During development the central disc contains large, vacuolated notochordal (NC) cells which in humans are replaced by mature nucleus pulposus (NP) cells during aging, but are maintained in certain breeds of dogs. During degeneration the disc becomes less hydrated which affects its normal function. Aquaporins (AQP) are a family of 13 transmembrane channel proteins that allow passage of water and are responsible for maintaining water homeostasis. AQP1, 2, 3 and 5 have been identified in the intervertebral disc (IVD). Here, expression of AQPs in human and canine IVDs to determine expression in NC v/s NP cells and whether expression changes during degeneration. Gene expression of all 13 AQPs, were investigated in 102 human NP samples using RT-qPCR. AQPs which were expressed at gene level were further investigated by Immunohistochemistry in human and canine IVD samples.Introduction
Methods
The intervertebral disc (IVD) is a highly hydrated tissue which is reduced during degeneration leading to loss of function. Aquaporins (AQP) are a family of 13 (AQP0-12) transmembrane channel proteins that selectively allow the passage of water and other small molecules in and out of cells and are responsible for maintaining water homeostasis. AQP1, 2, 3 and 5 have been identified in the IVD. Here gene and protein expression of all 13 AQPs was investigated in a large cohort of human IVDs to investigate expression during IVD degeneration. Gene expression of all 13 AQPs was investigated in non-degenerate and degenerate tissue from 102 human NP samples using RT-qPCR. AQPs which were expressed at gene level were further investigated in 30 IVD samples by Immunohistochemistry.Introduction
Methods
Periprosthetic femoral fractures are a challenging problem to manage. In the literature various constructs have been designed and tested, most requiring cables for proximal fixation. The Synthes Locking Attachment Plate (LAP) has been designed to achieve proximal fixation without the use of cables. The aim of this study was to biomechanically evaluate the LAP construct in comparison to a Cable plate construct, for the fixation of periprosthetic femoral fractures after cemented total hip arthroplasty (THA). Twelve synthetic femora were tested in axial compression, lateral bending and torsion to determine initial stiffness, and stiffness following fixation of a simulated midshaft fracture with and without a bone gap. Two different fracture fixation constructs (six per group) were assessed. Each construct incorporated a broad curved LCP with bi-cortical locking screws for distal fixation. In the Cable construct, 2 cables and 2 uni-cortical locking screws were used for proximal fixation. In the LAP construct, the cables were replaced by a LAP with 4 bicortical locking screws. Axial, lateral bending and torsional stiffness were assessed using intact specimen values as a baseline. Axial load to failure was also measured. The LAP construct was significantly stiffer than the cable construct under axial load with a bone gap (simulating a comminuted fracture) (p=0.01). There were no significant differences between the two constructs in any of the other modalities tested. Loading to failure resulted in no significant differences between constructs, in either initial stiffness or peak load. In conclusion the LAP construct enables bi-cortical screw fixation around a prosthesis. Compared to cables, this was stiffer when there was a bone gap and thus should offer improved proximal fixation of Vancouver B1 proximal femoral fractures in cemented THA.
The most concerning infection of allografts and operative procedures
is methicillin resistant An iontophoresis cell was set up with varying concentrations
of Vancomycin within the medulla of a section of sheep tibia, sealed
from an external saline solution. The cell was run for varying times,
Vancomycin concentrations and voltages, to gain information on optimisation
of conditions for impregnating the graft. Each graft was then sectioned
and dust ground from the exposed surface. The dust was serially
washed to extract the Vancomycin and concentrations measured and
plotted for all variables tested.Objectives
Methods
Periprosthetic femur fractures are a serious complication after hip replacement surgery. In an aging population these fractures are becoming more and more common. Open reduction and plate osteosynthesis is one of the available treatment options. To investigate hip stem stability and cement mantle integrity under cyclic loading conditions after plate fixation with screws perforating the cement in the proximal fragment.Introduction
Objective
The aim of this study was to determine the biomechanical behavior of two different implants used in the fixation of proximal humerus fractures. The two implants in this study are specifically designed for the fixation of proximal humerus fractures and both utilize the concept of fixed angle locking screws. Bone densitometry was performed prior to fracture production and fixation. A reproducible three-part fracture was created in paired human cadaveric bone and then fixed using the locking screw implants. Stress/strain curves for the bone-implant construct were created for loads applied in cantilever bending and torsion to determine the relative stiffness below the yield point. Following this each construct was tested to failure with a valgus bending load. The locking nail implant provided a significantly stiffer construct in torsion, valgus, extension and flexion at loads below failure threshold. The valgus load to failure was significantly higher for the nail. The mode of failure was different between implants.