Modulation of signaling pathways, which involves tendon development, regeneration, or homeostasis, is one of the potential modalities to facilitate proper regeneration of the injured tendon. Authors have previously reported that activation of Wnt/beta-catenin signaling suppressed the expression of tenogenic genes (i.e. Scleraxis (Introduction
Materials and Methods
Lubricin is a proteoglycan that is a boundary lubricant in synovial joints and both a surface and collagen inter-fascicular lubricant in ligaments. The purpose of this study was to characterise the mRNA levels for lubricin in the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL) in aging and surgically-induced menopausal rabbits. We hypothesised that lubricin mRNA levels would be increased in ligaments from aging and menopausal rabbits compared with ligaments from normal rabbits. All four knee ligaments (ACL, PCL, MCL, LCL) were isolated from normal (1-year-old rabbits, n=8), aging (3-year-old rabbits, n=6), and menopausal (1-year-old rabbits fourteen weeks after surgical ovariohysterectomy, n=8) female New Zealand White rabbits. RT-qPCR was used to evaluate the mRNA levels for lubricin normalised to the housekeeping gene 18S. After removing outliers, data for normal, aging, and menopausal rabbits for each knee ligament (ACL, PCL, MCL, LCL) were compared using ANOVA with linear contrasts or Kruskal-Wallis test with Conover post-hoc analysis. For ACLs, the mRNA levels for lubricin were increased in menopausal and aging rabbits compared with normal rabbits (p<0.056). For PCLs, trends for increased lubricin mRNA levels were found when comparing menopausal and aging rabbits with normal rabbits (p<0.092). For MCLs, the mRNA levels for lubricin were increased in menopausal and aging rabbits compared with normal rabbits (p<0.050). For LCLs, no differences in lubricin mRNA levels were detected comparing the three groups. For all four knee ligaments (ACL, PCL, MCL, LCL), no differences in lubricin mRNA levels were detected comparing the ligaments from menopausal rabbits with those from aging rabbits. Lubricin plays a role in collagen fascicle lubrication in ligaments (1,2). Increased lubricin gene expression was associated with mechanical changes (including decreased modulus and increased failure strain) in the aging rabbit MCL (3). Detection of similar molecular changes in the ACL, and possibly the PCL, may indicate that their mechanical properties may also change as a result of increased lubricin gene expression, thereby potentially pre-disposing these ligaments to damage accumulation. Compared to aging ligaments, aging tendons exhibited decreased lubricin gene and protein expression, and increased stiffness (4). Although opposite changes than aging ligaments, these findings support the relationship between lubricin and modulus/stiffness. The similarities between ligaments in the aging and menopausal groups may suggest that surgically-induced menopause results in a form of accelerated aging in the rabbit ACL, MCL and possibly PCL.
This study evaluated the mechanical performance, under low-load cyclic loading, of two different knotless suture anchor designs: sutures completely internal to the anchor body (SpeedScrew) and sutures external to the anchor body and adjacent to bone (MultiFIX P). Using standard suture loops pulled in-line with the rotator cuff (approximately 60°), anchors were tested in cadaveric bone and foam blocks representing normal to osteopenic bone. Mechanical testing included preloading to 10 N and cyclic loading for 500 cycles from 10 N to 60 N at 60 mm/min. The parameters evaluated were initial displacement, cyclic displacement and number of cycles and load at 3 mm displacement relative to preload. Video recording throughout testing documented the predominant source of suture displacement and the distance of ‘suture cutting through bone’.Objectives
Methods
Surgical site infection (SSI) is an infrequent but serious complication of total joint arthroplasty (TJA). Orthopaedic SSI causes substantial morbidity, prolonging the hospital stay by a median of 2 weeks, doubling the rates of rehospitalization, and more than tripling overall healthcare costs. Colonization with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) is known to be associated with an increased risk of subsequent SSI. Carriers are two to nine times more likely to acquire S. aureus SSIs than non-carriers. Screening of the nose and throat for MRSA colonization and preoperative patient decolonization have been shown to decrease the incidence of subsequent MRSA infection. The aim of this study was to investigate the association between the results of MRSA colonization screening and the incidence of SSI in our hospital. Between June 2007 and June 2010, 238 patients were admitted for TJA, among whom 235 underwent preoperative assessment that included screening of the nose and throat for MRSA colonization. Fifty-nine of these patients underwent total hip arthroplasty (THA), 69 underwent total knee arthroplasty (TKA), 6 underwent unilateral knee arthroplasty (UKA), and 101 underwent bipolar hip prosthesis arthroplasty (BPH). The mean age of the patients was 72.7 (49–95) years and the male to female ratio was 1:3.8. We analyzed these patients retrospectively, and determined the site of colonization, eradication prior to surgery, and subsequent development of SSI in the year after surgery. SSI was defined according to the criteria established by the Centers for Disease Control and Prevention.Purpose
Materials and Methods
