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Background: The mechanical properties of extracellular matrix grafts that are intended to augment or replace soft tissues should be comparable to the native tissue. Such grafts are often used in fiber-reinforced tissue applications that undergo multi-axial loading and therefore knowledge of the anisotropic and nonlinear properties are needed, including the moduli and Poisson's ratio in two orthogonal directions within the plane of the graft. The objective of this study was to measure the tensile mechanical properties of several marketed grafts: Alloderm, Restore, CuffPatch, and OrthADAPT., Methods: The degree of anisotropy and non-linearity within each graft was evaluated from uniaxial tensile tests and compared to their native tissue., Findings: The Alloderm graft was anisotropic in both the toe- and linear-region of the stress-strain response, was highly nonlinear, and generally had low properties. The Restore and CuffPatch grafts had similar stress-strain responses, were largely isotropic, had a linear-region modulus of 18MPa, and were nonlinear. OrthADAPT was anisotropic in the linear-region (131 MPA vs 47MPa in the toe-region) and was highly nonlinear. The Poisson ratio for all grafts was between 0.4 and 0.7, except for the parallel orientation of Restore which was greater than 1.0., Interpretation: Having an informed understanding of how the available grafts perform mechanically will allow for better assessment by the physician for which graft to apply depending upon its application., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The feasibility that temperature field measurements in vitro as an alternative way to characterize the high intensity focused ultrasound (HIFU) field used in therapeutic applications has been explored in a phantom study. Thermocouples (copper-constantan, diameter 0.125 mm) are embedded in a phantom filled with tissue mimicking material that simulates the thermal and acoustic properties of soft-tissue. The temperature rises as a function of ultrasound exposure time near the focus of a HIFU transducer (1.1 MHz, active radius a=32 mm, geometric focal length=62 mm) of various acoustic powers up to 30 W are measured and compared with predicted values using a simple nonlinear Gaussian model. The experimental results can be explained well by the model if no acoustic cavitation takes place. When the acoustic power become higher (>5 W) and the local temperature elevation >15 degrees C and the local temperature is >40 degrees C at the focal point, cavitation vapor bubbles appear. The presence of the cavitation bubbles may increase the temperature rise rate initially. The bubble aggregates may form along the beam axis under sonication and then eventually makes the temperature elevation reach a saturated value. When acoustic cavitation occurs, the bubble-assisted enhancement of the initial temperature rise (exposure time t<2s) can still be predicted by the theory.

Background: The purpose of this study was to evaluate the effect of flexor retinaculum division (simulated carpal tunnel release) on the relative motion of flexor tendon, subsynovial connective tissue, and median nerve in human cadaver specimens., Methods: Using fluoroscopy, we measured the relative motion of middle finger flexor digitorum superficialis tendon, subsynovial connective tissue, and median nerve in twelve human cadavers with simulated fist motion. Measurements were obtained for three wrist positions: neutral; 60 degrees flexion; and 60 degrees extension. The shear index was defined as the difference in motion between two tissues (tendon, subsynovial connective tissue, or nerve) relative to tendon excursion, expressed as a percentage. After testing with an intact carpal tunnel, the flexor retinaculum was cut and the testing procedure was repeated., Findings: With an intact flexor retinaculum, the wrist flexion position showed significantly less displacement for the subsynovial connective tissue and median nerve relative to tendon displacement, and thus the highest potential shear strain between subsynovial connective tissue-tendon, and tendon-nerve. The wrist extension position also had a significantly higher potential shear strain for tendon-nerve compared to the neutral position. After division of the flexor retinaculum, the differences in shear index among wrist positions were reduced. For the wrist flexion position, the subsynovial connective tissue and median nerve displacements significantly increased, indicating lower shear index values., Interpretation: These findings suggest that division of flexor retinaculum reduces the potential shear strain and thus possibly the risk of shear injury to tissues with the carpal tunnel.

Purpose: To report a surgical technique and the results of rectus muscle posterior Tenon fixation as an inactivation procedure for treatment of Duane syndrome, restrictive strabismus, and long-standing paralytic strabismus, which conventionally require large rectus muscle recession., Design: Prospective, interventional case series., Methods: Three eyes in three Duane syndrome patients, one eye in one myopic strabismus fixus patient, one eye in one complete third nerve palsy patient, and one eye in complete sixth nerve palsy patient underwent rectus muscle inactivation by disinsertion and posterior Tenon fixation of its insertion. The main outcome measures were the postoperative eye position in all patients, the presence of upshoot or downshoot on adduction, and, in Duane syndrome patients only, the height of the palpebral fissure., Results: In Duane syndrome patients, the upshoot and the downshoot were improved markedly, and the height of the palpebral fissure was increased on adduction after the operation as compared with before the operation; the other patients had improved ocular alignment after surgery., Conclusions: We believe that rectus muscle inactivation by fixation of its insertion to posterior Tenon is an effective and less invasive technique for achieving profound weakening of a rectus muscle compared with periosteal fixation of the rectus muscle.

Purpose: To evaluate the effectiveness of conjunctival resection combined with Tenon layer excision in treating superior limbic keratoconjunctivitis (SLK) and the involvement of mast cells in SLK., Design: Retrospective, interventional case series., Methods: Forty eyes of 30 SLK patients who were unresponsive to medical treatment received superior bulbar conjunctival resection, and another 20 patients who underwent cataract and retinal surgery served as a control group. The conjunctiva specimens from study and control patients were examined by hematoxylin and eosin staining and immunohistochemistry using antibodies against mast cell tryptase., Results: In all operated eyes, the clinical symptoms and signs, including irritation and redness and superior bulbar conjunctival hyperemia and superior tarsal conjunctival papillary hypertrophy, subsided significantly three months after the operation. Only three eyes had recurrence from the margin of conjunctival resection, and this was relieved after reoperation. Keratinized conjunctival epithelium, loss of goblet cells, and increased mast cell numbers (P<.05) were found in the SLK group., Conclusions: Our cases demonstrate that superior bulbar conjunctival resection combined with Tenon layer excision is an effective treatment for SLK. The pathologic findings suggest that mast cells may play a role in the pathogenesis of SLK.

Purpose: To determine the effect of arteriovenous sheathotomy on retinal blood flow (RBF) in eyes with branch retinal vein occlusion (BRVO)., Design: Interventional case series., Methods: Seven eyes of 7 patients with BRVO underwent sheathotomy and were followed for more than 6 months., Results: At 1 week postoperatively, the RBF in the affected vessels was significantly improved from 14.1 +/- 5.7 to 27.3 +/- 11.3 pixel(2)/sec (P < 0.01), and the foveal thickness (FT) was significantly reduced from 536 +/- 84 to 366 +/- 134 microm (P = 0.03). However, the RBF was reduced again to 11.7 +/- 7.7 pixel(2)/sec at 1 month postoperatively, and the FT was increased to 424 +/- 184 microm., Conclusions: Arteriovenous sheathotomy led to a transient improvement of the RBF and was effective in reducing macular edema. It is not clear whether the transient effect of sheathotomy affects the long-term visual acuity and macular edema.

Purpose: compare the results of vitrectomy with or without arteriovenous (AV) crossing sheathotomy for macular edema associated with branch retinal vein occlusion (BRVO)., Design: Interventional case series., Methods: A retrospective study of 36 eyes with BRVO-associated macular edema. Twenty eyes underwent AV sheathotomy (AS group), and 16 eyes underwent posterior vitreous detachment (PVD group). Best-corrected visual acuity (BCVA), fluorescein angiography (FA), and optical coherence tomography to determine foveal thickness were conducted preoperatively and at 12 months postoperatively., Results: The mean postoperative BCVAs were significantly better in both the AS and the PVD group (P = .008 and P = .001, respectively). Foveal thickness decreased significantly 1 month after surgery in both groups (P = .002 and P = .007) and continued to decrease up to 12 months. The postoperative mean BCVA and improvement of BCVA and foveal thickness were not significantly different for the two groups at any postoperative period. Postoperative FA showed reperfusion of the occluded vein in 10 eyes in the AS group and 2 eyes in the PVD group, and formation of shunt vessels at the AV crossing site or around the macular region in all of the other eyes of both groups., Conclusions: Both AV sheathotomy and simple PVD significantly reduced macular edema associated with BRVO. However, there was no significant difference in the improvement of macular function following either procedure. Postoperative improvement of retinal circulation by either reperfusion of the occluded vein or collateral vessel formation was found. This accounted for functional and morphologic improvements.

Purpose: We quantitatively evaluated the effects of arteriovenous (A/V) crossing sheathotomy on retinal circulation in patients with branch retinal vein occlusion (BRVO) accompanied by macular edema., Design: Interventional case series., Methods: In 18 consecutive patients (18 eyes) with BRVO accompanied by macular edema who underwent A/V crossing sheathotomy between August 1999 and April 2002, changes in retinal circulation after the surgery were evaluated by fluorescein videoangiography with a scanning laser ophthalmoscope and by image analysis using dye dilution technique. At a venule distal to the responsible A/V crossing site and a normal venule, the circulation time (T50) from the beginning of filling to 50% filling of the peak intensity was calculated. The time difference (DeltaT50) between T50 at the point on the affected venule and that at the point on the normal venule, which represents the filling delay at the venule distal to the A/V crossing site, was compared between before and early after the surgery., Results: The preoperative DeltaT50 was 1.36 +/- 1.15 seconds (mean +/- SD), and the postoperative DeltaT50 was 0.72 +/- 0.77 seconds (P =.035, paired t test). In 11 of the 18 eyes, DeltaT50 decreased by 20% or more after the surgery. In the other 7 eyes, DeltaT50 was unchanged or slightly increased after the surgery., Conclusions: Although a randomized controlled study is needed to confirm the effectiveness of A/V crossing sheathotomy on visual function, this technique could be effective for improving the delay in perfusion in the affected venule.

A new family of poly(anhydrides) (PA) has been developed which can be cured photochemically to produce degradable networks. These degradable anhydride networks may be useful in orthopaedics as bone cements and as matrices for drug delivery. This system, which is a semi-interpenetrating network (semi-IPN), has been evaluated for biocompatibility in subcutaneous tissue in rats and appears to undergo degradation primarily by surface erosion. The inflammatory response to the semi-IPN implants was minimal at both short (3 and 6 weeks) and long (28 weeks) time points and the fibrotic response was largely absent throughout the duration of this study. Furthermore, the OrthoCure implant material integrated well with the surrounding tissue and was invaded with vascularized connective tissue. For reference, linear PA controls were tested and showed a foreign body response culminating in the formation of relatively avascular fibrous capsule several cell layers thick, which became thicker over time, a response similar to what is typically observed in FDA approved implantable polymeric device systems.

Purpose: To report arteriovenous adventitial sheathotomy for treatment of macular edema associated with branch retinal vein occlusion., Methods: Case reports with review. Five eyes of five patients with best-corrected visual acuity of less than 20/200 secondary to branch retinal vein occlusion had pars plana vitrectomy and arteriovenous adventitial sheathotomy and were followed postoperatively for a mean of 6.5 years (range, 5 to 7 years)., Results: In four of five eyes, the best-corrected visual acuity improved to 20/30 to 20/70. In the remaining eye, visual acuity remained at finger counting secondary to macular ischemia., Conclusion: Arteriovenous adventitial sheathotomy may be beneficial for select patients with poor vision secondary to branch retinal vein occlusion.

The recently developed X-ray scanning analytical microscope (XSAM) was applied for the analysis of the soft tissue of rat in which Ni was implanted and serious inflammation occurred. Our aim is to investigate the relationship between tissue response and elemental distributions. The XSAM observation was conducted in air without pretreatment and staining of samples. Mapping images of P, S, Ca, Fe and Ni, which were the elements with low concentration in soft tissue, were obtained from the soft tissue blocks of rat where Ni was implanted. S mapping image showed the localization of S in muscle and in hairs. Ca mapping image showed the localization of Ca in muscle and hair roots. Fe distribution was also observed and the localized area was consistent with the hemorrhagic area. The Ni dissolution area was clearly detected around the Ni implant. Comparison with the histological observation showed that the Ni dispersed area was consistent with the inflammatory area and the degree of tissue damage was closely related to the dissolved Ni concentration.

Soft tissue reactions to two materials of different microstructure made with porous and dense hydroxyapatite ceramic granules, were compared in this study. Each was implanted subcutaneously in the abdomen of 10 dogs. The implants were removed 1, 3 and 6 months after implantation, and examined by light microscopy. Heterotopic bone formation was only evident around porous hydroxyapatite ceramic granules in 6 of the 10 animals after 3 months, and in all cases after 6 months, but never around dense granules. These findings suggested that cellular differentiation and induction of osteogenesis may be influenced by the physical and chemical factors in the micromilieu provided by porous hydroxyapatite ceramic granules.

In this paper, the formation of a granuloma following subcutaneous implantation of beta-whitlockite powder is described. The implants were removed after 3, 5 and 7 wk and examined histologically. In the granuloma giant cells, macrophages, lymphocytes and plasma cells are present. The presence of plasma cells indicates that not only inflammation occurs, but that an immunoresponse also takes place. Resorption and phagocytosis of particles was observed and the particles were found in the regional lymph nodes after 7 wk. beta-Whitlockite powder induces an inflammation and both a cellular and a humoral immunological response, when implanted subcutaneously.