Monteggia Fracture dislocation
Introduction
Fracture of Ulna shaft with dislocation of proximal radioulnar joint is called as monteggia # dislocation. First described by Giovanni Battista Monteggia of Milan. Bado later classified them according to the direction of radial head displacement in relation to capitullum. He also described similar variants of this lesion which are called Monteggia Equivalents. It is commonly seen in children who fall on outstreached hand or sustain a direct blow to the back of forearm.
Letts further subclassified them in 5 subtypes as seen in pediatric age group.
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| Bado classification |
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Monteggia equivalents are further subclassified based on direction of radial head.
Type I equivalents is anterior radial head dislocation without ulna # ex: Pulled elbow, radial head dislocation with plastic deformation of ulna, radial head dislocation associated with radial shaft # proximal to ulna #, radial head dislocation with radial neck and ulna shaft #, radial head dislocation with ulna shaft comminuted #. All these must have anterior dislocation of radial head.
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| Monteggia I equivalents |
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Monteggia Type II equivalents
ex: Radial neck or physeal fractures with posterior displacement, posterior dislocation of elbow
Monteggia Type III / IV equivalents
Bado did not have in his original series these cases but were added up later based on case reports. They include Supracondylar humerus # or lateral condyle # with associated both bones forearm fracture.
Letts further added 2 subgoups to monteggia fractures in children which include plastic deformation of ulna and ulna greenstick #
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| Plastic deformation and ulna grrenstick with radial head dislocation |
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Diagnosis
Clinical suspicion with Full length forearm xrays are key. A line drawn along the proximal radial shaft must pass through the capitullum in any degree of elbow flexion ie radiocapitullar line.
In true lateral view dorsal ulna must form a straight line, if any gap is noted then plastic deformation is present.
Management
Aim of any intervention is to achieve normal ulnar length and correct any angulation with reduction of radial head. It can be achieved by manipulation by reversing the deformity. If stable after reduction can be managed by cast without surgery, in which case repeat weekly Xrays are necessary for followup. Oblique fractures may need either percutaneous fixation or plating for stability. When dealing with neglected monteggia ulnar osteotomy and internal fixation for reversing the deformity with open reduction of radial head are unavoidable. Early neglected monteggia can also be manged by ulna osteotomy and distraction with external fixator. If radial head reduction is unstable it needs annular ligament reconstruction.
Case examples
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| Plastic bowing of ulna with anterior dislocation radial head |
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| 7yrs old boy Akhil with prominence in left elbow due to neglected Monteggia # |
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| Akhil' LAT Xray on day of injury which was missed by treating surgeon | | | | | |
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| Akhil's LAT Xray forearm on day of injury |
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| Akhil's LAT xray forearm after 3 months : note the # union but radial head dislocated | |
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| Akhil's AP xray forearm 3 months post injury |
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| Extension osteotomy for ulna stabilized with 1/3rd tubular plate and open reduction of radial head(below retractor, interval between ECU and anconeus), Forearm fascia prepared for annular ligament reconstruction( in forceps) |
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| Extension osteotomy ulna with dorsal opening( forceps) and volar greenstick |
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| Post op immediate LAT Xray: Radial head reduced with ulnar extn osteotomy |
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| Post op AP xray with radila head reuced and ulnar osteotomy fixed with 1/3rd tubular plate |
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| Another example of a monteggia fracture dislocation in a 15years old girl |
