Labral lesions in first-time traumatic anterior shoulder dislocation: it’s more than just Bankart …

<jats:title>Abstract</jats:title><jats:sec><jats:title>Introduction</jats:title><jats:p>Traumatic anterior shoulder dislocation occurs frequently and usually affects young, active male patients. Detachment of the anteroinferior labrum, known as the Bankart lesion, is a common result. However, more extensive entities including bony lesions and disruptions of the labral ring can also be found. The aim of the present work was to analyze all cases of first-time traumatic anterior shoulder dislocation at a level‑1 trauma center with regard to the type of labral lesion. Focus was placed on the frequency and distribution of complex lesions and the extent of the surgical repair.</jats:p></jats:sec><jats:sec><jats:title>Patients and methods</jats:title><jats:p>The clinical database of a level‑1 trauma center with a specialized shoulder unit was searched to identify all patients with first-time anterior shoulder dislocation treated between 2015 and 2019. Of 224 patients, 110 underwent primary surgical repair after first-time dislocation (mean age 40 years).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>A total of 62% of patients had only a soft tissue injury, while 38% (<jats:italic>n</jats:italic> = 40) showed a bony Bankart lesion/fracture of the glenoid fossa with a mean defect size of 26%. In only 31% of patients (<jats:italic>n</jats:italic> = 34), a <jats:italic>classic</jats:italic>Bankart repair was performed, whereas the remaining 69% underwent additional procedures.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>In this series of surgically treated first-time traumatic anterior shoulder dislocations, the majority of cases presented with more complex lesions than an isolated classic Bankart lesion. The risk for bony involvement and associated pathologies, such as cuff tears and greater tuberosity fracture, increases with age and requires a more extensive surgical approach. Disruption of the labral ring was frequently found in both soft tissue and bony lesions and directly affected the surgical procedure.</jats:p></jats:sec&gt

Comparison of Different Fixation Techniques of the Long Head of the Biceps Tendon in Superior Capsule Reconstruction for Irreparable Posterosuperior Rotator Cuff Tears: A Dynamic Biomechanical Evaluation

Background: In the past decade, superior capsular reconstruction has emerged as a potential surgical approach in young patients with irreparable posterosuperior rotator cuff tears (RCT) and absence of severe degenerative changes. Recently, the use of locally available and biological viable autografts, such as the long head of the biceps tendon (LHBT) for SCR has emerged, with promising early results. Purpose/Hypothesis: The purpose of this study was to investigate the effect of using the LHBT for reconstruction of the superior capsule on shoulder kinematics, along with different fixation constructs in a dynamic biomechanical model. The authors hypothesized that each of the 3 proposed fixation techniques would restore native joint kinematics, including glenohumeral superior translation (ghST), maximum abduction angle (MAA), maximum cumulative deltoid force (cDF), and subacromial peak contact pressure (sCP). Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders (mean age, 53.4 ± 14.2 years) were tested using a dynamic shoulder simulator. Each specimen underwent the following 5 conditions: (1) intact, (2) irreparable posterosuperior rotator cuff tear (psRCT), (3) V-shaped LHBT reconstruction, (4) box-shaped LHBT reconstruction, and (5) single-stranded LHBT reconstruction. MAA, ghST, cDF and sCP were assessed in each tested condition. Results: Each of the 3 LHBT techniques for reconstruction of the superior capsule significantly increased MAA while significantly decreasing ghST and cDF compared with the psRCT (P <.001 and P <.001, respectively). Additionally, the V-shaped and box-shaped techniques significantly decreased sCP (P =.009 and P =.016, respectively) compared with the psRCT. The V-shaped technique further showed a significantly increased MAA (P <.001, respectively) and decreased cDF (P =.042 and P =.039, respectively) when compared with the box-shaped and single-stranded techniques, as well as a significantly decreased ghST (P =.027) when compared with the box-shaped technique. Conclusion: In a dynamic biomechanical cadaveric model, using the LHBT for reconstruction of the superior capsule improved shoulder function by preventing superior humeral migration, decreasing deltoid forces and sCP. As such, the development of rotator cuff tear arthropathy in patients with irreparable psRCTs could potentially be delayed. Clinical Relevance: Using a biologically viable and locally available LHBT autograft is a cost-effective, potentially time-saving, and technically feasible alternative for reconstruction of the superior capsule, which may result in favorable outcomes in irreparable psRCTs. Moreover, each of the 3 techniques restored native shoulder biomechanics, which may help improve shoulder function by preventing superior humeral head migration and the development of rotator cuff tear arthropathy in young patients with irreparable rotator cuff tears

The Glenolabral Articular Disruption Lesion Is a Biomechanical Risk Factor for Recurrent Shoulder Instability

PURPOSE: To investigate the biomechanical effect of a glenolabral articular disruption (GLAD) lesion on glenohumeral laxity. METHODS: Human cadaveric glenoids (n = 10) were excised of soft tissue, including the labrum to focus on the biomechanical effects of osteochondral surfaces. Glenohumeral dislocations were performed in a robotic test setup, while displacement forces and three-dimensional morphometric properties were measured. The stability ratio (SR), a biomechanical characteristic for glenohumeral stability, was used as an outcome parameter, as well as the path of least resistance, determined by a hybrid robot displacement. The impacts of chondral and bony defects were analyzed related to the intact glenoid. Statistical comparison of the defect states on SR and the path of least resistance was performed using repeated-measures ANOVA and Tukey’s post hoc test for multiple comparisons (P < .05). The relationship between concavity depth and SR was approximated in a nonlinear regression. RESULTS: The initial SR of the intact glenoid (28.3 ± 7.8%) decreased significantly by 4.7 ± 3% in case of a chondral defect (P = .002). An additional loss of 3.2 ± 2.3% was provoked by a 20% bony defect (P = .004). The path of least resistance was deflected significantly more inferiorly by a GLAD lesion (2.9 ± 1.8°, P = .002) and even more by a bony defect (2.5 ± 2.9°, P = .002). The nonlinear regression with concavity depth as predictor for the SR resulted in a high correlation coefficient (r = .81). CONCLUSIONS: Chondral integrity is an important contributor to the SR. Chondral defects as present in GLAD lesions may cause increased laxity, influence the humeral track on the glenoid during dislocation, and represent a biomechanical risk factor for a recurrent instability

Cerclage performance analysis – a biomechanical comparison of different techniques and materials

Abstract Background Wire cerclages play a fundamental role in fracture fixation. With an increasing variety of designs being commercially available the question arises which cerclage should be used. This study investigates the biomechanical properties of metallic and non-metallic cerclages and their different application-types. Furthermore, potential influence of muscular interposition between bone and cerclage constructs was tested. Methods Samples of the following four different cerclage types were tested on 3D printed models of human humeri as well as on human cadaveric humeri with and without muscular interposition: Titanium Cable Cerclage (CC), Steel Wire Cerclage (SWC), Suture Tape (ST), Suture Tape Cerclage (STC) with both single- (sSTC) and double-loop application (dSTC). A preinstalled self-locking mechanism secured by the provided tensioner in the STCs being the main difference to the STs. Cyclic loading was performed to 1 kN and then linearly to a maximum load of 3 kN. Statistical analysis was performed using either one-way ANOVA and post-hoc Tukey or Kruskal–Wallis and post-hoc Dunn test depending on normalization of data (p < 0.05). Results Whilst all cerclage options could withstand high loads during failure testing, only within the CC and dSTC group, all samples reached the maximal testing load of 3000 N without any failure. The SWC reached 2977.5 ± 63.6 N, the ST 1970.8 ± 145.9 N, and the sSTC 1617.0 ± 341.6 N on average. Neither muscular interposition nor bone quality showed to have a negative influence on the biomechanical properties of the cerclage constructs, presenting no significant differences. Conclusion All tested cerclage constructs produce reliable stability but differ in their resulting compression forces, in a simplified fracture model. Therefore, non-metallic cerclage alternatives can provide similar stability with less compression and stiffness to metallic cable constructs, but they may offer several advantages and could possibly provide future benefits. Especially, by offering more elasticity without losing overall stability, may offer a biologic benefit. Installing any cerclage constructs should be performed carefully, especially if poor bone quality is present, as the tightening process leads to high forces on the construct