Comparison of Carpal Tunnel Release Methods and Complications

One patient had respiratory insufficiency secondary to chemical pneumonitis. The patient was sedated during an endoscopic carpal tunnel release, aspirated, and kept intubated in the intensive care unit until the morning after surgery.

An early complex regional pain syndrome diagnosis was made in a patient with underlying neuropathy and a preoperative “profound” median neuropathies diagnosis at the wrist with underlying peripheral neuropathy found on nerve conduction studies. The patient experienced an unusual amount of postoperative pain and edema after an uncomplicated open carpal tunnel release. This was treated with rapid intervention using anti- inflammatories and hand therapy. The patient also started a regimen of skin care, edema management, neuroreeducation, and contrast baths. Symptoms responded within a week.

There were 12 wound complications: 10 in open and 2 in endoscopic surgeries. Total wound complications were equally split between patients with and without diabetes. Infection and dehiscence were noted. Sutures were removed an average of 9.6 days after surgery in the patients whose wounds broke down. A statistically significant relationship was found only between the open method of release and wound dehiscence (P < .05).

There was no statistically significant difference in the overall complication rate in the NFSGVHS population when comparing endoscopic with open carpal tunnel release or when comparing the risk of postoperative tendonitis, wound infection, or return to the OR.

Discussion

Carpal tunnel syndrome was documented by James Paget in mid-19th century in reference to a distal radius fracture.² It is the most common peripheral nerve compression, with an incidence ranging from 1 to 3 cases per 1,000 subjects per year and a prevalence of 50 cases per 1,000 subjects per year.³ In an active-duty U.S. military population, the incidence of carpal tunnel syndrome is 3.98 per 1,000 person years.⁴

Related: Risk Factors for Postoperative Complications in Trigger Finger Release

The endoscopic method of release was first introduced in 1989 by Okutsu and colleagues.⁵ About 500,000 carpal tunnel releases are now performed in the U.S. every year, with 50,000 performed endoscopically.³ There were 185 carpal tunnel releases (56 endoscopic and 129 open) performed at the NFSGVHS in 2012.⁶ The minimally invasive procedure was designed to preserve the overlying skin and fascia, promoting an earlier return to work and daily activities. This is particularly relevant for manual workers who desire rapid return of grip strength. Multiple published reports have found more rapid recovery based on a reduction in scar tenderness, increase in grip strength, or return to work.^7-13 Patients seem to have equivalent results over the long term, ranging from 3 months to 1 year.^7,8,13-15 Return to work was not evaluated in this study, because many patients were either retired or not working steadily.

The endoscopic method was criticized after its introduction due to its potential increase in major structural injury to the median nerve, ulnar nerve, palmar arch, ulnar artery, or flexor tendons.¹⁶ A meta-analysis found improved outcomes but a statistically significant higher complication rate in endoscopic, compared with open release (2.2% in endoscopic vs 1.2% in open).¹⁶ Referral patterns have found iatrogenic nerve injury in patients referred by surgeons without formal hand fellowship training.¹⁷ There is a wide variety of background training for surgeons who may offer carpal tunnel release, including plastic surgery, orthopedics, general surgery, and neurosurgery.

Related: Arthritis, Infectious Tenosynovitis, and Tendon Rupture in a Patient With Rheumatoid Arthritis and Psoriasis

Major structural injuries were reported by hand surgeons using both open and endoscopic methods in a questionnaire sent to members of the American Society for Surgery of the Hand, indicating that either approach demands respect.¹⁸ A large review of the literature from 1966 to 2001 by Benson and colleagues found that the endoscopic approach was not more likely to produce injury to tendons, arteries, or nerves compared with the open approach and actually had a lower rate of structural damage (0.49% vs 0.19%).¹⁹ Researchers who conducted this study confirmed one common digital nerve injury in an endoscopic converted to open technique, using a distally-based port with the blade not being deployed via the endoscopic method. The endoscopic method has been found to have a higher rate of reversible nerve injury (neuropraxia) compared with the open technique.^7,10,19

The NFSGVHS results found a higher rate of wound dehiscence. More frequent wound site complications, particularly infection, hypertrophic scar, and scar tenderness have been noted using the open method.^3,8,20 This is probably due to the deeper and slightly larger incision used for the open method compared with the smaller and shallower incisions used for the endoscopic release.

There is the inevitable learning curve for the endoscopic release due to the more complicated nature of the procedure. The NFSGVHS conversion rate was 23.7% over the 5-year period from 2005 to 2010. All 3 fellowship- trained hand surgeons were in their first year of practice at the time of the study, so the authors anticipate a lower conversion rate in forthcoming studies. The NFSGVHS researchers did not consider converting to an open technique to be a complication and believe it is appropriate to teach plastic surgery residents and fellows to have a low threshold to convert when visualization is not optimal and the potential for significant injury exists. The learning curve and a higher conversion rate have been acknowledged by Beck and colleagues with no increase in morbidity.²¹