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Imaging in sports medicine: hand and wrist
European Journal of Radiology 26 (1997) 2 – 15
Imaging in sports medicine: hand and wrist Andreas Heuck a,*, Harald Bone´l a, Axel Sta¨bler a, Rainer Schmitt b a
Department of Diagnostic Radiology, Klinikum Großhadern, Uni6ersity of Munich, Marchioninistraße 15, D-81377 Mu¨nchen, Germany b Department of Diagnostic Radiology, Uni6ersity of Erlangen, Nu¨rnberg, Maximiliansplatz 1, D-91054 Erlangen, Germany Received 29 January 1997; received in revised form 30 January 1997; accepted 30 January 1997
Abstract Sports-related injuries of the hand and wrist include lesions of the bones, joints, ligaments, tendons and muscles. In many cases, radiologic imaging procedures are indispensible for the depiction, localization and accurate diagnosis of these lesions. This article reviews the role and potential of current imaging modalities such as conventional radiography, fluoroscopic examinations, arthrography, computed tomography (CT), ultrasound, and magnetic resonance (MR) imaging for the diagnostic work-up of typical osseous and soft tissue injuries in sports medicine. © 1997 Elsevier Science Ireland Ltd. Keywords: Hand injuries; Hand MR; Hand radiography; Wrist; Joints injuries; Athletic injuries; Images
1. Introduction Sport injuries to the hand and wrist include a wide range of pathology which may involve bones, joints, tendons, ligaments, and muscles or a combination of those. For the radiological diagnosis of sports-related injuries, a profound understanding of the main principles of anatomy, physiologic movement and sports-related stress on hand and wrist is required in addition to the knowledge, which imaging modality should be used to achieve proper detection, localization, and characterization of a suspected injury. Throwing, twisting, weightbearing and impact are the main four mechanisms of injury to the wrist. Ulnar deviation and rotational stress in overhead sports, such as tennis, bear the risk of throwing injuries. A twisting injury can result from ligament disruption during any forceful and quick rotation of the wrist during any sport. Axial compressive forces, that are most often associated with weightlifting or gymnastics, can cause weightbearing injuries. A fall on the outstretched arm
* Corresponding author. Tel.: +49 89 70953250: fax: + 49 89 70958822.
or direct force sustained during a contact sport often lead to impact injuries [1]. The focus of this paper is to outline the actual spectrum of imaging modalities useful for the diagnostic workup of typically sports-related bone and soft tissue lesions of the hand and wrist region.
2. Imaging modalities Before imaging is performed, the radiologist needs to know the patients history, clinical findings, and specific questions of the referring physician. Only on the basis of this information an adequate imaging approach can be tailored allowing for a fast and sensitive lesion depiction and a specific diagnosis which supports the clinician in his therapeutic considerations.
2.1. Standard radiography The most common question in patients with sportsrelated injuries relates to the presence or absence of fracture. In these cases, the first-line imaging method will be radiographs in order to depict or rule out traumatic osseous lesions.
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Standard projections of the post-traumatic hand and wrist include dorso-palmar and lateral views in neutral position. Depending on the patient’s history and clinical exam, a limited area, e.g. the wrist or one finger, may be selected for exposure, instead of the whole hand. Fractures of the distal radius and ulna as well as those of the metacarpal and phalangeal bones are commonly evident on standard projections (Fig. 1 and Fig. 2). Fractures of the carpal bones are less often accurately identified on standard films (Fig. 3). Therefore, if the clinical exam is suggestive of a fracture while standard views are not suggestive or equivocal, additional views are applicable. Static carpal instabilities such as the dorsal and volar intercalated segmental instabilities (DISI and VISI) and chronic disruption of the carpus (SLAC wrist) and others (Fig. 4) can also be frequently
Fig. 2. Fracture of the fourth metacarpal bone in a 34 year old karate fighter.
diagnosed on standard views [2–4]. A number of additional views have been described for the radiographic work-up of traumatic bone lesions of the hand and wrist. To further evaluate suspected lesions of the tubular bones (distal radius and ulna, metacarpals, phalanges), 30–45° oblique views are recommended. For the sensitive detection of carpal fractures oblique views may also be helpful, but various special projections have been established [5,6]. As the scaphoid is the most commonly injured carpal bone, the four scaphoid views are frequently performed to detect fractures which are not apparent on the standard views. Although digital radiography today gives a better impression of the soft tissue, only major structures can be seen. The impact towards ligamentous functionality is achieved by indirect signs, such as the scapho-lunear bone dissociation in injuries of the scapholunate ligament (SL) (Fig. 5).
2.2. Con6entional and computed tomography
Fig. 1. Fracture of the distal radius (Colles fracture) and the ulnar styloid resulting from a fall in ice-skating. (a) Dorso-palmar view and (b) lateral view.
Conventional and computed tomography (CT) are frequently used for the detection of fractures, that are non-apparent on plain films. Despite the fact, that conventional tomography has the potential to answer most diagnostic questions concerning the bony structures of the hand and wrist, CT has gained more clinical importance. The possibility to acquire multiple contiguous sections with high resolution in a short time, to perform multiplanar image reconstruction, and to obtain addi-
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Fig. 4. Palmar lunate dorsal perilunate luxation in addition to fracture of the radial styloid and triquetrum. (a) Dorso-palmar view: triangular shape of the lunate with pathologic overlap of the capitate and hamate and (b) lateral view: note the palmar rotation of the lunate and the dorsal position of the capitate.
Fig. 3. Scaphoid fracture as a result of a fall from the bicycle on the outstretched right arm. (a) Dorso-palmar view: the fracture is not evident and (b) oblique view in 45° supination: clear delineation of the fracture line (arrows).
tional information about adjacent soft tissues are the likely reason for the increasing numbers of CTs of the wrist. Also, the opportunity to perform 3D reconstructions in selected cases bears some potential for diagnosis and for planning of surgery. Today, CT exams are used in addition to conventional studies to further work-up unclear wrist pathologies if MRI is unavailable. CT is especially useful to detect or exclude occult fractures (Fig. 6), to document the extent of fractures for staging purposes, and to determine subluxation and luxation of the wrist as well as malrotation of the radius and ulna. Also, complete ruptures of major tendons may be identified. Finally, loose bodies of the joint, such as bony or cartilaginous fragments can be identified and localized.
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The CT exam is performed using contiguous slices with a thickness of 2 mm, and a high resolution algorithm. For examination of the carpal tunnel and the distal radioulnar joint, the axial slice orientation is preferred. Scaphoid fractures are best detected on thin slices parallel to the scaphoid axis. In unclear post traumatic chronic wrist pain, additional information is
Fig. 6. Axial CT image displaying a fracture of the hamulus of the hamate which was not depicted on plain films.
obtained in sagittal sections parallel to the forearm [7]. As standard radiographs usually suffice for the analysis of the metacarpus and fingers, CT examination of this region is performed less often. Most of the time, the axial orientation is preferred.
2.3. Fluoroscopy The main advantage of fluoroscopy over static imaging is the acquisition of real-time functional and stress images (Fig. 5b). Fluoroscopic cinematography is especially useful for the localization and quantification of dynamic instabilities and luxations. Moreover, the function of stabilized fractures can be analyzed.
2.4. Arthrography
Fig. 5. Increased distance between the scaphoid and lunate indicating a rupture of the scapho-lunate (SL) ligament. (a) dorso-palmar standard projection suggests SL dissociation and (b) fluoroscopic stress view: proof of SL-dissociation.
Arthrographic studies of the wrist and hand allow evaluation of articular cartilage, ligaments, joint compartments, and the triangular fibrocartilage complex [8]. Lesions to these structures are depicted by defects in their surface or by contrast flow between two joint compartments, that are normally separated (Fig. 7). Injection of the three main compartments, including the distal radioulnar, radiocarpal and mediocarpal compartments, has been established as the standard technique for wrist arthrography. However, single compartment arthrograms of the radiocarpal joint have been shown to have a false-negative rate of only 2% for complete and 10% for partial tears of the interosseous ligaments [9]. Therefore, the number of injections and initial injection site should be adapted to the clinical indication and suspected pathology. Arthrography of
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the metacarpophalangeal and interdigital joints are performed less often, as fewer applications exist [8]. Limitations of the examination are the painful and invasive nature of arthrography, and potential consecutive risks. Even low-osmolar contrast agent may cause irritation and swelling as part of a chemical synovitis, and the risk of joint infection can never be completely be nullified, although it is very low.
2.5. Ultrasound While ultrasound (US) is generally not helpful in the evaluation of osseous pathology, it provides valuable information in the depiction of sports-related soft tissue lesions. The two major indications for US are muscle injuries and tendinous lesions [10 – 14]. In addition, joint effusions, ganglia, ruptures of the ligaments, such as the ulnar collateral ligament, are identified in ultrasound. Tendon movement in the tendon sheaths can be observed real-time. Nearly all arteries of the hand and
Fig. 8. Longitudinal US scan of the extensor pollicis longus tendon. Discontinuity of the tendon (arrows) on the level of the proximal phalanx (GP) indicating rupture.
wrist can be accessed very well by Doppler US. However, because of their tiny nature and close relationship to bony surfaces, interosseous ligaments of the wrist cannot be satisfactory assessed. Similarly, due to the limited sonographic access and spatial resolution, US images of the triangular fibrocartilagineous complex (TFCC) do not provide enough information on its internal structure to allow a final diagnosis (Fig. 8). To obtain sufficient spatial resolution, linear transducers of high frequency of 7.5 and 10 MHz are required. Because most relevant structures of the hand and wrist, such as muscles and tendons, are located superficially, image quality may be substantially improved by the use of a stand-off pad. Longitudinal and transverse scanning of the area of interest must be performed, and care must be taken to avoid erroneous interpretation of US findings due to technical factors, e.g. hyperechoic zones of tendons caused by non-orthogonal scanning and mimicking partial tears or tendinitis.
2.6. Magnetic resonance imaging
Fig. 7. Arthrography of the wrist. (a) Rupture of the SL-ligament indicated by contrast material extending through the radiolunate joint space from the mediocarpal to the radiocarpal compartment and (b) small tear of the TFCC (arrows): contrast material extending from the radiocarpal compartment into the distal radioulnar joint space.
Magnetic resonance imaging (MRI) provides the most comprehensive information on the wrist, including bone marrow and soft tissues, such as ligaments, tendons and muscles [15–17]. In principle, with MRI, a great number of sports-related damages to the hand and wrist can be depicted in a non-invasive and accurate fashion [14,17]. The indications of MRI are confined to those pathologies of the soft tissue and bones, which cannot be conclusively diagnosed by either conventional techniques, ultrasound or CT. This includes ligamentous lesions, occult fracture, avascular necrosis, as well as tendon, nerve and muscle injuries. Furthermore, TFCC lesions are best identified on MRI exams [18]. By the use of intravenous contrast agents, additional information on vitality and inflammation can be obtained. The standard examination of the wrist should include T1-weighted axial and coronal images as well as T2weighted or STIR sequences in either axial or coronal
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Fig. 9. Biker, 31 year-old, with a bone bruise of the scaphoid. In MR imaging, the distal scaphoid shows a decreased signal intensity in the T1-weighted spin-echo sequence (a), in the T2-weighted sequence the signal is increased (b). Conventional radiographs were normal. The clinical symptoms vanished within 2 weeks without any surgical intervention.
orientation. A slice thickness of 3 mm or less in the axial and 1–2 mm in the coronal planes is preferred. Thicker slices might be less diagnostic and less accurate in depicting the underlying pathology [17,18]. Based on the patient’s history and clinical exam, additional studies might include sagittal or oblique planes. Metacarpus and fingers are preferably scanned using 2 mm thick sagittal and 3 mm thick axial slices. Application of contrast media is usually not required in acute traumatic conditions. Instead, it is necessary for long term control of vitality, e.g. after scaphoid fractures, and for depicting reparative or proliferative post traumatic changes, e.g. in the triangular fibrocartilage complex, or reactive or inflammatory synovial proliferation and enhancement.
3. Osseous lesions Most sports related fractures occur in the scaphoid and triquetral bones, whereas other carpal bones are rarely involved in sports injuries. The imaging impact towards osseous lesions is multiple: first aim is to detect both fractures and occult osseous lesions; accompanying soft tissue lesions, particularly of ligaments, have to be identified; long term control of fracture healing or diagnosis of prevailing pseudarthrosis is another important topic of radiologic imaging.
3.1. Fractures Simple fractures are generally revealed by plain film radiography in standard projections and with clinical correlation (Figs. 1–3). In cases with strong clinical suspicion of a fracture but unequivocal radiographic findings additional projections such as oblique views or scaphoid views may be performed to confirm the diagnosis (Fig. 3). Computed tomography is well suited to evaluate fractures not clearly evident on plain films unless the fracture line is in the plane of section (Fig. 6) [7,19].
3.2. Occult fractures and bone contusions Occult fractures are easily demonstrated on MRI exams by a line of alterated signal intensity through the bony cortex and/or marrow of the respective bone. In many instances, T1-weighted sequences already display a fracture line with decreased signal intensity (SI) compared with fatty marrow and high SI compared with cortical bone. However, fat suppressed sequences, such as STIR, reveal highest sensitivity in the detection of high SI traumatic bone marrow edema accompanying acute fractures or bone contusion (Fig. 9) [15,16,20,21].
3.3. Posttraumatic osteonecrosis The main reasons for the high incidence of posttraumatic avascular necrosis of the scaphoid are frequent
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Fig. 10. Osteonecrosis of the proximal pole of the scaphoid after scaphoid fracture. (a) In T1-weighted MR imaging, the scaphoid is depicted with decreased signal intensity and (b) after intravenous contrast, only the distal pole of the scaphoid enhances. The signal intensity of the proximal part of the scaphoid remains unchanged, indicating insufficient blood supply and avitality.
proximal pole fractures and the lack of sufficient direct blood supply to the proximal part of this bone. Prompt diagnosis and treatment of necrosis is important to minimize complications. Conventional radiographs lag behind the onset of diagnosis and therefore cannot be considered as sensitive. However, MRI is the procedure of choice for the early diagnosis of carpal avascular necrosis, as it is at least as sensitive as bone scintigraphy while being more specific and providing better spatial resolution [22,23]. The most common MR appearance of avascular necrosis of the scaphoid is a decreased SI in the proximal pole on both T1- and T2-weighted sequences. Localized fluid accumulation and marrow edema of the proximal pole may also be observed on T2 weighted images. Based on these findings the sensitivity for scaphoid osteonecrosis is reported to be 87.5%, the specificity 100% [22,23]. Sensitivity may be further increased by intravenous application of gadolinium chelates when the necrotic proximal pole is displayed without enhancement while the viable distal pole shows contrast uptake (Fig. 10).
the joint or tendon sheath, which is sometimes only depicted in tomographic or MRI exams. Posttraumatic bone cysts are depicted in radiographs or CT as a localized loss of structure of the spongy bone with a distinct sclerosis at the border. Quite often, the trauma is not remembered. Subchondral cysts, however, are also often found in degenerative joint disease of the wrist [24].
3.4. Bone cysts and intraosseous ganglia
The biomechanical design of the wrist ensures that a minimum number of ligaments maintain stability throughout a wide range of motion. Many schemes have been developed to explain carpal instabilities. The following is a simplified approach, which reflects a compromise of several authors’ views [27–29]. The main stability and alignment of the wrist is maintained by the palmar ligaments. Dorsal and in-
Bone cysts are more frequently found after trauma or as a result of posttraumatic degenerative joint disease and should not be confused with the channels of nutricial blood vessels in carpal bones. There is no pathologic value to the bone cyst itself. Intraosseous ganglia are cystic lesions characterized by a connecting duct to
3.5. Growth plate lesions In chronically stressed wrists, frequently abnormalities of the growth plate are found in MRI: physeal cartilage extension into the metaphysis seem to represent a healing sign of otherwise occult, horizontal fractures. Chronic repetitive stress on adolescent wrists causes localized growth disturbance of the distal radius, resulting in ulnar plus variance. Permanent sequelae may result even in asymptomatic individuals [25,26].
4. Instabilities and ligamentous injuries
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Fig. 11. Disrupture of the triangular fibrocartilage complex (TFCC) in a 35 year old soccer player. (a) The T1-weighted coronal MR image displays increased signal intensity in the base of the TFCC. (b) After contrast, there is enhancement of the reparative tissue and the rupture of the ulnar ligaments can be seen more obviously.
terosseous ligaments provide additional support. In sports activities, the resultant forces are distributed along the longitudinal axis of the wrist. Most of these axial loading forces project along the long axis of capitate, lunate, and radius. In the neutral ulnar variant, approximately 80% of axial forces are transmitted through the lunate to the radius, while most of the remaining forces are transmitted through the lunate to the ulna. In ulnar or radial deviation, the remaining carpal bones and ligaments balance the axial or longitudinal loading forces. The scaphoid serves as a mobile link between the distal and proximal carpal rows.
4.1.1. Static instability This term refers to changes in carpal alignment. Usually, static instabilities are associated with palmarflexion, dorsiflexion or ulnar migration of the lunate. This disalignment cannot be actively reversed by the patient. Carefully performed routine radiographs display an abnormal carpal configuration (Fig. 4) [2–4].
4.1. Carpal instabilities
4.1.2. Dynamic instability With certain ligaments torn or attenuated, the wrist maintains a normal anatomic position until subjected to an axial loading force. In dynamic instability, the wrist is normally aligned when non-stressed, but collapses into an unstable configuration when loaded with axial force. A fluoroscopic stress exam usually reveals this pathologic condition.
In pathologic condition, the dominant axial loading forces result in wrist shortening. Wrist shortening can be described as a proximal migration of the capitate and occur gradually over time or secondary to severe, acute trauma. Acute fractures and dislocations result from severe and sudden, axial loading forces, for example from a fall on the outstretched hand. Chronic or more subtle acute injuries in particular involve interosseous and volar ligaments. A complex pattern of carpal instabilities results from partial or complete rupture of single or multiple ligaments. Despite the considerable variability of classification systems, a few terms are relatively universally recognized and therefore described.
4.1.3. Midcarpal instabilities Midcarpal instabilities occur between the proximal and the distal carpal rows. The dorsal intercalated segmental instability (DISI) is characterized by dorsal rotation, the volar or palmar intercalated segmental instability (VISI/PISI) by palmar rotation of the lunate. A fall on the outstretched hand is one of the most common accidents in sport leading to carpal instability. The resultant forces may suffice to produce a radius fracture combined with a lunate or perilunate dislocation or a scaphoid fracture (Fig. 4). In the process of healing, quite frequently, residual dorsiflexion of an old distal radius fracture fragment is associated with dynamic DISI without scapholunate dissociation.
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However, even if the force is not sufficient to cause the bony injury mentioned above, tears of the radioscapholunate, dorsal radiocarpal or interosseous scapholunate ligaments can occur. The weakest link between the radius and proximal carpal row is the radioscapholunate ligament (RSL). For this reason, the most common mid-wrist instability, the DISI, often is accompanied by scapho-lunate dissociation. VISI is the more uncommon form of the midcarpal instability. Patients frequently complain of a painful clunk that occurs during sports activities involving pronation and ulnar deviation of the wrist. DISI and VISI configurations can be diagnosed on standard lateral projections of the wrist [2,4]. MRI also constantly shows the radioscapholunate, lunotriquetral, and the interosseous ligaments projecting to the capitate on coronal images with a slice thickness of 1–2 mm [15].
4.1.4. Lateral and medial carpal instabilities This classification is based on the functional concept of three carpal columns. Lateral carpal instability refers to instability between the lateral column, formed by the scaphoid, and the central column, which consists of the lunate-capitatetrapezoid-trapezium row. Scapholunate dissociation, scaphocapitate diastasis, and scaphotrapezoid instabilities are major subsets of this group. As the lateral column controls lunate volarflexion, lateral carpal instability is typically associated with a DISI. Medial carpal instabilities are caused by dissociation of the medial column, which is formed by the triquetum, and the central column. Triquetrolunate and triquetohamate dissociation are the major subsets of this entity. The medial column restrains the dorsal flexion of the lunate. Therefore, medial carpal instabilities typically result in VISI. If standard radiographs are not diagnostic and the nature of the instability is unclear, a dynamic MRI exam is mostly suggestive of the lesion [27]. 4.2. Luxations and subluxations 4.2.1. Scapholunate ad6anced collapse (SLAC) The scapholunate advanced collapse (SLAC) is the most common form of human wrist degenerative arthritis. It is characterized by a rotary subluxation of the scaphoid, in which its proximal articular surface is displaced from its normal elliptic fossa in the radius. The progressive loss of scaphoid cartilage results in progressive scaphoid collapse. Because of the further increase in capitolunate load, the capitate migrates proximally to the scapholunate gap, and the lunate translocates ulnarly. The wrist shortening can cause proximal migration of the transverse carpal ligament and thus may result in carpal tunnel syndrome. SLAC
wrists are easily diagnosed on plain films. In addition, MRI contributes to detection of associated lesions and therapy planning.
4.2.2. Hand Martial sports, basketball and volleyball put extra stress on metacarpus and fingers. Frequently luxations and subluxations of the metacarpals and fingers result. Plain radiographs in two projections depict these lesions very well. For demonstration of ligamental lesions, ultrasound and MRI provide more information. MRI also depicts accompanying lesions, of e.g. bones and tendons, best. 4.3. Triangular fibrocartilage complex (TFCC) The normal TFCC includes the articular disk, the meniscal homologue, and the stabilizing ligaments of this functional unit: the palmar and dorsal radio-ulnar ligaments, the ulnar collateral ligament, the sheath of the ulnar extensor, and the ulno-lunate and-triquetral ligaments [30–32]. The TFCC has three major functions [31]: (a) it bears up to 20% of the axial load of the wrist; (b) it stabilizes the distal radio-ulnar joint; (c) it firms the ulnocarpal joint. For TFCC evaluation, arthrography has been considered a standard technique (Fig. 7b). No obvious advantage of post-arthrographic CT over conventional arthography has been found so far [4]. By using thin slice techniques a suitable spatial resolution has been achieved in standard MRI exams [18]. MR has emerged as a precise, non-invasive technique with an accuracy of 95%, using open surgery or arthroscopy as a gold standard (Fig. 11) [4,32]. Thus, therapy can be planned more easily without preceding invasive diagnostic measures [3,30,32]. Considering the lower cost of the three compartment arthrogram in comparison to MRI in the aspect of additional information gained by an MRI exam, no clear decision in favor of arthrography or MRI can be made [8]. In MRI, the normal articular disc appears as a thick band of low signal intensity. In the sagittal planes, the disc appears biconcave, in the coronal triangular. The peripheral margins appear thicker and stronger than the central zone [30,31]. The meniscal homologue represents a region of ill defined, irregular, more or less dense fibrous tissue. Both the meniscal homologue and the ulnar extensor tendon subsheath appear inconstant on MRI studies. The collateral ulnotriquetral and ulnolunate ligaments can constantly be identified in sagittal thin sections. Degenerative changes of the articular disc appear as signal alterations, mostly starting from the lateral aspect of the TFCC. Tears of the TFCC are visualized in MRI as discontinuities and fragmentation of the low signal intensity band representing the articu-
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Fig. 12. Longitudinal T1-weighted MR image of D V. Increased signal intensity and thickening of the extensor tendon indicates a partial tear. Note that there is no retraction of the proximal and distal part of the tendon.
lar disk and the contour of the disk becomes irregular in shape. The overall sensitivity of MRI in comparison to arthroscopy is excellent (1.0), also the specificity (0.93) [30,32]. However, quite often in the asymptomatic adult, signal alterations in the more central part of the TFCC make the differentiation of a recent traumatic lesion from a traumatic lesion more difficult. If the TFCC was damaged in recent trauma, the region enhances after intravenous contrast. This enhancement represents reparative tissue, providing another clue on the differential of abnormal signal intensity. Intravenous contrast is therefore recommended in unclear cases (Fig. 10).
surgical intervention is advocated to allow healing, otherwise immobilization may suffice [37]. Clinical exam and conventional radiographs in additional stress views allow the diagnosis of UCL rupture, however, the displacement is not depicted. Sonographic exams allow a reliable diagnosis of displacement in 86% [37]. In a preliminary MR imaging study, UCL displacement could be depicted with a sensitivity of 100% and a specificity of 94% [38]. Therefore, both US and MRI may add important information particularly in patients with ambiguous clinical signs, for whom surgical treatment should be discussed.
5. Tendinous lesions
4.4. Ulnar collateral ligament of the thumb Traumatic abduction of the thumb is most frequently seen in skiers and gamekeepers. The resulting lesion of the ulnar collateral ligament (UCL) in the metacarpophalangeal joint is therefore often referred to as skier’s or gamekeeper’s thumb and classified according to Stener [33]. The anatomic position of the UCL is underneath the adductor/extensor aponeurosis of the thumb, where it extends from the dorso-ulnar aspect of the metacarpal to the volar-ulnar side of the base of the proximal phalanx. Most of the time, the ligamentous rupture is found in the distal, phalangeal portion. The proximal part retracts, and often there is interposition of the aponeurosis between the proximal part of the UCL and its insertion at the proximal phalanx [34 – 37]. In situation of displacement of the proximal part of the UCL,
Sports related tendinous lesions of the hand and wrist may affect the flexor or the extensor group [1,39].
5.1. Tendon rupture Complete tendon ruptures are rare and usually occur with acute hyperextension or hyperflexion trauma or as a result of maximum mechanical stress. Frequently, alterations of the respective tendon, such as myxoid degeneration or tendinitis, are found as predisposing factors at the rupture site. While the majority of complete tendon ruptures can be diagnosed clinically, the exact location and extent of a tear may be difficult to determine and, therefore, requires preoperative imaging assessment [39]. Partial tendon tears are related to acute mechanical stress or chronic trauma and are more common than
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Fig. 13. Tenovaginitis stenosans de Quervain in a 38 year-old tennis player. The tendon sheaths of the extensor pollicis brevis and of the abductor pollicis longus (arrows) are thickened (a) and enhance after contrast (b).
complete ruptures. As the clinical diagnosis may be difficult, imaging techniques are needed for further evaluation and the establishment of diagnosis. Adhesions and scar tissue formation around a repaired tendon are frequent postoperative complications that lead to functional impairment. Differentiation between re-rupture and scar formation may also be difficult on clinical grounds. Standard radiographs are important to prove or rule out tendon avulsion. Ultrasound is useful in identifying the site of complete tendon ruptures (Fig. 8), especially when the defect is filled by an organizing blood clot and creates difficulties in clinical diagnosis [40]. Beside an exact location, the distance between the two parts of the torn tendon can be measured by ultrasound and may help to determine the type of treatment to be adapted. Acute partial ruptures may variously present as a defect of the tendon contour, a localized thickening of the tendon and/or intra- or peritendinous hematoma. Chronic partial tears present as a localized inhomogeneous, hypoechoic thickening of the tendon. MRI excellently depicts the pathologic tendinous anatomy of the wrist and hand while simultaneously displaying bony and other soft tissue structures [41]. Complete tendon ruptures are seen as a gap in the continuity of the low SI tendon. Depending on the material which fills the gap (fluid, hematoma, or repair tissue) its SI in T1- and T2-weighted images may vary but lies always considerably above that of normal tendons. Incomplete ruptures (Fig. 12) or chronic tears are depicted by MRI as irregular thinning or thickening of the tendon, sometimes with linear areas of high SI on long TR/TE images, within the substance of the tendon [42]. Post surgical scarring can be accurately differentiated from tendon re-rupture by MRI as in
these cases it shows irregularity of the tendon contour and low SI scar tissue. Computed tomography may also depict complete tears with a gap of the tendon and incomplete tears with focal irregularities, however, it is considered less sensitive and specific than MRI.
5.2. Tendinitis, tenosyno6itis and other o6eruse syndromes Tendinitis and tenosynovitis are common findings in overuse syndromes of athletes participating in racquet sports, rowing and weight lifting [43–45]. A common site of tenosynovitis in racquet sports is the first extensor compartment involving the abductor pollicis longus and extensor pollicis brevis tendons and sheaths at the level of the radial styloid. This condition is known as de Quervain’s tenosynovitis (Fig. 13). Typical clinical findings are pain and swelling in the anatomic snuff box (tabatie`re), in late stages associated with entrapment or limited extension of the thumb. Other overuse syndromes leading to tendinitis and tenosynovitis involve the extensor carpi radialis longus and brevis tendons (frequently associated with carpal boss), the extensor carpi ulnaris tendon in the region of the fibroosseous tunnel, and most frequently the flexor carpi ulnaris and flexor carpi radialis tendons. The intersection syndrome is characterized by irritation of a bursa located at the intersection of the extensor carpi radialis longus and brevis and the abductor pollicis longus. Clinical symptoms are pain, weak grasp, and crepitation (squeaker’s wrist). Radiographs are performed to rule out avulsion injury or calcific tendinitis. US may be useful in depicting pathology of tendons or tendon sheaths, particularly the fluid filled tendon sheaths in acute tenosynovitis.
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Fig. 16. Hematoma in the pronator quadratus muscle in a 17 year-old inline skater who didn’t wear his wrist protection gear. There is increased signal intensity in the T2-weighted turbo-spin echo sequence.
Fig. 14. MR imaging of a pulley injury in a sport climber. (a) Schematic drawing of the annular (A1–A5) and cruciate (C1 – C3) pulleys of the finger. (b) T1-weighted longitudinal image of a normal ring finger. The black flexor tendon is closely related to the palmar surface of the proximal phalanx. (c) Proton-density weighted MR image of the ring finger in a climber with a A2 pulley injury. Note the increased distance between the tendons and bone (arrowheads) and a small ganglion cyst extending from the flexor tendon sheath (arrows). (d) T2-weighted image, same as in (c). High signal intensity between flexor tendons and bone (arrow heads) indicates edema and hemorrhage as a result of A2 pulley tear. High signal intensity of the ganglion cyst.
However, the distinction between partial chronic rupture and chronic tendinitis is difficult by sonographic criteria alone. Therefore, MRI should be employed for a more detailed assessment. Acute tenosynovitis is displayed with high SI of fluid on T2-weighted or STIR
Fig. 15. Axial T2-weighted MR image of the carpal tunnel: transient edema of the median nerve (arrow) in a 17 year-old inline skater. Hyposensitivity of the finger tips on clinical exam.
images distending the synovial sheaths and, if associated with tendinitis, with swelling and high SI within the tendon substance. After application of Gadolinium contrast agents the tendon sheath may enhance due to hyperaemia of the tenosynovium. Chronic tenosynovitis is depicted as tendon and synovial sheath thickening with or without fluid in the sheath and peritendinous edema. Contrast enhancement may be mild to very intense, depending on the degree of inflammatory or proliferative reactions. In late stages, fibrotic changes without significant contrast uptake may be predominant. Thus, contrast enhanced MRI allows for determination of the disease activity [46].
5.3. Pulley injuries The commonest acute hand injury in competition rock climbers affects the A2 pulley of the flexor tendon sheath of the ring or middle finger [45,47,48]; other pulleys are less frequently involved [49]. The annular pulleys (A1–A5) are strong, ring-like fibrous structures which arise from and inseparably merge with the periosteum of the phalanges and strenghten the flexor tendon sheaths [45,47,48]. The rupture most often occurs while climbers are holding or pulling up on a small hold with one or two fingers (usually the third and fourth finger). Clinical findings are swelling and increased ‘bow-stringing’ of the flexor tendon on resisted flexion. In high resolution MRI the normal flexor tendons are displayed with low SI in very close relation to the phalangeal bones (Fig. 14). As the pulleys are part of the flexor tendon sheath, they cannot generally be identified as separate structures. However, increased distance between the flexor tendon and the phalanx together with increased SI between the two due to edema and hemorrhage can be considered as sensitive
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and reliable indicators for acute annular pulley rupture (Fig. 14).
6. Soft tissue lesions
6.1. Post-traumatic ner6e impairment Nerve impairment may be found in acute or chronic injury or overuse syndromes [50,51]. The most common site of nerve impairment in the hand and wrist region is the carpal tunnel, whereas the ulnar tunnel (Guyon’s canal) is less often involved. In acute injury, nerve compression by displaced fracture fragments, hematoma or soft tissue edema may result in neurologic symptoms typical for the nerve involved. Also, chronic injuries or overuse reactions associated with thickening of the flexor retinaculum, flexor tendons and tendon sheaths, or even with hypertrophy and more distal extension of the flexor muscles (e.g. in rock climbers) may lead to transient sensory or motoric deficits. While CT has proven to be the method of choice in the work-up of osseous carpal stenosis [50], US and MRI are most valuable imaging modalities for detecting alterations of the median nerve and underlying soft tissue alterations [51 – 53] (Fig. 15). The most frequent finding of carpal tunnel syndrome (CTS) are edema and deformation of the median nerve due to mechanical compression. Other soft tissue findings may include tenosynovitis, tendinitis and interstitial edema.
6.2. Muscular lesions Although muscular trauma frequently occurs in sports injuries, only very little has been reported on muscular lesions of the hand and wrist region. Most sports-related muscle injuries are located in the thigh and lower leg and comprise of a variety of different lesions ranging from minor strains to severe tears including necrosis and hematoma [54,55]. However, even if muscular injuries of the hand appear relatively rare, the resulting lesions can be assumed to be very similar to other locations. Radiologic techniques which allow for detection of muscle injuries include US [10,14], computed tomography [54], and MRI [55 – 58]. The US appearance of traumatic muscle lesions depends on their extent. Simple strains or partial tears cannot be accurately detected, but a hypo- or anechoic hematoma can be demonstrated as the sole evidence of an incomplete muscle tear. In extreme cases with complete muscle rupture, two muscle fragments are separated by a gap of hematoma and edema. Partial chronic muscle tears lead to fibrosis and scar with ill-defined hyperechoic regions. CT is not a very sensitive imaging modality for the proof of muscle injuries, however, severe pathologic
changes such as muscle necrosis and hematoma may be depicted [54]. In contrast, MRI has been shown to be a very sensitive and specific technique for detection and differentiation of traumatic muscular lesions. Strains can be identified by a diffuse hazy hyperintensity on T2weighted and STIR images, while partial tears usually demonstrate an additional focal area of relative hyperintensity. Associated subacute hemorrhage may be displayed with increased SI in T1-, T2-weighted and STIR images, reflecting the presence of methemoglobin. Discontinuity of the muscle and the presence of extensive hematoma and interstitial edema are reliable indicators for complete muscle tears (Fig. 16).
7. Conclusion Radiologic imaging procedures are indispensible for the depiction, localization and accurate diagnosis of most sports-related hand and wrist injuries. Conventional radiographs form the basis of hand and wrist imaging in providing important information on fractures, dislocations and some instabilities. CT is of value in the evaluation of complex and hidden carpal fractures, (sub-)luxations and malrotations and of major soft tissue lesions. Arthrography is a valuable method for the evaluation of carpal interosseous ligaments, joint capsules and the TFCC. Ultrasound displays most soft tissue lesions, such as tendon ruptures or hematoma. As no other modality, MRI allows direct visualization of both osseous and soft-tissue components of the hand and wrist. Subtle abnormalities, such as occult fractures or bone contusion, early stages of osteonecrosis, as well as injuries of tendons, ligaments and muscles may be detected very accurately, thus permitting early diagnosis.
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Imaging in sports medicine: hand and wrist Andreas Heuck a,*, Harald Bone´l a, Axel Sta¨bler a, Rainer Schmitt b a
Department of Diagnostic Radiology, Klinikum Großhadern, Uni6ersity of Munich, Marchioninistraße 15, D-81377 Mu¨nchen, Germany b Department of Diagnostic Radiology, Uni6ersity of Erlangen, Nu¨rnberg, Maximiliansplatz 1, D-91054 Erlangen, Germany Received 29 January 1997; received in revised form 30 January 1997; accepted 30 January 1997
Abstract Sports-related injuries of the hand and wrist include lesions of the bones, joints, ligaments, tendons and muscles. In many cases, radiologic imaging procedures are indispensible for the depiction, localization and accurate diagnosis of these lesions. This article reviews the role and potential of current imaging modalities such as conventional radiography, fluoroscopic examinations, arthrography, computed tomography (CT), ultrasound, and magnetic resonance (MR) imaging for the diagnostic work-up of typical osseous and soft tissue injuries in sports medicine. © 1997 Elsevier Science Ireland Ltd. Keywords: Hand injuries; Hand MR; Hand radiography; Wrist; Joints injuries; Athletic injuries; Images
1. Introduction Sport injuries to the hand and wrist include a wide range of pathology which may involve bones, joints, tendons, ligaments, and muscles or a combination of those. For the radiological diagnosis of sports-related injuries, a profound understanding of the main principles of anatomy, physiologic movement and sports-related stress on hand and wrist is required in addition to the knowledge, which imaging modality should be used to achieve proper detection, localization, and characterization of a suspected injury. Throwing, twisting, weightbearing and impact are the main four mechanisms of injury to the wrist. Ulnar deviation and rotational stress in overhead sports, such as tennis, bear the risk of throwing injuries. A twisting injury can result from ligament disruption during any forceful and quick rotation of the wrist during any sport. Axial compressive forces, that are most often associated with weightlifting or gymnastics, can cause weightbearing injuries. A fall on the outstretched arm
* Corresponding author. Tel.: +49 89 70953250: fax: + 49 89 70958822.
or direct force sustained during a contact sport often lead to impact injuries [1]. The focus of this paper is to outline the actual spectrum of imaging modalities useful for the diagnostic workup of typically sports-related bone and soft tissue lesions of the hand and wrist region.
2. Imaging modalities Before imaging is performed, the radiologist needs to know the patients history, clinical findings, and specific questions of the referring physician. Only on the basis of this information an adequate imaging approach can be tailored allowing for a fast and sensitive lesion depiction and a specific diagnosis which supports the clinician in his therapeutic considerations.
2.1. Standard radiography The most common question in patients with sportsrelated injuries relates to the presence or absence of fracture. In these cases, the first-line imaging method will be radiographs in order to depict or rule out traumatic osseous lesions.
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Standard projections of the post-traumatic hand and wrist include dorso-palmar and lateral views in neutral position. Depending on the patient’s history and clinical exam, a limited area, e.g. the wrist or one finger, may be selected for exposure, instead of the whole hand. Fractures of the distal radius and ulna as well as those of the metacarpal and phalangeal bones are commonly evident on standard projections (Fig. 1 and Fig. 2). Fractures of the carpal bones are less often accurately identified on standard films (Fig. 3). Therefore, if the clinical exam is suggestive of a fracture while standard views are not suggestive or equivocal, additional views are applicable. Static carpal instabilities such as the dorsal and volar intercalated segmental instabilities (DISI and VISI) and chronic disruption of the carpus (SLAC wrist) and others (Fig. 4) can also be frequently
Fig. 2. Fracture of the fourth metacarpal bone in a 34 year old karate fighter.
diagnosed on standard views [2–4]. A number of additional views have been described for the radiographic work-up of traumatic bone lesions of the hand and wrist. To further evaluate suspected lesions of the tubular bones (distal radius and ulna, metacarpals, phalanges), 30–45° oblique views are recommended. For the sensitive detection of carpal fractures oblique views may also be helpful, but various special projections have been established [5,6]. As the scaphoid is the most commonly injured carpal bone, the four scaphoid views are frequently performed to detect fractures which are not apparent on the standard views. Although digital radiography today gives a better impression of the soft tissue, only major structures can be seen. The impact towards ligamentous functionality is achieved by indirect signs, such as the scapho-lunear bone dissociation in injuries of the scapholunate ligament (SL) (Fig. 5).
2.2. Con6entional and computed tomography
Fig. 1. Fracture of the distal radius (Colles fracture) and the ulnar styloid resulting from a fall in ice-skating. (a) Dorso-palmar view and (b) lateral view.
Conventional and computed tomography (CT) are frequently used for the detection of fractures, that are non-apparent on plain films. Despite the fact, that conventional tomography has the potential to answer most diagnostic questions concerning the bony structures of the hand and wrist, CT has gained more clinical importance. The possibility to acquire multiple contiguous sections with high resolution in a short time, to perform multiplanar image reconstruction, and to obtain addi-
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Fig. 4. Palmar lunate dorsal perilunate luxation in addition to fracture of the radial styloid and triquetrum. (a) Dorso-palmar view: triangular shape of the lunate with pathologic overlap of the capitate and hamate and (b) lateral view: note the palmar rotation of the lunate and the dorsal position of the capitate.
Fig. 3. Scaphoid fracture as a result of a fall from the bicycle on the outstretched right arm. (a) Dorso-palmar view: the fracture is not evident and (b) oblique view in 45° supination: clear delineation of the fracture line (arrows).
tional information about adjacent soft tissues are the likely reason for the increasing numbers of CTs of the wrist. Also, the opportunity to perform 3D reconstructions in selected cases bears some potential for diagnosis and for planning of surgery. Today, CT exams are used in addition to conventional studies to further work-up unclear wrist pathologies if MRI is unavailable. CT is especially useful to detect or exclude occult fractures (Fig. 6), to document the extent of fractures for staging purposes, and to determine subluxation and luxation of the wrist as well as malrotation of the radius and ulna. Also, complete ruptures of major tendons may be identified. Finally, loose bodies of the joint, such as bony or cartilaginous fragments can be identified and localized.
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The CT exam is performed using contiguous slices with a thickness of 2 mm, and a high resolution algorithm. For examination of the carpal tunnel and the distal radioulnar joint, the axial slice orientation is preferred. Scaphoid fractures are best detected on thin slices parallel to the scaphoid axis. In unclear post traumatic chronic wrist pain, additional information is
Fig. 6. Axial CT image displaying a fracture of the hamulus of the hamate which was not depicted on plain films.
obtained in sagittal sections parallel to the forearm [7]. As standard radiographs usually suffice for the analysis of the metacarpus and fingers, CT examination of this region is performed less often. Most of the time, the axial orientation is preferred.
2.3. Fluoroscopy The main advantage of fluoroscopy over static imaging is the acquisition of real-time functional and stress images (Fig. 5b). Fluoroscopic cinematography is especially useful for the localization and quantification of dynamic instabilities and luxations. Moreover, the function of stabilized fractures can be analyzed.
2.4. Arthrography
Fig. 5. Increased distance between the scaphoid and lunate indicating a rupture of the scapho-lunate (SL) ligament. (a) dorso-palmar standard projection suggests SL dissociation and (b) fluoroscopic stress view: proof of SL-dissociation.
Arthrographic studies of the wrist and hand allow evaluation of articular cartilage, ligaments, joint compartments, and the triangular fibrocartilage complex [8]. Lesions to these structures are depicted by defects in their surface or by contrast flow between two joint compartments, that are normally separated (Fig. 7). Injection of the three main compartments, including the distal radioulnar, radiocarpal and mediocarpal compartments, has been established as the standard technique for wrist arthrography. However, single compartment arthrograms of the radiocarpal joint have been shown to have a false-negative rate of only 2% for complete and 10% for partial tears of the interosseous ligaments [9]. Therefore, the number of injections and initial injection site should be adapted to the clinical indication and suspected pathology. Arthrography of
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the metacarpophalangeal and interdigital joints are performed less often, as fewer applications exist [8]. Limitations of the examination are the painful and invasive nature of arthrography, and potential consecutive risks. Even low-osmolar contrast agent may cause irritation and swelling as part of a chemical synovitis, and the risk of joint infection can never be completely be nullified, although it is very low.
2.5. Ultrasound While ultrasound (US) is generally not helpful in the evaluation of osseous pathology, it provides valuable information in the depiction of sports-related soft tissue lesions. The two major indications for US are muscle injuries and tendinous lesions [10 – 14]. In addition, joint effusions, ganglia, ruptures of the ligaments, such as the ulnar collateral ligament, are identified in ultrasound. Tendon movement in the tendon sheaths can be observed real-time. Nearly all arteries of the hand and
Fig. 8. Longitudinal US scan of the extensor pollicis longus tendon. Discontinuity of the tendon (arrows) on the level of the proximal phalanx (GP) indicating rupture.
wrist can be accessed very well by Doppler US. However, because of their tiny nature and close relationship to bony surfaces, interosseous ligaments of the wrist cannot be satisfactory assessed. Similarly, due to the limited sonographic access and spatial resolution, US images of the triangular fibrocartilagineous complex (TFCC) do not provide enough information on its internal structure to allow a final diagnosis (Fig. 8). To obtain sufficient spatial resolution, linear transducers of high frequency of 7.5 and 10 MHz are required. Because most relevant structures of the hand and wrist, such as muscles and tendons, are located superficially, image quality may be substantially improved by the use of a stand-off pad. Longitudinal and transverse scanning of the area of interest must be performed, and care must be taken to avoid erroneous interpretation of US findings due to technical factors, e.g. hyperechoic zones of tendons caused by non-orthogonal scanning and mimicking partial tears or tendinitis.
2.6. Magnetic resonance imaging
Fig. 7. Arthrography of the wrist. (a) Rupture of the SL-ligament indicated by contrast material extending through the radiolunate joint space from the mediocarpal to the radiocarpal compartment and (b) small tear of the TFCC (arrows): contrast material extending from the radiocarpal compartment into the distal radioulnar joint space.
Magnetic resonance imaging (MRI) provides the most comprehensive information on the wrist, including bone marrow and soft tissues, such as ligaments, tendons and muscles [15–17]. In principle, with MRI, a great number of sports-related damages to the hand and wrist can be depicted in a non-invasive and accurate fashion [14,17]. The indications of MRI are confined to those pathologies of the soft tissue and bones, which cannot be conclusively diagnosed by either conventional techniques, ultrasound or CT. This includes ligamentous lesions, occult fracture, avascular necrosis, as well as tendon, nerve and muscle injuries. Furthermore, TFCC lesions are best identified on MRI exams [18]. By the use of intravenous contrast agents, additional information on vitality and inflammation can be obtained. The standard examination of the wrist should include T1-weighted axial and coronal images as well as T2weighted or STIR sequences in either axial or coronal
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Fig. 9. Biker, 31 year-old, with a bone bruise of the scaphoid. In MR imaging, the distal scaphoid shows a decreased signal intensity in the T1-weighted spin-echo sequence (a), in the T2-weighted sequence the signal is increased (b). Conventional radiographs were normal. The clinical symptoms vanished within 2 weeks without any surgical intervention.
orientation. A slice thickness of 3 mm or less in the axial and 1–2 mm in the coronal planes is preferred. Thicker slices might be less diagnostic and less accurate in depicting the underlying pathology [17,18]. Based on the patient’s history and clinical exam, additional studies might include sagittal or oblique planes. Metacarpus and fingers are preferably scanned using 2 mm thick sagittal and 3 mm thick axial slices. Application of contrast media is usually not required in acute traumatic conditions. Instead, it is necessary for long term control of vitality, e.g. after scaphoid fractures, and for depicting reparative or proliferative post traumatic changes, e.g. in the triangular fibrocartilage complex, or reactive or inflammatory synovial proliferation and enhancement.
3. Osseous lesions Most sports related fractures occur in the scaphoid and triquetral bones, whereas other carpal bones are rarely involved in sports injuries. The imaging impact towards osseous lesions is multiple: first aim is to detect both fractures and occult osseous lesions; accompanying soft tissue lesions, particularly of ligaments, have to be identified; long term control of fracture healing or diagnosis of prevailing pseudarthrosis is another important topic of radiologic imaging.
3.1. Fractures Simple fractures are generally revealed by plain film radiography in standard projections and with clinical correlation (Figs. 1–3). In cases with strong clinical suspicion of a fracture but unequivocal radiographic findings additional projections such as oblique views or scaphoid views may be performed to confirm the diagnosis (Fig. 3). Computed tomography is well suited to evaluate fractures not clearly evident on plain films unless the fracture line is in the plane of section (Fig. 6) [7,19].
3.2. Occult fractures and bone contusions Occult fractures are easily demonstrated on MRI exams by a line of alterated signal intensity through the bony cortex and/or marrow of the respective bone. In many instances, T1-weighted sequences already display a fracture line with decreased signal intensity (SI) compared with fatty marrow and high SI compared with cortical bone. However, fat suppressed sequences, such as STIR, reveal highest sensitivity in the detection of high SI traumatic bone marrow edema accompanying acute fractures or bone contusion (Fig. 9) [15,16,20,21].
3.3. Posttraumatic osteonecrosis The main reasons for the high incidence of posttraumatic avascular necrosis of the scaphoid are frequent
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Fig. 10. Osteonecrosis of the proximal pole of the scaphoid after scaphoid fracture. (a) In T1-weighted MR imaging, the scaphoid is depicted with decreased signal intensity and (b) after intravenous contrast, only the distal pole of the scaphoid enhances. The signal intensity of the proximal part of the scaphoid remains unchanged, indicating insufficient blood supply and avitality.
proximal pole fractures and the lack of sufficient direct blood supply to the proximal part of this bone. Prompt diagnosis and treatment of necrosis is important to minimize complications. Conventional radiographs lag behind the onset of diagnosis and therefore cannot be considered as sensitive. However, MRI is the procedure of choice for the early diagnosis of carpal avascular necrosis, as it is at least as sensitive as bone scintigraphy while being more specific and providing better spatial resolution [22,23]. The most common MR appearance of avascular necrosis of the scaphoid is a decreased SI in the proximal pole on both T1- and T2-weighted sequences. Localized fluid accumulation and marrow edema of the proximal pole may also be observed on T2 weighted images. Based on these findings the sensitivity for scaphoid osteonecrosis is reported to be 87.5%, the specificity 100% [22,23]. Sensitivity may be further increased by intravenous application of gadolinium chelates when the necrotic proximal pole is displayed without enhancement while the viable distal pole shows contrast uptake (Fig. 10).
the joint or tendon sheath, which is sometimes only depicted in tomographic or MRI exams. Posttraumatic bone cysts are depicted in radiographs or CT as a localized loss of structure of the spongy bone with a distinct sclerosis at the border. Quite often, the trauma is not remembered. Subchondral cysts, however, are also often found in degenerative joint disease of the wrist [24].
3.4. Bone cysts and intraosseous ganglia
The biomechanical design of the wrist ensures that a minimum number of ligaments maintain stability throughout a wide range of motion. Many schemes have been developed to explain carpal instabilities. The following is a simplified approach, which reflects a compromise of several authors’ views [27–29]. The main stability and alignment of the wrist is maintained by the palmar ligaments. Dorsal and in-
Bone cysts are more frequently found after trauma or as a result of posttraumatic degenerative joint disease and should not be confused with the channels of nutricial blood vessels in carpal bones. There is no pathologic value to the bone cyst itself. Intraosseous ganglia are cystic lesions characterized by a connecting duct to
3.5. Growth plate lesions In chronically stressed wrists, frequently abnormalities of the growth plate are found in MRI: physeal cartilage extension into the metaphysis seem to represent a healing sign of otherwise occult, horizontal fractures. Chronic repetitive stress on adolescent wrists causes localized growth disturbance of the distal radius, resulting in ulnar plus variance. Permanent sequelae may result even in asymptomatic individuals [25,26].
4. Instabilities and ligamentous injuries
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Fig. 11. Disrupture of the triangular fibrocartilage complex (TFCC) in a 35 year old soccer player. (a) The T1-weighted coronal MR image displays increased signal intensity in the base of the TFCC. (b) After contrast, there is enhancement of the reparative tissue and the rupture of the ulnar ligaments can be seen more obviously.
terosseous ligaments provide additional support. In sports activities, the resultant forces are distributed along the longitudinal axis of the wrist. Most of these axial loading forces project along the long axis of capitate, lunate, and radius. In the neutral ulnar variant, approximately 80% of axial forces are transmitted through the lunate to the radius, while most of the remaining forces are transmitted through the lunate to the ulna. In ulnar or radial deviation, the remaining carpal bones and ligaments balance the axial or longitudinal loading forces. The scaphoid serves as a mobile link between the distal and proximal carpal rows.
4.1.1. Static instability This term refers to changes in carpal alignment. Usually, static instabilities are associated with palmarflexion, dorsiflexion or ulnar migration of the lunate. This disalignment cannot be actively reversed by the patient. Carefully performed routine radiographs display an abnormal carpal configuration (Fig. 4) [2–4].
4.1. Carpal instabilities
4.1.2. Dynamic instability With certain ligaments torn or attenuated, the wrist maintains a normal anatomic position until subjected to an axial loading force. In dynamic instability, the wrist is normally aligned when non-stressed, but collapses into an unstable configuration when loaded with axial force. A fluoroscopic stress exam usually reveals this pathologic condition.
In pathologic condition, the dominant axial loading forces result in wrist shortening. Wrist shortening can be described as a proximal migration of the capitate and occur gradually over time or secondary to severe, acute trauma. Acute fractures and dislocations result from severe and sudden, axial loading forces, for example from a fall on the outstretched hand. Chronic or more subtle acute injuries in particular involve interosseous and volar ligaments. A complex pattern of carpal instabilities results from partial or complete rupture of single or multiple ligaments. Despite the considerable variability of classification systems, a few terms are relatively universally recognized and therefore described.
4.1.3. Midcarpal instabilities Midcarpal instabilities occur between the proximal and the distal carpal rows. The dorsal intercalated segmental instability (DISI) is characterized by dorsal rotation, the volar or palmar intercalated segmental instability (VISI/PISI) by palmar rotation of the lunate. A fall on the outstretched hand is one of the most common accidents in sport leading to carpal instability. The resultant forces may suffice to produce a radius fracture combined with a lunate or perilunate dislocation or a scaphoid fracture (Fig. 4). In the process of healing, quite frequently, residual dorsiflexion of an old distal radius fracture fragment is associated with dynamic DISI without scapholunate dissociation.
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However, even if the force is not sufficient to cause the bony injury mentioned above, tears of the radioscapholunate, dorsal radiocarpal or interosseous scapholunate ligaments can occur. The weakest link between the radius and proximal carpal row is the radioscapholunate ligament (RSL). For this reason, the most common mid-wrist instability, the DISI, often is accompanied by scapho-lunate dissociation. VISI is the more uncommon form of the midcarpal instability. Patients frequently complain of a painful clunk that occurs during sports activities involving pronation and ulnar deviation of the wrist. DISI and VISI configurations can be diagnosed on standard lateral projections of the wrist [2,4]. MRI also constantly shows the radioscapholunate, lunotriquetral, and the interosseous ligaments projecting to the capitate on coronal images with a slice thickness of 1–2 mm [15].
4.1.4. Lateral and medial carpal instabilities This classification is based on the functional concept of three carpal columns. Lateral carpal instability refers to instability between the lateral column, formed by the scaphoid, and the central column, which consists of the lunate-capitatetrapezoid-trapezium row. Scapholunate dissociation, scaphocapitate diastasis, and scaphotrapezoid instabilities are major subsets of this group. As the lateral column controls lunate volarflexion, lateral carpal instability is typically associated with a DISI. Medial carpal instabilities are caused by dissociation of the medial column, which is formed by the triquetum, and the central column. Triquetrolunate and triquetohamate dissociation are the major subsets of this entity. The medial column restrains the dorsal flexion of the lunate. Therefore, medial carpal instabilities typically result in VISI. If standard radiographs are not diagnostic and the nature of the instability is unclear, a dynamic MRI exam is mostly suggestive of the lesion [27]. 4.2. Luxations and subluxations 4.2.1. Scapholunate ad6anced collapse (SLAC) The scapholunate advanced collapse (SLAC) is the most common form of human wrist degenerative arthritis. It is characterized by a rotary subluxation of the scaphoid, in which its proximal articular surface is displaced from its normal elliptic fossa in the radius. The progressive loss of scaphoid cartilage results in progressive scaphoid collapse. Because of the further increase in capitolunate load, the capitate migrates proximally to the scapholunate gap, and the lunate translocates ulnarly. The wrist shortening can cause proximal migration of the transverse carpal ligament and thus may result in carpal tunnel syndrome. SLAC
wrists are easily diagnosed on plain films. In addition, MRI contributes to detection of associated lesions and therapy planning.
4.2.2. Hand Martial sports, basketball and volleyball put extra stress on metacarpus and fingers. Frequently luxations and subluxations of the metacarpals and fingers result. Plain radiographs in two projections depict these lesions very well. For demonstration of ligamental lesions, ultrasound and MRI provide more information. MRI also depicts accompanying lesions, of e.g. bones and tendons, best. 4.3. Triangular fibrocartilage complex (TFCC) The normal TFCC includes the articular disk, the meniscal homologue, and the stabilizing ligaments of this functional unit: the palmar and dorsal radio-ulnar ligaments, the ulnar collateral ligament, the sheath of the ulnar extensor, and the ulno-lunate and-triquetral ligaments [30–32]. The TFCC has three major functions [31]: (a) it bears up to 20% of the axial load of the wrist; (b) it stabilizes the distal radio-ulnar joint; (c) it firms the ulnocarpal joint. For TFCC evaluation, arthrography has been considered a standard technique (Fig. 7b). No obvious advantage of post-arthrographic CT over conventional arthography has been found so far [4]. By using thin slice techniques a suitable spatial resolution has been achieved in standard MRI exams [18]. MR has emerged as a precise, non-invasive technique with an accuracy of 95%, using open surgery or arthroscopy as a gold standard (Fig. 11) [4,32]. Thus, therapy can be planned more easily without preceding invasive diagnostic measures [3,30,32]. Considering the lower cost of the three compartment arthrogram in comparison to MRI in the aspect of additional information gained by an MRI exam, no clear decision in favor of arthrography or MRI can be made [8]. In MRI, the normal articular disc appears as a thick band of low signal intensity. In the sagittal planes, the disc appears biconcave, in the coronal triangular. The peripheral margins appear thicker and stronger than the central zone [30,31]. The meniscal homologue represents a region of ill defined, irregular, more or less dense fibrous tissue. Both the meniscal homologue and the ulnar extensor tendon subsheath appear inconstant on MRI studies. The collateral ulnotriquetral and ulnolunate ligaments can constantly be identified in sagittal thin sections. Degenerative changes of the articular disc appear as signal alterations, mostly starting from the lateral aspect of the TFCC. Tears of the TFCC are visualized in MRI as discontinuities and fragmentation of the low signal intensity band representing the articu-
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Fig. 12. Longitudinal T1-weighted MR image of D V. Increased signal intensity and thickening of the extensor tendon indicates a partial tear. Note that there is no retraction of the proximal and distal part of the tendon.
lar disk and the contour of the disk becomes irregular in shape. The overall sensitivity of MRI in comparison to arthroscopy is excellent (1.0), also the specificity (0.93) [30,32]. However, quite often in the asymptomatic adult, signal alterations in the more central part of the TFCC make the differentiation of a recent traumatic lesion from a traumatic lesion more difficult. If the TFCC was damaged in recent trauma, the region enhances after intravenous contrast. This enhancement represents reparative tissue, providing another clue on the differential of abnormal signal intensity. Intravenous contrast is therefore recommended in unclear cases (Fig. 10).
surgical intervention is advocated to allow healing, otherwise immobilization may suffice [37]. Clinical exam and conventional radiographs in additional stress views allow the diagnosis of UCL rupture, however, the displacement is not depicted. Sonographic exams allow a reliable diagnosis of displacement in 86% [37]. In a preliminary MR imaging study, UCL displacement could be depicted with a sensitivity of 100% and a specificity of 94% [38]. Therefore, both US and MRI may add important information particularly in patients with ambiguous clinical signs, for whom surgical treatment should be discussed.
5. Tendinous lesions
4.4. Ulnar collateral ligament of the thumb Traumatic abduction of the thumb is most frequently seen in skiers and gamekeepers. The resulting lesion of the ulnar collateral ligament (UCL) in the metacarpophalangeal joint is therefore often referred to as skier’s or gamekeeper’s thumb and classified according to Stener [33]. The anatomic position of the UCL is underneath the adductor/extensor aponeurosis of the thumb, where it extends from the dorso-ulnar aspect of the metacarpal to the volar-ulnar side of the base of the proximal phalanx. Most of the time, the ligamentous rupture is found in the distal, phalangeal portion. The proximal part retracts, and often there is interposition of the aponeurosis between the proximal part of the UCL and its insertion at the proximal phalanx [34 – 37]. In situation of displacement of the proximal part of the UCL,
Sports related tendinous lesions of the hand and wrist may affect the flexor or the extensor group [1,39].
5.1. Tendon rupture Complete tendon ruptures are rare and usually occur with acute hyperextension or hyperflexion trauma or as a result of maximum mechanical stress. Frequently, alterations of the respective tendon, such as myxoid degeneration or tendinitis, are found as predisposing factors at the rupture site. While the majority of complete tendon ruptures can be diagnosed clinically, the exact location and extent of a tear may be difficult to determine and, therefore, requires preoperative imaging assessment [39]. Partial tendon tears are related to acute mechanical stress or chronic trauma and are more common than
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Fig. 13. Tenovaginitis stenosans de Quervain in a 38 year-old tennis player. The tendon sheaths of the extensor pollicis brevis and of the abductor pollicis longus (arrows) are thickened (a) and enhance after contrast (b).
complete ruptures. As the clinical diagnosis may be difficult, imaging techniques are needed for further evaluation and the establishment of diagnosis. Adhesions and scar tissue formation around a repaired tendon are frequent postoperative complications that lead to functional impairment. Differentiation between re-rupture and scar formation may also be difficult on clinical grounds. Standard radiographs are important to prove or rule out tendon avulsion. Ultrasound is useful in identifying the site of complete tendon ruptures (Fig. 8), especially when the defect is filled by an organizing blood clot and creates difficulties in clinical diagnosis [40]. Beside an exact location, the distance between the two parts of the torn tendon can be measured by ultrasound and may help to determine the type of treatment to be adapted. Acute partial ruptures may variously present as a defect of the tendon contour, a localized thickening of the tendon and/or intra- or peritendinous hematoma. Chronic partial tears present as a localized inhomogeneous, hypoechoic thickening of the tendon. MRI excellently depicts the pathologic tendinous anatomy of the wrist and hand while simultaneously displaying bony and other soft tissue structures [41]. Complete tendon ruptures are seen as a gap in the continuity of the low SI tendon. Depending on the material which fills the gap (fluid, hematoma, or repair tissue) its SI in T1- and T2-weighted images may vary but lies always considerably above that of normal tendons. Incomplete ruptures (Fig. 12) or chronic tears are depicted by MRI as irregular thinning or thickening of the tendon, sometimes with linear areas of high SI on long TR/TE images, within the substance of the tendon [42]. Post surgical scarring can be accurately differentiated from tendon re-rupture by MRI as in
these cases it shows irregularity of the tendon contour and low SI scar tissue. Computed tomography may also depict complete tears with a gap of the tendon and incomplete tears with focal irregularities, however, it is considered less sensitive and specific than MRI.
5.2. Tendinitis, tenosyno6itis and other o6eruse syndromes Tendinitis and tenosynovitis are common findings in overuse syndromes of athletes participating in racquet sports, rowing and weight lifting [43–45]. A common site of tenosynovitis in racquet sports is the first extensor compartment involving the abductor pollicis longus and extensor pollicis brevis tendons and sheaths at the level of the radial styloid. This condition is known as de Quervain’s tenosynovitis (Fig. 13). Typical clinical findings are pain and swelling in the anatomic snuff box (tabatie`re), in late stages associated with entrapment or limited extension of the thumb. Other overuse syndromes leading to tendinitis and tenosynovitis involve the extensor carpi radialis longus and brevis tendons (frequently associated with carpal boss), the extensor carpi ulnaris tendon in the region of the fibroosseous tunnel, and most frequently the flexor carpi ulnaris and flexor carpi radialis tendons. The intersection syndrome is characterized by irritation of a bursa located at the intersection of the extensor carpi radialis longus and brevis and the abductor pollicis longus. Clinical symptoms are pain, weak grasp, and crepitation (squeaker’s wrist). Radiographs are performed to rule out avulsion injury or calcific tendinitis. US may be useful in depicting pathology of tendons or tendon sheaths, particularly the fluid filled tendon sheaths in acute tenosynovitis.
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Fig. 16. Hematoma in the pronator quadratus muscle in a 17 year-old inline skater who didn’t wear his wrist protection gear. There is increased signal intensity in the T2-weighted turbo-spin echo sequence.
Fig. 14. MR imaging of a pulley injury in a sport climber. (a) Schematic drawing of the annular (A1–A5) and cruciate (C1 – C3) pulleys of the finger. (b) T1-weighted longitudinal image of a normal ring finger. The black flexor tendon is closely related to the palmar surface of the proximal phalanx. (c) Proton-density weighted MR image of the ring finger in a climber with a A2 pulley injury. Note the increased distance between the tendons and bone (arrowheads) and a small ganglion cyst extending from the flexor tendon sheath (arrows). (d) T2-weighted image, same as in (c). High signal intensity between flexor tendons and bone (arrow heads) indicates edema and hemorrhage as a result of A2 pulley tear. High signal intensity of the ganglion cyst.
However, the distinction between partial chronic rupture and chronic tendinitis is difficult by sonographic criteria alone. Therefore, MRI should be employed for a more detailed assessment. Acute tenosynovitis is displayed with high SI of fluid on T2-weighted or STIR
Fig. 15. Axial T2-weighted MR image of the carpal tunnel: transient edema of the median nerve (arrow) in a 17 year-old inline skater. Hyposensitivity of the finger tips on clinical exam.
images distending the synovial sheaths and, if associated with tendinitis, with swelling and high SI within the tendon substance. After application of Gadolinium contrast agents the tendon sheath may enhance due to hyperaemia of the tenosynovium. Chronic tenosynovitis is depicted as tendon and synovial sheath thickening with or without fluid in the sheath and peritendinous edema. Contrast enhancement may be mild to very intense, depending on the degree of inflammatory or proliferative reactions. In late stages, fibrotic changes without significant contrast uptake may be predominant. Thus, contrast enhanced MRI allows for determination of the disease activity [46].
5.3. Pulley injuries The commonest acute hand injury in competition rock climbers affects the A2 pulley of the flexor tendon sheath of the ring or middle finger [45,47,48]; other pulleys are less frequently involved [49]. The annular pulleys (A1–A5) are strong, ring-like fibrous structures which arise from and inseparably merge with the periosteum of the phalanges and strenghten the flexor tendon sheaths [45,47,48]. The rupture most often occurs while climbers are holding or pulling up on a small hold with one or two fingers (usually the third and fourth finger). Clinical findings are swelling and increased ‘bow-stringing’ of the flexor tendon on resisted flexion. In high resolution MRI the normal flexor tendons are displayed with low SI in very close relation to the phalangeal bones (Fig. 14). As the pulleys are part of the flexor tendon sheath, they cannot generally be identified as separate structures. However, increased distance between the flexor tendon and the phalanx together with increased SI between the two due to edema and hemorrhage can be considered as sensitive
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and reliable indicators for acute annular pulley rupture (Fig. 14).
6. Soft tissue lesions
6.1. Post-traumatic ner6e impairment Nerve impairment may be found in acute or chronic injury or overuse syndromes [50,51]. The most common site of nerve impairment in the hand and wrist region is the carpal tunnel, whereas the ulnar tunnel (Guyon’s canal) is less often involved. In acute injury, nerve compression by displaced fracture fragments, hematoma or soft tissue edema may result in neurologic symptoms typical for the nerve involved. Also, chronic injuries or overuse reactions associated with thickening of the flexor retinaculum, flexor tendons and tendon sheaths, or even with hypertrophy and more distal extension of the flexor muscles (e.g. in rock climbers) may lead to transient sensory or motoric deficits. While CT has proven to be the method of choice in the work-up of osseous carpal stenosis [50], US and MRI are most valuable imaging modalities for detecting alterations of the median nerve and underlying soft tissue alterations [51 – 53] (Fig. 15). The most frequent finding of carpal tunnel syndrome (CTS) are edema and deformation of the median nerve due to mechanical compression. Other soft tissue findings may include tenosynovitis, tendinitis and interstitial edema.
6.2. Muscular lesions Although muscular trauma frequently occurs in sports injuries, only very little has been reported on muscular lesions of the hand and wrist region. Most sports-related muscle injuries are located in the thigh and lower leg and comprise of a variety of different lesions ranging from minor strains to severe tears including necrosis and hematoma [54,55]. However, even if muscular injuries of the hand appear relatively rare, the resulting lesions can be assumed to be very similar to other locations. Radiologic techniques which allow for detection of muscle injuries include US [10,14], computed tomography [54], and MRI [55 – 58]. The US appearance of traumatic muscle lesions depends on their extent. Simple strains or partial tears cannot be accurately detected, but a hypo- or anechoic hematoma can be demonstrated as the sole evidence of an incomplete muscle tear. In extreme cases with complete muscle rupture, two muscle fragments are separated by a gap of hematoma and edema. Partial chronic muscle tears lead to fibrosis and scar with ill-defined hyperechoic regions. CT is not a very sensitive imaging modality for the proof of muscle injuries, however, severe pathologic
changes such as muscle necrosis and hematoma may be depicted [54]. In contrast, MRI has been shown to be a very sensitive and specific technique for detection and differentiation of traumatic muscular lesions. Strains can be identified by a diffuse hazy hyperintensity on T2weighted and STIR images, while partial tears usually demonstrate an additional focal area of relative hyperintensity. Associated subacute hemorrhage may be displayed with increased SI in T1-, T2-weighted and STIR images, reflecting the presence of methemoglobin. Discontinuity of the muscle and the presence of extensive hematoma and interstitial edema are reliable indicators for complete muscle tears (Fig. 16).
7. Conclusion Radiologic imaging procedures are indispensible for the depiction, localization and accurate diagnosis of most sports-related hand and wrist injuries. Conventional radiographs form the basis of hand and wrist imaging in providing important information on fractures, dislocations and some instabilities. CT is of value in the evaluation of complex and hidden carpal fractures, (sub-)luxations and malrotations and of major soft tissue lesions. Arthrography is a valuable method for the evaluation of carpal interosseous ligaments, joint capsules and the TFCC. Ultrasound displays most soft tissue lesions, such as tendon ruptures or hematoma. As no other modality, MRI allows direct visualization of both osseous and soft-tissue components of the hand and wrist. Subtle abnormalities, such as occult fractures or bone contusion, early stages of osteonecrosis, as well as injuries of tendons, ligaments and muscles may be detected very accurately, thus permitting early diagnosis.
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