Imaging and Treatment of Scaphoid Fractures and Their Complications

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Mihra S. Taljanovic, M.D., M.Sc., F.A.C.R. 1 Apostolos Karantanas, M.D., Ph.D. 2, 3 James F. Grifﬁth, M.D. 4 Gregory L. DeSilva, M.D. 5 Joshua D. Rieke, M.D. 1 Joseph E. Sheppard, M.D. 5

1 Department of Medical Imaging, The University of Arizona Health Address for correspondence and reprint requests Mihra S. Taljanovic, Network, Tucson, Arizona. M.D., M.Sc., Department of Medical Imaging, The University of Arizona 2 Department of Radiology, University of Crete, Heraklion, Greece. Health Network, 1501 N. Campbell Ave., Tucson, AZ 85724-5067 3 Department of Medical Imaging, University Hospital, Heraklion, (e-mail: [email protected]). Greece. 4 Department of Imaging and Interventional Radiology, Prince of Wales Hospital, Shatin, New Territories, Hong Kong. 5 Department of Orthopaedic Surgery, The University of Arizona Health Network, Tucson, Arizona.

Semin Musculoskelet Radiol 2012;16:159–174.

Abstract The scaphoid is the most commonly fractured carpal bone, with frequent complications that are predisposed by its anatomical location, anatomical configuration (shape and length), and vascular supply. The most common mechanism of injury is a fall onto an outstretched hand. Imaging plays a significant role in the initial evaluation and treatment of scaphoid fractures and their complications. Radiography should be the first imaging modality in the initial evaluation and follow-up of scaphoid fractures. Computed tomography with its superb spatial resolution enables better visualization and characterization of the fracture line, and the amount of displacement and angulation of the fracture fragments. Using the metal reduction artifact with computed tomography allows good follow-up of scaphoid fractures despite surgical hardware. Magnetic Keywords resonance imaging without contrast is the imaging modality of choice for depiction ► scaphoid of radiographically occult scaphoid fracture, bone contusion, and associated soft tissue ► fracture injury; contrast-enhanced imaging aids assessment of scaphoid fracture nonunion, ► nonunion osteonecrosis, fracture healing after bone grafting, and revitalization of the necrotic ► osteonecrosis bone after bone grafting. Proper identification and classification of scaphoid fracture and ► radiography its complications is necessary for appropriate treatment. This article describes the ► fi

MRI normal anatomy, mechanism of injury, and classi cation of stable and unstable fractures, Downloaded by: University of Colorado Denver. Copyrighted material. ► CT together with the imaging and treatment algorithm of scaphoid fractures and their ► treatment complications with an emphasis on magnetic resonance imaging.

The scaphoid is the most frequently injured carpal bone. Often misdiagnosed as a simple wrist sprain, scaphoid frac- Scaphoid fractures account for 60 to 70% of all carpal fractures are prone to complication.3 Early diagnosis of scaphoid tures1 (►Figs. 1 and 2). Young active adults are most com- fractures (►Fig. 3) is of great importance to minimize these monly affected with a male predominance.1,2 Patients with potential complications such as nonunion (►Figs. 4–7), os- scaphoid fractures most often present with wrist pain and teonecrosis (►Figs. 8 and 9), carpal instability, and osteoar- with tenderness and fullness in the anatomical snuffbox. thritis (►Fig. 10).4

Issue Theme Hand and Wrist Imaging; Copyright © 2012 by Thieme Medical DOI http://dx.doi.org/ Guest Editor, Andrea S. Klauser, M.D. Publishers, Inc., 333 Seventh Avenue, 10.1055/s-0032-1311767. New York, NY 10001, USA. ISSN 1089-7860. Tel: +1(212) 584-4662. 160 Scaphoid Fractures Taljanovic et al.

Figure 1 (A–D) An 18-year-old male patient with an acute scaphoid waist fracture. (A) Posteroanterior (PA), (B) PA oblique, (C) lateral, and (D) PA ulnar deviation radiographs of the left wrist show a minimally displaced scaphoid waist fracture (arrows) that is best seen in the PA ulnar deviation projection.

Normal Anatomy and Mechanism of Injury the lunate and capitate, and distally with the trapezium and trapezoid bones. The normal anatomy of the scaphoid bone The scaphoid is the most radially positioned bone of the includes the distal pole, the volar tubercle located at the distal proximal carpal row, and it articulates proximally with the pole immediately proximal to the trapezium, the waist, and Downloaded by: University of Colorado Denver. Copyrighted material. radial styloid at the scaphoid fossa, at the ulnar side with the proximal pole. All of these structures may be identiﬁed on radiographs.5 The scaphoid receives its blood supply from the branches of the radial artery in a retrograde fashion (►Fig. 11).6 The proximal pole of the scaphoid is ﬁxed in place volarly by the strong extrinsic radioscaphocapitate and long radiolunate ligaments and the intrinsic capsular palmar scaphotriquetral ligament. The intrinsic interosseous ligaments (scapholunate, scaphocapitate, and scaphotrapeziotra- pezoid) connect the scaphoid to the neighboring bones. At the dorsal side of the carpus, the intrinsic capsular dorsal inter- carpal ligament attaches via its proximal band to the scaphoid bone waist. The less important radial collateral ligament extends from the radial styloid to the scaphoid waist.7,8 Figure 2 (A, B) Comminuted right scaphoid distal pole fracture in a Most carpal bone fractures occur along the zone of vul- 20-year-old male patient who was treated conservatively with a spica nerability (►Fig. 12), which follows the direction of the major cast. (A) Posteroanterior (PA) ulnar deviation radiograph of the right volar wrist ligaments starting at the radial styloid, traversing wrist shows a comminuted fracture of the distal scaphoid pole (arrow). the waist and proximal pole of the scaphoid and the body of (B) PA radiograph of the right wrist obtained 8 weeks later shows that the fracture is healed (arrow). Note generalized osteopenia secondary the capitate before turning ulnarly to include the base of the 9 to disuse. hamate and the ulnar styloid. The mechanism of injury is

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Figure 3 (A–D) A 16-year-old male patient with a nondisplaced fracture of the proximal pole of the right scaphoid treated with open reduction and internal fixation (ORIF). (A) Posteroanterior (PA) radiograph of the right wrist shows a subtle fracture of the proximal scaphoid pole (arrow). The fracture line is better seen on (B) the coronal T1-weighted and (C) short tau inversion recovery magnetic resonance images (arrows). Note bone marrow edema of intermediate signal intensity in (B) and high signal intensity in (C) involving the near entire scaphoid bone. (D) PA radiograph of the radial side of the right wrist obtained 8 weeks after ORIF shows a dorsally placed variable pitch cannulated fixation screw transfixingahealedscaphoidfracture.

most often due to hyperextension of the wrist, but it can also scaphoid injury.1,5 Perilunate fracture dislocations are rela-

result from a pure compressive force. A fall on an outstretched tively uncommon but may be associated with scaphoid Downloaded by: University of Colorado Denver. Copyrighted material. hand causes palmar tensile and dorsal compressive force on fracture (►Fig. 13) and occur as a result of high-energy the scaphoid, and it is the most common mechanism of trauma10 with notable disruption of the carpal arcs.11 The scaphoid is a critical link in the biomechanics of the carpus and participates in the movement of both proximal and distal rows. Because of its offset articular surfaces both proximally and distally, the scaphoid has a natural tendency to palmar-ﬂex with longitudinal loading. Therefore, scaphoid extension places progressively increasing tension on the palmar cortex of its curved waist. Excessive extension or ulnar deviation of the wrist, associated with excessive loading, predisposes the scaphoid to fracture. This is especially true if the strong ligaments attached to the scaphoid retain their integrity. When a fracture occurs proximal to the scaphoid waist, it is predisposed to displacement because of the opposing forces acting on the proximal and distal fragments as well as the distribution of ligament attach- Figure 4 Nonunited displaced scaphoid fracture in a 30-year-old male ments. The distal entry point of nutrient vessels and a patient. Posteroanterior radiograph of the left wrist shows a displaced nonunited scaphoid fracture at the junction of the waist and proximal retrograde intraosseous blood supply also predispose the pole (arrow). proximal pole to ischemic conditions.12

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Figure 5 (A–D) Nonunited scaphoid waist fracture in a 44-year-old male patient 13 years after trauma. (A) Posteroanterior radiograph of the left wrist shows a nonunited scaphoid waist fracture (arrow). (B) Coronal reformatted and (C) sagittal oblique reformatted computed tomography (CT) images of the left wrist better demonstrate sclerosis and cystic changes about the fracture line (arrows). (D) On the sagittal oblique reformatted CT image, note humpback deformity at the dorsal aspect of the scaphoid (arrow) and measurements of the scaphoid height (double- headed black arrow) and length (double-headed white arrow).

Distribution and Classification Several classification systems of scaphoid fractures have of Scaphoid Fractures been proposed in the literature. The Russe classification divides the fractures on the basis of the orientation of the A total of 65% of scaphoid fractures involve the waist, 15% the

fracture line into horizontal oblique, transverse and vertical Downloaded by: University of Colorado Denver. Copyrighted material. proximal pole, 10% the distal body, 8% the volar tubercle, and oblique, with the latter considered to be the most unsta- 2% the distal articular surface.13 ble.14 In the Herbert classification,15 displacement or instability of a scaphoid fracture is defined as displacement of the fracture fragment by at least 1 mm or radiolunate angulation >15 degrees or scapholunate angulation >60 degrees. Scaphoid fractures are divided into type A, stable acute (fracture of the tubercle or incomplete waist); type B, unstable acute (distal oblique, complete waist, proximal pole fracture or transscaphoid perilunate dislocation of the carpus); type C, delayed union; and type D, established nonunion (fibrous union or pseudoarthrosis) (►Fig. 1415). Recently, Ho and Wong proposed an additional classification dividing scaphoid fractures into type A, distal pole fractures (A1: of the scaphoid tubercle, A2: distal articular); Figure 6 An 18-year-old male patient with scaphoid waist fracture type B, body fractures (B1: distal third, B2: middle third, B3: delayed union. Coronal T2-weighted fat-suppressed magnetic proximal third, B4: sulcal fracture); type C, proximal pole resonance image of the left wrist shows a nonunited scaphoid waist fractures; and type D, transscaphoid perilunate fracture fracture with high signal intensity at the fracture line (arrow) 16 suggestive of instability along with bone marrow edema in both dislocation. In a recent epidemiology study, 68.9% of proximal and distal poles. scaphoid fractures were unstable.17

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Figure 7 (A–E) A 43-year-old female patient with a nonunited scaphoid waist fracture. (A) posteroanterior (PA) ulnar deviation radiograph of the left wrist shows a nonunited scaphoid waist fracture (solid head arrow). Note cystic change about the fracture site indicative of instability/motion and sclerotic proximal pole (arrow) that appeared viable at surgery. (B) T1-weighted coronal magnetic resonance (MR) image shows low signal intensity fracture line (solid head arrow) with cystic change and intermediate signal intensity in the proximal pole (arrow). (C) Coronal short tau inversion recovery MR image shows low signal intensity fracture line with adjacent cystic change (arrow) and high signal intensity in the proximal and distal scaphoid poles and in the lunate (solid head arrows), with (D) enhancement on the T1-weighted fat-suppressed coronal MR image. High signal intensity and enhancement in the lunate are probably related to carpal instability. (E) The fracture was treated with open reduction and internal fixation and bone grafting after debridement of nonunion; note variable pitch volarly placed cannulated screw transfixing the fracture site with bone graft material at the fracture site that was harvested from the distal radius. The bone graft donor side was filled with the radiodense bone graft substitute.

Natural History, Scaphoid Fracture Healing, require surgical treatment5 because they have an estimated 20 and Complications 50% nonunion rate with nonsurgical treatment due to their Downloaded by: University of Colorado Denver. Copyrighted material. association with ligament disruption, persistent motion The prognosis of distal pole fractures is better than proximal (►Fig. 7), angulation, fracture fragment displacement,5 and/ pole fractures due to the scaphoid's retrograde blood supply.6 or soft tissue interposition.21 Approximately 12% of scaphoid Properly immobilized nondisplaced stable scaphoid fractures fractures fail to unite and require internal fixation with bone typically heal in 8 to 12 weeks (►Fig. 2).5 grafting.21 Disruption of the palmar capsular carpal ligaments and the Development of osteonecrosis is directly related to the scapholunate interosseous ligament, as seen in perilunate position of the fracture line. Fractures of the middle third are dislocations, allows the scaphoid to assume a flexed position associated with a 30% incidence of osteonecrosis (►Fig. 9), and the lunate an extended position with the wrist in neutral and fractures of the proximal fifth are associated with a position. With an unstable scaphoid fracture, the distal nearly 100% incidence of osteonecrosis (►Fig. 8). Earlier scaphoid fragment flexes toward the palm along with the development of osteonecrosis occurs with nonunion of the distal carpal row while the proximal fragment migrates proximal third of the scaphoid when compared with the dorsally with the lunate. This leads to the “humpback” middle third.22 deformity of the scaphoid seen with healed or nonunited Scaphoid nonunion has been associated with the develop- although formerly unstable angulated scaphoid fractures ment of late osteoarthritis of the wrist, with temporal pro- (►Fig. 5D).18 gression in a pattern that is commonly referred to as scaphoid Scaphoid fracture nonunion may result from delayed nonunion advanced collapse, or SNAC, wrist (►Fig. 10).23 diagnosis, inadequate or improper treatment, and patient- Displaced fractures typically progress to symptomatic arthri- related factors (►Figs. 4–7).19 Unstable scaphoid fractures tis faster and more extensively than nondisplaced fractures.

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Figure 10 (A, B) Scaphoid nonunion advanced collapse in a 56-year- old man 20 years after scaphoid fracture. (A) Posteroanterior radiograph of the left wrist shows advanced osteoarthritis of the radioscaphoid joint between the distal scaphoid fracture fragment and the Figure 8 A 40-year-old male patient with scaphoid fracture nonunion radial styloid with near complete resorption of the proximal scaphoid and proximal pole osteonecrosis. Posteroanterior radiograph of the pole (arrow) and additional narrowing of the scaphocapitate and left wrist shows a nonunited fracture of the proximal scaphoid pole capitolunate joints and of the basal joints of the thumb. (B) Lateral associated with moderate volume loss of the proximal pole (arrow). radiograph shows dorsal tilt of the lunate consistent with dorsal Courtesy of Winnie Mar, M.D., Chicago, IL. intercalated segment instability deformity (arrow).

Following the involvement of the radioscaphoid joint, osteo- tory evaluations of scaphoid fractures and treatment follow-up arthritis progresses to the scaphocapitate and capitolunate and depicts 70 to 90% of acute scaphoid fractures (►Fig. 1).25,26 joints. The radiolunate joint is preserved.24 A PA or a PA-oblique radiograph may also be obtained with a clenched ﬁst or with the tube angled toward the elbow and Imaging of Scaphoid Fractures with the wrist in ulnar deviation to accentuate scaphoid and Their Complications extension, which may help to identify scapholunate interval widening or a fracture line not visible on a conventional PA Imaging of scaphoid fractures and their complications is radiograph.5 True lateral radiographs27 allow measurements performed by radiography, computed tomography (CT), mag- of the scapholunate angle (normal 30 to 60 degrees measured netic resonance imaging (MRI), nuclear medicine bone scan, between the long axis of the scaphoid and the midplane axis of and ultrasonography. Each of these imaging modalities has its the lunate) and capitolunate angle (normal <30 degrees strengths and limitations.21 measured between the long axis of the capitate and the Radiography of the affected wrist using four standard midplane axis of the lunate). A scapholunate angle >80 imaging projections (posteroanterior [PA], 45 degrees external degrees or <30 degrees usually indicates an instability pattern oblique, lateral, and PA with ulnar deviation) enables satisfac- or dorsal tilting of the proximal scaphoid fracture fragment.18 Downloaded by: University of Colorado Denver. Copyrighted material.

Figure 9 (A–C) A 23-year-old male patient with nonunited scaphoid waist fracture and early osteonecrosis of the proximal pole. (A) T1-weighted coronal magnetic resonance (MR) image of the left wrist shows a nonunited scaphoid waist fracture (solid head arrow), mildly decreased signal intensity in the distal pole (white arrow), and relatively normal signal in the proximal pole (open arrow) consistent with mummiﬁed fat (early osteonecrosis) of the proximal pole. (B) Coronal proton-density-weighted fat-suppressed MR image of the left wrist shows high signal intensity at thefracturesite(solidheadarrow),highsignalinthedistalpole(white arrow), and low signal in the proximal pole (open arrow). (C) Coronal contrast-enhanced T1-weighted fat-suppressed MR image of the left wrist shows enhancement at the fracture site (solid head arrow) and in the distal scaphoid pole (white arrow) with no enhancement of the necrotic proximal pole (open arrow).

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Figure 11 (A, B) Artist drawing of the (A) dorsal and (B) volar branches of the radial artery (thin arrows) that provide the blood supply to scaphoid bone in a retrograde fashion.

If further characterization of an acute radiographically 1.5 mm in the coronal and sagittal oblique, axial, and direct apparent scaphoid fracture is undertaken for treatment sagittal planes. The sagittal oblique reformatted images are management, CT examination is frequently performed.21,28 prescribed from the coronal reformatted images in the long In the principal author's institution, CT examination of the axis of the scaphoid and are frequently the most valuable in affected wrist is performed on multidetector CTunits with the the evaluation of scaphoid fractures. Tridimensional surface- patient in prone position on the CT table, arm extended above rendered reformatted images may also be obtained. the head (so-called superman position), and palm down. Approximately 16% of all scaphoid fractures are radio- Images are reformatted at 0.5 mm with an interval of graphically occult (►Fig. 3A).29 In the acute trauma setting, if a scaphoid fracture is clinically suspected and not seen on the initial radiographs, conservative treatment with splinting and follow-up radiographs in 2 weeks is typically performed.30 Alternatively, MR imaging may be performed to evaluate for radiographically occult scaphoid fracture (►Figs. 3B and C) and other possible associated injuries and

is considered a cost-effective method for excluding occult Downloaded by: University of Colorado Denver. Copyrighted material. fractures and bone contusions, thus avoiding unnecessary immobilization, radiation exposure, and clinical follow-up.31 Recent studies indicate that CT and MRI provide overall comparable results in the evaluation of radiographically occult scaphoid fractures,32,33 but MRI can depict bone marrow edema and is better for the evaluation of the associated soft tissue injuries.33 Technetium bone scans show increased uptake at the fracture site and can potentially show decreased uptake over a proximal scaphoid fragment with decreased vascularity and possible osteonecrosis.34 However, scintigraphy does not provide information regarding fracture fragment displacement or angulation. Additionally, scintigraphy cannot help distinguish bone marrow edema or bone contusion, both of which may be associated with increased osteoblastic activity due to trabecular microfractures from a fracture.21 Figure 12 Striped diagram superimposed on posteroanterior radiograph of the right wrist represents zone of vulnerability in the pathway A few studies have been published on ultrasonographic of the major palmar wrist ligaments. C, capitate; H, hamate; L, lunate; assessment of acute scaphoid fractures with variable re- – P,pisiform;S,scaphoid;Td,trapezoid;Tm,trapezium;Tr,triquetrum. sults.35 37 In one study, ultrasonography showed 84%

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Figure 13 (A–C) Transscaphoid transulnar styloid perilunate fracture dislocation in a 19-year-old male patient treated with closed reduction and subsequent open reduction and internal fixation. (A) Posteroanterior (PA) radiograph of the left wrist shows displaced comminuted scaphoid waist fracture (arrow), mildly displaced ulnar styloid fracture (solid head arrow) with disruption of normal carpal arcs. (B) Lateral radiograph of the left wrist shows dorsal displacement of the capitate (solid head arrow) in respect to the lunate (open white arrow) that articulates with the distal radius, distal pole of a displaced scaphoid fracture (open black arrow), and completely volarly displaced and rotated proximal scaphoid pole that partially overlies the distal pole. The triquetrum is dorsi-positioned (arrow). Small bone fragments proximal to the triquetrum originate from the ulnar styloid and possibly from the dorsal radial articular surface. (C) Postoperative PA radiograph of the left wrist shows a variable pitch volarly placed screw transfixing the comminuted scaphoid waist fracture (arrow) and three Kirschner wires transfixing the scapholunate, lunotriquetral, and scaphocapitate joints. Note ulnar styloid fracture (solid head arrow) and skin staples.

accuracy and 91% specificity in the detection of acute scaph- periosteal elevation.37 In the first author's institution, ultra- oid fractures. However, the sensitivity was only 50%. These sonography of the scaphoid bone is not routinely used for the authors concluded that ultrasound examination is unreliable evaluation of occult fractures but is occasionally performed as for the diagnosis of acute scaphoid fractures.35 Others re- a part of routine wrist ultrasonography (►Fig. 15). Further ported better results,36,37 with 100% sensitivity, 98% specific- limitations of ultrasonography are its operator dependent ity, and 98% accuracy in the detection of radiographically nature and difficulty appreciating full fracture extent. occult acute scaphoid waist fractures in the study by Hauger In healing fractures, CT imaging is more accurate5 in et al.36 The key imaging findings of the occult acute scaphoid assessing the crossing bone trabeculae (mineralization of fractures were related to cortical discontinuity36 and/or immature osteoid) than radiography, which lacks a high Downloaded by: University of Colorado Denver. Copyrighted material.

Figure 14 Herbert classiﬁcation of scaphoid fractures.

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Figure 15 (A, B) Ultrasonography in a 60-year-old male patient with a known long-standing scaphoid fracture nonunion sustained in high school. (A) Ultrasonography of the right scaphoid bone obtained in long axis shows a marked deformity of the central portion of the scaphoid bone. (B) The left scaphoid bone was imaged for comparison purposes and shows normal contour. DP, distal pole; PP, proximal pole. degree of sensitivity and speciﬁcity.38,39 MRI was shown to fracture line with normal trabeculae bridging the fracture or detect early bony union in 45% of patients who were not nonunion, with MRI being the most sensitive imaging mo- considered to have a healed fracture both clinically and dality (►Fig. 16).21 The MRI criterion for the presence of bony radiographically.40 Healed fractures (►Figs. 2B and 3D)and union on T1-weighted images is normal high signal intensity healed nonunions after bone grafting show obliteration of the bone marrow crossing the previous fracture line.41 Downloaded by: University of Colorado Denver. Copyrighted material.

Figure 16 (A–E) A 28-year-old male patient with a history of scaphoid fracture 2 years earlier and persistent pain and functional limitation of the wrist. (A) The preoperative radiograph and (B) coronal T1-weighted magnetic resonance (MR) image show pseudarthrosis in the waist of the scaphoid bone with sclerosis in the bony surfaces on both sides (arrows). (C) The 3-month postoperative radiograph shows diffuse osteopenia due to immobilization and bone bridging on both sides of the graft (open arrows). (D) The corresponding postoperative coronal T1-weighted and (E) coronal fat-suppressed contrast-enhanced T1-weighted MR images show fusion of the bone marrow between the proximal and distal poles and the bone graft (open arrows). The enhancement throughout the scaphoid bone is suggesting normal bone graft incorporation. Enhancing bone marrow edema is seen in the lunate, secondary to previous surgical manipulations.

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Figure 17 (A–D) Scaphoid nonunion with good proximal pole perfusion in a 28-year-old man. (A) Coronal T1-weighted magnetic resonance (MR) image of the left wrist shows a nonunited fracture of the proximal scaphoid pole (arrow) with sclerosis of the fracture margins and low signal intensity in the proximal pole and proximal aspect of the distal pole. (B) Increased signal intensity is seen at the fracture site (arrow) and in the proximal and distal scaphoid poles on the coronal short tau inversion recovery image. (C) The region of interest in the proximal scaphoid pole is outlined with a red line and the reference area in the distal pole with a dashed yellow line on coronal T1-weighted fat-suppressed perfusion MR image. (D) The time-signal intensity curve of the proximal scaphoid pole (red curve) shows a good perfusion similar to the distal pole (yellow dashed curve).

Radiographic features of fracture nonunion include scle- deformity (►Fig. 5D)45,46 and allow acquisition of several rosis of the fracture margins, peri-fracture cyst formation, measurements that may be useful in preoperative planning ►

peri-fracture bone resorption, and subsequently peri-scaph- such as height-to-length ratio ( Fig. 5D), dorsal cortical Downloaded by: University of Colorado Denver. Copyrighted material. oid osteoarthritis (►Figs. 4, 5A,and7A).42 On radiographs, angle, and lateral intrascaphoid angle.47,48 osteonecrosis most frequently becomes apparent 3 to 6 months after injury, with increased density and progressive Magnetic Resonance Imaging collapse of the proximal pole fragment (►Fig. 8). However, in At the present time, MR imaging without contrast is consid- the healing fracture, mild to moderate sclerosis of the proxi- ered the imaging modality of choice in the evaluation of mal pole may be a transient phenomenon due to altered bone radiographically occult scaphoid fractures (►Figs. 3B and C) – remodeling and probably indicates a reversible ischemic state and bone contusions.21,49 57 Noncontrast and contrast-en- with revascularization and new bone deposition (►Fig. 16D) hanced MR imaging is typically performed for the evaluation rather than established osteonecrosis.43,44 A sclerotic proxi- of scaphoid fracture nonunion (►Figs. 7B–D), osteonecrosis mal pole may bleed and be viable or may be ischemic at (►Fig. 9), fracture healing, bone graft incorporation – surgery (►Fig. 7A).43 (►Fig. 16),58 61 and revitalization after bone grafting, partic- CT parallels the radiographic findings, and with its excel- ularly in patients without surgical hardware.21,62,63 lent spatial resolution, it allows better assessment of the Acute scaphoid fractures are frequently associated with fracture line, displacement and angulation of the fracture injury to the intrinsic interosseous and extrinsic wrist fragments, as well as cystic change and sclerosis of the ligaments,21,57 which can be evaluated with both high- fracture fragments (►Figs. 5B–D).5 The use of a metal reduc- resolution MR imaging and MR arthrography.21 MR imaging – tion artifact with surgical hardware enables satisfactory showed 100% sensitivity and 100% specificity,29,53 55 and in evaluation following screw fixation. Sagittal oblique CT im- the immature skeleton, a 100% negative predictive value51 ages allow better visualization of posttraumatic humpback in detection of scaphoid fractures. On MR imaging, the acute

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Figure 18 (A–D) Scaphoid nonunion with poor proximal pole perfusion in a 25-year-old man. (A) Coronal T1-weighted magnetic resonance (MR) image of the right wrist shows a nonunited fracture of the proximal scaphoid pole (arrow) with sclerosis of the fracture margins and mild intermediate signal intensity in the proximal and distal poles about the fracture line. (B) Increased signal intensity is seen at the fracture site (arrow), in the distal aspect of the proximal pole, and in the distal scaphoid pole on the coronal short tau inversion recovery image. (C) The region of interest in the proximal scaphoid pole is outlined with a yellow dashed line and the reference area in the distal pole with a red line on the coronal T1-weighted fat-suppressed perfusion MR image. (D) The time-signal intensity curve of the proximal scaphoid pole (yellow dashed curve) shows poor perfusion when compared with the distal pole (red curve).

fracture line shows low signal intensity on all sequences performed on a 3-T MR machine with a dedicated quadrature ►

( Figs. 3B and C). Associated with the fracture line is bone transmit-receive wrist coil. Downloaded by: University of Colorado Denver. Copyrighted material. marrow edema, which displays high signal intensity on With the presence of scaphoid fracture nonunion, in- fluid-sensitive sequences (►Fig. 3C) and intermediate to creased signal at the fracture site on the fluid-sensitive low signal intensity on the T1-weighted sequences sequences (►Fig. 6) and cystic change at the fracture site (►Fig. 3B). Bone contusion, which is a synonym for bone (►Figs. 7B–D) indicate instability.21 bruising, represents trabecular microfractures and show On unenhanced MR images, some authors have reported a bone marrow edema on MR imaging without a discernible good correlation between hypointense signal on T1-weighted fracture line.21 and T2-weighted images and poor vascularity of the proximal MR imaging is performed with the patient in the prone scaphoid pole19,64 with less encouraging results reported by position and the arm extended above the head on 1.5-T or 3-T others.61 Hypointense or isointense signal, with regard to MRI scanners. The imaging protocol typically includes surrounding bone marrow, on T1-weighted sequences, may T1-weighted, fluid sensitive (short tau inversion recovery, be explained by mature callus formation, which occurs in fat-suppressed proton density/T2-weighted), 3D gradient both viable and nonviable poles (►Fig. 17A).61 A total of 80 to recalled echo (tridimensional gradient echo), and for the 90% of both viable and nonviable scaphoid poles appeared assessment of scaphoid fractures nonunions, contrast en- hyperintense on fluid-sensitive sequences in the study by hanced T1-weighted with fat suppression sequences in coro- Donati and collaborators. Hyperintense signal intensity on nal, sagittal oblique (planned from direct coronals), axial, and fluid-sensitive sequences may also be seen in both viable sagittal planes with a dedicated wrist coil or a small surface (►Figs. 7C and 17B) and nonviable (►Fig. 18B)proximal coil, usually using a 2-mm or 3-mm slice thickness. In the first scaphoid poles, which may correspond to various histological author's institution, whenever possible, MR imaging is findings such are immature callus, bone marrow edema,

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hemorrhage, and fibrosis.65 One can appreciate, therefore, sis.61 MRI has been shown to be useful in assessing that in many instances, determining proximal pole viability vascularized bone graft incorporation and revascularization based on noncontrast-enhanced signal change is not of the proximal scaphoid pole in patients with scaphoid straightforward. nonunion with osteonecrosis of the proximal pole.62,63 In recent years, contrast-enhanced MR imaging has be- come the standard imaging method for the assessment of 58–60 Treatment of Scaphoid Fractures and Their scaphoid viability. Cerezal and coworkers reported a Complications good correlation between the degree of enhancement and viability of the proximal scaphoid pole. Lack of increased The appropriate treatment of scaphoid fractures is still some- signal on the fluid-sensitive sequences (►Fig. 9B) and lack of times controversial and depends on patient factors and enhancement on the fat-suppressed T1-weighted sequences surgeon preference. Other decision-making factors are the after intravenous administration of gadolinium-based con- potential for morbidity from prolonged immobilization, the trast agents (►Fig. 9C) is indicative of ischemia or osteonec- occupation of the patient, and with delayed unions, lack of rosis.58 Additionally, T1-weighted sequences alone are not evidence of healing after 3 to 4 months of conservative useful because in patients in whom normal signal intensity is treatment.3 seen on T1-weighted images, early necrosis with mummified Acute fractures of the distal scaphoid pole and tubercle are fat is possible (►Fig. 9A).58 typically treated conservatively in a cast, with or without a However, the usefulness of gadolinium-enhanced MR thumb spica component. Nondisplaced acute scaphoid waist imaging in the evaluation of proximal scaphoid pole viability fractures can be treated conservatively in a short or long arm is still debatable. Other authors did not find a significant cast, or operatively, especially in high-demand patients or correlation between the degree of contrast enhancement and those with associated distal radius fractures.3,70,71 Displaced healing of scaphoid fractures.66,67 Enhancement of the prox- scaphoid waist fractures and proximal pole fractures,3 as well imal pole may be attributed to viability (►Fig. 17C)orto as fractures complicated by nonunion or nonunion with fibrovascular tissue following osteonecrosis with areas of osteonecrosis, are usually treated operatively.42 Transsca- vascularized bone in a patchy distribution.64,68,69 Contrast phoid perilunate dislocations, and other types of perilunate enhancement may also be caused by invasion of the proximal dislocations associated with scaphoid fractures, such is transscaphoid pole by reactive inflammatory tissue originating scaphoid transcapitate perilunate dislocation, are treated from the site of nonunion.30 with urgent closed reduction followed by operative For the assessment of scaphoid nonunions and proximal treatment.72,73 pole viability, in addition to static contrast-enhanced sequen- The goal for treatment of scaphoid nonunion is to achieve ces (►Figs. 7D, 9C, and 16E), perfusion/dynamic contrast- healing and to correct any carpal deformity that may lead to enhanced imaging may also be used (►Figs. 17 and 18). Fat- osteoarthritis.45 Fractures are considered to be nonunited if suppressed fast spin-echo T1-weighted imaging is performed the fracture line persists 6 months after injury. Nonoperative in the coronal or sagittal-oblique plane depending on the best treatment of nondisplaced scaphoid nonunion is debatable. visualized longitudinal mid-axis of the scaphoid, with dy- Suggestions are a very long period of cast immobilization (2 to namic imaging after intravenous injection of a contrast 6 months), with or without bone stimulation. Generally, this medium bolus. Time-intensity curves in the proximal and is reserved for patients with a contraindication for surgery.74 distal scaphoid poles are then compared, with a viable The surgical treatment is considered much more 42,74 ►

proximal pole usually demonstrating similar enhancement effective. Fig. 19 outlines the treatment algorithm for Downloaded by: University of Colorado Denver. Copyrighted material. to the distal pole (►Fig. 17D), but a nonviable proximal pole scaphoid fractures and their complications used in the first demonstrating poor enhancement (►Fig. 18D) compared author's institution. with the viable distal pole. As a reference standard, an area The assessment of viability of the scaphoid fracture frag- in the radial styloid or capitate may also be used.61 ments is key in the treatment of scaphoid fracture nonun- In their recent retrospective study on twenty-eight pa- ions.43,45,46 Proximal pole vascularity may be assessed tients, Donati and collaborators correlated imaging findings operatively by observing punctate bleeding points in the on noncontrast MR images with those of a dynamic contrast- proximal pole bone, and, although it cannot be predicted enhanced study and with surgical and/or histological exami- by preoperative radiography43 can be more fully assessed by nation for the presence of osteonecrosis.61 These authors preoperative MRI examination. found that the findings at histological examination including In case of nonviability of the proximal scaphoid pole, a viable bone, necrotic bone, and callus formation did not vascularized rather than a standard nonvascularized bone – correlate with those at dynamic gadolinium-enhanced MR graft is preferred with good results reported.74 76 imaging. Furthermore, the diagnostic performance of dynam- In patients with fracture nonunion of the proximal pole or ic gadolinium-enhanced MR imaging in the evaluation of waist without osteonecrosis, debridement of the nonunion scaphoid viability was inferior to that of a standard non- and correction of the deformity is performed with conven- contrast-enhanced MR imaging protocol. Donati and collab- tional bone grafting with or without cannulated screw fixa- orators concluded that the dynamic contrast-enhanced MR tion rather than Kirschner wires. A volar or dorsal approach is imaging may not be needed in patients with scaphoid frac- used at surgery depending on the surgeon's preference. tures nonunion to evaluate for the presence of osteonecro- Central positioning of the fixating screw is important

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Figure 19 Treatment algorithm of scaphoid fractures and their complications that is used in the ﬁrst author's institution. AVN, avascular necrosis (osteonecrosis); DJD, degenerative joint disease; ORIF, operative reduction and internal ﬁxation; PCF, partial carpal fusion; PRC, proximal row carpectomy; SNAC, scaphoid nonunion advanced collapse; TWA, total wrist arthroplasty; “Vascular,” vascularized bone graft.

Figure 20 (A–C) Scaphoid fracture nonunion in a 15-year-old male patient. (A) Intraoperative photograph of the right wrist shows the nonunion

site in the region of the scaphoid waist (arrow) adjacent to the ﬂexor carpi radialis tendon (solid head arrow). (B) Note debrided scaphoid nonunion Downloaded by: University of Colorado Denver. Copyrighted material. site (arrow) and bone graft donor site in the distal radius (solid head arrow). (C) Postoperative posteroanterior radiograph of the right wrist obtained 2 weeks after surgery shows a volarly placed variable pitch cannulated screw transﬁxing the scaphoid waist fracture and bone graft donor site in the distal radial metaphysis (arrow).

(►Fig. 20).42,74 In patients with long-standing nonunions and Malunited scaphoid fractures usually show flexion defor- failed previous surgeries, vascularized bone graft should be mity and foreshortening that may cause an alteration of considered. In patients with scaphoid nonunion with proxi- carpal mechanics, with resultant osteoarthritis causing mal pole osteonecrosis, vascularized bone graft from the pain, weakness, and decreased motion. Symptomatic mal- distal radius with an attached recurrent branch of the radial unions may be surgically corrected with osteotomy, bone artery (1,2 intercompartmental supraretinacular artery) with grafting, and surgical fixation.78 or without cannulated screw fixation is frequently used with 42,74 a dorsal surgical approach. This technique was initially Conclusion described by Zaidemberg et al.77 A high success union rate with this technique was reported in 2009 by Waitayawinyu Imaging of scaphoid fractures and their complications should with 93% of fractures united in 30 patients.75 Other types of start with four-view radiographs. CT is the imaging modality nonvascularized and vascularized bone grafts may also be of choice to evaluate displacement of the fracture site and utilized.74 fracture healing/bone graft incorporation in the presence of

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