Response to the Letter to the Editor on “Ultrasound Anatomy of the Transverse Carpal Ligament”
We appreciate the clarification that the structure traditionally called the transverse carpal ligament (TCL) in actuality is made up of a superficial volar layer, the sagittally oriented superficial palmar aponeurosis (SupPA) and the deeper transverse-oriented TCL. Because these two layers are tightly adherent and impossible to be distinguished visually, they have been traditionally called the TCL, and both are routinely cut during open carpal tunnel release surgery. Stecco et al.1 clarified that the SupPA and TCL are distinct structures based on findings of careful dissection, histological and immunohistochemical staining, and magnetic resonance imaging. This has become a clinically relevant point now that high-resolution ultrasound is increasingly used to image the carpal tunnel and to guide interventions. Guo et al.2 have recently described a revision to their originally described ultrasound-guided percutaneous looped thread carpal tunnel release technique by which the SupPA is spared and only the TCL is cut. How this will affect clinical outcomes is uncertain. Inasmuch as the SupPA is richly innervated, sparing it may result in less post–carpal tunnel release pillar pain. Alternatively, preserving it may provide a scaffold that enables the two cut ends of the TCL to reattach, increasing the chance of carpal tunnel syndrome recurrence. Future research comparing the results of open carpal tunnel release, looped thread carpal tunnel release that includes the SupPA, and looped thread carpal tunnel release that spares the SupPA is recommended and will be required to answer this relevant question.