Cortical bone thickness of the distal radius predicts the local bone mineral density

Development of an opportunistic diagnostic prediction algorithm for osteoporosis and fragility fracture risk estimates from forearm radiographs (The OFFER1 Study)

Osteoporosis and associated fractures are an increasingly prevalent concern with an ageing population. This study reports testing of IBEX Bone Health (IBEX BH) software, applied following acquisition of forearm radiographs. IBEX Bone Health analyses the radiograph to measure areal bone mineral density (aBMD) at the examination site. A non-randomized cross-sectional study design was performed involving 261 (254 after exclusions) participants (112/142 m/f; mean age 70.8 years (SD+/-9.0); 53 with osteoporosis). They underwent posterior-anterior distal forearm radiographs; dual X-ray absorptiometry (DXA) of the wrists, hips, and lumbar spine; and questionnaires exploring clinical risk factors. IBEX Bone Health automatically identifies regions of interest (ROI) at the ultra-distal (UD) and distal third (TD) regions of the radius. Analysis investigated area under the receiver operating characteristics curve performance of IBEX BH for prediction of (i) osteoporosis (based on clinical reporting of the hip and spine DXA) and (ii) treatment recommendations by Fracture Risk Assessment Tool (FRAX) inclusive of neck of femur (NoF) areal bone mineral density (aBMD) results following National Osteoporosis Guideline Group (NOGG) guidelines. Area under the receiver operating characteristics curve for osteoporosis prediction at the UD and TD ROIs were 0.86 (99% confidence interval (CI) [0.80, 0.91]) and 0.81 (99% CI [0.75, 0.88]), respectively. Area under the receiver operating characteristics curve for treatment recommendation using FRAX inclusive of NoF aBMD at the UD and TD ROIs were 0.95 (99% CI [0.91, 1.00]) and 0.97 (99% CI [0.93,1.00]), respectively. With a matched sensitivity to FRAX (without NoF aBMD) 0.93 (99% CI [0.78, 0.99]), IBEX BH predicted at the UD and TD ROIs recommended treatment outcomes by NOGG guidelines using FRAX (with NoF aBMD) with specificity 0.89 (99% CI 0.83, 0.94]) and 0.93 (99% CI [0.87, 0.97]), respectively. This is compared with 0.60 (99% CI [0.51, 0.69]) for FRAX (without NoF aBMD). Results demonstrate the potential clinical utility of IBEX BH as an opportunistic screening tool.

Development and validation of an open-source tool for opportunistic screening of osteoporosis from hip CT images

Aims

This study aimed to develop and validate a fully automated system that quantifies proximal femoral bone mineral density (BMD) from CT images.

Methods

The study analyzed 978 pairs of hip CT and dual-energy X-ray absorptiometry (DXA) measurements of the proximal femur (DXA-BMD) collected from three institutions. From the CT images, the femur and a calibration phantom were automatically segmented using previously trained deep-learning models. The Hounsfield units of each voxel were converted into density (mg/cm3). Then, a deep-learning model trained by manual landmark selection of 315 cases was developed to select the landmarks at the proximal femur to rotate the CT volume to the neutral position. Finally, the CT volume of the femur was projected onto the coronal plane, and the areal BMD of the proximal femur (CT-aBMD) was quantified. CT-aBMD correlated to DXA-BMD, and a receiver operating characteristic (ROC) analysis quantified the accuracy in diagnosing osteoporosis.

Results

CT-aBMD was successfully measured in 976/978 hips (99.8%). A significant correlation was found between CT-aBMD and DXA-BMD (r = 0.941; p < 0.001). In the ROC analysis, the area under the curve to diagnose osteoporosis was 0.976. The diagnostic sensitivity and specificity were 88.9% and 96%, respectively, with the cutoff set at 0.625 g/cm2.

Conclusion

Accurate DXA-BMD measurements and diagnosis of osteoporosis were performed from CT images using the system developed herein. As the models are open-source, clinicians can use the proposed system to screen osteoporosis and determine the surgical strategy for hip surgery.

Thickness of simple calcaneal tuberosity avulsion fractures influences the optimal fixation method employed

Aims

This study aimed to establish the optimal fixation methods for calcaneal tuberosity avulsion fractures with different fragment thicknesses in a porcine model.

Methods

A total of 36 porcine calcanea were sawed to create simple avulsion fractures with three different fragment thicknesses (5, 10, and 15 mm). They were randomly fixed with either two suture anchors or one headless screw. Load-to-failure and cyclic loading tension tests were performed for the biomechanical analysis.

Results

This biomechanical study predicts that headless screw fixation is a better option if fragment thickness is over 15 mm in terms of the comparable peak failure load to suture anchor fixation (headless screw: 432.55 N (SD 62.25); suture anchor: 446.58 N (SD 84.97)), and less fracture fragment displacement after cyclic loading (headless screw: 3.94 N (SD 1.76); suture anchor: 8.68 N (SD 1.84)). Given that the fragment thickness is less than 10 mm, suture anchor fixation is a safer option.

Conclusion

Fracture fragment thickness helps in making the decision of either using headless screw or suture anchor fixation in treating calcaneal tuberosity avulsion fracture, based on the regression models of our study.

Bone quality in total shoulder arthroplasty: a prospective study correlating computed tomography Hounsfield units with thumb test and fracture risk assessment tool score

Background

To evaluate if Hounsfield units (HU) measured on preoperative computed tomography (CT) scans at the anatomic neck of the proximal humerus correlates with intraoperative findings of the "thumb test" in assessment of bone quality in shoulder arthroplasty patients.

Methods

Primary anatomic total shoulder and reverse total shoulder arthroplasty patients from 2019-2022 with an available preoperative CT scan of the operative shoulder were prospectively enrolled at a single center with 3 surgeons who perform shoulder arthroplasty. The "thumb test" was performed intraoperatively; a positive test signified "good bone." Demographic information, including prior dual x-ray absorptiometry scans, was extracted from the medical record. HU at the cut surface of the proximal humerus were calculated, as was cortical bone thickness on preoperative CT. Fracture risk assessment tool (FRAX) scores were calculated for 10-year risk of osteoporotic fracture.

Results

A total of 149 patients were enrolled. Mean age was 67.6 ± 8.5 years with 69 (46.3%) being males. Patients with a negative thumb test were significantly older (72.3 ± 6.6 vs. 66.5 ± 8.6 years; P < .001) than those with a positive thumb test. Males were more likely to have a positive thumb test than females (P = .014). Patients with a negative thumb test had significantly lower HUs on preoperative CT (16.3 ± 29.7 vs. 51.9 ± 35.2; P < .001). Patients with a negative thumb test had a higher mean FRAX score (14.1 ± 7.9 vs. 8.0 ± 4.8; P < .001). Receiver operator curve analysis was performed to identify a cut-off value for CT HU of 36.67, above which the thumb test is likely to be positive. Furthermore, receiver operator curve analysis also identified optimal cut-off values for 10-year risk of fracture by FRAX score of 7.75 HU, below which the thumb test is likely to be positive. Fifty patients were at high risk based on FRAX and HU; surgeons classified 21 (42%) as having "poor bone" quality through a negative thumb test. High-risk patients had a negative thumb test 33.8% (23/68) and 37.1% (26/71) of the time for HU and FRAX, respectively.

Conclusions

Surgeons are poor at identifying suboptimal bone quality at the anatomic neck of the proximal humerus based on intraoperative thumb test when referencing against CT HU and FRAX scores. The objective measures of CT HU and FRAX scoring may be useful metrics to incorporate into surgeons' preoperative plans for humeral stem fixation using readily available imaging and demographic data.

Reliability and validity of pose estimation algorithm for measurement of knee range of motion after total knee arthroplasty

We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland-Altman analyses to evaluate the agreement and error between radiography and the other measurements. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R² of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner's skills.

CT required to perform robotic-assisted total hip arthroplasty can identify previously undiagnosed osteoporosis and guide femoral fixation strategy

Osteoporosis can determine surgical strategy for total hip arthroplasty (THA), and perioperative fracture risk. The aims of this study were to use hip CT to measure femoral bone mineral density (BMD) using CT X-ray absorptiometry (CTXA), determine if systematic evaluation of preoperative femoral BMD with CTXA would improve identification of osteopenia and osteoporosis compared with available preoperative dual-energy X-ray absorptiometry (DXA) analysis, and determine if improved recognition of low BMD would affect the use of cemented stem fixation. Retrospective chart review of a single-surgeon database identified 78 patients with CTXA performed prior to robotic-assisted THA (raTHA) (Group 1). Group 1 was age- and sex-matched to 78 raTHAs that had a preoperative hip CT but did not have CTXA analysis (Group 2). Clinical demographics, femoral fixation method, CTXA, and DXA data were recorded. Demographic data were similar for both groups. Preoperative femoral BMD was available for 100% of Group 1 patients (CTXA) and 43.6% of Group 2 patients (DXA). CTXA analysis for all Group 1 patients preoperatively identified 13 osteopenic and eight osteoporotic patients for whom there were no available preoperative DXA data. Cemented stem fixation was used with higher frequency in Group 1 versus Group 2 (28.2% vs 14.3%, respectively; p = 0.030), and in all cases where osteoporosis was diagnosed, irrespective of technique (DXA or CTXA). Preoperative hip CT scans which are routinely obtained prior to raTHA can determine bone health, and thus guide femoral fixation strategy. Systematic preoperative evaluation with CTXA resulted in increased recognition of osteopenia and osteoporosis, and contributed to increased use of cemented femoral fixation compared with routine clinical care; in this small study, however, it did not impact short-term periprosthetic fracture risk.

Associations Among Hip Structure, Bone Mineral Density, and Strength Vary With External Bone Size in White Women

Bone mineral density (BMD) is heavily relied upon to reflect structural changes affecting hip strength and fracture risk. Strong correlations between BMD and strength are needed to provide confidence that structural changes are reflected in BMD and, in turn, strength. This study investigated how variation in bone structure gives rise to variation in BMD and strength and tested whether these associations differ with external bone size. Cadaveric proximal femurs (n = 30, White women, 36-89+ years) were imaged using nanocomputed tomography (nano-CT) and loaded in a sideways fall configuration to assess bone strength and brittleness. Bone voxels within the nano-CT images were projected onto a plane to create pseudo dual-energy X-ray absorptiometry (pseudo-DXA) images consistent with a clinical DXA scan. A validation study using 19 samples confirmed pseudo-DXA measures correlated significantly with those measured from a commercially available DXA system, including bone mineral content (BMC) (R ²  = 0.95), area (R ²  = 0.58), and BMD (R ²  = 0.92). BMD-strength associations were conducted using multivariate linear regression analyses with the samples divided into narrow and wide groups by pseudo-DXA area. Nearly 80% of the variation in strength was explained by age, body weight, and pseudo-DXA BMD for the narrow subgroup. Including additional structural or density distribution information in regression models only modestly improved the correlations. In contrast, age, body weight, and pseudo-DXA BMD explained only half of the variation in strength for the wide subgroup. Including bone density distribution or structural details did not improve the correlations, but including post-yield deflection (PYD), a measure of bone material brittleness, did increase the coefficient of determination to more than 70% for the wide subgroup. This outcome suggested material level effects play an important role in the strength of wide femoral necks. Thus, the associations among structure, BMD, and strength differed with external bone size, providing evidence that structure-function relationships may be improved by judiciously sorting study cohorts into subgroups. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.