Citations

Objectives The goal of this study was to determine whether intra-articular administration of the potentially anti-fibrotic agent decorin influences the expression of genes involved in the fibrotic cascade, and ultimately leads to less contracture, in an animal model. Methods A total of 18 rabbits underwent an operation on their right knees to form contractures. Six limbs in group 1 received four intra-articular injections of decorin; six limbs in group 2 received four intra-articular injections of bovine serum albumin (BSA) over eight days; six limbs in group 3 received no injections. The contracted limbs of rabbits in group 1 were biomechanically and genetically compared with the contracted limbs of rabbits in groups 2 and 3, with the use of a calibrated joint measuring device and custom microarray, respectively. Results There was no statistical difference in the flexion contracture angles between those limbs that received intra-articular decorin versus those that received intra-articular BSA (66° vs 69°; p = 0.41). Likewise, there was no statistical difference between those limbs that received intra-articular decorin versus those who had no injection (66° vs 72°; p = 0.27). When compared with BSA, decorin led to a statistically significant increase in the mRNA expression of 12 genes (p < 0.01). In addition, there was a statistical change in the mRNA expression of three genes, when compared with those without injection. Conclusions In this model, when administered intra-articularly at eight weeks, 2 mg of decorin had no significant effect on joint contractures. However, our genetic analysis revealed a significant alteration in several fibrotic genes. Cite this article: Bone Joint Res 2014;3:82–8.

Abstract Induced pluripotent stem cells (iPSCs) derived from somatic cells of patients can be a good model for studying human diseases and for future therapeutic regenerative medicine. Current initiatives to establish human iPSC (hiPSC) banking face challenges in recruiting large numbers of donors with diverse diseased, genetic, and phenotypic representations. In this study, we describe the efficient derivation of transgene-free hiPSCs from human finger-prick blood. Finger-prick sample collection can be performed on a “do-it-yourself” basis by donors and sent to the hiPSC facility for reprogramming. We show that single-drop volumes of finger-prick samples are sufficient for performing cellular reprogramming, DNA sequencing, and blood serotyping in parallel. Our novel strategy has the potential to facilitate the development of large-scale hiPSC banking worldwide.

AbstractPurposeThe goals of part 2 of the study presented here were 1) to assess whether there is a difference in failure mode of different thicknesses (2.0, 1.5, 1.0, and 0.5 mm) of anatomically standardized full contour monolithic lithium disilicate restorations for posterior teeth, and 2) to assess if there is a difference among various crown thicknesses when these restorations are subjected to dynamic load forces common for posterior teeth.Materials and MethodsFour groups (n = 10), each with a different thickness of anatomically appropriate all‐ceramic crowns, were to be tested as established from the statistical analysis of the preliminary phase. Group 1: 2.0 mm; group 2: 1.5 mm; group 3: 1.0 mm; group 4: 0.5 mm. The specimens were adhesively luted to the corresponding die, and underwent dynamic cyclic loading (380 to 390 N) completely submerged in an aqueous environment until a failure was noted by graphic recording and continuous monitoring.ResultsThere was a statistically significant difference of the fatigue cycles to failure among four groups (p < 0.001; Kruskal‐Wallis test). The mean number of cycles to fail for 2.0 mm specimens was 17 times more than the mean number of cycles to fail for 1.0 mm specimens and 1.5 times more than the mean number of cycles to fail for 1.5 mm specimens. The 0.5 mm specimens failed with one cycle of loading. A qualitative characteristic noted among the 2.0 mm specimens was wear of the area of indenter contact followed by shearing of the material and/or crack propagation.ConclusionBased on the findings of this study, it may be reasonable to consider a crown thickness of 1.5 mm or greater for clinical applications of milled monolithic lithium disilicate crowns for posterior single teeth.

Background This study investigated the effects of a series of four hypertonic dextrose injections on the subsynovial connective tissue (SSCT) and median nerve within the carpal tunnel of a rabbit model. Methods Twenty New Zealand white rabbits were used. One forepaw carpal tunnel was randomly injected with 0.1 ml of 10 % dextrose solution. The contralateral forepaw was injected with a similar amount of saline. This injection was made once per week for 4 weeks. The animals were killed at 16 weeks after the initial injection and were evaluated by electrophysiology (EP), SSCT mechanical testing, and histology. Results Mechanical testing revealed significantly greater ultimate load and energy absorption in the dextrose injection group compared to the saline injection group ( P<0.05). Histological evaluation revealed SSCT fibrosis and thickening and edema in the median nerve bundles in the dextrose injection group. There was a prolongation in the latency of the EP test in the dextrose injection group ( P=0.08). Conclusions Previous studies had shown that one or two injections of 10 % dextrose could induce moderate SSCT fibrosis and mild EP changes without nerve histology changes. In this study, we have shown that higher doses create more severe fibrosis and, most importantly, more severe neuropathy, suggesting a dose–response effect, and confirming this as a potentially useful animal model for researching the etiology and treatment of carpal tunnel syndrome.

Purpose The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for small‐ and large‐sized Hill‐Sachs lesions (HSLs) on shoulder range of motion (ROM) with a special interest in the apprehension position. Methods HSLs of 50% and 100% of the glenoid width were simulated in 7 cadaveric shoulders as small and large lesions, respectively, and the postoperative condition was reproduced by placing suture anchors on the articular surface and tying down the infraspinatus at the medial edge of the would‐be lesion site. ROMs were measured in abduction, internal rotation, and external rotation with the humerus in the adducted and abducted position. In addition, the ROM was measured in the anterior apprehension position, in which 2 torques of external rotation and extension were applied simultaneously, and external rotation and horizontal extension ROMs were measured with the humerus in different abduction angles (20°, 40°, and 60°). Results For standard ROMs, the procedure for the 50% HSL maintained complete ROMs, whereas the procedure for the 100% HSL significantly decreased external rotation ROM with the humerus in both the adducted and abducted positions, as well as abduction ROM. In the apprehension position, remplissage for the 50% HSL decreased extension ROM with the humerus abducted to 40° and 60°. Remplissage for the 100% HSL significantly decreased both external and extension ROMs regardless of the humeral abduction angle. Conclusions In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and external rotation with the humerus in both adduction and abduction. It also caused significant restrictions in both external rotation and extension ROMs in the apprehension position. Clinical Relevance The indication for the remplissage procedure for the larger HSL should be considered carefully, especially for the competitive throwing athlete who needs exceptional external rotation ROM for optimal overhead throwing performance.

One commonly reported complication of pyrolytic carbon arthroplasty at the proximal interphalangeal (PIP) joint is an annoying, painless, squeaking postoperatively. This squeak has been anecdotally associated with implant loosening or impending dislocation. The purpose of this study was to investigate the etiology of this squeaking. Proximal and distal components of the pyrolytic carbon PIP implant were inserted into foam bones and mounted onto an oscillating test device. We evaluated the effect of 96 combinations of load, velocity, contact angle, implant size, lubrication, and displacement amplitude over a total of 300 cycles for each condition. Sound analysis was performed on squeaking conditions. Fourteen conditions resulted in squeaking, all with a sound pattern similar to that noted clinically. Unlubricated, “dry” joints did not squeak. Squeaking most commonly occurred with fetal bovine serum lubrication, at higher loads, and at 0 deg hyperextension. Hyaluronic acid viscosupplementation stopped the squeaking in all cases.

The supraspinatus tendon consists morphologically of two sub‐regions, anterior and posterior. The anterior sub‐region is thick and tubular while the posterior is thin and strap‐like. The purpose of this study was to compare the structural and mechanical properties of the anterior and posterior sub‐regions of the supraspinatus tendon. The supraspinatus tendons from seven human cadaveric shoulders were morphologically divided into the anterior and posterior sub‐regions. Length, width, and thickness were measured. A servo‐hydraulic testing machine (MTS Systems Corporation, Minneapolis, MN) was used for tensile testing. The maximal load at failure, modulus of elasticity and ultimate tendon stress were calculated. Repeated measures were used for statistical comparisons. The mean anterior tendon cross‐sectional area was 47.3 mm2 and the posterior was 32.1 mm2. Failure occurred most often at the insertion site: anterior (5/7) and posterior (6/7). All parameters of the anterior sub‐region were significantly greater than those of the posterior sub‐region. The moduli of elasticity at the insertion site were 592.4 MPa in the anterior sub‐region and 217.7 MPa in the posterior (P = 0.01). The ultimate failure loads were 779.2 N in the anterior sub‐region and 335.6 N in the posterior (P = 0.003). The ultimate stresses were 22.1 MPa in the anterior sub‐region and 11.6 MPa in the posterior (P = 0.008). We recognized that the anterior and posterior sub‐regions of the SSP tendon have significantly different mechanical properties. In a future study, we need to evaluate how best to repair an SSP tendon considering these region‐specific properties. Clin. Anat. 27:702–706, 2014. © 2013 Wiley Periodicals, Inc.

SUMMARYFibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel is the most common histological finding in carpal tunnel syndrome (CTS). Fibrosis may result from damaged SSCT. Previous studies found that with low‐velocity (2 mm/s), tendon excursions can irreversibly damage the SSCT. We investigated the effect of tendon excursion velocity in the generation of SSCT damage. Nine human cadaver wrists were used. Three repeated cycles of ramp‐stretch testing were performed simulating 40%, 60%, 90%, and 120% of the middle finger flexor tendon superficialis physiological excursion with an excursion velocity of 60 mm/s. Energy and force were calculated and normalized by values obtained in the first cycle for each excursion level. Data were compared with low‐velocity excursion data. For high‐velocity excursions, a significant drop in the excursion energy ratio was first observed at an excursion level of 60% physiological excursion (p < 0.024) and that for low‐velocity excursions was first observed at 90% physiological excursion (p < 0.038). Furthermore, the energy ratio was lower at 60% for high velocities (p ≤ 0.039). Increasing velocity lowers the SSCT damage threshold. This finding may be relevant for understanding the pathogenesis of SSCT fibrosis, such as that accompanying CTS, and a relationship with occupational factors. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:123–128, 2014.

ABSTRACTNon‐inflammatory fibrosis of the subsynovial connective tissue (SSCT) is a hallmark of carpal tunnel syndrome (CTS). The etiology of this finding and its relationship to the development of CTS remain poorly understood. Recent studies have found that transforming growth factor‐β (TGF‐β) plays a central role in fibrosis. The purpose of this study was to investigate the expression of TGF‐β and connective tissue growth factor (CTGF), a downstream mediator of TGF‐β, in the pathogenesis of CTS. We compared SSCT specimens from 26 idiopathic CTS patients with specimens from 10 human cadaver controls with no previous diagnosis of CTS. Immunohistochemistry was performed to determine levels TGF‐β1, CTGF, collagen 1(Col1) and collagen 3 (Col3) expression. TGF‐β1 (p < 0.01), CTGF (p < 0.01), and Col3 (p < 0.01) were increased in SSCT of CTS patients compared with control tissue. In addition, a strong positive correlation was found between TGF‐β1 and CTGF, (R2 = 0.80, p < 0.01) and a moderate positive correlation between Col3 and TGF‐β1 (R2 = 0.49, p < 0.01). These finding suggest that there is an increased expression of TGF‐β and CTGF, a TGF‐β regulated protein, and that this TGF‐β activation may be responsible for SSCT fibrosis in CTS patients. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:116–122, 2014.