Anatomical Safety of the Open Approach in Carpal Tunnel Release: Critical Review of the Evidence and Analysis of the Role of the Tanzer Incision

Introduction. Surgical carpal tunnel release constitutes the definitive treatment for patients with moderate to severe carpal tunnel syndrome (CTS). Although endoscopic techniques have gained popularity, open surgery continues to be widely performed, with comparable long-term functional outcomes. In this context, optimization of the skin incision and reduction of the risk of injury to the recurrent motor branch of the median nerve are of particular importance. The distal anatomical variability described by the Lanz classification provides a fundamental framework for safe surgical planning. Objective. To critically analyze the available anatomical and clinical evidence regarding open carpal tunnel release, integrating the Lanz classification as the anatomical foundation, and to evaluate the role of the Tanzer incision as a potentially neurologically oriented safety approach. An illustrative clinical case is also presented. Materials and Methods. A literature search was conducted in PubMed, Scopus, and the Cochrane Library between 1998 and 2024 using the terms “carpal tunnel release,” “Tanzer incision,” “median nerve variations,” “Lanz classification,” “recurrent motor branch,” and “safe zone.” Anatomical studies, clinical trials, meta-analyses, and systematic reviews published in English and Spanish were included. Particular emphasis was placed on distal median nerve variability patterns and their surgical implications. The review was complemented by the description of a clinical case treated using the Tanzer incision. Results. The available comparative evidence does not demonstrate sustained long-term functional superiority of the endoscopic technique over the open approach, although it may be associated with faster recovery in the early postoperative period. The Lanz classification shows that most potentially vulnerable anatomical variants are located in the radial sector of the carpal tunnel, particularly transligamentous patterns and high divisions of the median nerve. Ulnar displacement of the approach, as proposed by the Tanzer incision, is based on the concept of an “anatomical lower-risk zone,” distancing the ligament division plane from the region where critical variants are concentrated. Conclusions. Safety in open carpal tunnel release largely depends on detailed knowledge of distal median nerve anatomical variability. The Lanz classification provides a useful conceptual framework for surgical planning. In the absence of demonstrated long-term clinical superiority of the endoscopic technique, anatomical optimization of the open approach is essential. The Tanzer incision may be considered an anatomically reasoned alternative aimed at neurological preservation; however, specific comparative studies are required to establish definitive recommendations.