Introduction. Differing levels of tendon retraction are found in full-thickness rotator cuff tears. The pathophysiology of tendon degeneration and retraction is unclear. Neoangiogenesis in tendon parenchyma indicates degeneration. Hypoxia inducible factor 1(HIF) and vascular endothelial growth factor (VEGF) are important inducers of neoangiogenesis. Rotator cuff tendons rupture leads to fatty muscle infiltration (FI) and muscle atrophy (MA). The aim of this study is to clarify the relationship between HIF and VEGF expression, neoangiogenesis, FI, and MA in tendon retraction found in full-thickness rotator cuff tears. Methods. Rotator cuff tendon samples of 33 patients with full-thickness medium-sized rotator cuff tears were harvested during reconstructive surgery. The samples were dehydrated and paraffin embedded. For immunohistological determination of VEGF and HIF expression, sample slices were strained with VEGF and HIF antibody dilution. Vessel density and vessel size were determined after Masson-Goldner staining of sample slices. The extent of tendon retraction was determined intraoperatively according to Patte's classification. Patients were assigned to 4 categories based upon Patte tendon retraction grade, including one control group. FI and MA were measured on standardized preoperative shoulder MRI. Results. HIF and VEGF expression, FI, and MA were significantly higher in torn cuff samples compared with healthy tissue (p<0.05). HIF and VEGF expression, and vessel density significantly increased with extent of tendon retraction (p<0.04). A correlation between HIF/VEGF expression and FI and MA could be found (p<0.04). There was no significant correlation between HIF/VEGF expression and neovascularity (p>0.05). Conclusion. Tendon retraction in full-thickness medium-sized rotator cuff tears is characterized by neovascularity, increased VEGF/HIF expression, FI, and MA. VEGF expression and neovascularity may be effective monitoring tools to assess tendon degeneration

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

Aims

To determine whether platelet-rich plasma (PRP) injection improves outcomes two years after acute Achilles tendon rupture.

Aims

The purpose of this study was to: review the efficacy of the induced membrane technique (IMT), also known as the Masquelet technique; and investigate the relationship between patient factors and technique variations on the outcomes of the IMT.

Objectives

The biomembrane (induced membrane) formed around polymethylmethacrylate (PMMA) spacers has value in clinical applications for bone defect reconstruction. Few studies have evaluated its cellular, molecular or stem cell features. Our objective was to characterise induced membrane morphology, molecular features and osteogenic stem cell characteristics.