Background Cathodic voltage-controlled electrical stimulation (CVCES) of titanium implants, either alone or combined with a short course of vancomycin, has previously been shown to reduce the bone and implant bacterial burden in a rodent model of methicillin-resistant Staphylococcus aureus (MRSA) implant-associated infection (IAI). Clinically, the goal is to achieve complete eradication of the IAI; therefore, the rationale for the present study was to evaluate the antimicrobial effects of combining CVCES with prolonged antibiotic therapy with the goal of decreasing the colony-forming units (CFUs) to undetectable levels.Questions/purposes (1) In an animal MRSA IAI model, does combining CVCES with prolonged vancomycin therapy decrease bacteria burden on the implant and surrounding bone to undetectable levels? (2) When used with prolonged vancomycin therapy, are two CVCES treatments more effective than one? (3) What are the longer term histologic effects (inflammation and granulation tissue) of CVCES on the surrounding tissue? Methods Twenty adult male Long-Evans rats with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70). One week after infection, the rats were randomly divided into four groups of five: (1) VANCO: only vancomycin treatment (150 mg/ kg, subcutaneous, twice daily for 5 weeks); (2) VANCO + 1STIM: vancomycin treatment (same as the VANCO group) coupled with one CVCES treatment (À1.8 V for 1 hour on postoperative day [POD] 7); (3) VANCO + 2STIM: vancomycin treatment (same as the VANCO group) coupled with two CVCES treatments (À1.8 V for 1 hour on POD 7 and POD 21); or (4) CONT: no treatment. On POD 42, the implant, bone, and peripheral blood were collected for CFU enumeration and histological analysis, where we compared CFU/mL on the implants and bone among the groups. A pathologist, blinded to the experimental conditions, performed a semiquantitative analysis Clinical Orthopaedics and Related Research ®A Publication of The Association of Bone and Joint Surgeons® of inflammation and granulation tissue present in serial sections of the humeral head for animals in each experimental group. Results The VANCO + 1STIM decreased the implant bacterial burden (median = 0, range = 0-10 CFU/mL) when compared with CONT (median = 5.7 9 10 4 , range = 4.0 9 10 3 À8.0 9 10 5 CFU/mL; difference of medians = À5.6 9 10 4 ; p \ 0.001) and VANCO (median = 4.9 9 10 3 , range = 9.0 9 10 2 À2.1 9 10 4 CFU/mL; difference of medians = À4.9 9 10 3 ; p \ 0.001). The VANCO + 1STIM decreased the bone bacterial burden (median = 0, range = 0-0 CFU/mL) when compared with CONT (median = 1.3 9 10 2 , range = 0-9.4 9 10 2 CFU/ mL; difference of medians = À1.3 9 10 2 ; p \ 0.001) but was not different from VANCO (median = 0, range = 0-1.3 9 10 2 CFU/mL; difference of medians = 0; p = 0.210). The VANCO + 2STIM group had implant CFU (median = 0, range = 0-8.0 9 10 1 CFU/mL) and bone CFU (median = 0, range = 0-2.0 9 10 1 CFU/mL) that were not different from the VANCO + 1STIM treatment ...

Magnesium alloys hold great promise for developing orthopedic implants that are biocompatible, biodegradable, and mechanically similar to bone tissue. This study evaluated the in vitro and in vivo antimicrobial properties of magnesium-9%aluminum-1%zinc (AZ91) and commercially pure titanium (cpTi) against Acinetobacter baumannii (Ab307). The in vitro results showed that as compared to cpTi, incubation with AZ91 significantly reduced both the planktonic (cpTi 5 3.45e8, AZ91 5 8.97e7, p < 0.001) colony forming units (CFU) and biofilm-associated (cpTi 5 3.89e8, AZ91 5 1.78e7, p 5 0.01) CFU of Ab307. However, in vivo results showed no significant differences in the CFU enumerated from the cpTi and AZ91 implants following a 1-week implantation in an established rodent model of Ab307 implant associated infection (cpTi 5 5.23e3, AZ91 5 2.46e3, p 5 0.29). It is proposed that the in vitro results were associated with an increased pH in the bacterial culture as a result of the AZ91 corrosion process. The robust in vivo buffering capacity likely diminished this corrosion associated pH antimicrobial effect.

This article describes a traumatic complete anterior knee dislocation of a previously well-functioning total knee arthroplasty. A thorough physical examination with appropriate radiographic imaging study is required for proper evaluation and treatment of this injury, as it is often associated with neurovascular injury and subsequent global instability of the injured knee is likely.

Superior dislocation of the patella is a rare cause of knee locking, with fewer than 20 cases reported in the English literature. The vast majority of traumatic or even atraumatic knee locking cases are due to such varied conditions as meniscal tears, osteochondral lesions, osteoarthritis, and ligamentous tears. A careful examination with proper radiographic imaging must be undertaken to properly evaluate patients who present with a locked knee, as they may have interdigitating patellofemoral osteophytes. An unusual case of a locked knee secondary to interlocking osteophytes between the femoral condyle and the inferior pole of the patella without a history of trauma is presented. The authors show how local sedation and gentle reduction are usually sufficient treatment, and that the vast majority of patients with this injury quickly return to their baseline functional level without the need for general sedation or surgical treatment.