Hyper extension-internal rotation (HERI): A new test for anterior gleno-humeral instability

Dynamic Anterior Stabilization with Hill-Sachs Remplissage Can be Employed in Skeletally Immature Patients-Operative Technique

BACKGROUND

Numerous studies indicate that glenoid bony augmentation raises the risk of complications during and after surgery. On the other hand, repairing the labrum alone in cases with subcritical glenoid bone loss results in recurrent instability and persistent apprehension. As a result, recent advancements in shoulder instability surgery prioritize fully restoring the anterior shoulder restraint.

OPERATIVE TECHNIQUE

A novel method for treating recurrent anterior shoulder instability with subcritical glenoid bone loss and off-track Hill-Sachs lesion in skeletally immature patients is suggested: the use of dynamic anterior stabilization technique incorporating the long head of the biceps tendon onto the anterior glenoid rim via trans-subscapular transfer, in conjunction with Hill-Sachs remplissage. A practical, step-by-step surgical technique for a complete reconstruction of the anterior capsule-labral-ligamentous complex is provided. This involves utilizing a soft-tissue dynamic anterior sling, achieved through the trans-subscapularis transfer of the long head of the biceps tendon at the glenoid level. The procedure concludes with a Hill-Sachs remplissage to further prevent off-track events and alleviate apprehension.

CONCLUSION

Dynamic anterior stabilization is a suitable approach for addressing recurring anterior shoulder instability in skeletally immature patients who have subcritical glenoid bone loss and bipolar bone lesions.

The development and evaluation of an in-vitro shoulder simulator with active muscle simulation

The purpose of the present study was to develop a novel active in-vitro shoulder simulator to emulate all forms of planar and non-planar glenohumeral motions with active muscle simulation on cadaver specimens or shoulder models and to critically evaluate its performance. A physiologic shoulder simulator, driven using simulated muscle force, was developed to dynamically realize accurate kinematic control in all three rotational degrees of freedom (DOF) under physiological kinetic boundaries. The control algorithm of the simulator was implemented using three parallel running independent control loops, which regulate the forces of individual muscles in the respect DOF and work asynchronously in disparate sequences adapted to specific motions (abduction, flexion/extension and rotation). Three cadaveric specimens were used to evaluate the kinematic and kinetic performance of the simulator during simulated motions. High kinematic accuracy (maximum mean deviation ≤ 2.35° and RMSE 1.13°) and repeatability (maximum and average SD of ≤ 1.21° and 0.67°) were observed in all three rotational DOF investigated. The reliabilities of all individual muscle forces actuated in the simulator during planar and non-planar motions were generally excellent, with the 95% CIs of ICC estimates of > 0.90 for most instances (30/36). A novel shoulder simulator with active muscle simulation was developed and evaluated. Its capability to reproduce kinematics and kinetics in a physiological range for all DOF was systematically evaluated for multiple kinetic and kinematic outcome variables. The presented simulator is a powerful tool for investigating the biomechanics of physiological and pathological shoulder joints and to evaluate various surgical interventions. Acquisition of reliable data in joint kinetics and translational kinematics during active motions is critical to assess shoulder pathologies and appropriate treatments. We provide a unique muscle activated physiologic shoulder simulator, which allows the comprehensive acquisition of joint kinematic and kinetic data during repeated realistic planar and non-planar motions.

Bench, Bar, and Ring Dips: Do Kinematics and Muscle Activity Differ?

The purpose of this study was to profile and compare the kinematics, using 3D motion capture, and muscle activation patterns, using surface electromyography (sEMG), of three common dip variations; the bench, bar, and ring dips. Thirteen experienced males performed four repetitions of each dip variation. For each participant, repetitions 2-4 were time-normalized and then averaged to produce a mean value for all kinematic and sEMG variables. The mean maximal joint angles and mean peak sEMG amplitudes were compared between each variation using a one-way ANOVA with repeated measures. Several significant differences (p < 0.05) between dip variations were observed in both kinematic and sEMG data. The bench dip predominantly targets the triceps brachii but requires greater shoulder extension range. The mean peak triceps brachii activation was 0.83 ± 0.34 mV on the bench, 1.04 ± 0.27 mV on the bar, and 1.05 ± 0.40 mV on the ring. The bar dip is an appropriate progression from the bench dip due to the higher peak muscle activations. The ring dip had similar peak activations to the bar dip, with three muscles increasing their activation intensities further. These findings have implications for practitioners prescribing the dip, particularly to exercisers with a history of shoulder pain and injury.

Global Perspectives on Management of Shoulder Instability: Decision Making and Treatment

The glenohumeral joint is prone to instability. Patients with instability should have a physical examination. Imaging studies can provide additional information. Classification schemes that into account soft tissue pathology, neuromuscular control, bone loss, and activity level. An arthroscopic Bankart repair is the mainstay for unidirectional instability. Bone block procedures are indicated for patients with bone loss or a failed attempt at stabilization surgery. The arthroscopic Latarjet is a promising option for these patients. For patients with multidirectional instability, prolonged rehabilitation is indicated, followed by capsular plication or inferior capsular shift if instability is unresponsive to physical therapy.