Title of Document: HUMERAL FRACTURE FIXATION TECHNIQUES: A FEA COMPARISON OF LOCKING AND COMPRESSION TECHNIQUES WITH CADAVERIC PULLOUT COMPARISON OF CORTICAL COMPRESSION AND INTERNAL LOCKING SCREWS. Aaron Johnson, MS Mechanical Engineering, 2007 Directed By: Professor, Donald Barker, Mechanical Engineering Locking and non-locking humeral repair techniques provide different mechanical constructs...

BACKGROUND Surgical treatment of rotator cuff tears may be complicated by osteoporosis of the proximal part of the humerus. The purpose of this study was to determine whether pullout strength of suture anchors is affected by the location of the anchor placement and by bone mineral density. We hypothesized that higher bone mineral density is associated with higher pullout strength of suture anch...

A large scale experimental program using vertical and batter model piles in sand subjected to pull out loads has been carried out in a model tank of size 1m x 1m x 1m. Mild steel pipes of varying diameters, lengths, and shapes are used as model piles. A poorly graded river sand having specific gravity G= 2.67, Uniformity coefficient= 3.53, emax = 0.81, emin = 0.54 has been used as foundation me...

Foundations of structures which are subjected to uplift loading require anchoring systems to resist pullout loads. Such anchors can be broadly classified as gravity anchors, pile anchors and plate anchors. Plate anchors can be circular, square or strip in shape. The loading applied on plate anchors can be vertical, inclined or horizontal depending on the anchor orientation. In this study, vario...

OBJECTIVE To compare, using photoelasticity, internal stress produced by USS II type screw with 5.2 and 6.2 mm external diameters, when submitted to three different pullout strengths. METHODS Two photoelastic models were especially made. The simulation was performed using loads of 1.8, 2.4 e 3.3 kgf.The fringe orders were evaluated around the screws. In all the models analyzed the shear stres...

BACKGROUND This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength us...

Study Design Mechanical study. Purpose To compare the pullout strength of different screw designs and augmentation techniques in an osteoporotic bone model. Overview of Literature Adequate bone screw pullout strength is a common problem among osteoporotic patients. Various screw designs and augmentation techniques have been developed to improve the biomechanical characteristics of the bone-...

The effect of simulated early weight bearing on both micromotion and pullout strength of uncemented distal femoral stems was evaluated in this study. The effect of stem endosteal contact and bone quality on implant pullout strength was also analyzed. A randomized matched-pair study was performed using 8 bilateral pairs of fresh human cadaveric femoral specimens. Each specimen pair was dual-ener...

BACKGROUND Orthopaedic surgeons often face clinical situations where improved screw holding power in cancellous bone is needed. Injectable calcium phosphate cements are one option to enhance fixation. METHODS Paired screw pullout tests were undertaken in which human cadaver bone was augmented with calcium phosphate cement. A finite element model was used to investigate sensitivity to screw po...

BACKGROUND Effective soft tissue graft fixation to the tibial tunnel in all-inside anterior cruciate ligament reconstructions has been reported to be a problem and may lead to retrograde pullout at ultimate load testing. HYPOTHESIS A combined retrograde bioabsorbable screw and cortical-cancellous suture button suspension apparatus would gain stiffness from the button and strength from the scr...