Biomechanical Comparison of Two Surgical Repair Techniques of the Distal Biceps Tendon.

Purpose: This study aimed to characterize the relationship between the distal biceps tendon force and the supination and flexion rotations during the initiation phase and to compare the functional efficiency of anatomic versus nonanatomic repairs.

Methods: Seven matched pairs of fresh-frozen cadaver arms were dissected to expose the humerus and elbow while preserving the biceps brachii, elbow joint capsule, and distal radioulnar soft tissue complex. For each pair, the distal biceps tendon was severed with a scalpel and then repaired with bone tunnels placed at either the anterior (anatomic) or the posterior (nonanatomic) aspect of the bicipital tuberosity on the proximal radius.

Biomechanical Evaluation of Transverse Patella Fracture Fixation Using Headless Screws: A Comparison of Suture Versus Cable as a Tension Band.

Objectives: To explore the performance of headless screws with FiberWire Suture as a tension band and headless screws with a mini-cable tension band in patella fixation.

Methods: A transverse osteotomy was created in 6 matched pairs of fresh-frozen cadaver knee joints. One knee was randomly assigned to receive fixation with headless screws plus a cable tension band while the other was fixed with headless screws plus a suture tension band.

Effect of age on femur whole-bone bending strength of mature rat.

Background: Skeletally mature rodents are frequently used in studies of bone health and bone healing, some of them requiring longitudinal observations that span a significant portion of the animals' adulthood. However, changes in whole bone mechanics associated with the natural aging of adult rats have not been extensively characterized.

Methods: Femurs from skeletally mature Wistar rats in three age groups of 24-week (young adult), 39-week (middle-age), and 54-week (late middle-age) were tested under three-point bending load in the anterior-posterior direction.

Biomechanical Comparison of Tension Band Fixation of Patella Transverse Fracture: Headless Screws Versus Headed Screws.

Objective: This study aimed to investigate the stability and strength of tension band wire fixation using headless compression screws versus headed screws for transverse patella fractures.

Methods: Six matched pairs of fresh-frozen cadaveric knees with transverse osteotomies created at the midpoint of the patella were surgically fixed, with one knee randomly receiving fixation with headless screws (Acumed Acutrak 4/5) and the other with headed screws (Synthes 4.0 partially threaded cannulated screws).

Assessment of Mechanical Characteristics of Ankle-Foot Orthoses.

Recent designs of ankle-foot orthoses (AFOs) have been influenced by the increasing demand for higher function from active individuals. The biomechanical function of the individual and device is dependent upon the underlying mechanical characteristics of the AFO. Prior mechanical testing of AFOs has primarily focused on rotational stiffness to provide insight into expected functional outcomes; mechanical characteristics pertaining to energy storage and release have not yet been investigated.

Biomechanical comparison of supplemental posterior fixations for two-level anterior lumbar interbody fusion.

Posterior instrumentations have been used to supplement anterior lumbar interbody fusion with cages. Biomechanical studies on single-level anterior lumbar interbody fusion show that stand-alone cages supplemented with posterior translaminar facet or transfacet screw fixation exhibit comparable stability to those supplemented with pedicle screw/rod fixation, while stability of multilevel anterior lumbar interbody fusion remains mostly unknown. The objectives of this study are to compare the stabilization of three supplemental posterior fixations to two-level anterior lumbar interbody fusion, including translaminar facet fixation, transfacet screw fixation, and pedicle screw/rod fixation.

Evaluation of cast creep occurring during simulated clubfoot correction.

The Ponseti method is a widely accepted and highly successful conservative treatment of pediatric clubfoot involving weekly manipulations and cast applications. Qualitative assessments have indicated the potential success of the technique with cast materials other than standard plaster of Paris. However, guidelines for clubfoot correction based on the mechanical response of these materials have yet to be investigated.

The effect of dynamic femoroacetabular impingement on pubic symphysis motion: a cadaveric study.

Background: A link between femoroacetabular impingement and athletic pubalgia has been reported clinically. One proposed origin of athletic pubalgia is secondary to repetitive loading of the pubic symphysis, leading to instability and parasymphyseal tendon and ligament injury. Hypothesis/

Purpose: The purpose of this study was to investigate the effect of simulated femoral-based femoroacetabular impingement on rotational motion at the pubic symphysis.

Alteration of load sharing of anterior cervical implants with change in cervical sagittal alignment.

Anterior cervical discectomy and fusion (ACDF) is often supplemented with the application of an anterior plate to improve the stability of the fusion segment. While plate design has been shown to influence stress shielding of the graft, little is known about how the kyphotic alignment of a fused cervical segment affects the load sharing between the anterior plate and the osteoligamentous structures of the spine. The aim of this study was to characterize load sharing between an anterior plate and the osteoligamentous structures of the cervical motion segments in kyphotic versus normal lordotic alignment following single-level ACDF using fresh ovine cervical spines (C3-C6).

Changes in the lumbar foramen following anterior interbody fusion with tapered or cylindrical cages.

Background Context: Anterior lumbar interbody fusion (ALIF) using both cylindrical and tapered threaded interbody cages has been shown to restore disc height, reduce segmental motion, and relieve low back pain. The effectiveness of these stand-alone cage designs in restoration and maintenance of intervertebral foraminal dimensions has received little attention.

Purpose: To investigate the effects of anterior implantation of cylindrical and tapered interbody cages on morphologic changes of the lumbar neuroforamen and maintenance of foraminal dimensions under dynamic loading.

Biomechanical comparison of fixed-angle volar plate versus fixed-angle volar plate plus fragment-specific fixation in a cadaveric distal radius fracture model.

Purpose: To test the hypothesis that combining orthogonal fragment-specific fixation with volar fixed-angle fixation provides markedly higher interfragment stability and construct strength compared with volar fixed-angle fixation alone.

Methods: Eight matched pairs of fresh cadaveric hand and forearm specimens were potted upright in cement. Flexor and extensor tendons were isolated at insertion sites and sutured into a looped bundle for loading in flexion and extension, respectively (up to 61 N).

Does anterior plating of the cervical spine predispose to adjacent segment changes?

Study Design: In a human cadaveric model, the effects of plate supplementation on the mechanical behaviors of adjacent segments were investigated.

Objectives: The objective was to determine the effects of anterior cervical fusion and plating on the adjacent segments.

Summary Of Background Data: Increases in intradiscal pressure and intervertebral motion at adjacent segments have been reported in the lumbar spine following an instrumented fusion.

Mechanical evaluation of posterior wiring as a supplement to anterior cervical plate fixation.

Study Design: An in vitro experimental study was performed to examine 3-dimensional biomechanical stability of cervical fixations.

Objectives: To determine whether posterior interspinous wiring contributes to the rigidity of a single-level motion segment that has been plated anteriorly, and to determine the effects of this combined fixation on intradiscal pressure and spinal motion at the adjacent segments.

Summary Of Background Data: Combined anterior and posterior column fixation is being increasingly used in a variety of clinical situations that do not involve complete disruption of the motion segment.

Intradiscal pressure and kinematic behavior of lumbar spine after bilateral laminotomy and laminectomy.

Background Context: Bilateral laminotomy has been proposed as an alternative to laminectomy for decompression of lumbar spinal stenosis. Preservation of the posterior midline ligaments with laminotomy is presumed to maintain spinal segment stability. There have been no previous studies that directly compare the amount of destabilization and increase in disc pressures between the two procedures.

Effects of trunk position on back surface-contour measured by raster stereophotography.

A study of the contour of the surface of the back was conducted using the Quantec spinal image system (QSIS; raster stereophotography) and the Vicon 3-dimensional (3-D) motion analysis system with a plaster model of the scoliotic spine. With postural changes in 3 dimensions came alterations in the surface shape of the back. Most changes in QSIS parameters occurred in the coronal plane.