meta-analysis supports the conclusion that endoscopic carpal tunnel release is favored over the open carpal tunnel release in terms of a reduction in scar tenderness and increase in grip and pinch strength at a 12-week follow-up The use of an endoscope to release the carpal tunnel was first described in 1989 by Okutsu et al. Here a flexible clear plastic tube was used with a standard endoscope to identify the transverse carpal ligament and release it with a retrograde knife. Variations Many variations of the endoscopic or arthroscopic methods have been described, each with its own unique apparatus and surgical protocol. The two more common and popular devices were referred to early on as the Chow device and the 3M Agee device. The Chow device is a two-portal device, while the 3M Agee endoscopic carpal tunnel release system is a single-portal device. The Chow device was produced by Dyonics and early papers documented its success. It was heralded by its corporate manufacturer as a breakthrough in carpal tunnel surgery. The Agee 3M device used a single, transverse incision in the area of the proximal wrist flexion crease. The Chow two-portal or two-incision device has had other manifestations, and the Agee device was bought by MicroAire Surgical Instruments. Both methods are still in use today. Additional modifications in technique for a smaller or limited incision have been accompanied by many variations of knives, rasps and tubes through which these instruments and the imaging arthroscope or endoscope are passed. Despite the many manifestations of these devices they are all either a single or two portal system. Athrex, Brown-Instratek, Linvatek and other manufacturers modified the original one or two portal systems for endoscopic carpal tunnel release. Most of these methods utilize an endoscope to visualize the under surface of the transverse carpal ligament while others simply rely on instrumentation that allows for a smaller incision and instrumentation that aids in guiding the surgeon's modified blade or knife. Lastly, several years later a distal portal or single incision in the distal palm was advocated by a group from Louisville. Effectiveness Many studies have been done to determine whether the perceived benefits of a limited endoscopic or arthroscopic release are truly significant. One prospective, randomized, multi-center study found no significant differences between the two groups with regard to the secondary quantitative outcome measurements. However, the open technique resulted in more tenderness of the scar than