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.

Biomechanical evaluation of sacroiliac joint fixation with decortication.

Background Context: Fusion typically consists of joint preparation, grafting, and rigid fixation. Fusion has been successfully used to treat symptomatic disruptions of the sacroiliac joint (SIJ) and degenerative sacroiliitis using purpose-specific, threaded implants. The biomechanical performance of these systems is important but has not been studied.

Range of motion, sacral screw and rod strain in long posterior spinal constructs: a biomechanical comparison between S2 alar iliac screws with traditional fixation strategies.

Background: S1 screw failure and L5/S1 non-union are issues with long fusions to S1. Improved construct stiffness and S1 screw offloading can help avoid this. S2AI screws have shown to provide similar stiffness to iliac screws when added to L3-S1 constructs.

Morphologic and biomechanical comparison of spinous processes and ligaments from scoliotic and kyphotic patients.

The spinous processes and supraspinous and interspinous ligaments (SSL and ISL, respectively) limit flexion and may relate to spinal curvature. Spinous process angles and mechanical properties of explanted human thoracic posterior SSL/ISL complexes were compared for scoliosis (n=14) vs. kyphosis (n=8) patients.

Flexibility and fatigue evaluation of oblique as compared with anterior lumbar interbody cages with integrated endplate fixation.

Objective: This study was undertaken to quantify the in vitro range of motion (ROM) of oblique as compared with anterior lumbar interbody devices, pullout resistance, and subsidence in fatigue.

Methods: Anterior and oblique cages with integrated plate fixation (IPF) were tested using lumbar motion segments. Flexibility tests were conducted on the intact segments, cage, cage + IPF, and cage + IPF + pedicle screws (6 anterior, 7 oblique).

Biomechanical effect of transforaminal lumbar interbody fusion and axial interbody threaded rod on range of motion and S1 screw loading in a destabilized L5-S1 spondylolisthesis model.

Study Design: A cadaveric lumbosacral spondylolytic spondylolisthesis model was used to evaluate the biomechanical function of 2 different interbody spacers.

Objective: To analyze and compare the reduction in pedicle screw strain and spine range of motion (ROM) between transforaminal lumbar interbody fusion (TLIF) and an axial interbody threaded rod (AxialITR) in a destabilized L5-S1 spondylolisthesis model.

Summary Of Background Data: Symptomatic spondylolytic spondylolisthesis is often treated with posterior instrumented fusion augmented by a variety of different interbody devices.

Compressive properties of fibrous repair tissue compared to nucleus and annulus.

The wound healing process includes filling the void between implant and tissue edges by collagenous connective repair tissue. This fibrous repair tissue may load share or stabilize implants such as spinal disc replacements. The objective of this study was the biomechanical characterization of human fibrous tissue compared to annulus fibrosus and nucleus pulposus.

Validation of an improved method to calculate the orientation and magnitude of pedicle screw bending moments.

Previous methods of pedicle screw strain measurement have utilized complex, time consuming methods of strain gauge application, experience high failure rates, do not effectively measure resultant bending moments, and cannot predict moment orientation. The purpose of this biomechanical study was to validate an improved method of quantifying pedicle screw bending moment orientation and magnitude. Pedicle screws were instrumented to measure biplanar screw bending moments by positioning four strain gauges on flat, machined surfaces below the screw head.

Biomechanical comparison of tibial nail stability in a proximal third fracture: do screw quantity and locked, interlocking screws make a difference?

Objectives: This study compared the fatigue life of nailed proximal third tibial fractures stabilized with either three or four proximal screws using commercially available nails with both locked (through threaded holes or end caps) and nonlocked proximal interlocking screw configurations.

Methods: Eight paired and two independent tibiae of known bone mineral density were acquired, divided into three groups, and implanted with three different commercially available nails (n = 6/group). Nails were all 10 mm in diameter and individually sized for length.

How much do locked screws add to the fixation of "hybrid" plate constructs in osteoporotic bone?

Background: Hybrid locked plating has become a commonly used technique for treating complex fractures and nonunions, but information is lacking to direct the specific application of this fixation method. The purpose of this study was to determine the effect of the number and location of locked screws on the mechanical properties of hybrid plate constructs in an osteoporotic bone model.

Methods: A synthetic commercial composite model of osteoporotic bone with a 5-mm simulated fracture gap was fixed with a 12-hole plate.

No effect of autologous growth factors (AGF) around ungrafted loaded implants in dogs.

Autologous growth factors (AGF) is a growth-factor-rich concentrate of platelets, white blood cells and fibrinogen. Application of AGF was presumed to improve implant fixation and gap healing of non-grafted, loaded implants. We inserted one loaded titanium implant intra-articularly in each medial femoral condyle of eight dogs.