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
One patient deceased, one patient developed Alzheimer dementia, leaving 34 patients available for follow-up. They completed the SF-36 questionnaire and the Simple shoulder test. They were clinically reviewed and scored with the Constant-Murley score. All 34 had complete radiographic work-up (x-ray; ultrasound) preoperatively and at final follow up.
Mean operating time was 35 minutes (SD: +/− 12.33). There were no surgical complications. Postoperatively, there was an uneventful recovery in all patients. At final follow-up, two patients were revised to a RSA. One patient was revised after 9 months because of continuous pain and loss of function. The second patient developed a complete osteonecrosis and was revised after one year. The 32 remaining patients had a preoperative Constant-Murley score adjusted for age and gender of 34,8. This improved to an average of 84 at final follow up. The simple shoulder test improved from an average of 1,8 to 8,4. The average decrease of subacromial space was 2,34 mm and the loss of glenohumeral joint space was 0,57. Finally, the preoperative grade of arthrosis was 0,46 compared to a postoperative average of 1,1. At final follow-up, 85% (27/32) were either satisfied or very satisfied with the result. 12,5% (4/32) appreciated the result as only fair. 2,5% (1/32) was dissatisfied, but didn’t consider revision surgery.
