Introduction: Currently, carpal tunnel release (CTR) for the management of carpal tunnel syndrome is based on the premise that pressure on the median nerve can be surgically reduced. Three volar fibrous layers have been described at the hand and forearm. Histologic and clinical studies suggest a mechanical function for the deepest layer. Release of its distal and central portions results in complete decompression. In addition, evidence suggests a denser innervation at the palm, favoring forearm approaches. The rationale for alternative CTR options is to decrease morbidity (weakness, pain, and diminished function) from damage to nonetiologic structures. The size of the incision for CTR has been described as classic (>4 cm), limited (2 to 4 cm), mini (1 to 2 cm), or percutaneous (4 to 6 mm). We hypothesized that a 1-mm forearm incision (ultra–minimally invasive) may further improve clinical results. We developed an anatomic study, a clinical pilot study, and a clinical essay.

Technique: The goal of this video is to demonstrate how to perform ultra–minimally invasive CTR to manage primary carpal tunnel syndrome in patients and cadaver models. We also describe the efficacy, safety, and clinical results of the technique compared with the mini-open technique. Postoperatively, the wound is covered with a nonadherent dressing for 2 days. The procedure is performed without ischemia and under local anesthesia in day surgery and allows for immediate postoperative function.

Discussion/Conclusion: Endoscopic CTR is associated with less morbidity than classic CTR; however, concerns exist with regard to complications. The morbidity of mini-open CTR closely matches that of endoscopic CTR, however, mini-open CTR is performed blindly. Mini-open and percutaneous CTR have been performed under ultrasonographic guidance, with considerable differences favoring the least invasive approach. To our knowledge, ultra–minimally invasive CTR is the least invasive surgical approach. Anatomically, ultra–minimally invasive CTR is effective. The technique safely preserves superficial anatomy and successfully diminishes damage to nonetiologic tissues. Our pilot study showed that a randomized trial was feasible, and no evidence existed to contraindicate or withhold the clinical use of the technique. Our clinical trial showed that ultra–minimally invasive CTR is associated with the same neurologic recovery as mini-open CTR. The former leads to less postoperative morbidity and earlier functional return. Patients who underwent ultra–minimally invasive CTR required a mean of 2.2 days for the discontinuation of analgesic agents, a mean of 4.9 days for return to all daily activities, and a mean of 6 weeks to achieve 78% grip strength. The learning curve for ultra–minimally invasive CTR is steep, and surgeons should learn how to perform easier procedures (eg, injections, trigger digit release) under ultrasonographic guidance before attempting ultra–minimally invasive CTR.