Morphological Classification of Arch of Frohse and Its Implication in Compression of Deep Branch of Radial Nerve

BACKGROUND Arcade of Frohse (AF) is a tendinous superior margin of superficial layer of supinator muscle which was first described by Frohse and Frankel in 1908. Since then it has been studied by many authors and held accountable as one of the essential components for compression of deep branch of radial nerve (DBRN) which leads to radial tunnel syndrome. Considering AF as an important element of compression, we made an attempt to classify it on the basis of its shape and to find out if any particular shape has a predominant role in compression of the nerve. We also observed the structure of superior and inferior margin of the supinator muscle. METHODS This study was conducted among 80 (70 males and 10 females) formalin fixed upper limbs present in the Department of Anatomy. The limbs were maintained in supine with slightly flexed position and dissection was performed to expose the supinator muscle. The proximal and distal borders of supinator muscles were examined meticulously with the help of magnified lens. The morphometric measurements were taken with the help of a digital caliper. RESULTS The FA is classified into four categories as loop, high arc, low arch and linear shaped. The most frequent shape observed was arch shaped (high and low arch) about 66%, followed by loop shaped (30%) and least was linear shaped (2.5%). On the basis of structure, the proximal and distal margin of supinator muscle was reported to be tendinous in majority of the cases. The distance of the AF from the fixed reproducible anatomical landmark like inter epicondylar line (IEL) was measured and the average distance found was 3.36 cm. CONCLUSIONS Knowledge of different shapes would aid surgeons and radiologists for better approach towards diagnosis and management of supinator syndrome. The morphometric finding can be useful for surgeons to locate the superior margin of supinator (AF) in surgical procedures for decompression of DBRN in supinator syndrome. KEY WORDS Arcade of Frohse, Inter Epicondylar Line, Supinator Muscle, Deep Branch of Radial Nerve and Radial Tunnel Syndrome

Left-Hand Injuries in Guitarists

Guitarists are susceptible to multiple injuries directly related to faulty left-hand technique: carpal tunnel syndrome, lateral epicondylitis, median epicondylitis, neuropathy of the ulnar nerve, supinator syndrome, osteoarthritis and capsulitis of the first carpometacarpal and digital neuritis. A literature review shows that the causes of these injuries are all related to excessive flexion or extension of the wrist, exaggerated bending of the elbow, prolonged periods of maximal supination of the wrist and large amounts of tensioned positions. The article analyzes guitar left-hand technique and proposes technical and postural approaches that address these causes and theoretically decrease the risk of playing-related injuries.

Intra-Tester Reliability and Concurrent Validity of Musculoskeletal Ultrasound and Vernier Calipre in Quantifying the Anteroposterior Diameter of the Common Extensor Origin of the Forearm and the Radial Nerve: A Cadaveric Study

Introduction: The literature reports an increase in anteroposterior diameter of the common extensor origin (CEO) of the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC) or the radial nerve in painful elbows diagnosed with lateral epicondylalgia (LE) or supinator syndrome. The edge-to-edge measurements of these anatomical structures are quantified using musculoskeletal ultrasound (MSUS). However, in the current literature, reports on the reliability and validity of MSUS measurements of the CEO (of ECRB and EDC) and the radial nerve are not found. In this study, reliability was measured for three testers in determining the anteroposterior diameter of the CEO (of ECRB and EDC) and the radial nerve. Moreover, the concurrent validity was determined of MSUS measurements with Vernier calipre measurements using formalin preserved elbows of human cadavers. Methodology: Cadaver measurements of the CEO (of ECRB and EDC) and the radial nerve were performed. Initially, the sonologist measured the anteroposterior diameter of the CEO (of ECRB and EDC) and the radial nerve. A month after scan, the formalin preserved cadavers were dissected. Consequently, the anteroposterior diameter of the exposed CEO (of ECRB and EDC) and the radial nerve was measured using the Vernier calipre. Results: Eight upper extremities of four embalmed Filipino cadavers (2 males: 2 females) were dissected. A total of seven (7) CEO of EDC, seven (7) CEO of ECRB, and eight (8) radial nerves at the level of the radial head in the elbows of four (4) cadavers were measured using the MSUS and the Vernier calipre. The MSUS and Vernier calipre protocol used in this study was found to be reliable, p > 0.05. However, in all three levels of interest, the MSUS measurements were statistically different from the Vernier calipre measurements, p < 0.05. Conclusion: MSUS and Vernier calipre measurements are reliable methods in measuring the CEO (of ECRB and EDC) and the radial nerve. While each of these methods is reliable in measuring the anteroposterior dimensions of the CEO (of the EDC and ECRB) and the radial nerve, substituting one for the other yielded statistically different measurement results.