Prognostic value of clinical and MRI features in the screening of lipomatous lesions.

BACKGROUND AND OBJECTIVES: Differentiation of lipomatous tumors mostly requires diagnostic biopsy but is essential to decide for the most adequate therapy. This study aims to investigate the prognostic value of available clinical and radiological features with regard to malignancy of the lesion, recurrence and survival. METHODS: In this retrospective cohort study, 104 patients with a biopsy-proven lipomatous tumor between 2010 and 2015 and a minimum clinical follow-up of two years were enrolled. Next to clinical features (age, gender, location of the lesion, histopathologic diagnosis, stage of disease, time to recurrence and death), MRI parameters were recorded retrospectively and blinded to the histological diagnosis. RESULTS: Malignant lipomatous tumors were associated with location in the lower extremities and MRI features like thick septation (>2 mm), presence of a non-adipose mass, foci of high T2/STIR signal and contrast agent enhancement. A non-adipose mass was a predictor for recurrence and inferior overall survival, while lesions with high T2/STIR signal showed higher risk of recurrence only. In combination, clinical and radiological features (lower extremities, septation > 2 mm, existence of non-adipose mass, contrast enhancement, and foci of high T2/STIR signal) predicted a malignant lipomatous tumor with an accuracy of 0.941 (95% CI of 0.899-0.983; 87% sensitivity, 86% specificity). CONCLUSION: Localization and characteristic MR features predict malignancy in most lipomatous lesions. Non-adipose masses are a poor prognostic factor, being associated with tumor recurrence and disease-related death.

The effect of preoperative radiotherapy on surgical resectability, tumor volume and the necrosis rate of soft tissue sarcomas: A retrospective single-center analysis.

INTRODUCTION: The mainstay of soft tissue sarcoma treatment is limb preserving resection, often combined with radiotherapy, preferably preoperative radiotherapy. The goal of this study is to retrospectively assess the effect of preoperative (neoadjuvant) radiotherapy on the minimal distance to critical neurovascular structures, on tumor volume and the necrosis rate. MATERIAL AND METHODS: The data of fifty-one patients treated for a localized soft tissue sarcoma (STS) of the extremity or the trunk were retrospectively reviewed. All patients were analyzed with MR imaging before and after preoperative radiotherapy to determine the impact of radiotherapy on the precise planning and execution of the surgical excision of the tumor. The volume of the tumor as well as the distance to anatomically relevant structures were measured on MRI. Tumor type, characteristics and necrosis rate were obtained from the pathology report. RESULTS: At latest follow-up (median 51 months (range 6-113)) 32/51 (63%) patients were alive. The minimal distance between the myxoid liposarcomas (n = 12) and the vessels was significantly increased by preoperative radiotherapy from 1.09 mm [0-21.1] to 5.23 mm [0-32.70] (P = 0.045). High-grade tumors showed a significant increase in tumor volume after irradiation (p = 0.03) and a significantly greater necrosis rate than low-grade tumors (p < 0.001). CONCLUSION: Preoperative radiotherapy significantly increases the minimal distance from myxoid liposarcomas to the vessel. In the subgroup of STS that demonstratea volume reduction the distance to nerves and vessels increases, but with the low number of cases, this increase is not statistically significant. The effect of preoperative radiotherapy on the tumor volume varies greatly, whereas the subtype of myxoid liposarcoma shows a significant volume reduction in all cases.

When SUV Matters: FDG PET/CT at Baseline Correlates with Survival in Soft Tissue and Ewing Sarcoma.

INTRODUCTION: The role of positron-emission tomography/computed-tomography (PET/CT) in the management of sarcomas and as a prognostic tool has been studied. However, it remains unclear which metric is the most useful. We aimed to investigate if volume-based PET metrics (Tumor volume (TV) and total lesions glycolysis (TLG)) are superior to maximal standardized uptake value (SUVmax) and other metrics in predicting survival of patients with soft tissue and bone sarcomas. MATERIALS AND METHODS: In this retrospective cohort study, we screened over 52'000 PET/CT scans to identify patients diagnosed with either soft tissue, bone or Ewing sarcoma and had a staging scan at our institution before initial therapy. We used a Wilcoxon signed-rank to assess which PET/CT metric was associated with survival in different patient subgroups. Receiver-Operating-Characteristic curve analysis was used to calculate cutoff values. RESULTS: We identified a total of 88 patients with soft tissue (51), bone (26) or Ewing (11) sarcoma. Median age at presentation was 40 years (Range: 9-86 years). High SUVmax was most significantly associated with short survival (defined as <24 months) in soft tissue sarcoma (with a median and range of SUVmax 12.5 (8.8-16.0) in short (n = 18) and 5.5 (3.3-7.2) in long survival (≥24 months) (n = 31), with (p = 0.001). Similar results were seen in Ewing sarcoma (with a median and range of SUVmax 12.1 (7.6-14.7) in short (n = 6) and 3.7 (3.5-5.5) in long survival (n = 5), with (p = 0.017). However, no PET-specific metric but tumor-volume was significantly associated (p = 0.035) with survival in primary bone sarcomas (with a median and range of 217 cm3 (186-349) in short survival (n = 4) and 60 cm3 (22-104) in long survival (n = 19), with (p = 0.035). TLG was significantly inversely associated with long survival only in Ewing sarcoma (p = 0.03). DISCUSSION: Our analysis shows that the outcome of soft tissue, bone and Ewing sarcomas is associated with different PET/CT metrics. We could not confirm the previously suggested superiority of volume-based metrics in soft tissue sarcomas, for which we found SUVmax to remain the best prognostic factor. However, bone sarcomas should probably be evaluated with tumor volume rather than FDG PET activity.

Pelvic Chondrosarcoma Treated by En Bloc Resection with Patient-Specific Osteotomy Guides and Reimplantation of the Extracorporeally Irradiated Bone as an Osseocartilaginous Structural Orthotopic Autograft: A Report of Two Cases with Description of the Surgical Technique.

Primary tumors of the pelvis are considered difficult to treat due to the complex anatomy and the proximity of important neurovascular structures. The surgical armamentarium for the treatment of these tumors has evolved with the help of cutting-edge technology from debilitating hemipelvectomies to solutions such as precise resections guided by patient-specific instruments or computer navigation and reconstruction by modular prostheses, 3D-printed custom-made implants, or orthotopic autograft reimplantation after extracorporeal irradiation. Different combinations of these techniques have been described in the literature with various rates of success. We present two cases of pelvic chondrosarcomas successfully treated by a combination of periacetabular resection with patient-specific osteotomy guides and orthotopic reimplantation of the extracorporeally irradiated autograft resulting in retention of the native hip.

Extra-abdominal desmoid tumor fibromatosis: a multicenter EMSOS study.

BACKGROUND: Extra-abdominal desmoid tumor fibromatosis (DTF) is a rare, locally aggressive soft tissue tumour. The best treatment modality for this patient cohort is still object of debate. QUESTIONS/PURPOSE: This paper aimed to (1) to compare the outcomes of DTF after different treatment modalities, (2) to assess prognostic factors for recurrence following surgical excision, and (3) to assess prognostic factors for progression during observation. METHODS: This was a retrospective multicenter study under the patronage of the European Musculoskeletal Oncology Society (EMSOS). All seven centres involved were tertiary referral centres for soft tissue tumours. Baseline demographic data was collected for all patients as well as data on the diagnosis, tumour characteristics, clinical features, treatment modalities and whether they had any predisposing factors for DTF. RESULTS: Three hundred eighty-eight patients (240 female, 140 male) with a mean age of 37.6 (±18.8 SD, range: 3-85) were included in the study. Two hundred fifty-seven patients (66%) underwent surgical excision of ADF, 70 patients (18%) were observed without therapy, the residual patients had different conservative treatments. There were no significant differences in terms of tumour recurrence or progression between the different treatment groups. After surgical excision, younger age, recurrent disease and larger tumour size were risk factors for recurrence, while tumours around the shoulder girdle and painful lesions were at risk of progression in the observational group. CONCLUSION: Local recurrence rate after surgery was similar to progression rates under observation. Hence, observation in DTF seems to be justified, considering surgery in case of dimensional progression in 2 consecutive controls (3 and 6 months) and in painful lesions, with particular attention to lesions around the shoulder girdle.

The influence of different patient positions on the preoperative 3D planning for surgical resection of soft tissue sarcoma in the lower limb-a cadaver pilot study.

INTRODUCTION: Complete surgical resection remains the mainstay of the treatment of soft tissue sarcomas. Intraoperative positioning of the patient is dictated by tumor location, whereas preoperative imaging is always performed in the supine position. The effect of changing the patient position on the exact location of the tumor with regard to neurovascular structures and bone is unknown. MATERIAL AND METHODS: Two fresh frozen cadavers (pelvis and legs) were thawed and warmed. Three standardized tumor models were implanted in the thigh and calf. MR/CT images of the cadavers were obtained sequentially in four different patient positions. The minimal distance of each "tumor" to neurovascular structures was measured on axial MR images and the 3D shift of the center of the tumor to the bone was measured after segmentation of the CT images. RESULTS: A significant difference of the minimal distance of the "tumor" to the femoral artery (P = 0.019/0.023) and a significantly greater number of deviations of more than 5mm/10 mm in the thigh between the supine position and the other positions compared to two supine positions (p = 0.027/0.028) were seen. The center of the "tumor" compared to the bone shifted significantly in the thigh (P < 0.001/0.002) but not the lower leg. CONCLUSION: Obtaining images in the same patient position as the planned tumor resection may become particularly relevant if computer assisted surgery, which is based on preoperative imaging, is introduced into soft tissue sarcoma surgery as the patient position significantly influences the spatial position of the tumor.

The Accuracy of Three-Dimensional Planned Bone Tumor Resection Using Patient-Specific Instrument.

INTRODUCTION: Although treatment of bone tumors is multidisciplinary, the complete surgical resection of bone tumors remains the mainstay of the treatment. Patient-specific instruments (PSI) are personalized tools, which help the surgeon to perform tumor resections accurately. The aim of this study is to evaluate how precise the planned resection can be intraoperatively executed with the use of PSI. PATIENTS AND METHODS: Eleven patients who underwent a resection of bone tumor using PSI were analyzed. A preoperative model of the tumor and the affected bone was created from acquired CT scans and MRI. After defining the resection planes, PSI were produced by a 3D printer. The resected piece of bone was scanned and imported in the original planning model enabling the assessment of the distance between the planned resection plane and the realized osteotomy in every direction. RESULTS: In overall, the combined error of an osteotomy ranges from 0.74 ± 0.96 mm to 3.60 ± 2.46 mm. The average errors observed in situations with one resection plane (simple osteotomy) are lower than in complex curved osteotomies with multiple planes, in which we also found a greater variance. CONCLUSION: 3D planned bone tumor resections using PSI show promising results for precise resection at different anatomical regions. Even if the found error range in this series is slightly higher than reported, PSI remain a valuable tool to facilitate complex bone tumor resections.

Carbon Fiber/Polyether Ether Ketone (CF/PEEK) Implants Allow for More Effective Radiation in Long Bones.

BACKGROUND: Metallic implants show dose-modulating effects in radiotherapy and complicate its computed tomography (CT)-based planning. Dose deviations might not only affect the surrounding tissues due to backscattering and inadvertent dose increase but might also compromise the therapeutic effect to the target lesion due to beam attenuation. Later on, follow-up imaging is often obscured by metallic artefacts. Purposes: This study investigates the dosimetric impact of titanium and radiolucent carbon fiber/polyether ether ketone (CF/PEEK) implants during adjuvant radiation therapy in long bones. (1) Does the use of CF/PEEK implants allow for a more homogenous application of radiation? (2) Is the dose delivery to the target volume more efficient when using CF/PEEK implants? (3) Do CF/PEEK implants facilitate CT-based radiation therapy planning? Materials and methods: After CT-based planning, bone models of six ovine femora were irradiated within a water phantom in two immersion depths to simulate different soft-tissue envelopes. Plates and intramedullary nails of both titanium and CF/PEEK were investigated. Radiation dosage and distribution patterns were mapped using dosimetry films. Results: First, the planned implant-related beam attenuation was lower for the CF/PEEK plate (1% vs. 5%) and the CF/PEEK nail (2% vs. 9%) than for corresponding titanium implants. Secondly, the effective decrease of radiation dosage behind the implants was noticeably smaller when using CF/PEEK implants. The radiation dose was not significantly affected by the amount of surrounding soft tissues. A significant imaging artefact reduction was seen in all CF/PEEK models. Conclusion: CF/PEEK implants lead to a more reliable and more effective delivery of radiation dose to an osseous target volume. With regard to radiation therapy, the use of CF/PEEK implants appears to be particularly beneficial for intramedullary nails.

Diagnostic utility of perilesional muscle edema in myositis ossificans.

OBJECTIVES: To investigate the value of extensive perilesional muscle edema for the differentiation between myositis ossificans (MO) and malignant intramuscular soft tissue tumors on MRI. MATERIALS AND METHODS: Two blinded readers analyzed MR examinations of 90 consecutive patients with intramuscular soft tissue masses (group 1: MO, n = 20; group 2: malignant tumors, n = 70). Extent of edema around lesions was graded (0, none; 1, minimal edema; 2, moderate edema; 3, extensive edema). Edema-lesion ratio (ELR = ratio of the maximal diameter of the edema and the maximal diameter of the central lesion) was calculated. ROC analysis, Mann-Whitney U test, and Kappa test were used. RESULTS: A total of 70% and 60% of patients with MO had edema grade 3 (reader 1/reader 2), 30%/40% edema grade 2. For the patients with malignant tumors, it was 2.9%/1.4% (edema grade 3) and 16%/23% (edema grade 2). Interrater reliability was substantial (kappa = 0.66). Extent of edema was significantly higher for patients of group 1 (p < 0.0001, both readers). Mean ELR was 3.60 (group 1) and 1.35 (group 2), with statistically significant differences (p < 0.0001). Grade 3 edema showed a sensitivity/specificity of 70%/97.1% (reader 1) and 60%/99% (reader 2) for diagnosing MO. For ELR > 2.0, sensitivity was 90% and specificity 91% for diagnosing MO. CONCLUSIONS: Extensive perilesional muscle edema on MRI of more than double the size of the central lesion is highly specific, but not pathognomonic for myositis ossificans in the early/intermediate stage in the differentiation to malignant intramuscular soft tissue lesions.

Joint-preserving tumour resection around the knee with allograft reconstruction using three-dimensional preoperative planning and patient-specific instruments.

BACKGROUND: The region around the knee joint is a common location of malignant bone tumours. Limb salvage procedures, whenever possible, are preferred to amputation. Allograft reconstruction is an accepted procedure to restore large bone defects. Preoperative three-dimensional (3D) planning and patient-specific instruments (PSI) have already been introduced. The purpose of this study was to provide a technical guideline for joint preserving tumour resection and allograft reconstruction around the knee using 3D planning and PSI. MATERIAL AND METHODS: 3D triangular surface models are created based on computed tomography (CT) and magnetic resonance imaging (MRI) data, whereby tumour expansion in the bone and affection of the surrounding structures are assessed. We describe the preoperative 3D analysis and planning in tumours around the knee joint. In addition, we provide a description of different PSI as well as cutting-techniques to enlarge the toolkit and facilitate a broad range of joint preserving tumour resections with allograft reconstruction around the knee. The basic guide serves for the registration of the preoperative plan for the surgery. Reference pins facilitate the application of further guides. Different additional guide designs can be applied, such as "safety guides," "osteotomy guides," and "allograft adjustment guides." DISCUSSION: The use of 3D planning and generation of PSI offers valuable tools in tumour resection and allograft reconstruction around the knee joint. To perform complex osteotomies and to preserve vital structures PSI seems to be helpful tools. A step-by-step guideline is provided for the use of 3D preoperative planning and sequentially applied patient-specific guides.

On the biomechanical properties of osteosarcoma cells and their environment.

Although rare among the general population, bone malignancies have a high rate of incidence among children and adolescents and are associated with high mortality rates. Osteosarcoma (also known as osteogenic sarcoma) is the most frequent primary cancer of bone and shows a high tendency to metastasize to the lung. Despite the frequent use of osteosarcoma-derived cell lines in basic biomechanical research and for the evaluation of cell responses to new biomaterials, the mechanical phenotype and the differences between osteosarcoma cells and related cell types, such as mesenchymal cells, osteoblasts and osteocytes, remain largely unknown. In the present review we summarize current knowledge of the biophysical and mechanical properties of the niche of primary osteosarcomas and of the malignant cells, and discuss the impact of these features on the progression of malignancy.

The relationship between metastatic potential and in vitro mechanical properties of osteosarcoma cells.

Osteosarcoma is the most frequent primary tumor of bone and is characterized by its high tendency to metastasize in lungs. Although treatment in cases of early diagnosis results in a 5-yr survival rate of nearly 60%, the prognosis for patients with secondary lesions at diagnosis is poor, and their 5-yr survival rate remains below 30%. In the present work, we have used a number of analytical methods to investigate the impact of increased metastatic potential on the biophysical properties and force generation of osteosarcoma cells. With that aim, we used two paired osteosarcoma cell lines, with each one comprising a parental line with low metastatic potential and its experimentally selected, highly metastatic form. Mechanical characterization was performed by means of atomic force microscopy, tensile biaxial deformation, and real-time deformability, and cell traction was measured using two-dimensional and micropost-based traction force microscopy. Our results reveal that the low metastatic osteosarcoma cells display larger spreading sizes and generate higher forces than the experimentally selected, highly malignant variants. In turn, the outcome of cell stiffness measurements strongly depends on the method used and the state of the probed cell, indicating that only a set of phenotyping methods provides the full picture of cell mechanics.

Carbon fibre/polyether ether ketone (CF/PEEK) implants in orthopaedic oncology.

BACKGROUND: Radiation therapy is an important therapeutic element in musculoskeletal tumours, especially when encountering multiple or painful lesions. In osteolytic lesions, a surgical stabilization with implants is often required. However, metallic implants not only complicate the CT-based planning of a subsequent radiation therapy, but also have an uncontrollable dose-modulating effect in adjuvant radiotherapy. In addition, follow-up imaging and the diagnosis of local recurrences are often obscured by metallic artefacts. Radiolucent implants consisting of carbon/polyether ether ketone (CF/PEEK) therefore facilitate adjuvant radiation therapy and follow-up imaging of bone lesions. We hereby present clinical cases with application of CF/PEEK implants in orthopaedic tumour surgery. METHODS: We report a single-centre experience of three selected patients with surgical stabilization of osteolytic bone lesions using CF/PEEK implants. Detailed information about the clinical presentation, preoperative considerations, surgical procedures and postoperative results is provided for each case. RESULTS: One spinal lesion (T12 vertebral body), one lesion of the upper extremity (humerus) and one of the lower extremities (tibia) were surgically stabilized with use of CF/PEEK implants. With a mean follow-up of 12 months (range 6-25 months), no adverse events were observed. Two patients received adjuvant radiotherapy. Follow-up imaging was obtained in all patients. CONCLUSION: The applicability of CF/PEEK implants in orthopaedic tumour surgery is good with respect to postoperative follow-up imaging, application of adjuvant radiotherapy and intraoperative handling. As a result of the unique material properties, oncological patients might particularly benefit from CF/PEEK implants.

Allograft Reconstruction of the Extensor Mechanism after Resection of Soft Tissue Sarcoma.

INTRODUCTION: Soft tissue tumors around the knee joint still pose problems for the excision and subsequent reconstruction. METHODS: In the 6 included patients the soft tissue sarcoma has its base on the anterior surface of the extensor mechanism and expands towards the skin. The entire extensor apparatus (quadriceps tendon, patella, and patellar tendon) was resected and replaced by a fresh-frozen allograft. RESULTS: The mean follow-up was 6.7 years (range: 2-12.4 years). In two patients a local recurrence occurred, resulting in a 5-year local recurrence-free rate of 66.7% (95% CI: 19.5%-90.4%). Distant metastases were found in 4 patients resulting in a 5-year metastasis-free rate of 33.3% (95% CI: 4.6%-67.5%). Two patients underwent at least one revision surgery, including one patient in whom the allograft had to be removed. According to the ISOLS function score 24.7 points (range: 19-28 points) were achieved at the last follow-up. The mean active flexion of the knee joint was 82.5° (range: 25-120°) and a mean extension lag of 10° (range: 0-30°) was observed. CONCLUSIONS: The replacement of the extensor mechanism by an allograft is a reasonable option, allowing wide margins and restoration of active extension in most patients. TRIAL REGISTRATION: The presented study is listed on the ISRCTN registry with trial number ISRCTN63060594.

Magnetic Resonance Imaging-Based Grading of Cartilaginous Bone Tumors: Added Value of Quantitative Texture Analysis.

OBJECTIVES: The aim of this study was to assess the interreader agreement and diagnostic accuracy of morphologic magnetic resonance imaging (MRI) analysis and quantitative MRI-based texture analysis (TA) for grading of cartilaginous bone tumors. MATERIALS AND METHODS: This retrospective study was approved by our local ethics committee. Magnetic resonance imaging scans of 116 cartilaginous bone neoplasms were included (53 chondromas, 26 low-grade chondrosarcomas, 37 high-grade chondrosarcomas). Two musculoskeletal radiologists blinded to patient data separately analyzed 14 morphologic MRI features consisting of tumor and peritumoral characteristics. In addition, 2 different musculoskeletal radiologists separately performed TA including 19 quantitative TA parameters in a similar fashion. Interreader reliability, univariate, multivariate, and receiver operating characteristics analyses were performed for MRI and TA parameters separately and for combined models to determine independent predictors and diagnostic accuracy for grading of cartilaginous neoplasms. P values of 0.05 and less were considered statistically significant. RESULTS: Between both readers, MRI and TA features showed a mean kappa value of 0.49 (range, 0.08-0.82) and a mean intraclass correlation coefficient of 0.79 (range, 0.43-0.99), respectively. Independent morphological MRI predictors for grading of cartilaginous neoplasms were bone marrow edema, soft tissue mass, maximum tumor extent, and active periostitis, whereas TA predictors consisted of short-run high gray-level emphasis, skewness, and gray-level and run-length nonuniformity. Diagnostic accuracies for differentiation of benign from malignant as well as for benign from low-grade cartilaginous lesions were 87.0% and 77.4% using MRI predictors exclusively, 89.8% and 89.5% using TA predictors exclusively, and 92.9% and 91.2% using a combined model of MRI and TA predictors, respectively. For differentiation of low-grade from high-grade chondrosarcoma, no statistically significant independent TA predictors existed, whereas a model containing MRI predictors exclusively had a diagnostic accuracy of 84.8%. CONCLUSIONS: Texture analysis improves diagnostic accuracy for differentiation of benign and malignant as well as for benign and low-grade cartilaginous lesions when compared with morphologic MRI analysis.

Risks and benefits of combining denosumab and surgery in giant cell tumor of bone-a case series.

BACKGROUND: The RANK ligand inhibitor denosumab is being investigated for treatment of giant cell tumor of bone, but the available data in the literature remains sparse and controversial. This study analyzes the results of combining denosumab with surgical treatment and highlights possible changes for the oncologic surgeon in daily practice. METHODS: A total of 91 patients were treated surgically for giant cell tumor of bone between 2010 and 2014 in an institution, whereas 25 patients of the total additionally received denosumab and were part of this study. The average age of the patients was 35 years. Eleven patients received denosumab pre- and postoperatively, whereas with 14 patients, the denosumab treatment was applied either before (7 patients) or after (7 patients) the surgery. The average preoperative therapy duration was 3.9 months and the postoperative therapy 6 months by default. RESULTS: Sixteen patients presented a large tumor extension necessitating a resection of the involved bone or joint. In 10 of these patients, the indication for a resection procedure was abandoned due to the preoperative denosumab treatment and a curettage was performed. In the remaining six cases, the surgical indication was not changed despite the denosumab treatment, and two of them needed a joint replacement after the tumor resection. Also with patients treated with curettage, denosumab seems to facilitate the procedure as a new peripheral bone rim around the tumor was built, though a histologic analysis reveals viable tumor cells persisting in the denosumab-induced bone formation. After an average follow-up of 23 months, one histologically proven local recurrence occurred, necessitating a second curettage. A second patient showed a lesion in the postoperative imaging highly suspicious for local relapse which remained stable under further denosumab treatment. No adverse effect of the denosumab medication was observed in this study. CONCLUSIONS: Denosumab can be a help to the oncologic surgeon by reconstituting a peripheral rim and switching the stage from aggressive to active or latent disease. But as tumor cells remain in the new-formed bone, the surgical technique of curettage has to be changed from gentle to more aggressive to avoid higher local recurrence rates.

Tumor resection at the pelvis using three-dimensional planning and patient-specific instruments: a case series.

BACKGROUND: Sarcomas are associated with a relatively high local recurrence rate of around 30 % in the pelvis. Inadequate surgical margins are the most important reason. However, obtaining adequate margins is particularly difficult in this anatomically demanding region. Recently, three-dimensional (3-D) planning, printed models, and patient-specific instruments (PSI) with cutting blocks have been introduced to improve the precision during surgical tumor resection. This case series illustrates these modern 3-D tools in pelvic tumor surgery. METHODS: The first consecutive patients with 3-D-planned tumor resection around the pelvis were included in this retrospective study at a University Hospital in 2015. Detailed information about the clinical presentation, imaging techniques, preoperative planning, intraoperative surgical procedures, and postoperative evaluation is provided for each case. The primary outcome was tumor-free resection margins as assessed by a postoperative computed tomography (CT) scan of the specimen. The secondary outcomes were precision of preoperative planning and complications. RESULTS: Four patients with pelvic sarcomas were included in this study. The mean follow-up was 7.8 (range, 6.0-9.0) months. The combined use of preoperative planning with 3-D techniques, 3-D-printed models, and PSI for osteotomies led to higher precision (maximal (max) error of 0.4 centimeters (cm)) than conventional 3-D planning and freehand osteotomies (max error of 2.8 cm). Tumor-free margins were obtained where measurable (n = 3; margins were not assessable in a patient with curettage). Two insufficiency fractures were noted postoperatively. CONCLUSIONS: Three-dimensional planning as well as the intraoperative use of 3-D-printed models and PSI are valuable for complex sarcoma resection at the pelvis. Three-dimensionally printed models of the patient anatomy may help visualization and precision. PSI with cutting blocks help perform very precise osteotomies for adequate resection margins.

Two-month longitudinal study of mechanical properties of absorbable sutures used in orthopedic surgery.

BACKGROUND: This is the first study assessing the properties of large-diameter degradable sutures relevant for orthopedic applications over the course of in vitro incubation for 2 months. The data we present here provide guidance to the orthopedic surgeon in predicting the long-term performance of suture materials used everyday in surgical practice. METHODS: Five different absorbable (Vicryl, Maxon, Monocryl, PDS II, Vicryl rapide) and one non-absorbable (Ethibond) suture materials were tested. Measurements were made at five time points during the 56 days of incubation under physiological conditions (37.0 ± 0.02 °C; pH 7.4 ± 0.2). The following variables were recorded: load to failure, strain at maximal load as elongation normalized to original length, stiffness as the ratio of load to displacement on the linear proportion of the stress strain curve, and hysteresis as area under the curve of the stress strain curve. RESULTS: Vicryl was the strongest fiber on day 0 (195 N); however, by day 42, the tensile strength of the suture reduced to 14 N. Between days 14 and 28, PDS II (171 N) and Maxon (182 N) sustained the highest loads. Monocryl (p = 0.003) and Maxon (p < 0.001) showed an increasing strain with time, whereas Vicryl (p = 0.002) and Vicryl rapide (p = 0.007) revealed an increasing material stiffness. Furthermore, both Vicryl (p = 0.053) and Monocryl (p < 0.001) had an increasing hysteresis with ongoing degradation. Maxon, PDS II, and Ethibond showed stable material properties during the 2 months. CONCLUSIONS: The three absorbable sutures Vicryl, PDS II, and Maxon could sustain higher loads during the first 2 weeks than the non-absorbable Ethibond. Unexpectedly, Maxon and PDS II maintained their elastic properties in spite of their proceeding degradation and loss of tensile strength.

Allograft-prosthetic composite versus megaprosthesis in the proximal tibia-What works best?

Modular megaprosthesis (MP) and allograft-prosthetic composite (APC) are the most commonly used reconstructions for large bone defects of the proximal tibia. The primary objective of this study was to compare the two different techniques in terms of failures and functional results. A total of 42 consecutive patients with a mean age of 39.6 years (range 15-81 years) who underwent a reconstruction of the proximal tibia between 2001 and 2012 were included. Twenty-three patients were given an MP, and 19 patients received an APC. There were nine reconstruction failures after an average follow-up of 62 months: five in the MP group and four in the APC group (p=0.957). The 10-year implant survival rate was 78.8% for the MP and 93.7% for the APC (p=0.224). There were no relevant differences between the two groups in functional results. Both MP and APC are valid and satisfactory reconstructive options for massive bone defects in the proximal tibia. In high-demanding patients with no further risk factors, an APC should be considered to provide the best possible functional result for the extensor mechanism.

Modular megaprosthesis reconstruction for oncological and non-oncological resection of the elbow joint.

BACKGROUND: Reconstruction of large bone defects around the elbow joint is surgically demanding due to sparse soft tissue coverage, complex biomechanics and the close proximity to neurovascular structures. Modular megaprostheses are established reconstruction tools for the elbow, but only small case series have been reported in the literature. METHODS: Thirty-six patients who underwent reconstruction of the elbow joint with a modular megaprosthesis were reviewed retrospectively. In 31 patients (86.1%), elbow replacement was performed after resection of a bone tumour, whereas five non-oncological patients (13.9%) underwent surgery because of a previous failed elbow reconstruction. Functional outcome, rate of complications and oncological results were considered as primary endpoints. RESULTS: The mean follow-up was 25 months. The average achieved Mayo Elbow Performance Score (MEPS) was 77.08 (range 40-95) and the average Musculoskeletal Tumor Society (MSTS) score was 22.9 (range 8-30). Six complications (16.7%) were observed: two radial palsies, one temporary radial nerve dysfunction, one ulnar palsy, one disassembling of the articular prosthesis component and one deep infection necessitating the only implant removal. The overall 5-year survival rate of the patients was poor (25.1%) because of rapid systemic progression of the oncological disease in patients with metastatic lesion. However, the 5-year survival rate of the implant was very satisfactory (93%). CONCLUSIONS: Modular megaprosthesis is a reliable and effective reconstruction tool in large bone defects around the elbow joint. The complication rates are lower than seen in osteoarticular allografts and allograft-prosthesis composites while the functional outcome is equal. In palliative situations with metastatic disease involving the elbow, modular megaprosthesis enables rapid recovery and pain relief and preserves elbow function.