Background:Total shoulder arthroplasty (TSA) has evolved as a treatment for advanced shoulder osteoarthrosis, with stemless implants gaining popularity due to reduced risks of stress shielding and complications associated with stemmed designs. However, the optimal technique for repairing the subscapularis with lesser tuberosity osteotomy (LTO) during TSA remains under investigation. This study evaluates the biomechanical performance of two repair techniques-bone tunneling and suture anchors-used for LTO in the context of stemless TSA. Methods:Ten shoulders from 6 cadaveric specimens (3 males and 3 females; aged 58-93 years old) were prepared and allocated to bone tunneling or suture anchor repair groups. Cyclic loading tests were performed, followed by incremental load-to-failure protocols. Outcomes included repair gapping during cyclic loading, initial repair stiffness (derived as the average secant stiffness for 10 of the initial 3,000 cycles prior to fatigue), cycles to failure, displacement of repair, and load to failure. Results:The mean age of the cadavers used in this study was 90.2 ± 14.7 years. Mean failure load were alike, and cycles to failure nearly identical, between groups (P = .86-1.00). No significant differences were observed between the two groups in repair gapping during cyclic loading (P = .42). However, a nonsignificant trend was observed for initial repair stiffness (P = .07), with the tunnel group showing greater stiffness (62.5 ± 13.9 N/mm) compared to the anchor group (46.0 ± 10.6 N/mm). A trend was also noted in displacement of repair (P = .099), with the tunnel group exhibiting greater displacement (41.4 ± 17.3 mm) than the anchor group (23.0 ± 13.1 mm). Conclusion:This study suggests that both techniques may yield comparable biomechanical outcomes in cadaveric models of LTO repair, which warrants further exploration. As a pilot project, this study lays the groundwork for future research that could expand upon these preliminary results and contribute to a deeper understanding of LTO repair techniques.

Background:Adjustment of femoral stem anteversion can be used to create a more stable hip to reduce the risk of dislocation in total hip arthroplasty. Depending on the amount of version, forces transmitted to the proximal femur may vary and alter the biomechanical behavior. The purpose of this study was to determine the effect of anteversion on the stiffness of the construct and femoral stem subsidence. Methods:A biomechanical study was performed using Sawbones composite femurs and a flat taper-wedge stem to assess loading and implant subsidence. Sawbones femurs were prepared with 0-, 15-, or 30 degrees of anteversion relative to the native femur version and tested in cyclic compression for 7200 cycles. Outcomes measured included stem size, initial stiffness, change in stiffness, final stiffness, and amount of subsidence. Results:Stem size decreased incrementally with the addition of anteversion. There was a statistical difference in subsidence between the constructs placed at 0-, 15-, and 30-degrees of anteversion (in mm, 0-degrees 0.778, 15-degrees 1.045, 30-degrees 0.648, p < 0.006). The construct with the femoral stem placed at 15° anteversion had lower initial stiffness, greater subsidence, and greater Δstiffness relative to the 0- and 30-degree constructs. Conclusion:Increasing femoral anteversion relative to the native anteversion leads to decreased stem size. Changing the stem anteversion relative to the native femoral anteversion affected the initial stiffness, final stiffness, change in stiffness, and subsidence; however, the differences may not be clinically different.

Vertebral fractures are the most common type of osteoporotic fracture and associated with significant complications. Timely intervention is important to prevent vertebral fractures, however the current standard for assessing osteoporosis (bone mineral density) is not fully accurate for identifying at-risk individuals. Inspired by a laboratory technique combining microcomputed tomography with mechanical loading for mechanical assessment of extracted bone structures, digital tomosynthesis-based digital volume correlation (DTS-DVC) uses supine and standing DTS images of patients in combination with DVC. The current study evaluated in vivo precision errors, and the utility of DTS-DVC in identifying mechanically compromised vertebrae. Seven patients with vertebral fracture (Fx) and twelve without (NFx) were DTS-imaged, and endplate-to-endplate displacement, stiffness, compliance, and endplate distribution statistics were calculated using supine reference images and images acquired in supine, standing, standing while holding added weight. The in vivo measurement error of DTS-DVC metrics and the extent to which DTS-DVC can measure differences in vertebrae due to loading and presence of vertebral deformity (vertebral fracture) were examined. Total measurement error was low (0.017-0.019 mm), and all measured parameters changed with loading (p < 0.0001 to p < 0.05). Endplate-to-endplate displacement and displacement heterogeneity were significantly higher in fractured vs adjacent intact vertebrae. There were large differences in DVC variables between intact L1 vertebrae of Fx and NFx groups; however, these were not statistically demonstrable. Collectively, results support the in vivo feasibility of DTS-DVC and warrant further investigation. A biomechanics-based assessment of vertebral bone quality is expected to improve our understanding and clinical assessment of vertebral fracture risk.

Vertebral fractures are a common and debilitating consequence of osteoporosis. Bone mineral density (BMD), measured by dual energy x-ray absorptiometry (DXA), is the clinical standard for assessing overall bone quantity but falls short in accurately predicting vertebral fracture. Fracture risk prediction may be improved by incorporating metrics of microstructural organization from an appropriate imaging modality. Digital tomosynthesis (DTS)-derived textural and microstructural parameters have been previously correlated to vertebral bone strength in vitro, but the in vivo utility has not been explored. Therefore, the current study sought to establish the extent to which DTS-derived measurements of vertebral microstructure and size discriminate patients with and without vertebral fracture. In a cohort of 93 postmenopausal women with or without history of vertebral fracture, DTS-derived microstructural parameters and vertebral width were calculated for T12 and L1 vertebrae, as well as lumbar spine BMD and trabecular bone score (TBS) from DXA images. Fracture patients had lower BMD and TBS, while DTS-derived degree of anisotropy and vertebral width were higher, compared to nonfracture (p < 0.02 to p < 0.003) patients. The addition of DTS-derived parameters (fractal dimension, lacunarity, degree of anisotropy and vertebral width) improved discriminative capability for models of fracture status (AUC = 0.79) compared to BMD alone (AUC = 0.67). For twelve additional participants who were imaged twice, in vivo repeatability errors for DTS parameters were low (0.2 % - 7.3 %). The current results support the complementary use of DTS imaging for assessing bone quality and improving the accuracy of fracture risk assessment beyond that achievable by DXA alone.

The zygapophyseal (facet) joint plays a critical role in load transmission and stability of the spine, and facet degeneration is a common consequence of aging and osteoarthritis. The ability to accurately measure facet space is important, as decreased facet space is associated with facet degeneration and lower back pain. Although grading systems exist for assessing facet joint space narrowing, static imaging fails to characterize changes in the facet gap under load that play a role in segmental stability. Current methods for estimating the dynamic behavior of the facet joint are either inaccurate, radiation costly, or clinically impractical. In the current study, we demonstrate the feasibility of a novel method for 3D measurement of facet joint space using digital tomosynthesis (DTS) imaging in supine and standing positions. Facet gap measurements were found to be strongly correlated with (r to 0.98) and accurate (<20 µm error for median facet gap) relative to microcomputed tomography reference values. In a pilot in vivo demonstration with seven participants, the effect of physiological loading was detectable, with median facet joint space being larger in standing as compared to supine images (p < 0.0001). The presented approach may be useful in directly characterizing changes in the facet joint relevant to segmental stability that are not readily assessed via current clinical imaging methods.

Adherence to osteoporosis screening guidelines could be considerably higher if offered at the time of routine mammography using the same imaging modality. We found that forearm density measurements using a breast imaging system provides density information with excellent diagnostic capability for osteoporosis and osteopenia status determined by hip and spine DXA. PURPOSE:Adherence to osteoporosis screening guidelines via bone mineral density (BMD) measurements with dual-energy x-ray absorptiometry (DXA) is low. Since adherence to breast cancer screening is quite high, it was suggested that the rate of osteoporosis screening can be improved if wrist imaging were performed at the time of breast screening using the very same equipment. METHODS:Digital wrist tomosynthesis (DWT) imaging was performed in 150 women using a 3D mammography system and BMD was measured from both 3D tomosynthesis and synthesized 2D images. In addition, standard DXA based BMD measurements were performed at the hip, spine, and forearm sites. We examined the extent to which DWT-derived ultradistal radius BMD correlates with DXA based BMD measurements, evaluated DWT measurement precision errors, and determined the accuracy of DWT in diagnosing low bone mass and osteoporosis in vivo. RESULTS:DWT BMD strongly correlated with DXA-derived ultradistal radius BMD (R2 up to 0.814) and discriminated osteoporosis (AUC up to 0.978) and osteopenia (AUC up to 0.938) by ultradistal T-score with low in vivo precision errors (0.91-2.3%). BMD derived from 3D DWT BMD performed comparably to forearm DXA BMD in the diagnosis of osteopenia (AUC up to 0.916) and osteoporosis (AUC up to 0.946) determined by hip and spine DXA. CONCLUSIONS:DWT can be readily implemented in mammography settings with similar diagnostic accuracy to DXA, has the potential to increase adherence to osteoporosis screening recommendations, and offers a convenient means to measure bone density within the highly accessible breast screening environment.

Bone fractures due to osteoporosis are a significant problem. Limited accuracy of standard bone mineral density (BMD) for fracture risk assessment, combined with low adherence to bone health screening precludes identification of those at risk of fracture. Because of the wide availability of digital breast tomosynthesis (DBT) imaging, bone screening using a DBT scanner at the time of breast screening has been proposed. Earlier studies have shown that BMD, microstructure, and stiffness of the distal radius can be calculated using digital tomosynthesis imaging of the wrist (DWT). However, strength and stress/strain parameters, which are more relevant to structural failure, and have the potential to enhance the utility of DWT, were not examined previously. Therefore, this study aimed to examine the ability of DWT to discriminate patients with and without fragility fracture using DWT based finite element (DWT-FE) derived strength and stress/strain distribution properties, and to determine in vivo repeatability of these biomechanical properties. Twenty-two postmenopausal women with any fragility fracture (included spine, hip, distal radius, humerus and tibia fractures) and 68 without were recruited. Each participant's nondominant arm (dominant arm if history of fracture in the nondominant arm) was scanned with DWT and compressive loading was simulated using FE modeling. Six additional patients were DWT-scanned thrice, with repositioning, to determine the repeatability of the study variables. Age and T-score were not different between fracture and nonfracture groups (p > 0.1), but strength and stress/strain parameters were significant predictors of fracture status (AUC = 0.64-0.74). Standard deviation of tensile strain was the most discriminatory variable for fracture status (AUC = 0.74) and was independent from stiffness. Repeatability error of DWT biomechanical properties was 0.7 % to 5.8 %. This study demonstrated that DWT-FE based strength and standard deviation of tensile strain were reproducible and predict fracture status independent from BMD and stiffness. The results suggest that the accuracy of fracture risk screening can be improved in the highly accessible environment of mammographic imaging.

Vertebral fractures are the most common osteoporotic fractures, but their prediction using standard bone mineral density (BMD) measurements from dual energy X-ray absorptiometry (DXA) is limited in accuracy. Stiffness, displacement, and strain distribution properties derived from digital tomosynthesis-based digital volume correlation (DTS-DVC) have been suggested as clinically measurable metrics of vertebral bone quality. However, the extent to which these properties correlate to vertebral strength is unknown. To establish this relationship, two independent experiments, one examining isolated T11 and the other examining L3 vertebrae within the L2-L4 segments from cadaveric donors were utilized. Following DXA and DTS imaging, the specimens were uniaxially compressed to fracture. BMD, bone mineral content (BMC), and bone area were recorded for the anteroposterior and lateromedial views from DXA, stiffness, endplate to endplate displacement and distribution statistics of intravertebral strains were calculated from DTS-DVC and vertebral strength was measured from mechanical tests. Regression models were used to examine the relationships of strength with the other variables. Correlations of BMD with vertebral strength varied between experimental groups (R-adj(2) = 0.19-0.78). DTS-DVC derived properties contributed to vertebral strength independently from BMD measures (increasing R-adj(2) to 0.64-0.95). DTS-DVC derived stiffness was the best single predictor (R-adj(2) = 0.66, p < 0.0001) and added the most to BMD in models of vertebral strength for pooled T11 and L3 specimens (R-adj(2) = 0.95, p < 0.0001). These findings provide biomechanical relevance to DTS-DVC calculated properties of vertebral bone and encourage further efforts in the development of the DTS-DVC approach as a clinical tool.

Despite effective therapies for those at risk of osteoporotic fracture, low adherence to screening guidelines and limited accuracy of bone mineral density (BMD) in predicting fracture risk preclude identification of those at risk. Because of high adherence to routine mammography, bone health screening at the time of mammography using a digital breast tomosynthesis (DBT) scanner has been suggested as a potential solution. BMD and bone microstructure can be measured from the wrist using a DBT scanner. However, the extent to which biomechanical variables can be derived from digital wrist tomosynthesis (DWT) has not been explored. Accordingly, we measured stiffness from a DWT based finite element (DWT-FE) model of the ultra-distal (UD) radius and ulna, and correlate these to reference microcomputed tomography image based FE (μCT-FE) from five cadaveric forearms. Further, this method is implemented to determine in vivo reproducibility of FE derived stiffness of UD radius and demonstrate the in vivo utility of DWT-FE in bone quality assessment by comparing two groups of postmenopausal women with and without a history of an osteoporotic fracture (Fx; n = 15, NFx; n = 51). Stiffness obtained from DWT and μCT had a strong correlation (R2 = 0.87, p < 0.001). In vivo repeatability error was <5 %. The NFx and Fx groups were not significantly different in DXA derived minimum T-scores (p > 0.3), but stiffness of the UD radius was lower for the Fx group (p < 0.007). Logistic regression models of fracture status with stiffness of the nondominant arm as the predictor were significant (p < 0.01). In conclusion this study demonstrates the feasibility of fracture risk assessment in mammography settings using DWT imaging and FE modeling in vivo. Using this approach, bone and breast screening can be performed in a single visit, with the potential to improve both the prevalence of bone health screening and the accuracy of fracture risk assessment.

The vertebral endplate and cortical shell play an important structural role and contribute to the overall strength of the vertebral body, are at highest risk of initial failure, and are involved in degenerative disease of the spine. The ability to accurately measure the thickness of these structures is therefore important, even if difficult due to relatively low resolution clinical imaging. We posit that digital tomosynthesis (DTS) may be a suitable imaging modality for measurement of endplate and cortical shell thickness owing to the ability to reconstruct multiplanar images with good spatial resolution at low radiation dose. In this study, for 25 cadaveric L1 vertebrae, average and standard deviation of endplate and cortical shell thickness were measured using images from DTS and microcomputed tomography (tiCT). For endplate thickness measurements, significant correlations between DTS and tiCT were found for all variables when comparing thicknesses measured in both the overall endplate volume (R-2 = 0.25-0.54) and when measurements were limited to a central range of coronal or sagittal slices (R-2 = 0.24-0.62). When compared to reference values from the overall shell volume, DTS thickness measurements were generally nonsignificant. However, when measurement of cortical shell thickness was limited to a range of central slices, DTS outcomes were significantly correlated with reference values for both sagittal and coronal central regions (R-2 = 0.21-0.49). DTS may therefore offer a means for measurement of endplate thickness and, within a limited sagittal or coronal measurement volume, for measurement of cortical shell thickness.

Creep deformation of human vertebrae accumulates under physiological levels of load and is understood to contribute to the progression toward clinically observable vertebral fracture. However, little information is available in terms of clinically measurable predictors of creep behavior in human vertebrae. In this study, creep tests were performed on 22 human cadaveric T12 vertebrae (13 male, 9 female; age 41-90). Areal and volumetric bone density parameters were measured from the same specimens using dual x-ray absorptiometry and high resolution computed tomography. Image textural analyses (which probe the organization of image intensities within the cancellous bone in low resolution clinical imaging) were performed using digital tomosynthesis (DTS) images. Multiple regression models were constructed to examine the relationship between creep properties and bone density and DTS image textural parameters. For the standard clinical imaging configuration, models including DTS derived image textural parameters alone were generally more explanatory (adjusted R2: 0.14-0.68) than those with bone density parameters forced in the models (adjusted R2: 0.17-0.61). Metrics of textural heterogeneity and anisotropy presented as the most explanatory imaging markers for creep deformation and recovery from creep. These metrics of image texture may help provide, independent from bone mass, important clinically measurable indicators of the time dependent deformation of human vertebrae.

Lumbar 1 vertebrae are among those most commonly fracture due to osteoporosis. The strength of human vertebrae and its structural, microstructural and material determinants have been the subject of numerous studies. However, a comprehensive evaluation of properties beyond maximum load to fracture has not been available for the L1 vertebrae. The objective of this study was to document these properties in association with each other and with the geometric, density and cancellous and cortical structure properties for human L1 vertebrae. Bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), connectivity density (Conn.Dn), degree of anisotropy (DA), structure model index (SMI) and fractal dimension (FD) of the cancellous microstructure, tissue mineral density (TMD), and thickness of the cortical shell (Sh.Th) and superior and inferior endplates thicknesses (EP.Th.S and EP.Th.I) were measured using microcomputed tomography for 27 cadaveric L1 vertebrae. Volumetric cancellous, shell and integral bone mineral densities (vBMD, shBMD and iBMD) as well as vertebral volume (V), height and width were measured using high resolution CT. Areal whole vertebral body and regional BMDs were measured using dual energy x-ray absorptiometry (DXA) in coronal and lateral views. Specimens were then uniaxially compressed to 15% of their height to obtain vertebral stiffness (K) and strength (Fmax) as well as displacement (D), force (F) and energy (W) properties at characteristic points of the load-displacement curve including yield (y), fracture (f), compaction (c), final displacement (t) and residual after unload (r). Correlation and principal component analyses suggested displacements to failure (Df), collapse (Dc) and recovery (Dr) contain information distinct from strength and stiffness. Bone size (V) was present, independently, in multiple regression models of K, Fy, Wy, Fmax, Df, Wt, Wfc and Dr (p < 0.05 to p < 0.0001), areal BMD in models of Dy, Wy, Fmax, Wf, Fc, Wt, Wyf and Wct (p < 0.04 to p < 0.0001), Sh.Th in models of Df, Fc and εr (p < 0.02 to p < 0.002), EP.Th.S in models of Fc and Wct (p < 0.004 to p < 0.0006), EP.Th.I in the model of Wct (p < 0.02), FD in models of Fy, Dy and Fmax (p < 0.03 to p < 0.004), Tb.Sp in models of K and Dy (p < 0.002 to p < 0.0004), Conn.Dn in the model of Df (p < 0.0009), and SMI in the model of Wt (p < 0.02). R2adj varied from 0.12 (Dr) to 0.80 (Wt) for the multiple regression models for all significant variables. In conclusion, there is distinct information in forces and displacements associated with characteristic events occurring during uniaxial compression and recovery, specifically in displacements associated with compaction and recovery. Though there are common factors such as bone mass for some, distinct cancellous and cortical features likely contribute to these events in L1. The descriptive data reported here are expected to provide reference values for comparative and model building efforts, and the relationships found are expected to provide insight into mechanical functions of an L1 vertebra.

Background: Arthroplasty with artificial disc replacement for surgical treatment of cervical spine degeneration was introduced with the notion that motion-preserving approaches would prevent development of adjacent segment disease. Though clinical outcomes favor arthroplasty over the commonly used anterior cervical discectomy with fusion approach, clinical studies confirming the biomechanical basis of these results are lacking. The aim of this study was to compare intervertebral kinematics between arthroplasty and fusion patients 6.5 years post-surgery during physiological motion of the neck. Methods: Using a biplane dynamic X-ray system, computed tomography imaging and model based tracking algorithms, three dimensional intervertebral kinematics were measured during neck axial rotation and extension in 14 patients treated for cervical radiculopathy with fusion (n = 8) or arthroplasty (n = 6). The measurements were performed at 2-year (baseline) and 6.5 year post-surgical time points, with the main interest being in the interaction between surgery types and time points. 3 translations and 3 rotations were investigated for the index (C5C6), and upper-(C4C5) and lower adjacent levels (C6C7). Findings: Surgery-time interaction was significant for axial rotation (P < 0.04) and flexion-extension rotation (P < 0.005) in C4C5 during neck axial rotation, left-right translation (P < 0.04) in C5C6 and anterior-posterior translation in C6C7 (P < 0.04) during neck extension. In contrast with the expectations, axial rotation and flexion-extension decreased in C4C5 during neck rotation and anterior-posterior translation decreased in C6C7 during neck extension for fusion. Interpretation: The findings do not support the notion that adjacent segment motion increases after fusion.

Vertebral fractures are the most common osteoporotic fractures, but clinical means for assessment of vertebral bone integrity are limited in accuracy, as they typically use surrogate measures that are indirectly related to mechanics. The objective of this study was to examine the extent to which intravertebral strain distributions and changes in cancellous bone texture generated by a load of physiological magnitude can be characterized using a clinically available imaging modality. We hypothesized that digital tomosynthesis-based digital volume correlation (DTS-DVC) and image texture-based metrics of cancellous bone microstructure can detect development of mechanical strains under load. Isolated cadaveric T11 vertebrae and L2-L4 vertebral segments were DTS imaged in a nonloaded state and under physiological load levels. Axial strain, maximum principal strain, maximum compressive and tensile principal strains, and von Mises equivalent strain were calculated using the DVC technique. The change in textural parameters (line fraction deviation, anisotropy, and fractal parameters) under load was calculated within the cancellous centrum. The effect of load on measured strains and texture variables was tested using mixed model analysis of variance, and relationships of strain and texture variables with donor age, bone density parameters, and bone size were examined using regression models. Magnitudes and heterogeneity of intravertebral strain measures correlated with applied loading and were significantly different from background noise. Image texture parameters were found to change with applied loading, but these changes were not observed in the second experiment testing L2-L4 segments. DTS-DVC-derived strains correlated with age more strongly than did bone mineral density (BMD) for T11.

Digital tomosynthesis (DTS) is a clinically available modality that allows imaging of a patient's spine in supine and standing positions. The purpose of this study was to establish the extent to which vertebral displacement and stiffness derived from DTS-based digital volume correlation (DTS-DVC) are correlated with those from a reference method, i.e., microcomputed tomography-based DVC (μCT-DVC). T11 vertebral bodies from 11 cadaveric donors were DTS imaged twice in a nonloaded state and once under a fixed load level approximating upper body weight. The same vertebrae were µCT imaged in nonloaded and loaded states (40 μm voxel size). Vertebral displacements were calculated at each voxel using DVC with pairs of nonloaded and loaded images, from which endplate-to-endplate axial displacement (DDVC) and vertebral stiffness (SDVC) were calculated. Both DDVC and SDVC demonstrated strong positive correlations between DTS-DVC and μCT-DVC, with correlations being stronger when vertebral displacement was calculated using the median (R2=0.80; p<0.0002 and R2=0.93; p<0.0001, respectively) rather than average displacement (R2=0.63; p<0.004 and R2=0.69; p<0.002, respectively). In conclusion, the demonstrated relationship of DTS-DVC with the μCT standard supports further development of a biomechanics-based clinical assessment of vertebral bone quality using the DTS-DVC technique.

OBJECTIVE:To compare changes in foraminal motion at two time points post-surgery between artificial disc replacement (ADR) and anterior cervical discectomy and fusion (ACDF). METHODS:Eight ACDF and 6 ADR patients (all single-level C5-6) were tested at 2 years (T1) and 6.5 years (T2) post-surgery. The minimum foraminal height (FH.Min) and width (FW.Min) achieved during neck axial rotation and extension, and the range of these dimensions during motion (FH.Rn and FW.Rn, respectively) were measured using a biplane dynamic x-ray system, CT imaging and model-based tracking while patients performed neck axial rotation and extension tasks. Two-way mixed ANOVA was employed for analysis. RESULTS:In neck extension, significant interactions were found between year post-surgery and type of surgery for FW.Rn at C5-6 (p<0.006) and C6-7 (p<0.005), and for FH.Rn at C6-7 (p<0.01). Post-hoc analysis indicated decreases over time in FW.Rn for ACDF (p<0.01) and increases in FH.Rn for ADR (p<0.03) at the C6-7 adjacent level. At index level, FW.Rn was comparable between ACDF and ADR at T1, but was smaller for ACDF than for ADR at T2 (p<0.002). In axial rotation, differences were found between T1 and T2 but did not depend on type of surgery (p>0.7). CONCLUSIONS:Changes were observed in the range of foraminal geometry at adjacent levels from 2 years to 6.5 years post-surgery that were different between ACDF and ADR for neck extension. These changes are contrary to the notion that motion at adjacent levels continue to increase following ACDF as compared to ADR over the long term.

Background Post-surgical changes in adjacent segment motion are considered a factor in further development of degeneration and cervical radiculopathy. The objective was to examine the extent of correlations between physiological motion of cervical foramina and long-term patient reported outcomes (PRO). Methods Biplane X-ray imaging and CT-based markerless tracking were used to measure 3D static and dynamic dimensions during neck axial rotation and extension from 18 patients treated for C5-6 radiculopathy with fusion or arthroplasty. Minimum foraminal height (FH.Min) and width (FW.Min), and their range (FH.Range and FW.Range) achieved during a motion task were calculated for adjacent levels (C4-5 and C6-7) at 2.0±0.6 years post-surgery. The modified Japanese Orthopedic Association score (mJOAS), the Neck Disability Index (NDI) including the visual analogue scale (VAS) for neck and arm pain, and the EuroQol EQ-5D score were recorded at 6.5±1.1 years post-surgery. The relationships between 6.5-year outcomes and 2-year foraminal motion were examined using regression. Results Worsening patient-reported outcomes were generally associated with lower values of FW.Min (P<0.05 to P<0.008), the associations being stronger for neck extension (r2 up to 0.43). Dynamic foraminal measurements from the C6-7 level more significantly and consistently correlated with mJOAS, EQ-5D and NDI Arm Pain VAS (r2=0.27 to 0.43; P<0.03 to P<0.008), whereas those from the C4-5 level correlated with NDI Neck Pain VAS (r2=0.33; P<0.02). Conclusions Dynamic 3D foraminal dimensions at 2-year post-surgery, notably FW.Min measured in neck extension at adjacent levels, were associated with PRO at 6.5 years post-surgery. These relationships provide insight into the motion related factors in development of pain and loss of function, and may help develop markers or objective outcome measures.

Bone fractures attributable to osteoporosis are a significant problem. Though preventative treatment options are available for individuals who are at risk of a fracture, a substantial number of these individuals are not identified due to lack of adherence to bone screening recommendations. The issue is further complicated as standard diagnosis of osteoporosis is based on bone mineral density (BMD) derived from dual energy x-ray absorptiometry (DXA), which, while helpful in identifying many at risk, is limited in fully predicting risk of fracture. It is reasonable to expect that bone screening would become more prevalent and efficacious if offered in coordination with digital breast tomosynthesis (DBT) exams, provided that osteoporosis can be assessed using a DBT modality. Therefore, the objective of the current study was to explore the feasibility of using digital tomosynthesis imaging in a mammography setting. To this end, we measured density, cortical thickness and microstructural properties of the wrist bone, correlated these to reference measurements from microcomputed tomography and DXA, demonstrated the application in vivo in a small group of participants, and determined the repeatability of the measurements. We found that measurements from digital wrist tomosynthesis (DWT) imaging with a DBT scanner were highly repeatable ex vivo (error = 0.05%-9.62%) and in vivo (error = 0.06%-10.2%). In ex vivo trials, DWT derived BMDs were strongly correlated with reference measurements (R = 0.841-0.980), as were cortical thickness measured at lateral and medial cortices (R = 0.991 and R = 0.959, respectively) and the majority of micro structural measures (R = 0.736-0.991). The measurements were quick and tolerated by human patients with no discomfort, and appeared to be different between young and old participants in a preliminary comparison. In conclusion, DWT is feasible in a mammography setting, and informative on bone mass, cortical thickness, and microstructural qualities that are known to deteriorate in osteoporosis. To our knowledge, this study represents the first application of DBT for imaging bone. Future clinical studies are needed to further establish the efficacy for diagnosing osteoporosis and predicting risk of fragility fracture using DWT.