Calcium phosphate cement and locked plate augmentation of distal femoral defects: A biomechanical analysis.

PURPOSE: Bone tumors are common in the distal femur and often treated with intralesional curettage. The optimal method of stabilization of large distal femoral defects after curettage remains unclear. The goal of this study is to compare stabilization techniques for large distal femoral defects. METHODS: Large defects (60 cm3) were milled in the distal lateral metaphysis of 45 adult composite sawbone femurs. The defect was either (1) left untreated or reconstructed with (2) locked plate fixation, (3) calcium phosphate cement packing, or (4) locked plate fixation with calcium phosphate cement packing, or (5) polymethylmethacrylate packing. Each specimen then underwent axial and torsional stiffness testing followed by torsional loading to failure. The data were analyzed using ANOVA with Tukey-Kramer post-hoc analysis. RESULTS: The calcium phosphate cement filled defect with a locked plate was the stiffest construct in axial and torsional loading as well as the strongest in torque to failure. However, this difference only reached significance with respect to all other groups in torque to failure testing. The calcium phosphate cement filled defect with a locked plate was significantly stiffer than three of the four other groups in both axial and torsional stiffness testing. CONCLUSIONS: These results indicate that calcium phosphate cement, with or without the addition of locked plate fixation, may provide improved construct stability under time zero testing conditions. This result warrants further testing under cyclic loading condition and consideration for fixation of large femoral metaphyseal defects in future clincal trails.

Giant cell tumor of bone.

EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Identify at-risk populations for giant cell tumor of bone. 2. Recognize the biology that drives giant cell tumor of bone. 3. Describe modern surgical and adjuvant techniques to effectively treat giant cell tumor of bone. 4. Recognize the complications associated with radiation therapy, poor resection, and adjuvant treatments. Giant cell tumor of bone (GCT) is a benign, locally aggressive bone tumor. Giant cell tumor of bone primarily affects the young adult patient population. The natural history of GCT is progressive bone destruction leading to joint deformity and disability. Surgery is the primary mode of treatment, but GCT has a tendency to recur locally despite a range of adjuvant surgical options. Pulmonary metastasis has been described. However, systemic spread of GCT rarely becomes progressive, leading to death. This review presents the clinicopathologic features of GCT and a historical perspective that highlights the current rationale and controversies regarding the treatment of GCT.

Torsional properties of distal femoral cortical defects.

The optimal management of pathologic long bone lesions remains a challenge in orthopedic surgery. The goal of the current study was to investigate the effect of defect depth on the torsional properties of the distal femur. A laterally placed distal metaphyseal cylindrical defect was milled in the cortex of the distal femur in 20 composite models. The proximal extent of the defects was constant. By decreasing the radius of the cylinder that intersected this predefined cord, 4 different radii defining 4 different depths of resection of the distal femur were created for testing: 17%, 33%, 50%, and 67% cortical defects, when normalized to the width of the femur at the level of resection. Each femur was mounted into a hydraulic axial/torsion materials testing machine and each specimen underwent torsional stiffness testing and torsional failure in external rotation. The specimens with less than a 33% cortical loss consistently demonstrated a superiorly oriented spiral fracture pattern, while the specimens with greater than a 50% cortical loss consistently demonstrated an inferiorly oriented transverse fracture pattern. The cortical defects were all statistically (P<.05) less stiff in torsion as the defect grew larger. There was a strong linear correlation between the mean torsional stiffness and cortical defect size (r(2)=0.977). This observation is supported by finite element analysis. The amount of femur remaining is crucial to stability. This biomechanical analysis predicts a critical loss of torsional integrity when a cortical defect approaches 50% of the width of the femur.

Phase I trial of neoadjuvant conformal radiotherapy plus sorafenib for patients with locally advanced soft tissue sarcoma of the extremity.

BACKGROUND: Despite effective local therapy with surgery and radiotherapy (RT), ~50 % of patients with high-grade soft tissue sarcoma (STS) will relapse and die of disease. Since experimental data suggest a significant synergistic effect when antiangiogenic targeted therapies such as sorafenib are combined with RT, we chose to evaluate preoperative combined modality sorafenib and conformal RT in a phase I/II trial among patients with extremity STS amenable to treatment with curative intent. METHODS: For the phase I trial, eight patients with intermediate- or high-grade STS >5 cm in maximal dimension or low-grade STS >8 cm in maximal dimension received concomitant sorafenib (dose escalation cohort 1:200 twice daily, cohort 2:200/400 daily) and preoperative RT (50 Gy in 25 fractions). Sorafenib was continued during the entire period of RT as tolerated. Surgical resection was completed 4-6 weeks following completion of neoadjuvant sorafenib/RT. Three sorafenib dose levels were planned. Primary endpoints of the phase I trial were maximal tolerated dose and dose-limiting toxicity (DLT). RESULTS: Eight patients were enrolled in the phase I (five females, median age 44 years, two high-grade pleomorphic, two myxoid/round cell liposarcoma, four other). Median tumor size was 16 cm (range 8-29), and all tumors were located in the lower extremity. Two of five patients treated at dose level 2 developed DLT consisting of grade 3 rash not tolerating drug reintroduction. Other grade 3 side effects included anemia, perirectal abscess, and supraventricular tachycardia. Radiation toxicity (grade 1 or 2 dermatitis; N = 8) and post-surgical complications (three grade 3 wound complications) were comparable to historical controls and other series of preoperative RT monotherapy. Complete pathologic reponse (≥95 % tumor necrosis) was observed in three patients (38 %). CONCLUSION: Neoadjuvant sorafenib in combination with RT is tolerable and appears to demonstrate activity in locally advanced extremity STS. Further study to determine efficacy at dose level 1 is warranted. (ClinicalTrials.gov identifier NCT00805727).

Influence of physician specialty on treatment recommendations in the multidisciplinary management of soft tissue sarcoma of the extremities.

IMPORTANCE: Although prospective randomized data are available to guide the multidisciplinary management of soft tissue sarcoma (STS) of the extremities, controversy exists regarding adjuvant chemotherapy and radiation therapy. OBJECTIVE: To determine if clinical specialty introduces bias in recommendations for multimodality treatment of STS. DESIGN: Electronic survey. SETTING: Database of active members of the American Society of Clinical Oncology, the Society of Surgical Oncology, and the Connective Tissue Oncology Society. PARTICIPANTS: Members of specialty oncology societies with an active interest in STS. EXPOSURE: Physician specialty. MAIN OUTCOMES AND MEASURES: Survey responses regarding the multidisciplinary management of STS were scored on a 5-point Likert scale and analyzed using analysis of variance. RESULTS: The questionnaire was completed by 320 of 490 potential respondents (65%), including medical (18%), radiation (8%), orthopedic (22%), and surgical oncologists (45%). Respondents concurred on the use of radiation therapy for margins positive for tumor, for high-grade tumors, for improvement in local control, for tumors larger than 10 cm, and for tumors in close proximity to a neurovascular bundle. Respondents diverged on the use of radiation therapy for tumors 5 to 10 cm in size, for low-grade tumors, for radiation-associated STS, and for survival benefit. Only radiation oncologists felt that radiation therapy was underutilized as a treatment modality (mean [SEM] Likert scale score, 2.44 [0.12]; P < .001). There was agreement on the use of chemotherapy for synovial sarcoma, for high-grade tumors, for tumors larger than 10 cm, for patients younger than 50 years of age, and for survival benefit. Medical oncologists were more likely to recommend chemotherapy for margins positive for tumor (mean [SEM] score, 3.12 [0.12]; P = .03) and for improvement in local control (mean [SEM] score, 2.91 [0.12] P = .08). Surgical oncologists placed the least emphasis on chemotherapy in the overall treatment plan (mean [SEM] score, 2.60 [0.07]; P = .001). CONCLUSIONS AND RELEVANCE: Specialty bias exists in adjuvant treatment recommendations for STS. This highlights the importance of multidisciplinary STS tumor boards and interdisciplinary care to facilitate consensus decision making for individual patients.

Complete pathologic response to neoadjuvant radiotherapy is predictive of oncological outcome in patients with soft tissue sarcoma.

UNLABELLED: We sought to determine if complete pathological necrosis (pathCR) predicts favorable oncological outcome in soft tissue sarcoma (STS) patients receiving pre-operative radiation monotherapy (RT). PATIENTS AND METHODS: We evaluated 30 patients with primary STS treated with neoadjuvant RT followed by definitive resection, from 2000 to 2010 at our institution. We defined ≥ 95% tumor necrosis as pathCR. RESULTS: There were 22 STS of the extremities (73%), 7 of the retroperitoneum (23%), and 1 (4%) of the trunk. The median pathological percentage of tumor necrosis was 35% (range 5-100%) with three tumors (10%) demonstrating pathCR. With a median follow-up of 40 months, the 5-year local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS), and overall survival (OS) for the entire cohort were 100%, 61% ± 11%, and 69% ± 11%, respectively. Among patients with pathCR, 3-year DRFS was 100% compared to 63±11% in patients without pathCR (p=0.28). CONCLUSION: Following neoadjuvant RT for STS, pathCR is associated with a clinically but not statistically significant 37% improvement in 3-year DRFS.

P16 expression predicts necrotic response among patients with osteosarcoma receiving neoadjuvant chemotherapy.

Although pathologic response to neoadjuvant chemotherapy is highly correlated with survival among patients with osteosarcoma, there are currently no established molecular markers to predict response to chemotherapy. The objective of this study was to investigate the relationship of P16 expression in pretreatment osteosarcoma tumors to pathologic necrotic response after neoadjuvant chemotherapy. A tissue microarray was created from paraffin-embedded pretreatment biopsy specimens of 40 patients with osteosarcoma. Immunohistochemistry was performed with commercially available P16 monoclonal mouse antibody. Expression of P16 was defined as nuclear staining in 30% or greater of cells. Percent tumor necrosis was measured in postchemotherapy resection specimens per established protocols, and 90% or greater tumor necrosis was considered "good." Data were abstracted on age, sex, tumor site, and histologic subtype. Univariate and multivariate analyses were performed. The median age was 15 years, 52% were female, and 35% of tumors were located in the femur. P16 expression was present in 62%. Median posttreatment tumor necrosis was 90%, and 55% of patients experienced "good" chemotherapy response (≥90% necrosis). On univariate analysis, P16 expression correlated positively with median percent necrosis and "good" chemotherapy response (P=.004 and .003, respectively). On logistic regression analysis, P16 expression was independently associated with chemotherapy response after controlling for age, subtype, sex, and location (odds ratio, 43.5; 95% confidence interval, 2.64-708.9; P=.008). In summary, immunohistochemical expression of P16 significantly correlates with chemotherapy response in osteosarcoma. P16 expression may be a useful biomarker to guide treatment selection.

Predicting survival for well-differentiated liposarcoma: the importance of tumor location.

BACKGROUND: Although well-differentiated liposarcoma (WD Lipo) is a low grade neoplasm with a negligible risk of metastatic disease, it can be locally aggressive. We hypothesized that survival for WD Lipo varies significantly based on tumor location. METHODS: We identified 1266 patients with WD Lipo in the Surveillance, Epidemiology, and End Results database from 1988-2004. After excluding patients diagnosed by autopsy only, those lacking histologic confirmation, those lacking data on tumor location, and those with metastatic disease or unknown staging information, we arrived at a final study cohort of 1130 patients. Clinical, pathologic, and treatment variables were analyzed for their association with overall survival (OS) and disease-specific survival (DSS) using Kaplan-Meier analysis and Cox proportional hazards multivariate models. RESULTS: Mean age was 61 y (± 14.6), 72.2% were white, and 60.4% were male. Eighty-one percent of patients were treated with surgical therapy alone, 4.6% were treated with radiotherapy (RT) alone, and 12.9% were treated with both surgery and RT. Extremity location was most common (41.6%), followed by trunk (29%), retroperitoneal/intra-abdominal (RIA, 21.6%), thorax (4.2%), and head/neck (3.6%). With a median follow-up of 45 mo, median OS was 115 mo (95% confidence interval [CI] 92-138 mo) for RIA tumors compared to not reached for other tumor locations (P = 0.002). On multivariate analysis, increasing age and RIA location both predicted worse OS and DSS while tumor size, race, sex, receipt of RT, and Surveillance, Epidemiology, and End Results (SEER) stage did not. Tumor size became a significant predictor of worse DSS, but not OS, only when site, SEER stage, and extent of resection were removed from the multivariate model. Non-RIA locations, including extremity, experienced statistically similar OS, but 5-y DSS for trunk location was intermediate [92.3%, (95% CI 88.5%-96.1%) compared with 98.0% (95% CI, 96.2%-99.8%) for extremity and 86.6 (95% CI 81.1%-92.1%) for RIA, P < 0.001]. CONCLUSIONS: Among patients with WD Lipo, RIA location is associated with significantly worse outcomes independent of tumor size. Future studies should focus on the anatomic and biologic reasons for these differences.

Histologic type predicts survival in patients with retroperitoneal soft tissue sarcoma.

BACKGROUND: Histologic grade, completeness of resection, and presence of metastases are traditionally regarded as the primary factors in predicting survival for retroperitoneal soft tissue sarcoma (RPSTS). We sought to examine the importance of histologic type as a prognostic factor among patients with RPSTS. METHODS: We identified 2337 cases of RPSTS in the Surveillance, Epidemiology, and End Results (SEER) database from 1988 to 2004. After excluding 273 cases of age <18, identification by autopsy only, or absence of histologic confirmation, we arrived at a final study cohort of 2064 patients. Overall survival (OS) and disease-specific survival (DSS) were estimated using the Kaplan-Meier method. Multivariate analysis was performed using a Cox proportional hazards model, adjusting for age, gender, race, histologic type, histologic grade, tumor size, extent of resection, and SEER summary stage. RESULTS: Among 33 histologic types, leiomyosarcoma (28.7%), well-differentiated/dedifferentiated liposarcoma (20.3%), liposarcoma not otherwise specified (NOS) (11.9%), malignant fibrous histiocytoma (MFH-11.0%), and sarcoma NOS (10.7%) were the most prevalent. Grade distribution was low, 24.2%; intermediate, 16%; high 34.3%, and unknown, 25.5%. Surgery was performed in 85.8%, and radiotherapy was administered to 22.8%. With a median follow-up of 38 mo, median OS was 78, 35, 25, 18, and 10 mo for liposarcoma, leiomyosarcoma, other histologies, MFH, and sarcoma NOS, respectively (P < 0.0001). Median DSS was 120, 53, not reached, 30, and 13 mo for liposarcoma, leiomyosarcoma, other histologies, MFH, and sarcoma NOS, respectively (P < 0.0001). On multivariate analysis, histologic type was associated with statistically significant differences in both OS and DSS. CONCLUSIONS: Histologic type is an important predictor of survival in RPSTS.

Influence of specialty and clinical experience on treatment sequencing in the multimodal management of soft tissue extremity sarcoma.

PURPOSE: Although multimodal management of extremity soft tissue sarcoma (STS) is the standard of care, considerable variation exists in the sequencing of radiotherapy (RT) or chemotherapy (CT). Our goal was to identify factors responsible for this variation. METHODS: Members of specialty societies with an interest in STS were emailed a questionnaire about multimodal treatment of STS. Survey responses were scored on a 5-point Likert scale (1 = always preoperative and 5 = always postoperative) and analyzed by specialty, years in practice, and percentage of practice consisting of STS. RESULTS: The questionnaire was completed by 320 (65%) of 490 physicians, including medical oncologists (18%), radiation oncologists (8%), orthopedic oncologists (22%), surgical oncologists (45%), and others (7%). Respondents were evenly split on the use of neoadjuvant RT (mean 3.03 ± 0.06) and showed a slight preference for neoadjuvant CT (2.89 ± 0.06). Radiation oncologists (2.52 ± 0.18), physicians with a >75% STS practice (2.58 ± 0.17), and those in practice <5 years (2.79 ± 0.12) preferred neoadjuvant RT. Neoadjuvant CT was preferred by orthopedic oncologists (2.62 ± 0.12) and physicians with >75% STS practice (2.51 ± 0.16). Factors influencing the choice for neoadjuvant RT were well-defined treatment volume, increased acute morbidity, and decreased late morbidity, while for CT, they were in-situ disease monitoring and early treatment of micrometastases. CONCLUSIONS: Treatment sequencing in STS is influenced by specialty and clinical experience, with no clear consensus. These patterns may reflect the recent trend toward regionalization of STS care.

Pelvic osteoid osteoma in a skeletally mature female.

Osteoid osteoma is the most common bone-producing tumor that typically presents with "throbbing night pain" and that improves dramatically with use of low-dose salicylates. Few cases of pelvic osteoid osteoma have been reported, and most have involved patients younger than age 30. Surgical excision classically has been the treatment of choice, but, recently, less invasive modalities, including radiofrequency ablation, have begun to supplant surgical management of osteoid osteoma, resulting in a decrease in the need for definitive surgical diagnosis and treatment. We present a rare case of osteoid osteoma in the pelvis of a woman older than age 30.

Lack of survival benefit following adjuvant radiation in patients with retroperitoneal sarcoma: a SEER analysis.

BACKGROUND: The benefit of radiation therapy (RT) among patients with retroperitoneal sarcoma (RPS) is controversial. We performed a retrospective analysis of the effect of RT on survival among RPS patients using a nationwide cancer registry. METHODS: Utilizing data from the Surveillance, Epidemiology, and End Results (SEER) database, we identified 2308 cases of RPS from 1988 to 2004. We excluded 773 cases for age < 18, identification by autopsy only, absence of histologic confirmation, presence of metastatic disease, or lack of surgical intervention. Overall survival (OS) and disease-specific survival (DSS) were estimated using the Kaplan-Meier method. Multivariate analysis was performed using a Cox proportional hazards model, adjusting for significant covariables. RESULTS: Among 1535 patients who met entry criteria, RT was administered to 373 patients (24.3%). The majority of RT (n = 300, 80.4%) was administered postoperatively. Median OS was 60 and 60 mo, respectively, for patients receiving and not receiving RT (P = 0.59). Median DSS was 86 and 117 mo, respectively, for patients receiving and not receiving RT (P = 0.84). On multivariate analysis, younger age, female gender, low and intermediate histologic grade, liposarcoma histology, tumor size 5-10 cm, and completeness of resection all independently predicted better OS and DSS, while RT did not (HR for OS with RT 0.92, 95% CI 0.78-1.09 and HR for DSS with RT 0.96, 95% CI 0.78-1.17). On subgroup analysis by histology, patients with malignant fibrous histiocytoma (MFH) receiving RT demonstrated statistically improved OS (P = 0.002) and DSS (P = 0.01), respectively. CONCLUSIONS: With the possible exception of MFH, postoperative RT offers no survival benefit in RPS. Further studies are necessary to determine if the selective application of RT is indicated.

Contiguous organ resection is safe in patients with retroperitoneal sarcoma: An ACS-NSQIP analysis.

BACKGROUND AND OBJECTIVES: The practice of aggressive contiguous organ resection (COR) of retroperitoneal sarcoma (RPS) is controversial. We examined rates of 30-day morbidity and mortality following resection of RPS utilizing data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. METHODS: From 2005 to 2007, we identified 156 cases of primary malignant neoplasm of the retroperitoneum. Univariate and multivariate analyses were performed using all pre-operative ACS-NSQIP variables for likelihood of post-operative overall morbidity or severe morbidity (composite endpoint including organ space infection, septic shock, acute renal failure requiring dialysis, reoperation, and death). Insufficient events precluded multivariate analysis of mortality as an independent outcome. RESULTS: Overall 30-day morbidity, severe morbidity, and mortality were 26% (N = 40), 11.5% (N = 18), and 1.3% (N = 2), respectively. Fifty-eight patients (37%) underwent COR, most commonly kidney. American Society for Anesthesiologists classification predicted overall morbidity (OR 3.23, 95% CI 1.33-7.84), while increasing operative time predicted severe morbidity (OR 1.38 per hour, 95% CI 1.05-1.81). COR was not associated with increased 30-day overall morbidity (OR 1.38, 95% CI 0.49-3.89) or severe morbidity (OR 0.78, 95% CI 0.05-13.18). CONCLUSIONS: Rates of post-operative morbidity and mortality are acceptable following RPS resection, even in the setting of multi-visceral resection. COR should not be viewed as a contraindication to complete RPS resection.

Progression of aggressive metastatic carcinosarcoma after treatment of epithelioid osteosarcoma.

Osteosarcoma is the most common primary malignant osseous neoplasm, constituting approximately 35% of skeletal malignancies. The different subtypes of osteosarcoma are differentiated based on clinical, histologic, and radiographic data, as well as the variable amount of osteoid produced by malignant cells. The epithelioid osteosarcoma subtype accounts for only 5.7% of all osteosarcomas and portends an extremely poor prognosis. The 5-year survival rate for patients with epithelioid osteosarcoma treated with surgery (with or without chemotherapy) is 13.5%. This is in direct contrast to the >70% ten-year survival rate of conventional osteosarcoma treated with surgery and chemotherapy. This article presents a fatal case of epithelioid osteosarcoma in an 11-year-old girl with right knee pain of 6 months' duration. Biopsy demonstrated morphologic findings consistent with high-grade osteosarcoma with epithelioid features. The epithelioid component was positive for vimentin and CD99; however, fluorescent in situ hybridization for the (11;22) translocation was negative. In this case, the epithelioid cells failed to respond to conventional or subsequent experimental chemotherapy for osteosarcoma and eventual metastasized to the lymph nodes and lungs despite multiple ablative surgeries. This case report supports the concept of carcinosarcoma with malignant cells lines arising from 2 different cellular lineages or a common cellular precursor. The epithelial component was more aggressive than the cells of mesenchymal origin, highlighting the need for continued research and a more favorable outcome for this rare subset of osteosarcoma.

Radiographic and histologic response to neoadjuvant radiotherapy in patients with soft tissue sarcoma.

BACKGROUND: Limited data exist regarding the radiographic and histologic response of soft tissue sarcoma (STS) to neoadjuvant radiotherapy (RT). METHODS: Between February 2000 and January 2009, a total of 25 patients aged >16 years with intermediate- or high-grade primary STS of all sites were treated with neoadjuvant RT followed by definitive resection. Patients receiving chemoradiotherapy were excluded. Cross-sectional images obtained before and after RT as well as pathologic specimens were reviewed for maximal change in tumor diameter and percentage tumor necrosis, respectively. Clinicopathologic variables were analyzed for their association with pathologic and radiographic response. RESULTS: There were 18 extremity (72%) and 7 retroperitoneal (28%) tumors. Median maximal tumor size was 9 cm (range, 3.3-35 cm), and 88% were of high grade. There were 21 R0 resections (84%) and 4 R1 resections (16%). Radiographically, the median percentage change in tumor diameter was 0% (range, -25 to +86%). By Response Evaluation Criteria in Solid Tumors (RECIST), 5 patients demonstrated progressive disease, 20 demonstrated stable disease, and 0 demonstrated partial/complete response. The median pathologic percentage tumor necrosis was 30% (range, 5-100%). Two tumors (8%) demonstrated near-complete pathologic response (≥95% necrosis). Near-complete pathologic response was associated with favorable oncologic outcomes, although these associations were not statistically significant. CONCLUSIONS: Radiologic and near-complete pathologic responses are rare events after preoperative RT for STS. Near-complete pathologic response may be a potentially meaningful surrogate marker for disease outcome and is not predicted by RECIST response. Knowledge of these historical response rates is important for the evaluation of novel neoadjuvant therapies for patients with STS.

Percutaneous radionuclide ablation of axial aneurysmal bone cysts.

OBJECTIVE: The purpose of our study was to retrospectively examine the efficacy of intralesional injection of 32P chromic phosphate, a beta-emitting colloidal radiopharmaceutical, in the treatment of aneurysmal bone cysts of the axial skeleton. Five patients with large aneurysmal bone cysts were managed with injection of 32P chromic phosphate into their tumors under CT guidance. With only a single minor complication, all lesions were observed to ossify on follow-up CT, with an average follow up of 2 years. CONCLUSION: CT-guided injection of axial aneurysmal bone cysts with 32P chromic phosphate leads to excellent local lesion control. In addition, the morbidity associated with this procedure is lower than that associated with surgical or other nonsurgical treatments.

Diagnosis and treatment of joint-related tumors that mimic sports-related injuries.

Tumors involving the joint or having symptoms in the joint are rare. Both joint-related tumors and sports-related injuries can affect young, active patients, and their symptoms often overlap. Sports medicine specialists rarely encounter synovial conditions, so expertise in this area is difficult to establish. Orthopaedic oncologists often see only patients with an advanced condition. The clinical presentation of a soft-tissue sarcoma may be similar to that of a common lesion such as a synovial cyst. Some benign or malignant bone tumors cause referred pain to distant joints, possibly leading to a delay in diagnosis or inappropriate initial surgery. For example, a hip or proximal femoral bone tumor commonly causes isolated knee pain. Conversely, because the symptoms of some sports-related conditions or pseudotumors (such as a rectus femoris tear, fascial herniation, myositis ossificans, an avulsion injury, an avulsive cortical irregularity, femoral diaphyseal periostitis, or pseudotumor deltoideus) are similar to symptoms of a sarcoma, overtreatment is possible. A sports medicine physician should be familiar with these conditions to facilitate accurate and expedient diagnosis with appropriate treatment.