Relationship Between Ulnar Variance, Cortical Bone Density, and Load to Failure in the Distal Radius at the Typical Site of Fracture Initiation.

Purpose: Increased ulnar variance has been shown to lead to diminished load borne by the distal radius. The purpose of this study was to determine the correlations among ulnar variance, bone mineral density, and load to failure at the distal radius.

Methods: Posteroanterior radiographs and computed tomographic scans were taken of 12 cadaveric forearms in neutral rotation.

Incidence of Patients With Knee Strain and Sprain Occurring at Sports or Recreation Venues and Presenting to United States Emergency Departments.

Context: Knee injuries account for a substantial percentage of all athletic injuries. The relative rates of knee injury for a variety of sports by sex and age need to be understood so we can better allocate resources, such as athletic trainers, to properly assess and treat injuries and reduce injury risk.

Objective: To describe the epidemiology of patients with sport-related knee strain and sprain presenting to US emergency departments from 2002 to 2011.

Allograft Reconstruction of the Lisfranc Ligament.

Unlabelled: For Lisfranc injuries, screw fixation of the medial and middle columns is currently the standard of treatment. The purpose of this study was to biomechanically evaluate the use of allograft for a severed Lisfranc ligament compared to standard screw fixation and the intact condition. Six pairs of fresh-frozen cadaveric lower extremities were prepared with reflective marker arrays and cyclically loaded to simulate partial weight bearing under 4 sequential testing conditions: (1) intact ligament, (2) disrupted ligament, (3) tendon allograft reconstructed ligament, and (4) rigid screw fixation.

A biomechanical comparison of 2 hybrid techniques for elbow ulnar collateral ligament reconstruction.

Purpose: To compare the valgus laxity and fixation strength of 2 hybrid techniques for elbow ulnar collateral ligament reconstructions.

Methods: Reflective markers were placed near the ligament attachments of the ulnar collateral ligament on the humerus and ulna of 12 fresh-frozen cadaveric upper extremities for tracking displacement with 4 motion analysis cameras. Valgus laxity testing was performed on the intact, disrupted ligament, and reconstructed elbows by applying a 3.

Biomechanical comparison of first metatarsophalangeal joint arthrodeses using triple-threaded headless screws versus partially threaded lag screws.

Background: Triple-threaded, cannulated headless screws of varying thread diameters and pitch are designed to maintain thread length across the arthrodesis plane, provide joint compression, and reduce countersinking. This study tested the biomechanical fixation strength of conventional partially threaded lag screws compared to triple-threaded headless screws in first metatarsophalangeal joint arthrodesis.

Methods: First metatarsophalangeal joint arthrodesis using a crossed screw technique was performed on 11 paired, preserved cadaver first rays with two 4.

Three-dimensional computed tomography-based modeling of sagittal cadaveric femoral bowing and implications for intramedullary nailing.

Objectives: To establish the nature and extent of femur sagittal bowing by determining outer and inner anterior cortex geometries and sizes using analytical 3-dimensional computed tomography modeling and relate the resultant femoral curvature with the curvatures of available intramedullary nails.

Methods: Computed tomography scans were rendered in 3D using modeling software to reconstruct 2 geometries: (1) outer cortex and (2) medullary canal. Femoral bow in the sagittal plane and the anterior cortical thickness were measured.

Fixation strength of anteriorly inserted headless screws for talar neck fractures.

Background: For noncomminuted talar neck fractures, traditional fixation is with small fragment screws or cannulated screws. Newer screw systems on the market allow placement of cannulated headless screws, which provide compression by virtue of a variable-pitch thread. The headless construct has an inherent advantage, particularly for the talus, when the screws must be countersunk to prevent wear of the joint articular surfaces.

Specimen specific, 3D modeling of the elbow--prediction of strain in the medial collateral ligament.

In this project 3D interactive models of twelve cadaver elbows are developed using the author's kinematic simulation software. The effective flexion-extension axes for each specimen's model are iteratively defined based upon congruent joint motion and individual limits in range-of-motion. Origins and insertions of both parts of the medial collateral ligament are digitized following careful dissection of each specimen.

Computer simulation of pectoralis major muscle strain to guide exercise protocols for patients after breast cancer surgery.

Study Design: Descriptive study.

Objectives: To quantify and rank the order of strain (length change in proportion to the resting length) of 3 portions of the pectoralis major (PM) muscle during various exercises.

Background: A biomechanical foundation on which to base exercise prescriptions for patients after breast cancer surgery is lacking.

The sacroiliac spine - computer simulation of motion and modeling of the ligaments.

Using an interactive, 3D, kinematic simulation of the human skeleton, the motion of the sacro-iliac (SI) joint is modeled based upon descriptions available in the literature. The major ligaments are added to the simulation data structure using deformable cubic B-spline curve paths. Ligament strains were generated and studied in response to the motion simulations.

Three femoral fixation devices for anterior cruciate ligament reconstruction: comparison of fixation on the lateral cortex versus the anterior cortex.

Purpose: To evaluate the biomechanical properties of 3 anterior cruciate ligament (ACL) reconstruction femoral fixation devices in a porcine model with implantation on both the lateral femoral cortex and the anterior femoral cortex.

Methods: ACL reconstructions with an 8-mm porcine tendon graft were performed on 48 porcine femurs with the EndoButton CL (Smith & Nephew, Andover, MA), ToggleLoc with ZipLoop technology (Biomet Sports Medicine, Warsaw, IN), or EZLoc (Biomet Sports Medicine). In 8 specimens for each implant, the femoral tunnel was drilled from the 10:30 surgical position out the lateral cortex.

The effect of modern total knee arthroplasty on muscle balance at the knee.

Total Knee Arthroplasty (TKA) may affect the muscles operating at the flexion/extension (FE) or internal /external rotation (IE) axes. This study tested the hypothesis that a modern posterior stabilizing TKA will change the mechanical balance of the knee joint by altering the moment arms of muscles acting about two separate axes of rotation. Moment arms were determined for the normal knee, the knee after resection of the Anterior Cruciate Ligament (the ACL - knee) and the knee after a PCL-sacrificing TKA.

Use of a patient-controlled stretching device to improve the ankle range of motion.

Background: Ankle and subtalar stiffness are widely associated with many foot and ankle conditions and functional deficits. Loss of range of motion, particularly dorsiflexion, results in significant gait dysfunction. A variety of methods have been evaluated to address this problem, including yoga, manipulation, dance training, jogging and static stretching exercises.

Tensioning of anterior cruciate ligament hamstring grafts: comparing equal tension versus equal stress.

Purpose: A biomechanical study was undertaken to determine whether equal-stress or equal-tension tensioning of anterior cruciate ligament 4-stranded semitendinosus and gracilis grafts provides a stronger graft construct when testing to ultimate failure.

Methods: Eighteen fresh-frozen cadaveric semitendinosus and gracilis tendons were each positioned over a cylinder rod/cryo-clamp connected to an MTS machine (MTS Systems, Eden Prairie, MN) by another cryo-clamp. In the equal-tension group the 4 strands were equally tensioned by weights.

Upper-limb kinematics of the presumed-to-be-unaffected side after brain injury.

Objective: The purpose of this pilot study was to investigate the kinematics of the presumed-to-be-unaffected upper limbs of people with brain injury (BI) compared with people without brain injury (WBI) during reaching.

Method: Seventeen people with BI with no apparent motor deficit and 17 people WBI were measured and compared. A six-camera motion analysis system was used to determine movement duration, average speed, and smoothness during reaching.

Osteoformin accelerates fresh fracture healing in rats.

Purpose: Negatively charged resins have been shown to stimulate bone repair. In previous studies, the negatively charged polypeptide polyaspartate, which has been named Osteoformin, has been shown to stimulate osteoblast differentiation in vitro. The objective of the current study was to investigate the potential effect of Osteoformin on experimental femoral fracture healing in vivo.

Geometry-based algorithm for the prediction of nonpathologic mandibular movement.

Purpose: The goal of this study was to create a model for human mandibular movement prediction based on the geometry of the mandible.

Materials And Methods: Ten nonpathologic individuals underwent motion tracking and sagittal radiographs. From the data, a mathematical algorithm for mandibular movement prediction was developed based on mandibular geometry.

Modeling avian kinematics using software developed for the human musculoskeletal system.

Using an interactive computer graphic system developed for the simulation of human musculoskeletal kinematics and detailed Computerized Tomography (CT) imaging of the domestic turkey, a kinematic structure of the avian trunk and wings is defined. The result is a simulation that provides interactive study of avian muscle-tendon joint kinematics, the ability to elucidate the essential components of bird flight and visual verification of heuristic muscle-tendon-joint models through real-time, 3D interaction. This application demonstrates the flexibility and applicability of this simulation software to define the kinematic structure of any animal or robotic mechanism given a segmented, 3D skeletal structure and to define the necessary and sufficient joints (linked revolutes and degrees-of-freedom) and muscle-tendon paths for that animal.

A system for measurement and calibration of nonorthogonal joints and limbs in humans.

Human limbs are a multilinked system in which the revolute joints are not orthogonal to the limb segments or to each other. The standard method for movements of multilinked systems is the Denavit-Hartenberg (DH) representation, which is useful for orthogonal systems. When applied to non-orthogonal systems, the DH representation projects the reference frames outside of the limb segments.

Predicting moment arms in diarthroidal joints - 3D computer simulation capability and muscle-tendon model validation.

Interactive 3D simulation of musculoskeletal kinematics is used to predict the instantaneous moment arms of muscles acting about joints. Experimental studies were completed to verify the moment arms of muscles in the finger joints and at the knee. For other joints, predictions were compared with studies from the literature.

Three-dimensional analysis of the ligamentous attachments of the second through fifth carpometacarpal joints.

The purpose of this study is to clarify, measure, and show the anatomic locations and areas of specific ligamentous attachments and paths of the second through fifth carpometacarpal (CMC) joints on a three-dimensional (3D) surface model. Ten fresh-frozen cadaver wrists were used to dissect and identify the second through fifth CMC ligaments. Their ligamentous attachments and whole bone surfaces were digitized three-dimensionally and their areas calculated.

Three-dimensional analysis of the ligamentous attachments of the first carpometacarpal joint.

Purpose: To show the ligamentous locations and attachments of the first carpometacarpal (CMC) joint on a 3-dimensional (3-D) surface model.

Methods: Ten fresh-frozen cadaver wrists were used to dissect and identify the first CMC ligaments. Their ligamentous attachments and whole bone surfaces were digitized 3-dimensionally and their areas were calculated.

Intrinsic muscle contribution to the metacarpophalangeal joint flexion moment of the middle, ring, and small fingers.

Purpose: To analyze the relative contribution of the intrinsic muscles to the flexion moment potential of the metacarpophalangeal (MCP) joints of the middle, ring, and small fingers and to calculate the moment potential loss occurring with deep motor branch, low, or high ulnar nerve palsy or low median nerve palsy.

Methods: Eleven fresh cadaver hands were used. A small wire sutured to each tendon was connected to an excursion transducer containing a constant-tension spring.

Volar fixation for dorsally angulated extra-articular fractures of the distal radius: a biomechanical study.

Purpose: To compare the biomechanical properties of 10 volar plate-fixation designs in 2 fracture models (dorsal wedge osteotomy, segmental resection osteotomy models).

Methods: Forty-eight radiuses were used in this study including 8 pairs. In 40 specimens a 15-mm dorsally based wedge osteotomy was performed and the volar cortex was fractured manually.