Acute severe valgus instability without elbow dislocation

Dual Bracing for Ulnar Collateral Ligament Injuries Restores Native Valgus Laxity and Native Medial Joint Gapping of the Elbow

Background

Despite growing evidence on the role of the posterior ulnar collateral ligament (pUCL) in elbow stability, current ligament bracing techniques are mainly focused on the anterior ulnar collateral ligament (aUCL). A dual-bracing technique combines the repair of the pUCL and aUCL with a suture augmentation of both bundles.

Purpose

To biomechanically assess a dual-bracing approach addressing aUCL and pUCL for humeral-sided complete UCL lesions to restore medial elbow laxity without overconstraining.

Study Design

Controlled laboratory study.

Methods

A total of 21 unpaired human elbows (11 right, 10 left; 57.19 ± 11.7 years) were randomized into 3 groups to compare dual bracing with aUCL suture augmentation and aUCL graft reconstruction. Laxity testing was performed with 25 N applied 12 cm distal to the elbow joint for 30 seconds at randomized flexion angles (0°, 30°, 60°, 90°, and 120°) for the native condition and then for each surgical technique. A calibrated motion capture system was used for assessment, allowing the 3-dimensional displacement during the complete valgus stress cycle between the optical trackers to be quantified as joint gap and laxity. The repaired constructs were then cyclically tested through a materials testing machine starting with 20 N for 200 cycles at a rate of 0.5 Hz. The load was increased stepwise by 10 N for 200 cycles until displacement reached 5.0 mm or complete failure occurred.

Results

Dual bracing and aUCL bracing resulted in significantly (P = .045) less joint gapping at 120° of flexion compared with aUCL reconstruction. No significant differences in valgus laxity were found among the surgical techniques. Within each technique, there were no significant differences between the native and the postoperative state in valgus laxity and joint gapping. No significant differences between the techniques were observed in cycles to failure and failure load.

Conclusion

Dual bracing restored native valgus joint laxity and medial joint gapping without overconstraining and provided similar primary stability regarding failure outcomes as established techniques. Furthermore, it was able to restore joint gapping in 120° of flexion significantly better than aUCL reconstruction.

Clinical Relevance

This study provides biomechanical data on the dual-bracing approach that may help surgeons to consider this new method of addressing acute humeral UCL lesions.

Analysis of Fracture Characteristic and Medial Collateral Ligament Injury Relationships in Terrible Triad Elbow Injuries

PURPOSE

The objectives of this study were to identify the relationship between fracture characteristics and medial collateral ligament (MCL) injuries in terrible triad injuries of the elbow.

METHODS

Between 2010 and 2018, 60 patients who underwent surgery for terrible triad elbow injuries were retrospectively reviewed. Using magnetic resonance imaging (MRI) assessments, patients were stratified into those who had intact or low-grade partial MCL tears (low-grade MRI-MCL group) and those who had high-grade partial or full-thickness MCL tears (high-grade MRI-MCL group). We also analyzed patients according to whether they underwent MCL repair surgery. Fractures of the radial head were assessed according to Mason's classification system and measurements of fracture fragment arc on axial cuts. Fractures of the coronoid processes were assessed according to the system of Regan and Morrey and measurements of coronoid process volumes.

RESULTS

Patients in the high-grade MRI-MCL group (28 patients) had a more comminuted and higher fragment arc of radial head fractures than those in the low-grade MRI-MCL group (32 patients) (143º ± 45º vs 119º ± 31º). However, the volume of coronoid fracture fragments was smaller in the high-grade MRI-MCL than in the low-grade MRI-MCL group (359 ± 325 mm³ vs 722 ± 448 mm³). The MCL repair group (22 patients) also had a more comminuted and higher fragment arc in radial head fractures (153º ± 44º vs 117º ± 31º) and a smaller coronoid process fracture volume (236 ± 224 mm³ vs 735 ± 419 mm³) than the non-MCL repair group (38 patients).

CONCLUSIONS

Our results demonstrated that high-grade MCL injuries are associated with comminuted and larger-sized radial head fractures, as well as smaller-sized coronoid process fractures in terrible triad injuries. In making a decision regarding surgical treatment, these fracture characteristics could help to predict the severity for MCL injury in terrible triad injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Injury patterns following simple elbow dislocation: radiological analysis implies existence of a pure valgus dislocation mechanism

INTRODUCTION

The 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 METHODS

The 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.

RESULTS

34 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.

CONCLUSIONS

Simple 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.

Severe traumatic valgus instability of the elbow: pathoanatomy and outcomes of primary operation

Background

The objective of the study was to depict the pathoanatomy of traumatic valgus instability of the elbow and to report clinical outcomes of primary operation.

Methods

Thirty-one patients presented with traumatic valgus instability of the elbow without dislocation. Thirty-one patients underwent surgical intervention of radial head fractures (28 open reduction and internal fixation and 3 radial head resection) and anatomical repair of the anterior bundle of medial collateral ligament (AMCL) with suture anchors. Twenty patients with disruption of the flexor-pronator tendon (FPT) and 14 patients with tears of the anterior capsule had primary repair of the FPT and anterior capsule simultaneously. Clinical outcomes were evaluated with the Mayo Elbow Performance Score (MEPS), modified hospital for special surgery assessment scale (HSS), and Disabilities of the Arm, Shoulder, and Hand (DASH) score.

Results

The median follow-up was 37.3 months (range, 15–53 months). Radial head fractures and complete avulsion of the medial collateral ligament (MCL) from its humeral footprint were confirmed in all patients intraoperatively. Intraoperative findings indicated disruption of the FPT in 20 patients and tears of the anterior capsule in 14 patients. Twenty-nine of 31 patients returned to previous activity and work levels within 6 months after surgery. The MEPS, modified HSS, and DASH score were 94 ± 4, 91 ± 5, and 8 ± 2 at the latest follow-up.

Conclusions

Radial head fractures with avulsion of the MCL can lead to severe valgus instability of the elbow. Primary operation to repair these disrupted structures, especially repair of the AMCL, can effectively restore valgus stability.