A novel mouse model of hindlimb joint contracture with 3D-printed casts.

Stiff joints formed after trauma, surgery or immobilization are frustrating for surgeons, therapists and patients alike. Unfortunately, the study of contracture is limited by available animal model systems, which focus on the utilization of larger mammals and joint trauma. Here we describe a novel mouse-based model system for the generation of joint contracture using 3D-printed clamshell casts.

En bloc excision of sacroiliac chondrosarcoma aided by 3D laser printed modeling and stereotactic navigation.

The surgical management of sacro-iliac chondrosarcomas is challenging given their intimate relationship to the nerves and vessels of the pelvis. Osteotomies for en bloc excision can be challenging because of lack of visualization and high risk of injury to pelvic structures. The use of three-dimensional (3D) printed models helps conceptualize the tumor relative to the patient's anatomy.

Comparing cost and print time estimates for six commercially-available 3D printers obtained through slicing software for clinically relevant anatomical models.

Background: 3D printed patient-specific anatomical models have been applied clinically to orthopaedic care for surgical planning and patient education. The estimated cost and print time per model for 3D printers have not yet been compared with clinically representative models across multiple printing technologies. This study investigates six commercially-available 3D printers: Prusa i3 MK3S, Formlabs Form 2, Formlabs Form 3, LulzBot TAZ 6, Stratasys F370, and Stratasys J750 Digital Anatomy.

Mechanosensitive Control of Articular Cartilage and Subchondral Bone Homeostasis in Mice Requires Osteocytic Transforming Growth Factor β Signaling.

Objective: Transforming growth factor β (TGFβ) signaling plays a complex tissue-specific and nonlinear role in osteoarthritis (OA). This study was conducted to determine the osteocytic contributions of TGFβ signaling to OA.

Methods: To identify the role of osteocytic TGFβ signaling in joint homeostasis, we used 16-week-old male mice (n = 9-11 per group) and female mice (n = 7-11 per group) with an osteocyte-intrinsic ablation of TGFβ receptor type II (TβRII mice) and assessed defects in cartilage degeneration, subchondral bone plate (SBP) thickness, and SBP sclerostin expression.

Identifying a commercially-available 3D printing process that minimizes model distortion after annealing and autoclaving and the effect of steam sterilization on mechanical strength.

Background: Fused deposition modeling 3D printing is used in medicine for diverse purposes such as creating patient-specific anatomical models and surgical instruments. For use in the sterile surgical field, it is necessary to understand the mechanical behavior of these prints across 3D printing materials and after autoclaving. It has been previously understood that steam sterilization weakens polylactic acid, however, annealing heat treatment of polylactic acid increases its crystallinity and mechanical strength.

3D printed PLA Army-Navy retractors when used as linear retractors yield clinically acceptable tolerances.

Background: Modern low-cost 3D printing technologies offer the promise of access to surgical tools in resource scarce areas, however optimal designs for manufacturing have not yet been established. We explore how the optimization of 3D printing parameters when manufacturing polylactic acid filament based Army-Navy retractors vastly increases the strength of retractors, and investigate sources of variability in retractor strength, material cost, printing time, and parameter limitations.

Methods: Standard retractors were printed from various polylactic acid filament spools intra-manufacturer and inter-manufacturer to measure variability in retractor strength.

Osteocyte dysfunction promotes osteoarthritis through MMP13-dependent suppression of subchondral bone homeostasis.

Osteoarthritis (OA), long considered a primary disorder of articular cartilage, is commonly associated with subchondral bone sclerosis. However, the cellular mechanisms responsible for changes to subchondral bone in OA, and the extent to which these changes are drivers of or a secondary reaction to cartilage degeneration, remain unclear. In knee joints from human patients with end-stage OA, we found evidence of profound defects in osteocyte function.

Clavicle Fracture Malunion Treated with an Osteotomy Guided by a Three-Dimensional-Printed Model: A Case Report.

Case: This case report describes the management of a chronic and symptomatic clavicle malunion with use of a 3-dimensional (3D)-printed model during the preoperative surgical planning.

Conclusion: The use of 3D printing has many applications in the medical field. Constant improvement in the quality of 3D printing has contributed to its increased use in a variety of surgeries.

Rotator Cuff Disease: Treatment Options and Considerations.

Rotator cuff disease encompasses a broad spectrum of injury and pathology with an increasing incidence with age. Pain with overhead activity, localizing to the deltoid region, and loss of active range of motion of the shoulder are among the most common presenting symptoms. Treatment options are dependent on the extent of disease and patient symptoms, and may range from physical therapy to surgical repair using a variety of possible techniques.

The Effects of Topical Vancomycin on Mesenchymal Stem Cells: More May Not Be Better.

Background: The use of topical vancomycin is increasingly popular in spine surgery. Large retrospective reviews suggest that topical vancomycin provides a cost-effective decrease in post-operative infection. Currently, there is little that is known about the maximum dose that can be applied locally.

Kartogenin treatment prevented joint degeneration in a rodent model of osteoarthritis: A pilot study.

Osteoarthritis (OA) is a major degenerative joint disease characterized by progressive loss of articular cartilage, synovitis, subchondral bone changes, and osteophyte formation. Currently there is no treatment for OA except temporary pain relief and end-stage joint replacement surgery. We performed a pilot study to determine the effect of kartogenin (KGN, a small molecule) on both cartilage and subchondral bone in a rat model of OA using multimodal imaging techniques.

Novel mouse model of spinal cord injury-induced heterotopic ossification.

Heterotopic ossification (HO) develops in about 20% to 30% of patients with spinal cord injury (SCI) and significantly impairs their rehabilitation. There is no effective prevention or treatment for this condition at this time. Our current understanding of its etiology and pathophysiology is limited partially due to the lack of clinically relevant animal models.

Reduction of environmental temperature mitigates local anesthetic cytotoxicity in bovine articular chondrocytes.

The purpose of this study was to assess whether reducing environmental temperature will lead to increased chondrocyte viability following injury from a single-dose of local anesthetic treatment. Bovine articular chondrocytes from weight bearing portions of femoral condyles were harvested and cultured. 96-well plates were seeded with 15,000 chondrocytes per well.

Joint instability and cartilage compression in a mouse model of posttraumatic osteoarthritis.

Joint instability and cartilage trauma have been previously studied and identified as key mediators in the development of posttraumatic osteoarthritis (PTOA). The purpose of this study was to use an in vivo model to compare the effect of joint instability, caused by the rupture of the anterior cruciate ligament (ACL), versus cartilage compression. In this study, mice were subjected to cyclical axial loads of twelve Newtons (N) for 240 cycles or until the ACL ruptured.

Cytotoxicity of local anesthetics on human mesenchymal stem cells.

Background: Local anesthetics are frequently delivered intra-articularly to provide perioperative pain control. Previous studies have shown that the commonly used drugs lidocaine, ropivacaine, and bupivacaine can be toxic to human chondrocytes. The present study was conducted to determine whether the toxic effects of local anesthetics on human chondrocytes also extend to human mesenchymal stem cells.

Effects of adding epinephrine to arthroscopic irrigation fluid on cultured chondrocyte survival in vitro.

Purpose: This study evaluates the effect of low doses of epinephrine contained in common arthroscopic irrigation solutions on viability of in vitro human articular chondrocytes during short-term exposure.

Methods: Isolated cultured human chondrocytes were treated with culture medium, normal saline solution, 1:300,000 epinephrine solution (equivalent to 10 mL of 1:1,000 epinephrine added to a 3-L saline solution bag), or 1:3,000,000 epinephrine solution (equivalent to 1 mL of 1:1,000 epinephrine added to a 3-L saline solution bag) for 1 hour (N = 84). Twenty-four hours after treatment, chondrocyte viability was measured.

Chondrocyte apoptosis after simulated intraarticular fracture: a comparison of histologic detection methods.

Accurate evaluation of programmed cell death, or apoptosis, in chondrocytes is essential to studying cartilage injury. We evaluated four methods of detecting chondrocyte-programmed cell death in formalin-fixed, paraffin-embedded cartilage after experimental osteochondral fracture. Human osteochondral explants were subjected to experimental fracture in a manner known to induce high levels of chondrocyte-programmed cell death.

Inhibition of MMP2/MMP9 after spinal cord trauma reduces apoptosis.

Study Design: Randomized controlled trial.

Objective: To characterize the increase in gelatinase A (MMP2) activity after spinal cord injury (SCI) in the mouse model, and the effects of MMP2/MMP9 inhibition on apoptotic cells.

Summary Of Background Data: Clinical consequences of SCI are due to a series of secondary injury cascades.

Chondrocyte apoptosis: implications for osteochondral allograft transplantation.

Osteochondral allograft transplantation is a useful technique to manage larger articular cartilage injuries. One factor that may compromise the effectiveness of this procedure is chondrocyte cell death that occurs during the storage, preparation, and implantation of the osteochondral grafts. Loss of viable chondrocytes may negatively affect osteochondral edge integration and long-term function.

Hemodynamic and oxygen transport patterns after head trauma and brain death: implications for management of the organ donor.

Objectives: The aims of the present study were to describe the temporal hemodynamic and oxygen transport patterns of patients with head injuries as well as the patterns of those who became brain dead to better understand the role of underlying central regulatory hemodynamic mechanisms and ultimately to improve rates of organ donation.

Methods: We studied 388 consecutive noninvasively monitored patients with severe head trauma; 79 of these became brain dead. Monitoring was started shortly after admission to the emergency department and was designed to describe the sequence of cardiac, pulmonary, and tissue perfusion functions by cardiac index (CI), mean arterial pressure, heart rate, arterial saturation by pulse oximetry (Sapo2), and transcutaneous oxygen and carbon dioxide (Ptco2/Fio2 and Ptcco2) patterns.

Survival, hemodynamics, and tissue oxygenation after head trauma.

Background: The aims of this study were to describe the early time course of hemodynamic and tissue perfusion and oxygenation patterns in survivors and nonsurvivors after head injury; to suggest physiologic mechanisms responsible for the observed patterns; and to evaluate postinjury parameters that might be useful for treatment. The hypothesis was that reduced hemodynamics and tissue oxygenation and reduced arterial oxygen saturation affect outcomes.

Study Design: Sixty patients with head trauma were noninvasively monitored on arrival in the emergency department to assess the temporal hemodynamic patterns associated with head injury; patients who were brain dead were excluded because they have very different hemodynamic patterns.

Comparison of chondrocyte apoptosis in vivo and in vitro following acute osteochondral injury.

The objective of the present study was to directly compare levels of chondrocyte apoptosis produced by osteochondral injury in vivo and in vitro. Adult New Zealand White rabbits underwent 2 mm osteochondral drilling of the medial and lateral femoral condyles of a single hind limb. Animals were euthanized, and specimens were harvested at 0, 2, 4, 7, 10, and 14 days following injury.

Acute abdominal pain. Four classifications can guide assessment and management.

Abdominal pain is a common occurrence in older persons and a frequent catalyst for office and emergency room visits. Complaints must be investigated thoroughly because they often indicate serious underlying pathology such as Infection, mechanical obstruction, malignancy, biliary disease, cardiac problems, and GI ischemia. One means of overcoming a sprawling differential diagnosis is to determine whether the problem falls into one of four general categories: peritonitis, bowel obstruction, vascular catastrophe, or nonspecific abdominal pain.