Reverse Geometry shoulder replacement requires fixation of a base plate (called a metaglene) to the glenoid to which a convex glenosphere is attached. Most systems use screws to achieve this fixation. The suprascapular nerve passes close to the glenoid and is known to be at risk of injury when devices and sutures are inserted into the glenoid. We investigate the risk posed to the suprascapular nerve by placement of metaglene fixation screws. Ten cadaveric shoulder specimens were used. A metaglene was inserted and fixed using 4 screws. The suprascapular nerve was dissected and its branches identified. The screw tips and their proximity to the nerve and branches were identified and recorded.Background
Materials and Methods
Although chondrocytes have been used for autologous implantation in defects of articular cartilage, limited availability and donor-site morbidity have led to the search for alternative cell sources. Mesenchymal stem cells from various sources represent one option. The infrapatellar fat-pad is a promising source. Advantages include low morbidity, ease of harvest and ex-vivo evidence of chondrogenesis. Expansion of MSCs from human fat-pad in FGF-2 has been shown to enhance chondrogenesis. To further elucidate this process, we assessed the role of TGF-?3, FGF-2 and oxygen tension on growth kinetics of these cells during expansion. Infrapatellar fatpads were obtained from 4 donors with osteoarthritis. Cells were expanded in various media formulations (STD, FGF, TGF and FGF/TGF) at both 20% and 5% oxygen tensions. Colony forming unit fibroblast assays were performed for each expansion group and assessed with crystal violet staining. Cell aggregates from each group underwent chondrogenic differentiation in 5% and atmospheric oxygen tension. Pellets were analyzed on day 21. 5% Oxygen tension during expansion increased the colony size for both FGF and FGF/TGF groups. Cells expanded in FGF/TGF proliferated more rapidly. Biochemical analysis revealed that cells expanded in FGF-2 had higher glycosaminoglycan synthesis rates, a marker for chondrogenesis. Differentiation at 5% pO2 led to higher levels of sGAG but its effect was generally less potent compared to expansion in FGF-2.Methods
Results
