Intact Specimen Research Articles

Biomechanical Analysis of Range of Motion and Failure Characteristics of Osteoporotic Spinal Compression Fractures in Human Cadaver.

Background:Vertebroplasty is a treatment for osteoporotic vertebral compression fractures. The optimal location of needle placement for cement injection remains a topic of debate. As such, the authors assessed the effects of location of two types of cement instillations. In addition, the motion and failure modes at the index and adjacent segments were measured.Materials and Methods:Seven human osteoporotic cadaver spines (T1-L4), cut into four consecutive vertebral segments, were utilized. Of these, following the exclusion of four specimens not suitable to utilize for analysis, a total of 24 specimens were evaluable. Segments were randomly assigned into four treatment groups: unipedicular and bipedicular injections into the superior quartile or the anatomic center of the vertebra using confidence (Confidence Spinal Cement System®, DePuy Spine, Raynham, MA, USA) or polymethyl methacrylate. The specimens were subjected to nondestructive pure moments of 5 Nm, in 2.5 Nm increments, using pulleys and weights to simulate six degrees of physiological motion. A follower preload of 200 N was applied in flexion extension. Testing sequence: range of motion (ROM) of intact specimen, fracture creation, cement injection, ROM after cement, and compression testing until failure. Nonconstrained motion was measured at the index and adjacent levels.Results:At the index level, no significant differences were observed in ROM in all treatment groups (P > 0.05). There was a significant increase in adjacent level motion only for the treatment group that received a unipedicular cement injection at the anatomic center.Conclusion:The location of the needle (superior or central) and treatment type (unipedicular or bipedicular) had no significant effect on the ROM at the index site. At the adjacent levels, a significant increase occurred with therapy through a unipedicular approach into the centrum of the vertebra at the treated segment.

Retrofitting Notch Damaged Box Steel Beams with Composite Materials

An experimental program was designed to investigate the structural behavior of retrofitted notch damaged box steel beams using Fiber - Reinforced Polymer (FRP) under flexure up to failure. The experimental program included twelve box steel specimens; one intact specimen, one notched specimen and ten notches damaged specimen and repaired with FRP sheets. All the tested beams have 1000 mm length. The notches specimens were notched at the tension flanges at 400 mm distance from the beam edge to simulate a localized and non-uniformly distributed deterioration along the beam length. The beams were repaired by bonding the FRP to the tension flange only, and the sheets were wrapped to cover a part of the two webs for the two beam halves or for the half of the beam that includes the notch with different heights. All the tested beams were simulated using a Finite Element (FE) program, and the FE model gives good results in comparison with the test results. The presented results indicate that wrapping CFRP sheet around the two webs for the half of the beam that includes the notch only gives an acceptable structural performance in comparing with wrapping CFRP sheet around the two webs for two halves of the beam and in this beam, the difference in the deflections of the two halves of the beam at the ultimate load does not increase than 3.2%.

91 - Vaginal Extraction Index: A Predictive Model for Extraction of Hysterectomy Specimens

Study Objective: To determine the “Vaginal Extraction Index” as a predictive model for vaginal extraction that could assist gynecologic surgeons in preoperatively determining the likelihood of success in delivering an intact uterine specimen through the vagina following laparoscopic hysterectomy.

Is CFL Repair Necessary During Lateral Ankle Ligament Stabilization? A Biomechanical Comparison of Repair Techniques

There was a greater increase in stiffness following combined ATFL and CFL repair compared to ATFL repair alone. The intact stiffness of the ankle is highly predictive of repair stiffness and load to failure. Restoring CFL plays a relevant role in lateral ligament repair, however sufficient time for ligament healing should be allowed before inversion stresses are applied. Lateral ankle sprain is a common athletic injury. At least 20% of patients with severe ankle sprains will develop chronic ankle instability, and possibly require surgical repair. The most common mechanism of injury in ankle sprain is ankle inversion with a plantar flexed foot. The ATFL is injured most frequently, and higher grade injuries result in rupture to the CFL as well. The standard for lateral ligament stabilization is direct repair of the ATFL by open or arthroscopic technique. However, implications and necessity of repairing the CFL are not well understood. The purpose of this study was to assess the impact of repairing the ATFL alone compared to repairing both the ATFL and CFL, in a biomechanical cadaver model. We hypothesized that repairing the CFL will add significant ankle and subtalar joint stability during weight-bearing ankle inversion compared to ATFL repair alone. Ten matched pairs of fresh frozen human cadaveric ankles were dissected to expose intact ATFL and CFL. Ankles were mounted to an Instron at 20° plantar flexion and 15° of internal rotation. Each ankle was loaded to body weight and then inverted from 0 to 20° for three cycles; torque was recorded and stiffness was calculated. Ankles then underwent sectioning of ATFL and CFL and were randomly assigned to ATFL only repair using two arthroscopic Broström all-soft anchors, or combined ATFL and CFL repair. Testing was repeated after repair to 20° of inversion, then load-to-failure (LTF). The predominant mode of failure (17/20) after repair was at the ligament/suture interface – there were no occurrences of anchor pull-out. There was an 11.7% increase in stiffness in combined repairs, and only a 1.6% increase in single repairs, compared to the complete injury condition, although this did not reach statistical significance (p=.158). The CFL failed at lower torque (p=.017) and rotation (p=.01) than the ATFL in combined repairs. However, there was no difference between groups in inversion degrees or torque at failure of the ATFL during LTF. There was a strong correlation (r=.74) with intact stiffness and stiffness after repair, across both groups, and a strong correlation (r=.77) with intact stiffness and ATFL torque in LTF testing, across both groups. In a biomechanical weight-bearing inversion model, we found a greater increase in stiffness following combined ATFL and CFL repair compared to ATFL repair alone, although this did not reach statistical significance. This added stability is likely due to complimentary contributions of the CFL, not augmented strength of the ATFL, since ATFL rotation and torque at LTF were unaffected by CFL repair. Intact specimen stiffness correlated strongly with both stiffness after repair, and LTF torque of ATFL. Thus, a patient’s inherent laxity or stiffness is likely a meaningful contributor to strength after repair. The CFL fails before the ATFL, potentially indicating its vulnerability immediately following repair. Restoring the CFL likely plays a relevant role in lateral ligament repair, however sufficient time for ligament healing should be allowed before inversion stresses are applied.

Putting POP-Q to the test: does C-D=cervical length?

We investigated the correlation between calculated cervical length (CCL) and gross specimen cervical length (GCL) after total vaginal hysterectomy (TVH) at the time of surgery for pelvic organ prolapse (POP). This was a retrospective chart review of patients who had undergone TVH with reconstructive surgery for POP between 2013 and 2015. Patients without an intact specimen or documented cervical length in the pathology report were excluded. CCL was defined as the absolute difference between Pelvic Organ Prolapse Quantification (POP-Q) points C and D. GCL was obtained from the pathology report as the distance from the external to the internal os. The Bland-Altman method was used to assess the accuracy of POP-Q measurements with a priori ranges. Symptom severity was evaluated using the PFDI-20 questionnaire. Analysis of variance was used to model both GCL and CCL as a function of prolapse stage and the leading compartment. The final analysis included 202 subjects. Of the CCL measurements, 56.93% were within ±2cm of GCL, while 36.14% were within ±1cm. POP stage was significantly associated with GCL (P<0.0024). CCL was significantly longer in patients with stage 4 POP (3.57cm, 95% CI 3.13-4.00) than in those with stage 2 POP (P<0.0017; mean 2.68cm, 95% CI 2.45-2.92) and stage 3 POP (P<0.0300; mean 2.94cm, 95% CI 2.73-3.15). There were no significant correlations between PFDI scores and CCL or GCL. The agreement between POP-Q CCL (|C-D|) and GCL decreases with increasing POP-Q stage. There was no correlation between POP symptom severity and GCL or CCL. GCL significantly increased with increasing POP stage.

ATFL repair alone versus combined repairs of ATFL and CFL

Category: Ankle Introduction/Purpose: The standard for lateral ligament stabilization is direct repair of the ATFL by open or arthroscopic technique. The implications and necessity of repairing the CFL are not well understood. The purpose of this study was to assess the impact of repairing the ATFL alone compared to repairing both the ATFL and CFL, in a biomechanical cadaver model. We hypothesized that repairing the CFL will substantially augment ankle and subtalar joint stability during weight-bearing ankle inversion compared to ATFL repair alone. Methods: Ten matched pairs of fresh frozen human cadaveric ankles were dissected to expose intact ATFL and CFL. Ankles were mounted to an Instron at 20° plantar flexion and 15° of internal rotation. Each ankle was loaded to body weight and then tested from 0 to 20° of inversion for three cycles; stiffness and torque were recorded, peak pressure and contact area were recorded using a calibrated Tekscan sensor system, and rotational displacement of the talus and calcaneus relative to the ankle mortise was recorded using a three-dimensional motion capture system. Ankles then underwent sectioning of ATFL and CFL and were randomly assigned to ATFL only repair using two arthroscopic Broström all-soft anchors, or combined ATFL and CFL repair. Testing was repeated after repair to 20° of inversion, then load-to-failure (LTF). Results: The predominant mode of failure after repair was at the tissue/suture. There were no instances of anchor pullout. There was an 11.7% increase in stiffness in combined repairs, and only a 1.6% increase in ATFL-only repairs. CFL failed at lower torque and rotation than the ATFL in combined repairs. There were strong correlations between intact stiffness and stiffness after repair (r=.74) and ATFL torque in LTF testing (r=.77), across both groups. There was no significant difference in peak pressure or contact area in the tibiotalar joint between the intact ankle and ATFL or combined repair. Conclusion: We found a greater increase in stiffness following combined ATFL and CFL repair compared to ATFL repair alone. This added stability is due to complimentary contributions of the CFL, not augmented LTF strength of the ATFL. Intact specimen stiffness correlated strongly with stiffness after repair and LTF torque, suggesting that a patient’s inherent tissue laxity or inelasticity is likely a meaningful predictor of strength after repair. Restoring the CFL plays a relevant role in lateral ligament repair, however sufficient time for ligament healing should be allowed before substantial inversion stresses are applied.

Stepwise resection of the posterior ligamentous complex for stability of a thoracolumbar compression fracture: An in vitro biomechanical investigation.

To quantify the mechanical contribution of posterior ligamentous structures to the stability of thoracolumbar compression fractures.Twelve fresh human T11–L3 spinal specimens were harvested in this study. The 1/3 L1 vertebral body was resected in a wedged shape. After the preinjury had been created, the specimens were subjected to flexion–compression to create a fracture model. Resection of the ligaments was performed in a sequential manner from the bilateral facet capsule ligament (FCL), interspinous ligament, and supraspinous ligament (SSL) to the ligamentum flavum at the T12–L1 level. Then, for the intact specimen, fracture model, and ligament disruption steps, the range of motion (ROM) and neutral zone (NZ) of T12–L1 and L1–L2 were collected for each simulated movement.Sequential transection of the posterior ligamentous complex (PLC), ROM, and NZ were increased in all movements at the T12–L1 segment. In the flexion–extension (FE), the ROM and NZ demonstrated significant increases after the fracture model and resection of SSL and LF. In lateral bending (LB), the ROM increased after the fracture and removal of the LF, while the NZ showed a slight increase. In axial rotation, the fracture model and removal of the LF resulted in a significant increase in the ROM, and the NZ showed a slight change after step reduction. For the L1–L2 segment, resection of the FCL led to an increased ROM in LB.With rupture of SSL or LF, the stability of the segment decreased significantly compared with the intact and fracture model, particularly in FE motion, the function of the PLC was considered to be incompetent.

Coronoid reconstruction using osteochondral grafts: a biomechanical study

The purposes of this study were to test the hypothesis that coronoid deficiency in the setting of posteromedial rotatory instability (PMRI) must be reconstructed to restore articular contact pressures to normal and to compare 3 different osteochondral grafts for this purpose. After creation of a anteromedial fracture, six cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and to passively flex the elbow. Mean articular surface contact pressure data were collected and processed using TekScan sensors and software. After testing of the intact specimen (intact condition), a PMRI injury was created (PMRI condition). Testing was repeated after reconstruction of the lateral collateral ligament (LCL) (LCL-only condition), followed by reconstruction of the coronoid with 3 different osteochondral graft techniques (reconstructed conditions). Contact pressure was consistently significantly higher in the PMRI elbow compared with the intact, LCL-only, and reconstructed conditions (P < .006). The LCL-only elbow contact pressure was significantly higher than that of the intact and reconstructed conditions from 5° to 55° of flexion (P = .018). The contact pressure of the intact elbow was never significantly different from that of the reconstructed elbow, except at 5° of flexion (P ≤ .008). No significant difference was detected between each of the reconstructed techniques (P ≥ .15). However, the annular surface of the radial head was the only graft that yielded contact pressures not significantly different from normal at any flexion angle. Isolated reconstruction of the LCL did not restore native articular surface contact pressure, and reconstruction of the coronoid using osteochondral graft was necessary. There was no difference in contact pressures among the 3 coronoid reconstruction techniques.

Role of the lateral collateral ligament in posteromedial rotatory instability of the elbow

Posteromedial rotatory instability (PMRI) of the elbow consists of an anteromedial coronoid fracture with lateral collateral ligament (LCL) and posterior bundle of the medial collateral ligament (PMCL) tears. We hypothesized that the LCL tear is required for elbow subluxation/joint incongruity and that an elbow affected by an anteromedial subtype 2 coronoid fracture and a PMCL tear exhibits contact pressures different from both an intact elbow and an elbow affected by PMRI. Six cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and to passively flex the elbow from 0° to 90° and measure joint contact pressures. After testing of the intact specimen (INTACT-elbow), an anteromedial subtype 2 coronoid fracture with a PMCL tear (COR+PMCL-elbow) and a PMRI injury (PMRI-elbow), after adding an LCL tear, were tested. The highest values of mean contact pressure were used for the comparison among the 3 groups. Neither subluxation nor joint incongruity was observed in the COR+PMCL-elbow. The addition of an LCL detachment consistently caused subluxation and joint incongruity. Mean contact pressures were higher in the COR+PMCL-elbow compared with the INTACT-elbow (P < .03) but lower than in the PMRI-elbow (P < .001). The LCL lesion in PMRI is necessary for elbow subluxation and causes marked elevations in contact pressures. Even without subluxation, the COR+PMCL-elbow showed higher contact pressures compared with the INTACT-elbow. Treatment of PMRI should be directed toward prevention of joint incongruity, whether by surgical or nonsurgical means, to prevent high articular contact pressures.

Influence of Spinal Manipulative Therapy Force Magnitude and Application Site on Spinal Tissue Loading: A Biomechanical Robotic Serial Dissection Study in Porcine Motion Segments

ObjectiveIn order to define the relation between spinal manipulative therapy (SMT) input parameters and the distribution of load within spinal tissues, the aim of this study was to determine the influence of force magnitude and application site when SMT is applied to cadaveric spines. MethodsIn 10 porcine cadavers, a servo-controlled linear actuator motor provided a standardized SMT simulation using 3 different force magnitudes (100N, 300N, and 500N) to 2 different cutaneous locations: L3/L4 facet joint (FJ), and L4 transverse processes (TVP). Vertebral kinematics were tracked optically using indwelling bone pins, the motion segment removed and mounted in a parallel robot equipped with a 6-axis load cell. The kinematics of each SMT application were replicated robotically. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues. Forces experienced by the L3/L4 segment and spinal structures during SMT replication were recorded and analyzed. ResultsSpinal manipulative therapy force magnitude and application site parameters influenced spinal tissues loading. A significant main effect (P < .05) of force magnitude was observed on the loads experienced by the intact specimen and supra- and interspinous ligaments. The main effect of application site was also significant (P < .05), influencing the loading of the intact specimen and facet joints, capsules, and ligamentum flavum (P < .05). ConclusionSpinal manipulative therapy input parameters of force magnitude and application site significantly influence the distribution of forces within spinal tissues. By controlling these SMT parameters, clinical outcomes may potentially be manipulated.

Association of Coloproctology of Great Britain & Ireland (ACPGBI): Guidelines for the Management of Cancer of the Colon, Rectum and Anus (2017) - Pathology Standards and Datasets.

Association of Coloproctology of Great Britain & Ireland (ACPGBI): Guidelines for the Management of Cancer of the Colon, Rectum and Anus (2017) - Pathology Standards and Datasets.

Strength failure behavior of granite containing two holes under Brazilian test

A series of Brazilian tests under diameter compression for disc specimens was carried out to investigate the strength and failure behavior by using acoustic emission (AE) and photography monitoring technique. On the basis of experimental results, load-displacement curves, AE counts, real-time crack evolution process, failure modes and strength property of granite specimens containing two pre-existing holes were analyzed in detail. Two typical types of load-displacement curves are identified, i.e., sudden instability (type I) and progressive failure (type II). In accordance with the two types of load-displacement curves, the AE events also have different responses. The present experiments on disc specimens containing two pre-existing holes under Brazilian test reveal four distinct failure modes, including diametrical splitting failure mode (mode I), one crack coalescence failure mode (mode II), two crack coalescences failure mode (mode III) and no crack coalescence failure mode (mode IV). Compared with intact granite specimen, the disc specimen containing two holes fails with lower strength, which is closely related to the bridge angle. The failure strength of pre-holed specimen first decreases and then increases with the bridge angle. Finally, a preliminary interpretation was proposed to explain the strength evolution law of granite specimen containing two holes based on the microscopic observation of fracture plane.

Arthroscopic Brostrom versus combined repairs of ATFL and CFL: A Biomechanical Comparison of Repair Techniques

The standard for lateral ligament stabilization is direct repair of the ATFL by open or arthroscopic technique. The implications and necessity of repairing the CFL are not well understood. The purpose of this study was to assess the impact of repairing the ATFL alone compared to repairing both the ATFL and CFL, in a biomechanical cadaver model. We hypothesized that repairing the CFL will substantially augment ankle and subtalar joint stability during weight-bearing ankle inversion compared to ATFL repair alone. Ten matched pair fresh frozen human cadaveric ankles were mounted to an Instron, loaded to body weight and inverted to 20° for three cycles; torque and stiffness were recorded. Ankles underwent sectioning of ATFL and CFL and were randomly assigned to ATFL only repair using two arthroscopic Broström all-soft anchors, or combined ATFL and CFL repair. Testing was repeated after repair, followed by load-to-failure (LTF). The predominant mode of failure after repair was at the tissue/suture. There was an 11.7% increase in stiffness in combined repairs, and only a 1.6% increase in ATFL-only repairs. CFL failed at lower torque and rotation than the ATFL in combined repairs. There were strong correlations between intact stiffness and stiffness after repair (r=.74) and ATFL torque in LTF testing (r=.77), across both groups. We found a greater increase in stiffness following combined ATFL and CFL repair compared to ATFL repair alone. This added stability is due to complimentary contributions of the CFL, not augmented LTF strength of the ATFL. Intact specimen stiffness correlated strongly with stiffness after repair and LTF torque, suggesting that a patient's inherent tissue laxity or inelasticity is likely a meaningful predictor of strength after repair. Restoring the CFL plays a relevant role in lateral ligament repair, however sufficient time for ligament healing should be allowed before inversion stresses are applied.

Biomechanical Stability of a Stand-Alone Interbody Spacer in Two-Level and Hybrid Cervical Fusion Constructs.

Study Design:In vitro human cadaveric biomechanical analysis.Objective:To evaluate the segmental stability of a stand-alone spacer (SAS) device compared with the traditional anterior cervical plate (ACP) construct in the setting of a 2-level cervical fusion construct or as a hybrid construct adjacent to a previous 1-level ACP construct.Methods:Twelve human cadaveric cervical spines (C2-T1) were nondestructively tested with a custom 6-degree-of-freedom spine simulator under axial rotation (AR), flexion-extension (FE), and lateral bending (LB) at 1.5 N m loads. After intact analysis, each specimen underwent instrumentation and testing in the following 3 configurations, with each specimen randomized to the order of construct: (A) C5-7 SAS; (B) C5-6 ACP, and C6-7 SAS (hybrid); (C) C5-7 ACP. Full range of motion (ROM) data at C5-C7 was obtained and analyzed by each loading modality utilizing mean comparisons with repeated measures analysis of variance with Sidak correction for multiple comparisons.Results:Compared with the intact specimen, all tested constructs had significantly increased segmental stability at C5-C7 in AR and FE ROM, with no difference in LB ROM. At C5-C6, all test constructs again had increased segmental stability in FE ROM compared with intact (10.9° ± 4.4° Intact vs SAS 6.6° ± 3.2°, P < .001; vs.Hybrid 2.9° ± 2.0°, P = .005; vs ACP 2.1° ± 1.4°, P < .001), but had no difference in AR and LB ROM. Analysis of C6-C7 ROM demonstrated all test groups had significantly greater segmental stability in FE ROM compared with intact (9.6° ± 2.7° Intact vs SAS 5.0° ± 3.0°, P = .018; vs Hybrid 5.0° ± 2.7°, P = .018; vs ACP 4.4° ± 5.2°, P = .005). Only the hybrid and 2-level ACP constructs had increased stability at C6-C7 in AR ROM compared with intact, with no difference for all test groups in LB ROM. Comparison between test constructs demonstrated no difference in C5-C7 and C6-C7 segmental stability in all planes of motion. However, at C5-C6 comparison between test constructs found the 2-level SAS had significantly less segmental stability compared to the hybrid (6.6° ± 3.2° vs 2.9° ± 2.0°, P = .025) and ACP (6.6° ± 3.2° vs 2.1° ± 1.4°, P = .004).Conclusions:Our study found the currently tested SAS device may be a reasonable option as part of a 2-level hybrid construct, when used below an adjacent 1-level ACP, but should be used with careful consideration as a 2-level SAS construct. Consequences of decreased segmental stability in FE are unknown; however, optimal immediate fixation stability is an important surgical principle to avoid loss of fixation, segmental kyphosis, interbody graft subsidence, and pseudarthrosis.

Influence of manufacturing defects on modal properties of composite pyramidal truss-like core sandwich cylindrical panels

Defects can easily appear in composite lattice truss core sandwich structures during the complex preparation process, which may significantly affect the structural response and decrease the load-carrying capability. The purpose of this paper is to investigate the manufacturing defect sensitivity of modal vibration responses of carbon fiber composite pyramidal truss-like core sandwich cylindrical panels by modal experiments and finite element analysis. Defects including debonding between face sheets and truss cores (DFT), truss missing (DTM), face sheet wrinkling (DFW) and gap reinforcing (DGR) are introduced into the present intact specimen artificially and modal testing is conducted to study their dynamic behavior under free-free boundary conditions. Finite element models consistent with the experiments are then developed to further study the effect of defect extents, locations and forms on the modal parameters of the present sandwich cylindrical panels. Results indicate that the degree of sensitivity of natural frequencies of the present sandwich cylindrical panels mainly depends on the vibration modes, defect extents, locations and forms. In addition, damping loss factors are much more sensitive than their corresponding frequencies. Some conclusions and essential mechanisms are summarized, which is helpful to vibration-based non-destructive evaluation (NDE) of such kind of composite lattice sandwich structures.

Outcomes After Mini-Laparotomy for Tissue Extraction Following Laparoscopic Hysterectomy [19D

INTRODUCTION: Recognizing the importance of specimen integrity for patient care and pathologic evaluation, we aimed to determine if mini-laparotomy for tissue extraction of large specimens following laparoscopic hysterectomy would yield compromised outcomes when compared with vaginal extraction. METHODS: A retrospective analysis including all benign laparoscopic hysterectomies over a two year period was performed. Patients were separated into two groups depending on whether specimen was extracted vaginally or via mini-laparotomy. T-student and chi-square tests where used to assure both groups were homogenous to age, BMI, history of cesarean delivery and presence of diabetes or hypertension. Differences in complications, operating time, EBL and length of hospital stay between groups were determined. This was done via chi-square analysis. In the case of EBL and operating time, MANCOVA was employed to adjust for differences in specimen weight. RESULTS: A total of 225 patients were selected for analysis. There were no significant differences between vaginal extraction (n=157) and mini-laparotomy (n=68) groups in terms of age, BMI, previous cesarean deliveries, presence of diabetes or hypertension. No significant differences regarding presence of intraoperative (0.6% vs 1.5% p= 0.43) or postoperative complications (15.3% vs 7.4% p=0.10) were found. After controlling for specimen weight, there was no significant difference between groups with regard to operating time (143.66min vs 180.16min p=0.12), EBL (73.07ml vs 107.32ml p=0.80), or length of hospital stay (1248.71min vs 1512.21min p=0.98). CONCLUSION: Mini-laparotomy for tissue extraction is a safe approach and does not appear to add morbidity to minimally invasive hysterectomies, while conserving an intact specimen.

Characterization of sandwich beams with shear damages by linear and nonlinear vibration methods

The aim of the present work is to study the vibration behavior of sandwich composites with shear damages on the foams. The effect of the densities of damage on the linear and nonlinear vibration parameters is studied. The sandwich materials used in this study is constructed with glass fiber laminates as skins and with PVC closed-cell foams with density 60 and 100 kg m−3 as core. After a serie of vibration tests, the change of natural frequencies and modal damping due to the damage and the foam densities. For an intact specimen, the resonance frequency was constant when we increase the excitation amplitude. For damaged specimens, the resonance frequencies decrease and the loss factors increase proportionally with the increasing excitation amplitude. The nonlinear parameters corresponding to the elastic modulus and damping were determined for each frequency modes and each damage and foam densities. The results showed that nonlinear dissipative parameters were more sensitive to damage than linear elastic and dissipative parameters.

Evaluation of percutaneous vacuum assisted intact specimen breast biopsy device for ultrasound visualized breast lesions: Upstage rates and long term follow-up for high risk lesions and DCIS

ObjectivePercutaneous core biopsy of ultrasound visualized breast lesions is standard for diagnosis. Large gauge vacuum-assisted core needles have improved accuracy; but a significant underestimation of malignancy remains. The IntactR device was assessed for upstaging and subsequent malignancy at the biopsy site. Methods469 consecutive ultrasound visualized breast lesions, < 2.0 cm in size, BIRADS 4 or 5, biopsied with IntactR Breast Lesion Excision System, between July 2007 and August 2014, were reviewed. All non-concordant lesions (0.8%), DCIS (1.7%) and invasive cancers (9.8%) were surgically excised. Excision was recommended for all high risk lesions (13.0%). The upstage rate to DCIS or invasive cancer was determined. All patients were followed for a median of 66 months (24–96 months) with serial imaging and exams to determine the incidence of re-biopsy, or malignancy at the original biopsy site. Results23 of 61 high risk lesions (37.5%) were not excised, but observed for a median of 66 months. None required re-biopsy. One atypical lesion was upstaged to DCIS on excision. No patient was diagnosed with malignancy at or near the original biopsy site during follow-up. Overall upstage rate was 1.2%. ConclusionsPercutaneous biopsy of ultrasound visualized lesions was performed accurately using IntactR. Upstaging was much lower with IntactR than with large-gauge core needles. High risk lesions, diagnosed with IntactR, have a very low upstage rate at surgical excision. It may be possible to observe these lesions without surgery when they present as ultrasound findings and undergo IntactR biopsy.

Three-dimensional mouse brain cytoarchitecture revealed by laboratory-based x-ray phase-contrast tomography

Studies of brain cytoarchitecture in mammals are routinely performed by serial sectioning of the specimen and staining of the sections. The procedure is labor-intensive and the 3D architecture can only be determined after aligning individual 2D sections, leading to a reconstructed volume with non-isotropic resolution. Propagation-based x-ray phase-contrast tomography offers a unique potential for high-resolution 3D imaging of intact biological specimen due to the high penetration depth and potential resolution. We here show that even compact laboratory CT at an optimized liquid-metal jet microfocus source combined with suitable phase-retrieval algorithms and a novel tissue preparation can provide cellular and subcellular resolution in millimeter sized samples of mouse brain. We removed water and lipids from entire mouse brains and measured the remaining dry tissue matrix in air, lowering absorption but increasing phase contrast. We present single-cell resolution images of mouse brain cytoarchitecture and show that axons can be revealed in myelinated fiber bundles. In contrast to optical 3D techniques our approach does neither require staining of cells nor tissue clearing, procedures that are increasingly difficult to apply with increasing sample and brain sizes. The approach thus opens a novel route for high-resolution high-throughput studies of brain architecture in mammals.

Biomechanical comparison of acute Hill-Sachs reduction with remplissage to treat complex anterior instability

Acute Hill-Sachs reduction represents a potential alternative method to remplissage for the treatment of an engaging Hill-Sachs lesion. This study biomechanically compared the stabilizing effects of an acute Hill-Sachs reduction technique and remplissage. Six cadaveric shoulders were tested. For the acute Hill-Sachs lesion, a unique model was used to create a 30% defect, compressing the subchondral bone while preserving the articular surface. Five scenarios were tested: intact specimen, bipolar lesion, Bankart repair, remplissage with Bankart repair, and Hill-Sachs reduction technique with Bankart repair. The Hill-Sachs lesion was reduced through a lateral cortical window with a bone tamp, and the subchondral void was filled with bone cement. At 90° of abduction and external rotation (ER), total translation was 11.6 ± 0.9 mm for the bipolar lesion. This was significantly reduced after remplissage (5.9 ± 1.1 mm; P < .001) and after Hill-Sachs reduction (4.7 ± 0.4 mm; P < .001). Compared with an isolated Bankart repair, the average ER loss after remplissage was 4° ± 4° (P = .65), and the average ER loss after Hill-Sachs reduction was 1° ± 3° (P = .99). Similar joint stability was conferred after both procedures, with minimal change in range of motion. Remplissage may still be the best way to address chronic Hill-Sachs lesions; however, the reduction technique is a more anatomic alternative and may be a potential option for treating an acutely engaging Hill-Sachs lesion.