Matrix metalloproteinases (MMPs), responsible
for extracellular matrix remodelling and angiogenesis, might play
a major role in the response of the growth plate to detrimental
loads that lead to overuse injuries in young athletes. In order
to test this hypothesis, human growth plate chondrocytes were subjected
to mechanical forces equal to either physiological loads, near detrimental
or detrimental loads for two hours. In addition, these cells were
exposed to physiological loads for up to 24 hours. Changes in the
expression of MMPs -2, -3 and -13 were investigated. We found that expression of MMPs in cultured human growth plate
chondrocytes increases in a linear manner with increased duration
and intensity of loading. We also showed for the first time that
physiological loads have the same effect on growth plate chondrocytes
over a long period of time as detrimental loads applied for a short
period. These findings confirm the involvement of MMPs in overuse injuries
in children. We suggest that training programmes for immature athletes
should be reconsidered in order to avoid detrimental stresses and
over-expression of MMPs in the growth plate, and especially to avoid
physiological loads becoming detrimental. Cite this article:
Posterolateral tibial plateau fractures account for 7 % of all proximal tibial fractures. Their fixation often requires posterolateral buttress plating. Approaches for the posterolateral corner are not extensile beyond the perforation of the anterior tibial artery through the interosseous membrane. This study aims to provide accurate data about the inferior limit of dissection by providing measurements of the anterior tibial artery from the lateral joint line as it pierces the interosseous membrane. Forty unpaired adult lower limbs cadavers were used. The posterolateral approach to the proximal tibia was performed as described by Frosch et al. Perpendicular measurements were made from the posterior limit of the articular surface of the lateral tibial plateau and fibula head to the perforation of the anterior tibial artery through the interosseous membrane.Introduction
Materials and Methods
Application of an external fixator for type B and C pelvic fractures can be life saving. Anteriorly the fixator half pins can be placed in the long and thick corridor of bone in the supra-acetabular region often referred to as the low anterior ex-fix. Pins in this location are favoured as they are more stable biomechanically. The bone tunnel for the low anterior ex-fix can be visualised with an iliac oblique projection intra-operatively. In some cases despite being outside the articular surface it may still be low enough to pass through the capsular attachment of the hip joint on the anterior inferior iliac spine. We aim to provide radiological markers for the most superior fibres of the capsule to help accurate extra-capsular pin placement within the supra-acetabular bone tunnel. Thirteen cadaveric pelves, embalmed with the method of Thiel, were used for this study. An image intensifier was positioned to acquire an iliac oblique outlet view, such that the supra acetabular bone tunnel was visualised. This was achieved by positioning the beam 30 degrees cephalad and 20 degrees medial. Both left and right hemipelves were examined in this way. A standard size metallic disc was included in all images with in the acetabulum to allow for image calibration. The proximal most fibres of the hip joint capsule were marked with a K-wire so that their relation to the bone tunnel could be clearly seen on the images. Once all images were acquired they were calibrated and analysed using ImageJ Software to estimate the height and maximum width of the bone tunnel as seen on the images and the vertical distance of the superior most fibres of the capsule from the dome of the acetabulum.Introduction
Materials and Methods
Injuries to growth plates may initiate the formation of reversible or irreversible bone-bridges, which may lead to partial or full closure of the growth plate resulting in bone length discrepancy, axis deviation or joint deformity. Blood vessels and vascular invasion are essential for the formation of new bone tissue. The aim of our study was to investigate the spatial and temporal expression VEGF and its receptors R1 and R2 as well as the ingrowth of vessels in the formation of bone bridges in a rat physeal injury model. Quantitative Real Time - Polymerase Chain Reaction (qRT-PCR) was performed for Vascular Endothelial Growth Factor (VEGF) and its R1 and R2 receptors. Samples from the proximal epiphysis, physis and metaphysis of the tibial bone were prepared for immunohistochemical analysis to demonstrate the spatial expression of VEGF and its R1 and R2 receptors as well as laminin. Kinetic expression of VEGF and VEGF-R1 mRNA documented a tendency towards an expression increase on day 7. Histological analysis showed a haematoma containing bone fragments on day 1which was replaced by a bony bridge by day 14. This remodelled and consolidated by day 82. These trabeculae were accompanied by vessel formation. Expression of VEGF was observed on the bone fragments and the haematoma from day 1 through to day 82. Although VEGF-R1 was expressed at all time points the expression of VEGF-R2 was noted until the 14th day. Physeal bone bridge formation is a combination of both enchondral and intramembranous ossification. This is in part triggered by the bony debris observed within the lesion in the first few days. By washing this debris out the likelihood of bone bridge formation may be reduced. We recommend this practice when operating on the physis in order to avoid iatrogenic physeal bar formation.
