Antimicrobial Activity of the Most Common Antibiotic-Releasing Systems Employed in Current Orthopedic Surgery: in vitro Study.

PURPOSE OF THE STUDY Infections of joint replacements represent one of the most serious problems in contemporary orthopedics. The joint infections treatment is usually multimodal and involves various combinations of drug delivery and surgical procedures. The aim of this study was to evaluate and compare the bacteriostatic and bactericidal properties of the most common antibiotic carriers used in orthopedic surgery: bone cements mixed with antibiotic and porous calcium sulfate mixed with antibiotic. MATERIAL AND METHODS Three commercial bone cements (Palacos®, Palacos® R+G, Vancogenx®) and commercial porous sulfate (Stimulan®) were prepared with a known concentration of vancomycin (a glycopeptide antibiotic). Specifically, for the purpose of our study, the testing specimens were prepared to release 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, and 512 mg of vancomycin into 1 liter of solution. The specimens with increasing amount of antibiotic were placed in a separate tubes containing 5 mL of Mueller-Hinton broth inoculated with a suspension (0.1 m, McFarland 1) of the reference strain CCM 4223 Staphylococcus aureus to evaluate their bacteriostatic properties (broth dilution method). After this initial incubation and evaluation of the broth dilution method, an inoculum from each tube was transferred onto blood agar plates. After another 24-hour incubation under the same conditions, we evaluated the bactericidal properties (agar plate method). As many as 132 of independent experiments were performed (4 specimens × 11 concentrations × 3 repetitions = 132). RESULTS The bacteriostatic properties of all investigated samples were excellent, perhaps with the exception of the first bone cement (Palacos®). The sample Palacos® started to exhibit bacteriostatic properties at concentrations ≥ 8 mg/mL, while all other samples (Palacos R+G®, Vancogenx®, and Stimulan®) were bacteriostatic in the whole concentration range starting from 1 mg/mL. The bacteriocidic properties did not show such clear trends, but correlated quite well with different properties of the investigated samples during mixing - the most homogeneous samples seemed to exhibit the best and the most reproducible results. DISCUSSION The reliable and reproducible comparison of ATB carriers is a difficult task. The situation is complicated by high numbers of local antibiotic carriers on the market, numerous antibiotics used, and differences in clinical trials at different laboratories. Simple in vitro testing of bacteriostatic and bacteriocidic properties represents a simple and efficient approach to the problem. CONCLUSIONS The study confirmed that the two most common commercial systems used in the orthopedic surgery (bone cements and porous calcium sulfate) prevent bacterial growth (bacteriostatic effect), but they may not be 100% efficient in complete elimination of bacteria (bacteriocidic effect). The scattered results in the case of bacteriocidic tests seemed to be connected with the homogeneity of ATB dispersion in the systems and with the lower reproducibility of the employed agar plate method. Key words: local release of antibiotics; bone cements; calcium sulfate; antimicrobial susceptibility.

[Comparison of Explanted UHMWPE Hip Replacement Components of Various Manufacturers after 10 Years in vivo]. / Porovnání explantovaných UHMWPE komponent náhrady kycelního kloubu ruzných výrobcu po 10 letech in vivo.

PURPOSE OF THE STUDY Considered to be one of the most common causes of aseptic loosening of endoprostheses is the THA failure due to the wear of articulating components, UHMWPE in particular. The purpose of this study is to verify, in terms of oxidative damage and other parameters, the differences between the UHMWPE implants made by various manufacturers explanted for aseptic loosening with the same life span in vivo. MATERIAL AND METHODS In the period 2010-2015, a total of 21 THA articulating components (cups) made of Ultrahigh molecular weight polyethylene by seven different manufacturers were explanted. For each manufacturer, three UHMWPE cups with the same life span (10-12 years after the primary implantation) were evaluated. The damage to the examined joint replacements was described in complexity using three different criteria, namely independently by three evaluators - experienced orthopaedic surgeons. The evaluated criteria were the following: degree of osteolysis determined based on the preoperative radiographs, wear rate of the explanted UHMWPE component, and extent of perioperatively detected granuloma. Oxidative damage and other structural characteristics of explanted cups were studied by means of infrared spectroscopy and microhardness testing. The correlation between the clinical orthopaedic assessment and oxidative damage were statistically processed. RESULTS Strong correlations between the oxidative damage and crystallinity, strong correlations between all types of orthopaedic assessments, negligible correlations between trans-vinylene index and all the other quantities, and moderate correlations between the oxidative damage and clinical evaluation were identified. It was confirmed by experimental measurement that the observed high oxidative damage, resulting in increased crystallinity, manifested itself also in micromechanical properties of the material at the respective site of the THA articulating component. DISCUSSION The discussion includes the comparison of correlations of individual quantities as well as potential effects on the differences in values of components made by individual manufacturers. The values are related to the data in literature and generally accepted claims. CONCLUSIONS At the time of failure almost all the components showed severe or even critical oxidative damage that strongly correlated with the overall clinical evaluation of the damage to the implant. This confirmed that the oxidative degradation is one of the main causes of THA failure. Key words: UHMWPE, oxidation index, crystallinity, THA failure, wear.

Prospective analysis of postoperative wound infections using an early exposure method of wound care.

The management of operative wounds in most surgical procedures is important in preventing many complications, most notably, infection. Among most surgical subspecialties, postsurgical dressings vary in type of materials utilized as well as duration left in place. The authors propose that the contemporary method of postoperative wound management (i.e., dressings left in place until sutures are removed) is overly conservative when dealing with the uncomplicated patient population. This study involves 100 patients who underwent forefoot, rearfoot, or ankle procedures in which skin incisions were made on nonweightbearing surfaces and percutaneous pins, external fixators, or casts were not utilized. All wounds were considered clean and patients displayed an uncomplicated medical history. Postoperatively, the patients were treated by an early exposure method (i.e., the wounds were left undressed on the 4th postoperative day and patients were allowed to bathe in their usual manner). Patients returned on postoperative day 10-14 at which time sutures were removed. Wounds were inspected up to 12 weeks following surgery. An infected wound was defined by the presence of cellulitis or lymphangitis or by the secretion of purulence from the incision line. The incidence of wound infection was 1.0%. This study also includes analysis via questionnaire of the postoperative care utilized by 495 randomly selected diplomates of the American Board of Podiatric Surgery as well as the surgery department chairs at the seven podiatric medical colleges.

Intravascular fasciitis in the foot.

Intravascular fasciitis is a rare benign condition characterized by reactive fibroblastic proliferation arising from the superficial or deep fascia and involving arteries and/or veins. Intravascular fasciitis is a distinct variant of a more common condition called nodular or pseudosarcomatous fasciitis, which possesses clinical and histologic features similar but lacks vascular invasion. The fibroblastic violation of the vascular network suggests a malignant component and often leads to an inappropriate diagnosis for this benign condition. A thorough review of the literature revealed less than 25 reported cases of intravascular fasciitis, with this publication being the only case involving the foot or ankle. A case of intravascular fasciitis affecting the plantar aspect of the foot in a pediatric patient is presented and its clinical and histologic features are discussed.

Major arthrodeses in patients with neuropathic arthropathy.

Neuropathic arthropathy is a complex deformity found in a multitude of disease processes. Various forms of conservative and surgical treatment options have been reported throughout the literature; however, a limited number of such treatments address the underlying deformity. This article reviews the indications and surgical criteria necessary to perform successful arthrodesis procedures in patients afflicted with this problem. A case report is presented, using arthrodesis as a salvage procedure for a painful Charcot deformity of the midfoot in a patient with diabetic neuroarthropathy.

Retrospective analysis of operative ankle fractures.

Closed-ankle fractures presenting to the podiatric service between 1978 and 1991 are reviewed. Patients able to return for follow-up were tested through Cybex isokinetic testing, proprioception, and radiographic studies. All patients reviewed had equal or greater strength and endurance on the involved side when compared to the uninvolved side. Proprioceptive deficits were noted in all patients with lateral malleolar involvement regardless of time of follow-up.