Published online Jan 25, 2019.
https://doi.org/10.12671/jkfs.2019.32.1.61
New Injury Mechanism and Treatment Algorithm of Posterior Elbow Dislocation
Abstract
Although the concept of a single elbow dislocation mechanism, in which all dislocations start from the lateral side of the elbow joint and progress to the medial side, has never been able to explain the various conflicting experimental and clinical observations thus far, new studies and proposals for a valid mechanism have not been reported. The new proposal for posteromedial and posterolateral dislocation of the elbow joint according to the authors' study and the new treatment algorithm based on this new study can explain the various clinical and experimental results that have been difficult to explain, and provide a reasonable approach to the treatment of elbow dislocations.
Fig. 1
(A, B) Simple anteroposterior and lateral radiographs of posterolateral dislocation of the elbow joint. (C) On the fat-suppressed T2-weighted coronal view of the magnetic resonance imaging scan, there are distractive injury patterns of the ulnar collateral ligament and flexor-pronator teres muscles caused by the valgus force applied medially (solid arrow) and stripping injury pattern of the lateral collateral ligament complex caused by the forearm external rotational force (dotted arrow) appearing ‘peeled-off’ from the lateral epicondyle and located near the original attachment site. (D) Lateral bony contusion seen on the posterior capitellum and radial head (solid arrows) on the fat-suppressed T2-weighted sagittal view.
Fig. 2
(A, B) Simple anteroposterior and lateral radiographs of posteromedial dislocation of the elbow joint. (C) On the T1-weighted coronal view of magnetic resonance imaging (MRI) scan, there is a distractive injury pattern of the lateral collateral ligament complex caused by the varus force and migrated distally from the original attachment site of the lateral epicondyle (solid arrow). (D) On the T2-weighted fat suppressed axial view of the MRI scan, there is medial bony contusion on the posterior trochlea (dotted arrow) and proximal ulna (solid arrow).
Fig. 3
Sequential scenario of the most common posterolateral dislocation of the elbow joint. (A) The axial force applied along the forearm during the initial injury converts to a valgus force at the medial side due to the cubitus valgus and causes distractive injury of the ulnar collateral ligament and flexor-pronator teres muscles. By the ongoing valgus force, the coronoid process is disengaged from the trochlear notch and the forearm displaces laterally at the first step. (B) Accompanying forearm external rotation displaces the radial head posterior to the posterior capitellum and causes abutment between the radial ahead and the posterior capitellum, which leads to a lateral bony contusion. (C) Finally, the posterolateral dislocation of the elbow joint develops by the continuously applied axial force.
Fig. 4
Sequential scenario of the rare posteromedial dislocation of the elbow joint. (A) The axial force applied along the forearm during the initial injury converts to a varus force at the lateral side, which is rare due to the common cubitus valgus characteristics and more commonly seen in less valgus carrying angle, and causes the distractive injury of the lateral collateral ligament complex and extensor muscles. By the ongoing varus force, the coronoid process is disengaged from the trochlear notch and the forearm displaces medially at the first step. (B) Accompanying forearm external rotation displaces the radial head posterior to the posterior capitellum without impaction and causes abutment between the proximal ulna and the posteromedial capitellum, leading to the medial bony contusion. (C) Finally the posteromedial dislocation of the elbow joint develops by the continuously applied axial force.
Fig. 5
Treatment algorithm for the unstable posterolateral (PL) dislocation of the elbow joint. MRI: magnetic resonance imaging, UCL: ulnar collateral ligament, F-PT: flexor-pronator teres, LCLC: lateral collateral ligament complex, ROM: range of motion.
Fig. 6
Treatment algorithm for the posteromedial (PM) dislocation of the elbow joint. LCLC: lateral collateral ligament complex, ROM: range of motion, UCL: ulnar collateral ligament.
Financial support:None.
Conflict of interests:None.
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