Development of a sacral fracture model to demonstrate effects on sagittal alignment.

Purpose: To develop a modeling framework to predict the secondary consequences on spinal alignment following correction and to demonstrate the impact of pedicle subtraction osteotomy (PSO) location on sagittal alignment.

Methods: Six patients were included, and pelvic incidence (PI) was measured. Full-length standing radiographs were uploaded into PowerPoint and manipulated to model S1-S2 joint line sacral fractures at 15°, 20°, 25°, and 30°.

An MCL internal brace can withstand cyclic fatigue loading and produce a valgus load to failure similar to that of intact knees.

Purpose: The purpose of this study is to report on the biomechanical durability and strength of an MCL internal brace construct. The null hypothesis is that there will be no difference between this construct and the intact MCL in terms of deflection during fatigue testing and the ultimate failure load.

Methods: Eight cadaver knees were used.

MCL internal brace does not fully recapitulate normal MCL function in valgus stress.

Purpose: The null hypothesis is that there would be no difference in medial gapping under valgus load between the intact MCL and the ruptured MCL with an internal brace in place.

Methods: Eight pairs of cadaver knees were used (16 knees). Alternating sides, one knee from each pair was used for one of two "internal brace" constructs.

Culture and characterization of various porcine integumentary-connective tissue-derived mesenchymal stromal cells to facilitate tissue adhesion to percutaneous metal implants.

Background: Transdermal osseointegrated prosthesis have relatively high infection rates leading to implant revision or failure. A principle cause for this complication is the absence of a durable impervious biomechanical seal at the interface of the hard structure (implant) and adjacent soft tissues. This study explores the possibility of recapitulating an analogous cellular musculoskeletal-connective tissue interface, which is present at naturally occurring integumentary tissues where a hard structure exits the skin, such as the nail bed, hoof, and tooth.

Biomechanical Stability of the Sacroiliac Joint with Differing Implant Configurations in a Synthetic Model.

Background: The sacroiliac joint (SIJ) is responsible for 15%-30% of chronic low back pain and fusion is increasingly used to alleviate chronic SIJ pain in adults. However, questions remain as to the most effective implant patterns to stabilize the joint. The objective of this biomechanical study was to evaluate how different implant spacing, configuration and quantity effect range of motion (ROM) of a synthetic foam SIJ model.

Augmentation of implant surfaces with BMP-2 in a revision setting : effects of local and systemic bisphosphonate.

Aims: We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants.

Methods: An established allografted revision protocol was implemented bilaterally into the stifle joints of 24 canines. At revision surgery, each animal received one BMP-2 (5 µg) functionalized implant, and one raw implant.

A Vision for Using Simulation & Virtual Coaching to Improve the Community Practice of Orthopedic Trauma Surgery.

Background: Many orthopedic surgeries involve the challenging integration of fluoroscopic image interpretation with skillful tool manipulation to enable procedures to be performed through less invasive approaches. Simulation has proved beneficial for teaching and improving these skills for residents, but similar benefits have not yet been realized for practicing orthopedic surgeons. A vision is presented to elevate community orthopedic practice and improve patient safety by advancing the use of simulators for training and assessing surgical skills.

Compartment Syndrome: Evaluation of Skeletal Muscle Ischemia and Physiologic Biomarkers in Controlled Conditions Within Ex Vivo Isolated Muscle Bundles.

Objectives: To identify potential physiologic markers of muscle ischemia to serve as diagnostic indicators of compartment syndrome. We hypothesize that muscle bundles in hypoxic conditions will elicit decreases in potential hydrogen (pH) and increases in lactate and potassium that correlates with decreased muscle twitch forces.

Methods: We performed an ex vivo evaluation of individual skeletal muscle bundles obtained from a swine's diaphragm that were exposed to hypoxic conditions and compared with control groups.

Orthopaedic osseointegration: Implantology and future directions.

Osseointegration (OI) is the direct anchorage of a metal implant into bone, allowing for the connection of an external prosthesis to the skeleton. Osseointegration was first discovered in the 1960s based on the microscopic analysis of titanium implant placed into host bone. New bone was observed to attach directly to the metal surface.

Mechanical Performance of Posterior Spinal Instrumentation and Growing Rod Implants: Experimental and Computational Study.

Study Design: Experimental and computational study of posterior spinal instrumentation and growing rod constructs per ASTM F1717-15 vertebrectomy methodology for static compressive bending.

Objective: Assess mechanical performance of standard fusion instrumentation and growing rod constructs.

Summary Of Background Data: Growing rod instrumentation utilizes fewer anchors and spans longer distances, increasing shared implant loads relative to fusion.

Predicting the Effect of Bilateral Pelvic Osteotomy on Sagittal Alignment Correction and Surrounding Muscles: A Mathematical Model.

Mathematical Model. To investigate the relationship between pelvic osteotomy opening angle (OA) and its effect on spinopelvic sagittal parameters as well as the resting length of surrounding muscles. Predictive equations correlating OA with spinopelvic parameters were derived using geometric relationships.

A biomechanical study comparing minimally invasive anterior pelvic ring fixation techniques to external fixation.

Introduction: INFIX and Pelvic Bridge are two new minimally invasive surgical techniques for unstable pelvic ring injuries, and they have demonstrated early clinical success in small, single-center case-series. The primary objective of this study is to gather evidence speaking to the biomechanical stability of internal bridging methods relative to external fixation, with the expectation of biomechanical equivalence.

Methods: Ten human cadaveric pelvic specimens were dissected free of all skin, fat, organs, and musculature and were prepared with a partially unstable pelvic ring injury (OTA/AO 61-B).

Robust variational segmentation of 3D bone CT data with thin cartilage interfaces.

We present a two-stage variational approach for segmenting 3D bone CT data that performs robustly with respect to thin cartilage interfaces. In the first stage, we minimize a flux-augmented Chan-Vese model that accurately segments well-separated regions. In the second stage, we apply a new phase-field fracture inspired model that reliably eliminates spurious bridges across thin cartilage interfaces, resulting in an accurate segmentation topology, from which each bone object can be identified.

Examination of Skill Acquisition and Grader Bias in a Distal Radius Fracture Fixation Model.

Objectives: Primary: Assess the ability of faculty graders to predict the objectively measured strength of distal radius fracture fixation. Secondary: Compare resident skill variation and retention related to other knowable training data.

Design: Residents were allowed 60 minutes to stabilize a standardized distal radius fracture using an assigned fixed-angle volar plate.

Dose-Dependent Resorption of Allograft by rhBMP-2 Uncompensated by New Bone Formation-A Canine Study With Implants and Zoledronate.

Background: Impacted bone allograft is used to restore lost bone in total joint arthroplasties. Bone morphogenetic proteins (BMPs) can induce new bone formation to improve allograft incorporation, but they simultaneously invoke a seemingly dose-dependent allograft resorption mediated by osteoclasts. Bisphosphonates effectively inhibit osteoclast activity.

The Pursuit of Scholarship: Why We Should Care About Resident Research.

Research is a foundational component of an orthopaedic residency. It fosters intellectual curiosity and pursuit of excellence, while teaching discipline and the scientific method. These are the key principles for careers in both community-based practice and academia.

Healing in peri-implant gap with BMP-2 and systemic bisphosphonate is dependent on BMP-2 dose-A canine study.

The bone-implant interface of cementless orthopedic implants can be described as a series of uneven sized gaps with discontinuous areas of direct bone-implant contact. Bridging these voids and crevices by addition of an anabolic stimulus to increase new bone formation can potentially improve osseointegration of implants. Bone morphogenetic protein 2 (BMP-2) stimulates osteoblast formation to increase new bone formation but also indirectly stimulates osteoclast activity.

Tobacco exposure and wound healing in head and neck surgical wounds.

Objective: Smoking impairs wound healing, yet the underlying pathophysiological mechanisms are unclear. We evaluated tobacco-altered healing in head and neck surgery by studying the association between biomarkers and tobacco exposure, as well as cutaneous perfusion by smoking status.

Study Design: Prospective cohort study, tertiary/academic care center, 2011 to present.

The Effect of Surgical Technique and Spacer Texture on Bone Regeneration: A Caprine Study Using the Masquelet Technique.

Background: The Masquelet-induced-membrane technique is a commonly used method for treating segmental bone defects. However, there are no established clinical standards for management of the induced membrane before grafting.

Questions/purposes: Two clinically based theories were tested in a chronic caprine tibial defect model: (1) a textured spacer that increases the induced-membrane surface area will increase bone regeneration; and (2) surgical scraping to remove a thin tissue layer of the inner induced-membrane surface will enhance bone formation.

Do Bone Graft and Cracking of the Sclerotic Cavity Improve Fixation of Titanium and Hydroxyapatite-coated Revision Implants in an Animal Model?

Background: We previously introduced a manual surgical technique that makes small perforations (cracks) through the sclerotic bone shell that typically forms during the process of aseptic loosening ("crack" revision technique). Perforating just the shell (without violating the proximal cortex) can maintain overall bone continuity while allowing marrow and vascular elements to access the implant surface. Because many revisions require bone graft to fill defects, we wanted to determine if bone graft could further increase implant fixation beyond what we have experimentally shown with the crack technique alone.