Multicentric carpotarsal osteolysis (MCTO) is a rare skeletal disorder characterized by progressive carpal and tarsal destruction. The upper and lower limbs may be involved, leading to deformities and joint limitation. These anatomic features may be associated with progressive renal failure. The radiographs obtained during childhood showed a carpal and tarsal osteolysis and an asymmetrical involvement. Here, we report on the long-term clinical and radiological findings of three patients with skeletal manifestations of MCTO.

IntroductionAnatomic variations of the median nerve (MN) increase the risk of iatrogenic injury during carpal tunnel release surgery. We investigated whether high-frequency ultrasonography could identify anatomic variations of the MN and its thenar motor branch (MBMN) in the carpal tunnel.MethodsFor each volar wrist of healthy non-embalmed cadavers, the type of MN variant (Lanz classification), course and orientation of the MBMN, and presence of hypertrophic muscles were scored by 18-MHz ultrasound and then by dissection.ResultMBMN was identified by ultrasound in all 30 wrists (15 subjects). By dissection, type 1, 2 and 3 variants were found in 84%, 3%, and 13% of wrists, respectively. Ultrasound had good agreement with dissection in identifying the variant type (kappa =0.9). With both techniques, extra-, sub-, and transligamentous courses were recorded in 65%, 31%, and 4% of cases, respectively. With both techniques, the bifid nerve, hypertrophic muscles, and bilateral symmetry for variant type were identified in 13.3%, 13.3%, and 86.7% of wrists, respectively. Agreement between ultrasound and dissection was excellent for the MBMN course and orientation (kappa =1).ConclusionUltrasound can be used reliably to identify anatomic variations of the MN and MBMN. It could be a useful tool before carpal tunnel release surgery.Key Points• Ultrasound can identify variations of the motor branch of the median nerve. • Ultrasound mapping should be used prior to carpal tunnel release surgery. • All sub-, extra-, and transligamentous courses were accurately identified. • Type 3 variants (bifid nerve), hypertrophic muscles, and bilateral symmetry were accurately identified.

IV, retrospective study.

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