Periprosthetic joint infection (PJI) is a potentially devastating complication of orthopedic joint replacement surgery. PJI with associated osteomyelitis is particularly problematic and difficult to cure. Whether viable osteocytes, the predominant cell type in mineralized bone tissue, have a role in these infections is not clear, although their involvement might contribute to the difficulty in detecting and clearing PJI. Here, usingStaphylococcus aureus, the most common pathogen in PJI, we demonstrate intracellular infection of human-osteocyte-like cellsin vitroandS. aureusadaptation by forming quasi-dormant small-colony variants (SCVs). Consistent patterns of host gene expression were observed betweenin vitro-infected osteocyte-like cultures, anex vivohuman bone infection model, and bone samples obtained from PJI patients. Finally, we confirmS. aureusinfection of osteocytes in clinical cases of PJI. Our findings are consistent with osteocyte infection being a feature of human PJI and suggest that this cell type may provide a reservoir for silent or persistent infection. We suggest that elucidating the molecular/cellular mechanism(s) of osteocyte-bacterium interactions will contribute to better understanding of PJI and osteomyelitis, improved pathogen detection, and treatment.IMPORTANCEPeriprosthetic joint infections (PJIs) are increasing and are recognized as one of the most common modes of failure of joint replacements. Osteomyelitis arising from PJI is challenging to treat and difficult to cure and increases patient mortality 5-fold.Staphylococcus aureusis the most common pathogen causing PJI. PJI can have subtle symptoms and lie dormant or go undiagnosed for many years, suggesting persistent bacterial infection. Osteocytes, the major bone cell type, reside in bony caves and tunnels, the lacuno-canalicular system. We report here thatS. aureuscan infect and reside in human osteocytes without causing cell death both experimentally and in bone samples from patients with PJI. We demonstrate that osteocytes respond to infection by the differential regulation of a large number of genes.S. aureusadapts during intracellular infection of osteocytes by adopting the quasi-dormant small-colony variant (SCV) lifestyle, which might contribute to persistent or silent infection. Our findings shed new light on the etiology of PJI and osteomyelitis in general.

We describe a posterolateral transfibular neck approach to the proximal tibia. This approach was developed as an alternative to the anterolateral approach to the tibial plateau for the treatment of two fracture subtypes: depressed and split depressed fractures in which the comminution and depression are located in the posterior half of the lateral tibial condyle. These fractures have proved particularly difficult to reduce and adequately internally fix through an anterior or anterolateral approach. The approach described in this article exposes the posterolateral aspect of the tibial plateau between the posterior margin of the iliotibial band and the posterior cruciate ligament. The approach allows lateral buttressing of the lateral tibial plateau and may be combined with a simultaneous posteromedial and/or anteromedial approach to the tibial plateau. Critically, the proximal tibial soft tissue envelope and its blood supply are preserved. To date, we have used this approach either alone or in combination with a posteromedial approach for the successful reduction of tibial plateau fractures in eight patients. No complications related to this approach were documented, including no symptoms related to the common peroneal nerve, and all fractures and fibular neck osteotomies healed uneventfully.

Modularity at the head-neck junction of the femoral component in THA became popular as a design feature with advantages of decreasing implant inventory and allowing adjustment of leg length, offset, and soft tissue balancing through different head options. The introduction of a new modular interface to femoral stems that were previously monoblock, or nonmodular, comes with the potential for corrosion at the taper junction through mechanically assisted crevice corrosion. The incidence of revision hip arthroplasty is on the rise and along with improved wear properties of polyethylene and ceramic, use of larger femoral head sizes is becoming increasingly popular. Taper corrosion appears to be related to all of its geometric parameters, material combinations, and femoral head size. This review article discusses the pathogenesis, risk factors, clinical assessment, and management of taper corrosion at the head-neck junction.