e23506 Background: Chondroblastoma is a benign bone tumor with rare potential for pulmonary metastasis. The true incidence of lung metastasis remains uncertain due to inconsistent surveillance practices. We sought to determine the rate of pulmonary metastasis in chondroblastoma and characterize current chest imaging practices using an institutional cohort and literature meta-analysis. Methods: We conducted a retrospective review (2010-2025) of 19 chondroblastoma patients at our institution and stratified them by whether chest imaging was obtained. A meta-analysis of 23 published studies comprising 411 chondroblastoma patients was also conducted. Primary outcomes were pulmonary metastasis and mortality. Imaging utilization and clinical characteristics were compared between cohorts. Results: Sex distribution was nearly identical between both groups (institutional 62.3% male vs literature 65.9% male, p = 0.994). The mean age of the institutional cohort was 18.6 ± 5.5 years. Pulmonary metastasis was identified in 1 of 19 institutional patients (5.3%) and in 23 of 411 patients from the literature (5.6%), with no difference between cohorts (p = 1.000). Chest imaging was performed in 42.1% of institutional patients and reported in 47.8% of literature cohorts (p = 0.82). Imaging was performed for routine staging in 87.5% of institutional cases and 63.6% of literature cases (p = 0.338). Among imaged patients at our institution, median tumor size was larger compared with non-imaged patients (3.66 vs 2.20 cm), approaching statistical significance (p = 0.077). The median time from diagnosis to chest imaging was 145 days at our institution. No institutional patients had lung metastasis at initial presentation compared with 3.41% reported in the literature (p = 1.000). All institutional patients were alive and disease-free at last follow-up, and only 3 cases of disease-specific mortality were reported in the literature (0.73%). Conclusions: Although exceedingly rare, lung metastasis in chondroblastoma does occur. Current surveillance practices for chondroblastoma metastasis are inconsistent and lack standardization. Despite metastasis detection, prognosis remains excellent, with only three reported cases in the literature resulting in mortality. These findings suggest that implementing image surveillance may be needed to better define true metastasis rates and guide optimal management strategies.

BACKGROUND:Chondromyxoid fibroma (CMF) is a rare, benign, and locally aggressive bone tumor. It presents diagnostic challenges due to its radiologic similarity to other lesions and variable recurrence rates following surgical treatment. Current literature lacks standardized treatment guidelines, and nonoperative management strategies have not been previously described. METHODS:We conducted a retrospective review of patients diagnosed with CMF at our institution between 2010 and 2024. Eight patients met the inclusion criteria, with treatment modalities including en bloc resection (n=2), intralesional curettage with adjuvants (n=4), and conservative management with serial imaging (n=2). Demographic, clinical, and treatment-related data were collected, and outcomes were analyzed. RESULTS:The cohort consisted of three males and five females, with a mean age of 55.3 ± 11.8 years and an average follow-up of 41.7 ± 28.5 months (range: eight to 104 months). Lesions were located in the distal femur (n=3), pelvis (n=2), clavicle (n=1), great toe (n=1), and T3 vertebral body (n=1). All surgical patients remained free of tumor recurrence, regardless of treatment modality. Two patients (25%) treated with en bloc resection experienced surgical complications requiring revision arthroplasty. Conservative management with serial imaging was successful in two asymptomatic patients (25%), with no evidence of disease progression over eight and 104 months, respectively. CONCLUSION:This case series demonstrates that en bloc resection, intralesional curettage with adjuvants, and conservative management with serial imaging are viable options for managing CMF, depending on patient-specific factors. Notably, to the best of our knowledge, this is the first series to document successful nonoperative management of CMF with serial imaging in carefully selected asymptomatic patients. Our results add to the limited literature on CMF and propose that serial imaging could be a potential management strategy in select patients with CMF.

e23505 Background: Accurate histologic diagnosis is critical for tibial bone tumors, which are among the most common sites for primary bone sarcomas. While percutaneous biopsy (PB) offers minimally invasive sampling, diagnostic accuracy varies by anatomic location. Site-specific data comparing PB to open surgical biopsy (OSB) for tibial lesions is limited. This study compared the diagnostic yield of PB versus OSB for tibial bone lesions and identified factors associated with diagnostic success. Methods: Retrospective cohort study at a tertiary institution, including all tibial bone biopsies from 2015-2025. Primary outcome was diagnostic yield, defined as adequate tissue for definitive histopathologic diagnosis. Diagnostic rates were compared using chi-square tests. Anatomic location, pathologic fracture presence, and technical factors were analyzed for association with diagnostic success. Results: Of 104 tibial biopsies (60 OSB, 44 PB), OSB demonstrated significantly higher diagnostic rate (85% vs 52.3%, p < 0.001). OSB was 1.63 times more likely to yield a diagnosis (95% CI:1.24-2.13) with a number-needed-to-treat of 3.1. Among OSB, diaphyseal lesions had a higher rate of achieving a diagnosis than epiphyseal/metaphyseal (93.9% vs 74.1%, p = 0.032). Pathologic fractures showed a dramatic difference, with OSB achieving 100% diagnostic rate (8/8) versus PB achieving only 20% (1/5, p = 0.013). For PB, mid-diaphyseal (22.2%) and metaphyseal (33.3%) locations had the lowest diagnostic rates. Image guidance modality, needle gauge, and instrument type did not significantly affect outcomes within each biopsy type. Among non-diagnostic cases, 33.3% of OSB and 14.3% of PB ultimately proved malignant. Conclusions: OSB provides significantly superior diagnostic yield compared to PB for tibial lesions, particularly for pathologic fractures and metaphyseal/epiphyseal locations. The substantial difference in diagnostic rates supports preferential use of OSB for tibial bone lesions when feasible, especially given that one-third of non-diagnostic OSB cases ultimately represent malignancy. To our knowledge, this is the first study to examine the impact of tibial anatomic location on biopsy diagnostic yield. Diagnostic outcomes by biopsy method. Outcome OSB (n=60) PB (n=44) p-value Diagnostic rate 85.0% 52.3% <0.001 Relative risk (95% CI) 1.63 (1.24-2.13) - - Repeat biopsy required 16.7% 27.3% 0.287 Pathologic Fracture Diagnostic Rate 100% (8/8) 20% (1/5) 0.013 Diaphysis Diagnostic Rate 93.9% 53.1% <0.001 Epiphysis/Metaphysis Diagnosis Rate 74.1% 50.0% 0.164 OSB = open surgical biopsy; PB = percutaneous biopsy; CI = confidence interval.

e23502 Background: Non-aggressive bone tumors represent approximately 50-60% of surgically treated bone tumors. While osteoid osteomas and chondroblastoma's are well-documented sources of pain, other non-aggressive bone tumors do not have well-defined pain profiles. Understanding the origin of pain in these cases is challenging, particularly when other musculoskeletal conditions are present. This study evaluates the efficacy of corticosteroid injections versus surgical intervention in alleviating pain, aiming to clarify whether pain originates from the bone tumor itself or associated musculoskeletal conditions. Methods: We performed a retrospective review of 37 patients with non-aggressive bone tumor diagnoses located in extremities. Diagnosis was confirmed via core needle/excisional biopsy. Patient demographic, BMI, tumor diagnosis/location, orthopedic comorbidities, pain relief following corticosteroid injections, surgery type, and postoperative surgical pain outcomes were assessed. Results: Diagnoses included enchondroma (15, 40.5%), fibrous dysplasia (8, 21.6%), chondromyxoid fibroma (7, 18.9%), grade 1 chondrosarcoma (6, 16.2%), and non-ossifying fibroma (1, 2.7%). Lesions were located in the femur (8, 21.6%), humerus (8, 21.6%), tibia (6, 16.2%), hand (4, 10.8%), pelvis (4, 10.8%), foot (4, 10.8%), fibula (2, 5.4%), and clavicle (1, 2.7%). All 37 (100.0%) patients reported pain on presentation. Nine (24.3%) patients had a comorbid orthopedic diagnosis in the joint nearest to their bone tumor, 6 (16.2%) of which were osteoarthritis and 3 (8.1%) were tendinitis. Among the 37 patients diagnosed with non-aggressive bone tumors, 7 (19%) received a pretreatment steroid injection, while 30 (81%) did not. Of the 7 patients who received injections, 5 (71%) claimed improved pain relief, while 2 (29%) denied improvements. Four patients who reported initial improvement of pain following steroid injection, reported the pain returned weeks after injection and ultimately underwent surgery with further pain improvement. Among the original 37 patients, 34 (92%) underwent surgery, while 3 (8%) did not. Of the 34 patients who underwent surgery, 31 (91%) reported pain improvement, while 3 (9%) denied any improvement. Conclusions: Corticosteroid injections are not always reliable diagnostic tools in determining the cause of pain in non-aggressive bone lesions. When the pain source remains unclear, surgical intervention resulted in a high rate of pain improvement, suggesting that the primary source of pain is often the tumor itself rather than the associated musculoskeletal condition. This is the first study to specifically address the origin of pain presentation in patients with various non-aggressive bone tumors, presenting a foundation for further investigations into optimal treatment strategies.

OBJECTIVES:To investigate post-operative opioid use, functionality, and overall survival following internal fixation for pathologic or impending fractures at 3 and 6 months. BACKGROUND:Pathologic and impending fractures commonly occur in the proximal femur, and patients may be prescribed opioids prior to surgery and often require opioids for post-operative pain relief. This study compared post-operative opiate usage and ambulatory functional status in patients with impending versus pathologic fractures in the proximal femur. DESIGN:This was a retrospective case-control study of patients using opioids post-operatively who underwent internal fixation for a pathologic or impending fracture between 2016 and 2022. Preoperative and post-operative opioid usage as well as ambulation status and risk factors at 3 and 6 months associated with post-operative opioid use were recorded. RESULTS:Twenty-four pathologic fractures and 23 impending fractures were included. Preoperative opioid daily morphine milligram equivalent was significantly higher in the pathologic fracture group, but there were no significant differences at 3 or 6 months. There was statistically significant post-operative improvement in ambulation status in the combined cohort and impending fracture cohort at 3 months and 6 months. CONCLUSIONS:Although patients did not experience a significant post-operative change in opioid use, patients with pathologic fractures notably required higher opioid dosages preoperatively, and there was overall improvement in function following fixation. Future studies should examine post-operative opioid use with careful consideration of concurrent pain management pain therapies and tumor characteristics.

Desmoid tumor (DT), also known as desmoid fibromatosis, is a rare, locally proliferative tumor characterized by an overgrowth of myofibroblastic cells. Due to the varied clinical presentation of DT, there are a multitude of treatment options. This study provides our institutional experience in characterizing and treating DT as well as patient outcomes. A retrospective review was performed for 49 patients diagnosed with DT. Patient demographics, tumor characteristics, treatment characteristics, and tumor recurrence were reported. We reported our institution's treatment trends over time, relative risk analysis for surgery, as well as univariate analysis for recurrence. Thirty-seven patients received surgery with an overall recurrence rate of 29.7% (11/37). In total, ten patients received medical therapy including tamoxifen/sulindac (n = 7), nirogacestat (n = 1), and sorafenib (n = 2). One patient has been followed with active surveillance. Relative risk for surgery and tumor recurrence was not significantly correlated with race, gender, location, or large tumor size > 5 cm. Four patients treated with medical therapy experienced tumor reduction and symptomatic improvement. Management of DT includes many surgical and non-surgical options. We noted a similar recurrence rate in patients who received surgical treatment to what has been reported in the literature roughly 33%. We also noted effective tumor control in patients receiving medical therapy. As such, surgery can be utilized in situations with well-demarcated DT which can be removed en bloc, while utilizing medical therapy for highly invasive tumors.

BACKGROUND:Chondrosarcoma accounts for 20% of all bone sarcomas and may present with soft tissue extension. The presence of an extraosseous component, along with positive surgical margins, independently have been associated with increased risk of local recurrence and decreased survival. The purpose of this investigation is to describe the treatment and outcomes of six chondrosarcoma patients who presented with chondrosarcoma with soft tissue extension along with positive surgical margins post negative en bloc resection. CASE:This was a retrospective review over a consecutive 13-year period. Data including treatment details and outcomes were included. All patients underwent attempted negative margin en bloc resection and encountered unplanned positive margins on intraoperative determination or postoperative pathology (R1). A total of six cases were identified. Average age (SD) was 61.8 years (6.11) with median (IQR) follow-up of 17.0 months (10.3-39.5). Three (50.0%) cases arose in the extremities, and 3 (50.0%) cases in the pelvis. All patients underwent attempted negative margin en bloc resection. Three (50.0%) cases recurred with median (IQR) time to recurrence of 10.0 months (9.0-31.0). At study conclusion, 5 (83.3%) were alive with median (IQR) survival of 20.5 months (11.3-41.0). CONCLUSION:Despite limited sample size, our data reflected a significantly higher recurrence rate compared to either chondrosarcomas with positive margins or extraosseous extension. Our cohort represents a high-risk subgroup of chondrosarcoma patients, which may dictate increased monitoring and guide future treatment recommendations for these patients.

e13503 Background: Soft tissue sarcomas (STS) are a rare malignancy, approximately 13,590 new cases are diagnosed annually in the United States. Due to their management complexity, the National Comprehensive Cancer Network (NCCN) has developed evidence-based guidelines to standardize the workup and treatment of STS, aiming to ensure a high quality of care. Despite the established benefits of guideline adherence, factors influencing compliance remain underexplored. This study aims to assess adherence to NCCN guidelines for STS at a single academic institution throughout the year 2023. By evaluating compliance rates and patient proximity to the cancer center, we seek to gain a deeper understanding of the challenges in delivering guideline-concordant care. Methods: Following Institutional Review Board approval, a natural language search was used to identify patients diagnosed with or treated for soft tissue sarcomas (STS) at a single academic institution in 2023. Ninety-one patients were identified. Individuals were included if they received a diagnosis or underwent the majority of their workup or treatment during this period. We then reviewed each patient's workup and treatment plan to evaluate adherence to the NCCN guidelines. This included a proper history & physical, primary site imaging, CNB, chest/abdominal imaging, presentation to our multidisciplinary team, wide margin surgical resection, radiation therapy, and chemotherapy. Estimated travel time was calculated using Google Maps in drive mode. The end point for all calculations was our central downtown academic cancer center, with the starting point being the patient’s home address. Results: A total of 43 patients were included in the study. The most common diagnoses were spindle cell sarcoma and undifferentiated pleomorphic sarcoma (22.73% each). The most common TNM stage was IV (51.16%). All patients (100%) met workup compliance according to the NCCN guidelines. Thirty-four patients (79.07%) completed their treatment course adhering to the NCCN guidelines, while 9 patients (20.93%) fell short. Four (9.30%) passed away while receiving treatment, 3 (6.98%) were recommended for further treatment but declined, and 2 (4.65%) were seen as second opinions and returned to their original provider for treatment. The three cases where further treatment was declined traveled distances of 1.5 miles (8 minutes), 10.9 miles (35 minutes), and 22.5 miles (55 minutes). Travel distance ranged from 1.5 to 201 miles, with a median distance and travel time of 31 miles and 55 minutes. Conclusions: This study demonstrates a high level of compliance with NCCN guidelines for extremity STS at a single academic institution. Distance to the central academic cancer center did not appear to be a significant factor in adherence. Future studies should explore additional variables to better understand the full scope of influences on guideline adherence in sarcoma care.

Background Soft tissue sarcomas (STS) are rare and complex malignancies. Due to their infrequency and complexity, the National Comprehensive Cancer Network (NCCN) provides evidence-based guidelines to guide the workup and treatment of STS. Adherence to these guidelines is crucial, as demonstrated by studies showing improved survival outcomes with compliance. However, factors influencing adherence, such as proximity to treatment centers, remain underexplored. This study aims to assess adherence to the NCCN guidelines at a single academic institution in 2023 and identify factors that affect compliance. Materials and methods We performed a retrospective review of patients diagnosed with or treated for STS at a single academic institution in 2023. In accordance with NCCN guidelines and based on tumor staging, we reviewed whether patients received the proper workup and treatment, including a history and physical examination, primary site imaging, core needle biopsy, chest/abdominal imaging, presentation to a multidisciplinary team, wide resection surgery, radiation therapy, and chemotherapy. Results A total of 43 patients were included in the study. The most common diagnoses were spindle cell sarcoma and undifferentiated pleomorphic sarcoma, each occurring in 10 patients (22.73% each). The most common TNM stage was IV in 22 patients (51.16%). All 43 patients (100%) met workup compliance according to the NCCN guidelines. Thirty-four patients (79.07%) completed their treatment course, adhering to the NCCN guidelines throughout. Two (4.65%) underwent a complete workup but were seen as second opinions and returned to their previous provider to complete their care. Three (6.98%) were recommended for further treatment of either radiation therapy or chemotherapy but declined. These cases had travel distances of 1.5, 10.9, and 22.5 miles, respectively. Four (9.30%) passed away while undergoing treatment. Travel distance ranged from 1.5 to 201 miles, with a median distance of 31 miles and a median travel time of 55 minutes. Conclusions Our findings demonstrate a high rate of compliance with NCCN guidelines at a single academic institution. Contrary to expectations, proximity to the cancer center did not significantly affect adherence. Further studies are needed to explore additional factors influencing non-compliance, such as socioeconomic and healthcare system barriers.

BACKGROUND AND OBJECTIVES:Undifferentiated pleomorphic sarcoma (UPS) is a frequent subtype within the heterogeneous group of soft tissue sarcomas (STS). The use of radiotherapy (RT) has become an important component of a multimodal approach to treating STS. Key studies have demonstrated that the addition of RT improves rates of local control in STS, though the effect on overall survival (OS) is less clear. Furthermore, there is very limited and conflicting evidence regarding effect of RT on overall survival in UPS. The purposes of this investigation were to examine the association between RT and OS in UPS patients undergoing surgical resection and to determine independent prognostic indicators of OS in this patient population. METHODS:This was a retrospective review of patients who underwent surgical treatment for primary UPS from 1993 to 2021. Associations between RT and OS were analyzed with Kaplan-Meier curves and log-rank testing. Cox proportional hazards regression analysis was used to determine independent prognostic factors of OS. RESULTS:One hundred and fourteen patients who underwent surgical resection of primary UPS were included in the study. Ninety-six (84.2 %) patients received RT perioperatively. Use of RT was associated with improved OS on log-rank testing (hazard ratio (HR) 0.20; 95 % confidence interval (CI) 0.11-0.36; p < 0.001). On multivariate analysis, RT was an independent predictor of improved OS (HR 0.18; 95 % CI 0.09-0.39; p < 0.001) while metastasis at presentation (HR 4.82; 95 % CI 2.26-10.27; p < 0.001) and older age (HR 1.92; 95 % CI 1.20-3.36; p = 0.02) were predictive of decreased OS. Use of RT was not significantly associated with a lower rate of local recurrence in our cohort (p = 0.49). CONCLUSIONS:Use of RT in combination with surgery was an independent prognostic indicator of improved overall survival in UPS patients. Older age and metastasis at presentation were associated with worse overall survival. Based on this and other available studies, treatment for UPS should involve limb-sparing resection when feasible with RT to ensure optimal survival.

IntroductionAtypical lipomatous tumor (ALT) in the extremities is a locally aggressive adipocytic tumor with the potential risk of transformation into dedifferentiated liposarcoma (DDLS). Studies seldom differentiate whether DDLS was diagnosed on initial biopsy, final resected specimen, or subsequent recurrence. Our study seeks to characterize how and when patients received their ALT or DDLS diagnoses to better understand the relationship between the two neoplasms.MethodsWe performed a retrospective review of patients diagnosed with ALT or DDLS of the extremities. Clinical characteristics, including the method of diagnosis of an ALT or DDLS, time between diagnoses, and tumor recurrence was recorded. Univariate/multivariate analysis was performed to identify risk factors.ResultsForty-five patients were diagnosed with ALT after core needle biopsy (CNB) and 41 of them received marginal en bloc excision. Three (7.3%) of these patients had a heterogeneous tumor on final resection, pathology revealed both ALT and DDLS. Four patients (8.2%) were diagnosed with DDLS from CNB and received negative margin en bloc excision. One of these tumors was identified as heterogeneous ALT/DDLS after resection. Fifty-three patients received marginal en bloc resection without CNB after a benign lipomatous mass was suspected on CT/MRI. Among these, one (1.9%) had a tumor with a heterogeneous composition of both ALT and DDLS on pathology. There were 11 (11.7%) ALT recurrences and 1 (1.0%) DDLS recurrence after ALT resection.ConclusionObtaining a proper diagnosis whether ALT or DDLS is critical. Our cohort found that amongst those concerning lipomatous lesions biopsied, 7.84% will show biopsy proven DDLS. Additionally, 6.67% of the biopsies will be false negatives and show DDLS on final pathology. Furthermore, our local recurrence for ALT was 11.7% recurring as ALT and 1.0% recurring as DDLS.

Background and Objectives: Wide margin resection for pelvic tumors via internal hemipelvectomy is among the most technically challenging procedures in orthopedic oncology. As such, surgeon experience and technique invariably affect patient outcomes. The aim of this clinical study was to assess how an individual surgeon's experiences and advancements in technology and techniques in the treatment of internal hemipelvectomy have impacted patient outcomes at our institution. Methods: This study retrospectively examined a single tertiary academic institution's consecutive longitudinal experience with internal hemipelvectomy for primary sarcoma or pelvic metastases over a 26-year period between the years 1994 and 2020. Outcomes were assessed using two separate techniques. The first stratified patients into cohorts based on the date of surgery with three distinct "eras" ("early," "middle," and "modern"), which reflect the implementation of new techniques, including three-dimensional (3D) computer navigation and cutting guide technology into our clinical practice. The second method of cohort selection grouped patients based on each surgeon's case experience with internal hemipelvectomy ("inexperienced," "developing," and "experienced"). Primary endpoints included margin status, complication profiles, and long-term oncologic outcomes. Whole group multivariate analysis was used to evaluate variables predicting blood loss, operative time, tumor-free survival, and mortality. Results: A total of 72 patients who underwent internal hemipelvectomy were identified. Of these patients, 24 had surgery between 1994 and 2007 (early), 28 between 2007 and 2015 (middle), and 20 between 2016 and 2020 (modern). Twenty-eight patients had surgery while the surgeon was still inexperienced, 24 while developing, and 20 when experienced. Evaluation by era demonstrated that a greater proportion of patients were indicated for surgery for oligometastatic disease in the modern era (0% vs. 14.3% vs. 35%, p = 0.022). Fewer modern cases utilized freehand resection (100% vs. 75% vs. 55%, p = 0.012), while instead opting for more frequent utilization of computer navigation (0% vs. 25% vs. 20%, p = 0.012), and customized 3D-printed cutting guides (0% vs. 0% vs. 25%, p = 0.002). Similarly, there was a decline in the rate of massive blood loss observed (72.2% vs. 30.8% vs. 35%, p = 0.016), and interdisciplinary collaboration with a general surgeon for pelvic dissection became more common (4.2% vs. 32.1% vs. 85%, p < 0.001). Local recurrence was less prevalent in patients treated in middle and modern eras (50% vs. 15.4% vs. 25%, p = 0.045). When stratifying by case experience, surgeries performed by experienced surgeons were less frequently complicated by massive blood loss (66.7% vs. 40% vs. 20%, p = 0.007) and more often involved a general surgeon for pelvic dissection (17.9% vs. 37.5% vs. 65%, p = 0.004). Whole group multivariate analysis demonstrated that the use of patient-specific instrumentation (PSI) predicted lower intraoperative blood loss (p = 0.040). However, surgeon experience had no significant effect on operative time (p = 0.125), tumor-free survival (p = 0.501), or overall patient survival (p = 0.735). Conclusion: While our institution continues to utilize neoadjuvant and adjuvant therapies following current guideline-based care, we have noticed changing trends from early to modern periods. With the advent of new technologies, we have seen a decline in freehand resections for hemipelvectomy procedures, and a transition to utilizing more 3D navigation and customized 3D cutting guides. Furthermore, we have employed the use of an interdisciplinary team approach more regularly for these complicated cases. Although our results do not demonstrate a significant change in perioperative outcomes over the years, our institution's willingness to treat more complex cases likely obscures the benefits of surgeon experience and recent technological advances for patient outcomes.

Management of patients with bony sarcoma requires a multidisciplinary approach that optimizes oncologic and functional outcomes. With the advent of new orthopedic and plastic surgery techniques, limb salvage is becoming a more common treatment for bony sarcomas. Bony reconstruction has evolved to include allograft, alloplastic, autograft, and combined approaches. Soft tissue options for coverage and functional reconstruction have also expanded. When amputation is indicated, function and pain outcomes can be optimized. Limb-sparing resection for bony sarcoma is an excellent option for most patients, thanks to advancements in oncologic and surgical treatment options. With preservation or reconstruction of vital soft tissues, reconstruction of bone defects often can be addressed with a prosthetic implant, allograft, autograft, or combination of techniques.

Background:Proximal femoral replacement (PFR) is a reconstruction technique after tumor resection or for revision of failed total hip arthroplasty (THA). However, despite acceptable long-term oncologic and functional outcomes, extensive soft tissue or bone loss increases the risk for prosthetic instability. Instability may depend on the construct chosen for reconstruction, with current options including bipolar, constrained, or dual mobility implants. Clinical studies comparing patient outcomes after PFR with these three different constructs are limited. Methods:This study retrospectively examined a single tertiary academic institution's experience with PFR over a fifteen-year period. The medical records of patients who underwent PFR for indications such as tumor and failed THA with bone loss were reviewed. Patients were stratified into cohorts based on use of bipolar, constrained, or dual mobility implants. Patient demographics, disease characteristics, perioperative data, and data on prosthetic dislocations were recorded. ANOVA and chi-square testing was performed for continuous and categorical variables, respectively. The threshold for statistical significance was set to p < 0.05. Results:106 patients were identified who underwent PFR. 46 underwent PFR with bipolar prosthesis (follow-up: 20 ± 24.57 months), 42 with constrained liner (follow-up: 30.45 ± 35.32 months), and 18 with dual mobility (follow-up: 15.38 ± 15.67 months). Only BMI (p = 0.036) and smoking history (P = 0.002) differed between groups. Dislocations occurred in 4 (8.7 %) patients who underwent reconstruction with bipolar prosthesis, compared to 8 (19.0 %) with constrained liner, and 3 (16.7 %) patients with dual mobility. Mean time to dislocation was significantly longer in dual mobility patients (P = 0.009). There were no differences in instances of early dislocation between groups (P = 00.238). Conclusion:While study numbers are low, mean time to dislocation was significantly longer with dual mobility. Additional large-scale longitudinal studies are needed to fully elucidate the differences in outcomes amongst these three treatments.

CASE:A 40-year-old man was evaluated for a painful mass on his right calf, and a 36-year-old woman presented with a painless mass on her right foot. Final pathology revealed marked nuclear atypia and positivity for S100/SOX10 and AE1/AE3 confirming diagnoses of myoepithelial carcinoma. Both patients underwent surgical resection and are without evidence of local recurrence or metastatic disease at 1-year follow-up. CONCLUSION:Soft-tissue tumors presenting in the extremities warrant careful evaluation and timely histopathologic diagnosis. Myoepithelial carcinomas are rare, aggressive tumors with a propensity for local recurrence and metastasis. Treatment of these tumors should be discussed by a multidisciplinary tumor team.

e24061 Background: Pathologic and impending fractures commonly occur in the proximal femur, and patients may be prescribed opioids prior to surgery and often require opioids for postoperative pain relief. This study compared postoperative opiate usage and ambulatory functional status in patients with impending versus pathologic fractures in the proximal femur. Methods: This was a retrospective review of patients using opioids postoperatively who underwent internal fixation for a pathologic or impending fracture between 2016 and 2022. Preoperative and postoperative opioid usage as well as ambulation status and risk factors at three and six months associated with postoperative opioid use were recorded. Results: Twenty-four pathologic fractures and twenty-three impending fractures were included. Preoperative opioid daily morphine milligram equivalent (MME) was significantly higher in the pathologic fracture group (p = 0.021), but there were no significant differences at three or six months. In the impending fracture group, daily MME at three months was significantly higher than preoperative daily MME (p = 0.018) but returned to preoperative levels at six months. There was statistically significant improvement in ambulation status in the combined cohort (p = 0.008) and impending fracture cohort (p = 0.016) at 6 months. Conclusions: Although patients did not experience a significant postoperative change in opioid use, patients with pathologic fractures notably required higher opioid dosages and there was overall improvement in function following fixation. Future studies should examine postoperative opioid use with careful consideration of concurrent pain management pain therapies and tumor characteristics.[Table: see text]

Myxoid/round cell liposarcomas (MRCLPS) are a rare soft tissue sarcoma. We report the largest sarcoma in our institutional history. We discuss the patient’s surgical management and treatment of the tumor and challenges given its dimensions. Several complications arose following primary resection that were managed by a multidisciplinary team. Although MRCLPS can vary in size, large MRCLPS must be treated cautiously given the potential for complications. Additionally, multidisciplinary treatment of MRCLPS is essential in diagnosing and treating these complex cases.

PURPOSE:Machine learning (ML) models have been used to predict cancer survival in several sarcoma subtypes. However, none have investigated extremity leiomyosarcoma (LMS). ML is a powerful tool that has the potential to better prognosticate extremity LMS. METHODS:The Surveillance, Epidemiology, and End Results (SEER) database was queried for cases of histologic extremity LMS (n = 634). Patient, tumor, and treatment characteristics were recorded, and ML models were developed to predict 1-, 3-, and 5-year survival. The best performing ML model was externally validated using an institutional cohort of extremity LMS patients (n = 46). RESULTS:All ML models performed best at the 1-year time point and worst at the 5-year time point. On internal validation within the SEER cohort, the best models had c-statistics of 0.75-0.76 at the 5-year time point. The Random Forest (RF) model was the best performing model and used for external validation. This model also performed best at 1-year and worst at 5-year on external validation with c-statistics of 0.90 and 0.87, respectively. The RF model was well calibrated on external validation. This model has been made publicly available at https://rachar.shinyapps.io/lms_app/ CONCLUSIONS: ML models had excellent performance for survival prediction of extremity LMS. Future studies incorporating a larger institutional cohort may be needed to further validate the ML model for LMS prognostication.

Background and objectives Internal hemipelvectomy is a limb sparing procedure most commonly indicated for malignant bone and soft tissue tumors of the pelvis. Partial resection and pelvic reconstruction may be challenging for orthopedic oncologists due to late presentation, high tumor burden, and complex anatomy. Specifically, wide resection of tumors involving the periacetabular and sacroiliac (SI) regions may compromise adjacent vital neurovascular structures, impair wound healing, or limit functional recovery. We aimed to present a series of patients treated at our institution who underwent periacetabular internal hemipelvectomy (Type II) with or without sacral extension (Type IV) in combination with a systematic review to investigate postoperative complications, functional outcomes, and implant and patient survival following pelvic tumor resection via Type II hemipelvectomy with or without Type IV resection. Materials and methods A surgical registry of consecutive patients treated with internal hemipelvectomy for primary or secondary pelvic bone tumors at our institution since 1994 was retrospectively reviewed. All type II resection patients were stratified into two separate cohorts, based on whether or not periacetabular resection was extended beyond the SI joint to include the sacrum (Type IV), as per the Enneking and Dunham classification. Patient demographics, operative parameters, complications, and oncological outcomes were collected. Categorical and continuous variables were compared with Pearson's chi square or Fisher's exact test and the Mann-Whitney U test, respectively. Literature review according to PRISMA guidelines queried studies pertaining to patient outcomes following periacetabular internal hemipelvectomy. The search strategy included combinations of the key words “internal hemipelvectomy”, “pelvic reconstruction”, “pelvic tumor”, and “limb salvage”. Pooled data was compared using Pearson's chi square. Statistical significance was established as p < 0.05. Results A total of 76 patients were treated at our institution with internal hemipelvectomy for pelvic tumor resection, of whom 21 had periacetabular resection. Fifteen patients underwent Type II resection without Type IV involvement, whereas six patients had combined Type II/IV resection. There were no significant differences between groups in operative time, blood loss, complications, local recurrence, postoperative metastasis, or disease mortality. Systematic review yielded 69 studies comprising 929 patients who underwent internal hemipelvectomy with acetabular resection. Of these, 906 (97.5 %) had only Type II resection while 23 (2.5 %) had concomitant Type II/IV resection. While overall complication rates were comparable, Type II resection alone produced significantly fewer neurological complications when compared to Type II resection with sacral extension (3.9 % vs. 17.4 %, p = 0.001). No significant differences were found between rates of wound complications, infections, or construct failures. Local recurrence, postoperative metastasis, and survival outcomes were similar. Type II internal hemipelvectomy without Type IV resection on average produced higher postoperative MSTS functional scores than with Type IV resection. Conclusion In our series, the two groups exhibited no differences. From the systematic review, operative parameters, local recurrence or systemic metastasis, implant survival, and disease mortality were comparable in patients undergoing Type II internal hemipelvectomy alone compared to patients undergoing some combination of Type II/IV resection. However, compound resections increased the risk of neurological complications and experienced poorer MSTS functional scores.

Background and Objectives: The optimal timing between preoperative embolization of hypervascular metastatic bone lesions and surgery has yet to be established. Our analysis sought to evaluate embolization timing impacts blood loss, transfusion risk, and operative time in patients with hypervascular primary tumors. Methods: We identified patients with renal cell (RCC) or thyroid carcinoma under going surgery between 1992 and 2023. Patients were segregated into the following cohorts: (1) no embolization preoperatively, (2) surgery <24 h of embolization, and (3) surgery >24 h after embolization. Multivariate logistic regression analyses were performed to assess the effect of embolization timing while controlling for confounding variables. Results: No differences were seen in all evaluated outcomes between immediate and delayed embolization cohorts. No differences in estimated blood loss were seen between the immediate (OR: 0.685, 95% CI: 0.159-2.949;p= 0.611) and delayed (OR: 0.568, 95%CI: 0.093-3.462;p= 0.539) surgery cohorts compared with patients without embolization. Surgery >24 h after embolization was not associated with a higher risk of prolonged operative time (OR: 13.499, 95% CI: 0.832-219.146;p= 0.067).Conclusions: These findings suggest that surgery may be safely delayed beyond 24 h from embolization without a higher risk of bleeding. In appropriately selected cohorts, embolization may not be needed preoperatively.