Carpal tunnel syndrome (CTS) results from the compression of the median nerve as it passes through the carpal tunnel in the wrist. This compression typically leads to symptoms like pain, numbness, and tingling in the hand and fingers. When non-surgical treatments fail, carpal tunnel release surgery is performed to alleviate the pressure. The surgery involves cutting a specific band of tissue to increase the space within the tunnel. The ligament cut during carpal tunnel release surgery is the Transverse Carpal Ligament (TCL).
The Transverse Carpal Ligament
The Transverse Carpal Ligament (TCL) is a band of tissue that spans across the wrist, forming the roof or palm-side boundary of the carpal tunnel. The tunnel’s bottom and sides are made up of the carpal bones of the wrist. The TCL connects to bones on both sides of the wrist, creating a confined space.
Within this narrow passage, nine flexor tendons, which control finger movement, pass alongside the median nerve. The ligament stabilizes the carpal bones and acts as a pulley for the flexor tendons to enhance grip strength. The rigid nature of the TCL becomes problematic in carpal tunnel syndrome because swelling or inflammation inside the tunnel compresses the median nerve underneath the ligament.
Relieving Pressure on the Median Nerve
Carpal tunnel release is an effective treatment because it directly targets the source of the mechanical compression. Surgeons cut the Transverse Carpal Ligament, dividing it completely or partially, which immediately disrupts the confined structure of the carpal tunnel. This action releases the restrictive force on the structures inside.
Cutting the ligament increases the space within the carpal tunnel, allowing the median nerve and flexor tendons to move freely. This decompression leads to an immediate drop in pressure on the median nerve. Relieving this chronic compression allows the nerve to begin healing, resulting in the eventual reduction or elimination of symptoms like numbness and pain. The procedure can be performed using an open technique, involving an incision in the palm, or an endoscopic approach, which uses a smaller incision and a camera.
Structural Changes Following Surgery
Patients often wonder what happens to the cut ligament, given its function in the wrist’s structure. Following the division of the TCL, the ligament does not grow back together in its original state. Instead, the gap created by the surgical cut is gradually filled in with scar tissue, which is a natural part of the body’s healing process.
This new fibrous tissue bridges the gap between the two ends of the divided ligament. This scar tissue is longer and more pliant than the original TCL, creating a permanently widened carpal tunnel. This process takes place over several months, often reaching its final form between six and twelve months after the procedure. This structural adaptation ensures that the median nerve remains decompressed over the long term, offering a definitive solution for carpal tunnel syndrome.