On the basis of this analysis, simultaneous bilateral total knee arthroplasty is more cost-effective than staged bilateral total knee arthroplasty, with lower costs and better outcomes for the average patient. These data can inform shared medical decision-making when bilateral total knee arthroplasty is indicated.

No abstract

SUMMARYThe matrix metalloproteinase (MMP) family of extracellular proteases performs crucial roles in development and repair of the skeleton owing to their ability to remodel the extracellular matrix (ECM) and release bioactive molecules. Most MMP-null skeletal phenotypes that have been previously described are mild, thus permitting the assessment of their functions during bone repair in the adult. In humans and mice, MMP2 deficiency causes a musculoskeletal phenotype. In this study, we assessed the role of MMP2 during mouse fracture repair and compared it with the roles of MMP9 and MMP13. Mmp2 was expressed at low levels in the normal skeleton and was broadly expressed in the fracture callus. Treatment of wild-type mice with a general MMP inhibitor, GM6001, caused delayed cartilage remodeling and bone formation during fracture repair, which resembles the defect observed in Mmp9–/– mice. Unlike Mmp9- and Mmp13-null mutations, which affect both cartilage and bone in the callus, the Mmp2-null mutation delayed bone remodeling but not cartilage remodeling. This remodeling defect occurred without changes in either osteoclast recruitment or vascular invasion of the fracture callus compared with wild type. However, we did not detect changes in expression of Mmp9, Mmp13 or Mt1-Mmp (Mmp14) in the calluses of Mmp2-null mice compared with wild type by in situ hybridization, but we observed decreased expression of Timp2 in the calluses of Mmp2-, Mmp9- and Mmp13-null mice. In keeping with the skeletal phenotype of Mmp2-null mice, MMP2 plays a role in the remodeling of new bone within the fracture callus and impacts later stages of bone repair compared with MMP9 and MMP13. Taken together, our results indicate that MMPs play unique and distinct roles in regulating skeletal tissue deposition and remodeling during fracture repair.

Level of evidence IV, case series.

A rectangular footplate design is more resistant to subsidence than a circular footplate design in an ex vivo biomechanical model. The new design had higher load to failure even in the presence of a central defect. These findings suggest that rectangular footplates may provide better subsidence resistance when used to reconstruct defects after thoracolumbar corpectomy.

Understanding the limitations of lateral fluoroscopy when using anterior ankle fusion plates may minimize screw penetration into the subtalar joint and diminish development of subtalar arthropathy.

No abstract