Injection granuloma mimicking soft tissue sarcoma following seasonal influenza vaccine administration: A case report.

RATIONALE: Soft tissue masses are common within the general population with a minority diagnosed as soft tissue neoplasms. Differing between benign and malignant soft tissue processes can be a challenge given the overlapping clinical and imaging characteristics. We present the case of a 69-year-old female referred to the Orthopaedic Oncology Service for evaluation of a suspected soft tissue sarcoma in the upper arm. PATIENT CONCERNS: She reported a mass localized over the deltoid with associated tenderness 1 month after influenza vaccination. DIAGNOSIS: After thorough consideration of the patient's clinical course, history, advanced imaging, and physical examination, the diagnosis of injection granuloma associated with recent influenza vaccination was considered. INTERVENTIONS: Biopsy was deferred and close interval follow-up with clinical and imaging evaluation revealed a resolving process. OUTCOMES: The patient was followed until complete resolution of all symptoms, which occurred 5 months after initial presentation. LESSONS: It was hypothesized that due the patient's body habitus, the injection contents intended for intramuscular administration remained in the subcutaneous tissues and elicited a granulomatous reaction. This case highlights several important factors for physicians to consider in the work up of suspicious masses for which injection granuloma is on the differential diagnosis.

Sensitivity of the stress field of the proximal femur predicted by CT-based FE analysis to modeling uncertainties.

Proximal femur anatomy and bone mineral density vary widely among individuals, precluding the use of one predefined finite element (FE) model to determine the stress field for all proximal femurs. This variability poses a challenge in current prosthetic hip design approach. Given the numerous options for generating computed tomography (CT)-based FE models, selecting the best methods for defining the mechanical behavior of the proximal femur is difficult. In this study, a combination of computational and experimental approaches was used to explore the susceptibility of the predicted stress field of the proximal femur to different combinations of density-elasticity relationships, element type, element size, and calibration error. Our results suggest that FE models with first-order voxelized elements generated by the Keyak and Falkinstein density-elasticity relationship or quadratic tetrahedral elements generated by the Morgan density-elasticity relationship lead to accurate estimations of the mechanical behavior of human femurs. Other combinations of element size, element type, and mathematical relationships produce less accurate results, especially in the cortical bone of the femoral neck and calcar region. The voxelized model was more susceptible to variation of element size and density-elasticity relationships than FE models with quadratic tetrahedral elements. Regardless of element type, the stress fields predicted by the Keyak and Falkinstein and the Morgan relationships were the most robust to calibration error when deriving material density from CT-generated Hounsfield data. These results provide insight into the implementation of a robust platform for designing patient-specific implants capable of maintaining or modifying the stress in bones.

Temporal Trends in Hip Fractures: How Has Time-to-Surgery Changed?

BACKGROUND: Surgical fixation of hip fractures within 24-48 hours of hospital presentation is associated with decreased rates of postoperative morbidity and death, and recently, hospitals nationwide have implemented strategies to expedite surgery. Our aim was to describe how time-to-surgery and short-term complication rates have changed using the National Surgical Quality Improvement Program database from 2011 to 2017. METHODS: We identified more than 73,000 patients aged ≥65 years who underwent surgical fixation. Poisson regression adjusting for comorbidities, surgery type, type of anesthesia, patient sex, and patient age was performed to quantify annual changes in time-to-surgery. Annual changes in 30-day postoperative complications were analyzed using a generalized linear model with binomial distribution. RESULTS: A significant decrease in time-to-surgery was observed during the study period (mean 30 hours in 2011 versus 26 hours in 2017; P<0.001). Time-to-surgery decreased by 2% annually during the 7-year period (0.5 hour/year, 95% CI: -35, -23; P<0.001). The all-cause 30-day complication rate also decreased annually (annual risk difference: -0.35%, 95% CI: -0.50%, -0.20%; P<0.001). For individual complications, we found significant decreases in deep infection (-0.2%, P=0.002), reintubation (-0.3%, P=0.001), urinary tract infection (-2.5%, P<0.001), and death (-1.3%, P=0.03). We found significant but small increases of pulmonary embolism (0.3%, P=0.03) and myocardial infarction (0.1%, P=0.02). Higher rates of complications were associated with increased time-to-surgery (P<0.001). CONCLUSION: From 2011 to 2017, time-to-surgery for hip fracture decreased significantly, as did short-term postoperative rates of all-cause complications and death. Longer time-to-surgery was associated with increased number of complications.

Can a Novel Scoring System Improve on the Mirels Score in Predicting the Fracture Risk in Patients with Multiple Myeloma?

BACKGROUND: Stratification of the fracture risk is an important treatment component for patients with multiple myeloma, which is associated with up to an 80% risk of pathologic fracture. The Mirels score, which is commonly used to estimate the fracture risk for patients with osseous lesions, was evaluated in a cohort in which fewer than 15% of lesions were caused by multiple myeloma. The behavior of multiple myeloma lesions often differs from that of lesions caused by metastatic disease, and accurate risk stratification is critical for effective care. To our knowledge, the Mirels score has not been validated specifically for multiple myeloma. QUESTIONS/PURPOSES: Our purpose was: (1) To develop a novel scoring system for the prediction of pathologic fracture in patients with long-bone lesions from multiple myeloma; and (2) to compare the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and receiver operating characteristic (ROC) area under curve (AUC) between the novel scoring system and the Mirels system. METHODS: Between 2003 and 2017, 763 patients at one center with the diagnosis of multiple myeloma were reviewed, of whom 174 presented with long-bone disease involvement. Of those, 5% (nine of 174) were missing data or radiographs at a minimum of 1 year and had not reached an endpoint (fracture or surgery) before that time and were therefore excluded. Many patients have more than one lesion; consequently, we used the largest lesion in each patient, resulting in 163 lesions in as many patients. Ten percent (16 of 163) of these patients eventually developed a fracture and 4% (six of 163) underwent prophylactic stabilization (excluded from analysis because of outcome uncertainty). During the study period, prophylactic stabilization was performed at the discretion of the orthopaedic oncologist. Fifty-one percent (83 of 163) of patients were female, and the mean (± SD) age was 60 ± 10 years at radiographic lesion identification. All lesions were characterized before determining whether the patient underwent pathologic fracture. We identified variables associated with pathologic fracture on univariate analysis. Variables independently significant on logistic regression analysis were used to generate scoring algorithms at varying weights and scoring cutoffs for comparison via ROC curves. We then selected a novel score based on ROC performance, and compared the sensitivity, specificity, PPV, and NPV of that scoring system to that of Mirels score. ROC AUCs were compared after bootstrapping 100,000 iterations. Alpha was set at 0.05. RESULTS: After controlling for potential confounders, such as age, sex, and duration of myeloma diagnosis, we found the following factors were independently associated with the occurrence of pathologic fracture: larger lesion size (area, cm2) (log odds 0.17; p = 0.03), longer lesion latency (years from diagnosis to lesion identification) (log odds 0.25; p = 0.03), presence of pain (relative risk [RR] 2.9; p = 0.04), and metaphyseal location (RR 3.2, compared with epiphyseal or diaphyseal; p = 0.003). These variables were used to formulate a novel scoring system. Compared with the Mirels system, the novel system was more sensitive (69% [95% CI 61 to 76] versus 38% [95% CI 30 to 46]; p < 0.05) but not different in terms of specificity (87% [95% CI 80 to 91] versus 87% [95% CI 81 to 92]; p > 0.05), PPV (37% [95% CI 29 to 45] versus 25% [95% CI 19 to 33]; p > 0.05), NPV (96% [95% CI 91 to 99] versus 92% [95% CI 87 to 96]; p > 0.05), or AUC (0.85 [95% CI 0.74 to 0.92] versus 0.67 [95% CI 0.51 to 0.81]; p > 0.05). CONCLUSION: The novel scoring system was found to be more sensitive than the Mirels system for predicting pathologic fracture in our retrospective cohort of patients with multiple myeloma-related bone disease. Specificity, PPV, NPV, and ROC AUC were not different with the numbers available. Thus, the novel scoring system may serve as a more effective screening tool to determine which patients with multiple myeloma would benefit from further radiologic or orthopaedic evaluation based on a skeletal survey. LEVEL OF EVIDENCE: Level III, diagnostic study.

Management of Scoliosis in Patients With Loeys-Dietz Syndrome.

BACKGROUND: Loeys-Dietz syndrome (LDS) is a genetic connective tissue disorder. We sought to determine the incidence of scoliosis in patients with LDS, characterize the spectrum of spinal deformity, determine the results of bracing and surgery, and define surgical complications. METHODS: Patients were selected from our institution's database of 183 patients with LDS. Imaging measurements were performed for 141 patients whose records permitted spinal evaluation. Deformity changes and complications after intervention were recorded for patients who underwent bracing or surgery, and associations were tested using Student t tests (significance, P<0.05). RESULTS: Eighty-eight of 141 (62%) patients with LDS had scoliosis, with main thoracic and thoracolumbar curves being most common. Fifteen patients were braced (mean age, 9±3 y) for a mean of 2.3 years. They had a mean postbracing curve progression of 12±21 degrees (5±9 deg./y). There were no significant differences in age, sex, curve type, or prebracing curve magnitude between successfully braced (n=4) and unsuccessfully braced (n=11) patients (P>0.05). Nine patients, (mean age, 12±3 y), underwent 24 surgical procedures (16 growing rod procedures, 8 fusions). Mean curve corrections were 61% for growing rods and 73% for fusions. Associated blood loss for these procedures was 400 mL and 1293 mL, respectively, and normalized blood loss for fusion was 2.34 mL/kg/level. Fifteen of 24 surgical procedures involved complications (63%), including cerebrospinal fluid leaks (n=7) and blood loss >20% of estimated total blood volume (n=11). CONCLUSIONS: Scoliosis was present in 62% of our sample of LDS patients. Bracing did not halt curves in 11 of 15 patients, whose curves progressed >5 degrees or to >50 degrees by completion of bracing. At latest follow-up, 47% of the braced patients had undergone surgery after prior bracing attempts. The high blood loss associated with these operations is believed to be related to vascular fragility in patients with LDS. LEVEL OF EVIDENCE: Level IV-retrospective cohort study.

Primary rhabdomyosarcoma of the distal femoral diaphysis: a case report and review of the literature.

Primary rhabdomyosarcoma of the bone is an extremely rare condition with few examples reported in the literature. We present the case of a 34-year-old male who presented with a lesion in the distal femur with initial imaging features consistent with Ewing sarcoma. Histologically, the lesion consisted of atypical pleomorphic polygonal rhabdomyoblasts demonstrating focal desmin and myogenin expression. A diagnosis of pleomorphic rhabdomyosarcoma was rendered. Despite systemic treatment and surgery, this patient experienced a rapidly progressive disease course. We believe this is only the second report in the orthopedic literature of a case of primary pleomorphic rhabdomyosarcoma of the bone. The key imaging, pathologic, and clinical findings are discussed.