Do Organism Profile and Resistance Patterns Change between First and Subsequent Two-Stage Revision for Periprosthetic Joint Infection?

Increasing antibiotic resistance has been reported as an issue in the treatment of periprosthetic joint infection (PJI). A repeat two-stage revision for recurrent PJI is at high risk of reinfection. However, it is unclear if the microorganism profile plays a role with potentially more resistant or polymicrobial infections. This is a retrospective, single-center analysis of two-stage revisions performed between 2011 and 2017. We identified 46 patients who underwent a repeat resection arthroplasty for recurrent PJI of the same joint after a previous two-stage revision of the same joint at the same department. All microbiological findings were analyzed focusing on microbiological spectrum and resistance testing as well as the potential impact on reinfection-free survival. The most common organism found at the time of recurrent PJI were coagulase-negative Staphylococci (39%) followed by Gram-negative organisms (28%). The risk of polymicrobial infections, difficult-to-treat resistant organisms, and Gram-negative infections increased significantly. Among staphylococcal infections, there was a high percentage of methicillin-resistant species and resistance to oral antibiotics. Patients with Gram-negative organisms had a reduced infection-free survivorship, while resistant organisms were not associated with decreased survival. Patients who undergo a repeat two-stage revision for recurrent PJI have more polymicrobial and resistant organisms, although the impact on survivorship is unclear.

Predicting Actual Social Skill Expression from Personality and Skill Self-Concepts.

Social skills are of key importance in everyday and work life. However, the way in which they are typically assessed via self-report questionnaires has one potential downside; self-reports assess individuals' global self-concepts, which do not necessarily reflect individuals' actual social behaviors. In this research, we aimed to investigate how self-concepts assessed via questionnaires relate to skill expression assessed via behavioral observations after short interpersonal simulations. For this, we used an alternative behavior-based skill assessment approach designed to capture expressions of predefined social skills. Self- and observer ratings were collected to assess three different social skills: agency (i.e., getting ahead in social situations), communion (i.e., getting along in social situations), and interpersonal resilience (i.e., staying calm in social situations). We explored how these skills were related to self-concepts by differentiating between a classic personality measure (i.e., Big Five Inventory 2; BFI-2) and a novel skill questionnaire (i.e., Behavioral, Emotional, and Social Skills Inventory; BESSI). The results (N = 137) showed that both personality and skill self-concepts predicted self-rated skill expression, with the BESSI showing incremental validity. For both personality and skills self-concepts, the relationships with observer-rated skill expression were significant for agency but not for communion or interpersonal resilience. We discuss these results and highlight the theoretical and practical importance of differentiating between skill self-concepts and actual skill expression.

Evaluation of a novel classification system to predict local recurrence in sarcoma patients undergoing hemipelvectomy with iliosacral resection.

AIMS: Iliosacral sarcoma resections have been shown to have high rates of local recurrence (LR) and poor overall survival. There is also no universal classification for the resection of pelvic sarcomas invading the sacrum. This study proposes a novel classification system and analyzes the survival and risk of recurrence, when using this system. METHODS: This is a retrospective analysis of 151 patients (with median follow-up in survivors of 44 months (interquartile range 12 to 77)) who underwent hemipelvectomy with iliosacral resection at a single centre between 2007 and 2019. The proposed classification differentiates the extent of iliosacral resection and defines types S1 to S6 (S1 resection medial and parallel to the sacroiliac joint, S2 resection through the ipsilateral sacral lateral mass to the neuroforamina, S3 resection through the ipsilateral neuroforamina, S4 resection through ipsilateral the spinal canal, and S5 and S6 contralateral sacral resections). Descriptive statistics and the chi-squared test were used for categorical variables, and the Kaplan-Meier survival analysis were performed. RESULTS: Resections were S1 in 25/151 patients (17%), S2 in 70/151 (46%), S3 in 33/151 (22%), S4 in 77/151 (11%), S5 in 4/151 (3%), and S6 in 2/151 (1%). An internal hemipelvectomy was performed in 113/151 patients (75%), and 38/151 patients (25%) had an external hemipelvectomy. The predominant types of sarcoma were high-grade osteosarcoma in 48/151 patients (32%), chondrosarcoma in 41/151 (27%), Ewing sarcoma in 33/151 (22%), pleomorphic sarcoma in 17/151 (11%), and others in 2/151 (8%). LR was found in 24/151 patients (15%) with S3, S5, with S6 resections showing the highest rate of LR (p = 0.038). Overall, 19/151 patients (16%) had evidence of metastastic disease at the time of surgery and these patients showed poorer survival when compared to patients with no metastasis. CONCLUSION: The proposed classification can help to report and compare different surgical and reconstructive approaches in these difficult cases who are still have a considerable risk of LR. Cite this article: Bone Joint J 2022;104-B(2):290-296.

The Bateman-Type Soft Tissue Reconstruction around Proximal or Total Humeral Megaprostheses in Patients with Primary Malignant Bone Tumors-Functional Outcome and Endoprosthetic Complications.

We aimed to evaluate the functional outcome and endoprosthetic complications following the Bateman-type soft tissue reconstruction around proximal or total humeral replacements in patients undergoing resection of a primary malignant bone tumor. Between September 2001 and December 2018, a total of 102 patients underwent resection of a primary malignant bone tumor and subsequent reconstruction with a modular humeral megaprosthesis in our department. Fifteen (15%) of these patients underwent a Bateman-type soft tissue reconstruction and were included in this retrospective study. The median Musculoskeletal Tumor Society (MSTS) score was 21, the median Toronto Extremity Salvage Score (TESS) was 70, and the median American Shoulder and Elbow Surgeons (ASES) score was 72. Fifty-three percent (8/15) of all patients required a revision surgery after a median time of 6 months. There were 2 soft tissue failures, 3 infections and 3 tumor recurrences. The revision-free implant survivorship amounted to 53% (95% confidence interval (CI) 28-81) after 1 year and 47% (95% CI 22-73) at last follow-up. The Bateman-type reconstruction is a feasible option for soft tissue reconstruction but functional outcome is overall limited and the risk for revision surgery within the first postoperative year is high.

A project report on the switch from in-class to online tuition in the preparatory course for the knowledge examination for foreign physicians - guidelines for the organization of the online summer semester 2020 at the faculty of medicine of the Westfälische Wilhelms-Universität of Münster.

Introduction: In Germany, foreign physicians are a fixed component of the medical profession. According to the German Medical Licensure Act, physicians having completed their qualification in another country are required to pass a knowledge examination which falls within the competence of examination offices or the regional governments. Project outline: The preparatory course consists of 10 modules. On Fridays, individual cases are discussed in small groups and specific examination techniques are trained. On Saturdays, illnesses are simulated by simulated patients. After each encounter, faculty experts, psychologists and peer group members provide the participants with 360° feedback. Due to the COVID-19 pandemic, the course which had been established 2 years beforehand has now been switched to an online class within one week. Friday units were visualized in power-point presentations and tutorial videos were discussed. On Saturdays, the cases were simulated by simulated patients and transmitted via a telemedicine platform. Results: The course could be conducted without interruptions (75 hours of in-class tuition and 75 hours of online tuition). In the oral evaluation the participants criticized telemedicine as a medium for imparting of practical skills. 7/22 (32%) of the participants underwent the knowledge examination and 6/7 (86%) of them passed it (versus 18/19 of the participants of in-class tuition (95%)). Discussion: There was a clear preference for in-class tuition. It was noted that the telemedical setting entailed some restrictions. However, the switch to online classes did not affect the pass rate. Conclusion: The switch from in-class to online units was feasible. The gained insights were taken into account when conceiving the online semester at our faculty and especially the tuition with the support of simulated patients.

Melorheostosis of the Fossa Intercondylaris Femoris - A Case Report and Review of the Literature.

INTRODUCTION: Melorheostosis is a rare benign bone condition characterized by excessive segmental sclerosis of cortical bone being reminiscent of dripping candle wax. It typically affects the long bones and can cause impingement and nerve compression syndromes that may require surgical treatment. CASE REPORT: We report the case of a 49-year-old male patient with a 12-month history of the left-sided knee pain and a concomitant limitation of his left knee flexion to 90 degree. Radiographic and magnetic resonance imaging revealed the typical radiographic appearance of melorheostosis with an extraosseous lesion in the fossa intercondylaris femoris being causative for the limited knee range of motion. Following the resection of the extraosseous part of the lesion through a direct open approach, the patient is pain free with a maximum of 110 degree knee flexion at 12-month follow-up. CONCLUSION: Melorheostosis can present with manifold clinical manifestations that potentially require surgical treatment. Even in patients with a challenging localization of extraosseous lesions, a good to excellent functional outcome is possible.

Complex Bone Tumors of the Trunk-The Role of 3D Printing and Navigation in Tumor Orthopedics: A Case Series and Review of the Literature.

The combination of 3D printing and navigation promises improvements in surgical procedures and outcomes for complex bone tumor resection of the trunk, but its features have rarely been described in the literature. Five patients with trunk tumors were surgically treated in our institution using a combination of 3D printing and navigation. The main process includes segmentation, virtual modeling and build preparation, as well as quality assessment. Tumor resection was performed with navigated instruments. Preoperative planning supported clear margin multiplanar resections with intraoperatively adaptable real-time visualization of navigated instruments. The follow-up ranged from 2-15 months with a good functional result. The present results and the review of the current literature reflect the trend and the diverse applications of 3D printing in the medical field. 3D printing at hospital sites is often not standardized, but regulatory aspects may serve as disincentives. However, 3D printing has an increasing impact on precision medicine, and we are convinced that our process represents a valuable contribution in the context of patient-centered individual care.

Medical education too: sexual harassment within the educational context of medicine - insights of undergraduates.

BACKGROUND: Assessment of the presence and characteristics of sexual harassment in academic medicine is a global issue. Only limited international data are available so far. METHODS: Aim: To assess the extent of sexual harassment and identify the perpetrators in the student population of the medical school of Münster, Germany. A survey was undertaken, using the Medical Women's International Association sexual harassment questionnaire translated into German. The anonymous online questionnaire was sent as a link to all medical undergraduates at Münster Medical School via a mailing list between 1 October and 30 November 2018. Identifying or potentially identifying data were not collected. Data were analysed by descriptive statistical methods such as categorical variables. Baseline characteristics, e.g. answers by male or female medical students, were correlated with their individual sexual harassment experiences and perpetrator groups by means of univariate analysis. RESULTS: A total of 2162 medical students were asked to participate, with 623 (28.8%) completing the survey. Sexual harassment is a significant issue among medical students at Münster Medical School with over half (58.9%) of all undergraduates being exposed to sexually harassing behaviour. In total, 31.8% of all participants reported having experienced unwanted physical sexual contact such as unwanted physical touching, with 87.6% of the victims being female. Overall, 41.3% personally experienced verbal sexual harassment of which 87.4% were female. Furthermore, 8.5% of undergraduates faced forced sexual contact such as oral, anal or vaginal penetration, intercourse and rape, with all victims being female. Perpetrators in these cases were mostly male medical superiors (7.0%) and male patients (18.3%). In general, most perpetrators were patients, followed by medical superiors and educators, and less frequently by colleagues. CONCLUSIONS: Sexual harassment in medical education and the medical workplace is a significant problem in a German medical school. Most students experiencing sexual harassment are females. Female students also experience the more serious forms of sexual harassment more often.

Construct validity of multiple mini interviews - Investigating the role of stations, skills, and raters using Bayesian G-theory.

Background: One popular procedure in the medical student selection process are multiple mini-interviews (MMIs), which are designed to assess social skills (e.g., empathy) by means of brief interview and role-play stations. However, it remains unclear whether MMIs reliably measure desired social skills or rather general performance differences that do not depend on specific social skills. Here, we provide a detailed investigation into the construct validity of MMIs, including the identification and quantification of performance facets (social skill-specific performance, station-specific performance, general performance) and their relations with other selection measures.Methods: We used data from three MMI samples (N = 376 applicants, 144 raters) that included six interview and role-play stations and multiple assessed social skills.Results: Bayesian generalizability analyses show that, the largest amount of reliable MMI variance was accounted for by station-specific and general performance differences between applicants. Furthermore, there were low or no correlations with other selection measures.Discussion: Our findings suggest that MMI ratings are less social skill-specific than originally conceptualized and are due more to general performance differences (across and within-stations). Future research should focus on the development of skill-specific MMI stations and on behavioral analyses on the extents to which performance differences are based on desirable skills versus undesired aspects.

[Implementation and evaluation of a revised curriculum for psychiatry and psychotherapy]. / Einführung und Evaluation eines neuen Kurrikulums Psychiatrie und Psychotherapie.

BACKGROUND: Medical education in the discipline of psychiatry and psychotherapy at the University of Münster was traditionally focused on the transfer of knowledge via lectures. According to the current guidelines, the medical curriculum was modified as from the winter semester 2016/2017 to be more competency-based and the changes were evaluated. OBJECTIVE: Lectures and seminars were reduced to achieve a better linkage between theoretical and practical knowledge. Moreover, learning goals were formulated based on the German National Competence-based Catalogue of Learning Objectives in Medicine (NKLM) and entrustable professional activities (EPAs). MATERIAL AND METHODS: Almost all previous lectures are now replaced by an inverted classroom concept with e­learning. Theoretical knowledge is deepened by immediate multiple choice (MC) examinations and a seminar, which now focusses on specific practical EPAs. At the end of the semester, the students now undergo a practical, formative examination with simulated patients (actors) in addition to the former MC test. For evaluation, a representative sample of a semester cohort which took part in the previous curriculum and a similar cohort which attended the revised curriculum were investigated. Moreover, variables which might have an impact on the results were assessed, e. g. pre-existing psychiatric knowledge and motivation. RESULTS: Students taught by the modified curriculum showed a significantly better practical performance and no reduction of theoretical knowledge. Relevant influencing factors were not identified. CONCLUSION: The results show that a competency-based modification of the curriculum in the discipline of psychiatry and psychotherapy leads to more practical abilities and thus helps future physicians to be more self-determined.

Medical doctors' job specification analysis: A qualitative inquiry.

Purpose: A qualitative inquiry was conducted to investigate the qualification requirements of medical doctors in different professional fields and from different perspectives. The inquiry was part of an empirical workplace analysis. Methods: Seventy-four structured interviews were conducted and analyzed to examine critical incidents and behaviors of medical doctors working in different professional fields (clinical theory, clinical practice, practitioner) and disciplines, and from three different perspectives (medical doctors, non-medical staff, and patients). In addition, the National Competency-based Catalogue of Learning Objectives for Medical Education (Nationaler Kompetenzbasierter Lernzielkatalog Medizin / NKLM) was used. Results: The results revealed eleven relevant competencies, which could be categorized into three superordinate competence clusters: interpersonal, work-related, and self-related. The perspectives of medical doctors and non-medical staff included all eleven competencies. However, the perspective of patients did not include one interpersonal and two self-related competencies. Nearly all of the critical behaviors mentioned are included in the NKLM. However, the NKLM also includes behaviors that were not mentioned in the interviews. Conclusions: The behavior-oriented interviews resulted in a requirement profile that is very similar in structure to other competency models in occupational contexts. Comparisons of the different perspectives predominantly revealed similarities. However, the patient perspective also revealed interesting differences compared to the perspectives of medical doctors and non-medical staff. The behavior-related results of the interviews can be directly used for the development of exercises in selection and personnel development contexts and for potential appraisals specific to different medical disciplines. In future steps, the results of this initial qualitative step are to be replicated and extended using quantitative studies and a representative sample. The main overall objective is the definition of relevant competencies both for the selection and development of medical students and for the design of potential appraisals as part of personnel development programs in different medical disciplines.

Silver-coated megaprostheses: review of the literature.

Periprosthetic infection remains one of the most serious complications following megaendoprostheses. Despite a large number of preventive measures that have been introduced in recent years, it has not been possible to further reduce the rate of periprosthetic infection. With regard to metallic modification of implants, silver in particular has been regarded as highly promising, since silver particles combine a high degree of antimicrobial activity with a low level of human toxicity. This review provides an overview of the history of the use of silver as an antimicrobial agent, its mechanism of action, and its clinical application in the field of megaendoprosthetics. The benefits of silver-coated prostheses could not be confirmed until now. However, a large number of retrospective studies suggest that the rate of periprosthetic infections could be reduced by using silver-coated megaprostheses.

Eradication rates, risk factors, and implant selection in two-stage revision knee arthroplasty: a mid-term follow-up study.

BACKGROUND: Two-stage revision (TSR) knee arthroplasty is an established treatment, but failure to control infection still occurs in 4-50 % of cases. The aim of this study was to assess the infection eradication rate, risk factors for failure, and the clinical outcome after two-stage revision knee arthroplasty. METHODS: This retrospective study included 59 patients who had undergone at least one two-stage revision procedure due to periprosthetic joint infection (PJI). Demographic data, comorbidities, types of implant, and complications were analyzed. Univariate and multivariate logistic regression analysis were used to identify risk factors for failure. RESULTS: The infections were controlled in 55 patients (93.2 %). The follow-up period was 4.1 (±2.7) years. Infection control was achieved after the first TSR in 42 patients (71.2 %) and after the second TSR in 13 (76.5 %). The percentage of arthrodesis procedures in patients with infection control increased from 16.75 % after one TSR to 69.2 % after two TSRs. Multivariate logistic regression analysis identified body mass index (BMI) (odds ratio 1.22; 95 % confidence intervals, 1.07 to 1.40; p = 0.004) and smoking (OR 21.52; 95 % CI, 2.60 to 178.19; p = 0.004) as risk factors for failure. CONCLUSIONS: Two-stage revision protocols can achieve acceptable results even after a second procedure. It is still unclear whether the choice of implant influences failure rates. Risk factors for failure after two-stage revision were identified. Studies with larger sample sizes are needed in order to support these findings and identify further risk factors. To reduce failure rates, programs should be established to treat or minimize risk factors in patients with PJI.

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.

Improvement of the shoulder function after large segment resection of the proximal humerus with the use of an inverse tumour prosthesis.

PURPOSE: Active shoulder function after segmental tumour resection of the proximal humerus and endoprosthetic reconstruction is regularly compromised, while the overall arm function allows a satisfying use in daily activities. The main functional problem remains the loss of huge parts of the shoulder girdle musculature and its bony attachment. In revision arthroplasty inverse shoulder implants can improve the active range of motion significantly in comparison to anatomical shaped prostheses. The aim of this study was to investigate if these promising experiences are transferable to reconstructions after tumour resection of the proximal humerus by using a modular inverse tumour prosthesis. METHODS: In this study we observed the functional and oncological results of 18 inverse proximal humerus endoprosthetic replacements (IPHP) with the MUTARS system (Implantcast®) after resection of benign (1x giant cell) and malignant (11x primary bone sarcoma, 5x bone metastasis of carcinoma) bone tumours. Mean age at operation was 42 years. The mean postoperative follow-up was 33 months (range ten to 120). RESULTS: Resection margins were wide in 13 and marginal in five patients. Mean reconstruction length was 15.1 cm (range 6-25 cm). Mean operation time was 191 minutes. The axillary nerve was mostly preserved in 78 % (n = 14). At latest follow-up the patients presented a medium MSTS-score of 24.6/30. The mean active arm abduction in the shoulder joint was 78° and 88° active arm elevation for patients with intact axillary nerve function, but significantly reduced for the four patients with compromised deltoid function. One patient needed a surgical revision due to a deep implant infection. CONCLUSIONS: The IPHP offers a significant improvement of active shoulder function in patients in whom the axillary nerve can be preserved in comparison to anatomically-shaped implants. However, for patients without any deltoid function there is no benefit regarding an improved active range of motion using an IPHP.

The minimal invasive direct anterior approach in combination with large heads in total hip arthroplasty - is dislocation still a major issue? a case control study.

BACKGROUND: There have been increasing numbers of publications in recent years on minimally invasive surgery (MIS) for total hip arthroplasty (THA), reporting results with the use of different head sizes, tribologic and functional outcomes. This study presents the results and early complication rates after THA using the direct anterior approach (DAA) in combination with head sizes ≥ 36 mm. METHODS: A total of 113 patients with THA were included in the study. The Harris Hip Score (HHS) was determined, a radiographic evaluation was carried out, and complications were recorded. The minimum follow-up period was 2 years (means 35 ± 7 months). RESULTS: The HHS improved from 43.6 (± 12) to 88.2 (± 14; P < 0.01). One early infection occurred, one periprosthetic fracture, and three cases of aseptic stem loosening. No incorrect positioning of the implants was observed, and there were no dislocations. CONCLUSION: THA with the minimally invasive DAA in combination with large heads is associated with good to very good functional results in the majority of cases. The complication rates are not increased. The rate of dislocation mainly as an complication of the first two years can be markedly reduced in particular.

The primary stability of pelvic reconstruction after partial supraacetabular pelvic resection due to malignant tumours of the human pelvis: a biomechanical in vitro study.

BACKGROUND: Up until now, reconstructions after partial supraacetabular pelvic resection have been done with the use of megaprostheses or allo-/autografs, including screws. The literature states complications in up to 100%. Therefore, the university hospital of Muenster has successfully established a reconstruction using poly-axial screws and titanium rods in combination with a Palacos(®) shroud. The aim of this study was to gather data on primary stability of five different types of reconstruction. METHODS: Using a biomechanical model Load (N), displacement (mm) and stiffness (N/mm) were recorded in load cycles from 100N up to 1050N. FINDINGS: The data shows that reconstructions with poly-axial screws, titanium rods and Palacos(®) can bear a load of up to 1050N without structural damages. The same is valid with an additional bone graft and for a full metal prosthesis. Referring to reconstructions with just bone graft or without graft and Palacos(®) the load-bearing capacity is significantly worse. Additionally, structural damages were recorded in those reconstructions from 700N onwards. INTERPRETATION: Due to the biomechanical results and the save and easy handling, reconstructions with poly-axial screws, titanium rods and Palacos(®) (and, if necessary, bone graft) can be recommended achieving high primary stability for pelvic ring reconstruction after partial supraacetabular pelvic resection.

Giant cell tumors of the axial skeleton.

Background. We report on 19 cases of giant cell tumor of bone (GCT) affecting the spine or sacrum and evaluate the outcome of different treatment modalities. Methods. Nineteen patients with GCT of the spine (n = 6) or sacrum (n = 13) have been included in this study. The mean followup was 51.6 months. Ten sacral GCT were treated by intralesional procedures of which 4 also received embolization, and 3 with irradiation only. All spinal GCT were surgically treated. Results. Two (15.4%) patients with sacral and 4 (66.7%) with spinal tumors had a local recurrence, two of the letter developed pulmonary metastases. One local recurrence of the spine was successfully treated by serial arterial embolization, a procedure previously described only for sacral tumors. At last followup, 9 patients had no evidence of disease, 8 had stable disease, 1 had progressive disease, 1 died due to disease. Six patients had neurological deficits. Conclusions. GCT of the axial skeleton have a high local recurrence rate. Neurological deficits are common. En-bloc spondylectomy combined with embolization is the treatment of choice. In case of inoperability, serial arterial embolization seems to be an alternative not only for sacral but also for spinal tumors.

Determination of zoledronic acid in human urine and blood plasma using liquid chromatography/electrospray mass spectrometry.

A new method for the analysis of 1-hydroxy-2-imidazol-1-yl-phosphonoethyl phosphoric acid (zoledronic acid) in urine and blood samples has been developed. It consists of a derivatisation of the bisphosphonate with trimethylsilyl diazomethane under multiple methylester formation. The formed derivative can, in contrast to the non-derivatised analyte, easily be separated by reversed phase liquid chromatography due to its reduced polarity. Detection is performed by electrospray tandem mass spectrometry. For calibration purposes, a deuterated internal standard has been synthesised in a three-step synthesis starting with d(4)-imidazole. For human urine, the limit of detection (LOD) is 1.2x10(-7) mol/L, limit of quantification (LOQ) is 3.75×10(-7) mol/L in the MRM mode. For human blood plasma, a LOD of 1×10(-7) mol/L and a LOQ of 2.5×10(-7) mol/L were determined. The linear dynamic range comprised 3.5 decades starting at the limit of quantification. The method was successfully applied for the analysis of spiked urine and blood plasma samples as well as samples from two osteoporosis patients.

Surgical difficulties encountered with use of modular endoprosthesis for limb preserving salvage of failed allograft reconstruction after malignant tumor resection.

We reviewed outcomes and discussed surgical difficulties encountered in 10 patients who had modular endoprosthesis for limb preserving salvage of failed allograft reconstruction after malignant tumor resection. Mean allograft survival time before failure was 127.4 months (range, 14-264 months). Mean length of follow-up since endoprosthesis revision surgery was 62.8 months (range, 16-132 months). There was one endoprosthesis failure, resulting in a mean endoprosthesis survival time of 56.9 months (range, 16-132). Complications included arterial laceration, nerve injury, periprosthetic crack fracture, aseptic loosening, and infection. Modular endoprosthesis remain a viable option that should be considered in any limb preserving salvage of failed allograft reconstructions. However, altered anatomy, poor/short remnant host bone, periprosthetic fractures, inadequate soft tissue coverage and infection remain important difficulties encountered.