SMARCA2-NR4A3 is a novel fusion gene of extraskeletal myxoid chondrosarcoma identified by RNA next-generation sequencing.

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain differentiation, characterized by recurrent chromosomal translocation involving NR4A3 (9q22.33) in more than 90% of cases. Five fusion partners for NR4A3 have been described including: EWSR1 (22q12.2), TAF15 (17q12), FUS (16p11.2), TCF12 (15q21), and TFG (3q12.2). This report describes a patient with an EMC at the dorsum of the right foot. The tumor showed a cord-like and reticular pattern in a background of myxoid matrix. The tumor cells demonstrated an epithelioid morphology with prominent nucleoli. The tumor cells were positive for synaptophysin, GFAP, with focal positivity for CD117, S100, Cam5.2, and NSE, and negative for AE1/3, desmin, and SMA. An RNA next-generation sequencing test showed a SMARCA2-NR4A3 gene fusion which has not been previously reported. The exon 3 of SMARCA2 was fused to exon 3 of NR4A3. This fusion was confirmed by NR4A3 break-apart FISH, although both SMARCA2 (9p24.3) and NR4A3 (9q22.33) are located on chromosome 9. The tumor cells showed retained expression of INI1 and SMARCA2 by immunohistochemistry.

Second opinions in orthopedic oncology imaging: can fellowship training reduce clinically significant discrepancies?

OBJECTIVE: To determine factors that lead to significant discrepancies in second-opinion consultation of orthopedic oncology patients, and particularly if musculoskeletal fellowship training can decrease clinically significant discrepancies. METHODS: A PACS database was queried for secondary reads on outside cross-sectional imaging studies, as requested by orthopedic oncology from 2014 to 2017. Comparison of original and secondary reports was performed using a published seven-point scale that defines clinically significant discrepancies. An online search was performed for each original radiologist to record if a fellowship in musculoskeletal imaging was completed. Additionally, years of post-residency experience, number of Medicare part B patients billed per year (marker of practice volume), and average hierarchical condition category for each radiologist (marker of practice complexity) was recorded. RESULTS: A total of 571 patients met the inclusion criteria, with 184 cases initially interpreted by an outside fellowship trained musculoskeletal (MSK) radiologist and 387 cases initially interpreted by a non-MSK trained radiologist. The rate of clinically significant discrepancy was 9.2% when initially interpreted by MSK radiologists compared with 27.9% when initially performed by non-MSK radiologists (p < 0.05). After adjustment by both patient characteristics and radiologist characteristics, the likelihood of clinically significant discrepancies was greater for initial interpretations by non-MSK radiologists compared with MSK radiologists (OR = 1.36; 95% CI = 1.23-2.49). CONCLUSION: In orthopedic oncology patients, the rate of clinically significant discrepancies was significantly higher when initially interpreted by non-MSK radiologists compared with MSK radiologists. The lower rate of clinically significant discrepancies demonstrates that subspecialty training may direct more appropriate diagnosis and treatment.

Can Navigation-assisted Surgery Help Achieve Negative Margins in Resection of Pelvic and Sacral Tumors?

BACKGROUND: Navigation-assisted resection has been proposed as a useful adjunct to resection of malignant tumors in difficult anatomic sites such as the pelvis and sacrum where it is difficult to achieve tumor-free margins. Most of these studies are case reports or small case series, but these reports have been extremely promising. Very few reports, however, have documented benefits of navigation-assisted resection in series of pelvic and sacral primary tumors. Because this technology may add time and expense to the surgical procedure, it is important to determine whether navigation provides any such benefits or simply adds cost and time to an already complex procedure. QUESTIONS/PURPOSES: (1) What proportion of pelvic and sacral bone sarcoma resections utilizing a computer-assisted resection technique achieves negative margins? (2) What are the oncologic outcomes associated with computer-assisted resection of pelvic and sacral bone sarcomas? (3) What complications are associated with navigation-assisted resection? METHODS: Between 2009 and 2015 we performed 24 navigation-assisted resections of primary tumors of the pelvis or sacrum. Of those, four were lost to followup after the 2-year postoperative visit. In one patient, however, there was a failure of navigation as a result of inadequate imaging, so nonnavigated resection was performed; the remaining 23 were accounted for and were studied here at a mean of 27 months after surgery (range, 12-52 months). During this period, we performed navigation-assisted resections in all patients presenting with a pelvis or sacral tumor; there was no selection process. No patients were treated for primary tumors in these locations without navigation during this time with the exception of the single patient in whom the navigation system failed. We retrospectively evaluated the records of these 23 patients and evaluated the margin status of these resections. We calculated the proportion of patients with local recurrence, development of metastases, and overall survival at an average 27-month followup (range, 12-52 months). We queried a longitudinally maintained surgical database for any complications and noted which, if any, could have been directly related to the use of the navigation-assisted technique. RESULTS: In our series, 21 of 23 patients had a negative margin resection. In all patients the bone margin was negative, but two with sacral resections had positive soft tissue margins. Six of 23 patients experienced local recurrence within the study period. Three patients died during the study period. Seventeen patients demonstrated no evidence of disease at last recorded followup. We noted three intraoperative complications: one dural tear, one iliac vein laceration, and one bladder injury. Eight patients out of 23 had wound complications resulting in operative débridement. Two patients in the series developed transient postoperative femoral nerve palsy, which we believe were caused by stretch of the femoral nerve secondary to the placement of the reference array in the pubic ramus. CONCLUSIONS: Navigation-assisted resection of pelvic and sacral tumors resulted in a high likelihood of negative margin resection in this series, and we observed relatively few complications related specifically to the navigation. We have no comparison group without navigation, and future studies should indeed compare navigated with nonnavigated resection approaches in these anatomic locations. We did identify a potential navigation-related complication of femoral nerve palsy in this series and suggest careful placement and observation of the reference array during the operative procedure to lessen the likelihood of this previously unreported complication. We suggest it is worthwhile to consider the use of navigation-assisted surgery in resection of tumors of the pelvis and sacrum, but further study will be needed to determine its precise impact, if any, on local recurrence and other oncologic outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Analysis of a Steerable Needle for Fine Needle Aspiration and Biopsy: Efficiency and Radiation Dose Compared With a Conventional Straight Needle.

PURPOSE: Percutaneous computed tomography (CT)-guided needle biopsy has proven to be an efficacious method for sampling of many soft tissue lesions, especially deep-seated masses in the abdomen and pelvis. This study sought to test the potential for a novel steerable needle to improve localization and to reduce procedure duration and radiation dose compared with a conventional straight needle. MATERIAL AND METHODS: A fresh, raw meat sample (lean bovine flank) was imbedded with cylindrical radiopaque and radiolucent obstacles designed to simulate vessels (radiolucent objects) and bones (radiopaque objects) on CT. A pit-containing olive (partially radiopaque) was imbedded beyond the obstacles to represent the target. Two sites on the surface of the meat were selected and marked to determine initial needle placement. Two radiologists with different levels of experience proceeded to position a straight needle and the steerable needle from each skin site to the target using CT guidance as efficiently as possible, avoiding the obstacles. The total positioning time, the number of CT scans required for positioning, and the number of repositioning events (partial withdrawal followed by advancement) were tracked for the straight and steerable needles. RESULTS: For the straight needle, total time to reach the target was 499 to 667 seconds (mean, 592 seconds); for the steerable needle, total time to reach the target was 281 to 343 seconds (mean, 309 seconds), on average, 48% lower. The number of CT scans needed for needle positioning averaged 6.25 for the straight needle and 3.5 for the steerable needle, which is 44% lower. Repositioning events (withdrawing and readvancing the needle) ranged from 3 to 10 for the straight needle (mean, 6.5) and 0 for the steerable needle. CONCLUSIONS: Using an in vitro model embedded with obstacles, the steerable needle performed better than a straight needle with regard to procedure time, needle repositioning events, and CT scans required for placement.

Total joint arthroplasty in cancer patients.

Increasing numbers of total joint arthroplasty (TJA) patients have a history, or an active diagnosis, of cancer. We aimed to evaluate the risk of early postoperative complications in these patients. In our series, a history of malignancy was associated with an elevated risk of ischemic cardiac events and postoperative deep vein thrombosis (DVT), while active malignancy was associated with increased respiratory and renal complications, hematoma/seroma formation and early postoperative mortality. Both groups presented increased rates of overall in-hospital complications. Patients with bone metastasis to the hip demonstrated increased DVT and 90-day mortality rates. Cancer patients have increased morbidity and mortality after TJA and should undergo comprehensive medical optimization and adapted thromboprophylaxis.

Distal fibula metastasis of cholangiocarcinoma.

Cholangiocarcinoma is a rare disease with a reported incidence in the United States of 1 to 2 cases per 100,000 population. These cancers have a high mortality rate because most are locally advanced at presentation. Cholangiocarcinoma most commonly advances locally and regionally by invading the lymph nodes. In rare cases, it has been noted that cholangiocarcinoma can metastasize to bone, with a preponderance for the axial skeleton. Herein, we describe what we believe to be the first clinical report of an acral bone metastasis from metastatic cholangiocarcinoma.

Understanding the Effect of Osteoarthritis on Surgical Treatment Patterns, Healthcare Resource Utilization, and Costs Among Patients With Tenosynovial Giant Cell Tumors.

BACKGROUND: Tenosynovial giant cell tumor (TGCT) may be misdiagnosed as osteoarthritis (OA), or the chronic course of TGCT may lead to development of secondary OA. However, little is known about the effect of comorbid OA on long-term surgical patterns and costs among TGCT patients. METHODS: This cohort study used claims data from the Merative MarketScan Research Databases. The study included adults diagnosed with TGCT from January 1, 2014, to June 30, 2019, who have at least 3 years of continuous enrollment before and after the first TGCT diagnosis (date of the first TGCT diagnosis = index date) and no other cancer diagnosis during the study period. Patients were stratified by the presence of an OA diagnosis relative to the index date. Outcomes included surgical procedure patterns, healthcare resource utilization, and costs in the 3-year pre- and postindex periods. Multivariable models were used to assess the effect of OA on the study outcomes, controlling for baseline characteristics. RESULTS: The study included 2856 TGCT patients: 1153 (40%) had no OA before or after index (OA[-/-]), 207 (7%) had OA before index but not after (OA[+/-]), 644 (23%) had OA after index but not before (OA[-/+]), and 852 (30%) had OA before and after index (OA[+/+]). The mean age was 51.6 years, and 61.7% were female. During the postperiod, joint surgery was more common among OA(-/+) and OA(+/+) patients compared with OA(-/-) and OA(+/-) patients (55.7% vs 33.2%). The mean all-cause total costs in the 3-year postperiod were $19,476 per patient per year. Compared with OA(-/-) patients, OA(-/+) and OA(+/+) patients had a higher risk of undergoing recurrent surgery and higher total healthcare costs postindex. DISCUSSION: Higher rates of surgery and increased healthcare cost observed in TGCT patients with postindex OA underscore the need for effective treatment options to reduce joint damage, especially among patients with comorbid OA.

Comparison of Surface Area across the Allograft-Host Junction Site Using Conventional and Navigated Osteotomy Technique.

Bulk allograft reconstruction plays an important role in limb-salvage surgery; however, non-union has been reported in up to 27% of cases. The purpose of this study is to quantify average surface contact areas across simulated intraoperative osteotomies using both free-hand and computer-assisted navigation techniques. Pressure-sensitive paper was positioned between two cut ends of a validated composite sawbone and compression was applied using an eight-hole large fragment dynamic compression plate. Thirty-two samples were analyzed for surface area contact to determine osteotomy congruity. Mean contact area using the free-hand osteotomy technique was equal to 0.21 square inches. Compared with a control of 0.69 square inches, average contact area was found to be 30.5% of optimal surface contact. Mean contact area using computer-assisted navigation was equal to 0.33 square inches. Compared with a control of 0.76 square inches, average contact area was found to be 43.7% of optimal surface contact. Limited contact achieved using standard techniques may play a role in the high rate of observed non-union, and an increase in contact area using computer-assisted navigation may improve rates of bone healing. The development of an oncology software package and navigation hardware may serve an important role in decreasing non-union rates in limb salvage surgery.

Venous thromboembolism in musculoskeletal oncology surgery.

Venous thromboembolism (VTE), including both deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major complication of musculoskeletal surgery in general, and the risk is heightened in musculoskeletal oncology surgery. Despite the well-known association between cancer and VTE, the mechanism promoting this pathology is not entirely well understood. It is estimated that nearly all cancer patients will experience from some form of VTE, whether or not clinically relevant, during the course of their disease. Nonetheless, numerous studies have analyzed the occurrence and prevention of VTE in patients with cardiovascular disease or suffering trauma, but very few have specifically examined the safety or efficacy of preventing VTE in cancer patients with metastatic skeletal disease. This review will examine the various types of prophylactic treatment, timing of administration, risk stratification for determining the appropriate course of anticoagulation (AC), and discuss current views on chemical prophylaxes relativity to wound complications and excessive bleeding in orthopedic oncology patients. Overall, careful choice of anticoagulant and timing of administration must be made in order to avoid bleeding complications. A risk stratification system to determine which chemical prophylaxis to administered could be beneficial in both reducing the occurrence of VTE and decreasing associated wound complications or mortality. Further study should be conducted to tailor chemical prophylaxes recommendations to this largely affected population and effectively reduce the occurrence of VTE.

Erratum: Author Correction: Surgical Treatment Patterns, Healthcare Resource Utilization, and Economic Burden in Patients with Tenosynovial Giant Cell Tumor Who Underwent Joint Surgery in the United States.

[This corrects the article DOI: 10.36469/jheor.2022.32485.].

Surgical Treatment Patterns, Healthcare Resource Utilization, and Economic Burden in Patients with Tenosynovial Giant Cell Tumor Who Underwent Joint Surgery in the United States.

Background: Tenosynovial giant cell tumors (TGCT) are rare and locally aggressive neoplasms in synovium, bursae, and tendon sheaths, which cause pain, joint dysfunction, and damage to the affected joints. Objective: To evaluate the surgical patterns and economic burden among patients with TGCT who underwent joint surgery in the United States. Methods: Patients newly diagnosed with TGCT, aged 18-64 years, who underwent joint surgery post-TGCT diagnosis were identified from the OptumHealth Care Solutions, Inc database (Q1/1999-Q1/2017). Patients were required to be continuously enrolled for ≥1 year before and ≥3 years after the first TGCT diagnosis (index date). Surgical patterns were assessed post-index. Healthcare resource utilization and associated healthcare costs, and indirect costs related to work loss in year 1, year 2, and year 3 post-index, were compared with those at baseline. Results: Of 835 eligible TGCT patients, 462 (55%) patients who had ≥1 joint surgery post-index were included. During a median follow-up of 5.7 years, 78% of patients underwent their first joint surgery in year 1 and 41% had ≥1 repeat surgery. Magnetic resonance imaging utilization was highest during baseline (46%) and declined afterward (28%, 17%, and 19% in years 1, 2, and 3, respectively). Opioids and nonsteroidal anti-inflammatory drugs (NSAIDs), and physical therapy, occupational therapy, and rehabilitation services, were commonly used during baseline (45%, 40%, and 30%, respectively). More patients used opioids in year 1 vs baseline (78% vs 45%; P<0.0001), while its utilization return to baseline levels in year 2 (41%) and year 3 (42%). A similar pattern was observed for NSAIDs and physical/occupational therapy/rehabilitation services. Healthcare resource utilization and associated healthcare costs surged in year 1 and returned to baseline or lower in years 2 and 3. A similar pattern was observed for indirect costs associated with work loss. Discussion: The high proportion of patients undergoing repeat surgeries and prevalent use of opioids, NSAIDs, and physical/occupational therapy/rehabilitation services suggests an unmet medical need after surgical treatment. Conclusions: Surgical resection alone might be inadequate to control TGCT. New treatment options may complement surgery and alleviate the clinical and economic burden experienced by patients with TGCT who had received prior surgery.

Epidemiology of bone metastases.

BACKGROUND: This study evaluated the incidence of de novo bone metastasis across all primary cancer sites and their impact on survival by primary cancer site, age, race, and sex. QUESTIONS/PURPOSES: Our objectives were (I) characterize the epidemiology of de novo bone metastasis with respect to patient demographics, (II) characterize the incidence by primary site, age, and sex (2010-2015), and (III) compare survival of de novo metastatic cancer patients with and without bone metastasis. METHODS: This is a retrospective, population-based study using nationally representative data from the Surveillance, Epidemiology, and End Results program, 2010-2015. Incidence rates by year of diagnosis, annual percentage changes, Kaplan-Meier, univariate and multiple Cox regression models are included in the analysis. RESULTS: Of patients with cancer in the SEER database, 5.1% were diagnosed with metastasis to bone, equaling ~18.8 per 100,000 bone metastasis diagnoses in the US per year (2010-2015). For adults >25, lung cancer is the most common primary site (2015 rate: 8.7 per 100,000) with de novo bone metastases, then prostate and breast primaries (2015 rates: 3.19 and 2.38 per 100,000, respectively). For patients <20 years old, endocrine cancers and soft tissue sarcomas are the most common primaries. Incidence is increasing for prostate (Annual Percentage Change (APC) = 4.6%, P < 0.001) and stomach (APC = 5.0%, P = 0.001) cancers. The presence of de novo bone metastasis was associated with a limited reduction in overall survival (HR = 1.02, 95%, CI = [1.01-1.03], p < 0.001) when compared to patients with other non-bone metastases. CONCLUSION: The presence of bone metastasis versus metastasis to other sites has disease site-specific impact on survival. The incidence of de novo bone metastasis varies by age, sex, and primary disease site.

Nonoperative versus prophylactic treatment of bisphosphonate-associated femoral stress fractures.

BACKGROUND: Several studies have identified a specific fracture in the proximal diaphysis of the femur in patients treated with bisphosphonates. The fractures typically are sustained after a low-energy mechanism with the presence of an existing characteristic stress fracture. However, it is unclear whether these patients are best treated nonoperatively or operatively. QUESTIONS/PURPOSES: What is the likelihood of nonoperatively treated bisphosphonate-associated femoral stress fractures progressing to completion and during what time period? If prophylactic fixation is performed, do patients have a shorter hospital length-of-stay compared with patients having surgical fixation after fracture completion? PATIENTS AND METHODS: We retrospectively searched for patients older than 50 years receiving bisphosphonate therapy, with either incomplete, nondisplaced stress fractures or completed, displaced fractures in the proximal diaphysis of the femur between July 2002 and April 2009. After applying exclusion criteria, we identified 34 patients with a total of 40 bisphosphonate-associated fractures. The average duration of bisphosphonate use was 77 months. Twenty-eight of 40 (70%) fractures were completed, displaced fractures. Six of the 12 nondisplaced stress fractures initially were treated nonoperatively. The remaining six stress fractures were treated with prophylactic cephalomedullary nail fixation. The minimum followup was 12 months (mean, 36.5 months; range, 12-72 months). RESULTS: Five of the six stress fractures treated nonoperatively progressed to fracture completion and displacement at an average of 10 months (range, 3-18 months). The average hospital stay was 3.7 days for patients treated prophylactically and 6.0 days for patients treated after fracture completion. CONCLUSIONS: Our data suggest nonoperative treatment of bisphosphonate-related femoral stress fractures is not a reliable way to treat these fractures as the majority progress to fracture completion. Prophylactic fixation of femoral stress fractures also reduces total hospital admission time. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Arthroscopic Versus Open Management of Diffuse-Type Tenosynovial Giant Cell Tumor of the Knee: A Meta-analysis of Retrospective Cohort Studies.

BACKGROUND: Whether arthroscopic or open surgical management for diffuse-type tenosynovial giant cell tumor (D-TGCT) of the knee is associated with a lower rate of recurrence is unknown. METHODS: PubMed, Scopus, Web of Science, Cochrane, and EMBASE were searched on December 3, 2020. Retrospective studies that reported on recurrence rates for arthroscopic versus open management of D-TGCT were included. A total of 16 studies evaluating 1143 patients with D-TGCT of the knee were included (nopen = 551, narthroscopic = 350 patients, and narthroscopic/open = 23 patients). Random-effects meta-analyses were used to summarize and compare the reported recurrence rates, stratified by approach and overall recurrence. The meta-analysis was registered with PROSPERO. RESULTS: The recurrence rate per year (incidence) for arthroscopic procedures was 0.11 (95% CI 0.08 to 0.16, P < 0.0001) and for open procedures was 0.07 (95% CI 0.04 to 0.13, P < 0.0001). There was a 1.56 times (95% CI 1.04 to 2.34, P = 0.0332) increased risk of recurrence when treating D-TGCT of the knee with an arthroscopic approach. When evaluating only the subset of studies that had data for both arthroscopic and open approaches, the incidence rate per year for arthroscopic procedures was 0.17 (95% CI 0.11 to 0.27, P < 0.0001) and for open procedures was 0.11 (95% CI 0.06 to 0.19, P < 0.0001). The rate of overall complications was 0.04 (95% CI 0.01 to 0.08, P < 0.0001). CONCLUSION: Arthroscopic surgical management of D-TGCT of the knee in our study resulted in a 1.56 times risk of recurrence as compared with the open approach. The percent of overall complications was minimal.

The Economic Burden of Tenosynovial Giant Cell Tumors Among Employed Workforce in the United States.

OBJECTIVE: To assess the economic burden of tenosynovial giant cell tumor (TGCT) among US employed workforce. METHODS: Patients with TGCT medical claims (N = 1395) and matched controls (1:10) without TGCT claims (N = 13,950) were identified from the OptumHealth Care Solutions, Inc. database (January 1, 1999 to March 31, 2017). Adjusted regression models were used to compare healthcare resource utilization, time lost from work, and associated costs between cohorts. RESULTS: In patients with TGCT, the rates of inpatient admissions, emergency room visits, outpatient visits, and work loss days were 2.8, 1.5, 2.2, and 2.6 times those of matched controls, respectively (all P < 0.001). Total annual all-cause healthcare costs and work loss-related costs were $9368 and $2708 higher for TGCT patients than for matched controls, respectively (all P < 0.001). CONCLUSIONS: TGCT was associated with a significant healthcare and work loss burden on US employers.

Survival and Prognosis of Chondrosarcoma Subtypes: SEER Database Analysis.

Chondrosarcomas are rare tumors and, historically, investigation of these tumors has been limited to small series and single-institution studies. There have been no studies that evaluated the identification or comparison of differences in prognostic factors between the five known non-conventional chondrosarcoma subtypes (myxoid, juxtacortical, clear-cell, mesenchymal, and dedifferentiated). The purpose of this paper was to determine the demographic, clinical, incidence, and tumor characteristics of all five known non-conventional chondrosarcoma subtypes, determine the 1-, 5-year, and median survival differences between these subtypes, and to determine the demographic and clinical variables that are significant prognostic indicators for each chondrosarcoma subtypes. We retrospectively reviewed the SEER database for all patients with non-conventional chondrosarcoma. χ2 testing was used for correlations between clinical variables. Kaplan-Meier and Cox proportional hazard analysis were used to compare survival of the subtypes, and to assess the prognostic value of age group, race, sex, grade, anatomic location, and metastatic involvement. Several demographic characteristics including gender, race, age, and grade varied between chondrosarcoma subtypes. The tumor characteristics showed marked differences in presence of metastasis on presentation between the subtypes with increasing order of rate of metastasis with juxtacortical (2.1%), clear cell (5.7%), myxoid (7.6%), mesenchymal (10.6%), and the highest in dedifferentiated (19.8%). One-, 5-year, and median survival differed significantly between chondrosarcomas subtypes. The highest median survival was found in the juxtacortical subtype (97 months), followed by clear cell (79 months), myxoid (60 months), mesenchymal (33.5 months), and lowest in dedifferentiated (11 months). The only prognostic variable that was shown to significantly impact the survival of each non-conventional chondrosarcoma subtype was a metastatic disease at diagnosis (p = 0.03 to p < 0.001). Subtyping classification of chondrosarcoma should be made whenever possible, given differences in survival and prognostic factors between chondrosarcoma subtypes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:311-319, 2020.

Proximal tibial replacement in revision knee arthroplasty for non-oncologic indications.

Proximal tibial metaphyseal bone loss compromises the alignment and fixation of components during revision total knee arthroplasty. In massive, segmental defects with loss of collateral ligamentous support and lack of bone to support the use of prosthetic augments or metaphyseal cones or sleeves, a hinged proximal tibial replacement or a so-called "megaprosthesis" should be available. While proximal tibial replacement is the reconstructive method of choice in the setting of bone tumor resection, applications in non-oncologic joint arthroplasty are rare and may offer an opportunity for limb salvage in dire clinical scenarios with massive proximal tibial bone loss. This report reviews 6 cases of proximal tibial replacement.

Translocase of the outer mitochondrial membrane complex subunit 20 (TOMM20) facilitates cancer aggressiveness and therapeutic resistance in chondrosarcoma.

Chondrosarcoma is the second most common primary bone malignancy, representing one fourth of all primary bone sarcomas. It is typically resistant to radiation and chemotherapy treatments. However, the molecular mechanisms that contribute to cancer aggressiveness in chondrosarcomas remain poorly characterized. Here, we studied the role of mitochondrial transporters in chondrosarcoma aggressiveness including chemotherapy resistance. Histological grade along with stage are the most important prognostic biomarkers in chondrosarcoma. We found that high-grade human chondrosarcoma tumors have higher expression of the mitochondrial protein, translocase of the outer mitochondrial membrane complex subunit 20 (TOMM20), compared to low-grade tumors. TOMM20 overexpression in human chondrosarcoma cells induces chondrosarcoma tumor growth in vivo. TOMM20 drives proliferation, resistance to apoptosis and chemotherapy resistance. Also, TOMM20 induces markers of epithelial to mesenchymal transition (EMT) and metabolic reprogramming in these mesenchymal tumors. In conclusion, TOMM20 drives chondrosarcoma aggressiveness and resistance to chemotherapy.

Effect of Mitomycin C on recurrence of plantar fibromas.

Although certainly not the first line treatment for plantar fibromas, surgical resection is a treatment option for some patients with have failed exhaustive non-surgical treatment. The use of topical Mitomycin C has been recently shown to reduce the recurrence rate of other fibrous lesions. The purpose of this study was to determine the impact of topical application of Mitomycin C on recurrence rate of plantar fibromas. A retrospective analysis was done from a prospectively gathered database with a total 50 consecutive patients over a 16-month study period. The control group (n = 29) consisted of patients who underwent only surgical resection, while the study group (n = 21) consisted of patients who underwent surgical resection with adjuvant therapy using Mitomycin C. The primary endpoint was local recurrence after the procedure. Secondary end points included complications and toxicity associated with this medication. No patients were lost to follow up. Of the 29 patients in the control group, there were 17 patients (17/29, 58.6%) had recurrence of the plantar fibroma at a mean follow-up of 9.1 months. In contrast, in the experimental study group, all patients were free from local recurrence. No complications or side effects were associated with Mitomycin C use. The results demonstrate that the topical application of Mitomycin C to the tumor bed after surgical resection of plantar fibromas reduced the recurrence rate. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2554-2561, 2018.