Nonfracture Cases Research Articles

Five-Year Mortality Rates Following Elective Shoulder Arthroplasty and Shoulder Arthroplasty for Fracture in Patients Over Age 65.

To effectively counsel patients prior to shoulder arthroplasty, surgeons should understand the overall life trajectory and life expectancy of patients in the context of the patient's shoulder pathology and medical comorbidities. Such an understanding can influence both operative and nonoperative decision-making and implant choices. This study evaluated 5-year mortality following shoulder arthroplasty in patients ≥65 years old and identified associated risk factors. We utilized Centers for Medicare & Medicaid Services Fee-for-Service inpatient and outpatient claims data to investigate the 5-year mortality rate following shoulder arthroplasty procedures performed from 2014 to 2016. The impact of patient demographics, including fracture diagnosis, year fixed effects, and state fixed effects; patient comorbidities; and hospital-level characteristics on 5-year mortality rates were assessed with use of a Cox proportional hazards regression model. A p value of <0.05 was considered significant. A total of 108,667 shoulder arthroplasty cases (96,104 nonfracture and 12,563 fracture) were examined. The cohort was 62.7% female and 5.8% non-White and had a mean age at surgery of 74.3 years. The mean 5-year mortality rate was 16.6% across all shoulder arthroplasty cases, 14.9% for nonfracture cases, and 29.9% for fracture cases. The trend toward higher mortality in the fracture group compared with the nonfracture group was sustained throughout the 5-year postoperative period, with a fracture diagnosis being associated with a hazard ratio of 1.63 for mortality (p < 0.001). Medical comorbidities were associated with an increased risk of mortality, with liver disease bearing the highest hazard ratio (3.07; p < 0.001), followed by chronic kidney disease (2.59; p < 0.001), chronic obstructive pulmonary disease (1.92; p < 0.001), and congestive heart failure (1.90; p < 0.001). The mean 5-year mortality following shoulder arthroplasty was 16.6%. Patients with a fracture diagnosis had a significantly higher 5-year mortality risk (29.9%) than those with a nonfracture diagnosis (14.9%). Medical comorbidities had the greatest impact on mortality risk, with chronic liver and kidney disease being the most noteworthy. This novel longer-term data can help with patient education and risk stratification prior to undergoing shoulder replacement. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Interpretable machine learning text classification for clinical computed tomography reports – a case study of temporal bone fracture

BackgroundMachine learning (ML) has demonstrated success in classifying patients’ diagnostic outcomes in free-text clinical notes. However, due to the machine learning model's complexity, interpreting the mechanism behind classification results remains difficult. MethodsWe investigated interpretable representations of text-based machine learning classification models. We created machine learning models to classify temporal bone fractures based on 164 temporal bone computed tomography (CT) text reports. We adopted the XGBoost, Support Vector Machine, Logistic Regression, and Random Forest algorithms. To interpret models, we used two major methodologies: (1) We calculated the average word frequency score (WFS) for keywords. The word frequency score shows the frequency gap between positively and negatively classified cases. (2) We used Local Interpretable Model-Agnostic Explanations (LIME) to show the word-level contribution to bone fracture classification. ResultsIn temporal bone fracture classification, the random forest model achieved an average F1-score of 0.93. WFS revealed a difference in keyword usage between fracture and non-fracture cases. Additionally, LIME visualized the keywords' contributions to the classification results. The evaluation of LIME-based interpretation achieved the highest interpreting accuracy of 0.97. ConclusionThe interpretable text explainer can improve physicians' understanding of machine learning predictions. By providing simple visualization, our model can increase the trust of computerized models. Our model supports more transparent computerized decision-making in clinical settings.

Impact of the COVID-19 pandemic on shoulder arthroplasty: surgical trends and postoperative care pathway analysis.

IntroductionCOVID-19 triggered disruption in the conventional care pathways for many orthopedic procedures. The current study aims to quantify the impact of the COVID-19 pandemic on shoulder arthroplasty hospital surgical volume, trends in surgical case distribution, length of hospitalization, post-hospital disposition, and 30-day readmission rates.MethodsThis study queried all Medicare (100% sample) fee-for-service beneficiaries who underwent a shoulder arthroplasty procedure (DRG 483, CPT 23472) from January 1, 2019 to December 18, 2020. Fracture cases were separated from non-fracture cases, which were further subdivided into anatomic or reverse arthroplasty. Volume per 1000 Medicare beneficiaries was calculated from April to December 2020 and compared to the same months in 2019. Length of stay (LOS), discharged-home rate, and 30-day readmission for the same period were obtained. The yearly difference adjusted for age, sex, race (white vs. non-white), CMS-Hierarchical Condition Categories (HCC) risk score, month fixed effects, and Core-based Statistical Area (CBSA) fixed effects, with standard errors clustered at the provider level was calculated using a multivariate analysis (p < 0.05).Results49,412 and 41,554 TSA cases were observed April through December for 2019 and 2020, respectively. There was an overall decrease in shoulder arthroplasty volume per 1000 Medicare beneficiaries by 14% (19% reduction in anatomic TSA, 13% reduction in RTSA, and 3% reduction in fracture cases). LOS for all shoulder arthroplasty cases decreased by 16% (-0.27 days, p< 0.001) when adjusted for confounders. There was a 5% increase in the discharge-home rate (88.0% to 92.7%, p<0.001); most prominent in fracture cases with a 20% increase in discharged-home cases (65.0% to 73.4%, p<0.001). There was no significant change in 30-day hospital readmission rates overall (p = 0.20) or when broken down by individual procedures.ConclusionsThere was an overall decrease in shoulder arthroplasty volume per 1000 Medicare beneficiaries by 14% during the COVID-19 pandemic. A decrease in LOS and increase in the discharged-home rates was also observed with no significant change in 30-day hospital readmission, indicating that a shift towards an outpatient surgical model can be performed safely, efficiently and has potential to provide value.

MRI evaluation of pediatric tibial eminence fractures: comparison between conventional and "CT-like" ultrashort echo time (UTE) images.

UTE MRI offers a radiation-free alternative to CT for bone depiction, but data on children is lacking. The purpose of this study was to determine whether UTE images improve detection and characterization of pediatric tibial eminence fractures. Fifteen MRIs with UTE from 12 children (10 boys, 2 girls; mean age: 12.6 ± 3.3years) with tibial eminence fractures (2018-2020) and 15 age-matched MRIs without fractures were included. After randomization, 5 readers reviewed images without and with UTE, at least 1month apart, and recorded the presence of fracture and preferred images. If fracture ispresent, radiologists also recorded fragment size, number, and displacement; surgeons assigned Meyers-McKeever grade and management. Disagreements on management were resolved through consensus review. Kappa and intra-class correlation (ICC), sensitivity, and specificity were used to compare agreement between readers and fracture detection between images without and with UTE. For fracture detection, inter-reader agreement was almost perfect (κ-range: 0.91-0.93); sensitivity and specificity were equivalent between images without and with UTE (range: 95-100%). For fracture characterization, UTE improved agreement on size (ICC = 0.88 to 0.93), number (ICC = 0.52 to 0.94), displacement (ICC = 0.74 to 0.86), and grade (ICC = 0.92 to 0.93) but reduced agreement on management (κ = 0.68 to 0.61), leading to a change in consensus management in 20% (3/15). Radiologists were more likely to prefer UTE for fracture and conventional images for non-fracture cases (77% and 77%, respectively, p < 0.001). While UTE did not improve diagnosis, it improved agreement on characterization of pediatric tibial eminence fractures, ultimately changing the preferred treatment in 20%.

Dual-energy CT-generated bone marrow oedema maps improve timely visualisation and recognition of acute lower extremity fractures

To assesses whether utilising bone marrow oedema (BMO) maps improved fracture read times and reader confidence in a large series of acute lower extremity trauma dual-energy computed tomography (DECT) studies. One hundred and six DECT studies, including 60 fracture cases and 46 non-fracture cases, were evaluated retrospectively in this cross-sectional study. Three-dimensional (3D) BMO maps were generated for each study and coded to display skeletal anatomy in blue and marrow oedema in green. Studies were interpreted by two readers in two timed stages (without and with BMO maps). Readers identified the number, anatomical location, and comminution of fractures. Reader confidence (five-point Likert scale) for fracture identification and anatomical regions where oedema was present was also recorded. Decreased read times (p<0.01) were observed when readers utilised BMO maps for their fracture search. The presence of oedema on BMO maps corresponded with associated fracture in 75.7% reads. No differences in reader confidence were observed as a result of using this BMO-guided technique (>95%, 5/5 for both readers with and without the aid of BMO maps). DECT BMO maps improve the speed of radiological identification of suspected acute lower extremity fractures with preserved reader confidence. It may help emergent detection of fractures, important for patient management and outcomes.

Lower Extremity Compartment Syndrome in National Football League Athletes.

The purpose of this study was to evaluate the incidence of lower extremity compartment syndrome in National Football League (NFL) athletes and report the mechanisms of injury, methods of treatment, and subsequent days missed. We review the existing literature on lower extremity compartment syndrome in athletic populations. Lower extremity compartment syndrome occurs with a low incidence in NFL athletes, and there is a high return-to-play rate after surgical management of acute compartment syndrome. Case series. Level 4. A retrospective review of recorded cases of lower extremity compartment syndrome from 2000 to 2017 was performed using the NFL Injury Surveillance System and electronic medical record system. Epidemiological data, injury mechanism, rates of surgery, and days missed due to injury were recorded. During the study period, 22 cases of leg compartment syndrome in 21 athletes were recorded. Of these injuries, 50% occurred in games and 73% were the result of a direct impact to the leg. Concomitant tibial fracture was noted in only 2 cases (9.1%) and there was only 1 reported case of chronic exertional compartment syndrome. Surgery was documented in 15 of 22 cases (68.2%). For acute nonfracture cases, the average time missed due to injury was 24.2 days (range, 5-54 days), and all were able to return to full participation within the same season. NFL athletes with acute leg compartment syndrome treated with surgery exhibited a high rate of return to play within the same season. Although compartment syndrome is a relatively rare diagnosis among NFL players, team physicians and athletic trainers must maintain a high index of suspicion to expediently diagnose and treat this potentially limb-threatening condition.

Differences in Femoral Neck and Trochanteric Structure in Elderly Women Prior to Hip Fracture: Role in Hip Fracture Prediction.

We examine the hypothesis that internal dual-energy X-ray absorptiometry (DXA) structural variables measured at the femoral neck and trochanter cross sections will improve prediction of fractures at these sites in addition to areal BMD (aBMD). We present an analysis of the internal distribution of bone at the site of these fractures using baseline hip DXA measurement of 1151 participants, mean age (SD) 75 (3) years, in the 14.5-year Perth Longitudinal Study of Aging in Women. Structural differences at the femoral neck (FN) and trochanter (TR) cross sections were compared in 69 participants who went on to sustain femoral neck fracture (FNF) and 59 participants who went on to sustain trochanter fracture (TRF), on average 10 years later, to those who did not fracture. The new structural variables, in addition to aBMD and bone width (W), were Sigma (distribution of bone within scanned area) and Delta (distance between center-of-mineral mass and geometric center), which can be assessed by current DXA programs. At baseline, compared with nonfracture cases, FNF cases had a FNaBMD 7% lower, a FNWidth 3% higher and a FNDelta 29% higher, associated with reduced bone in the superior segment. In FNF Cox proportional hazard analysis, age (hazard ratio [HR 1.39]), total hip aBMD (THaBMD; 0.79), and Delta (1.70) were significant. Addition of FN Delta to the base case of THaBMD and age improved the C statistic from 0.62 to 0.69, p = 0.01. At baseline, TRF cases had a 15% lower TRaBMD with minor differences in Sigma (1%) and Width (2%). In TRF Cox analysis, neither addition of Sigma nor Width improved the model that included age and THaBMD as predictors and did not alter the C-statistic of 0.81. In conclusion, adding measurement of FN Delta, an assessment of superior sector bone loss, to hip aBMD and age substantially improved clinical FNF prediction in older women. © 2023 American Society for Bone and Mineral Research (ASBMR).

Bone Turnover Markers and Bone Mineral Density to Predict Osteoporotic Fractures in Older Women: A Retrospective Comparative Study

ObjectiveTo investigate the clinical significance of the detection of bone mineral density (BMD) and bone turnover markers (BTM) in older women with osteoporosis, and to compare their predictive power for osteoporotic fractures (OF).MethodsIn this retrospective study, 96 patients with OF and 107 patients with osteoporosis who were hospitalized in the Department of Orthopedics at the First Affiliated Hospital of Chengdu Medical College were examined from October 2017 to February 2019. All selected patients were divided into either the fracture group (96 cases, 47.3%) or the non‐fracture group (107 cases, 52.7%). BMD was measured by dual‐energy X‐ray absorptiometry (DXA). BTM were detected by electrochemical luminescence: aminoterminal propeptide of type I procollagen (PINP), β‐cross‐linked C‐telopeptide of type I collagen (β‐CTX), and molecular fragment of osteocalcin N terminal (N‐MID). Bone metabolism‐related indicators were detected, including alkaline phosphatase (ALP), calcium (Ca), and phosphorus (P). Independent‐samples t‐tests were used to compare the measurement data between the two groups, one‐way ANOVA to compare the gaps between groups, and binary logistic regression to analyze the correlation of BMD and BTM with OF.ResultsThere were no significant differences in age, weight, height, body mass index, age, and time of menopause between the two groups. There were a total of 71 cases (35.0%) in group A (60–70 years), 80 cases (39.4%) in group B (71–80 years), and 52 cases (25.6%) in group C (81–90 years). The fracture group was compared with the non‐fracture group for BMD in the lumbar (0.75 ± 0.05 vs 0.88 ± 0.13, 0.75 ± 0.16 vs 0.87 ± 0.09, 0.74 ± 0.21 vs 0.87 ± 0.12 g/cm2; P < 0.05), BMD in the hip (0.62 ± 0.16 vs 0.74 ± 0.14, 0.61 ± 0.15 vs 0.73 ± 0.0, 0.58 ± 0.13 vs 0.73 ± 0.08 g/cm2; P < 0.05), PINP (83.7 ± 5.7 vs 74.8 ± 5.0, 80.7 ± 4.1 vs 72.1 ± 5.1, 81.2 ± 7.0 vs 68.7 ± 6.3 ng/mL, P < 0.05), and β‐CTX (829.7 ± 91.5 vs 798.8 ± 52.2, 848.1 ± 71.2 vs 812.4 ± 79.0, 867.3 ± 53.1 vs 849.1 ± 67.2 pg./mL, P < 0.05). N‐MID (19.0 ± 6.7 vs 21.3 ± 9.7, 16.2 ± 7.0 vs 18.0 ± 5.3 ng/mL, P < 0.05) in the fracture cases was lower than in the non‐fracture cases for groups B and C, and there was statistical significance. Among the fracture cases, PINP in group A was higher than in group B and C, and β‐CTX in group C was higher than in group A and B (P < 0.05). There was no significant difference in the ALP, P, and Ca between the two groups (P > 0.05). Binary logistic regression analysis showed that for BMD in the lumbar and hip, β‐CTX and OF were significantly correlated (respectively, odds ratio [OR] = −4.182, 95% confidence interval [CI] 1.672–3.448; OR = 6.929, 95% CI 2.586–12.106; OR = 7.572, 95% CI 1.441–3.059), and the differences were statistically significant. PINP and N‐MID were correlated with OF (respectively, OR = 4.213, 95% CI 0.978–1.005; OR = 2.510, 95% CI 1.070–1.134, P > 0.05), the difference was not statistically significant.ConclusionOsteoporotic older women, with lower bone density and higher β‐CTX, are more likely to incur OF. β‐CTX is better than BMD at predicting OF and can help in its management and in implementing interventions in high‐risk populations.

Changes in bone metabolic profile associated with pregnancy or lactation

Calcium and nutrients are transferred from mothers to fetuses or infants during pregnancy or lactation, respectively, promoting metabolic changes in the mother, many uncharacterized. To evaluate these changes, we undertook two parallel studies. In one we analyzed fourteen clinical cases of vertebral fragility fractures, at or before three months after partum, in mothers who breastfed their infants. In the other, we enrolled 79 additional pregnant subjects, some who chose to breastfeed and others who did not, and analyzed changes in bone metabolic status starting between 34 and 36 weeks of gestation and ending one month after partum. In the larger group, bone-resorbing and bone-forming parameters such as serum TRACP5b and osteocalcin, respectively, significantly increased after partum. Among parameters that changed after partum, serum PTH and the bone-resorbing markers serum TRACP5b and urine NTX were significantly higher in mothers who only breastfed infants compared to mothers who fed infants formula or a mix of both. However, bone-forming parameters were comparable between breastfeeding and non-breast-feeding groups after partum, suggesting that elevated bone-resorption occurs only in the breastfeeding group. Radiographic analysis after partum demonstrated that no subject among the 79 analyzed showed vertebral fractures, even those who breastfed exclusively. Among fracture cases analyzed, subjects exhibited significantly lower bone mineral density than did non-fracture cases in breastfeeding-only subjects. We conclude that bone metabolic status significantly changes over the period between pregnancy and post-partum lactation, and that low bone mineral density seen in a small subset of breastfeeding-only cases likely causes post-partum vertebral fragility fractures.

Orthopaedic Residents' Interpretation of Point-of-Care Assessment of Distal Radial Fractures with Use of Pocket-Sized Ultrasound Devices.

Musculoskeletal ultrasonography is a tool that is being used increasingly. However, the interpretation of ultrasound images of fractures is not incorporated into orthopaedic training programs. This paper presents the results of an initiative to train orthopaedic surgery residents to accurately interpret images of distal radial fractures in adults and to assess their confidence levels and attitudes regarding their future use of ultrasonography. Six junior residents were given a pretest with 100 distal radial images that had been made with a pocket-sized ultrasound device; they were asked to determine fracture versus nonfracture cases (50 cases) as well as reduced fracture versus nonreduced fracture cases (50 cases). Following the pretest, residents completed a 30-minute tutorial (didactic and practical) on distal radial ultrasonography. The residents then completed a period of self-practice during 2 separate trauma rotations (a total of 14 to 16 weeks in a single academic year). Following completion of their second trauma rotation, the residents completed a posttest. Comfort level using a pocket-sized ultrasound device also was assessed during pretesting and posttesting. The median number of days from the pretest to the posttest was 212 days (range, 175 to 225 days). Residents demonstrated an overall improvement in positive predictive value (PPV) of identifying a fracture from the pretest (86.0%; range, 77.5% to 93.1%) to the posttest (93.5%; range, 91.4% to 94.2%). The overall negative predictive value (NPV) for identifying a fracture also improved from the pretest (69.4%; range, 60.0% to 76.9%) to the posttest (81.0%; range, 76.4% to 86.7%; p = 0.04). The overall PPV for detecting a reduced fracture improved from 67.1% with the pretest (range, 54.2% to 82.4%) to 88.9% with the posttest (range, 83.3% to 94.1%; p = 0.04). The comfort level with using the ultrasound device also increased between pretesting and posttesting, and the residents felt that ultrasonography would be useful in the care of distal radial fractures. After a focused training session and a period of self-practice, orthopaedic residents improved their interpretation of ultrasound images and their comfort level using pocket-sized ultrasound devices with adult patients with distal radial fractures. Residents felt that a pocket-sized ultrasound device was useful for fracture diagnosis and evaluation of reduction.

Automatic Disease Annotation From Radiology Reports Using Artificial Intelligence Implemented by a Recurrent Neural Network

Radiology reports are rich resources for biomedical researchers. Before utilization of radiology reports, experts must manually review these reports to identify the categories. In fact, automatically categorizing electronic medical record (EMR) text with key annotation is difficult because it has a free-text format. To address these problems, we developed an automated system for disease annotation. Reports of musculoskeletal radiography examinations performed from January 1, 2016, through December 31, 2016, were exported from the database of Hanyang University Medical Center. After sentences not written in English and sentences containing typos were excluded, 3032 sentences were included. We built a system that uses a recurrent neural network (RNN) to automatically identify fracture and nonfracture cases as a preliminary study. We trained and tested the system using orthopedic surgeon-classified reports. We evaluated the system for the number of layers in the following two ways: the word error rate of the output sentences and performance as a binary classifier using standard evaluation metrics including accuracy, precision, recall, and F1 score. The word error rate using Levenshtein distance showed the best performance in the three-layer model at 1.03%. The three-layer model also showed the highest overall performance with the highest precision (0.967), recall (0.967), accuracy (0.982), and F1 score (0.967). Our results indicate that the RNN-based system has the ability to classify important findings in radiology reports with a high F1 score. We expect that our system can be used in cohort construction such as for retrospective studies because it is efficient for analyzing a large amount of data.

3D patient-specific finite element models of the proximal femur based on DXA towards the classification of fracture and non-fracture cases.

Osteoporotic bone fractures reduce quality of life and drastically increase mortality. Minimally irradiating imaging techniques such as dual-energy X-ray absorptiometry (DXA) allow assessment of bone loss through the use of bone mineral density (BMD) as descriptor. Yet, the accuracy of fracture risk predictions remains limited. Recently, DXA-based 3D modelling algorithms were proposed to analyse the geometry and BMD spatial distribution of the proximal femur. This study hypothesizes that such approaches can benefit from finite element (FE)-based biomechanical analyses to improve fracture risk prediction. One hundred and eleven subjects were included in this study and stratified in two groups: (a) 62 fracture cases, and (b) 49 non-fracture controls. Side fall was simulated using a static peak load that depended on patient mass and height. Local mechanical fields were calculated based on relationships between tissue stiffness and BMD. The area under the curve (AUC) of the receiver operating characteristic method evaluated the ability of calculated biomechanical descriptors to discriminate fracture and control cases. The results showed that the major principal stress was better discriminator (AUC > 0.80) than the volumetric BMD (AUC ≤ 0.70). High discrimination capacity was achieved when the analysis was performed by bone type, zone of fracture and gender/sex (AUC of 0.91 for women, trabecular bone and trochanter area), and outcomes suggested that the trabecular bone is critical for fracture discrimination. In conclusion, 3D FE models derived from DXA scans might significantly improve the prediction of hip fracture risk; providing a new insight for clinicians to use FE simulations in clinical practice for osteoporosis management.

X-Ray and Ultrasonography in Forearm Trauma

Introduction This study aimed to prevent unnecessary exposure to ionising radiation, and to exclude non-fracture cases in children admitted to the emergency department with a forearm trauma, by showing that forearm trauma could be assessed with ultrasonography (USG) as accurately and precisely as with direct radiography. Methods A total of 105 patients (67 males and 38 females) were included in the study. Before performing radiography, the patients were assessed with USG and the results were recorded. The findings of USG and radiography were then compared. Results A total of 58 (55%) patients had fractures detected with USG. When compared to X-ray, the sensitivity of USG in detecting forearm fractures was 98.3% (95% confidence interval [CI]: 90.7-100%), specificity was 95.8% (95% CI: 86.0-98.9%), negative likelihood ratio was 0.018, positive likelihood ratio was 23.58, negative predictive value was 97.9% (95% CI: 88.7-99.9%), and positive predictive value was 96.6% (95% CI: 88.1-99.6%). Conclusion The use of USG on selected cases of paediatric patients may provide a more rapid evaluation so as to reduce exposure to ionising radiation. We believe that USG will be useful in excluding non-fracture cases. (Hong Kong j.emerg.med. 2015;22:352-358)

Simulating activities of daily living with finite element analysis improves fracture prediction for patients with metastatic femoral lesions.

Predicting fracture risk for patients with metastatic femoral lesions remains an important clinical problem. Mirels' criterion remains the most formalized radiographic scoring system with good sensitivity (correctly identifying clinical fractures) but relatively poor specificity (correctly identify cases that do not fracture). A series of patients with metastatic femoral lesions had Computed Tomography (CT) scans, were followed prospectively for 4 months, and categorized into fracture (n = 5), non-fracture (n = 28), or stabilized (n = 11) groups. CT based-Finite Element (FE) modeling was used to predict fracture for these cases using axial compression (AC), level walking (LW), and aggressive stair ascent (ASA) loading conditions. The FE predicted fracture force was greater for the non-fracture compared to the fracture group for all loading cases. The ability of the FE models to predict fracture cases (sensitivity) was similar for the groups (Mirels, AC, LW: 80%, ASA: 100%). The ability of the models to correctly predict the non-fracture cases (specificity) was improved for AC (71%) and LW (86%) loading conditions, when compared to Mirels specificity (43%), but poorer for the ASA (21%) conditions. The results suggest that FE models that assess fracture risk using LW conditions can improve fracture prediction over Mirels scoring in a clinical population.

Association of Serum Uric Acid and Incident Nonspine Fractures in Elderly Men: The Osteoporotic Fractures in Men (MrOS) Study

Uric acid (UA) is produced from purines by the enzyme xanthine oxidase, and elevated levels may cause arthritis and kidney stones. Conversely, UA also appears to function as an antioxidant and may protect against the oxidative stress associated with aging and disease. We performed a prospective fracture case-cohort study to understand the relation of UA and fracture risk in older men enrolled in the Osteoporotic Fractures in Men (MrOS) study. In the cohort of 5994 men aged 65 years and older attending the baseline MrOS examination, we evaluated a subgroup 1680 men in a case-cohort study design. The analytic group included 387 men with incident nonspine fractures (73 hip) and a random sample of 1383. Serum UA was measured in baseline serum samples. Modified proportional hazards models that account for case-cohort study design were used to estimate the relative hazards (RH) of hip and nonspine fracture in men for serum UA. Models were adjusted for age, race, clinic site, body mass index, vitamin D, parathyroid hormone, walking speed, Physical Activity Scale for the Elderly (PASE) score, frailty, and total. Subjects with incident nonspine fractures were older, had lower total hip bone mineral density (BMD), and higher serum phosphorus. There was an 18% decreased risk of nonspine fractures (95% confidence interval [CI] 0.71-0.93; p = 0.003) per 1 SD increase of baseline serum and 34% decreased risk of nonspine fractures in quartile 4 of UA versus quartiles 1, 2, and 3 (95% CI 0.49-0.89; p = 0.028) compared with nonfracture cases after multivariate adjustment. Hip fractures were not significantly associated with UA. Total hip BMD was significantly higher in the group of men with high UA levels compared with lower UA levels and increased linearly across quartiles of UA after multivariate adjustment (p for trend = 0.002). In summary, higher serum UA levels were associated with a reduction in risk of incident nonspine fractures but not hip fractures and higher hip BMD.

Do Obesity and/or Stripe Wear Increase Ceramic Liner Fracture Risk? An XFEM Analysis

Hypothesized risk factors for fracture of ceramic liners include impingement, edge-loading, and cup malpositioning. These risk factors are similar to those for generation of stripe wear. However, it is unclear whether the biomechanical conditions contributing to stripe wear generation also increase the risk for ceramic liner fracture We asked whether (1) head stripe wear propensity; and (2) cup orientation would correlate with alumina liner fracture risk for instances of normal and elevated body weight. An eXtended Finite Element Method (XFEM) model was developed to investigate these mechanisms. Liner fracture risk for 36-mm alumina bearings was studied by simulating two fracture-prone motions: stooping and squatting. Twenty-five distinct cup orientations were considered with variants of both acetabular inclination and anteversion. Four separate body mass indices were considered: normal (25kg/m(2)) and three levels of obesity (33, 42, and 50kg/m(2)). Material properties were modified to simulate alumina with and without the presence of dispersed microflaws. The model was validated by corroboration with two previously published ceramic liner fracture studies. Of 200 XFEM simulations with flaw-free alumina, fracture occurred in eight instances, all of them involving obesity. Each of these occurred with cups in≤37° inclination and in 0° anteversion. For 200 corresponding simulations with microflawed alumina, fracture propensity was greatest for cups with higher (edge loading-associated) scraping wear. Fracture risk was greatest for cups with lower inclination (average 42° for fractured cases versus 48° for nonfractured cases) and lower anteversion (9° versus 20°). Fracture propensity for 36-mm liners was elevated for cups with decreased anteversion and/or inclination and under conditions of patient obesity. Factors causing stripe wear, including obesity and cup malpositioning, also involve increased risk of ceramic liner fracture and merit heightened concern.

Finite Element Analysis of the Proximal Femur and Hip Fracture Risk in Older Men

Low areal BMD (aBMD) is associated with increased risk of hip fracture, but many hip fractures occur in persons without low aBMD. Finite element (FE) analysis of QCT scans provides a measure of hip strength. We studied the association of FE measures with risk of hip fracture in older men. A prospective case-cohort study of all first hip fractures (n = 40) and a random sample (n = 210) of nonfracture cases from 3549 community-dwelling men > or =65 yr of age used baseline QCT scans of the hip (mean follow-up, 5.6 yr). Analyses included FE measures of strength and load-to-strength ratio and BMD by DXA. Hazard ratios (HRs) for hip fracture were estimated with proportional hazards regression. Both femoral strength (HR per SD change = 13.1; 95% CI: 3.9-43.5) and the load-to-strength ratio (HR = 4.0; 95% CI: 2.7-6.0) were strongly associated with hip fracture risk, as was aBMD as measured by DXA (HR = 5.1; 95% CI: 2.8-9.2). After adjusting for age, BMI, and study site, the associations remained significant (femoral strength HR = 6.5, 95% CI: 2.3-18.3; load-to-strength ratio HR = 4.3, 95% CI: 2.5-7.4; aBMD HR = 4.4, 95% CI: 2.1-9.1). When adjusted additionally for aBMD, the load-to-strength ratio remained significantly associated with fracture (HR = 3.1, 95% CI: 1.6-6.1). These results provide insight into hip fracture etiology and demonstrate the ability of FE-based biomechanical analysis of QCT scans to prospectively predict hip fractures in men.

Prediction of hip and other osteoporotic fractures from hip geometry in a large clinical cohort

Incident hip fractures and non-hip osteoporotic fractures were studied in 30,953 women during mean 3.7 years of observation. Hip axis length (HAL) and strength index (SI) made a small but statistically significant contribution to hip fracture prediction that was independent of age and hip bone density. It is uncertain whether bone geometric measures improve fracture prediction independent of conventional areal bone mineral density (BMD). Women aged > or =50 years with hip dual-energy x-ray absorptiometry were identified from the regionally based database in the Province of Manitoba, Canada. Scans were reprocessed to derive parameters of hip bone geometry. Incident hip fractures (N = 270) and non-hip osteoporotic fractures (N = 1,347) were identified during mean 3.7 years of observation. HAL was greater in both hip and non-hip fracture cases than in non-fracture cases, whereas cross-sectional moment of inertia, cross-sectional area, and femoral SI were all significantly less. After adjustment for total hip BMD, HAL [hazard ratio (HR) 1.22 per SD increase, 95% CI 1.07-1.38] and SI (HR 1.21 per SD decrease, 95% CI 1.07-1.37) were independent predictors of hip fractures but not of non-hip fractures. When both HAL and SI were added to a model containing age and total hip BMD, there was a small improvement in hip fracture prediction (ROC area under the curve 0.832 +/- 0.013 vs 0.823 +/- 0.013; P = 0.001). HAL and SI made a small but statistically significant contribution to hip fracture prediction that was independent of age and BMD measurement.

Using Radon transform of standard radiographs of the hip to differentiate between post-menopausal women with and without fracture of the proximal femur

Texture features based on the Radon transform were extracted from clinical radiographs of the hip in post-menopausal women. The novel algorithm allowed us to identify patients with fracture of the proximal femur and may provide an alternative to measuring bone mineral density in predicting the fracture-risk in osteoporosis, especially where densitometry is regionally unavailable. The aim of this study is to introduce an algorithm for differentiation between patients with and without fracture of the hip using parameters based on the Radon transform (RT) and applied to standard radiographs of the proximal femur and to compare the results with bone mineral density (BMD). The study comprised 50 post-menopausal women (78.6 +/- 11.5 years of age), including 25 patients with hip fracture and 25 age-matched controls. We obtained lumbar and femoral BMD and standard femoral radiographs. In the radiographs we analysed trabecular patterns of the hip in a region-of-interest of 57 x 29 mm using the RT. From the histogram-representation of the RT, we extracted several characteristic parameters. By ROC and discriminant-analysis, we assessed the statistical power of both methods. For correct differentiation between fracture and non-fracture cases by femoral BMD, area-under-the-curve (AUC) was 0.78; AUC for the RT-based parameters ranged from 0.73 to 0.8. By combination of densitometric and textural information in a multivariate model the fracture status of 84% of subjects was predicted correctly, identification of fracture cases rose to 88%. Identification of fracture patients by RT applied to femoral radiographs was feasible and seemed to have a discriminative potential comparable to that of standard densitometry. In the future, the new method may provide an alternative to DXA or in conjunction with conventional densitometry may enhance the detection of patients with elevated risk of hip fracture.

Risk Assessment and Fracture Discrimination by Ultrasound: The Debate Continues

Risk Assessment and Fracture Discrimination by Ultrasound: The Debate Continues