Simulated Cam Morphology of the Hip Changes Sacroiliac Motion During Hip Motion and Loading in a Cadaveric Model.

Purpose: To determine the relationship between cam morphology of the hip and ipsilateral sacroiliac motion compared to the native hip in a cadaveric model.

Methods: A simulated cam state was created using a 3-dimensional printed cam secured to the head-neck junction of 5 cadaveric hips. Hips were studied using a computed tomography-based optic metrology system and a 6 degree-of-freedom robot to exert an internal rotation torque at 3 different torque levels (6 N-m, 12 N-m, 18 N-m).

Effect of mechanical fatigue on commercial bioprosthetic TAVR valve mechanical and microstructural properties.

Valvular structural deterioration is of particular concern for transcatheter aortic valve replacements due to their suspected shorter longevity and increasing use in younger patient populations. In this work we investigated the mechanical and microstructural changes in commercial TAVR valves composed of both glutaraldehyde fixed bovine and porcine pericardium (GLBP and GLPP) following accelerated wear testing (AWT) as outlined in ISO 5840 standards. This provided greater physiological relevance to the loading compared to previous studies and by utilizing digital image correlation we were able to obtain strain contours for each leaflet pre and post fatigue and identify sites of fatigue damage.

The Frank Stinchfield Award: Assembly and Dissociation Forces Differ Between Commonly Used Dual Mobility Implants: A Biomechanical Study.

Background: Intraprosthetic dissociation (IPD) is a complication unique to dual mobility (DM) implants where the outer polyethylene head dissociates from the inner femoral head. Increasing reports of IPD at the time of closed reduction of large head DM dislocations prompted this biomechanical study evaluating the assembly and dissociation forces of DM heads.

Methods: We tested 17 polyethylene DM heads from 5 vendors.

Biomechanical Stability of Diaphyseal Ulnar Shaft Fractures and Ulnar Shortening Osteotomies After Fixation.

Background: To determine the amount of micromotion during forearm rotation after diaphyseal ulnar shaft fracture or osteotomy.

Methods: This was a biomechanical study using 7 paired-matched cadavers. The upper extremity was mounted in a custom rig and the forearm brought through full pronation and supination.

Anterolateral Acromioplasty Reduces Gliding Resistance Between the Supraspinatus Tendon and the Coracoacromial Arch in a Cadaveric Model.

Purpose: To investigate the gliding resistance dynamics between the supraspinatus (SSP) tendon and the coracoacromial arch, both before and after subacromial decompression (anterolateral acromioplasty) and acromion resection (acromionectomy).

Methods: Using 4 fresh-frozen cadaveric shoulders, acromion shapes were classified (2 type I and 2 type III according to Bigliani). Subacromial bursa and coracoacromial ligament maintenance replicated physiologic sliding conditions.

Moment arms of the anatomical subregions of the rotator cuff muscles during shoulder rotation.

Background: Rotator cuff muscles are responsible for humeral rotation. Moment arms of different regions of these muscles during humeral rotation were analyzed in neutral and abducted positions.

Methods: In eight cadaveric shoulders, subregions of the rotator cuff muscles were identified and their excursion during humeral rotation was measured in neutral and abducted positions from an internal rotation of 30° to an external rotation of 45°, with 15° increments, using a 3-D digitizing system.

Precise Limb Tourniquet Arterial Occlusion Pressure Determination using Real-Time Ultrasonography and a Capacitive-Based Force Sensor.

Background: Hemorrhage control prior to shock onset is increasingly recognized as a time-critical intervention. Although tourniquets (TQs) have been demonstrated to save lives, less is known about the physiologic parameters underlying successful TQ application beyond palpation of distal pulses. The current study directly visualized distal arterial occlusion via ultrasonography and measured associated pressure and contact force.

Moment arms from the anatomical subregions of the rotator cuff muscles during flexion.

Rotator cuff (RC) muscles act as force couples to stabilize the glenohumeral joint and enable shoulder motion. We investigated the moment arms of anatomical subregions of the supraspinatus (SSP), infraspinatus (ISP), subscapularis (SSC), and the teres minor muscles during flexion. Eight fresh-frozen cadaveric shoulders were obtained and the anatomical subregions of the RC muscles were identified.

Mechanical and strain behaviour of human Achilles tendon during in vitro testing to failure.

The Achilles tendon is the strongest tendon in the human body but its mechanical behaviour during failure has been little studied and the basis of its high tensile strength has not been elucidated in detail. In the present study, healthy, human, Achilles tendons were loaded to failure in an anatomically authentic fashion while the local deformation and strains were studied in real time, with very high precision, using digital image correlation (DIC). The values determined for the strength of the Achilles tendon were at the high end of those reported in the literature, consistent with the absence of a pre-existing tendinopathy in the samples, as determined by careful gross inspection and histology.

Prospective Study Assessing Impact of Ethylene Oxide Sterilization on Endoscopic Ultrasound Image Quality.

Background & Aims: Duodenoscope-associated transmission of infections has raised questions about efficacy of endoscope reprocessing using high-level disinfection (HLD). Although ethylene oxide (ETO) gas sterilization is effective in eradicating microbes, the impact of ETO on endoscopic ultrasound (EUS) imaging equipment remains unknown. In this study, we aimed to compare the changes in EUS image quality associated with HLD vs HLD followed by ETO sterilization.

Does Proximal Hamate Graft for Proximal Scaphoid Reconstruction Restore Native Wrist Kinematics?

Background: The objective of this study was to determine whether reconstruction of the proximal pole of the scaphoid with a proximal hamate graft restores native carpal kinematics.

Methods: A cadaveric study was designed assessing wrist kinematic after proximal hamate graft for proximal pole of the scaphoid nonunion. Wireless sensors were mounted to the carpus using a custom pin and suture anchor system to 8 cadavers.

Intrinsic Tendon Regeneration After Application of Purified Exosome Product: An In Vivo Study.

Background: Tendons are primarily acellular, limiting their intrinsic regenerative capabilities. This limited regenerative potential contributes to delayed healing, rupture, and adhesion formation after tendon injury.

Purpose: To determine if a tendon's intrinsic regenerative potential could be improved after the application of a purified exosome product (PEP) when loaded onto a collagen scaffold.

Radial Head Lag: A Possible Biomechanical Mechanism for Osteochondritis Dissecans of the Capitellum in Baseball Pitchers.

Background: Osteochondritis dissecans (OCD) of the capitellum is common in throwing athletes and is believed to result from repetitive overloading on the radiocapitellar (RC) joint, although the cause and mechanism remain unclear. The torsional forces (moments) generated by the triceps during elbow extension pull only on the ulna; therefore, the radial head moves passively across the capitellum and is effectively "dragged along" by the ulna. Any laxity in the proximal radioulnar joint could lead to asynchronous motion between the radius and ulna, resulting in the radial head lagging behind the coronoid and possibly malarticulating with the capitellum during such motion.

Three-dimensional surface strain analyses of simulated defect and augmented spine segments: A biomechanical cadaveric study.

While several studies have investigated fracture outcomes of intact vertebrae, fracture properties in metastatically-involved and augmented vertebrae are still far from understood. Consequently, this study was aimed to use 3D digital image correlation (3D-DIC) method to investigate the failure properties of spine segments with simulated metastatic lesions, segments augmented with poly(propylene fumarate) (PPF), and compare the outcomes with intact spines. To this end, biomechanical experiments accompanied by 3D-DIC were performed on spine segments consisting of three vertebrae and two intervertebral discs (IVDs) at loading rates of 0.

Mechanical Assessment of Tissue Properties During Tourniquet Application.

Introduction: Successful tourniquet application increases survival rate of exsanguinating extremity hemorrhage victims. Tactile feedback during tourniquet application training should reflect human tissue properties in order to increase success in the field. This study aims to understand the mechanical properties of a human limb during tourniquet application.

Biomechanical effectiveness of tendon transfers to restore active internal rotation in shoulder with deficient subscapularis with and without reverse shoulder arthroplasty.

Background: Loss of active shoulder internal rotation can be very disabling. Several tendon transfers have been described for the management of an irreparable subscapularis (SSC) tear. The purpose of this study was to determine and compare the internal rotation moment arm (IRMA) of the sternal head of the pectoralis major (PM), latissimus dorsi (LD), and teres major (TM) when transferred to different insertion sites to restore shoulder internal rotation with and without reverse shoulder arthroplasty (RSA).

Bankart repair alone in combined Bankart and superior labral anterior-posterior lesions preserves range of motion without compromising joint stability.

Hypothesis: The purpose was to investigate joint stability and range of motion after a Bankart repair without superior labral anterior-posterior (SLAP) repair (termed "Bankart repair") and after combined Bankart and SLAP repairs (termed "combined repair").

Methods: Eight fresh-frozen shoulders were used. Combined Bankart and SLAP lesions were created (10- to 6-o'clock positions).

The Biomechanical Consequences of Trapeziectomy and Partial Trapezoidectomy in the Treatment of Thumb Carpometacarpal and Scaphotrapeziotrapezoid Arthritis.

Purpose: To determine, using a biomechanical cadaveric model, whether, in the treatment of thumb carpometacarpal and scaphotrapeziotrapezoid arthritis, partial trapezoid resection following trapeziectomy causes carpal, specifically lunocapitate and scapholunate, instability.

Methods: Eight fresh-frozen mid-forearm cadaver specimens with type I lunates and devoid of basilar thumb arthritis were used in the study. Specimens were mounted onto a wrist simulator applying cyclical wrist flexion/extension and radial/ulnar deviation motions.

The effect of subscapularis muscle contraction on coaptation of anteroinferior glenohumeral ligament-labrum complex after Bankart repair.

Facilitation of healing is important for the anteroinferior glenohumeral ligament-labrum complex (AIGHL-LC) after Bankart repair in shoulder dislocation. The purpose of this study was to investigate the effect of subscapularis muscle loading on contact area and contact pressure between the subscapularis and AIGHL-LC and between the glenoid bone and the AIGHL-LC following Bankart repair. Twenty-two fresh-frozen cadaveric shoulders were used.

The Effect of Proximal Hamate Osteotomy on Carpal Kinematics for Reconstruction of Proximal Pole Scaphoid Nonunion With Avascular Necrosis.

The purpose of this study is to determine the effects of proximal hamate transfer for proximal pole scaphoid reconstruction upon carpal kinematics. Eight fresh-frozen cadaveric wrists underwent evaluation of their radiocarpal and midcarpal motion after proximal hamate osteotomy. A wrist simulator was used to apply cyclical tension to the flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), and extensor carpi radialis longus and brevis stitched together (ECR).