Collagen scaffold-seeded iTenocytes accelerate the healing and functional recovery of Achilles tendon defects in a rat model.

Introduction: Tendon injuries represent an ongoing challenge in clinical practice due to poor regenerative capacity, structure, and biomechanical function recovery of ruptured tendons. This study is focused on the assessment of a novel strategy to repair ruptured Achilles tendons in a Nude rat model using stem cell-seeded biomaterial.

Methods: Specifically, we have used induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells (iMSCs) overexpressing the early tendon marker Scleraxis (SCX, iMSC, iTenocytes) in combination with an elastic collagen scaffold.

Exercise improves load bearing bone structural properties in female secreted protein acidic and rich in cysteine (SPARC) null mice but not in males.

Secreted protein acidic and rich in cysteine (SPARC) is the most abundant glycoprotein in bone and is thought to play a critical role in bone remodeling and homeostasis. However, the effect of SPARC in relation to gender and exercise on bone quality is not well understood. The purpose of this study was to quantify differences in the structural and biomechanical properties between calvarial and femoral bone from male and female wild-type (WT) and SPARC null (SPARC) mice as well as the ability of exercise to rescue bone health.

Biomechanical evaluation of a central collinear entry reconstruction nail for femoral neck fracture prophylaxis.

Introduction: Reconstruction nails are commonly used to treat proximal femur fractures, with cephalic screw placement for femoral neck "prophylaxis" becoming standard practice. These implants are traditionally introduced through piriformis fossa (PF) or greater trochanter (GT) entry portals. A third "central collinear" (CC) portal has been proposed that allows entry along the femoral anatomic axis and central placement of cephalic screws.

Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction Between Palmaris Longus Autograft and Knee Medial Collateral Ligament Allograft.

Background: Medial ulnar collateral ligament (mUCL) injury can cause significant pain and alter throwing mechanics. Common autograft options for mUCL reconstruction (UCLR) include the palmaris longus (PL) and hamstring tendons. Allograft use may reduce donor site morbidity and decrease function related to PL autografts.

Polymethylmethacrylate (PMMA) Augmentation Enhances the Mechanical Characteristics of Midfoot Beam Constructs in Charcot Neuroarthropathy Cadaver Model.

Background: Even with the best conservative care, patients with Charcot neuroarthropathy (CN) of the foot and ankle often ulcerate, increasing their risk of infection, amputation, and death. Surgical fixation has been associated with risk of recurrent ulceration, potentially due to poor bone quality prone to recurrent deformity and ulceration. We propose midfoot beam reconstruction with PMMA augmentation as a novel means of improving fixation.

Contributions of the Abductor Muscles to Rotational and Distractive Stability of the Hip in a Biomechanical Cadaveric Model.

Background: The gluteus minimus (GMin) and gluteus medius (GMed) are important dynamic stabilizers of the hip, but quantitative data on their biomechanical roles in stabilizing the hip are currently lacking.

Purpose: To (1) establish a reproducible biomechanical cadaveric model of the hip abductor complex and (2) characterize the effects of loading the GMin and GMed on extraneous femoral rotation and distraction.

Study Design: Controlled laboratory study.

Novel bisphosphonate-based cathepsin K-triggered compound targets the enthesis without impairing soft tissue-to-bone healing.

Osteoadsorptive fluorogenic sentinel 3 (OFS-3) is a recently described compound that contains a bone-targeting bisphosphonate (BP) and cathepsin K (Ctsk)-triggered fluorescence signal. A prior study in a murine Achilles repair model demonstrated its effectiveness at targeting the site of tendon-to-bone repair, but the intrinsic effect of this novel bisphosphonate chaperone on tendon-to-bone healing has not been previously explored. We hypothesized that application of this bisphosphonate-fluorophore cargo conjugate would not affect the biomechanical properties or histologic appearance of tendon-bone repairs.

Retention of Human iPSC-Derived or Primary Cells Following Xenotransplantation into Rat Immune-Privileged Sites.

In regenerative medicine, experimental animal models are commonly used to study potential effects of human cells as therapeutic candidates. Although some studies describe certain cells, such as mesenchymal stromal cells (MSC) or human primary cells, as hypoimmunogenic and therefore unable to trigger strong inflammatory host responses, other studies report antibody formation and immune rejection following xenotransplantation. Accordingly, the goal of our study was to test the cellular retention and survival of human-induced pluripotent stem cell (iPSCs)-derived MSCs (iMSCs) and primary nucleus pulposus cells (NPCs) following their xenotransplantation into immune-privileged knee joints (14 days) and intervertebral discs (IVD; 7 days) of immunocompromised Nude and immunocompetent Sprague Dawley (SD) rats.

Biomechanical Properties of Knee Medial Collateral Ligament Compared to Palmaris Longus for Ulnar Collateral Ligament Reconstruction.

Ulnar collateral ligament reconstruction (UCLR) is frequently performed among injured overhead-throwing athletes. One of the most common graft choices when performing a UCLR is the ipsilateral palmaris longus tendon (PL). The purpose of this study was to investigate the material properties of aseptically processed cadaveric knee collateral ligaments (kMCL) as a potential graft source for UCLR and compare them to the gold standard PL autograft.

iPSC-derived tenocytes seeded on microgrooved 3D printed scaffolds for Achilles tendon regeneration.

Tendons and ligaments have a poor innate healing capacity, yet account for 50% of musculoskeletal injuries in the United States. Full structure and function restoration postinjury remains an unmet clinical need. This study aimed to assess the application of novel three dimensional (3D) printed scaffolds and induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) overexpressing the transcription factor Scleraxis (SCX, iMSC ) as a new strategy for tendon defect repair.

Racial and Sex Disparities in Resident Attrition Among Surgical Subspecialties.

Importance: Racial and sex disparities are prevalent in surgical trainees. Although retrospective studies on resident attrition have been conducted for individual specialties, this study analyzes racial and sex differences in resident attrition among all surgical subspecialties over an 18-year period.

Objective: To evaluate the racial and sex differences in resident attrition among surgical specialties over an 18-year period.

Suture Tape Augmentation Increases the Time-Zero Stiffness and Strength of Anterior Cruciate Ligament Grafts: A Cadaveric Study.

Purpose: To determine the postsurgical strength and stiffness of anterior cruciate ligament (ACL) reconstructions with (ACLR-SA) and without suture tape augmentation (ACLR) in a human cadaveric model.

Methods: Eight matched pairs of cadaveric knees were tested intact and after bone-patellar tendon-bone ACL reconstruction. Specimens were potted and loaded onto a mechanical testing system, and an anterior drawer force of 88N was applied at 0°, 15°, 30°, 60°, and 90° of flexion.

Comparable Torque to Failure Using the Simple Stich Versus the Figure-of-Eight Configuration for Hip Capsular Closure Following an Interportal Capsulotomy: A Cadaveric Study.

Purpose: To measure and compare the torque to failure and stiffness of the capsular repair construct consisting of four-suture simple stitches to a two-figure of eight stitches repair construct in external rotation following an interportal capsulotomy.

Methods: Six pairs of fresh-frozen cadaveric hemipelves were divided into two capsular repair groups. All hips underwent a 40-mm interportal capsulotomy from the 12 o'clock position to the 3 o'clock position.

Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction With and Without Suture Augmentation.

Background: A common concern associated with elbow ulnar collateral ligament (UCL) reconstruction is the amount of time required for recovery and rehabilitation. For example, for Major League Baseball pitchers, the average time to return to competition ranges from 13.8 to 20.

An Increased Allograft Width for Circumferential Labral Reconstruction Better Restores Distractive Stability of the Hip: A Cadaveric Biomechanical Analysis.

Background: Questions remain about whether circumferential labral reconstruction (CLR) using an iliotibial band (ITB) allograft can effectively restore the labral suction seal of the hip.

Hypotheses: (1) CLR with an ITB allograft >6.5 mm would restore distractive stability force to that of the intact labrum.

Biomechanical Comparison of UCL Repair Using Suspensory Fixation Versus UCL Reconstruction.

Background: Medial ulnar collateral ligament (mUCL) repair is growing in popularity as a treatment for younger athletes with mUCL tears. One of the most recent techniques utilizes a collagen-coated suture tape to augment the repair. The most popular repair technique uses a screw for proximal fixation in the humerus.

Proximal Overresection During Femoral Osteochondroplasty Negatively Affects the Distractive Stability of the Hip Joint: A Cadaver Study.

Background: Contact between the acetabular labrum and articular cartilage of the femoral head creates a suction seal that helps maintain stability of the femoral head in the acetabulum. A femoral osteochodroplasty may occasionally extend proximally into the femoral head, diminishing the articular surface area available for sealing contact.

Purpose: To determine whether proximal overresection decreases the rotational and distractive stability of the hip joint.

Characterization of Infraspinatus Tendon Anatomy: The Soft-Tissue Portion of Remplissage.

Purpose: To characterize the morphology of the infraspinatus (IS) tendon and evaluate the bony anatomy of the humeral head (HH) to determine if there is a correlation between HH measurements and the amount of available IS tendon.

Methods: The superior-inferior width as well as the medial-lateral (M-L) length of the inferior and superior portions of the IS tendon were measured in 15 human cadaveric shoulders. Three measurements were then obtained for each corresponding humeral head: (1) anterior to posterior (A-P) distance, (2) midcoronal humeral head distance (MCHH), and (3) M-L distance.

Posterior Lateral Meniscal Root Tears Increase Strain on the Reconstructed Anterior Cruciate Ligament: A Cadaveric Study.

Purpose: To quantify the amount of strain across an anterior cruciate ligament reconstruction (ACLR) before and after a lateral meniscus (LM) posterior root complex tear and determine whether a meniscal root repair effectively protects the ACLR against excessive strain.

Methods: Fresh-frozen cadaveric knees were tested with an 88-N anterior drawer force and an internal and external torque of 5-Nm applied at 0°, 15°, 30°, 60°, and 90° of flexion. A simulated pivot shift was also applied at 0, 15, and 30° of flexion.

Pie-Crusting Capsulotomy Provides Similar Visualization With Increased Repair Stiffness Compared With a T-Capsulotomy: A Biomechanical Study.

Purpose: To compare the area of visualization, capsular stiffness, and strength between the pie-crusting capsulotomy technique and the T-capsulotomy technique following repair.

Methods: Eight matched pairs of fresh-frozen cadaveric hips (n = 16) were divided to either T-capsulotomy or pie-crusting capsulotomy followed by subsequent repair. The area of visualization was measured for all capsulotomy states using a digitizing probe.

Hip Adductor Longus Tendon Origin Anatomy Is Consistent and May Inform Surgical Reattachment.

Purpose: To define the topographic anatomy of the footprint of the adductor longus origin on the pubis and its underlying bony morphology to better inform surgical repair of adductor longus tendon injuries.

Methods: Five cadaveric pelvis specimens were dissected, making 10 adductor footprints available for analysis. The adductor longus tendon origin was isolated and the surrounding tissue debrided.

Neural crest-derived mesenchymal progenitor cells enhance cranial allograft integration.

Replacement of lost cranial bone (partly mesodermal and partly neural crest-derived) is challenging and includes the use of nonviable allografts. To revitalize allografts, bone marrow-derived mesenchymal stromal cells (mesoderm-derived BM-MSCs) have been used with limited success. We hypothesize that coating of allografts with induced neural crest cell-mesenchymal progenitor cells (iNCC-MPCs) improves implant-to-bone integration in mouse cranial defects.

Advanced Glycation End Product Inhibitor Pyridoxamine Attenuates IVD Degeneration in Type 2 Diabetic Rats.

Type 2 diabetes mellitus (T2DM) is associated with advanced glycation end product (AGE) enrichment and considered a risk factor for intervertebral disc (IVD) degeneration. We hypothesized that systemic AGE inhibition, achieved using pyridoxamine (PM), attenuates IVD degeneration in T2DM rats. To induce IVD degeneration, lumbar disc injury or sham surgery was performed on Zucker Diabetic Sprague Dawley (ZDSD) or control Sprague Dawley (SD) rats.

Assessing the Resident Progenitor Cell Population and the Vascularity of the Adult Human Meniscus.

Purpose: To identify, characterize, and compare the resident progenitor cell populations within the red-red, red-white, and white-white (WW) zones of freshly harvested human cadaver menisci and to characterize the vascularity of human menisci using immunofluorescence and 3-dimensional (3D) imaging.

Methods: Fresh adult human menisci were harvested from healthy donors. Menisci were enzymatically digested, mononuclear cells isolated, and characterized using flow cytometry with antibodies against mesenchymal stem cell surface markers (CD105, CD90, CD44, and CD29).