Diagnosis of peri-prosthetic loosening of total hip and knee arthroplasty using 18F-Fluoride PET/CT.

Periprosthetic loosening, either aseptic or induced by periprosthetic joint infection remains a major long term complication and challenge in orthopedics and trauma surgery. Sensitivity of potential loosening of the material and other causes of a painful prosthesis is essential for choosing the respective treatment option and providing the needed resources. 18F-Fluoride is a radiopharmaceutical which shows a high affinity to bone and a rapid blood clearance. The objective of this study was to assess 18F-Fluoride PET/CT´s sensitivity and specificity in diagnosing periprosthetic loosening in total hip and knee arthroplasty. We included 26 patients with 24 hip and 13 knee prostheses in our retrospective study with radiological or clinical suspicion of peri-prosthetic loosening at least one year after implantation. Results of 18F-Fluoride PET/CT imaging were compared with surgical results or clinical follow-up if surgery was not performed. On the basis of our data we found a sensitivity of 95.00 %, a specificity of 87.04 % and an accuracy of 89.19 % for 18F-Fluoride PET/CT. The results of our study show that 18F-Fluoride PET/CT is a useful and promising technique in diagnosing periprosthetic loosening of total hip and knee arthroplasties. Further investigation should focus on different uptake patterns of the isotope in periprosthetic joint infection and therefore distinguishing aseptic from septic loosening and enhancing the diagnostic value of this imaging method.

Soft Tissue Sarcoma - a Current Review of the Diagnostic and Treatment Strategies. / Weichteilsarkome ­ eine Übersicht aktueller evidenzbasierter Behandlungskonzepte.

Soft tissue sarcomas are a heterogeneous group of neoplasias that due to their often clinically silent appearance often remain undetected or experience delayed treatment. Especially soft tissue swelling is often misinterpreted by patients and doctors and trivialized or verified with an incorrect biopsy technique. The hereby evoked complications for the patients are serious and may be reduced by simply following the available guidelines. The treatment of soft tissue sarcomas requires a close interdisciplinary coordination between specialists in tumor orthopedics, oncology, radiology, pathology and radiotherapy. On the basis of a selective literature review, the following article points out the current evidence on the treatment and illustrates a treatment algorithm.

Bone Metastases - Pathophysiology, Diagnostic Testing and Therapy (Part 2). / Knochenmetastasen ­ Pathophysiologie, Diagnostik und Therapie (Teil 2).

The second part of this review deals with the several options for the surgical therapy of bone metastases according to their anatomical site and the patient's individual prognosis. Although metastases to the bone - with few exceptions - are normally given palliative therapy, patients nowadays reach survival times of several months to years, depending on the underlying tumour entity. Scoring systems are suitable to estimate the patient's prognosis and fracture risk. The indication for operation has to be adapted to these parameters. In order to preserve a high quality of life, a limb saving procedure has to be aimed at. The options include the resection of the metastasis with stabilisation, the sole stabilisation of the affected bone, and wide resection with limb reconstruction using a modular tumor endoprosthesis. With today's anaesthesiological peri- and intraoperative care, a vast number of surgical implants and bone augmentations are available. However, what is important is not the practicability of the procedure, but the oncological justification and patient-adapted selection of surgical therapy.

Multiple Myeloma - Current Standards in Surgical Treatment. / Multiples Myelom ­ aktuelle Standards der operativen Therapie.

BACKGROUND: Multiple myeloma is a haematological blood cancer in elderly patients, in which neoplastic cell populations cause osteolytic destruction in the bone skeleton. More than 50% of all patients sustain pathological fractures during the course of their disease. Of all malignant lesions of the spine, multiple myeloma is the most frequent spinal tumour and accounts for approximately 15% of all cases. 8 - 10% of the patients develop neurological deficits. In addition to systemic antineoplastic therapy, surgical treatment is often required in order to reconstruct and stabilise bone defects associated with multiple myeloma, as well as to address tumour-related complications. METHODS: A comprehensive literature search was performed in PubMed using the keywords "multiple myeloma" and "surgery" or "fracture". This served to evaluate the available primary and secondary literature on the current status of the surgical therapy of multiple myeloma. Systematic reviews, meta-analyses and clinical studies and international recommendations for therapy were included - from 1975 until the spring of 2018. DISCUSSION: Stabilising surgery is essential in order to retain and restore function and mobility in bone sections affected by myeloma and for tumour-related osseous defects due to pathological fracture or instability. Absolute and relative indications for surgical treatment are distinguished and are based on the extent and localisation of bone lesions, manifest fractures, accompanying side effects and complications such as neurological deficits and bone pain that is intractable to conservative treatment. The range of options in surgical treatment of myeloma-related bone damage within the upper and lower extremities ranges from hybrid stabilisation procedures combining bone cement and various implants, to conventional and modular tumour prostheses systems. In spinal surgery, minimally invasive procedures such as kyphoplasty or vertebroplasty, as well as selective decompressive operations, dorsal spinal fusion and vertebral replacement are performed in cases of osseous defects and related fractures or instabilities. The surgical treatment and time of operation is determined by the general individual risk profile and prognosis of the patient with multiple myeloma. The surgical approach should have the objective of a final and load stable solution for the patient, which takes into account the frequent long-term course of the disease. Radiotherapy is often recommended after surgery. CONCLUSION: In therapy of multiple myeloma, surgical treatment is often required in order to reduce distress and retain the function and flexibility of myeloma affected bone sections and the mobility and quality of life of the cancer patient. The range of surgical strategies is complex and demanding.

Activity Pattern Analysis Indicates Increased but Balanced Systemic Coagulation Activity in Response to Surgical Trauma.

In the nonbleeding patient, constant low-level activation of coagulation enables a quick procoagulant response upon an injury. Conversely, local activation of coagulation might influence the systemic activity level of coagulation. To characterize this interaction in more detail, activity pattern analysis was performed in patients undergoing elective surgeries. Blood samples were taken before, during, and 24 hours after surgery from 35 patients undergoing elective minor ( n = 18) and major ( n = 17) orthopaedic surgeries. Plasma levels of thrombin and activated protein C (APC) were measured using oligonucleotide-based enzyme capture assays, while those of prothrombin fragment 1.2, thrombin-antithrombin-complexes, and D-dimer were measured using commercially available enzyme-linked immunosorbent assays. In vitro thrombin generation kinetics were recorded using calibrated automated thrombography. Results showed that median plasma levels of up to 20 pM thrombin and of up to 12 pM APC were reached during surgery. D-dimer levels started to increase at the end of surgery and remained increased 24 hours after surgery, while all other parameters returned to baseline. Peak levels showed no significant differences between minor and major surgeries and were not influenced by the activity state at baseline. In vitro thrombin generation kinetics remained unchanged during surgery. In summary, simultaneous monitoring of the procoagulant and anticoagulant pathways of coagulation demonstrates that surgical trauma is associated with increased systemic activities of both pathways. Activity pattern analysis might be helpful to identify patients at an increased risk for thrombosis due to an imbalance between surgery-related thrombin formation and the subsequent anticoagulant response.

[Bone Metastases - Pathophysiology, Diagnostic Testing and Therapy (Part 1)]. / Knochenmetastasen ­ Pathophysiologie, Diagnostik und Therapie (Teil 1).

In Germany and other European countries, cancer is the second most common cause of death after cardiovascular disease. Although 5-year survival rates for several types of cancer have significantly improved over the last 30 years, metastasis to the bone almost always leads to incurable disease. Aside from the rare primary bone tumours, the treatment of bone metastases now accounts for a major part of tumour orthopaedic workload and requires close interdisciplinary coordination between specialists in oncology, radiology and the discipline of the primary tumour entity. Due to improvements in oncological treatment regimes, long survival times can be achieved. Therefore, the management of so-called "SRE" (skeletal-related events) has gained importance, even in palliative situations. On the basis of a selective literature review, the following article points out the underlying pathophysiological processes of bone metastases and outlines different diagnostic approaches and their relevance in the current clinical setting.

[Multiple Myeloma - Current Status in Diagnostic Testing and Therapy]. / Multiples Myelom ­ aktuelle Standards in Diagnostik und Therapie.

Background Multiple myeloma is a haematological blood cancer of the bone marrow and is classified by the World Health Organisation (WHO) as a plasma cell neoplasm. In multiple myeloma, normal plasma cells transform into malignant myeloma cells and produce large quantities of an abnormal immunoglobulin called monoclonal protein or M protein. This ultimately causes multiple myeloma symptoms such as bone damage or kidney problems. The annual worldwide incidence of multiple myeloma is estimated to be 6 - 7/100,000 and accounts for 1% of all cancer. In Germany, there are about 6,000 cases of newly diagnosed multiple myeloma per annum. In the current era of new agents, such as immunomodulatory drugs and proteasome inhibitors and antibodies, enormous progress has been achieved in the therapy of multiple myeloma. In orthopaedics, it is essential to be able to recognise the of alarming symptoms of multiple myeloma in clinical routine and to be aware of basic diagnostic features to confirm this disease. Surgical treatment of myeloma-related bone lesions - such as stabilisation of pathological fractures - is an important domain of tumour orthopaedic surgery. Methods A comprehensive literature search was performed in PubMed using the keywords "multiple myeloma" and "diagnostic" or "therapy". This served to evaluate the available primary and secondary literature on the current status of the diagnostic testing and therapy of multiple myeloma. Systematic reviews, meta-analyses and clinical studies as well as international recommendations in therapy were included until the spring of 2016. Results There are now very sensitive screening methods for the diagnosis of multiple myeloma. Accurate diagnosis is generally based on several factors, including physical evaluation, patient history, symptoms, and diagnostic testing results. The standards for initial diagnostic tests are determined by blood and urine tests as well as a bone marrow biopsy and skeletal imaging, such as X-rays, CT scans and MRI scans. Major and minor criteria are required to confirm the diagnosis of multiple myeloma and help to determine the classification and staging of multiple myeloma, and whether it is smoldering myeloma (asymptomatic), symptomatic myeloma, or a monoclonal gammopathy of undetermined significance (MGUS). Multiple myeloma treatment options have increased significantly over the last 10 years. Standard of basic myeloma treatment consists of high dose chemotherapy in combination with autologous stem cell transplantation. Several factors may determine multiple myeloma treatment, such as age and general health, results of laboratory and cytogenetic (genomic) tests as well as symptoms and disease complications. After evaluation of these factors, an individual and often multimodal treatment plan is created and implemented in interdisciplinary cooperation. Conventional treatment options have to be evaluated for older patients (> 70 - 75 years), who are not eligible for high dose chemotherapy and autologous stem cell transplantation due to their age and/or severe comorbidities. It is essential to include supportive therapy in the integral treatment concept, in order to control pain or retain function or mobility. Supportive drugs such as bisphosphonates but also radiation therapy and orthopaedic surgery may be required in order to manage complications of the disease as well as side effects of treatment. Conclusion Current studies show promising results in the treatment of multiple myeloma, due to new agents such as immunomodulatory drugs, proteasome inhibitors and antibodies, which may improve prognosis and survival rate among myeloma patients in the future. However treatment algorithms have become more complex and expensive.

Two-stage knee arthrodesis with a modular intramedullary nail due to septic failure of revision total knee arthroplasty with extensor mechanism deficiency.

BACKGROUND: Periprosthetic joint infection is a serious complication and reconstruction after failed revision total knee arthroplasty with significant bone loss and compromised soft-tissues can be challenging. Objective of this study was to assess clinical and functional results, implant survival and infection recurrence rates in patients treated with two-stage arthrodesis after failed revision TKA with extensor mechanism deficiencies due to PJI, and to identify the factors that affect outcomes after surgery. METHODS: Thirty seven patients with PJI treated within a two-stage exchange and reimplantation of an arthrodesis nail between 2008 and 2014 were included. Systemic and local risk factors were graded preoperatively according to McPherson et al. All patients were treated according to a structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford Knee Score and the Visual Analogue Scale. RESULTS: Thirty two of 37 patients (86.5%) were graded as free of infection. Five patients (13.5%) had recurrent infection after arthrodesis with the need of revision surgery. Mean leg-length discrepancy was 2.2cm. The mean VAS for pain was three, the mean Oxford Knee Score was 38±9. Total implant survival at a 74month follow-up was 74.3% (95% CI: 45.4 to 91.1%), as determined by Kaplan-Meier survival curves. Local McPherson Score, as well as number of revisions was found to be of significant influence to the survival rate. CONCLUSIONS: Septic failure of revision knee arthroplasty can be effectively treated with two-stage arthrodesis using a modular intramedullary nail, providing a stable and painless limb with satisfactory functional results and acceptable infection eradication rates.

Phosphaturic Mesenchymal Tumors: Clinicopathologic, Immunohistochemical and Molecular Analysis of 22 Cases Expanding their Morphologic and Immunophenotypic Spectrum.

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm of uncertain histogenesis that has been linked to tumor-induced osteomalacia (TIO) since 1959. The neoplastic cells produce increased amount of FGF23 which results in TIO via uncontrolled renal loss of phosphate (phosphaturia), and consequently diminished bone mineralization. To date, ∼300 cases have been reported. Although there is increasing evidence that PMT can be diagnosed by reproducible histopathologic features, firm diagnosis has been often restricted to cases associated with TIO and, hence, diagnosis of "nonphosphaturic variants" remained challenging. Recently, FGFR1/FN1 gene fusions were detected in roughly half of cases. We herein reviewed the clinicopathologic features of 22 PMTs (15 cases not published before), stained them with an extended immunohistochemical marker panel and examined them by fluorescence in situ hybridization for FGFR1 gene fusions. Patients were 12 males and 9 females (one of unknown sex) aged 33 to 83 years (median: 52 y). Lesions affected the soft tissues (n=11), bones (n=6), sinonasal tract (n=4), and unspecified site (n=1). Most lesions originated in the extremities (9 in the lower and 4 in the upper extremities). Acral sites were involved in 10 patients (6 foot/heel, 3 fingers/hands, and 1 in unspecified digit). Phosphaturia and TIO were recorded in 10/11 and 9/14 patients with detailed clinical data, respectively. Limited follow-up (5 mo to 14 y; median: 16 mo) was available for 14 patients. Local recurrence was noted in one patient and metastasis in another patient. Histologically, 11 tumors were purely of conventional mixed connective tissue type, 3 were chondromyxoid fibroma-like, 2 were hemangio-/glomangiopericytoma-like with giant cells, and 1 case each angiomyolipoma-like and reparative giant cell granuloma-like. Four tumors contained admixture of patterns (predominantly cellular with variable conventional component). Immunohistochemistry showed consistent expression of CD56 (11/11; 100%), ERG (19/21; 90%), SATB2 (19/21; 90%), and somatostatin receptor 2A (15/19; 79%), while other markers tested negative: DOG1 (0/17), beta-catenin (0/14), S100 protein (0/14), and STAT6 (0/7). FGFR1 fluorescence in situ hybridization was positive in 8/17 (47%) evaluable cases. These results add to the phenotypic delineation of PMT reporting for the first time consistent expression of SATB2 and excluding any phenotypic overlap with solitary fibrous tumor or sinonasal glomangiopericytoma. The unifying immunophenotype of the neoplastic cells irrespective of the histologic pattern suggests a specific disease entity with diverse morphotypes/variants rather than different neoplasms unified by TIO.

RANK-ligand and osteoprotegerin as biomarkers in the differentiation between periprosthetic joint infection and aseptic prosthesis loosening.

AIM: To assess serum levels of RANK-ligand (RANKL) and osteoprotegerin (OPG) as biomarkers for periprosthetic joint infection (PJI) and compare their accuracy with standard tests. METHODS: One hundred and twenty patients presenting with a painful total knee or hip arthroplasty with indication for surgical revision were included in this prospective clinical trial. Based on standard diagnostics (joint aspirate, microbiological, and histological samples) and Musculoskeletal Infection Society consensus classification, patients were categorized into PJI, aseptic loosening, and control groups. Implant loosening was assessed radiographically and intraoperatively. Preoperative serum samples were collected and analyzed for RANKL, OPG, calcium, phosphate, alkaline phosphatase (AP), and the bone-specific subform of AP (bAP). Statistical analysis was carried out, testing for significant differences between the three groups and between stable and loose implants. RESULTS: All three groups were identical in regards to age, gender, and joint distribution. No statistically significant differences in the serum concentration of RANKL (P = 0.16) and OPG (P = 0.45) were found between aseptic loosening and PJI, with a trend towards lower RANKL concentrations and higher OPG concentrations in the PJI group. The RANKL/OPG ratio was significant for the comparison between PJI and non-PJI (P = 0.005). A ratio > 60 ruled out PJI in all cases (specificity: 100%, 95%CI: 89, 11% to 100.0%) but only 30% of non-PJI patients crossed this threshold. The positive predictive value remained poor at any cut-off. In the differentiation between stable and loose implants, none of the parameters measured (calcium, phosphate, AP, and bAP) showed a significant difference, and only AP and bAP measurements showed a tendency towards higher values in the loosened group (with P = 0.09 for AP and P = 0.19 for bAP). CONCLUSION: Lower RANKL and higher OPG concentrations could be detected in PJI, without statistical significance.

Silver-coated endoprosthetic replacement of the proximal humerus in case of tumour-is there an increased risk of periprosthetic infection by using a trevira tube?

BACKGROUND AND OBJECTIVES: The aim of our study was to evaluate if there is an increased risk of periprosthetic infection (PJI) in patients following replacement of the proximal humerus by using a modular tumour prosthesis in combination with a trevira tube. METHODS: Thirty patients were treated by using a modular tumour endoprosthesis (MUTARS®) following intra-articular resection of the proximal humerus. Fifteen patients received treatment by using a trevira tube. In 15 further cases the use of a trevira tube was not necessary. The mean follow-up time was 26 months (range: 24 months to 84 months). Both, Enneking score and range of motion (ROM), was evaluated. Further radiographs were obtained in two planes. RESULTS: The survival rate one year after surgery was 83 % and 63 % after two years. We recorded a 96 % survival of the limb two years after surgery. We also observed only one case of periprosthetic joint infection (PJI) in the entire follow-up period in one patient who received treatment with a trevira tube. The mean Enneking score was 20 points (range 8 to 26 points). ROM was equal in both study groups. In total 20 % of the treated patients (n = 6) suffered complications. CONCLUSIONS: Replacement of the proximal humerus by using a trevira tube in combination with a modular tumour endoprosthesis is a safe and viable treatment option for both, bone tumours and metastases. There is no statistically significant increased risk of infection by using trevira tube even among immunosuppressed patients. LEVEL OF EVIDENCE: Level 3, retrospective comparative study.

Falling and fall risk in adult patients with severe haemophilia.

The objective of this study was to define fall rates and to identify possible fall risk factors in adult patients with severe haemophilia. PATIENTS, MATERIAL, METHODS: 147 patients with severe haemophilia A and B were evaluated using a standardized test battery consisting of demographic, medical and clinical variables and fall evaluation. RESULTS: 41 (27.9 %) patients reported a fall in the past 12 months, 22 (53.7 %) of them more than once. Young age, subjective gait insecurity and a higher number of artificial joints seem to be risk factors for falling. CONCLUSION: Falls seem to be a common phenomenon in patients with severe haemophilia. Fall risk screening and fall prevention should be implemented into daily practice.

Radiosynoviorthesis in hemophilic arthropathy: pathologic blood pool imaging on pre-therapeutic bone scintigraphy is not a predictor of treatment success.

PURPOSE: Increased articular 99mTc MDP uptake on blood pool imaging (BPI) of patients with rheumatologic conditions is indicative of active inflammatory changes, and has been suggested as a strong predictor of response to radiosynoviorthesis (RSO). In this study, we aimed to assess the value of pretreatment BPI positivity (i.e. scintigraphic-apparent hyperemia) for successful RSO in hemophilic arthropathy. METHODS: Thirty-four male patients with painful hemophilic arthropathy underwent RSO after failure of conservative treatment. Treated joints comprised the knee in eight, elbow in five, and ankle in 21 patients. Pretreatment triple-phase bone scintigraphy showed hyperemic joints (pathologic BPI) in 17 patients, whereas 17 patients had no increased tracer uptake on BPI. Response to RSO was evaluated 6 months post-treatment by measuring changes in intensity of arthralgia according to the visual analog scale (VAS), bleeding frequency, and range of motion. The association between hyperemia (pathologic BPI) and treatment outcome was examined using nonparametric tests for independent samples. RESULTS: Clinically evident pain relief occurred in 26 patients (76.5 %), and the mean VAS decreased from 7.7 ± 1.1 to 4.6 ± 2.7 (p < 0.001). Joint bleeding frequency (hemarthrosis) decreased from 4.5 ± 0.6 to 2.1 ± 0.4 during the first 6 months after RSO (p < 0.001). For both parameters (pain relief and bleeding frequency), patients experienced a similar benefit from RSO regardless of pretreatment BPI: arthralgia (p = 0.312) and frequency of hemarthrosis (p = 0.396). No significant improvement was observed for range of motion, but it was significantly more restricted in hyperemic joints both before (p = 0.036) and after treatment (p = 0.022). CONCLUSIONS: Hemophilic arthropathy can be effectively treated with RSO regardless of pre-therapeutic BPI. Patients in whom articular hyperemia is not detectable by scintigraphy may have similar (outstanding) outcomes, and thus should not be excluded from treatment.

Thirteen year follow-up of a cementless femoral stem and a threaded acetabular cup in patients younger than fifty years of age.

PURPOSE: Compared to older patients undergoing total hip arthroplasty (THA) younger patients are considered to be more active, thereby exposing the implant to significantly higher loads over a much longer period of time. Additionally, cases of secondary osteoarthritis caused by hip dysplasia, femoral head necrosis or rheumatic diseases are much more frequent than among the average patient population. Therefore, durable implant fixation and low wear rates are extremely important to achieve good long-term implant survival in this group of patients. OBJECTIVE: The aim of this retrospective study was to evaluate the mid- to long-term survival of a cementless femoral stem (Zweymüller® SL stem) and a threaded cup (Bicon SL®) in patients younger than 50 years of age. METHODS: Therefore, a consecutive series of 100 patients (111 hips) aged 50 years or younger (range: 30 to 50 years) was analysed at a mean follow up of 13.5 years. Follow-up assessment included physical examination and radiographic workup. Hip disability osteoarthritis and outcome score (HOOS) and Harris hip score (HHS) were used to evaluate the pre- and post-operative functional outcome, respectively. Patient satisfaction with the surgical result was assessed by standardized questionnaires. RESULTS: The overall survival rate with any revision as endpoint was 96.8 % (95 % CI: 90.5 % to 98.9 %) at ten years. Gender, operation time and the occurence of osteolyses had no influence on joint function or patient satisfaction. We recorded an overall failure rate of 7.4 % (six cases). In four cases (5 %) the prosthesis had to be revised due to aseptic loosening of the cup after 12 years, eight years, 12 years and 11 years, in one case (1.2 %) recurrent luxation led to a revision operation (acetabular cup and head) after three years of primary implantation. In one case an implant failure was recorded (acetabular cup breakage after eight years of implantation). We recorded the occurence of asymptomatic radiolucent lines of the cup in 21 % and of the stem in 35 % in our series. The HOOS was influenced by the presence or abscence of radiolucent lines of the stem. Patients with radiolucent lines of the stem had a median HOOS score of (74 points) compared to those without radiolucent lines (89 points). Other factors, such as "diagnosis led to operation" and "previous operations" had no influence on the HHS and HOOS. CONCLUSION: Our study demonstrates excellent long-term survival of cementless femoral stem in combination with a threaded cup in young patients undergoing total hip arthroplasty.

Single Molecule Microscopy Reveals an Increased Hyaluronan Diffusion Rate in Synovial Fluid from Knees Affected by Osteoarthritis.

Osteoarthritis is a common and progressive joint disorder. Despite its widespread, in clinical practice only late phases of osteoarthritis that are characterized by severe joint damage are routinely detected. Since osteoarthritis cannot be cured but relatively well managed, an early diagnosis and thereby early onset of disease management would lower the burden of osteoarthritis. Here we evaluated if biophysical parameters of small synovial fluid samples extracted by single molecule microscopy can be linked to joint damage. In healthy synovial fluid (ICRS-score < 1) hyaluronan showed a slower diffusion (2.2 µm(2)/s, N = 5) than in samples from patients with joint damage (ICRS-score > 2) (4.5 µm(2)/s, N = 16). More strikingly, the diffusion coefficient of hyaluronan in healthy synovial fluid was on average 30% slower than expected by sample viscosity. This effect was diminished or missing in samples from patients with joint damage. Since single molecule microscopy needs only microliters of synovial fluid to extract the viscosity and the specific diffusion coefficient of hyaluronan this method could be of use as diagnostic tool for osteoarthritis.

Polymicrobial infections reduce the cure rate in prosthetic joint infections: outcome analysis with two-stage exchange and follow-up ≥two years.

PURPOSE: Prosthetic joint infections (PJI) are a serious and challenging complication after total joint arthroplasty. According to the literature, most PJI are monomicrobial infections caused by gram-positive cocci. The number of polymicrobial PJI might be underrepresented in the literature and only limited data are available regarding the outcome of polymicrobial PJI. Our hypothesis was that polymicrobial PJI are associated with a reduced cure rate compared with monomicrobial PJI. METHODS: Routine clinical data were collected and analysed retrospectively as anonymised, aggregated data. A total of 77 consecutive patients with 77 confirmed PJI and proven infectious organism of the hip and knee joint treated within a two-stage exchange concept and a follow-up ≥ two years were investigated. Detection of the infectious organism was based on multiple microbiological cultures taken intra-operatively. Superficial wound swabs or swabs from sinus tracts were not taken into account. Data were grouped into polymicrobial and monomicrobial PJI. The main outcome variable was "definitively free of infection after two years" as published. Second, we considered several variables as potential confounders or as risk factors. RESULTS: A total of 42 men and 35 women with 46 infected total hip arthroplasties and 31 infected total knee arthroplasties were evaluated. In 37 (46.6 %) of our 77 patients a polymicrobial PJI could be detected. We found a significant association between polymicrobial PJI and the outcome parameter definitively free of infection after two years with an odds ratio (OR) of 0.3 [95 % confidence interval (CI) 0.1-1.0]. The rate of patients graded as definitively free of infection after two years was 67.6 % for polymicrobial infections vs. 87.5 % for monomicrobial infections. The American Society of Anesthesiologists (ASA) score (OR 0.4, 95 % CI 0.2-1.0, p = 0.062) was identified as a borderline significant covariable. CONCLUSIONS: Our data suggest that polymicrobial PJI might be underrepresented in the current literature. Additionally, the presence of multiple infectious organisms is associated with a reduced rate after two years with 67.6 vs 87.5 % for monomicrobial infections. Special attention and extra care should be considered for these patients.

Validation of the Charlson comorbidity index in patients undergoing revision total hip arthroplasty.

PURPOSE: The Charlson comorbidity index (CCI) was developed to quantify the influence of comorbidities on survival. The age-related CCI respects patients' age as an additional risk factor. There are several studies available based on administrative data regarding functional outcome, implant survival, resource use and length of hospital stay in patients undergoing primary total hip arthroplasty (THA). To date, there is a lack of knowledge regarding the correlation of the CCI and the age-related CCI in case of revision total hip arthroplasty (RTHA). OBJECTIVE: Our objective was to validate the influence of the CCI and age-related CCI in patients undergoing RTHA regarding complication rate, resource use implant survival and mortality rate. METHODS: Between October 2007 and November 2012, 142 consecutive patients undergoing RTHA were included in this retrospective study. Routine clinical data were collected and analysed as anonymized aggregated data. In accordance to CCI and age-related CCI the rate of complications (internal medical and surgical complications), the length of hospital stay and the need for ICU treatment and the mortality rate was evaluated. Kaplan-Meier survivorship was used to determine implant survival. RESULTS: Twenty-one patients (15%) had a low risk CCI, 59 patients (41%) a moderate risk CCI and 62 patients (44%) a high risk CCI. The mean follow-up was 27 months (range 24-70 months). In total, we recorded 57 complications (40%), of which 45 were surgical (79%) and 12 were internal medical complications (21%). Twenty-four patients (17%) had to undergo revision surgery. CCI and age-related CCI had no influence regarding implant survival. We recorded a significant influence of the age-related CCI in regard to the necessity of postoperative intensive care unit stay and the length of total hospital stay. Further we recorded a significant influence of the CCI and the age-related CCI regarding postoperative complications and internal complications, postoperative dislocation and the need for surgical revision. CONCLUSION: In summary, we conclude that the CCI and the age-related CCI are strong predictors regarding complication rate in patients undergoing RTHA. In a short- to mid-term follow-up, no influence on implant survival is detectable.

Acetabular defect reconstruction in revision hip arthroplasty with a modular revision system and biological defect augmentation.

PURPOSE: Revision of failed total hip arthroplasty with severe acetabular bone loss represents a rare but challenging problem. Anatomic reconstruction with biological defect augmentation as solid bone transplants or cancellous bone restores bone stock while providing good component stability. The objective of this study was to present short- to mid-term results of revision total hip arthroplasty with a modular ring system in a consecutive series of patients with severe acetabular bone loss. METHODS: We retrospectively reviewed 39 consecutive patients (39 hips) with severe acetabular bone loss (Paprosky type 3 A and 3 B) reconstructed with revision total hip arthroplasty using the cementless modular ring system MRS-Titan®. The MRS-Titan® consists of independent ring systems that are adapted modularly to the defect situation. Combined with acetabular defect reconstruction by using cancellous bone in impaction grafting technique, the MRS-Titan® system offers a cement-free revision system that enables defect-adapted customization to individual anatomic matters, bridging of the acetabular bone defect and reconstruction of the centre of rotation. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate clinical and radiographic results. RESULTS: At an average follow up of 31 months (range 12-69 months) 33 of 39 (84.6 %) of the implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included six implant failures (15 %). We recorded one aseptic loosening of the MRS prosthesis after 20 months. Five patients (12.8 %) had to undergo revision surgery because of periprosthetic joint infection. Two patients had a dislocation postoperatively. The mean Harris hip score improved from 27 ± 14 points preoperatively to 76 ± 15 points at the time of last follow up. CONCLUSION: By achieving stable implant fixation and providing potential for biological fixation, treatment of severe acetabular bone loss in revision total hip arthroplasty with the modular ring system MRS-Titan provides a durable solution with good clinical and radiographic results and allows us to accomplish major goals of reconstruction.

Management of severe periacetabular bone loss combined with pelvic discontinuity in revision hip arthroplasty.

PURPOSE: Revision of failed total hip arthroplasty with massive acetabular bone loss resulting in pelvic discontinuity represents a rare but challenging problem. The objective of this study was to present short to mid-term results of revision total hip arthroplasty with a custom-made acetabular implant in a consecutive series of patients with pelvic discontinuity. METHODS: We retrospectively reviewed 18 consecutive patients with massive acetabular bone loss (Paprosky Type 3B) resulting in pelvic discontinuity reconstructed with revision total hip arthroplasty using a custom-made acetabular component. The prosthesis was created on the basis of a thin-cut 1-mm computed tomography (CT) scan of the pelvis. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate the clinical and radiographic results. RESULTS: At an average follow up of 30 months (range 17-62 months) 16 of 18 (88.9%) custom-made implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included two periprosthetic joint infections treated with explantation of the implant. Three patients had recurrent dislocations postoperatively. The mean Harris hip score improved from 28 ± 12 points preoperatively to 69 ± 13 points at the time of last follow up. CONCLUSION: Treatment of acetabular bone loss and pelvic discontinuity with a custom-made acetabular component can provide a durable solution with good clinical and radiographic results.

Evidence of MRSE on a gentamicin and vancomycin impregnated polymethyl-methacrylate (PMMA) bone cement spacer after two-stage exchange arthroplasty due to periprosthetic joint infection of the knee.

BACKGROUND: Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2-24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily. CASE PRESENTATION: We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection. CONCLUSION: According to the authors' knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation.This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers.