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Diagnostic and Therapeutic Approach to Acute Scaphoid Fractures

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Diagnostic and Therapeutic Approach to Acute Scaphoid Fractures Published online: 2020-11-24 THIEME Update Article | Artículo de Actualización 109 Diagnostic and Therapeutic Approach to Acute Scaphoid Fractures Abordaje diagnóstico y terapéutico de las fracturas agudas de escafoides Fernando Polo Simón1,2,3 Belén García Medrano1,3 Pedro J. Delgado Serrano1,3 1 Hand Surgery and Microsurgery Unit, Hospital Universitario HM Address for correspondence Fernando Polo Simón, MD, Unidad de Montepríncipe, Boadilla del Monte, Madrid, Spain Cirugía de la Mano y Microcirugía, Hospital Universitario HM 2 Mutua Universal, Madrid, Spain Montepríncipe, Boadilla del Monte, Madrid 3 Orthopedic Surgery and Traumatology Service, Hospital (e-mail: [email protected]). Universitario HM Montepríncipe, Boadilla del Monte, Madrid, Spain Rev Iberam Cir Mano 2020;48:109–118. Abstract The scaphoid is the carpal bone that most often fractures, accounting for up to 70% of carpal fractures and 11% of hand fractures. It is the second most common arm fracture, only surpassed by fractures of the distal radius. Despite being so common, these fractures can be difficult to diagnose and treat due to the anatomic and physiological particularities of the bone, including its precarious vascularization, its complex three-dimensional structure, and its ligament connections, which greatly contribute to the risk of complications such as malunion, pseudoarthrosis and avascular necrosis. Although there are many published Keywords studies on the treatment of these injuries, there is still controversy over what is the most ► scaphoid fracture suitable one for certain fracture types. The present article is a comprehensive and updated ► carpus review of the literature. Combining strategies for clinical and radiological diagnosis, we ► wrist propose a complete algorithm for the diagnosis of scaphoid fractures based on the varying ► scaphoid availability of resources, and we also describe the most appropriate therapeutic approach for ► carpal fractures the different types of acute fractures of this bone. Resumen El escafoides es el hueso del carpo que con mayor frecuenciase fractura; comprende hasta el 70% de las fracturas carpianas, y el 11% de las de la mano. Estas fracturas constituyen las segundas en frecuencia de todo el miembro superior, sólo superadas por las fracturas de la extremidad distal delradio. Apesardeser tanfrecuentes,puedenserdifícilesdediagnosticar ydetratardebidoalas particularidades anatómicas y fisiológicas del hueso, incluyendo su precaria vascularización, su compleja estructura tridimensional, y sus conexiones ligamentosas, que contribuyen al riesgo de Palabras clave complicacionescomolauniónenmalaposición,lapseudoartrosis,ylanecrosisavascular.Aunque ► fractura de escafoides existan numerosos estudios publicados sobre el tratamiento de estas lesiones, aún existe ► carpo controversia sobre cuál es el más adecuado para determinados tipos de fractura. En este artículo ► muñeca se hace una revisión completa y actualizada de la literatura. Combinando estrategias de ► escafoides diagnóstico clínico y radiológico, se propone un algoritmo completo para el diagnóstico de las ► fracturas del carpo fracturas de escafoides en función dela distinta disponibilidad de medios, y se expone el abordaje ► fracturas carpianas terapéutico más apropiado para los distintos tipos de fracturas agudas de este hueso. received DOI https://doi.org/ Copyright © 2020 Thieme Revinter April 1, 2020 10.1055/s-0040-1718457. Publicações Ltda, Rio de Janeiro, Brazil accepted ISSN 1698-8396. July 27, 2020 110 Diagnostic and Therapeutic Approach to Acute Scaphoid Fractures Polo Simón et al. Epidemiology the proximal 70% to 80% of the scaphoid depends on branches of this artery that pierce the bone in a narrow, The scaphoid is the most frequently fractured carpal bone, non-articulated dorsal area, called dorsoradial ridge, and and is involved in up to 70% of carpal fractures,1 and 11% of supply it retrogradely. This ridge separates the proximal hand fractures; scaphoid fractures are the second most and dorsal articular surfaces of the distal palmar scaphoid. common upper-limb fracture, only surpassed by distal-radial The vascularization of the remaining 20% to 30% distal fractures.2 According to the recent literature, the incidence of scaphoid is performed by small, direct palmar branches this injury ranged from 22 to 141 cases per 100 thousand from the radial artery or superficial palmar arch that enter people per year.3 However, in a more recent publication the scaphoid tubercle and the collateral circulation from the using the US National Electronic Injury Surveillance System anterior interosseous artery.2,5,8,9 Some authors believe that database, Van Tassel et al4 concluded that the current figure vessels from scaphoid proximal and distal areas communi- was much lower than what had been described in previous cate within the bone,10 but others do not.9 Similarly, some publications, with only 1.47 cases per 100 thousand people authors speak about a potential third source of blood supply, per year. Most of these fractures occur in young subjects, inconsistent and thin, through the scapholunate ligament,11 mostly in the age group between 20 and 29 years.4 In while others vehemently question it.9 This unique vasculari- children, scaphoid fractures are much less common, repre- zation predisposes the scaphoid, especially its proximal pole, senting only 3% of pediatric hand and wrist fractures. There is to fracture-related avascular necrosis and pseudarthrosis. a clear predominance of scaphoid fractures in men (66.4%). The scaphoid connects the proximal and distal rows of the Nonetheless, recent studies observed an increased preva- carpal bones, affecting the mobility of each row according to lence in women, probably due to their greater participation its position and functional demand. This effect results from in organized sports. Although very common, these injuries multiple ligamentous attachments that play a crucial role in may be difficult to diagnose and treat due to the anatomical wrist stability and biomechanics. The present article does and physiological characteristics of the scaphoid. not intend to discuss specific details of the anatomy of the carpal ligament, but its knowledge is recommended for a Anatomy better understanding of wrist biomechanics and scaphoid pathology. In displaced fractures, the proximal pole is ex- The scaphoid has a complex three-dimensional structure, tended due to its attachment to the lunate through the described as an irregular, slightly twisted, S-curved ellipsoid. scapholunate ligament, while the distal fragment remains Its longitudinal axis is oriented at approximately 45° to the flexed due to its intimate union with the trapezius and the longitudinal axis of the hand in both the sagittal and coronal trapezoid through the triscaphe (scaphotrapeziotrapezoid) planes.5 This complex morphology hampers the interpreta- ligament, giving rise to the characteristic hump deformity of tion of the radiographs, the pattern of the fractures, and the the scaphoid. evaluation of the displacement. In conclusion, its poor vascularization, anatomy and liga- The scaphoid consists of four parts: tubercle, waist, mentous attachments greatly contribute to the risk of mal- proximal pole, and distal pole. Most authors, however, union and pseudoarthrosis.2 include the tubercle as part of the distal pole, without any fi speci c distinction. Regarding the proximal pole, there is Injury Mechanism much discrepancy as to its initial point. The most accepted definition refers to the proximal 20% of the bone.6 Most Most scaphoid fractures occur after a fall with the extended fractures (approximately 70%) occur at the scaphoid waist, wrist and radial deviation.12 The exact biomechanical mech- with 20% at the distal pole, 5% at the tubercle, and the anism has been discussed for decades. Todd,13 the first to remaining 5% at the proximal pole. Certain properties of study it, stated that it resulted from excessive stress, while the bone structure may contribute to the higher incidence of Cobey and White14 argued that fractures are produced by waist fractures. In a cadaveric computed tomography (CT) excessive compression on the concave medial joint surface of study, Bindra7 found out that the scaphoid is denser at the the scaphoid by the capitate bone. In a cadaveric study, proximal pole, in which the trabeculae are thicker and more Frykman15 demonstrated that fractures are more likely to firmly organized; the trabeculae are thinner, scarcer and occur with wrist hyperextension and radial deviation, a dispersed at the scaphoid waist.2 Many publications have finding later confirmed by Weber and Chao,16 who were estimated that 70% to 80% of the total scaphoid covering able to recreate scaphoid fractures by load application on the surface is cartilaginous. This characteristic covering limits radial area of the palm with the wrist in 95° to 100° of the entry area for blood vessels, resulting in a precarious extension.17 Other fracture mechanisms described include vascularization. Furthermore, the small vessels that nourish direct blows or axial compression of the hand with the wrist the scaphoid are difficult to appreciate within the capsular in a neutral position. structures, and there is a risk of unintentional injury during surgical interventions. As such, knowledge on the vascular Diagnosis anatomy of the scaphoid is critical. The dorsal scaphoid artery, a branch of the radial artery, is the most important Despite the high frequency of scaphoid fractures, their vessel
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