Background: Fatty infiltration and poor tendon-bone healing in chronic rotator cuff tears (RCTs) are associated with unsatisfactory prognosis. Adipose stem cell–derived exosomes (ASC-Exos), having multiple biological effects, can prevent muscle degeneration in acute RCTs. However, the effects of ASC-Exos on fatty infiltration and tendon-bone healing in chronic RCTs remain unknown. Purpose: To study the effects of ASC-Exos on fatty infiltration and tendon-bone healing in a chronic RCT rabbit model. Study Design: Controlled laboratory study. Methods: At week 0, we randomly allocated 35 rabbits to receive sham surgery (14 rabbits) or establish a bilateral RCT model (21 rabbits, detachment of the supraspinatus tendon). At week 6, a total of 7 rabbits received sham surgery, and 7 rabbits with RCT were sacrificed for fatty infiltration assay. The remaining 14 rabbits with bilateral RCTs were randomly assigned to a saline group (7 rabbits that received local saline injection and rotator cuff repair) or an ASC-Exos group (7 rabbits that received local ASC-Exos injection and rotator cuff repair). At week 18, all rabbits were sacrificed for histological examination and biomechanical testing. Results: At week 18, the ASC-Exos group showed significantly lower fatty infiltration (14.01% ± 2.85%) compared with the saline group (21.79% ± 3.07%) ( P < .001), and no statistical difference compared with the time of repair (10.88% ± 2.64%) ( P = .127). For tendon-bone healing, the ASC-Exos group showed a higher histological score and more newly regenerated fibrocartilage at the repair site than did the saline group. Regarding biomechanical testing, the ASC-Exos group showed significantly higher ultimate load to failure, stiffness, and stress than the saline group. Conclusion: Local injection of ASC-Exos in chronic RCTs at the time of repair could prevent the progress of fatty infiltration, promote tendon-bone healing, and improve biomechanical properties. Clinical Relevance: ASC-Exos injection may be used as a cell-free adjunctive therapy to inhibit fatty infiltration and improve rotator cuff healing in the repair of chronic RCTs.
HLA-DRB1 shared epitope allele polymorphisms and rheumatoid arthritis: a systemic review and meta-analysis Abstract Purpose: A meta-analysis was preformed to determine which HLA-DRB1 alleles are associated with increased risk of rheumatoid arthritis (RA) in Asian patients.
Background: The stability ratio (SR) is an important biomechanical parameter for evaluating glenoid stability in patients with recurrent anterior shoulder dislocation (RASD), and it cannot be practically and conveniently measured in clinical scenarios. Purpose: To investigate a novel computed tomography (CT)–based protocol to estimate the SR efficiently. Study Design: Descriptive laboratory study. Methods: A total of 102 patients with RASD were included. Demographic information, CT scans, and bone defect area (BDA) were collected. The new protocol, based on balance stability angle (BSA) measurements on CT, was conducted to estimate the SR (SRCT) by 2 surgeons independently. Biomechanical testing was then performed on patient-specific 3-dimensional (3D)–printed glenoid models to calculate the SR (SR3Dprint), which was used to (1) analyze the reliability of SRCT and (2) examine if the BDA could predict SR3Dprint. To validate whether the 3D-printed glenoid could reflect the actual biomechanical properties of the shoulder, the SR from 5 cadaveric glenoid specimens (SRcadaver) was also calculated and compared with that from the 3D-printed glenoid (SR3Dprint) under 6 osteotomy conditions. Linear regression and intraclass correlation coefficients (ICCs) were used for statistical analysis. Results: The interrater reliability of SRCT measurements was high (ICC = 0.95). SRCT was highly correlated with SR3Dprint ( R 2 = 0.86; ICC = 0.92). The mean BDA was 11.44% ± 6.72% by the linear ratio method, with a weak correlation with SR3Dprint ( R 2 = 0.31; ICC = -0.46). The cadaveric validation experiment indicated that SRcadaver was highly correlated with SR3Dprint ( R 2 = 0.86; ICC = 0.77). Conclusion: Results indicated that (1) the proposed CT-based protocol of obtaining BSA measurements is promising for the SR estimation in patients with RASD, (2) the BDA was not an effective parameter to predict the biomechanical SR, and (3) the 3D-printed glenoid could reflect the biomechanical properties of cadaveric shoulders regarding the SR estimation. Clinical Relevance: Traditional BDA measurements cannot accurately reflect the biomechanical stability of the glenoid. The newly proposed CT-based protocol is practical for surgeons to estimate the SR.
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