The Journal of hand surgery
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Median nerve displacement and strain in the carpal tunnel region were measured as functions of wrist position and carpal tunnel pressure in 5 cadaver forearms during simulated active finger flexion. The positions of spherical stainless-steel markers embedded within the median nerve and flexor digitorum superficialis of the long finger were measured in 3 dimensions by a radiographic direct linear transformation technique. Each limb was tested in 3 wrist positions (60 degrees extension, neutral, and 60 degrees flexion) and 4 carpal tunnel pressures (0, 30, 60, and 90 mmHg). ⋯ Patterns of strain in the median nerve proximal to the flexor retinaculum were different from those of strain within the carpal tunnel. Nerve strains were affected by wrist position, but carpal tunnel pressure had no effect. The hydrostatic pressure effect associated with carpal tunnel syndrome does not appear to influence median nerve kinetics or kinematics for the wrist positions studied.
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Three cases of large volar plate avulsion fracture at the base of the middle phalanx with significant displacement are reported. In each case, the fracture fragment involved about 30% of the articular surface and was rotated 90 degrees. ⋯ All patients underwent open reduction and internal fixation. The fracture healed in anatomic alignment without articular incongruity or instability in all cases.
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A reflex are from the medial elbow ligaments to the forearm pronator muscles was shown to exist in the feline model. A single articular branch emerging from the median nerve and converging on the medial collateral ligament was identified and stimulated with supramaximal pulses of 100 microseconds duration at a rate of 10 pulses/s. Stimulation of the articular nerve elicited myoelectric activity in the flexor digitorum superficialis, flexor digitorum profundus, flexor carpi radialis, flexor carpi ulnaris, and pronator teres. ⋯ The mean time delay from the application of the stimulus to the corresponding myoelectric discharge ranged from 3.2 to 5.8 ms for the 5 muscles. The existence of a fast-acting reflex arc from the medial elbow ligaments to the forearm muscles both confirms the concept of ligamentomuscular protective synergy (shown to exist in the knee, shoulder, and ankle joints) and extends it to the elbow. This reflex arc has significant implications for both the planning of elbow surgery while preserving the neural supply of the ligaments and for the planning of postsurgical or conservative therapeutic rehabilitation modalities.
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Knowledge of radial nerve motor branch anatomy is important when performing surgery in its vicinity, neurorrhaphy, and nerve blocks and for understanding the rate and order of recovery of muscle function after injury. Twenty normal fresh cadaver arms were dissected to quantitate radial nerve motor branch anatomy in the forearm. Though variable in individual specimens, innervation order from proximal to distal (based on mean shortest branch lengths) was brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor policis longus, extensor policis longus, extensor policis brevis, and extensor indicis proprius. ⋯ Mean distances from a point 100 mm proximal to the lateral epicondyle to the muscle measured along the shortest nerve branch ranged from 97.2 mm for the brachioradialis to 299.8 mm for the EIP. The mean number of muscular branches ranged from 1.1 in the EIP to 4.6 in the EDC. Mean nerve length from the radial styloid to the last motor branch was 115.8 mm.