Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy and affects 3-6% of adults in the United States at a total annual cost of over 2 billion dollars. In patients with severe or refractory symptoms, carpal tunnel release (CTR) represents the definitive management option, and over 500,000 CTRs are performed annually in the United States with over 90% of patients reporting clinical improvement. Although initially performed via a large palmar incision (3-5 cm), CTR techniques have continually evolved to reduce surgical trauma with the goal of improving cosmesis, reducing post-operative pain, and promoting faster recovery. Currently available CTR techniques include mini-open CTR via a single, 1-3 cm palmar incision (mOCTR), endoscopic CTR via one (wrist) or two (wrist and palm) 1-2 cm incisions (ECTR), and ultrasound guided CTR via a single < 1 cm wrist or palmar incision (USCTR).

According to Defense Medical Epidemiology Database information, in 2016, there were 16,823 active duty service members, across the Army, Navy, Air Force and Marines diagnosed with carpal tunnel syndrome. This amounts to approximately 13/1000 service members a year. The ability to have adequate numbers of orthopedic providers to conduct the necessary carpal tunnel release surgeries to meet this demand can be limited for various reasons such as a remote location or general lack of specialty care at the MHS site. As described above, point-of-care musculoskeletal providers now have the capability to conduct these procedures outside of the operating room environment. Further, early evidence of USCTR vs. traditional mOCTR indicates a more rapid recovery and likely quicker return to duty.

Regardless of technique, the primary goal of CTR is to transect the transverse carpal ligament (TCL) while avoiding injury to nearby neurovascular structures. Although ECTR may promote a faster recovery compared to mOCTR, concerns have been raised regarding the potential for increased complications due to limited visualization of surrounding structures during TCL transection. USCTR techniques combine a single small incision with direct visualization of at-risk structures such as the median nerve and its thenar motor ranch/recurrent motor branch, ulnar vessels, and superficial palmar arterial arch. To date, over 630 cases of USCTR have been reported in the peer-reviewed literature with a >98% success rate and no documented neurovascular injuries. Furthermore, a recently published, single surgeon, prospective randomized clinical trial comparing mOCTR to USCTR reported that patients treated with USCTR experienced significantly faster recovery with respect to functional scores, pain reduction, and pain medication discontinuation.

Carpal tunnel syndrome (CTS) is the most common peripheral neuropathy and occurs in 3-6% of adults in the United States. While many patients with CTS respond to conservative treatment, there is strong evidence that supports operative management. Post-op complications, while rare, are frequently due to nerve injury and include post-operative pain, dysesthesia, paresthesia, and formation of painful neuromas. Variations in the anatomy of the median nerve increases the risk of damage to branches. Various anatomical variants in the carpal tunnel have been suggested to contribute to median nerve compression, including bifurcation of the median nerve, persistent medial artery, extra tendons within the carpal tunnel, and palmaris longus variations.

The purpose of the study is to utilize ultrasound to investigate the prevalence of variations in the anatomy of the median nerve and surrounding structures, to compare the rate of variation in individuals with carpal tunnel syndrome symptoms verses those without, and to evaluate if specific anatomic variations are more prevalent in different patient populations.