A Dynamic Ankle Orthosis Reduces Tibial Compressive Force and Increases Ankle Motion Compared With a Walking Boot.

Purpose: Tibial bone stress injuries are a common overuse injury among runners and military cadets. Current treatment involves wearing an orthopedic walking boot for 3 to 12 wk, which limits ankle motion and leads to lower limb muscle atrophy. A dynamic ankle orthosis (DAO) was designed to provide a distractive force that offloads in-shoe vertical force and retains sagittal ankle motion during walking.

Impact of a dynamic ankle orthosis on acute pain and function in patients with mechanical foot and ankle pain.

Background: Over two million Americans visit the doctor each year for foot and ankle pain stemming from a degenerative condition or injury. Ankle-foot orthoses can effectively manage symptoms, but traditional designs have limitations. This study investigates the acute impact of a novel "dynamic ankle-foot orthosis" ("orthosis") in populations with mechanical pain (from motion or weight-bearing).

Biomechanical Comparison of a New Dynamic Ankle Orthosis to a Standard Ankle-Foot Orthosis During Walking.

Patients who sustain irreversible cartilage damage or joint instability from ankle injuries are likely to develop ankle osteoarthritis (OA). A dynamic ankle orthosis (DAO) was recently designed with the intent to offload the foot and ankle using a distractive force, allowing more natural sagittal and frontal plane ankle motion during gait. To evaluate its efficacy, this study compared ankle joint kinematics and plantar pressures among the DAO, standard double upright ankle-foot orthosis (DUAFO), and a nonorthosis control (CON) condition in healthy adults during walking.

A mechanical analog thoracolumbar spine model for the evaluation of scoliosis bracing technology.

Introduction: Thoracolumbar braces are used to treat Adolescent Idiopathic Scoliosis. The objective of this study was to design and validate a mechanical analog model of the spine to simulate a thoracolumbar, single-curve, scoliotic deformity in order to quantify brace structural properties and corrective force response on the spine.

Methods: The Scoliosis Analog Model used a linkage-based system to replicate 3D kinematics of spinal correction observed in the clinic.

Mechanical Testing of a Novel Fastening Device to Improve Scoliosis Bracing Biomechanics for Treating Adolescent Idiopathic Scoliosis.

Velcro fastening straps are commonly used to secure a scoliosis brace around the upper body and apply corrective forces to the spine. However, strap loosening and tension loss have been reported that reduce spinal correction and treatment efficacy. A novel fastening device, or controlled tension unit (CTU), was designed to overcome these limitations.

A novel distractive and mobility-enabling lumbar spinal orthosis.

Purpose: Lumbar spinal orthoses are often used as non-surgical treatment and serve to support the spine and alleviate low back pain. More recently, dynamic orthoses claiming to decompress the spine have been introduced. A previously developed prototype of dynamic mobility orthosis (DMO1) was designed that provided a distractive load across the lumbar spine but required higher sagittal bending moments and was unable to maintain spinal off-loading throughout extended ranges of movement.

Development of a Robotic Assembly for Analyzing the Instantaneous Axis of Rotation of the Foot Ankle Complex.

Ankle instantaneous axis of rotation (IAR) measurements represent a more complete parameter for characterizing joint motion. However, few studies have implemented this measurement to study normal, injured, or pathological foot ankle biomechanics. A novel testing protocol was developed to simulate aspects of in vivo foot ankle mechanics during mid-stance gait in a human cadaveric specimen.

Biomechanical Comparison of Robotically Applied Pure Moment, Ideal Follower Load, and Novel Trunk Weight Loading Protocols on L4-L5 Cadaveric Segments during Flexion-Extension.

Background: Extremely few in-vitro biomechanical studies have incorporated shear loads leaving a gap for investigation, especially when applied in combination with compression and bending under dynamic conditions. The objective of this study was to biomechanically compare sagittal plane application of two standard protocols, pure moment (PM) and follower load (FL), with a novel trunk weight (TW) loading protocol designed to induce shear in combination with compression and dynamic bending in a neutrally potted human cadaveric L4-L5 motion segment unit (MSU) model. A secondary objective and novelty of the current study was the application of all three protocols within the same testing system serving to reduce artifacts due to testing system variability.

Bone morphology in 46 BXD recombinant inbred strains and femur-tibia correlation.

We examined the bone properties of BXD recombinant inbred (RI) mice by analyzing femur and tibia and compared their phenotypes of different compartments. 46 BXD RI mouse strains were analyzed including progenitor C57BL/6J (n = 16) and DBA/2J (n = 15) and two first filial generations (D2B6F1 and B6D2F1). Strain differences were observed in bone quality and structural properties (P < 0.

Talonavicular joint fixation: a biomechanical comparison of locking compression plates and lag screws.

Background: Fusion of the talonavicular (TN) joint is an effective treatment for hindfoot pain and deformity. Nonunion in hindfoot fusion procedures is most common in the TN joint. The purpose of this study was to evaluate and compare the mechanical stability of 2 different forms of fixation for isolated fusion of the TN joint.

The influence of fixed sagittal plane centers of rotation on motion segment mechanics and range of motion in the cervical spine.

The center of rotation (CoR) has become an increasingly used metric for biomechanical evaluation of spinal joints however traditional methods of determination remain prone to high degrees of uncertainty. The objective was to use a novel robotic testing protocol to investigate the effects of placement of fixed CoRs in the cervical spine. Human cadaveric C4-C5 (n=3) and C6-C7 (n=5) motion segment units (MSU) were rotated in flexion-extension to limits of 2.

Biomechanical comparison of a novel C1 posterior locking plate with the harms technique in a C1-C2 fixation model.

Study Design: A biomechanical testing protocol was used to study atlantoaxial fixation techniques in a human cadaveric model.

Objective: To compare the in vitro biomechanics of locking plate fixation of the posterior arch of C1 to C2 laminar screw fixation, with that of conventional C1 lateral mass to C2 pars screw fixation.

Summary Of Background Data: Current methods of atlantoaxial fixation pose a risk to neurologic and vascular structures.

Biomechanical testing of a novel four-rod technique for lumbo-pelvic reconstruction.

Study Design: A biomechanical testing protocol was used to study different lumbo-pelvic fixation techniques in a human cadaveric lumbar spine model.

Objective: To compare the in vitro biomechanics of a novel four-rod lumbo-pelvic reconstruction technique with and with out cross-links, to that of a conventional cross-linked two-rod technique.

Summary Of Background Data: Numerous lumbo-pelvic reconstruction methods based on the Galveston two-rod technique have been proposed for cases involving total sacrectomy.

A biomechanical study of artificial cervical discs using computer simulation.

Study Design: A virtual simulation model of the subaxial cervical spine was used to study the biomechanical effects of various disc prosthesis designs.

Objective: To study the biomechanics of different design features of cervical disc arthroplasty devices.

Summary Of Background Data: Disc arthroplasty is an alternative approach to cervical fusion surgery for restoring and maintaining motion at a diseased spinal segment.

Biomechanical testing simulation of a cadaver spine specimen: development and evaluation study.

Study Design: This article describes a computer model of the cadaver cervical spine specimen and virtual biomechanical testing.

Objectives: To develop a graphics-oriented, multibody model of a cadaver cervical spine and to build a virtual laboratory simulator for the biomechanical testing using physics-based dynamic simulation techniques.

Summary Of Background Data: Physics-based computer simulations apply the laws of physics to solid bodies with defined material properties.

Motion compensation associated with single-level cervical fusion: where does the lost motion go?

Study Design: Seven adult human cadaveric cervical spines (C2-T1) were biomechanically tested in a programmable testing device.

Objective: Compare the effects of incremental single-level fusion at different levels of the cervical spine.

Summary Of Background Data: Clinical studies have reported degenerative symptomatic disc disease at disc levels adjacent to fusion.

Cervical spine arthroplasty biomechanics.

The advent of cervical intervertebral disc replacement represents an exciting and new frontier in the treatment of myelopathy and discogenic pain. The goal of most disc arthroplasty designs is to attempt to approximate the normal spinal motion as much as possible. This survey article provides a general overview as to the goals of cervical disc replacement, the current state of knowledge concerning how these devices have been evaluated, and a commentary on future work that should be performed to characterize these devices fully.

In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant.

An in vitro biomechanical study was conducted to compare the effects of disc arthroplasty and anterior cervical fusion on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level cervical disc arthroplasty, and single-level fusion. A programmable testing apparatus was used that replicated physiological flexion/extension, lateral bending, and axial rotation.

An improved biomechanical testing protocol for evaluating spinal arthroplasty and motion preservation devices in a multilevel human cadaveric cervical model.

Object: An experimental study was performed to determine the biomechanical end-mounting configurations that replicate in vivo physiological motion of the cervical spine in a multiple-level human cadaveric model. The vertebral motion response for the modified testing protocol was compared to in vivo motion data and traditional pure-moment testing methods.

Methods: Biomechanical tests were performed on fresh human cadaveric cervical spines (C2-T1) mounted in a programmable testing apparatus.

Biomechanical testing of an artificial cervical joint and an anterior cervical plate.

An in vitro biomechanical study was conducted to determine the effects of fusion and nonfusion anterior cervical instrumentation on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level artificial cervical joint, and single-level graft with anterior cervical plate. A programmable testing apparatus was used that replicated physiologic flexion/extension and lateral bending.

Biomechanical evaluation of flexor tendon function after hamate hook excision.

Purpose: Hamate hook fractures are uncommon injuries for which treatment is controversial. Excision of the hamate hook is considered to be the preferred method of treatment but the effects of hamate excision are not clearly delineated. The purpose of this study was to determine what effect, if any, excision of the hamate has on flexor tendon function.

Bioabsorbable anterior lumbar plate fixation in conjunction with cage-assisted anterior interbody fusion.

Object: An in vitro biomechanical study was conducted to determine the effects of anterior stabilization on cage-assisted lumbar interbody fusion biomechanics in a multilevel human cadaveric lumbar spine model.

Methods: Three spine conditions were compared: harvested, bilateral multilevel cages (CAGES), and CAGES with bioabsorbable anterior plates (CBAP), tested under flexion-extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending/rotational moments.

Bioabsorbable anterior lumbar plate fixation in conjunction with anterior interbody fusion cages.

An in vitro biomechanical study was conducted to determine the effects of anterior stabilization on lumbar interbody cage fusion biomechanics in a multilevel human cadaveric lumbar model. Three spine conditions were compared: harvested, bilateral multilevel cages (CAGES), and CAGES with bioabsorbable anterior plates (CBAP), tested under flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending/rotational moments.