MDCT arthrography for detecting traumatic scapholunate dissociation associated with intra-articular radius fractures

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1 MDCT arthrography for detecting traumatic scapholunate dissociation associated with intra-articular radius fractures Poster No.: B-757 Congress: ECR 2010 Type: Scientific Paper Topic: Musculoskeletal Authors: R. Schmitt, S. Fodor, S. Froehner, K.-J. Prommersberger, K.-H. Kalb, G. Christopoulos; Bad Neustadt an der Saale/DE Keywords: scapholunate ligament, scapholunate dissociation, combined radius-wrist injury DOI: /ecr2010/B-757 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 19

2 Purpose The scapholunate interosseous ligament (SLIL) is the most important stabilizer of the wrist [1]. The SLIL, which bends like a horseshoe in sagittal extension between the scaphoid and lunate, is built of three segments with different anatomy and strength (figure 1). The thick and short dorsal SLIL segment ensures nearly the entire ligament stability, whereas the volar SLIL segment extends transverse-obliquely and has only modulatory function of the scapholunate movement [2,3]. The middle SLIL segment is a thin membrane without any stabilizing function. Visualization of the SLIL and discrimination of its segments is best done with the use of MR arthrography and CT arthrography [4-6] as shown in the normal case of figure 2. Intra-articular fractures of the distal radius are often associated with disruptures of the scapholunate interosseous ligament leading to scapholunate dissociation (SLD). Pathoanatomic basis is the continuous force transmission from the radius to the wrist [7]. When the scaphoid fossa or the lunate fossa of the distal radius is fractured, the force vector applied at the injury is crossing the scapholunate compartiment, thereby damaging the SLIL (figure 3). However, combined forearm-wrist lesions are significantly more frequent in daily practice than really diagnosed by means of clinical and radiologic signs [8,9]. There are two reasons for misinterpretion of the wrist: Firstly, scapholunate instability is a dynamic pattern in most cases, therefore being "occult" in standard X-ray views [1]. Secondly, displaced fractures of the radius may take off the reader's attention from accompanying wrist pathology. In literature, the true incidence of traumatic SLD has been reported in ranges between 11 and 54% [8,9]. Thus, the aim of this study was to assess the true incidence of SLD in the presence of intra-articular radius fractures and to determine the diagnostic accuracy of MDCT arthrography. Images for this section: Page 2 of 19

3 Fig. 1: Schematic anatomy of the scapholunate interosseous ligament (SLIL). The SLIL insertions are depicted in yellow on 3D-CT images of the scaphoid and the mirror-inverted lunate. In sagittal cross-section, the SLIL is U-shaped and composed of three parts: The strong dorsal segment (dsll) providing ligament stability, the membranous middle segment, and the thin volar segment (vsll). On the volar site, the radioscapholunate ligament (RSLL, Testut's ligament) is also depicted. Page 3 of 19

4 Fig. 2: Normal scapholunate interosseous ligament as seen in CT arthrography. Coronal slices were reconstructed from an axial, post-arthrographic 3D CT dataset using the MPR mode. The dorsal segment (red arrow), the middle segment (yellow arrow), and the volar segment can easily be delimited from the intra-articular contrast agent. Page 4 of 19

5 Fig. 3: Schematic illustration of the force transmission at the distal forearm and wrist as being efficient at the injury moment. The red double-arrow is indicating the force vector which runs from the distal radius end through the wrist to the metacarpus. Often the scapholunate compartment is the preferred place where the traumatic force load is acting at the wrist. Page 5 of 19

6 Methods and Materials In a prospective study, a total of 182 patients suffering from acute intra-articular fractures of the distal end of the radius underwent MDCT arthrography. The study group consisted of 111 women and 71 men (mean age 49 years, range from 31 to 78 years) which all were injured within the last 5 days before arthrographic MDCT imaging was performed. In first step, the patients underwent three-compartment arthrography. The midcarpal, the distal radioulnar, and the radiocarpal joint compartments were filled in this order with iodinated contrast material (200mg/ml) under fluoroscopic guidance (figure 1). The number of injections was reduced in case of intercompartmental contrast communication. Immediately after arthrography, transaxial CT images were acquired using a 16-row CT scanner (figure 2). Scan parameters: 120mV, 100mAs, FoV 80mm, slice thickness 0.6mm, pitch factor 1.3, reconstruction increment 0.4 mm. Multiplanar reconstructed (MPR) images were calculated in the coronal and sagittal planes from the volumetric data sets. The post-arthrographic CT images were interpreted by three MSK experienced radiologists with respect to the extent of the distal radius fractures (classifications of Frykman [10] and Fernandez [11]), and the presence of intra-articular soft-tissue lesions. Joint evaluation included disruptures of the scapholunate (SLIL) and lunotriquetral (LTIL) ligaments, lesions of the triangular fibro-cartilage complex (TFCC), and lesions of the articular cartilage. Both the SLIL and LTIL were subdivided into three ligament segments (dorsal, middle, and volar) according to Sokolow [3]. Based on MDCT arthrography findings, surgical treatment was planned (closed reduction versus open reduction without or with SLIL repair). The conditions of the injured SLIL were assessed in 45 surgically treated patients using either volar arthroscopic or direct surgical approaches. Images for this section: Page 6 of 19

7 Fig. 1: Three-compartment arthrography of the wrist. a) Fluoroscopic injection of the contrast material under sterile conditions. b) Midcarpal arthrography. c) Arthrography of the distal radioulnar joint. d) Radiocarpal arthrography. Page 7 of 19

8 Fig. 2: Post-arthrographic CT scanning of the wrist. a) Transaxial image acquisition with the patient standing beside the CT gantry and the hand and forearm in prone position. b) Transaxial source image at the height of the distal radioulnar joint. c) Coronal reformatted image. d) Sagittal reformatted image. Page 8 of 19

9 Results All wrist arthrograms were tolerated by the patients without any adverse effects, i.e. no allergic reactions and articular infections were noted. In 117 patients (64%), the SLIL was seen unaltered in MDCT arthrography (figure 1). The continent dorsal (dsll) and volar (vsll) segments clearly indicated stability of the scapholunate compartment in these individuals. Small pin-hole lesions in the middle SLIL segment were judged as degenerative without any ligament instability in 24 cases. In 65 wrists (36%), traumatic SLIL lesions of the following segments were found: Complete SLIL tears involving all three ligament segments were detected in 21 cases (12%). A characteristic trauma case with other accompanying articular lesions is depicted in figure 2. Partial SLIL tears were found in 44 cases (24%). In this patient subgroup, the stabilizing dorsal ligament portion (dslil) was ruptured in 27 cases (figure 3), whereas the volar ligament portion (vsll) was solely injured in the remaining 17 cases (9%). In summary, the stabilizing dslil was injured in 48 of the 182 distal radius fractures (26%) resulting in carpal instability additionally to the intra-articular radius fractures. 45 of the 48 patients with injured SLILs underwent arthroscopic or surgical inspection. In 2 cases, the dsll was found intact at surgery, while in 43 cases the dslil tears were confirmed, resulting in a positive predictive value (ppv) of 96% for MDCT arthrographic imaging. The remaining 134 patients, who did not reveal signs of a dsll lesion in MDCT arthrography, were not reevaluated with arthroscopy or surgery. Additional intra-articular soft-tissue injuries were found in MDCT arthrography: Lesions of the lunotriquetral ligament (LTIL) were depicted in 19 wrists (10%) (figure 2). Lesions of the triangular fibro-cartilage complex (TFCC) were present in 107 cases (figures 3 and 4). Only in 34 of the 107 TFCC lesions (32%), differentiation of traumatic lesions from degenerative TFCC defects was possible when judging the sharp margins of the altered discus as being of acute traumatic nature. Articular cartilage defects were seen in all cases at the intra-articular fracture sites. The degree of chondral pathology varied from small fissures of the cartilage to focal lesions (figure 4) up to territorial chondral defects (figure 3). Page 9 of 19

10 Images for this section: Fig. 1: Unaltered SLIL in the presence of a distal intra-articular radius fracture. a) Radiographic views are showing a Colles' hyperextension fracture (type Frykman VII, Fernandez II). b) Normal midcarpal arthrogram. c) In transaxial MDCT arthrography normal extension of the dorsal (red arrow) and volar (green arrow) SLIL segments. d) f) Coronal MPRs are displaying a normal dorsal (red arrow), middle (yellow arrow), and volar (green arrow) SLIL segments. Page 10 of 19

11 Fig. 2: Minimally displaced radius fracture combined with an advanced intra-articular ligament damage. a) Impacted radial lunate fossa in radiographic views. b) Postoperative views after ligament repair and transitional carpal splinting. c) Midcarpal arthrogram with intercompartimental communications across the scapholunate (black arrow) and lunotriquetral (blue arrow) pathways. d) - f) Coronal MPRs are displaying the completely ruptured SLIL at the dorsal segment (red arrow), middle segment (yellow arrow), and volar segment (green arrow). Additionally, there are a partial LTIL tear (blue arrows), and a broad central TFC defect adjacent to a chondral lesion of the lunate (small arrows). Fig. 3: Partial rupture of the SLIL associated with a distal intra-articular radius fracture. a) Radiographic views are depicting a moderately impacted Colles' hyperextension fracture (type Frykman VII, Fernandez IIa). b) In transaxial MDCT arthrography discontinent dorsal SLIL segment (red arrow) and unaffected volar SLIL segment (green arrow). c) In sagittal MPR the destroyed radial joint surface and the ruptured dorsal SLIL segment (red arrow) are evident. d) - f) Coronal MPRs are showing disruption of the dorsal (red arrow) and middle (yellow arrow) SLIL segments, while the volar SLIL segment (green arrow) is intact. Broad central lesion of the TFC (small arrows). Page 11 of 19

12 Fig. 4: Only minimally displaced radius fracture (type Frykman III, Fernandez II) presented in postarthrographic coronal MPR images. a) - c) The SLIL, the LTIL and the TFC are all not injured. D) There is a small contrast-filled defect within articular cartilage of the radial lunate fossa directly at the intra-articular insertion site of the fracture cleft (small arrow). Page 12 of 19

13 Conclusion These are the conclusions of our study: Traumatic scapholunate instability is associated in 26% of all intra-articular fractures of the distal radius end. Therefore we recommend to rule out always the possibility of a ruptured scapholunate ligament in the presence of an intra-articular fracture course. When comparing with arthroscopy as the standard of reference [12], MDCT arthrography is highly accurate in detecting SLIL injuries. By applying MDCT arthrography, the different SLIL segments can exactly be depicted, and the continuity resp. discontinuity of the stabilizing dorsal segment can be evaluated. Indication for CT scanning is generally given in intra-articular radius fractures to provide three-dimensional information for detailed surgical planning. Combined CT arthrography is semi-invasive, easy to perform at the wrist, and justified with respect to the diagnostic benefit in the evaluation of the carpal ligaments. Finally, the fracture-associated force loading at the scapholunate compartment is biomechanically demonstrated in figure 10, where the intra-articular course of the radius fracture is directly neighbored to the widened scapholunate cleft. Images for this section: Fig. 1: Biomechanical synopsis of the combined radius-slil injury. The close neighborhood of the intra-articular radius fracture on the one side and the widened Page 13 of 19

14 scapholunate compartment on the other side is clearly depicted in this volumetric CT data set. a) Coronal MPR view. b) Volume-rendered display after electronic exarticulation of the carpus. c) Asymmetrically widened SL compartment adjacent to the radial fracture cleft as seen from a distal view point. Page 14 of 19

15 References [ 1 ] Schmitt R, Froehner S, Coblenz G, Christopoulos G. Carpal instability. Eur Radiol 2006;16: [ 2 ] Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg Am 1996;21: [ 3 ] Sokolow C, Saffar P. Anatomy and histology of the scapholunate ligament. Hand Clin 2001;17:77-81 [ 4 ] Blum A, Bresler F, Voche P, Merle M, Regent D. CT-arthrography of the wrist. In: Gilula and Yin (eds). Imaging of the Wrist and Hand. Saunders. Philadelphia 1996: [ 5 ] Schmid MR, Schertler T, Pfirrmann CW, Saupe N, Manestar M, Wildermuth S, Weishaupt D. Interosseous ligament tears of the wrist: comparison of multi-detector row CT arthrography and MR imaging. Radiology 2005;237: [ 6 ] Theumann N, Favarger N, Schnyder P, Meuli R. Wrist ligament injuries: Value of post-arthrography computed tomography. Skeletal Radiol 2001;30:88-93 [ 7 ] Mayfield JK, Johnson RP, Kilcoyne RK (1980) Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am 1980;5: [ 8 ] Forward DP, Lindau TR, Melsom DS. Intercarpal ligament injuries associated with fractures of the distal part of the radius. J Bone Boint Surg Am 2007;89: [ 9 ] Schneiders W, Amlang M, Rammelt S, Zwipp H. Frequency of acute and chronic scapholunate dissociation in distal radius fractures. Unfallchirurg 2005;108: [ 10 ] Frykman G. Fracture of the distal radius including sequelae-shoulder-hand-finger symdrom, disturbance of the distal radio-ulnar joint and impairment of nerve function. Acta Orthop Scand 1967;108 (Suppl):30-31 [ 11 ] Fernandez DL, Jupiter JB. Fractures of the distal radius. A particle approach to management. New York. Springer 1996 [ 12 ] Hohendorff B, Eck M, Mühldorfer M, Foder S, Schmitt R, Prommersberger KJ. Palmar wrist arthroscopy for evaluation of concomitant carpal lesions in operative treatment of distal intraarticular radius fractures. Handchir Mikrochir Plast Chir 2009;41: Page 15 of 19

16 Personal Information Rainer R. Schmitt, MD Associate Professor of Radiology Department of Diagnostic and Interventional Radiology Heart, Hand and Vascular Center Bad Neustadt Salzburger Leite 1 D Bad Neustadt an der Saale Fon: Fax: Mail: schmitt.radiologie@herzchirurgie.de schmitt@radiodiagnostics.de Images for this section: Page 16 of 19

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18 Fig. 1: Rainer Schmitt, MD Associate Professor of Radiology Page 18 of 19

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