Forearm Instability
2013; Elsevier BV; Volume: 39; Issue: 1 Linguagem: Inglês
10.1016/j.jhsa.2013.07.010
ISSN1531-6564
AutoresBryan J. Loeffler, Jennifer B. Green, David S. Zelouf,
Tópico(s)Bone fractures and treatments
ResumoForearm instability results from trauma, which disrupts the radial head, the interosseous membrane, and the triangular fibrocartilage complex. Inadequate treatment of injuries to these forearm stabilizers may result in the complex problem of chronic longitudinal forearm instability. Delayed recognition and/or treatment of injuries producing forearm dissociation has led to poor patient outcomes, which makes timely recognition of the injury pattern imperative. This article discusses relevant aspects of forearm anatomy and current concepts in the diagnosis and treatment options for this complex injury pattern. Forearm instability results from trauma, which disrupts the radial head, the interosseous membrane, and the triangular fibrocartilage complex. Inadequate treatment of injuries to these forearm stabilizers may result in the complex problem of chronic longitudinal forearm instability. Delayed recognition and/or treatment of injuries producing forearm dissociation has led to poor patient outcomes, which makes timely recognition of the injury pattern imperative. This article discusses relevant aspects of forearm anatomy and current concepts in the diagnosis and treatment options for this complex injury pattern. CME Information and DisclosuresThe Review Section of JHS will contain at least 3 clinically relevant articles selected by the editor to be offered for CME in each issue. For CME credit, the participant must read the articles in print or online and correctly answer all related questions through an online examination. The questions on the test are designed to make the reader think and will occasionally require the reader to go back and scrutinize the article for details.The JHS CME Activity fee of $20.00 includes the exam questions/answers only and does not include access to the JHS articles referenced.Statement of Need: This CME activity was developed by the JHS review section editors and review article authors as a convenient education tool to help increase or affirm reader's knowledge. The overall goal of the activity is for participants to evaluate the appropriateness of clinical data and apply it to their practice and the provision of patient care.Accreditation: The ASSH is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.AMA PRA Credit Designation: The American Society for Surgery of the Hand designates this Journal-Based CME activity for a maximum of 2.00 "AMA PRA Category 1 Credits™". Physicians should claim only the credit commensurate with the extent of their participation in the activity.ASSH Disclaimer: The material presented in this CME activity is made available by the ASSH for educational purposes only. This material is not intended to represent the only methods or the best procedures appropriate for the medical situation(s) discussed, but rather it is intended to present an approach, view, statement, or opinion of the authors that may be helpful, or of interest, to other practitioners. Examinees agree to participate in this medical education activity, sponsored by the ASSH, with full knowledge and awareness that they waive any claim they may have against the ASSH for reliance on any information presented. The approval of the US Food and Drug Administration is required for procedures and drugs that are considered experimental. Instrumentation systems discussed or reviewed during this educational activity may not yet have received FDA approval.Provider Information can be found at http://www.assh.org/Pages/ContactUs.aspx.Technical Requirements for the Online Examination can be found at http://jhandsurg.org/cme/home.Privacy Policy can be found at http://www.assh.org/pages/ASSHPrivacyPolicy.aspx.ASSH Disclosure Policy: As a provider accredited by the ACCME, the ASSH must ensure balance, independence, objectivity, and scientific rigor in all its activities.Disclosures for this ArticleEditorsGhazi M. Rayan, MD, has no relevant conflicts of interest to disclose.AuthorsAll authors of this journal-based CME activity have no relevant conflicts of interest to disclose. In the printed or PDF version of this article, author affiliations can be found at the bottom of the first page.PlannersGhazi M. Rayan, MD, has no relevant conflicts of interest to disclose. The editorial and education staff involved with this journal-based CME activity has no relevant conflicts of interest to disclose.Learning Objectives•Elucidate the anatomy and biomechanics of the forearm.•List the stabilizers of the forearm.•Clarify the pathomechanics of forearm instability.•Discuss the clinical presentation and diagnostic tools for forearm instability.•Explain the management of forearm instability.Deadline: Each examination purchased in 2014 must be completed by January 31, 2015, to be eligible for CME. A certificate will be issued upon completion of the activity. Estimated time to complete each month's JHS CME activity is up to 2 hours. Copyright © 2014 by the American Society for Surgery of the Hand. All rights reserved.Instability of the forearm results from traumatic disruption of the primary and secondary stabilizers of the radius and ulna. Left untreated, forearm instability leads to forearm and wrist pain, limited forearm motion, and deformity at the wrist. Knowledge of the normal anatomy and biomechanics of the forearm is critical to fully understand the complexity of forearm instability and its treatment options.Curr and Coe1Curr J.F. Coe W.A. Dislocation of the inferior radio-ulnar joint.Br J Surg. 1946; 34: 74-77Crossref PubMed Scopus (69) Google Scholar provided the first documentation of an acute forearm instability injury pattern in 1946. However, in 1951, Essex-Lopresti2Essex-Lopresti P. Fractures of the radial head with distal radio-ulnar dislocation: report of two cases.J Bone Joint Surg Br. 1951; 33: 244-247Google Scholar further described an injury pattern of radial head fracture, rupture of the interosseous membrane (IOM), and distal radioulnar joint (DRUJ) disruption resulting from a traumatic axial load transmitted from the wrist to the elbow. Because of his detailed description, the injury pattern was assigned the eponym Essex-Lopresti injury.2Essex-Lopresti P. Fractures of the radial head with distal radio-ulnar dislocation: report of two cases.J Bone Joint Surg Br. 1951; 33: 244-247Google Scholar In 1992, Trousdale et al3Trousdale R.T. Amadio P.C. Cooney W.P. Morrey B.F. Radio-ulnar dissociation. A review of twenty cases.J Bone Joint Surg Am. 1992; 74: 1486-1497PubMed Google Scholar described the chronic sequelae of proximal migration of the radius and longitudinal radioulnar dissociation that occur after this injury pattern. Since that time, considerable research has been performed to describe the anatomy and biomechanics of the forearm axis as well as injury patterns that disrupt its stability. This novel research has led to a greater understanding of these injury patterns and additional treatment options for this complex problem. Trousdale et al3Trousdale R.T. Amadio P.C. Cooney W.P. Morrey B.F. Radio-ulnar dissociation. A review of twenty cases.J Bone Joint Surg Am. 1992; 74: 1486-1497PubMed Google Scholar reported that only 25% of patients with longitudinal radioulnar dissociation were fully diagnosed upon initial presentation, and only 20% of patients with delayed diagnosis and subsequent treatment had positive outcomes. This study demonstrates the importance of early recognition of the injury patterns associated with forearm instability as well as the need for appropriate initial treatment to improve the likelihood of positive results.An intact radial head, IOM, and triangular fibrocartilage complex (TFCC) all contribute to axial stability of the forearm axis. A severe axial compression force through the forearm may injure 1 or more of these stabilizers. Some injuries result in isolated radial head or neck fractures without disruption of axial forearm stability, whereas others result in a spectrum of severity that may involve a radial head or neck fracture, or both, along with concomitant injuries to the IOM and TFCC. With disruption of these stabilizers and inadequate treatment, longitudinal radioulnar dissociation typically occurs, resulting in proximal migration of the radius, altered loading patterns through the forearm and wrist, and forearm instability. Forearm destabilization, if recognized acutely, requires immediate surgical intervention with repair or replacement of the radial head. In addition, treatment of concomitant IOM and TFCC injuries should be considered. If the forearm instability pattern is unrecognized, chronic insufficiency of the IOM with resultant symptoms at the elbow and wrist can be expected.4Failla J.M. Jacobson J. van Holsbeeck M. Ultrasound diagnosis and surgical pathology of the torn interosseous membrane in forearm fractures/dislocations.J Hand Surg Am. 1999; 24: 257-266Abstract Full Text Full Text PDF PubMed Scopus (67) Google ScholarThe purpose of this article is to review the anatomy and biomechanics of the forearm stabilizers, to discuss early recognition of forearm instability patterns, and to review the treatment options for acute and chronic cases of forearm instability.Anatomy and Biomechanics of Forearm StabilizersThe forearm unit consists of the radius and ulna, which are bound proximally by the proximal radioulnar joint (PRUJ), centrally by the IOM, and distally by the DRUJ. The primary functions of the forearm unit are (1) to provide stability and maintain anatomical relationships of the radius and ulna, thus allowing for optimal pronosupination, (2) to facilitate load transfer from the radius to the ulna as force is transmitted from the wrist to the elbow, and (3) to serve as an attachment site for muscles responsible for forearm, wrist, and finger motion. Axial stability of the forearm is attributed primarily to the radial head and secondarily to the IOM and TFCC.5Morrey B.F. Chao E.Y. Hui F.C. Biomechanical study of the elbow following excision of the radial head.J Bone Joint Surg Am. 1979; 61: 63-68PubMed Google Scholar The radial head is the primary stabilizer of the forearm because the articulation between the radial head and the capitellum prevents proximal migration of the radius.6Rabinowitz R.S. Light T.R. Havey R.M. et al.The role of the interosseous membrane and triangular fibrocartilage complex in forearm stability.J Hand Surg Am. 1994; 19: 385-393Abstract Full Text PDF PubMed Scopus (126) Google Scholar The PRUJ is the site where the radial head articulates with the lesser sigmoid notch of the ulna, and the annular ligament maintains the radial head in this position. The radial collateral ligament and accessory radial collateral ligament also contribute to stabilizing the radial head in its anatomical position.The IOM provides a central connection between the radius and the ulna, and recent research has elucidated its importance in forearm stability. The anatomy of the IOM allows multiple functions, including load transfer from the radius to the ulna as well as maintenance of longitudinal and transverse forearm stability. In addition, it provides support during forearm rotation, serves as an origin for the wrist flexors and extensors, and separates the volar and dorsal compartments of the forearm.Noda et al7Noda K. Goto A. Murase T. Sugamoto K. Yoshikawa H. Moritomo H. Interosseous membrane of the forearm: an anatomical study of ligament attachment locations.J Hand Surg Am. 2009; 34: 415-422Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar recently described a total of 5 distinct components to the IOM ligaments over 3 portions of the forearm. The proximal membranous portion travels in a distal direction and consists of the proximal oblique and dorsal accessory cords. The middle ligamentous complex supplies the majority of the stiffness to the IOM and comprises the central band and accessory band. The central band is a very stout and consistent structure, which originates on the radius and is oriented distally an average of 21° to the longitudinal axis of the ulna toward its insertion on the ulna8Skahen III, J.R. Palmer A.K. Werner F.W. Fortino M.D. Reconstruction of the interosseous membrane of the forearm in cadavers.J Hand Surg Am. 1997; 22: 986-994Abstract Full Text PDF PubMed Scopus (92) Google Scholar (Fig. 1). The distal membranous portion of the IOM is the distal oblique bundle, which exhibits a more oblique trajectory. These segments of the IOM help to transfer longitudinal loads between the radius and the ulna.9Birkbeck D.P. Failla J.M. Hoshaw S.J. Fyhrie D.P. Schaffler M. The interosseous membrane affects load distribution in the forearm.J Hand Surg Am. 1997; 22: 975-980Abstract Full Text PDF PubMed Scopus (107) Google Scholar When ulnar variance is neutral, the radiocarpal joint absorbs 80% of the axial load transmitted through the wrist, and the remaining 20% is transmitted to the ulna.10Palmer A.K. Werner F.W. Biomechanics of the distal radioulnar joint.Clin Orthop Relat Res. 1984; 187: 26-35PubMed Google Scholar The IOM transfers load from the radius to the ulna as the force travels through the forearm, so that, at the elbow, the radiocapitellar joint is subjected to 60% of the original axial load and the ulnohumeral joint the remaining 40%.11Halls A.A. Travill A. Transmission of pressures across the elbow joint.Anat Rec. 1964; 150: 243-247Crossref PubMed Scopus (172) Google ScholarThe IOM also functions as a longitudinal and a transverse stabilizer of the forearm. After radial head resection (the primary longitudinal stabilizer of the forearm), the central band segment of the IOM was found to contribute 71% to the overall mechanical stiffness of the forearm.12Hotchkiss R.N. An K.N. Sowa D.T. Basta S. Weiland A.J. An anatomic and mechanical study of the interosseous membrane of the forearm: pathomechanics of proximal migration of the radius.J Hand Surg Am. 1989; 14: 256-261Abstract Full Text PDF PubMed Scopus (246) Google Scholar Hotchkiss et al12Hotchkiss R.N. An K.N. Sowa D.T. Basta S. Weiland A.J. An anatomic and mechanical study of the interosseous membrane of the forearm: pathomechanics of proximal migration of the radius.J Hand Surg Am. 1989; 14: 256-261Abstract Full Text PDF PubMed Scopus (246) Google Scholar noted that, after resection of the radial head, the IOM transmits 90% of the axial load through the forearm, thus resisting proximal migration of the radius. The proximal membranous portion of the IOM contributes to the stability of the PRUJ, and the distal segment of the IOM provides stability to the DRUJ, particularly in the 40% of individuals who have a distal oblique bundle.13Gofton W.T. Gordon K.D. Dunning C.E. Johnson J.A. King G.J. Soft-tissue stabilizers of the distal radioulnar joint: an in vitro kinematic study.J Hand Surg Am. 2004; 29: 423-431Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar, 14Arimitsu S. Moritomo H. Kitamura T. et al.The stabilizing effect of the distal interosseous membrane on the distal radioulnar joint in an ulnar shortening procedure: a biomechanical study.J Bone Joint Surg Am. 2011; 93: 2022-2030Crossref PubMed Scopus (43) Google Scholar, 15Poitevin L.A. Anatomy and biomechanics of the interosseous membrane: its importance in the longitudinal stability of the forearm.Hand Clin. 2001; 17 (vii): 97-110PubMed Google Scholar In addition to longitudinal forearm stability, the distal IOM also resists volar and dorsal translation of the distal radius at the DRUJ.16Watanabe H. Berger R.A. Berglund L.J. Zobitz M.E. An K.N. Contribution of the interosseous membrane to distal radioulnar joint constraint.J Hand Surg Am. 2005; 30: 1164-1171Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar Watanabe et al16Watanabe H. Berger R.A. Berglund L.J. Zobitz M.E. An K.N. Contribution of the interosseous membrane to distal radioulnar joint constraint.J Hand Surg Am. 2005; 30: 1164-1171Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar have demonstrated that both TFCC and IOM disruption are required for DRUJ dislocation to occur. The function of the IOM to provide transverse stability was explored by Pfaeffle et al,17Pfaeffle H.J. Fischer K.J. Manson T.T. Tomaino M.M. Woo S.L. Herndon J.H. Role of the forearm interosseous ligament: is it more than just longitudinal load transfer?.J Hand Surg Am. 2000; 25: 683-688Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar who identified transverse force vectors within the IOM that help to pull the radius and ulna together, thus preventing radioulnar splaying.The DRUJ links the radius and the ulna in the distal forearm. It consists of soft tissue stabilizers including the TFCC, the distal IOM, and the pronator quadratus as well as the bony articulation between the radius and the ulna at the sigmoid notch. Of these structures, the TFCC, which includes the dorsal and palmar radioulnar ligaments as well as the ulnocarpal ligaments, is the primary stabilizer of the DRUJ.18Lawler E. Adams B.D. Reconstruction for DRUJ instability.Hand (N Y). 2007; 2: 123-126Crossref PubMed Scopus (36) Google Scholar Consequently, the TFCC is a secondary stabilizer of the forearm unit, and it is responsible for 8% of the mechanical stiffness of the forearm.12Hotchkiss R.N. An K.N. Sowa D.T. Basta S. Weiland A.J. An anatomic and mechanical study of the interosseous membrane of the forearm: pathomechanics of proximal migration of the radius.J Hand Surg Am. 1989; 14: 256-261Abstract Full Text PDF PubMed Scopus (246) Google ScholarMechanism of InjuryTrauma that completely disrupts the forearm unit produces acute longitudinal forearm instability. An Essex-Lopresti injury pattern typically occurs when a fall from a height onto the outstretched hand imparts an axial force that causes a radial head fracture, IOM disruption, and TFCC tear. Galeazzi fractures (radial shaft fracture with associated DRUJ dislocation), Monteggia fractures (ulnar shaft fracture with associated PRUJ dislocation), and isolated DRUJ dislocations are other examples of transverse forearm instability patterns. In contrast to Essex-Lopresti lesions, these injury patterns typically spare the central band of the IOM, and they are also easier to recognize based on injury radiographs. Essex-Lopresti injuries, however, are often more difficult to fully appreciate in the acute setting, but they may lead to longitudinal forearm instability.Pathomechanics of InstabilityForearm instability most frequently occurs following a traumatic axial load through the forearm and an obvious radial head fracture. This radial head fracture may or may not be associated with complete disruption of the IOM and TFCC. Treatment options for radial head fractures include open reduction and internal fixation, excision of the radial head, or radial head replacement. Radial head excision in the setting of a compromised IOM and TFCC can lead to longitudinal radioulnar dissociation due to loss of the primary and secondary forearm stabilizers. Proximal radial migration and relative ulnar lengthening predictably occur, leading to ulnar abutment at the wrist and radiocapitellar impingement.Excision of the radial head without disruption of any other forearm stabilizers can result in up to 7 mm of proximal migration of the radius with axial loading of the forearm.6Rabinowitz R.S. Light T.R. Havey R.M. et al.The role of the interosseous membrane and triangular fibrocartilage complex in forearm stability.J Hand Surg Am. 1994; 19: 385-393Abstract Full Text PDF PubMed Scopus (126) Google Scholar There is little change in the distance that the radius migrates proximally if either the IOM or the TFCC remains intact because the intact soft tissue stabilizers resist this proximal migration. However, if the radial head is excised, and both the TFCC and the central portion of the IOM are injured, further proximal migration of the radius occurs and a complete Essex-Lopresti results.6Rabinowitz R.S. Light T.R. Havey R.M. et al.The role of the interosseous membrane and triangular fibrocartilage complex in forearm stability.J Hand Surg Am. 1994; 19: 385-393Abstract Full Text PDF PubMed Scopus (126) Google Scholar Proximal migration occurs when the radial head is excised and the IOM is disrupted because load cannot be transmitted from the radius to the ulna through the damaged IOM. Tomaino et al19Tomaino M.M. Pfaeffle J. Stabile K. Li Z.M. Reconstruction of the interosseous ligament of the forearm reduces load on the radial head in cadavers.J Hand Surg Br. 2003; 28: 267-270Crossref PubMed Scopus (61) Google Scholar as well as Birkbeck et al9Birkbeck D.P. Failla J.M. Hoshaw S.J. Fyhrie D.P. Schaffler M. The interosseous membrane affects load distribution in the forearm.J Hand Surg Am. 1997; 22: 975-980Abstract Full Text PDF PubMed Scopus (107) Google Scholar demonstrated that, with an intact radial head and a sectioned IOM, load transmission from the radius to the ulna no longer occurred, and the entire load was transmitted along the radius from the radiocarpal joint directly to the radiocapitellar joint. This increased force through the radiocapitellar joint results in abnormal wear patterns, which can subsequently lead to radiocapitellar arthritis, elbow pain, and decreased motion. When the radial head has been excised and the IOM is compromised, all the force is transferred directly from the radiocarpal joint through the radius to the proximal radial stump/capitellar joint. This load transmission combined with the proximal pull of the wrist and finger flexor and extensor tendons, along with the biceps on the radius, generates an axial load along the forearm. These forces lead to proximal radial migration, radiocapitellar impingement, and relative ulnar lengthening along with associated elbow and wrist symptoms.20Hotchkiss R.N. Injuries to the interosseous ligament of the forearm.Hand Clin. 1994; 10: 391-398PubMed Google Scholar For every 1 mm of proximal radial migration, a 10% increase in load across the distal ulna occurs.21Shepard M.F. Markolf K.L. Dunbar A.M. Effects of radial head excision and distal radial shortening on load-sharing in cadaver forearms.J Bone Joint Surg Am. 2001; 83: 92-100PubMed Google Scholar This increased load across the ulnocarpal joint can lead to symptoms of ulnocarpal abutment, including limited forearm rotation, wrist pain, and DRUJ instability.Longitudinal radioulnar dissociation can occur as an acute process with radial head fracture and complete disruption of the IOM and TFCC, but more commonly, the radial head fracture is associated with an incomplete injury to the IOM. If radial head excision is performed in this setting, the remaining fibers of the IOM central band are forced to resist longitudinal forearm forces and prevent proximal migration of the radius. As shown by Skahen et al22Skahen III, J.R. Palmer A.K. Werner F.W. Fortino M.D. The interosseous membrane of the forearm: anatomy and function.J Hand Surg Am. 1997; 22: 981-985Abstract Full Text PDF PubMed Scopus (137) Google Scholar and Hotchkiss et al,12Hotchkiss R.N. An K.N. Sowa D.T. Basta S. Weiland A.J. An anatomic and mechanical study of the interosseous membrane of the forearm: pathomechanics of proximal migration of the radius.J Hand Surg Am. 1989; 14: 256-261Abstract Full Text PDF PubMed Scopus (246) Google Scholar once the radial head is excised, the central band of the IOM becomes responsible for 71% of the longitudinal stiffness of the forearm. This increase in stress across the IOM may lead to attenuation of remaining intact IOM fibers8Skahen III, J.R. Palmer A.K. Werner F.W. Fortino M.D. Reconstruction of the interosseous membrane of the forearm in cadavers.J Hand Surg Am. 1997; 22: 986-994Abstract Full Text PDF PubMed Scopus (92) Google Scholar, 22Skahen III, J.R. Palmer A.K. Werner F.W. Fortino M.D. The interosseous membrane of the forearm: anatomy and function.J Hand Surg Am. 1997; 22: 981-985Abstract Full Text PDF PubMed Scopus (137) Google Scholar and eventual longitudinal forearm instability.DiagnosisHistory and physical examination findingsThe first step in establishing the diagnosis of longitudinal radioulnar dissociation is achieved by obtaining a detailed history and performing a proper physical examination. Patients typically describe a fall on an outstretched hand with the elbow extended, sustaining an acute axial load injury. In the acute setting, pain at the elbow is often due to a radial head fracture, and elbow and forearm motion may be limited secondary to a joint effusion and/or a displaced radial head fracture. Tenderness to palpation at the mid-dorsal forearm, the DRUJ, and/or the fovea heightens suspicion for longitudinal radioulnar dissociation. The DRUJ should also be evaluated for instability in full supination, neutral rotation, and full pronation. The clinician should be aware, however, that these additional physical examination findings may be negative in the acute setting even when an Essex-Lopresti injury has occurred.In subacute and chronic cases, patients may present with a history of a previous radial head fracture and subsequent excision. Chronic wrist pain often develops along with limited wrist and forearm motion, and weakness of grip. A prominent distal ulna is also evident owing to proximal migration of the radius.Imaging—radiographsFor an acute injury, radiographs of the elbow and the wrist are necessary for evaluation. Anteroposterior, lateral, and oblique views of the elbow reveal the degree of displacement and comminution of a radial head fracture. Neutral rotation posteroanterior and lateral views of the wrist joint may demonstrate widening of the DRUJ or positive ulnar variance. If static posteroanterior and lateral wrist views are normal, a grip-loaded pronation posteroanterior view is helpful to demonstrate dynamic ulnar-positive variance. Radiographs of the contralateral uninjured wrist joint are obtained for comparison. Essex-Lopresti lesions may not be evident on these initial radiographs.23Sowa D.T. Hotchkiss R.N. Weiland A.J. Symptomatic proximal translation of the radius following radial head resection.Clin Orthop Relat Res. 1995; 317: 106-113PubMed Google Scholar, 24Rodriguez-Martin J. Pretell-Mazzini J. Vidal-Bujanda C. Unusual pattern of Essex-Lopresti injury with negative plain radiographs of the wrist: a case report and literature review.Hand Surg. 2010; 15: 41-45Crossref PubMed Scopus (12) Google Scholar but repeat radiographs may detect the injury pattern. An additional set of radiographs should be performed if a patient's follow-up examination is concerning for longitudinal radioulnar dissociation.25Helmerhorst G.T. Ring D. Subtle Essex-Lopresti lesions: report of 2 cases.J Hand Surg Am. 2009; 34: 436-438Abstract Full Text Full Text PDF PubMed Scopus (15) Google ScholarFor delayed presentation or chronic wrist pain associated with a previous radial head fracture, the same sets of radiographs are obtained. The x-rays should be scrutinized for positive ulnar variance and cystic or sclerotic changes in the proximal ulnar aspect of the lunate and/or radial aspect of the triquetrum secondary to ulnar impaction. When available, these images may be compared with those obtained at the time of injury. Wrist magnetic resonance imaging (MRI) can also be useful to further assess for evidence of ulnar impaction and TFCC tearing.Advanced imaging—MRI and ultrasoundA thorough history, physical examination, and appropriate radiographic studies are not always diagnostic of acute Essex-Lopresti lesions. The concern for underrecognition of this injury pattern has led to considerable research to improve diagnosis of longitudinal radioulnar dissociations. Multiple studies have examined the utility of MRI and ultrasound to improve the diagnosis of IOM disruptions and TFCC injuries associated with radial head fractures.MRI and ultrasound have emerged as useful tools for the evaluation of ruptures of the IOM. In a study evaluating the effectiveness of MRI in diagnosing IOM injuries in cadavers and patients, Starch and Dabenzies26Starch D.W. Dabezies E.J. Magnetic resonance imaging of the interosseous membrane of the forearm.J Bone Joint Surg Am. 2001; 83: 235-238Crossref PubMed Scopus (106) Google Scholar illustrated excellent results using T2-weighted fast spin-echo fat-suppressed images. Fester et al27Fester E.W. Murray P.M. Sanders T.G. Ingari J.V. Leyendecker J. Leis H.L. The efficacy of magnetic resonance imaging and ultrasound in detecting disruptions of the forearm interosseous membrane: a cadaver study.J Hand Surg Am. 2002; 27: 418-424Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar used a cadaver model to establish the sensitivity and specificity of MRI to diagnose central band transections of the IOM. The mean sensitivity was 93%, specificity was 100%, and the overall accuracy of using MRI to diagnose an IOM central third disruption was 96%. They also confirmed that the central band disruption was most easily identified as wavy, bowed, and discontinuous ligament fibers seen on T2-weighted axial cuts. McGinley et al28McGinley J.C. Roach N. Gaughan J.P. Kozin S.H. Forearm interosseous membrane imaging and anatomy.Skeletal Radiol. 2004; 33: 561-568Crossref PubMed Scopus (20) Google Scholar compared use of MRI versus laser micrometry for evaluation of the IOM anatomy and found that there was no significant difference between the two methods of evaluation (P = .75). In another study, McGinley et al29McGinley J.C. Roach N. Hopgood B.C. Limmer K. Kozin S.H. Forearm interosseous membrane trauma: MRI diagnostic criteria and injury patterns.Skeletal Radiol. 2006; 35: 275-281Crossref PubMed Scopus (33) Google Scholar evaluated MRI as a tool for accurate diagnosis of traumatic IOM injuries induced in a cadaver model. In this study, diagnosis by MRI had a sensitivity of 8
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