An established rabbit model was used to preliminarily investigate the effect of acellular triphase, namely bone-cartilage-tendon, scaffold (ATS) sandwiched with autologous bone mesenchymal stem cells (BMSCs) sheets on tendon-bone interface healing. Bone, fibrocartilage and tendon tissue were harvested from the rabbits and sectioned into a book-type scaffold. The scaffolds were decellularized and their characterization was presented. BMSCs were isolated and co-cultured with the scaffolds to verify their cytocompatibility. BMSCs sheets were fabricated and inserted into the book page of the scaffold to construct an autologous BMSCs-sheets/book-type ATS complex. The complex was implated in the right knee of rabbits which operated standard partial patellectomy for TBI regeneration using Imaging, histological and biomechanical examinations. The bone, fibrocartilage and tendon tissue were sectioned into a book-type scaffold before decellularization. Then we decellularized the above tissue and mostly preserved their microstructure and composition of the natural extracellular matrix, including collagen and proteoglycan. After the physicochemical and biological properties of the book-type ATS were evaluated, autologous BMSCs sheets were inserted into the book page of the scaffold to construct an autologous BMSCs-sheets/book-type ATS implants for TBI regeneration. In addition, the ATS has the advantages of non-toxicity, suitable for cell adhesion and growth as well as low immunogenicity while co-cultured with the BMSCs. At the same time, different scaffolds has the ability to induce the osteogenic, chondrogenic and tenogenic differentiation of BMSCs by immunofluorescence, reverse transcription-polymerase chain reaction and western blot analysis. To determine the efficacy of the tissue-engineered implants for TBI regeneration, we transplanted it into a rabbit patella-patellar tendon (PPT) injury model, and the rabbits were sacrificed at postoperative week 8 or 16 for the radiological, histological, and mechanical evaluation. Radiologically, Synchrotron radiation micro-computed tomography (SR-μCT) showed that BMSCs/ATS group significantly increased bone area, BV/TV, trabecular thickness and trabecular number at the healing interface as compared with other groups at postoperative week 8 or 16. Histologically, the BMSCs/ATS group showed more woven bone, and a more robust fibrocartilaginous junction with a characteristic matrix rich in proteoglycans was seen at the PPT healing interface in comparison with other groups after 8 weeks. At week 16, the healing interface in 3 groups displayed better remodeling with respect to postoperative week 8. Healing and remodeling at the PPT junction were almost complete, with a resemblance to a healthy BTI consisting of the characteristic 4 zones in all groups. At last, we used biomechanical test as functional parameters to evaluate the quality of tendon-bone healing. Biomechanical testing indicated that BMSCs/ATS group showed significantly higher failure load and stiffness than other groups at postoperative week 8 and 16. The complex composed of acellular triphase, namely bone-cartilage-tendon, scaffold (ATS) sandwiched with autologous bone mesenchymal stem cells (BMSCs) sheets can simulate the gradient structure of tendon-bone interface, inducing stem cell directional differentiation, so as to promote patella-patellar tendon interface healing effectively after injury.
Tibial and femoral component overhang in total knee arthroplasty (TKA) is a source of pain, thus is it important to understand anatomic differences between races to minimize overhang by matching the tibial and femoral shaft axis to the knee articular surface. Thus, this study compared knee morphology between Caucasian and East Asian individuals to determine the optimal placement of tibial and femoral stems. A retrospective study was conducted on a matched cohort of 50 East Asians (21F, 29M) and 50 Caucasians (21F, 29M) by age and gender. CT scans were obtained in healthy volunteers using <2mm slices. The distance from the proximal tibial diaphysis axis to the tibial plateau center was measured, and the distance from the distal femoral diaphysis axis to the center of distal femoral articular surface was measured. Tibial measurements were made using Akagi's AP axis and the widest ML diameter, and femoral measurements were based on Whiteside's line and the surgical epicondylar axis.Purpose
Methods
Self tapping bone screw has been widely used in the fixation of Arthroplasty implants and bone graft. But the unwanted screw or driver breakage can be a direct result of excessive driving torque due to the thread cutting resistance. Previous studies showed that bone drill bit cutting rake angle was a critical factor and was inversely related to the bone cutting efficiency.1, 2, 3, 4 (Figure 1) However to date there was no data for how the rake angle could influence the performance of self tapping bone screw. The purpose of this study was to investigate the torque generated by the self tapping cortical screw in simulated bone insertion as a function of the screw tip cutting flute rake angle. Two 5 mm thick BM5166 polyurethane block were stacked together and drilled through with 2.5mm diameter holes. Five 30mm long 3.5 mm diameter Ti6AL4V alloy self tapping cortical screws with 0°rake angle cutting flutes (Figure 2) were inserted in the holes and driven by the spanner attached to the test machine (Z5.0TN/TC-A-10) with a displacement control of 3 revolutions/min and 30N constant axial loading. The screws were driven into the stacked polyurethane block for 8mm depth. The maximum driving torque was recorded. Procedure was repeated for five same screws but with 7° rake angle cutting flutes. (Figure 2) The driving torqueses were compared. Student t test was performed with confidence level of 95% was assumed.Introduction
Methods
The purpose of this study was to investigate how rim poly locking scallop cutting depth could affect the rigidity of acetabular cup. (11) generic FEA models including (5) 50mm OD Ti6Al4VELI hemispherical acetabular shells with thicknesses of 3.0, 3.5, 4.0, 4.5 and 5.0mm, and (6) 4mm thick hemispherical shells with standard rim poly indexing scallops varied in cutting depths from inner diameter of the cup in 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5mm. All cups were analyzed in ANSYS® Workbench™ FEA software with a loading condition of 2000N applied to the cup rim per V15 ISO/TC 150/SC 4 N. Verification was carried out by the physical test of a same generic Ti6Al4VELI 50mmOD and 5mm thick solid hemispherical shell under 2000N rim directed load. The cup deformation was compared with FEA results. The maximum deformation of FEA scalloped cups were compared with that of solid hemispherical cups with different shell thickness.Objective
Materials and Methods
Fresh-frozen allograft bone is frequently used
in orthopaedic surgery. We investigated the incidence of allograft-related
infection and analysed the outcomes of recipients of bacterial culture-positive
allografts from our single-institute bone bank during bone transplantation.
The fresh-frozen allografts were harvested in a strict sterile environment
during total joint arthroplasty surgery and immediately stored in
a freezer at -78º to -68º C after packing. Between January 2007
and December 2012, 2024 patients received 2083 allografts with a
minimum of 12 months of follow-up. The overall allograft-associated
infection rate was 1.2% (24/2024). Swab cultures of 2083 allografts
taken before implantation revealed 21 (1.0%) positive findings.
The 21 recipients were given various antibiotics at the individual
orthopaedic surgeon’s discretion. At the latest follow-up, none
of these 21 recipients displayed clinical signs of infection following
treatment. Based on these findings, we conclude that an incidental positive
culture finding for allografts does not correlate with subsequent
surgical site infection. Additional prolonged post-operative antibiotic
therapy may not be necessary for recipients of fresh-frozen bone
allograft with positive culture findings. Cite this article:
The data regarding the effects of noggin on bone morphogenetic protein (BMP)-induced osteogenesis of mesenchymal stem cells (MSCs) are controversial. Most studies performed in rodent cells/models indicated that noggin was a negative regulator of BMP-2-induced osteogenesis; however, one study conducted with human MSCs in culture showed that the addition of noggin induced osteogenesis in vitro. To clear the controversy, we designed this study to evaluate the effects of knocking down noggin gene expression on BMP-2-induced osteogenesis of human bone marrow-derived primary MSCs in vitro. MSCs were isolated from human tibial bone marrow by density gradient centrifugation. Two noggin small interfering RNAs (siRNAs) were used in this study to knockdown noggin gene expression. There were four study groups: MSCs with no transfection of siRNA (named as NT group), MSCs transfected with non-targeting negative control siRNA (named as control group), MSCs transfected with noggin siRNA1 (named as NOGsi1 group), and MSCs transfected with noggin siRNA2 (named as NOGsi2 group). After transfection, MSCs were induced to undergo osteogenic differentiation by incubating in basal medium containing 0.1 μg/ml BMP-2 for 35 days. The expression levels of osteoblastic marker genes were measured by real-time quantitative PCR on day 14. Also assessed was alkaline phosphatase (ALP) activity by a colorimetric kinetic assay and Fast Blue B staining on day 14. Calcium deposition was determined by the calcium assay on day 35.Purpose
Method
