Mechanical properties evaluation of metacarpophalangeal joint prosthesis with new titanium-nickel memory alloy: a cadaver study.

OBJECTIVE: Ni-Ti memory alloys are unusual materials for hard-tissue replacement because of their unique superelasticity, good biocompatibility, high strength, low specific gravity, low magnetism, wear resistance, corrosion resistance and fatigue resistance. The current study aims to evaluate its mechanical properties and provide biomechanical basis for the clinical application of the prosthesis. METHODS: Ten adult metacarpophalangeal joint specimens were randomly divided into a prosthesis group (n = 5, underwent metacarpophalangeal joint prosthesis) and a control group (n = 5, underwent sham operation). Firstly, the axial compression strength was tested with BOSE material testing machine to evaluate its biomechanical strength. Secondly, these specimens were tested for strain changes using BOSE material testing machine and GOM non-contact optical strain measurement system to evaluate the stress changes. Thirdly, fatigue test was performed between groups. Lastly, the mechanical wear of the metacarpophalangeal joint prosthesis was tested with ETK5510 material testing machine to study its mechanical properties. RESULTS: Axial compression stiffness in the prosthesis group was greater than that in the control group in terms of 30 ° and 60 ° flexion positions (P < 0.05). There was no statistically significant difference between two groups with regards to axial compression stiffness and stress change test (P > 0.05). In the fatigue wear test, the mean mass loss in the prosthesis group's prosthesis was 17.2 mg and 17.619 mm3, respectively. The mean volume wear rate was 0.12%. There was no statistically significant difference in the maximum pull-out force of the metacarpal, phalangeal, and polymer polyethylene pads between the prosthesis group and the control group specimens. CONCLUSIONS: Ni-Ti memory alloy metacarpophalangeal joint prosthesis conforms to the biomechanical characteristics of metacarpophalangeal joints without implants, and the fatigue strength can fully meet the needs of metacarpophalangeal joint activities after joint replacement.

circRNA-ZCCHC14 affects the chondrogenic differentiation ability of peripheral blood-derived mesenchymal stem cells by regulating GREM1 through miR-181a.

circRNAs play an important role in the progression of osteoarthritis (OA). Therefore, we aimed to reveal the mechanism of action of circRNA-ZCCHC14 in OA. OA animal and cell models were constructed, and clinical samples were collected. The expression of circRNA-ZCCHC14 and miR-181a was detected by RT‒qPCR. The chondrogenic differentiation ability of peripheral blood-derived mesenchymal stem cells (PBMSCs) was detected by Alcian blue staining. The expression of chondrogenic differentiation-related proteins was detected by Western blotting. Double fluorescein experiments verified the targeting relationship of miR-181a with circRNA-ZCCHC14 and GREM1. Upregulation of circRNA-ZCCHC14 was observed in blood, in BMP-2- and TGF-ß3-treated PBMSCs from OA patients and in animal models. Knockdown of circRNA-ZCCHC14 promoted the chondrogenic differentiation ability of PBMSCs. circRNA-ZCCHC14 was found to bind to miR-181a and negatively regulate miR-181a expression. Inhibition of miR-181a reversed the promoting effect of circRNA-ZCCHC14 knockdown on the chondrogenic differentiation ability of PBMSCs. GREM1 was identified as a target of miR-181a. Overexpression and knockdown of GREM1 regulated the expression of BMP2, which in turn affected the chondrogenic differentiation ability of PBMSCs, indicating that GREM1 and BMP2 have antagonistic effects and that they jointly regulate the chondrogenic differentiation of PBMSCs. circRNA-ZCCHC14 may promote the chondrogenic differentiation ability of PBMSCs by regulating miR-181a and inhibiting the expression of GREM1.

The outcomes of one-stage treatment for multiple knee ligament injuries combined with extensor apparatus rupture.

BACKGROUND: Multiple knee ligament injuries combined with extensor apparatus rupture are serious and complex knee injuries that are rare in clinical practice. The management is extremely challenging and controversial. The aim of this study is to describe a patient collective with multiple knee ligament injuries combined with extensor apparatus injuries in detail and to report the mid-term outcomes of a one-stage surgical treatment regarding subjective outcome scores, complications, knee instability, and ROM. METHODS: Eleven of 425 patients with multiple knee ligament injuries combined with extensor apparatus injuries admitted to our hospital were reviewed from July 2008 to May 2017. All patients underwent one-stage repair and reconstruction of multiple knee ligaments and extensor apparatus. The Lysholm knee score and the International Knee Documentation Committee (IKDC) score were adopted to evaluate the surgical effect preoperatively and at a minimum of 2 years' follow-up. Clinical data, including range of motion and knee stability, were also recorded at the final follow-up. RESULTS: Ten patients were followed up with a mean time of 40 (range, 24-60) months. At the last follow-up, 8 patients had joint flexion range of motion greater than or equal to120 degrees, 2 patients had joint flexion range of motion of 100-120 degrees, and 1 patient had active knee extension limitation of 5 degrees. Stress radiographs showed that the mean differences in posterior displacement were reduced from 10.8 ± 3.0 mm preoperatively to 2.0 ± 2.5 mm at the last follow-up. There were significant improvements in stress radiographs from pre- to postoperative states for all patients with multiple knee ligament injuries. The Lysholm score ranged from 85 to 96, with a mean of 92.1 (compared with 33 before surgery, P < 0.05). The final IKDC scores were A in 2 patients (20%), B in 7 (70%), and C in 1 (10%). Nine of the 10 patients (90%) returned to their former activity level. CONCLUSION: Multiple knee ligament injuries combined with extensor apparatus rupture are rare. Single-stage management of the repair and reconstruction of multiple knee ligaments and extensor apparatus with proper rehabilitation is an effective and reliable procedure to restore knee stability and function. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Peripheral Blood Mesenchymal Stem Cells Combined with Modified Demineralized Bone Matrix Promote Pig Cartilage Defect Repair.

OBJECTIVE: To investigate the mobilization of peripheral blood mesenchymal stem cells (PBMSCs) and whether a combination of PBMSCs and modified demineralized bone matrix (DBM) promoted the repair of cartilage lesions in a pig model. METHODS: Pig PBMSCs were mobilized by the combined administration of granulocyte colony-stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100. Colony formation was detected by the fibroblast colony-forming unit (CFU-F) count and the percentage of the CD45-CD90+ cell population by flow cytometry. The mobilized cells were identified as MSCs by their morphological characteristics, surface markers, and differentiation potentials. The composite scaffolds carrying BMP-2 and TGF-ß3 chitosan sustained-release microspheres/DBM were prepared by emulsion cross-linking and the Urist method, and scanning electron microscopy (SEM) observation was performed. The model of pig cartilage defect was prepared, and gross observation, histological examination, immunohistochemistry, and O'Driscoll scoring were performed 4, 8, and 12 weeks postoperation. RESULTS: After mobilization, the number of CFU-Fs in the peripheral blood in the experimental group (G-CSF + AMD3100) was significantly increased compared with the control group (p < 0.05). The proportion and total number of CD45-CD90+ cells were increased (p < 0.05). The mobilized stem cells had MSC characteristics. SEM of the new tissue-engineered cartilage showed that PBMSCs were evenly grown on the surface of the scaffold and microsphere morphology had no obvious change. Gross observation, histological examination, immunohistochemistry, and O'Driscoll score were better in the experimental group than in the other groups (p < 0.05). CONCLUSION: G-CSF + AMD3100 is an effective mobilization agent for PBMSCs. The new tissue-engineering cartilage constructed by two-factor sustained-release microspheres/DBM composite PBMSCs effected good repair of the cartilage defect in pigs.