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Correlation between radiological assessment of acute ankle fractures and syndesmotic injury on MRI.

Hermans JJ, Wentink N, Beumer A, Hop WC, Heijboer MP, Moonen AF, Ginai AZ - Skeletal Radiol. (2011)

Bottom Line: When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed.Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling.TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. jjhermans@gmail.com

ABSTRACT

Objective: Owing to the shortcomings of clinical examination and radiographs, injury to the syndesmotic ligaments is often misdiagnosed. When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed. Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling. We evaluated three fracture classification methods and radiographic measurements with respect to syndesmotic injury.

Materials and methods: Prospectively the radiographs of 51 consecutive ankle fractures were classified according to Weber, AO-Müller, and Lauge-Hansen. Both the fracture type and additional measurements of the tibiofibular clear space (TFCS), tibiofibular overlap (TFO), medial clear space (MCS), and superior clear space (SCS) were used to assess syndesmotic injury. MRI, as standard of reference, was performed to evaluate the integrity of the distal tibiofibular syndesmosis. The sensitivity and specificity for detection of syndesmotic injury with radiography were compared to MRI.

Results: The Weber and AO-Müller fracture classification system, in combination with additional measurements, detected syndesmotic injury with a sensitivity of 47% and a specificity of 100%, and Lauge-Hansen with both a sensitivity and a specificity of 92%. TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

Conclusion: Syndesmotic injury as predicted by the Lauge-Hansen fracture classification correlated well with MRI findings. With MRI the extent of syndesmotic injury and therefore fracture stage can be assessed more accurately compared to radiographs.

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AP (a) and lateral (b) radiographs show a distal fibula fracture (1) at the level of the syndesmosis, running obliquely from anteroinferior to posterosuperior, characteristic of a supination-external rotation trauma. Measurements are normal. This fracture is classified as Weber type B, AO-Müller type B1.1, and Lauge-Hansen SE2. Coronal (c) and 45° oblique (d) proton-density-weighted MR images demonstrate the fibula fracture (1), and a normal deep (2) and superficial (3) deltoid ligament. The ATIFL is ruptured (4), whereas the intact PTIFL (5) is attached to an avulsion fracture of the posterolateral malleolus (6). This is therefore a Weber type B fracture with normal measurements but with anterior as well as posterior syndesmotic injury. According to Lauge-Hansen, this is an SE3 fracture
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Fig6: AP (a) and lateral (b) radiographs show a distal fibula fracture (1) at the level of the syndesmosis, running obliquely from anteroinferior to posterosuperior, characteristic of a supination-external rotation trauma. Measurements are normal. This fracture is classified as Weber type B, AO-Müller type B1.1, and Lauge-Hansen SE2. Coronal (c) and 45° oblique (d) proton-density-weighted MR images demonstrate the fibula fracture (1), and a normal deep (2) and superficial (3) deltoid ligament. The ATIFL is ruptured (4), whereas the intact PTIFL (5) is attached to an avulsion fracture of the posterolateral malleolus (6). This is therefore a Weber type B fracture with normal measurements but with anterior as well as posterior syndesmotic injury. According to Lauge-Hansen, this is an SE3 fracture

Mentions: In six other cases of underestimated syndesmotic injury, LH predicted only anterior syndesmotic injury, whereas MRI showed also posterior injury. Anterior syndesmotic injury consisted of a ruptured ATFIL in four and an anterior fibular avulsion fracture in two patients. Posterior syndesmotic injury involved five patients with an intact PTIFL attached to an avulsed fragment of the posterior malleolus, which was not visible on the radiographs, and one patient with a ruptured posterior tibiofibular ligament (Fig. 6). In two patients the superficial deltoid ligament was partially or completely ruptured. With these findings on MRI, the fracture would change from SE2 into SE3 in three cases, from SE2 into SE4 in two cases, and from unclassifiable SE1/PE1 into PA2 in one case. For therapeutic management it is important to know whether a fracture is stable or unstable. An unstable fracture should be treated with an open reduction and internal fixation (ORIF) and, if necessary, syndesmotic stability should be regained with a setscrew. In two patients with an underestimated SE4 fracture, ORIF was performed without fixation of the syndesmosis with a setscrew, although on MRI the superficial ligament was partially or completely ruptured, and the deep deltoid ligament was intact in both. The measurements deviated only in one case. It is likely that the deep deltoid ligament prevents a lateral shift of the talus when the fibula is pulled laterally with the hook test [29], whereas the superficial deltoid ligament gives restraint to a valgus position of the talus.Fig. 6


Correlation between radiological assessment of acute ankle fractures and syndesmotic injury on MRI.

Hermans JJ, Wentink N, Beumer A, Hop WC, Heijboer MP, Moonen AF, Ginai AZ - Skeletal Radiol. (2011)

AP (a) and lateral (b) radiographs show a distal fibula fracture (1) at the level of the syndesmosis, running obliquely from anteroinferior to posterosuperior, characteristic of a supination-external rotation trauma. Measurements are normal. This fracture is classified as Weber type B, AO-Müller type B1.1, and Lauge-Hansen SE2. Coronal (c) and 45° oblique (d) proton-density-weighted MR images demonstrate the fibula fracture (1), and a normal deep (2) and superficial (3) deltoid ligament. The ATIFL is ruptured (4), whereas the intact PTIFL (5) is attached to an avulsion fracture of the posterolateral malleolus (6). This is therefore a Weber type B fracture with normal measurements but with anterior as well as posterior syndesmotic injury. According to Lauge-Hansen, this is an SE3 fracture
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Related In: Results  -  Collection

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Fig6: AP (a) and lateral (b) radiographs show a distal fibula fracture (1) at the level of the syndesmosis, running obliquely from anteroinferior to posterosuperior, characteristic of a supination-external rotation trauma. Measurements are normal. This fracture is classified as Weber type B, AO-Müller type B1.1, and Lauge-Hansen SE2. Coronal (c) and 45° oblique (d) proton-density-weighted MR images demonstrate the fibula fracture (1), and a normal deep (2) and superficial (3) deltoid ligament. The ATIFL is ruptured (4), whereas the intact PTIFL (5) is attached to an avulsion fracture of the posterolateral malleolus (6). This is therefore a Weber type B fracture with normal measurements but with anterior as well as posterior syndesmotic injury. According to Lauge-Hansen, this is an SE3 fracture
Mentions: In six other cases of underestimated syndesmotic injury, LH predicted only anterior syndesmotic injury, whereas MRI showed also posterior injury. Anterior syndesmotic injury consisted of a ruptured ATFIL in four and an anterior fibular avulsion fracture in two patients. Posterior syndesmotic injury involved five patients with an intact PTIFL attached to an avulsed fragment of the posterior malleolus, which was not visible on the radiographs, and one patient with a ruptured posterior tibiofibular ligament (Fig. 6). In two patients the superficial deltoid ligament was partially or completely ruptured. With these findings on MRI, the fracture would change from SE2 into SE3 in three cases, from SE2 into SE4 in two cases, and from unclassifiable SE1/PE1 into PA2 in one case. For therapeutic management it is important to know whether a fracture is stable or unstable. An unstable fracture should be treated with an open reduction and internal fixation (ORIF) and, if necessary, syndesmotic stability should be regained with a setscrew. In two patients with an underestimated SE4 fracture, ORIF was performed without fixation of the syndesmosis with a setscrew, although on MRI the superficial ligament was partially or completely ruptured, and the deep deltoid ligament was intact in both. The measurements deviated only in one case. It is likely that the deep deltoid ligament prevents a lateral shift of the talus when the fibula is pulled laterally with the hook test [29], whereas the superficial deltoid ligament gives restraint to a valgus position of the talus.Fig. 6

Bottom Line: When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed.Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling.TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. jjhermans@gmail.com

ABSTRACT

Objective: Owing to the shortcomings of clinical examination and radiographs, injury to the syndesmotic ligaments is often misdiagnosed. When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed. Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling. We evaluated three fracture classification methods and radiographic measurements with respect to syndesmotic injury.

Materials and methods: Prospectively the radiographs of 51 consecutive ankle fractures were classified according to Weber, AO-Müller, and Lauge-Hansen. Both the fracture type and additional measurements of the tibiofibular clear space (TFCS), tibiofibular overlap (TFO), medial clear space (MCS), and superior clear space (SCS) were used to assess syndesmotic injury. MRI, as standard of reference, was performed to evaluate the integrity of the distal tibiofibular syndesmosis. The sensitivity and specificity for detection of syndesmotic injury with radiography were compared to MRI.

Results: The Weber and AO-Müller fracture classification system, in combination with additional measurements, detected syndesmotic injury with a sensitivity of 47% and a specificity of 100%, and Lauge-Hansen with both a sensitivity and a specificity of 92%. TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

Conclusion: Syndesmotic injury as predicted by the Lauge-Hansen fracture classification correlated well with MRI findings. With MRI the extent of syndesmotic injury and therefore fracture stage can be assessed more accurately compared to radiographs.

Show MeSH
Related in: MedlinePlus