fractures and dislocations of the carpus by gatobu 6a

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Fractures and dislocations of the carpus By Gatobu 6A

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Fractures and dislocations of the carpus By Gatobu 6A Slide 2 Scope Introduction Anatomy Imaging of carpal bones Lunate fractures/lunate dislocation Perilunate dislocation Slide 3 Introduction Carpus is a complex unit of bony articulations that transfers the forces of the hand to the supporting forearm and upper extremity Allows wide range of motion in 2 planes Carpal bones are 8 in number arranged in 2 rows Main motions Extension Flexion Radial and ulnar deviation The primary axis of motion resides within the head of carpitate. Slide 4 General, surgical and applied anatomy Bones and joints Composed of 8 bones in 2 rows The 8 bones are influenced by Shape of distal radius The distal ulnar Triangular fibrocartilage complex Slide 5 Anatomy of the Wrist Carpal bones tightly linked by capsular and interosseous ligaments. Capsular (extrinsic) ligaments originate from the radius and insert onto the carpus. Interosseous (intrinsic) ligaments traverse the carpal bones. The lunate is the key to carpal stability. Slide 6 Extrinsic ligaments Extrinsic ligaments link the carpal bones to the radius, ulna, and metacarpals. Slide 7 Intrinsic ligaments The intra-articular intrinsic ligaments connect adjacent carpal bones. Slide 8 Lunate Connected to both scaphoid and triquetrum by strong interosseous ligaments. Injury to the scapholunate or lunotriquetral ligaments leads to asynchronous motion of the lunate and leads to dissociative carpal instability. Slide 9 Intercarpal Ligaments Injury to these ligaments leads to abnormal motion between the two rows, and non-dissociative wrist instability patterns. Slide 10 Neurovascular anatomy Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch Slide 11 Neurovascular anatomy The scaphoid, capitate, and about 20% of all lunates are supplied by a single vessel and thus are at risk for avascular necrosis. The trapezium, triquetrum, pisiform, and 80% of lunates receive nutrient arteries through two nonarticular surfaces and have consistent intraosseous anastomoses. AVN is therefore rare. The trapezoid and hamate lack an intraosseous anastomosis and, after fracture, can have avascular fragments. Slide 12 Mechanism of injury Most common is an axial compression force applied with the wrist in hyperextension Most common injury is a fall on the outstretched hand Other mechanisms Palmer flexion,twisting injuries Slide 13 Mechanism of injury High energy forces Results in carpal bone fractures or ligamentous disruption of both extrinsic and extrinsic ligaments and perilunate dislocation Low energy forces results in minor injuries such as sprains Slide 14 Imaging Plain radiographs: multiple views necessary: Anteroposterior Lateral Oblique Clenched-fist AP Radial and ulnar deviation Slide 15 Imaging Gilula's lines. A. AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B. Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation.. Slide 16 Imaging Standard scaphoid views detect most carpal injuries PA x-ray with wrist neutral and in ulnar deviation elongates scaphoid to better visualize MRI scans are useful in detecting occult fractures, AVN of the carpal bones, and ligamentous injuries. Perilunate dislocations are easily missed if the continuity of Gilula's line is not assessed. Slide 17 General Principles of Treatment Carefully evaluate x-rays for subtle fractures and/or evidence of carpal instability. Reduce and immobilize scaphoid fractures or perilunate injuries pending definitive treatment. Diagnose and appropriately treat ligament and bony injuries. Slide 18 Lunate fractures Rare