title: Stability assessment of the ankle mortise in supination-external rotation-type ankle fractures: lack of additional diagnostic value of MRI.
abstract: BACKGROUND
  This prospective diagnostic study assessed the utility of MRI (magnetic resonance imaging) findings for the deep aspect of the deltoid ligament in evaluating the stability of the ankle mortise in patients who have an SER (supination-external rotation)-type lateral malleolar fracture with no widening of the medial clear space.
  
  
  METHODS
  Sixty-one patients with a unilateral lateral malleolar fracture resulting from an SER mechanism were enrolled. Two surgeons assessed the stability of the ankle mortise with use of an external-rotation stress test. The anterior and posterior parts of the deep deltoid ligament were investigated with 3.0-T MRI and were graded (as normal, edematous, partial tear, or complete tear) by two musculoskeletal radiologists. The medial clear space was measured and compared with the MRI findings for the deep deltoid ligament in stable and unstable injuries. Interobserver reliability was calculated for both external-rotation stress testing and MRI assessment.
  
  
  RESULTS
  Thirty-three patients had a medial clear space of ≥ 5 mm in the external-rotation stress test. According to MRI, all of these patients had an injury involving the deep deltoid ligament (an edematous ligament in five, a partial tear in twenty-six, and a total tear in two). Twenty-eight patients had a medial clear space of <5 mm, and MRI indicated a deep deltoid ligament injury in all of these patients as well (an edematous ligament in nine and a partial tear in nineteen). The medial clear space increased according to the severity of the deep deltoid ligament injury as indicated by MRI (p < 0.001). The interobserver agreement of the external-rotation stress test was excellent (94% agreement; kappa = 0.87), whereas the interobserver reliability of the MRI assessments by the two musculoskeletal radiologists was fair to moderate (72% agreement for the posterior part of the deep deltoid ligament and 56% for the anterior part; kappa = 0.46 and 0.22, respectively).
  
  
  CONCLUSIONS
  On the basis of the study results, we do not recommend the use of MRI when choosing between operative and nonoperative treatment of an SER-type ankle fracture.
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Simo
authors.initials: S
authors.lastname: Nortunen
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Sannamari
authors.initials: S
authors.lastname: Lepojärvi
authors.affiliation: Omasairaala, Helsinki, Puutarhurinkuja 2, FI 00300 Helsinki, Finland. E-mail address: olli.savola@omasairaala.fi.
authors.forename: Olli
authors.initials: O
authors.lastname: Savola
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Niinimäki
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Pasi
authors.initials: P
authors.lastname: Ohtonen
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Tapio
authors.initials: T
authors.lastname: Flinkkilä
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Iikka
authors.initials: I
authors.lastname: Lantto
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Tero
authors.initials: T
authors.lastname: Kortekangas
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery (S.N., T.F., I.L., T.K., and H.P), Department of Diagnostic Radiology (S.L. and J.N.), and Department of Anesthesiology and Surgery (P.O.), Oulu University Hospital, PL 21, Kajaanintie 50, FI 90029 OYS, Oulu, Finland. E-mail address for S. Nortunen: simo.nortunen@ppshp.fi. E-mail address for S. Lepojärvi: sannamari.lepojarvi@ppshp.fi. E-mail address for J. Niinimäki: jaakko.niinimaki@ppshp.fi. E-mail address: pasi.ohtonen@oulu.fi. E-mail address for T. Flinkkilä: tapio.flinkkila@ppshp.fi. E-mail address for I. Lantto: iikka.lantto@ppshp.fi. E-mail address for T. Kortekangas: tero.kortekangas@ppshp.fi. E-mail address for H. Pakarinen: harri.pakarinen@ppshp.fi.
authors.forename: Harri
authors.initials: H
authors.lastname: Pakarinen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064386:Ankle Fractures / Q000150:complications* / Q000503:physiopathology; D000843:Ankle Joint / Q000503:physiopathology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D016059:Range of Motion, Articular; D012399:Rotation; D013484:Supination; D055815:Young Adult