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Table of Contents
CASE REPORT
Year : 2021  |  Volume : 18  |  Issue : 2  |  Page : 135-137

Imaging in chronic posterior dislocation of the elbow: A rare entity


Department of Radiology, Holy Family Hospital, Thodupuzha, Kerala, India

Date of Submission12-Nov-2020
Date of Acceptance21-Jan-2021
Date of Web Publication02-Mar-2021

Correspondence Address:
Reddy Ravikanth
Department of Radiology, Holy Family Hospital, Thodupuzha - 685 605, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/am.am_5_20

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  Abstract 


The elbow is a complex joint, and traumatic dislocation of the elbow is the second most common major joint dislocation in adults more commonly occurring in athletes. Initial investigation of the suspected elbow dislocation includes radiographs in anteroposterior, lateral and oblique views. This case report describes chronic posterior dislocation in a 58-year-old woman and also describes the magnetic resonance imaging anatomy of the elbow joint. Timely intervention can alleviate symptoms and can prevent deformity and neurovascular sequelae.

Keywords: Chronic posterior dislocation, elbow joint, Horii circle, magnetic resonance imaging, neurovascular complications


How to cite this article:
Ravikanth R. Imaging in chronic posterior dislocation of the elbow: A rare entity. Apollo Med 2021;18:135-7

How to cite this URL:
Ravikanth R. Imaging in chronic posterior dislocation of the elbow: A rare entity. Apollo Med [serial online] 2021 [cited 2021 Jun 21];18:135-7. Available from: https://www.apollomedicine.org/text.asp?2021/18/2/135/310643


  Introduction Top


The elbow is a complex joint, and traumatic dislocation of the elbow is the second most common major joint dislocation in adults more commonly occurring in athletes.[1] Initial investigation of the suspected elbow dislocation includes radiographs in anteroposterior, lateral and oblique views. Most of the cases are managed nonoperatively without requiring further investigation. However, a small proportion of patients require surgical intervention to prevent delayed complications and persistent instability.[2]

This article describes the anatomy of the elbow joint, explains the mechanism, and describes the imaging findings of traumatic posterior elbow dislocation. Magnetic resonance imaging (MRI) with its superior resolution helps in identifying the location and severity of ligamentous and bony injuries after elbow dislocations, thereby providing accurate preoperative assessment and improving the treatment outcome.

Magnetic resonance imaging of the elbow joint

MRI of the elbow joint should be performed in all three planes. The sequence varies by institution but should include T1-weighted and fat-saturated (fat sat) T2-weighted/proton density (PD)-weighted sequences. T1-weighted images are used for looking anatomy and marrow with arthrography useful in certain cases. T2-weighted/PD fat sat images are useful in identifying the pathology in most of the cases. Gradient echo sequences can be added to assess cartilage and for suspicion of loose bodies or hemosiderin deposition. Similarly, routine of contrast administration is not necessary.

Magnetic resonance anatomy of elbow joint

The elbow is a complex joint comprising bony articulation among the humerus, radius, and ulna, allowing both stability and a combination of movements. The joint capsule is thickened medially and laterally to form the collateral ligament complexes.

The medial collateral ligament (MCL) complex that arises extends from the medial epicondyle of the humerus to the sublime tubercle of the ulna and consists of anterior, posterior, and transverse bundles. The anterior bundle is further divided into anterior and posterior bands. The lateral collateral ligament complex consists of four components: annular ligament, which courses around the radial head and attaches to sigmoid notch of ulna; the radial collateral ligament (RCL) extending from the lateral epicondyle to the annular ligament; the lateral ulnar collateral ligament (LUCL), which runs posteriorly from the lateral epicondyle to the supinator crest of the ulna; and the functionally insignificant and variably present accessory collateral ligament.[3],[4]

The functional stability is provided by three primary and four secondary components. The ulnohumeral articulation, the anterior bundle of the MCL, and the LUCL are the primary stabilizing structures. Secondary stabilization is provided by the radiocapitellar articulation, the common flexor tendon, the common extensor tendon, and the joint capsule.[5]

Mechanism of elbow dislocation

O'Driscoll et al. proposed that elbows dislocate in three stages progressing from posterolateral rotatory instability to dislocation from lateral to the medial side termed the “Horii circle.”[6] Stage 1 is complete disruption of the LUCL and partial or complete disruption of rest of the lateral collateral ligament complex, resulting in posterolateral rotatory subluxation. Stage 2 is the disruption of the anterior capsule and incomplete elbow dislocation in a posterolateral direction, resulting in coronoid process perched on the humeral trochlea. Stage 3 includes two stages. First is disruption of the MCL except for the anterior bundle, which acts as a pivot around which the elbow joint dislocates in a posterior direction followed by complete disruption of the MCL complex.

Recently, Schwab et al.[7] postulated that the initial step in elbow dislocation is rupture or avulsion of the MCL or fracture of the medial epicondyle with MCL attached. This theory is supported by Schreiber et al.,[8] who reported that the disruption progresses from medial to the lateral side of the elbow joint.


  Case Report Top


A right-handed dominant 58 year-old woman presented to the outpatient department complaining limitation of range of motion and pain on the right elbow, 7 weeks after an isolated right elbow dislocation following a fall. On the date of injury, she had undergone closed reduction of the elbow dislocation at an outside facility and was on irregular follow-up in that hospital. She had only mild pain and discomfort around elbow, and hence, she waited for >6 weeks before consulting me. Physical examination revealed mild swelling of the elbow with 45° fixed flexion deformity; further flexion was possible up to 100°. The extremity was neurovascularly intact. Radiographs obtained showed unreduced medial dislocation of the elbow [Figure 1]. Computed tomography and MRI were also done for further evaluation of the injury [Figure 2] and [Figure 3]. After discussion of the treatment options, the patient agreed to proceed with surgical intervention. She underwent open reduction of the chronic unreduced medial elbow dislocation with reconstruction of the LUCL.
Figure 1: Anteroposterior and lateral radiographs demonstrating chronic medial dislocation of the right elbow

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Figure 2: Serial magnetic resonance images demonstrating chronic unreduced medial elbow dislocation with disruption of the lateral ulnar collateral ligament

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Figure 3: Reformatted three-dimensional-reconstruction of the right elbow joint demonstrating complete disruption of ulnohumeral articulation resulting in medial elbow dislocation

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  Discussion Top


Chronic unreduced elbow dislocations are rare injuries.[9] Simple medial dislocations of the elbow are also rare injuries and are at risk for early instability.[10] Chronic unreduced medial dislocation of the elbow in adult is extremely rare.[11] Normally, the medial lip of the trochlea of humerus rests on the inferior medial trochlear notch of ulna; in chronic medial dislocation (chronic locked medial dislocation) of the elbow as seen in this case [Figure 1], the medial lip of the trochlea articulates with the potential space in the superior radioulnar joint with anteroposterior stability offered by annular ligaments. This might be the reason for the relative stability seen in this case of chronic medial dislocation of the elbow, which also explains the fewer symptoms and signs that the patient had following dislocation and the delayed arrival of the patient in our hospital for treatment.


  Conclusion Top


Chronic unreduced medial dislocation of the elbow is a rare injury. These patients may neglect their injury due to the relatively fewer symptoms and signs. Timely intervention can alleviate symptoms and can prevent deformity and neurovascular sequelae.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kuhn MA, Ross G. Acute elbow dislocations. Orthop Clin North Am 2008;39:155-61, v.  Back to cited text no. 1
    
2.
Modi CS, Wasserstein D, Mayne IP, Henry PD, Mahomed N, Veillette CJ. The frequency and risk factors for subsequent surgery after a simple elbow dislocation. Injury 2015;46:1156-60.  Back to cited text no. 2
    
3.
Alcid JG, Ahmad CS, Lee TQ. Elbow anatomy and structural biomechanics. Clin Sports Med 2004;23:503-17, vii.  Back to cited text no. 3
    
4.
Mallisee TA, Boynton MD, Erickson SJ, Daniels DL. Normal MR imaging anatomy of the elbow. Magn Reson Imaging Clin N Am 1997;5:451-79.  Back to cited text no. 4
    
5.
de Haan J, Schep NW, Eygendaal D, Kleinrensink GJ, Tuinebreijer WE, den Hartog D. Stability of the elbow joint: Relevant anatomy and clinical implications of in vitro biomechanical studies. Open Orthop J 2011;5:168-76.  Back to cited text no. 5
    
6.
O'Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF. The unstable elbow. Instr Course Lect 2001;50:89-102.  Back to cited text no. 6
    
7.
Schwab GH, Bennett JB, Woods GW, Tullos HS. Biomechanics of elbow instability: the role of the medial collateral ligament. Clin Orthop Relat Res 1980:42-52.  Back to cited text no. 7
    
8.
Schreiber JJ, Warren RF, Hotchkiss RN, Daluiski A. An online video investigation into the mechanism of elbow dislocation. J Hand Surg Am 2013;38:488-94.  Back to cited text no. 8
    
9.
Rubino LJ, Herbenick MA, Finnan RP, Anloague PA. Chronic elbow dislocation treated with open reduction and lateral ulnar collateral ligament reconstruction. Am J Orthop (Belle Mead NJ) 2009;38:E98-100.  Back to cited text no. 9
    
10.
Jockel CR, Katolik LI, Zelouf DS. Simple medial elbow dislocations: A rare injury at risk for early instability. J Hand Surg Am 2013;38:1768-73.  Back to cited text no. 10
    
11.
Ohno Y, Shimizu K, Ohnishi K. Surgically treated chronic unreduced medial dislocation of the elbow in a 70-year-old man: A case report. J Shoulder Elbow Surg 2005;14:549-53.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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