Microcomputed tomography assessment of glenoid component cementation techniques in total shoulder arthroplasty

Various strategies have been described to improve glenoid component cementation technique in shoulder arthroplasty, such as the “weephole” technique (WH), which is thought to allow for improved cement mantles by suction venting the glenoid vault through the coracoid. The purpose of this study was to compare the cement mantle created using standard syringe pressurization (SP) to WH or a new, modified weephole technique (MWH), not requiring specific instrumentation of the coracoid medullary canal. Fourteen cadaveric scapulae underwent preparation of the glenoid to allow for implantation of glenoid components. Component fixation was achieved using SP, WH, or MWH. The volumes of cement surrounding each individual peg on the component, of the cement mantle between the back of the glenoid, and of the reamed glenoid face were quantified using micro‐CT. Compared to SP, significantly larger cement mantles were observed around all pegs with both the WH (p = 0.023) and MWH (p = 0.007). Similarly, both the WH and MWH techniques demonstrated significantly decreased cement behind the glenoid component (p = 0.003) compared to SP, with no significant difference between the WH and the MWH techniques. Both WH and MWH techniques increase cement mantle volume around individual pegs and decrease the amount of glenoid face cement compared to conventional SP. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:559–564, 2010     

Glenoid loosening after total shoulder arthroplasty: An in vitro CT‐scan study

Glenoid fixation failure has only been grossly characterized. This lack of information hinders attempts to improve fixation because of a lack of methodologies for detecting and monitoring fixation failure. Our goal was twofold: to collect detailed data of glenoid fixation fracture, and to investigate computed tomography (CT)‐scanning as a tool for investigations of fixation failure. Six cadaver scapulas and six bone‐substitute specimens were cyclically loaded and CT‐scanned at clinical settings after 0, 1,000, 5,000, 10,000, 30,000, 50,000 and 70,000 load cycles. The fixation status was evaluated by inspection of the scans. After 70,000 cycles, the specimens were sectioned, and the fixation inspected by microscopy. The results of the microscopy analysis were compared to the CT‐scan analysis. Fracture of the glenoid fixation initiated at the edge of the glenoid rim and propagated towards and around the keel of the implant. The entire process from initiation to complete fracture took place at the polyethylene implant–cement interface, while the cement, the adjacent bone, and the cement–bone interface remained intact. Thus, strengthening the polyethylene–cement interface should improve glenoid fixation. Microscopy results validated the CT methodology, suggesting that the CT technique is reliable. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1589–1595, 2009