Inclination but not anatomical reconstruction is related with higher cobalt levels in MoM hip arthroplasty.

Metal on Metal total hip arthroplasty is associated with elevated serum cobalt levels. In this study we investigate if there is a relation between the inclination and anteversion angle of the cup and the anatomical reconstruction of the hip on the serum cobalt level. Postoperative cobalt serum levels were measured in 250 patients with the M2a-38 cup and Taperloc stem combination. On standardized radiographs inclination and anteversion angle, lower limb length, lateral offset and center of rotation distance were evaluated. A difference of more than 5 millimeter compared to the preoperative situation was considered as a non-anatomical reconstruction. For every 10 degrees increase in inclination the cobalt level increased 14% (p = 0.036). Women with the same cup inclination angle showed 34% higher cobalt levels than men (p = 0.013). No relation was found between the anteversion angle, anatomical reconstruction and the serum cobalt levels. A higher inclination of the cup leads to higher serum cobalt levels, but a non-anatomical reconstruction has no influence on serum cobalt levels.

Human monoclonal antibodies against Staphylococcus aureus surface antigens recognize in vitro and in vivo biofilm.

Implant-associated Staphylococcus aureus infections are difficult to treat because of biofilm formation. Bacteria in a biofilm are often insensitive to antibiotics and host immunity. Monoclonal antibodies (mAbs) could provide an alternative approach to improve the diagnosis and potential treatment of biofilm-related infections. Here, we show that mAbs targeting common surface components of S. aureus can recognize clinically relevant biofilm types. The mAbs were also shown to bind a collection of clinical isolates derived from different biofilm-associated infections (endocarditis, prosthetic joint, catheter). We identify two groups of antibodies: one group that uniquely binds S. aureus in biofilm state and one that recognizes S. aureus in both biofilm and planktonic state. Furthermore, we show that a mAb recognizing wall teichoic acid (clone 4497) specifically localizes to a subcutaneously implanted pre-colonized catheter in mice. In conclusion, we demonstrate the capacity of several human mAbs to detect S. aureus biofilms in vitro and in vivo.