Radiologic imaging of wrist, hand, and finger injuries

Abstract

Acute and overuse injuries to the wrist and hand occur with a higher frequency in specific sports utilizing the hand and wrist. Wrist lesions may sometimes be difficult to diagnose on physical examination. Proper clinical and radiological diagnosis of injuries in this region requires a thorough knowledge of the anatomy and biomechanics of the wrist. Knowledge of the sports activity aids in the diagnosis of these injuries as sporting activities may be associated with specific injury patterns. Important acute injuries that should not to be missed are any type of carpal dislocation especially lunate and perilunate dislocation. Special considerations are made in preadolescent and adolescent athletes, as hand and wrist injuries are more common in these age groups compared to adults. Fractures are primarily examined radiographically; complex intra-articular fracture components are evaluated with multiplanar or cone beam CT. Despite the fact that nondisplaced fractures are a radiological challenge and occult fractures are frequent, radiography remains the first imaging modality in the initial evaluation and follow-up. If clinically suspected, additional examinations are mandatory, whether repeated radiographs after 1 week of immobilization, or bone scintigraphy, or MRI. Because of its sensitivity, specificity, absence of radiation exposure, and lower cost, MRI is the imaging modality of choice over nuclear imaging techniques for depiction of radiographic occult fractures. Multislice CT or cone beam CT with its high spatial resolution and multiplanar two-dimensional reconstructions in three orthogonal imaging planes improves visualization and characterization of the fracture line and the amount of displacement and angulation of the fracture fragments or staging. AVN is studied with contrast-enhanced MRI. Stress fractures are lately recognized on radiographs related to endosteal spongious callus with bandlike increased bone density. On MRI they are early and easily demonstrated. On MRI, the presence of edema without a visible fracture line may represent a bone bruise or a stress reaction recognized as forestage of stress fracture. About 10 % of carpal injuries result in instability. Clinical findings are often nonspecific. Imaging is important as diagnosis of a significant injury will dictate treatment. Wrist instability most commonly results from ligamentous disruption between bones of the proximal carpal row. The presence or absence of carpal instability on radiographs depends on the association between intrinsic and extrinsic ligament tears – even partial ones – rather than on the presence of intrinsic ligament tears alone, even when the tears are complete. An instability pattern in the radiocarpal or midcarpal joint with carpal dissociation is called carpal instability dissociative (CID); carpal instability without carpal dissociation is known as carpal instability nondissociative (CIND). Imaging evaluation of patients with ulnar-sided wrist pain is mandatory because of its broad clinical differential diagnosis comprising DRUJ, TFCC, LT, and ECU lesions, pisotriquetral instability, ulnoradial impingement, and ulnocarpal impaction-abutment. Radiographs demonstrate the variance of the ulna, distal radioulnar joint dislocations, and signs of chronic ulnar impaction-abutment syndrome related to ulna majus or ulnoradial impingement related to ulna minus. TFCC evaluation is done with MRI. Overuse tendon injuries are more frequent compared to acute tendon lesions. Inflammation of tendon sheaths is the most frequent abnormality found on US of the wrist. Ultrasound or MRI is only indicated in chronic recidivism. Tendon rupture and its severity can also be detected on US. Peripheral nerve injuries of the upper extremity in sports are rarely reported; however, they can be most debilitating to an athlete. Peripheral nerves are prone to various types of injury in sport owing to their superficial location. Most commonly, direct blows or repetitive microtrauma is implicated as a mechanism of injury. Hypothenar hammer syndrome (HHS) is related to repetitive trauma of the ulnar-volar aspect of the wrist. Doppler ultrasound along is an accurate noninvasive test to determine the presence, size, and extent of HHS. Bicyclists develop ulnar nerve impingement at Guyon’s canal.