Scanning the wrist for ligament injuries

Abstract

To understand the pathology which may occur following an injury to the wrist, this presentation will review the anatomy and biomechanics of this joint. The biomechanics of wrist injuries are as follows Weightbearing injuries which may be sustained weightlifting or in gymnastics where there is increased axial loading or where the wrist is extended and radially deviated, may result in volar carpal ligament injuries. Twisting injuries during wrestling and again gymnastics where there is excessive pronation or supination of the wrist may affect the TFCC. Impact injuries such as a fall onto the outstretched hand - FOOSH - can result in scapho-lunate, lunotriquetral and or palmar radiocarpal ligament rupture, a TFCC tear or a strain of the dorsal radiocarpal ligament. (Anderson, Read, 2008) All these ligaments which have been listed are easily seen with ultrasound. A detailed history is imperative prior to scanning the wrist. Specific tests can also be useful determining which ligaments may be injured prior to scanning such as Watsons test. Injuries to intrinsic ligaments such as the scapholunate ligament can be classified into 3 different grades. Grade 1 is a stable injury with only mild stretching of the joint from radial to ulnar deviation. Grade 2 is a tear of the central and dorsal components of the ligament leading to widening of the joint from radial to ulnar deviation. Grade 3 is a tear of all 3 regions of the ligament leading to not only widening of the joint but malalignment of the joint. A partial tear or strain of an extrinsic ligament will appear as a thickened, hypoechoic, but in tact ligament. A full thickness tear will appear as an anechoic defect in the ligament. The ultrasound appearances and technique for scanning these ligaments as well as ligamentous pathology will be reviewed in this presentation.