first years after introduction of the new techniques has decreased to levels comparable to those of OCTR. The literature shows that endoscopic devices and techniques presently available as well as increased knowledge of the contraindications have made ECTR as safe and effective as OCTR. Faster functional recovery and an earlier return to work are achieved by ECTR in uncomplicated idiopathic carpal tunnel syndrome.

In experienced hands ECTR may be considered the method of choice in the surgical treatment of the carpal tunnel syndrome.

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REFERENCES

1. Palmer DH, Paulson JC, Lane-Larsen CL, et al. Endoscopic carpal tunnel release: a comparison of two techniques with open release. Arthroscopy 1993; 9:498–508.
2. Okutsu I, Ninomiya S, Takatori Y, et al. Endoscopic management of carpal tunnel syndrome. Arthroscopy 1989; 5:11–8.
3. Chow JCY. Endoscopic release of the carpal ligament: a new technique for carpal tunnel syndrome. Arthroscopy 1989; 5:19–24.
4. Agee JM, Mc Carroll HR, Tortosa RD, et al. Endoscopic release of the carpal tunnel: A randomized prospective multicenter study. J Hand Surg [Am] 1992; 17:987–95.
5. Chow JCY. The Chow technique of endoscopic release of the carpal ligament for carpal tunnel syndrome: four years of clinical results. Arthroscopy 1993; 9: 301–14.
6. Agee JM, Peimer CA, Pyrek JD, et al. Endoscopic carpal tunnel release: a prospective study of complications and surgical experience. J Hand Surg [Am] 1995; 20:165–71.
7. Deune EG, Mackinnon SE. Endoscopic carpal tunnel release. The voice of polite dissent. Clin Plast Surg 1996; 23:487–505.
8. Biyani A, Downes EM. An open twin incision technique of carpal tunnel decompression with reduced incidence of scar tenderness. J Hand Surg [Br] 1993; 18:331–4.
9. Bromley GS. Minimal-incision open carpal tunnel decompression. J Hand Surg [Am] 1994; 19:119–20.
10. Mirza MA, King ETJ, Tanveer S. Palmar uniportal extrabursal endoscopic carpal tunnel release. Arthroscopy 1995; 11:82–90.
11. Innis PC. Endoscopic carpal tunnel release. J South Orthop Assoc 1996 Winter; 5:281–91.
12. Cobb TK, Dalley BK, Posteraro RH, et al. Anatomy of the flexor retinaculum. J Hand Surg [Am] 1993; 18:91–9.
13. Taleisnik J. The palmar cutaneous branch of the median nerve and the approach to the carpal tunnel. An anatomical study. J Bone Joint Surg 1973; 55A:1212–7.
14. Nakamichi K, Tachibana S. Distance between the median nerve and ulnar neurovascular bundle: Clinical significance with ultrasonographically assisted carpal tunnel release. J Hand Surg [Am] 1998; 23:870–4.
15. Jebson PJ, Agee JM. Carpal tunnel syndrome: unusual contraindications to endoscopic release. Arthroscopy 1996; 12:749–51.
16. Cobb TK, Carmichel SW, Cooney WP. The ulnar neurovascular bundle at the wrist. A technical note on endoscopic carpal tunnel release. J Hand Surg [Br] 1994; 19:24–6.
17. Cobb TK, Knudson GA, Cooney WP. The use of topographical landmarks to improve the outcome of Agee endoscopic carpal tunnel release. Arthroscopy 1995; 11:165–72.
18. Rotman EB, Manske PR. Anatomic relationships of an endoscopic carpal tunnel device to surrounding structures. J Hand Surg [Am] 1993; 18:442–50.
19. Lanz UL. Anatomical variations of the median nerve in the carpal tunnel tunnel. J Hand Surg [Am] 1977; 2:44–53.
20. Phalen GS. The carpal-tunnel syndrome:Seventeen years' experience in diagnosis and treatment of six hundred and fifty-four hands. J Bone Joint Surg 1966; 48A:211–28.
21. Phalen GS. The carpal-tunnel syndrome: Clinical evaluation of 598 hands. Clin Orthop Rel Res 1972; 83:29–40.
22. Arner M, Hagberg L, Rosen B. Sensory disturbances after two-portal endoscopic carpal tunnel release: a preliminary report. J Hand Surg [Am] 1994; 19:548–51.
23. Gelberman RH, Hergenroeder PT, Hargens AR, et al. The carpal tunnel syndrome: a study of canal pressure. J Bone Joint Surg 1981; 63A: 896–903.
24. Szabo RM, Gelberman RH, Williamson RV, et al. Vibratory sensory testing in acute peripheral nerve compression. J Hand Surg [Am] 1984; 9:104–9.
25. Okutsu I, Ninomiya S, Hamanaka I, et al. Measurements of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome. J Bone Joint Surg 1989; 71:679–83.
26. Gartsman GM, Kovach JC, Crouch CC, et al. Carpal arch alteration after carpal tunnel release. J Hand Surg [Am] 1986; 11:372–4.
27. Viegas SF, Pollard A, Kaminski A. Carpal arch alteration and related clinical status after endoscopic carpal tunnel release. J Hand Surg [Am] 1992; 17:1012–16.
28. Kiritsis PG, Kline SC. Biomechanical changes after carpal tunnel release: A cadaveric model for comparing open, endoscopic, and step-cut lengthening techniques. J Hand Surg [Am] 1995; 20:173–80.
29. Menon J. Endoscopic carpal tunnel release: Preliminary report. Arthroscopy 1994; 11:82–90.
30. Brown MG, Keyser B, Rothenberg ES. Endoscopic carpal tunnel release. J Hand Surg [Am] 1992; 17:1009–11.
31. Chow JCY. Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994; 10:637–46.
32. Nagle DJ, Fischer TJ, Harris GD, et al. A multicenter prospective review of 640 endoscopic carpal tunnel releases using the transbursal and extrabursal Chow techniques. Arthroscopy 1996; 12:139–43.
33. Wheatley MJ. A simple technique for identification of the distal extent of the transverse carpal ligament during single-portal endoscopic carpal tunnel release. J Hand Surg [Am] 1996; 21:1109–10.
34. Mirza MA, King ETJ. Newer techniques of carpal tunnel release. Orthop Clin North Am 1996; 27:355–71.
35. Nath RK, Mackinnon SE, Weeks PM. Ulnar nerve transection as a complication of two-portal endoscopic carpal tunnel release. J Hand Surg [Am] 1993; 18:896–8.
36. Del Piñel F, Cruz-Camara A, Jado E. Total ulnar nerve transsection during endoscopic carpal tunnel release. Arthroscopy 1997; 13:235–7.
37. Dheansa BS, Belcher HJCR. Median nerve contusion during endoscopic carpal tunnel release. J Hand Surg [Br] 1998; 23:110–1.
38. Scoggin JF, Whipple TL. A potential complication of endoscopic carpal tunnel release. Arthroscopy 1992; 8: 363–5.
39. Atroshi I, Johnsson R, Ornstein E. Endoscopic carpal tunnel release: prospective assessment of 255 consecutive cases. J Hand Surg [Br] 1997; 22:42–7.
40. Elmaraghy MW, Hurst LN. Single-portal endoscopic carpal tunnel release: Agee carpal tunnel release system. Ann Plast Surg 1996; 36:286–91.
41. Chow JCY. Endoscopic release of the carpal ligament for carpal tunnel syndrome: 33-month clinical result. Arthroscopy 1990; 6:288–96.
42. Nagle DJ. Endoscopic carpal tunnel release. In favor. Clin Plast Surg 1996; 23:477–86.
43. Madonia F, Rigoni G. Analyse rétrospective de 600 cas de tunnel carpieu opérés selon la même technique et par le même opêrateur. Helv Chir Acta 1991; 58:393–4.
44. Erdmann MW. Endoscopic carpal tunnel decompression. J Hand Surg [Br] 1994; 19:5–13.
45. Kuschner SH, Brien WW, Johnson D, Gellman H. Complications associated with carpal tunnel release. Orthop Rev 1991; 20:346–52.
Keywords:

Carpal tunnel syndrome; Open carpal tunnel release; Endoscopic carpal tunnel release; Complications; Operative techniques

© 2001 Lippincott Williams & Wilkins, Inc.