PMC9880394_01
PMC9880394_02
Ultrasound evaluation of the carpal tunnel during finger extension (A) and flexion (B), with the blue line on the palm indicating the superficial palmar arch of the ulnar artery. The carpal tunnel knife for minimally invasive carpal tunnel release (C). The blunt-tipped needle for confirmation of the completeness of decompression (D). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
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fig1
Dynamic motion of the median nerve was examined by asking the patient to flex (Fig. 1A) and extend (Fig. 1B) the fingers. The upward migration of the median nerve was limited by the flexor retinaculum (Fig. 2A and B and Video 1). The carpal tunnel knife (Fig. 1C) was then inserted with one tip above and the other tip below the flexor retinaculum. Subsequently, the blunt-tipped needle (Fig. 1D) was introduced again into the carpal tunnel.
Ultrasound imaging and schematic drawing of the carpal tunnel outlet before the surgery in the neutral resting position (A) and finger extension (B). The median nerve (asterisks) appeared flattened and compressed between the flexor retinaculum (FR) and flexor tendons (T) when the fingers were extended.. TPE, trapezium; HAM, hamate.
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The upward migration of the median nerve was limited by the flexor retinaculum (Fig. 2A and B and Video 1). Complete decompression was defined by the visualization of a full-thickness gap over the flexor retinaculum with the median nerve migrating more superficially than the imaginary line linking the trapezium and hamate (Fig. 3A and B and Video 2).
Ultrasound imaging and schematic drawing of the carpal tunnel outlet after surgery in the neutral resting position (A) and finger flexion (B). The median nerve (asterisks) appeared to be pushed upward by the finger flexor tendons (T) and bulged through the gap (black arrows) on the flexor retinaculum (FR) when the fingers were flexed. TPE, trapezium; HAM, hamate. Stars, synovial tissue.
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Complete decompression was defined by the visualization of a full-thickness gap over the flexor retinaculum with the median nerve migrating more superficially than the imaginary line linking the trapezium and hamate (Fig. 3A and B and Video 2). Decompression was considered complete if the needle could be seen moving from the carpal tunnel to the subcutaneous layer through the gap on the flexor retinaculum (Fig. 4A and B and Video 3).
The blunt-tipped needle (black arrowheads) was inserted into the opened carpal tunnel outlet (A) and gradually moved upward (B) to confirm the completeness of surgical release. TPE, trapezium; HAM, hamate; FR, flexor retinaculum; T, flexor tendons; stars, synovial tissue; asterisks, median nerve.
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Decompression was considered complete if the needle could be seen moving from the carpal tunnel to the subcutaneous layer through the gap on the flexor retinaculum (Fig. 4A and B and Video 3).