Quantitative proteomics reveals specific metabolic features of acute myeloid leukemia stem cells.

Acute myeloid leukemia is characterized by the accumulation of clonal myeloid blast cells unable to differentiate into mature leukocytes. Chemotherapy induces remission in the majority of patients, but relapse rates are high and lead to poor clinical outcomes. Because this is primarily caused by chemotherapy-resistant leukemic stem cells (LSCs), it is essential to eradicate LSCs to improve patient survival. LSCs have predominantly been studied at the transcript level, thus information about posttranscriptionally regulated genes and associated networks is lacking. Here, we extend our previous report on LSC proteomes to healthy age-matched hematopoietic stem and progenitor cells (HSPCs) and correlate the proteomes to the corresponding transcriptomes. By comparing LSCs to leukemic blasts and healthy HSPCs, we validate candidate LSC markers and highlight novel and potentially targetable proteins that are absent or only lowly expressed in HSPCs. In addition, our data provide strong evidence that LSCs harbor a characteristic energy metabolism, adhesion molecule composition, as well as RNA-processing properties. Furthermore, correlating proteome and transcript data of the same individual samples highlights the strength of proteome analyses, which are particularly potent in detecting alterations in metabolic pathways. In summary, our study provides a comprehensive proteomic and transcriptomic characterization of functionally validated LSCs, blasts, and healthy HSPCs, representing a valuable resource helping to design LSC-directed therapies.

Low complication rate and better results for intramedullary nail - arthrodesis for infected knee joints compared to external fixator-a series of one hundred fifty two patients.

PURPOSE: Arthrodesis of the knee joint is still a salvage procedure after recurrent prosthetic joint infections (PJI) of total knee arthroplasties (TKA) with substantial bone loss and seems to be a good solution to avoid amputation. Until now, intramedullary arthrodesis has increasingly been performed; no study has yet been published to compare these techniques after septic removal of TKA in terms of functional assessment and quality of daily life. METHODS: In a single-centre retrospective setting, clinical and radiographic evaluation of consecutive patients after knee arthrodesis using intramedullary and external fixation for infected knee joints was performed. All patients were evaluated clinically, with x-ray and questionnaire including analysis regarding any complications at latest follow-up of a minimum 12 months postoperatively. RESULTS: We included 152 patients (75 females, 77 males) in this study. The mean age of the patients at surgery was 63.6 years (range 12 to 90 years). The minimum follow-up was 12 months (mean 3.1 years, range 12 to 49 months). Arthrodesis with external fixator (83 patients, 52.2%) showed less blood loss and less peri-operative complications (1.6%) but a high rate of post-operative, pin-track infections (35.5%); loose pins (12.7%); and pin fractures (4.8%), and therefore risk factors for instability and nonunion (30.9%). Revision rate was 22.6% for arthrodesis with external fixator, and the primary union rate was 65.6%. Intramedullary arthrodesis (69 patients, 43.4%) showed a similar re-infection rate to external fixation (16.1% and 15.9%, respectively) but a significantly lower revision rate (5.4%, p < 0.001). Eighty percent of patients with intramedullary arthrodesis showed very good patient-related outcomes regarding pain, function and daily life activities in the questionnaire. CONCLUSION: Despite similar results regarding patient satisfaction and everyday competences in questionnaires, intramedullary arthrodesis of the knee is superior to the external fixator, as it results in fewer complications, lower revision rate, and union rates/loosening.

Modular tumor prostheses: are current stem designs suitable for distal femoral reconstruction? A biomechanical implant stability analysis in Sawbones.

INTRODUCTION: High loosening rates after distal femoral replacement may be due to implant design not adapted to specific anatomic and biomechanical conditions. MATERIALS AND METHODS: A modular tumor system (MUTARS®, Implantcast GmbH) was implanted with either a curved hexagonal or a straight tapered stems in eight Sawbones® in two consecutively generated bone defect (10 cm and 20 cm proximal to knee joint level). Implant-bone-interface micromotions were measured to analyze main fixation areas and to characterize the fixation pattern. RESULTS: Although areas of highest relative micromotions were measured distally in all groups, areas and lengths of main fixation differed with respect to stem design and bone defect size. Regardless of these changes, overall micromotions could only be reduced with extending bone defects in case of tapered stems. CONCLUSIONS: The tapered design may be favorable in larger defects whereas the hexagonal may be advantageous in defects located more distally.

Diagnosis of periprosthetic joint infection using alpha-defensin test or multiplex-PCR: ideal diagnostic test still not found.

PURPOSE: Diagnosing periprosthetic infection remains a challenge. Multiplex-PCR and biomarkers such as alpha-defensin are potentially useful and fast methods for detecting periprosthetic infection. This study compared these new methods with clinical assessment, conventional microbiological methods and histo-pathological examination. METHODS: Twenty-eight consecutive patients with 30 joints and a mean age of 67.7 years (range 39 to 88) with removal of total hip arthroplasty (THA) or total knee replacement (TKR) were included in this study. Patients were classified according to the modified Musculoskeletal Infection Society score (MSIS) for infected joints. Punction fluid and tissue specimens were taken for conventional microbiological examination, alphadefensin test was performed, a synovial membrane specimen was used for multiplex-PCR and histopathological examination was carried out. RESULTS: The alpha-defensin test and multiplex-PCR showed a sensitivity of 76.9 vs. 30.8% and a specificity of 82.4 vs. 100%, respectively. We found a significant difference between the positive and negative results (p = 0.0023). The conventional microbiological methods were not significantly different from the alpha-defensin test (p = 0.244) with a sensitivity of 84.6% and a specificity of 100% but did differ significantly from the multiplex PCR (p = 0.0030). There was a significant difference between modified MSIS classification and multiplex PCR (p = 0.0007). CONCLUSIONS: Neither alpha-defensin test nor multiplex-PCR could detect periprosthetic infection immediately and reliably. Multiplex-PCR was suitable for detecting the non-infected but not the truly infected. Alpha-defensin test was helpful but showed no satisfactory results. Conventional microbiological methods remain the most reliable for periprosthetic infection diagnosis.

What is the upper limit of cement penetration for different femoral hip resurfacing components?

We used a validated femoral resurfacing model to obtain measurements of pressure and temperature and quantify cement distribution as a function of inner geometry and cementing technique of five different femoral hip resurfacing components. The purpose was to investigate if manufacture cementing recommendations are reliable. ASR showed only with the recommended manual cementing technique low cement pressures of 58.0±50.2kPa and low interface temperatures of 33.3±4.1°C. BHR had large cement defects of 10.4±1.1mm. Conserve Plus caused the smallest cement penetration depths of 2.9±0.6mm. Durom was tolerant against changes of the cementing technique but showed the widest spread of temperature data 42.8±7.0°C. ReCap showed the highest risk for incomplete seating with a cement mantle thickness of 4.3±0.9mm. Polymerization heat did not exceed the threshold of 45°C with a cement penetration depth of less than 4.2mm in any circumstances of this study.

Breakage of Tapered Junctions of Modular Stems in Revision Total Hip Arthroplasty-High Incidence in a Consecutive Series of a Single Institution.

BACKGROUND: Modularity in revision THA (RTHA) has become accepted during the last three decades. Nevertheless, specific risks of modularity of current revision devices such as breakage of taper junctions occur during follow-up. Data reporting failure rates are predominantly given by the manufacturers but independent data acquisition is missing so far. QUESTIONS/PURPOSES: 1. What time-related risk of breakage of taper junction between neck and body of an established modular revision device can be expected in a consecutive single institutional series and a mid-term follow-up? 2. Are there specific factors influencing breakage in this cohort? MATERIALS AND METHODS: A retrospective analysis was performed of a consecutive series of 89 cases after femoral revision using a tapered modular revision stem. Mean follow-up period was 7.1 (range: 3.0-13.7) years. Breakage of stem as failure criteria of the implant was investigated with a Kaplan-Meier analysis. RESULTS: Breakage of taper junctions occurred in four patients during follow-up showing a time-depending implant survival of 94.2 (95% CI: 88.6-100%) after 13.7 years. Implant survival of stems with lateralized necks of 87.4 (95% CI: 75.6-100%) after 13.7 years was significantly lower compared to the standard offset variant with 100% after 13.5 years (log rank test p = 0.0283). Chi square test also revealed a significantly higher risk of breakage of lateralized necks compared to standard offset pieces (p = 0.0141). Three of four patients were obese with a mean BMI of 37.9 kg/m2. Grade of obesity (grade 1 or higher) had significant influence on risk of breakage. Survival of the implant was significantly lower in obese patients with at least grade 1 obesity compared to patients with a BMI < 30 kg/m2 (82.9 (95% CI: 64.9-100%) after 11.6 years vs. 98.4 (95% CI: 95.3-100%) after 13.7 years; log-rank p = 0.0327). CONCLUSIONS: Cumulative risk for failure of taper junctions was high in this consecutive single institutional cohort and may further increase during follow-up. As independent data acquisition in registries is missing, failure rate may be higher than reported data of the manufacturers. The use of lateralized offset necks in obese patients of at least grade 1 obesity showed a significantly higher risk of breakage. The use of monobloc revision devices may be an option, but randomized control trials are currently missing to establish standardized treatment protocols considering individual risks for both monobloc and/or modular implants.

Survival and Clinical Outcomes after Unconstrained Total Knee Arthroplasty for Tibial Plateau Fractures-A Retrospective Study with Minimum 4-Year Follow-Up.

This study investigated survival, complications, revisions, and patient-reported outcomes (PROs) for unconstrained total knee arthroplasty (TKA) in posttraumatic osteoarthritis (PTO) caused by intraarticular tibial plateau fractures with minimum four years follow-up. Forty-nine patients (71.4% male; 58.7 years) were included. Kaplan-Meier analysis was performed with failure defined as TKA removal. Patients without failure underwent pre- and postoperative evaluation (range of motion (ROM), Oxford Knee Score (OKS), Knee Society Score (KSS), anatomical femorotibial angle (aFTA), proximal tibial slope (PTS)) and Short Form-12 (SF-12) Physical (PCS) and Mental Component Summary (MCS) assessment at final follow-up. Fifteen (30.6%) patients had a complication, and eight (16.3%) patients underwent prosthesis removal at median 2.5 years. Cumulative survival rate of TKA was 79.6% at 20 years. A total of 32 patients with a mean follow-up of 11.8 years underwent further analyses. ROM (p = 0.028), aFTA (p = 0.044), pPS (p = 0.009), OKS (p < 0.001) and KSS (p < 0.001) improved significantly. SF-12 PCS was 42.3 and MCS was 54.4 at final follow-up. In general, one third of patients suffer a complication, and one in six patients has their prosthesis removed after TKA for PTO due to tibial plateau fractures. In patients who do not fail, TKA significantly improves clinical and radiographic outcomes at long-term follow-up.

The Therapeutic Role of Plastic and Reconstructive Surgery in the Interdisciplinary Treatment of Soft-Tissue Sarcomas in Germany-Cross-Sectional Results of a Prospective Nationwide Observational Study (PROSa).

Although the involvement of plastic surgery has been deemed important in the treatment of sarcoma patients to avoid oncological compromises and ameliorate patient outcomes, it is not ubiquitously available. The accessibility of defect reconstruction and its therapeutic impact on sarcoma care is the subject of this analysis. Cross-sectional data from 1309 sarcoma patients were collected electronically at 39 German study centers from 2017 to 2019. A total of 621 patients with surgical treatment for non-visceral soft-tissue sarcomas were included. The associated factors were analyzed exploratively using multifactorial logistic regression to identify independent predictors of successful defect reconstruction, as well Chi-squared and Cochran-Mantel-Haenszel tests to evaluate subgroups, including limb-salvage rates in extremity cases. A total of 76 patients received reconstructive surgery, including 52 local/pedicled versus 24 free flaps. Sarcomas with positive margins upon first resection (OR = 2.3, 95%CI = 1.2-4.4) that were excised at centers with lower degrees of specialization (OR = 2.2, 95%CI = 1.2-4.2) were independently associated with the need for post-oncological defect coverage. In this context, the inhouse availability of plastic surgery (OR = 3.0, 95%CI = 1.6-5.5) was the strongest independent predictor for successful flap-based reconstruction, which in turn was associated with significantly higher limb-salvage rates (OR = 1.4, 95%CI = 1.0-2.1) in cases of extremity sarcomas (n = 366, 59%). In conclusion, consistent referral to specialized interdisciplinary sarcoma centers significantly ameliorates patient outcomes by achieving higher rates of complete resections and offering unrestricted access to plastic surgery. The latter in particular proved indispensable for limb salvage through flap-based defect reconstruction after sarcoma resection. In fact, although there remains a scarcity of readily available reconstructive surgery services within the current sarcoma treatment system in Germany, plastic and reconstructive flap transfer was associated with significantly increased limb-salvage rates in our cohort.

En-Bloc Resection of Metastases of the Proximal Femur and Reconstruction by Modular Arthroplasty is Not Only Justified in Patients with a Curative Treatment Option-An Observational Study of a Consecutive Series of 45 Patients.

BACKGROUND: There is little conformity regarding the surgical treatment of metastasis of the proximal femur, especially in palliative patients with limited life expectancy. PATIENTS AND METHODS: En-bloc resection of secondary bone malignancies of the proximal femur and reconstruction by modular arthroplasty was performed in a consecutive series of 45 patients. The mean follow-up period was 16.4 months (0.6-74.7). RESULTS: The survival rate of all patients was 6.6% (95% CI: 0-14.9) at 74.7 months. There was no significant difference in patients with a solitary or disseminated disease at index operation (log-rank p = 0.1214). Recurrent dislocation was the most frequent local complication (n = 6) necessitating an open reduction in four cases. The use of a Trevira tube showed a higher risk of dislocation compared to the simple bonding of remaining soft tissue (6 out of 28 vs. 0 out of 17; Fisher test: p = 0.0463). The worst-case survival rate with the removal of the arthroplasty for any cause and/or loss to follow-up was 80.0% (95% CI: 44.9-100) at 74.7 months (n = 1 due to low-grade infection). CONCLUSIONS: En-bloc resection of metastases and reconstruction by modular arthroplasty is reliable even in patients with very limited life expectancy. Local complications due to tumor growth or instability after intralesional surgery could be managed successfully but recurrent dislocation as the most frequent complication has to be taken into account. The simple bonding of remaining soft tissue around the prosthesis without the use of an attachment tube may reduce the dislocation rate and reoperation risk.

High early post-operative complication rate after elective aseptic orthopedic implant removal of upper and lower limb.

The necessity of orthopedic implant removal is under intense discussion and even if it is performed as an elective procedure, the risk of complications is present. Aim of the study was to identify parameters responsible for an increased risk of early post-operative complications after elective aseptic orthopedic implant removal. We reviewed 1,545 cases of aseptic and elective orthopedic implant removal between 2009 and 2011. The patient́s demographic data, time and duration of operation, patient́s comorbidities, and presence of complications in the first 4 weeks after implant removal were evaluated. Patients with signs of infection at the time of the surgical procedure were excluded from this study. 579 women and 966 men who underwent elective aseptic orthopedic implant removal were identified. Mean age at implant removal was 42 years and mean duration of the surgical procedure was 37 min. In this cohort, 70 patients (4.5%) underwent elective aseptic implant removal after 6pm. 52 patients (3.37%) operated on during daytime suffered from complications post-operatively and five patients (0.3%) who were operated on during the night experienced complications. The parameters age, sex, BMI, and surgeon showed no statistically significant differences for the risk of post-operative complications. Patients' comorbidities such as diabetes seem to have influence but were not statistically significant either. Patients with revision surgery since their first operation, nocturnal surgery and longer duration of the procedure showed a statistically significant higher risk for complications, especially in the lower leg. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1035-1039, 2018.

Patellar blood flow during knee arthroplasty surgical exposure: Intraoperative monitoring by laser doppler flowmetry.

Patellofemoral complications following knee arthroplasty are a well-known problem. Patellar ischemia has been suspected to be causative for fracture, anterior knee pain, and patella component failure. The purpose of this study was to assess the influence of knee arthroplasty surgical dissection on patellar blood flow. Patellar blood flow was measured by means of intraosseous laser Doppler flowmetry (LDF) in 10 patients undergoing total knee arthroplasty by a standard medial parapatellar approach. The initial blood flow was 121.6 +/- 114.7 AU. The signal significantly decreased by 71% (p = 0.0051) when the knee was flexed and lost the pulsatile signal pattern in 80%. After arthrotomy, the signal was 100.1 +/- 120.3 AU in extension. The lowest signal was found in flexion and eversion of the patella (mean, 18 +/- 10.7 AU) and all signals lost pulsatility. As compared to the initial values, completion of the soft tissue dissection did not lead to a significant change of the blood flow signal (121.3 +/- 104.8; p = 0.6835). Flexion of the knee joint markedly reduced patellar perfusion. Standard medial parapatellar approach did not significantly change patellar blood flow. This study does not support the theory of postoperative patellar ischemia as a cause of anterior knee pain or patellofemoral problems.

Influence of implant length and bone defect situation on primary stability after distal femoral replacement in vitro.

BACKGROUND: Aseptic loosening is the major reason for failure of distal femoral replacement using current modular megaprostheses. Although the same stems are used for proximal and distal replacement, survival rates in clinical studies with distal reconstruction were lower within the same system compared to proximal reconstruction. We analyzed whether primary stability as presupposition for long-term fixation can be achieved with a current tapered stem design. Additionally, we hypothesized that stem length affects primary stability depending on bone defect situations. METHODS: A modular tumor system (Megasystem-C®, Link GmbH, Hamburg, Germany) with two different tapered stems (100 and 160mm) was implanted in eight Sawbones® in two consecutively created defect situations (10 and 20cm proximal to knee joint level). Primary rotational stability was investigated by measuring relative micromotions between implant and bone to identify the main fixation areas and to characterize the fixation pattern. RESULTS: The fixation differed between the two stem lengths and with respect to both defect situations; however in each case the main fixation area was located at or close to the femoral isthmus. Highest relative micromotions were measured with the 160-mm stem at the distal end within small bone defects and at the proximal end when defects were increased. CONCLUSIONS: The analyzed design seemed to create sufficient primary stability along the main fixation areas of the implant. Based on these results and with respect to oncologic or potential revision situations, we suggest the use of the shorter stem to be more favorable in case of primary implant fixation.

Influence of cerclages on primary stability of tumor megaprostheses subjected to distal femur defects.

BACKROUND: Purpose of this experimental study was to investigate the influence of cerclages on the primary stability of the MUTARS system using distally fractured synthetic femora. METHODS: 4 MUTARS prostheses were implanted in synthetic femora respectively. Groups consisted of 4 intact bones, 4 fractured with cerclages and 4 fractured bones without cerclages. Spatial micromovements were measured with a high-precision rotational setup. FINDINGS: The order from the weakest to the strongest torque transmission of the intact bones was rm1-rm4-rm2-rm3 (p=0.011) and of the fractured bones with cerclages rm4-rm1-rm3-rm2 (p=0.013). The MUTARS stems broke out of the fractured femoral shaft by removing cerclages (p<0.001) and by the influence of bone defect A (p<0.001). Overall micromovements of the intact bones were lower than those of the fractured bones without cerclages (p<0.001) and overall micromovements of the fractured bones with cerclages were lower than those of bones without cerclages (p<0.001). INTERPRETATION: Due to high press-fit at the proximal and distal isthmus region fissural fractures of the femur may occur. This should always be taken into account. It is advisable to secure them and provide a prophylaxis for these fissural fractures by means of cerclages.

Secretion of matrix metalloproteinase 3 by expanded articular chondrocytes as a predictor of ectopic cartilage formation capacity in vivo.

OBJECTIVE: Monolayer expansion of human articular chondrocytes (HACs) is known to result in progressive dedifferentiation of the chondrocytes and loss of their stable cartilage formation capacity in vivo. For an optimal outcome of chondrocyte-based repair strategies, HACs capable of ectopic cartilage formation may be required. This study was undertaken to identify secreted candidate molecules, in supernatants of cultured HACs, that could serve as predictors of the ectopic cartilage formation capacity of cells. METHODS: Standardized medium supernatants (n = 5 knee cartilage samples) of freshly isolated HACs (PD0) and of HACs expanded for 2 or 6 population doublings (PD2 and PD6, respectively) were screened by a multiplexed immunoassay for 15 distinct interleukins, 8 matrix metalloproteinases (MMPs), and 11 miscellaneous soluble factors. Cartilage differentiation markers such as cartilage oligomeric matrix protein and YKL-40 were determined by enzyme-linked immunosorbent assay. HACs from each culture were subcutaneously transplanted into SCID mice, and the capacity of the chondrocytes to form stable cartilage was examined histologically 4 weeks later. RESULTS: Whereas freshly isolated (PD0) HACs generated stable ectopic cartilage that was positive for type II collagen, none of the cell transplants at PD6 formed cartilaginous matrix. Loss of the ectopic cartilage formation capacity between PD0 and PD6 correlated with a drop in the secretion of MMP-3 to <10% of initial levels, whereas changes in the other investigated molecules were not predictive. Chondrocytes with MMP-3 levels of >or=20% of initial levels synthesized cartilaginous matrix, whereas those with low MMP-3 levels (<10% of initial levels) at PD2 failed to regenerate ectopic cartilage. CONCLUSION: Loss of the capacity for stable ectopic cartilage formation in the course of HAC dedifferentiation can be predicted by determining the relative levels of MMP-3, demonstrating that standardized culture supernatants can be used for quality control of chondrocytes dedicated for cell therapeutic approaches.

The use of tapered stems for femoral revision surgery.

From a biomechanical view point, cementless fixation of a tapered stem has some advantages compared with other techniques to treat severe proximal femoral bone loss in reconstructive hip surgery. We reviewed 129 consecutive revision arthroplasties of the femoral component in which the tapered Wagner self-locking revision stem was used. The mean followup of patients without rerevision of the stem was 8.1 years (range, 5.1-14.1 years). Six revision stems required rerevision (malpositioning, one stem; subsidence, one stem; periprosthetic fracture, one stem; deep infection, three stems) between 0.13 and 4.6 years postoperatively. Using removal of the stem for any cause as the end point, the cumulative survival at 14.1 years was 95.2%. The average Merle d'Aubigné score improved from 7.7 points preoperatively to 14.4 points at the latest followup. Because of new bone formation, the most recent radiographs showed clear, good, or excellent restoration of the proximal femur in 88% of patients. Considering possible late complications such as osteolysis of the femur, aseptic loosening, periprosthetic fracture, and late infection, the shortest stem that ensures sufficient mechanical stability should be used. It may be easier to achieve high primary stability in short stems with a tapered design than with other short stem designs.