Background

The effect of corticosteroids on tendon properties is poorly understood, and current data are insufficient and conflicting. The objective of this study was to evaluate the effects of corticosteroids injection on intact and injured rotator cuff (RC) through biomechanical and radiographic analyses in a rat model.

Background: To date, conventional freezing and cryopreservation of articular cartilage has had limited success due to the mechanical injury of cells resulting from uncontrolled ice crystal propagation. Frozen then thawed grafts show a total lack of viable articular cartilage cells and weakened matrix. Directional freezing using a precise velocity offers a new approach to the process of freezing, enabling cryopreservation of articular cartilage for long term storage and implantation.

Hypothesis: Cryopreservation of articular cartilage using directional freezing maintains significant chondrocyte viability and extra cellular matrix quality.

Study Design: Controlled Laboratory Study.

Methods: Articular Cartilage, collected from 20 porcine hind legs harvested immediately after slaughter, was transferred to the processing laboratory for cryopreservation and analysis. Cryopreservation was performed using a directional freezing system (MTG 1315). During preparation for freezing cryoprotectants were injected into the matrix using an array of 20 micron needles. Thirty 15mm cylindrical grafts were examined for cell viability and cell density using fluorescent and confocal microscopy and proteoglycan synthesis via ³⁵SO₄ uptake. Biomechanical assessment was performed on a second set of 9 grafts to determine the matrix instantaneous dynamic modulus of elasticity.

Results: Chondrocyte viability (53%±9%), viable cell density (18900 ± 4100 cell/mm³, 68%±5.7% viability) and ³⁵SO₄ uptake (59% compared to fresh control) were achieved. Biomechanical measures were mildly impaired (62%±5.2%) compared to fresh control due to the injection of cryoprotectants. In addition, chondrocyte viability in the cryopreserved allograft was preferentially maintained in the superficial zone. Similar results were obtained in human in-vitro studies.

Conclusion: Cryopreservation using directional freezing enables the preservation of viable cells within the collagen matrix. These cells are embedded in the supporting hyaline cartilage matrix with good mechanical stability. The behavior of cryopreserved cartilage after transplantation as indicated in sheep transplantations favors the generation of new, healthy hyaline cartilage during one year follow-up. The high percentage of viable cartilage cells, the quality of the matrix following freezing and thawing, and the ability to store these grafts in a hospital facility, are encouraging to meet the growing demand of such allografts in human cartilage repair procedures.

Introduction: Recent studies proved that Colchicine inhibits in-vitro proliferation of osteoblasts and osteosarcoma cells, and that Colchicine is non-selective mitosis inhibitor and selective inhibitor of mineralization. Aim: The aim of this study was to evaluate the effects of Colchicine (CO), given on a daily basis on healing process of bones. Materials and Methods: In a double blind prospective study, 3 groups of adult rats were checked. In each rat the left posterior tibia was broken. The study groups were treated with CO, one week before the fracture in one group, and on the fracture day in other group. The control group was not treated with CO at all. After six weeks the broken tibias were x-rayed and the radiographic union was compared between the groups. After the radiographic evaluation the bones were divided randomly to mechanical and histological evaluation. The union in each sample was estimated by 10 grades histopathological grading system. The mechanical tests were done, by checking the resistance to 3-points bending stress. Results: The results demonstrate signiþcant negative inßuence of chronic colchicine treatment on fracture healing. Radiographically, chronic treatment with colchicine reduced the union chance by 29. Clinically and mechanically, chronic treatment with colchicine reduced signiþcantly (p< 0.02) the callus strength. Pathological examination demonstrated mark reduction in the callus quality (p< 0.0001). Conclusions: In this study we proved that chronic treatment with colchicine reduce bone healing, and maybe the treatment policy (þxation methods, casting time, etc..) of skeletal injuries in colchicine treated patients, should be change.