Postoperative full leg radiographs exhibit less residual coronal varus deformity compared to intraoperative measurements in robotic arm-assisted total knee arthroplasty with the MAKO™ system.

PURPOSE: Robotic arm-assisted total knee arthroplasty (raTKA), currently a major trend in knee arthroplasty, aims to improve the accuracy of implant positioning and limb alignment. However, it is unclear whether and to what extent manual radiographic and navigation measurements with the MAKO™ system correlate. Nonetheless, a high agreement would be crucial to reliably achieve the desired limb alignment. METHODS: Thirty-six consecutive patients with osteoarthritis and a slight-to-moderate varus deformity undergoing raTKA were prospectively included in this study. Prior to surgery and at follow-up, a full leg radiograph (FLR) under weight-bearing conditions was performed. In addition, a computed tomography (CT) scan was conducted for preoperative planning. The hip-knee-ankle angle (HKA), mechanical lateral distal femur angle (mLDFA), mechanical medial proximal tibial angle (mMPTA) and joint line convergence angle (JLCA) were measured in the preoperative and follow-up FLR as well as in the CT scout (without weight-bearing) by three independent raters. Furthermore, the HKA was intraoperatively assessed with the MAKO™ system before and after raTKA. RESULTS: Significantly higher HKA values were identified for intraoperative deformity assessment using the MAKO system compared to the preoperative FLR and CT scouts (p = 0.006; p = 0.05). Intraoperative assessment of the HKA with final implants showed a mean residual varus deformity of 3.2° ± 1.9°, whereas a significantly lower residual varus deformity of 1.4° ± 1.9° was identified in the postoperative FLR (p < 0.001). The mMPTA was significantly higher in the preoperative FLR than in the CT scouts (p < 0.001). Intraoperatively, the mMPTA was adjusted to a mean of 87.5° ± 0.9° with final implants, while significantly higher values were measured in postoperative FLRs (p < 0.001). Concerning the mLDFA, no significant differences could be identified. CONCLUSION: The clinical importance of this study lies in the finding that there is a difference between residual varus deformity measured intraoperatively with the MAKO™ system and those measured in postoperative FLRs. This has implications for preoperative planning as well as intraoperative fine-tuning of the implant position during raTKA to avoid overcorrection of knees with slight-to-moderate varus osteoarthritis. LEVEL OF EVIDENCE: Level IV.

Prediction of complications and surgery duration in primary TKA with high accuracy using machine learning with arthroplasty-specific data.

PURPOSE: The number of primary total knee arthroplasties (TKA) is expected to rise constantly. For patients and healthcare providers, the early identification of risk factors therefore becomes increasingly fundamental in the context of precision medicine. Others have already investigated the detection of risk factors by conducting literature reviews and applying conventional statistical methods. Since the prediction of events has been moderately accurate, a more comprehensive approach is needed. Machine learning (ML) algorithms have had ample success in many disciplines. However, these methods have not yet had a significant impact in orthopaedic research. The selection of a data source as well as the inclusion of relevant parameters is of utmost importance in this context. In this study, a standardized approach for ML in TKA to predict complications during surgery and an irregular surgery duration using data from two German arthroplasty-specific registries was evaluated. METHODS: The dataset is based on two initiatives of the German Society for Orthopaedics and Orthopaedic Surgery. A problem statement and initial parameters were defined. After screening, cleaning and preparation of these datasets, 864 cases of primary TKA (2016-2019) were gathered. The XGBoost algorithm was chosen and applied with a hyperparameter search, a cross validation and a loss weighting to cope with class imbalance. For final evaluation, several metrics (accuracy, sensitivity, specificity, AUC) were calculated. RESULTS: An accuracy of 92.0%, sensitivity of 34.8%, specificity of 95.8%, and AUC of 78.0% were achieved for predicting complications in primary TKA and 93.4%, 74.0%, 96.3%, and 91.6% for predicting irregular surgery duration, respectively. While traditional statistics (correlation coefficient) could not find any relevant correlation between any two parameters, the feature importance revealed several non-linear outcomes. CONCLUSION: In this study, a feasible ML model to predict outcomes of primary TKA with very promising results was built. Complex correlations between parameters were detected, which could not be recognized by conventional statistical analysis. Arthroplasty-specific data were identified as relevant by the ML model and should be included in future clinical applications. Furthermore, an interdisciplinary interpretation as well as evaluation of the results by a data scientist and an orthopaedic surgeon are of paramount importance. LEVEL OF EVIDENCE: Level IV.

The synovial fluid calprotectin lateral flow test for the diagnosis of chronic prosthetic joint infection in failed primary and revision total hip and knee arthroplasty.

PURPOSE: The diagnostic criteria of prosthetic joint infection (PJI) recommended by the most commonly used diagnostic algorithms can be obscured or distorted by other inflammatory processes or aseptic pathology. Furthermore, the most reliable diagnostic criteria are garnered during revision surgery. A robust, reliable addition to the preoperative diagnostic cascade is warranted. Calprotectin has been shown to be an excellent diagnostic marker for PJI. In this study, we aimed to evaluate a lateral flow test (LFT) in the challenging patient cohort of a national referral centre for revision arthroplasty. METHODS: Beginning in March 2019, we prospectively included patients scheduled for arthroplasty exchange of a total hip (THA) or knee arthroplasty (TKA). Synovial fluid samples were collected intra-operatively. We used the International Consensus Meeting of 2018 (ICM) score as the gold standard. We then compared the pre-operative ICM score with the LFT result to calculate its diagnostic accuracy as a standalone pre-operative marker and in combination with the ICM score as part of an expanded diagnostic workup. RESULTS: A total of 137 patients with a mean age of 67 (± 13) years with 53 THA and 84 TKA were included. Ninety-nine patients (72.8%) were not infected, 34 (25.0) were infected, and four (2.9%) had an inconclusive final score and could not be classified after surgery. The calprotectin LFT had a sensitivity (95% confidence interval) of 0.94 (0.80-0.99) and a specificity of 0.87 (0.79-0.93). The area under the receiver operating characteristic curve (AUC) for the calprotectin LFT was 0.94 (0.89-0.99). In nine cases with an inconclusive pre-operative ICM score, the calprotectin LFT would have led to the correct diagnosis of PJI. CONCLUSIONS: The synovial fluid calprotectin LFT shows excellent diagnostic metrics both as a rule-in and a rule-out test, even in a challenging patient cohort with cases of severe osteolysis, wear disease, numerous preceding surgeries, and poor soft tissue conditions, which can impair the common diagnostic criteria. As it is available pre-operatively, this test might prove to be a very useful addition to the diagnostic algorithm.

Machine learning in knee arthroplasty: specific data are key-a systematic review.

PURPOSE: Artificial intelligence (AI) in healthcare is rapidly growing and offers novel options of data analysis. Machine learning (ML) represents a distinct application of AI, which is capable of generating predictions and has already been tested in different medical specialties with various approaches such as diagnostic applications, cost predictions or identification of risk factors. In orthopaedics, this technology has only recently been introduced and the literature on ML in knee arthroplasty is scarce. In this review, we aim to investigate which predictions are already feasible using ML models in knee arthroplasty to identify prerequisites for the effective use of this novel approach. For this reason, we conducted a systematic review of ML algorithms for outcome prediction in knee arthroplasty. METHODS: A comprehensive search of PubMed, Medline database and the Cochrane Library was conducted to find ML applications for knee arthroplasty. All relevant articles were systematically retrieved and evaluated by an orthopaedic surgeon and a data scientist on the basis of the PRISMA statement. The search strategy yielded 225 articles of which 19 were finally assessed as eligible. A modified Coleman Methodology Score (mCMS) was applied to account for a methodological evaluation. RESULTS: The studies presented in this review demonstrated fair to good results (AUC median 0.76/range 0.57-0.98), while heterogeneous prediction models were analysed: complications (6), costs (4), functional outcome (3), revision (2), postoperative satisfaction (2), surgical technique (1) and biomechanical properties (1) were investigated. The median mCMS was 65 (range 40-80) points. CONCLUSION: The prediction of distinct outcomes with ML models applying specific data is already feasible; however, the prediction of more complex outcomes is still inaccurate. Registry data on knee arthroplasty have not been fully analysed yet so that specific parameters have not been sufficiently evaluated. The inclusion of specific input data as well as the collaboration of orthopaedic surgeons and data scientists are essential prerequisites to fully utilize the capacity of ML in knee arthroplasty. Future studies should investigate prospective data with specific and longitudinally recorded parameters. LEVEL OF EVIDENCE: III.

Arthroscopic lateral retinacular release improves patello-femoral and femoro-tibial kinematics in patients with isolated lateral retinacular tightness.

PURPOSE: Arthroscopic lateral retinacular release (LRR) has long been considered the gold standard for the treatment for anterior knee pain caused by lateral retinacular tightness (LRT). However, one-third of patients experience continuous pain postoperatively, which is thought to be related to persistent maltracking of the patella and altered femoro-tibial kinematics. Therefore, the aim of the present study was to simultaneously assess femoro-tibial and patello-femoral kinematics and identify the influence of arthroscopic LRR. METHODS: Sixteen healthy volunteers and 12 patients with unilateral, isolated LRT were prospectively included. Open MRI scans with and without isometric quadriceps contraction were performed in 0°, 30° and 90° of knee flexion preoperatively and at 12 months after surgery. Patellar shift, tilt angle, patello-femoral contact area and magnitude of femoro-tibial rotation were calculated by digital image processing. RESULTS: Postoperatively, patellar shift was significantly reduced at 90° of knee flexion compared to preoperative values. The postoperative patellar tilt angle was found to be significantly smaller at 30° of knee flexion compared to that preoperatively. Isometric muscle contractions did not considerably influence patellar shift or tilt in either group. The patello-femoral contact area increased after LRR over the full range of motion (ROM), with significant changes at 0° and 90°. Regarding femoro-tibial kinematics, significantly increased femoral internal rotation at 0° was observed in the patient group preoperatively, whereas the magnitude of rotation at 90° of knee flexion was comparable to that of healthy individuals. The pathologically increased femoral internal rotation at 30° without muscular activity could be significantly decreased by LRR. With isometric quadriceps contraction no considerable improvement of femoral internal rotation could be achieved by LRR at 30° of knee flexion. CONCLUSIONS: Patello-femoral and femoro-tibial joint kinematics could be improved, making LRR a viable surgical option in carefully selected patients with isolated LRT. However, pathologically increased femoral internal rotation during early knee flexion remained unaffected by LRR and thus potentially accounts for persistent pain. LEVEL OF EVIDENCE: II.

Modular Augmentation in Varus-Valgus-Constrained Knee Arthroplasty-Do We Need Sleeves to Avoid Femoral Loosening After Excessive Distal Augmentation?

BACKGROUND: In revision total knee arthroplasty, zonal fixation methods with a combination of augments, press-fit stems, and sleeves are popular. We hypothesized that high distal femoral augmentation with diaphyseal press-fit stems leads to an increased rate of early aseptic loosening and that femoral metaphyseal sleeves improve implant survival. Therefore, we retrospectively investigated implant survival in relation to augment heights and sleeves. METHODS: A total of 136 patients with mean clinical follow-up of 50 months (range, 28-85) who underwent modular total knee arthroplasty and revision total knee arthroplasty with semiconstrained implants between January 2012 and July 2018 were retrospectively evaluated. Implant survival with 4, 8, and 12 mm distal femoral augments was compared to no distal augmentation. Subsequently, a subgroup analysis was performed for femoral sleeve implantation. RESULTS: We observed an implant survival rate of 97.0%, 87.5%, and 69.2% for 4, 8, and 12 mm distal femoral augmentation, respectively (P = .73; P = .19; P = .008). The implant survival rate with femoral sleeves was 95.8% for the 8 mm augments and 85.7% for the 12 mm augments (P = .42; P = .96). Without femoral sleeves, the implant survival rate was 78.3% with the 8 mm augments and 50.0% with the 12 mm augments (P = .02; P < .001). CONCLUSION: Higher rates of aseptic femoral loosening were identified for distal femoral augmentation of 8 mm or more without metaphyseal sleeve fixation in semiconstrained implants. Thus, in cases with femoral metaphyseal bone damage requiring high distal femoral augmentation, metaphyseal sleeves should be used to avoid early aseptic femoral loosening.

Synovial calprotectin is a reliable biomarker for periprosthetic joint infections in acute-phase inflammation - a prospective cohort study.

PURPOSE: Diagnosing periprosthetic joint infections (PJI) are challenging and may be hampered by the presence of other causes of local inflammation. Conventional synovial and serum markers are not reliable under these circumstances. Synovial calprotectin has been recently shown as a promising biomarker for PJI in total hip (THA) and total knee arthroplasty (TKA). The aim of this study is to investigate if calprotectin is reliable for PJI diagnosis in cases with accompanying inflammation due to recent surgery, dislocation or implant breakage in primary and revision TKA and THA. METHODS: Thirty-three patients were included in this prospective study between July 2019 and October 2021 (17 patients undergoing surgery < 9 months, 11 dislocations, five implant breakage, respectively). Synovial white blood cell count (WBC), percentage of polymorphonuclear neutrophils (PMC), serum C-reactive protein (CRP) and synovial calprotectin, using a lateral-flow-assay, were analysed. These parameters were tested against a modified European-Bone-and-Joint-Infection-Society (EBJIS) definition with adjusted thresholds to account for the local inflammation. Statistic quality criteria were calculated and compared using a binary classification test. RESULTS: Seventeen patients were classified as confirmed infections according to the modified EBJIS definition (13 THA and 4 TKA). The calprotectin assay yielded a sensitivity of 0.88 (0.64, 0.99), a specificity of 0.81 (0.54, 0.96), a positive predictive value (PPV) of 0.83 (0.59, 0.96) and a negative predictive value (NPV) of 0.87 (0.60, 0.98). CONCLUSIONS: Even in the presence of local inflammation due to other, non-infectious causes, calprotectin is a reliable diagnostic parameter for the detection of a PJI in primary and revision THA and TKA.

COVID-19-related cancellation of elective orthopaedic surgery caused increased pain and psychosocial distress levels.

PURPOSE: Health care systems in most European countries were temporarily restructured to provide as much capacity as possible for the treatment of coronavirus disease 2019 (COVID-19) patients. Subsequently, all elective surgeries had to be cancelled and postponed for months. The aim of the present study was to assess the pretreatment health status before and after COVID-19-related cancellation and the psychosocial distress caused by the cancellation. METHODS: For this study, a questionnaire was developed collecting sociodemographic data and information on health status before and after the cancellation. To assess psychosocial distress, the validated depression module of the Patient Health Questionnaire (PHQ-9), was implemented. PHQ-9-Scores of 10 and above were considered to indicate moderate or severe depressive symptoms. In total, 119 patients whose elective orthopaedic surgery was postponed due to the COVID-19 pandemic were surveyed once at least 8 weeks after the cancellation. RESULTS: Seventy-seven patients (65%; 34 female, 43 male) completed the questionnaire and were included. The predominant procedures were total knee arthroplasty (TKA), hip arthroscopy and foot and ankle surgery. The mean pain level significantly increased from 5.5 ± 2.2 at the time of the initially scheduled surgery to 6.2 ± 2.5 at the time of the survey (p < 0.0001). The pain level before cancellation of the surgery was significantly higher in female patients (p = 0.029). An increased analgetic consumption was identified in 46% of all patients. A mean PHQ-9 score of 6.1 ± 4.9 was found after cancellation. PHQ-9 scores of 10 or above were found in 14% of patients, and 8% exhibited scores of 15 points or above. Significantly higher PHQ-9 scores were seen in female patients (p = 0.046). No significant differences in PHQ-9 scores were found among age groups, procedures or reasons for cancellation. CONCLUSION: Cancellation of elective orthopaedic surgery resulted in pain levels that were significantly higher than when the surgery was scheduled, leading to increased analgesic use. Additionally, significant psychosocial distress due to the cancellation was identified in some patients, particularly middle-aged women. Despite these results, confidence in the national health care system and in the treating orthopaedic surgeons was not affected. LEVEL OF EVIDENCE: Level III.

[Implant-associated joint infections]. / Implantatassoziierte Gelenkinfektionen.

Due to the increasing number of endoprosthetic joint replacement operations in older patients as well as in patients with severe primary diseases and comorbidities, the number of revision operations is continuously increasing due to infections. The infection of an endoprosthesis represents a complex clinical picture. This article provides a detailed overview of the treatment of periprosthetic infections with a focus on the diagnostic approach and treatment decision-making. A differentiation is made in periprosthetic infections between infections with a mature or immature biofilm on the surface of the implant. Depending on this, different treatment concepts are available. Highly acute infections represent an orthopedic/surgical emergency in artificial as well as in native joints. Low-grade infections play a role particularly in the area of exchange endoprosthetics. The greatest possible success is achieved only by the interplay of a timely diagnosis, sufficient surgical approach and individualized anti-infective treatment.

[Native joint infections]. / Native Gelenkinfektionen.

Joint infections are a great challenge for the treating physicians. Infection of a native joint can result in the rapid destruction of the joint if treatment is inadequate or delayed and is associated with severe life-threatening diseases, such as sepsis. This article presents a detailed overview of the treatment of joint infections of native joints with a focus on the diagnostic approach and treatment decisions. Infections in native joints are caused either endogenously by hematogenic spreading or are caused by exogenous factors. A relevant proportion of joint infections in native joints occur in connection with iatrogenic measures, such as operations, synovial punctures and joint infiltrations. Fundamentally, acute infections represent an orthopedic surgical emergency, which is associated with the necessity for immediate operative measures. The best possible success can only be achieved by an interaction between early diagnosis, an adequate surgical approach and a tailor-made anti-infectious treatment. This is also the case with periprosthetic infections, which will be dealt with in detail in a second article.

Distribution patterns of foot and ankle tumors: a university tumor institute experience.

BACKGROUND: Bone and soft tissue masses of the foot and ankle are not particularly rare but true neoplasia has to be strictly differentiated from pseudotumorous lesions. Diagnosis is often delayed as diagnostic errors are more common than in other regions. Awareness for this localization of musculoskeletal tumors is not very high and neoplasia is often not considered. The purpose of this study is to provide detailed information on the incidence and distribution patterns of foot and ankle tumors of a university tumor institute and propose a simple definition to facilitate comparison of future investigations. METHODS: As part of a retrospective, single-centre study, the data of patients that were treated for foot and ankle tumors between June 1997 and December 2015 in a musculoskeletal tumor centre were analyzed regarding epidemiologic information, entity and localization. Included were all cases with a true tumor of the foot and ankle. Exclusion criteria were incomplete information on the patient or entity (e.g. histopathological diagnosis) and all pseudotumoral lesions. RESULTS: Out of 7487 musculoskeletal tumors, 413 cases (5,52%) of tumors of the foot and ankle in 409 patients were included (215 male and 198 female patients). The average age of the affected patients was 36 ± 18y (min.3y, max.92y). Two hundred sixty-six tumors involved the bone (64%), among them 231 (87%) benign and 35 (13%) malignant. There were 147 soft tissue tumors (36%), 104 (71%) were benign, 43 (29%) malignant. The most common benign osseous tumor lesions included simple bone cysts, enchondroma and osteochondroma. By far the most common malignant bone tumor was chondrosarcoma. Common benign soft tissue tumors included pigmented villo-nodular synovitis, superifcial fibromatosis and schwannoma whereas the most common malignant members were synovial sarcoma and myxofibrosarcoma. Regarding anatomical localization, the hindfoot was affected most often. CONCLUSIONS: Knowledge of incidence and distribution patterns of foot and ankle tumors will help to correctly assess unclear masses and initiate the right steps in further diagnostics and treatment. Unawareness can lead to delayed diagnosis and inadequate treatment with serious consequences for the affected patient.

Synovial aspiration and serological testing in two-stage revision arthroplasty for prosthetic joint infection: evaluation before reconstruction with a mean follow-up of twenty seven months.

INTRODUCTION: The two-stage revision protocol is the gold standard for controlling and treating low-grade prosthetic joint infections of total hip and total knee arthroplasty. The antibiotic pause for diagnostic reasons before reconstruction (stage two) is discussed in relation to the persistence of the infection and the development of resistant bacterial strains. Serological markers and a synovial analysis are commonly used to exclude the persistence of infection. Therefore, we asked (1) is the serological testing of C-reactive protein and leucocytes a valuable tool to predict a persistence of infection? and (2) what is the role of synovial aspiration of Plymethylmethacrylat (PMMA) spacers in hip and knee joints? MATERIALS AND METHODS: One hundred twelve patients who were MSIS criteria-positive for a prosthetic joint infection were studied, including 45 total hip arthroplasties (THA) and 67 total knee artrhoplasties (TKA) patients. All patients were treated with a two-stage-protocol using a mobile PMMA spacer after a 14-day antibiotic-free interval, during which we measured serological markers (C-reactive protein and leucocytes) and performed synovial aspiration (white blood cell count, polymorphonuclear cell percentage, and microbiological culture) in these patients and compared the results with those of their long-term-follow-up (mean follow-up 27 months, range 24-36 months). RESULTS: Of the 112 patients, 89 patients (79.5%; 95% CI 72-86.9) exhibited infection control after a two-stage exchange, and we detected most methicillin-resistant, coagulase-negative Staphylococci (CoNS) in cases of a persistent infection. The mean sensitivity of serum C-reactive protein in the patients was 0.43 (range 0.23-0.64), and the mean specificity was 0.73 (range 0.64-0.82). For serum leucocytes, the mean sensitivity was 0.09 (range 0-0.29), and the mean specificity was 0.81 (range 0.7-0.92). The mean sensitivity for the WBC count in the synovial fluid (PMMA spacer aspiration) was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). For the PMN percentage, the mean sensitivity was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). No cut-off values could be established for C-reactive protein, leucocytes, WBC count and PMN percentage due to the low AUC. CONCLUSION: No reliable markers were identified for the long-term persistence of infection. C-reactive protein and leucocytes were often elevated, even when the infection was controlled. In addition, normalized serum markers did not exclude the persistence of infection during follow-up. The synovial analysis of the WBC count and PMN percentage did not predict the persistence of infection. However, microbiological synovial fluid analysis is often misleading due to false positive microbiological cultures, which results in overtreatment.

Prognostic factors and outcome of Liposarcoma patients: a retrospective evaluation over 15 years.

BACKGROUND: Soft tissue sarcomas are rare entities with over 50 histological subtypes. Liposarcoma (LS) is the most common neoplasm in this group; it is a complex neoplasm that is divided into different histological subtypes. Different therapy options, such as surgical resection, radiation, and chemotherapy, are available. Depending on the subtype, location, status of the resection margins and metastatic status, different therapy options are used. Therefore, the aim of this study was to determine the prognostic factors influencing the survival of patients affected by LS with consideration for the grading, histological subtype, state of the resection margin, size, location, metastases and local recurrence in a retrospective, single-centre analysis over 15 years. METHODS: We included 133 patients (male/female = 67/66) in this study. We recorded the histologic subtype, grade, TNM classification, localization, biopsy technique, tumour margins, number of operations, complications, radiation and dose, chemotherapy, survival, recrudescence, metastases and follow-up. Survivorship analysis was performed. RESULTS: We detected 56 (43%; 95%-CI 34.6-51.6%) atypical LS cases, 21 (16.2%; 95%-CI 9.8-22.5) dedifferentiated LS cases, 40 (30.8%; 95%-CI 22.8-38.7) myxoid LS cases and 12 (9.2%; 95%-CI 4.3-14.2) pleomorphic LS cases. G1 was the most common grade, which was followed by G3. Negative margins (R0) were detected in 67 cases (53.6%; 95%-CI 44.9-62.3) after surgical resection. Local recurrence was detected in 23.6% of cases. The presence of metastases and dedifferentiated LS subtype as well as negative margins, grade and tumour size are significant prognostic factors of the survival rates (p < 0.015). CONCLUSION: Grading, LS subtype, negative margins after surgery, metastases and tumour size are independently associated with disease-specific survival, and patients with local recurrence had lower survival rates. We hope our investigation may facilitate a further prospective study and clinical decision-making in LS.

Distal femoral replacement with the MML system: a single center experience with an average follow-up of 86 months.

BACKGROUND: The aim of this study was to compare the functional outcomes and complication rates after distal femoral replacement (DFR) performed with the modular Munich-Luebeck (MML) modular prosthesis (ESKA/Orthodynamics, Luebeck, Germany) in patients being treated for malignant disease or failed total knee arthroplasty. METHODS: A retrospective review of patient charts and a functional investigation (involving Musculoskeletal Tumor Society Score [MSTS], American Knee Society Score [AKSS], Oxford Knee Score [OKS], Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Toronto Extremity Salvage Score [TESS], the 12-Item Short-Form [SF-12] Health Survey, and a failure classification system developed by Henderson et al.) of DFR cases from 2002 to 2015 were conducted. The indications for DFR were malignant tumor resection in the femur (n = 20, group A) or failure of revision total knee arthroplasty without a history of malignant disease (n = 16, group B). RESULTS: One-hundred and twenty-nine patients were treated during the study period. Of these, 82 were analyzed for complications and implant-survival. Further, 36 patients were available for functional assessment after a mean follow-up of 86 months (range: 24-154). There were 75 complications in total. The overall failure rate for DFR was 64.6% (53/82 patients). The most common failure mechanisms were type III (mechanical failure), followed by type I (soft tissue) and type II (aseptic loosening). The mean MSTS score (out of 30) was 17 for group A and 12 for group B. All the clinical outcome scores revealed an age-dependent deterioration of function. CONCLUSION: DFR is an established procedure to restore distal femoral integrity. However, complication rates are high. Post-procedure functionality depends mainly on the patient's age at initial reconstruction.

In vitro Growth Pattern of Primary Human Osteoblasts on Calcium Phosphate- and Polymethylmethacrylate-Based Bone Cement.

BACKGROUND/PURPOSE: Polymethylmethacrylate (PMMA) and calcium phosphate (Ca-P) cements are widely used for arthroplasty surgery and augmentation of bone defects. However, aseptic implant loosening in absence of wear-induced osteolysis indicates an unfavourable interaction between the cement surface and human osteoblasts. Our underlying hypothesis is that cement surfaces directly modify cell viability, proliferation rate, and cell differentiation. METHODS: To test this hypothesis, we examined primary human osteoblasts harvested from six individuals. These cells were pooled and subsequently seeded directly on cement pellets prepared from Palacos® R, Palacos® R+G, and Norian® Drillable cements. After incubation for 24 and 72 h, cell viability, proliferation rate, apoptosis rate, and cell differentiation were analysed. RESULTS: Upon cultivation of human osteoblasts on cement surfaces, we observed a significantly reduced cell viability and DNA content compared to the control. Analysis of the apoptosis rate revealed an increase for cells on Palacos R and Norian Drillable, but a significant decrease on Palacos R+G compared to the control. Regarding osteogenic differentiation, significantly lower values of alkaline phosphatase enzyme activity were identified for all cement surfaces after 24 and 72 h compared to cultivation on tissue culture plastic, serving as control. CONCLUSIONS: In summary, these data suggest a limited biocompatibility of both PMMA and Ca-P cements, necessitating further research to reduce unfavourable cell-cement interactions and consequently extend implant survival.

Short- to long-term follow-up of total femoral replacement in non-oncologic patients.

BACKGROUND: Compromised bone stock and heavily impaired structural integrity after multiple endoprosthetic revision surgeries can lead to a comparable condition as encountered in musculoskeletal tumor surgery. Total femoral replacement (TFR) can restore femoral integrity and allow patients to resume ambulation. Even though several authors reported their results of TFR, so far many questions are still on debate: Which patients are at risk to experience low functional outcome? Do complications and clinical outcome after TFR depend on the indication for the surgery (e.g. periprosthetic fractures or aseptic loosening) or the age of the patients? The purpose of the present study was to compare complication rates after TFR performed with modular total femur prosthesis MML (Fa. ESKA/Orthodynamics) in patients without malignant disease. METHODS: We conducted a retrospective chart review and functional investigation of patients treated with a TFR for non-oncologic conditions from 1995 to 2015 and a minimum follow-up of 2 years. Complications were recorded according to the Henderson-Classification; outcome was evaluated with established clinical scores. The indication for TFR was periprosthetic fracture (Group A, n = 11) or aseptic loosening (Group B, n = 7) with massive bone defect of the femur deemed unsuitable for conventional arthroplastic or biologic reconstruction. RESULTS: Eighteen patients matched the inclusion criteria and could be investigated clinically after a mean follow-up of 80 months (range: 28-132). Before TFA, all patients had previously undergone multiple operations (range: 1-8). The overall failure rate for any reason was 72% (n = 13/18), leading to a total of 37 surgical revisions with total exchange of TFR in 22% (n = 4/18). Most common failure mechanism was Type I (soft tissue), followed by Type IV (infection) and Type III (mechanical failure). According to Enneking's functional evaluation method (MSTS-Score), the function ranged from 1 to 15 with a mean of 10 ± 4 out of 30. CONCLUSION: TFR is a salvage procedure to restore mechanical integrity and regain functional ability after extensive femoral bone loss. Outcome of the patients in the present study did mainly depend on the age at reconstruction and not on the indication for TFR.

Glucosamine sulfate suppresses the expression of matrix metalloproteinase-3 in osteosarcoma cells in vitro.

BACKGROUND: Glucosamine, a common dietary supplement, has a possible anti-sarcoma effect. However, an understanding of the underlying mechanism of such an effect is limited. For this study we hypothesized that glucosamine suppresses the basal level of matrix metalloproteinase expression in human osteosarcoma cell lines. METHODS: We examined the osteosarcoma cell lines, MG-63 and SaOS-2. Cells were exposed to 0, 10, 50 and 100 µg/ml glucosamine sulfate for 48 h and treatment toxicity was determined through measurement of cell viability and proliferation. Relative gene expression of matrix metalloproteinase (MMP)-2, -3 and -9 was quantified by real-time polymerase chain reaction. Protein levels of MMP-2 and -9 were assessed by ELISA. RESULTS: Administration of 10, 50 or 100 µg/ml glucosamine sulfate had no effect on the cell viability of MG-63 and SaOS-2 cells. A significant reduction of MMP expression in both cell lines was observed only for MMP-3, while a decrease in MMP-9 was seen in SaOS-2 cells. The expression of MMP-2 was not significantly affected in either cell line. Protein level of MMP-3 was reduced in both cell lines upon stimulation with 10 µg/ml glucosamine sulfate whereas for MMP-9 a decrease could only be observed in SaOS-2 cells. CONCLUSION: In this study, we found a pronounced suppressive effect of glucosamine sulfate particularly on MMP-3 and also MMP-9 mRNA and protein levels in osteosarcoma cell lines in vitro. The data warrants further investigations into the potential anti-tumor efficacy of glucosamine sulfate in osteosarcoma.

Management of musculoskeletal tumors during pregnancy: a retrospective study.

BACKGROUND: In recent years, scientific research has increasingly focused on malignancies during pregnancy. However, the development of musculoskeletal tumors during pregnancy has only been the subject of a few studies so far. The primary aim of this study was to identify the incidence of sarcomas during pregnancy at our musculoskeletal tumor center (MSTC). Secondarily we intended to analyze these cases and discuss possible recommendations regarding diagnostic work-up as well as therapy on the basis of the literature. METHODS: All female patients who had been treated for soft tissue or bone sarcoma at our academic MSTC in the period between the years 2002 and 2010 were screened retrospectively for anamnestic annotations of pregnancy or records of pregnancy in the obstetrical database of our university hospital. The patients who met the criteria for inclusion (diagnosed sarcoma and pregnancy) were enrolled. For every pregnant patient two age-matched female control patients that suffered from tumors with the same histologic type were included. RESULTS: In the period between 2002 and 2010, 240 female patients between the age of 16 and 45 were treated for sarcoma. In eight out of the 240 cases the tumor disease developed or progressed during pregnancy. The delay in diagnosis was approximately eight months and turned out to be significantly higher for pregnant patients compared to non- pregnant controls. Each woman's tumor was misdiagnosed at least once. CONCLUSIONS: Diagnostic follow-up of pregnant women presenting with a growing or painful mass, which is suspected to be a musculoskeletal tumor, should be performed at a specialized tumor center. We recommend a multidisciplinary approach and discussing all possible consequences for mother and child intensively in accordance with the available literature.

Long-term functional outcome and quality of life following rotationplasty for treatment of malignant tumors.

BACKGROUND: Malignant bone tumors of the lower extremity are more frequently found in children and adolescents than in adults. Modern treatment regimens led to high limb salvage rates and offer the choice between endoprosthetic replacement and rotationplasty in many cases. Rotationplasty has proven to be an effective, highly functional option in short- and mid-term studies. Aim of this study was to assess long-term results regarding quality of life and functionality after rotationplasty and to compare the obtained results to a representative healthy German sample cohort. METHODS: In total 12 patients who underwent rotationplasty between 1991 and 2001 were enrolled in this study. After physical examination, they were evaluated regarding health related quality of life, functional outcome and psychosocial status. While quality of life was mainly assessed using the SF-36 (The Short Form (36) Health Survey v2), functional outcome was measured using the musculoskeletal tumor society score (MSTS) as well as the Tegner activity level scale. RESULTS: Average age at the time of surgery was 19 ± 10 year. and 32 ± 11 year. at the time of follow up. Mean follow-up was 14 ± 9 years. The SF-36 scores accounted for 80.4 ± 15.7 regarding physical functioning, for 78.1 ± 24.1 regarding the physical role functioning, for 74.1 ± 17.6 regarding bodily pain and for 71.8 ± 26.1 regarding general health. SF-36 score for vitality was 75.0 ± 12.8, for social functioning 98.9 ± 3.6, 88.2 ± 23.9 for emotional role functioning and 89.6 ± 10.1 for the mental health. Comparison to a representative German sample cohort revealed significantly higher patient's scores for vitality, social functioning and mental health (p < 0.05). The overall MSTS resulted in an average of 64 ± 12 % and the Tegner activity level scale accounted for 4.1 ± 0.6 pts. CONCLUSIONS: The presented long-term results indicate that rotationplasty provides a high quality of life. Patients are satisfied with a good functional outcome regarding activities of daily life and even sports.

Unicameral Bone Cyst in the Calcaneus of Mirror Image Twins.

Unicameral bone cysts (UBCs) are benign tumor-like lesions that commonly occur in the diaphyseal or metaphyseal region of the long bones within the first 2 decades of life. Until today, the pathogenesis of UBC has been unclear, but mechanisms such as vascular occlusion or a response to trauma have been supposed. During the past decade, in particular, the genetic aspects of the development of this rare lesion have been discussed. We present the first case of mirror image monozygotic twins with a mirror image UBC of the calcaneus. Our findings reinforce the importance of additional studies to understand the significance of cytogenetic factors in the etiology of UBC.