Reliability of three-dimensional motion analysis during single-leg side drop landing test after anterior cruciate ligament reconstruction: An in vivo motion analysis study.

Background: Anterior cruciate ligament (ACL) injury is a common sport injury and investigation of landing biomechanics is helpful in injury prevention and rehabilitation. Recent study found a lateral single-leg drop landing test resulted in the highest peak knee valgus angle (PKVA), but its reliability on patients who received ACL reconstruction (ACLR) is unknown. Objective: This study aimed to investigate the reliability in both within and between days on the normalized vertical ground reaction force (NVGRF) and kinematics of lower limbs after receiving ACLR. The findings can form the cornerstone for further study related to lateral jumping-and-landing biomechanics in patients with ACLR. Methods: This was a test-retest reliability study. Twelve patients (four females and eight males) who received ACLR with mean age of 29.4 (SD ± 1.66) were recruited. The subjects were instructed to jump laterally from 30 cm height and landed with single-leg for five times. The procedure was conducted on both legs for comparison. The NVGRF and local maxima of the hip, knee and ankle angles during the first 100 ms in all three planes were analyzed. The measurement was conducted by the same assessor to evaluate the within-session reliability, and the whole procedure was repeated one week later for the evaluation of the between-session reliability. Intra-class correlation coefficient (ICC) test was used to assess the within- and between-session reliability by ICC (3, 1) and ICC (3, K) respectively. Results: The within-session reliability of NVGRF [ICC (3, 1)] was 0.899-0.936, and its between-session reliability [ICC (3, K)] was 0.947-0.923. Overall reliability for kinematics within-session [ICC (3, 1)] was 0.948-0.988, and the between-session reliability [ICC (3, K)] was 0.618-0.982, respectively. Good to excellent reliability for the lateral single-leg drop landing test was observed in most of the outcome measures for within- and between-session. The ICC value of NVGRF of ACLR leg was lower than that of the good leg in the within-session which may associate with lower neuromuscular control in ACLR leg than that of the good leg. Conclusion: The results of this study support the use of a lateral single-leg drop landing test to evaluate lower limb biomechanics for ACLR.

Macromolecular dextran sulfate facilitates extracellular matrix deposition by electrostatic interaction independent from a macromolecular crowding effect.

A faithful reconstruction of the native cellular microenvironment is instrumental for tissue engineering. Macromolecular crowding (MMC) empowers cells to deposit their own extracellular matrix (ECM) in greater amounts, and thus contributes to building tissue-specific complex microenvironments in vitro. Dextran sulfate (DxS, 500 kDa), a semi-synthetic sulfated polyglucose, was shown previously at a fractional volume occupancy (FVO) of 5.2% (v/v; 100 µg/ml) to act as a potent molecular crowding agent in vitro. When added to human mesenchymal stromal cell (MSC) cultures, DxS enhanced fibronectin and collagen I deposition several-fold also at concentrations with negligible FVO (<1% v/v). In a cell-free system, incubation of culture media supplemented with fetal bovine serum (FBS), purified fibronectin or collagen I with DxS led to a co-deposition of respective components, exhibiting a similar granular pattern as observed in cell culture. Aggregation of FBS components, fibronectin or collagen I with DxS was confirmed by dynamic light scattering, where an increase in hydrodynamic radius in the respective mixtures was observed. FBS- and fibronectin aggregates could be dissociated with increasing salt concentrations, indicating electrostatic forces to be responsible for the aggregation. Conversely, collagen I-DxS aggregates increased in size with increasing ion concentration, likely caused by charge screening of collagen I, which is net negatively charged at neutral pH, thus permitting weaker intermolecular interactions to occur. The incorporation of DxS into the ECM resulted in altered ECM topography and stiffness. DxS-supplemented cultures exhibited potentiated bioactivity, such as enhanced adipogenic and especially osteogenic differentiation under inductive conditions. We propose an alternative mechanism by which DxS drives ECM deposition via aggregation, and in an independent manner from MMC. A deeper understanding of the underlying mechanism will enable optimized engineering approaches for ECM-rich tissue constructs.

Accuracy of GE digital breast tomosynthesis vs supplementary mammographic views for diagnosis of screen-detected soft-tissue breast lesions.

OBJECTIVE: To compare the accuracy of standard supplementary views and GE digital breast tomosynthesis (DBT) for assessment of soft-tissue mammographic abnormalities. METHODS: Women recalled for further assessment of soft-tissue abnormalities were recruited and received standard supplementary views (typically spot compression views) and two-view GE DBT. The added value of DBT in the assessment process was determined by analysing data collected prospectively by radiologists working up the cases. Following anonymization of cases, there was also a retrospective multireader review. The readers first read bilateral standard two-view digital mammography (DM) together with the supplementary mammographic views and gave a combined score for suspicion of malignancy on a five-point scale. The same readers then read bilateral standard two-view DM together with two-view DBT. Pathology data were obtained. Differences were assessed using receiver operating characteristic analysis. RESULTS: The study population was 342 lesions in 322 patients. The final diagnosis was malignant in 113 cases (33%) and benign/normal in 229 cases (67%). In the prospective analysis, the performance of two-view DM plus DBT was at least equivalent to the performance of two-view DM and standard mammographic supplementary views-the area under the curve (AUC) was 0.946 and 0.922, respectively, which did not reach statistical significance. Similar results were obtained for the retrospective review-AUC was 0.900 (DBT) and 0.873 (supplementary views), which did not reach statistical significance. CONCLUSION: The accuracy of GE DBT in the assessment of screen detected soft-tissue abnormalities is equivalent to the use of standard supplementary mammographic views. ADVANCES IN KNOWLEDGE: The vast majority of evidence relating to the use of DBT has been gathered from research using Hologic equipment. This study provides evidence for the use of the commercially available GE DBT system demonstrating that it is at least equivalent to supplementary mammographic views in the assessment of soft-tissue screen-detected abnormalities.