Elemental bioimaging of nanosilver-coated prostheses using X-ray fluorescence spectroscopy and laser ablation-inductively coupled plasma-mass spectrometry.

The distribution of different chemical elements from a nanosilver-coated bone implant was visualized, combining the benefits of two complementary methods for elemental bioimaging, the nondestructive micro X-ray fluorescence (µ-XRF), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Challenges caused by the physically inhomogeneous materials including bone and soft tissues were addressed by polymer embedding. With the use of µ-XRF, fast sample mapping was achieved obtaining titanium and vanadium signals from the metal implant as well as phosphorus and calcium signals representing hard bone tissue and sulfur distribution representing soft tissues. Only by the use of LA-ICP-MS, the required high sensitivity and low detection limits for the determination of silver were obtained. Metal distribution within the part of cancellous bone was revealed for silver as well as for the implant constituents titanium, vanadium, and aluminum. Furthermore, the detection of coinciding high local zirconium and aluminum signals at the implant surface indicates remaining blasting abrasive from preoperative surface treatment of the nanosilver-coated device.

Short-stem reconstruction for megaendoprostheses in case of an ultrashort proximal femur.

BACKGROUND: Tumors of the distal femur and diaphysis with proximal metaphyseal extension into the femur present a challenge for limb salvage. The conventional treatment consists of limb salvage with total femur replacement. This case study aims to present preliminary results and experience with short-stem reconstruction, focusing on the mechanical stability of the procedure. METHODS: Sixteen short stems were implanted in 15 patients. The patients' mean age was 33,3 years (range 11-73). In 10 patients, the stem was used for distal femur reconstruction, in one patient for diaphyseal reconstruction, and in four for a stump lengthening procedure. All of the patients had a primary sarcoma in their history. The mean follow-up period was 37 months (range 5-95 months). The clinical and functional follow-up data were analyzed. RESULTS: Ten patients (67%) were still alive at the time of evaluation. Three complications associated with the stem were noted. In one case, there was aseptic loosening after 58 months; in another, aseptic loosening occurred because the diameter of the stem had initially been too small; and in one case, there was breakage of the fixation screw, without any clinical symptoms. The average Musculoskeletal Tumor Society score for all patients was 23 (range 9-28). The mean result for the distal femur replacement was 24 (range 22-28). None of the surviving patients with distal femur replacements needed any crutches or had a Trendelenburg limp. Both living patients who underwent a stump lengthening procedure were able to walk with an exoprosthesis. CONCLUSIONS: The short stem is a good solution that can prevent or delay proximal femur resection in patients with tumors extending into the proximal metaphyseal femur. Additional risks of proximal femur resection, such as dislocation, opening of another oncological compartment, Trendelenburg limp, and chondrolysis can be avoided.

Femoro-tibial kinematics after TKA in fixed- and mobile-bearing knees in the sagittal plane.

PURPOSE: Lack of the anterior cruciate ligament in total knee arthroplasty results in paradoxical movement of the femur as opposed to the tibia under deep flexion. Total knee arthroplasty with mobile-bearing inlays has been developed to provide increased physiological movement of the knee joint and to reduce polyethylene abrasion. The aim of this study was to perform an in vitro analysis of the kinematic movement in the sagittal plane in order to show differences between fixed- and mobile-bearing TKA in comparison with the natural knee joint. METHODS: Seven knee joints of human cadaver material were used in a laboratory experiment. Fixed- and mobile-bearing inlays were tested in sequences under isokinetic extension in so-called kinemator for knee joints, which can simulate muscular traction power by the use of hydraulic cylinders, which crossover the knee joint. As a target parameter, the a.p. translation of the tibio-femoral relative movement was measured in the sagittal plane under ultrasound (Zebris) control. RESULTS: The results show a reduced tibial a.p. translation in relation to the femur in the bearing group compared to the natural joint. In the Z-axis, between 110° and 50° of flexion, linear movement decreases towards caudal movement under extension. Admittedly, the study did not show differences in the movement pattern between "mobile-bearing" and "fixed-bearing" prostheses. CONCLUSION: Results of this study cannot prove functional advantages of mobile-bearing prostheses for the knee joint kinematic after TKA. Both types of prostheses show typical kinematics of an anterior instability, hence they were incapable of performing physiological movement.

Evaluation of a reconstruction reverse shoulder for tumour surgery and tribological comparision with an anatomical shoulder arthroplasty.

PURPOSE: The functional results after reconstruction of the proximal humerus in tumour surgery are poor. Therefore, a reversed proximal humerus replacement was developed in our institution (MUTARS humerus inverse). A low degree of wear on the polyethylene is required because of the patients' youth and demands on shoulder function. A special type of polyethylene with shock-absorbing properties has been developed to minimise polyethylene wear in the MUTARS inverse proximal humerus replacement. We compared the tribological properties of an anatomical shoulder prosthesis (CAPICA) with the new reversed proximal humerus replacement (MUTARS humerus inverse). METHODS: Both prostheses were tested up to 5 × 10(6) cycles. Every millionth cycle the surface was inspected and a gravimetric measurement was performed. A measurement of surface roughness was done before testing and after 5 × 10(6) cycles. RESULTS: In both prostheses after 5 × 10(6) cycles there were no major defects, such as delamination, observed. In the reversed proximal humerus replacement abrasion of 28 mg/10(6) cycles was detected. The mean abrasion of the anatomical prosthesis was 9.28 mg/ 10(6) cycles. CONCLUSION: The glenoid component of the first reversed humerus replacement (MUTARS humerus inverse) has wear properties comparable to those of normal reversed shoulder prostheses. This is important, as this type of prosthesis is used in young patients after resection of bone tumours, with a good functional outcome. It can, therefore, be expected that the revision rate due to wear will be as high as in patients with normal reversed shoulder prostheses.

Distal femur and proximal tibia replacement with megaprosthesis in revision knee arthroplasty: a limb-saving procedure.

PURPOSE: The aim of the present study was to assess whether using megaprostheses in revision knee arthroplasty procedures allows limb salvage with an acceptable outcome and complication rate, in comparison with other limb-saving procedures. METHODS: Between 2000 and 2010, megaprosthesis implantation was required for non-oncologic indications in 20 patients (21 knees) (average age 73 years). Reconstructions involved the distal femur (n = 15), proximal tibia (n = 4), and both femur and tibia (n = 2). The indications, type, and numbers of previous operations and implants, as well as complications associated with megaprosthesis implantation, were reviewed, and the clinical and radiographic outcomes after an average follow-up period of 34 months (range 10-84 months) were evaluated. RESULTS: The indications for megaprosthesis implantation were periprosthetic infection (n = 5), fracture (n = 9), nonunion (n = 5), and aseptic loosening (n = 2). The types of implant placed before the megaprosthetic reconstruction were a cemented rotating-hinge arthroplasty (n = 16) and a primary total knee arthroplasty (n = 5). Six patients had an additional osteosynthesis of the distal femur. An average of 3.8 operations (range 1-7) had been carried out before megaprosthesis implantation. Complications developed in 11 patients. The Knee Society Score improved significantly, from 43 (± 15) to 68 (± 16.8); P < 0.05. CONCLUSIONS: Megaprosthesis implantation in revision knee arthroplasty is an exceptional indication. Despite the high complication rate, the patients can be spared amputation in most cases, and rapid mobilization with full weight-bearing is possible.

Publication rate of abstracts presented at the Annual Congress of the German Society of Orthopaedics and Trauma Surgery.

INTRODUCTION: The quality of abstracts presented at medical conferences reflects the scientific activity in the organisations involved. The aims of this study were to evaluate the publication rate of studies presented at the annual congress of the German Society of Orthopaedics and Trauma Surgery and to investigate predictive factors for publication. The results were to be compared with other international meetings. METHOD: All 1,100 abstracts presented at the Congress of the German Society of Orthopaedics and Trauma Surgery in 2003 were assessed. The publication rate for the corresponding articles in peer-reviewed journals within 5 years was examined using a PubMed search. The consistency of the congress abstracts with the publications was studied. Factors influencing publication rates were investigated, including level of evidence (LoE) and type of study. RESULTS: The publication rate was 36%, with a mean of 15 months between conference and publication (mean impact factor 1.50). No significant differences were observed between publication rates for oral presentations and posters. Experimental studies and those with LoE I and II had higher publication rates (47.1%; 55.2%; 39.8%) than clinical studies and those with LoE III and IV (30.8%; 29.2%; 28.0%). Abstracts of randomised studies and prospective studies showed publication rates of 43.2 and 35.6% and were published more often than abstracts of non-randomised studies and retrospective studies, with publication rates of 35.3 and 27.1%. CONCLUSION: The publication rate was in the lower range of rates available for comparable conferences--e.g., the American Academy of Orthopaedic Surgeons, with rates between 34 and 55%--but lower than those of the Orthopaedic Trauma Association, at 52-67%. However, 64% of the abstracts remained unpublished, calling into question the acceptability of citing conference abstracts in the scientific literature and implementing them in clinical practice.

Clinical outcome and physical activity measured with StepWatch 3™ Activity Monitor after minimally invasive total hip arthroplasty.

BACKGROUND: Subjective data and physical examinations of patients after total hip arthroplasty are used to assess the outcome. But regarding the physical activity, no objective data can be delivered by existing scores. The level of activity can be measured objectively by counting gait cycles. The aim of this study was to measure activity levels of patients before and after total hip arthroplasty (THA). METHODS: Forty-six patients were included in this prospective study. Western Ontario and McMaster Universities Arthritis Index (WOMAC), Harris Hip Score (HHS), and physical activity level based on the number of steps per day were assessed 1 week before surgery, 6 weeks postoperatively, and 3 months postoperatively. To assess the general constitution of the patients, the American Society of Anesthesiologists (ASA) score and BMI were determined. The physical activity level was measured by StepWatch 3™ Activity Monitor (SAM; Orthocare Innovations, Seattle, WA, USA). The number of GCs per day was assessed. Spearman's rank correlation coefficients were used to identify an association between age, body mass index (BMI), and American Society of Anesthesiologists classification with the number of gait cycles and to detect correlation between GCs and HHS and GCs and WOMAC. RESULTS: From preoperatively to 6 weeks postoperatively, the number of gait cycles did not alter significantly. Three months postoperatively, the number of GC/d and GC/h improved significantly. HHS and WOMAC improved significantly from before surgery to 6 weeks and to 3 months follow-up. The number of gait cycles per day did not correlate with the HHS and the WOMAC score at any point of measurement. Age, BMI, and ASA classification did not influence the results. CONCLUSION: By using a StepWatch 3™ Activity Monitor objective data about physical activity before and after THA can be measured reliable. Subjective and objective data in the postoperative period show different results. Physical activity seems to take longer to reach significantly improved values. By counting gait cycles, surgeons do have an additional tool to measure success after THA.

Does BMI influence clinical outcomes after total knee arthroplasty?

INTRODUCTION: Obesity is a common problem in the western European countries. Since the association between obesity and the emergence of gonarthrosis is approved, it is more important to gain reliable information about this patient group. The aim of the present retrospective study is to evaluate clinical outcomes of German obese patients after total knee arthroplasty (TKA). PATIENTS AND METHODS: Between 2001 and 2009 a total of 199 patients with 230 TKA were included in the present study. The collective was divided into four groups in relation to their Body-Mass-Index (BMI); group 1: BMI < 25 kg/m2, n = 24; group 2: BMI 25-30 kg/m2, n = 80, group 3: BMI 30-40 kg/m2, n = 109; group 4: BMI> 40 kg/m2, n = 17. Clinical outcome measurement was scored postoperatively using the knee society score (KSS), hospital for special surgery score (HSS) and the visual analogue scale (VAS). Furthermore complications and subjective patient satisfaction were noted. RESULTS: We did not detect any significant differences in the clinical scores between the BMI-subgroups. However we measured statistically significant worse results in case of infection and instability in all BMI subgroups (p> 0.01). CONCLUSION: While infection and instability may have a negative influence for the clinical outcome, we did not detect any significant correlation between obesity and exiting complications. Obesity has no significant correlation to influence the outcome after TKA implantation negatively.

Evaluation of osseous integration of PVD-silver-coated hip prostheses in a canine model.

Infection associated with biomaterials used for orthopedic prostheses remains a serious complication in orthopedics, especially tumor surgery. Silver-coating of orthopedic (mega)prostheses proved its efficiency in reducing infections but has been limited to surface areas exposed to soft tissues due to concerns of silver inhibiting osseous integration of cementless stems. To close this gap in the bactericidal capacity of silver-coated orthopedic prostheses extension of the silver-coating on surface areas intended for osseous integration seems to be inevitable. Our study reports about a PVD- (physical-vapor-deposition-) silver-coated cementless stem in a canine model for the first time and showed osseous integration of a silver-coated titanium surface in vivo. Radiological, histological, and biomechanical analysis revealed a stable osseous integration of four of nine stems implanted. Silver trace elemental concentrations in serum did not exceed 1.82 parts per billion (ppb) and can be considered as nontoxic. Changes in liver and kidney functions associated with the silver-coating could be excluded by blood chemistry analysis. This was in accordance with very limited metal displacement from coated surfaces observed by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) 12 months after implantation. In conclusion our results represent a step towards complete bactericidal silver-coating of orthopedic prostheses.

Into the Himalayan exile: the phylogeography of the ground beetle Ethira clade supports the Tibetan origin of forest-dwelling Himalayan species groups.

The Himalayan mountain arc is one of the hotspots of biodiversity on earth, and species diversity is expected to be especially high among insects in this region. Little is known about the origin of the Himalayan insect fauna. With respect to the fauna of high altitude cloud forests, it has generally been accepted that Himalayan lineages are derived from ancestors that immigrated from Western Asia and from adjacent mountainous regions of East and Southeast Asia (immigration hypothesis). In this study, we sought to test a Tibetan Origin as an alternative hypothesis for groups with a poor dispersal ability through a phylogeographic analysis of the Ethira clade of the genus Pterostichus. We sequenced COI mtDNA and the 18S and 28S rDNA genes in 168 Pterostichini specimens, including 46 species and subspecies of the Ethira clade. In our analysis, we were able to show that the Ethira clade is monophyletic and, thus, represents a Himalayan endemic clade, supporting endemism of two of the basal lineages to the Central Himalaya and documenting large distributional gaps within the phylogeographic structure of the Ethira clade. Furthermore, the molecular data strongly indicate very limited dispersal abilities of species and subspecies of these primary wingless ground beetles. These results are consistent with the hypothesis of a Tibetan Origin, which explains the evolution, diversity and distribution of the Himalayan ground beetle Ethira clade much more parsimoniously than the original immigration hypothesis.