Carpal tunnel pressure is a key factor in the etiology of carpal tunnel syndrome. Numerous approaches have been conducted to measure carpal tunnel pressure. However, most techniques are invasive and take time and effort. We have developed an innovative approach to noninvasively assess the tunnel pressure by using the ultrasound surface wave elastography (USWE) technique. In a previous study it was shown that the shear wave speed in a tendon increased linearly with increasing tunnel pressure enclosed the tendon in a simple tendon model. This study aimed to examine the relationship between the carpal tunnel pressure and the shear wave speeds inside and outside the carpal tunnel in a human cadaveric model. The result showed that the shear wave speed inside the carpal tunnel increased linearly with created carpal tunnel pressure, while the shear wave speed outside the carpal tunnel remained constant. These findings suggest that noninvasive measurement of carpal tunnel pressure is possible by measuring the shear wave speed in the tendon. After fully establishing this technology and being applicable in clinic, it would be useful in the diagnosis of carpal tunnel syndrome. For that reason, further validation with this technique in both healthy controls and patients with carpal tunnel syndrome is required. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:477-483, 2018.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy occurring in upper limbs. The etiology, however, has not been fully understood yet. Median nerve could be compressed by either increase of carpal tunnel pressure (CTP) or direct impingement when it is forced toward to carpal ligament especially in wrist flexion leading to CTS development. Thus, the increase of carpal tunnel pressure is considered an important role in CTS development. It has been identified that forces applied to the palm would affect the CTP. However, the quantitative relationship between palmar contact force and CTP is not known. The purpose of this study was to quantitatively evaluate the relationship between palmar contact force and CTP. Eight human cadaveric hands were used. The CTP was measured with a diagnostic catheter-based pressure transducer inserted into the carpal tunnel. A custom made device was used to apply forces to the palm for the desired CTP. Palmar contact forces corresponding to the determined CTP level were recorded respectively. The testing was repeated with different ranges of tension applied to the flexor digitorum superficialis tendon of the third finger. The tensions were constant at 50 g for the other flexor tendons and median nerve. The results showed that CTP increased linearly with the force applied to the palm. When CTP was 30 mmHg, mean values of the contact force to the palm was 293 g (SD: 15.2) including all tensions. These results would help to understand the effect of daily activities with hands on CTP.

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Background Scaphoid nonunion with humpback deformity and avascular necrosis (AVN) is a challenging problem. Correction of dorsal intercalated segment instability (DISI) requires grafting of a large and hard vascularized bone segment onto the volar side of the scaphoid. Purposes We have been treating the patients with one-incision vascularized bone grafting technique for scaphoid nonunion to improve blood supply and correct humpback deformity. We evaluated these cases retrospectively to the surgical efficacy of our procedure. Methods We harvested vascularized bone from the dorsal side of the radius using the method by Zaidemberg et al and inserted the cortical aspect into the scaphoid volar side using a direct lateral approach. Totally, 11 patients (nine males andtwo females) with a mean age of 40 years were recruited for this study. The mean time from fracture to treatment was 6 years and 3 months. The mean preoperative radiolunate angle was 25 degrees. All the patients showed AVN of the proximal scaphoid on T1-weighted images. An averaged follow-up period was 2 years and 3 months. Results Postoperative computed tomography revealed bony union in 10 patients (91% of union rate) with a mean modified Mayo'swrist score of 88 points (range, 75–100 points) and a mean disabilities of arm, shoulder, and hand (DASH) score of 4 points (range, 0–20 points). The mean radiolunate angle was corrected from 25 to 5 degrees. No adverse events were observed, except temporary mild paresthesia of the radial nerve territory in two patients. Conclusion This technique effectively corrected DISI in patients with scaphoid nonunion accompanied by humpback deformity and AVN.

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