Abstract
IntroductionThe aim of the present study was to analyze the injury pattern and thus the dislocation mechanism after simple elbow dislocation using radiographs and magnetic resonance imaging (MRI) data sets.Materials and methodsThe MRI data sets of 64 patients with a mean age of 44 years (18–77 years) were analyzed retrospectively. The inclusion criteria for the study were (1) radiograph with confirmed simple elbow dislocation, (2) low-energy trauma, (3) MRI of the affected elbow ≤ 3 weeks after trauma. The dislocation direction was determined using radiographs. The integrity of the lateral collateral ligament complex (LCLC), common extensor origin (CEO), anterior capsule (AC), medial collateral ligament (MCL), and common flexor origin (CFO) as well as the joint congruity were assessed based on MRI.Results34 patients (53%) had a posterolateral, 26 patients (41%) a posterior, and 4 patients (6%) a posteromedial dislocation. LCLC and AC were affected in 64 out of 64 patients (100%). MCL was affected in 58 patients (91%). CEO were affected in 25 patients (39%) and the CFO in 20 patients (31%). In 11 patients (17%) the injury pattern was more pronounced medially than laterally (MCL, CFO, LCLC), with 2 of these patients exhibiting only a partial LCLC tear. All cases with joint incongruency (n = 12, 19%) showed CEO and/or CFO involvement.ConclusionsSimple elbow dislocation leads to a very heterogeneous spectrum of soft tissue injury pattern. A small proportion of patients showed medially pronounced injury patterns. These findings strongly indicate existence of a “reversed Horii circle” with an underlying valgus mechanism (medial force induction) originating and continuing from medial to anterior.
Highlights
The aim of the present study was to analyze the injury pattern and the dislocation mechanism after simple elbow dislocation using radiographs and magnetic resonance imaging (MRI) data sets
All consecutive patients were included in the period from March 2010 to November 2018 as long as they met the following inclusion criteria: (1) minimum age of 18 years, (2) ligamentous elbow dislocation, (3) low-energy trauma according to the definition of Mackey et al [13], (4) radiologically verified elbow dislocation, and (5) magnetic resonance imaging (MRI) of the affected elbow up to a maximum of 21 days post-trauma
Analysis of the dislocation direction revealed that there was a posterolateral dislocation in 34 patients (53%), a posterior dislocation in 26 patients (41%), and a posteromedial dislocation in 4 patients (6%)
Summary
The aim of the present study was to analyze the injury pattern and the dislocation mechanism after simple elbow dislocation using radiographs and magnetic resonance imaging (MRI) data sets. As early as 1992, O’Driscoll et al studied the accident process in detail: according to this, a supination moment coupled with valgus stress results in rupture of the lateral collateral ligament complex and the posterolateral parts of the capsule and in dislocation [15]. Scheiber et al evaluated video sequences of documented elbow dislocations and concluded that valgus stress on the fully extended elbow caused the dislocation in the majority of cases [23] This would suggest that in these cases it primarily leads to a rupture of the medial ligamentous apparatus. The authors reported that 36% of the patients had a higher degree of joint gap widening on the medial side with stable conditions on the lateral side
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