Clinical diagnosis of syndesmotic ankle instability: evaluation of stress tests behind the curtains

We studied the feasibility of clinical tests in the diagnosis of syndesmotic injury of the ankle. 9 investigators examined 12 persons twice, including 2 patients with an arthroscopically-confirmed syndesmotic injury. They sat behind a curtain that exposed only the lower legs. We found a statistically significant relation between the final arthroscopic diagnosis and the squeeze, fibula translation, Cotton, and external rotation tests as well as for limited dorsal flexion. None of the syndesmotic tests was uniformly positive in chronic syndesmotic injury. The external rotation test had the fewest false-positive results, the fibula translation test the most. The external rotation test had the smallest inter-observer variance. The physical diagnosis was missed in one fifth of all examinations. When in accordance with medical history and physical examination, positive stress tests should raise a high index of suspicion of syndesmotic instability. The final diagnosis of such instability, however, should be made by additional diagnostic imaging and/or arthroscopy.     

Differential Effect of Diarrhea on FK506 Versus Cyclosporine A Trough Levels and Resultant Prevention of Allograft Rejection in Renal Transplant Recipients

Diarrhea is the most frequently reported adverse event in patients treated with mycophenolate mofetil. Twenty-six renal transplant patients on a mycophenolate mofetil-based immunosuppressive regime with persistent afebrile diarrhea were examined. Diarrhea caused a significant rise in FK-506 trough levels despite intake of stable doses, necessitating FK-506 dose reductions of 30% to obtain pre-diarrhea trough levels. In contrast, trough levels of cyclosporine A remained stable without dose adjustments. This suggests that absorption and/or metabolism is differentially altered for FK506 compared with cyclosporine A in patients with diarrhea. In nine patients mycophenolate mofetil was reduced or stopped because of persistent diarrhea without identifiable cause. This resulted in end-stage renal disease because of chronic rejection in two patients, and in acute rejection in two patients, all taking FK506 and steroids. Therefore, dose adjustments of FK506 in patients with diarrhea must be carefully monitored, especially when doses of mycophenolate mofetil are also reduced.     

Reduced tonicity stimulates an inflammatory response in nucleus pulposus tissue that can be limited by a COX‐2‐specific inhibitor

In intervertebral disc herniation with nucleus pulposus (NP) extrusion, the elicited inflammatory response is considered a key pain mechanism. However, inflammatory cytokines are reported in extruded herniated tissue, even before monocyte infiltration, suggesting that the tissue itself initiates the inflammation. Since herniated tissue swells, we investigated whether this simple mechanobiological stimulus alone could provoke an inflammatory response that could cause pain. Furthermore, we investigated whether sustained‐release cyclooxygenase‐2 (COX2) inhibitor would be beneficial in such conditions. Healthy bovine NP explants were allowed to swell freely or confined. The swelling explants were treated with Celecoxib, applied either as a bolus or in sustained‐release. Swelling explants produced elevated levels of interleukin‐6 (IL‐6) and prostaglandin E₂ (PGE₂) for 28 days, while confined explants did not. Both a high concentration bolus and 10 times lower concentration in sustained release completely inhibited PGE₂ production, but did not affect IL‐6 production. Swelling of NP tissue, without the inflammatory system response, can trigger cytokine production and Celecoxib, even in bolus form, may be useful for pain control in extruded disc herniation. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1724–1731, 2015.     

Perceval Sutureless Aortic Valve Implantation: Midterm Outcomes

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Contribution of collagen network features to functional properties of engineered cartilage

BACKGROUND: Damage to articular cartilage is one of the features of osteoarthritis (OA). Cartilage damage is characterised by a net loss of collagen and proteoglycans. The collagen network is considered highly important for cartilage function but little is known about processes that control composition and function of the cartilage collagen network in cartilage tissue engineering. Therefore, our aim was to study the contribution of collagen amount and number of crosslinks on the functionality of newly formed matrix during cartilage repair. METHODS: Bovine articular chondrocytes were cultured in alginate beads. Collagen network formation was modulated using the crosslink inhibitor beta-aminopropionitrile (BAPN; 0.25mM). Constructs were cultured for 10 weeks with/without BAPN or for 5 weeks with BAPN followed by 5 weeks without. Collagen deposition, number of crosslinks and susceptibility to degradation by matrix metalloproteinase-1 (MMP-1) were examined. Mechanical properties of the constructs were determined by unconfined compression. RESULTS: BAPN for 5 weeks increased collagen deposition accompanied by increased construct stiffness, despite the absence of crosslinks. BAPN for 10 weeks further increased collagen amounts. Absence of collagen crosslinks did not affect stiffness but ability to hold water was lower and susceptibility to MMP-mediated degradation was increased. Removal of BAPN after 5 weeks increased collagen amounts, allowed crosslink formation and increased stiffness. DISCUSSION: This study demonstrates that both collagen amounts and its proper crosslinking are important for a functional cartilage matrix. Even in conditions with elevated collagen deposition, crosslinks are needed to provide matrix stiffness. Crosslinks also contribute to the ability to hold water and to the resistance against degradation by MMP-1.     

Combined traumatic occiput-C1 and C1-C2 dissociation: 2 case reports

Occiput-C1 and C1-C2 dissociations and dislocations have been well documented in the literature. However, after thorough review of the literature, we found very little in the literature regarding combined occiput-C1 and C1-C2 dissociations in adults who survived. We present 2 case reports describing the clinical presentation, initial management, operative treatment, and postoperative course of 2 patients who sustained traumatic combined occiput-C1 and C1-C2 dissociations. After initial stabilization, both patients underwent open reduction and posterior occipital-cervical fusion with segmental fixation. At recent follow-up, both patients maintain good sagittal alignment without loss of reduction, and they have radiographic progression to fusion, minimal pain, and improved neurologic function. Combined occiput-C1 and C1-C2 dissociations are rare but serious injuries. Incomplete dissociations may not be evident on initial radiographs. Computed tomography or magnetic resonance imaging is recommended for formal diagnosis. A traumatic dural tear may be present. We recommend open reduction and posterior occipital-cervical fusion with segmental fixation for these patients.     

Optimizing the performance of the feedback controller for state-based switching bilinear systems

This article is concerned with the design and performance optimization of feedback controllers for state-based switching bilinear systems (SBLSs), where subsystems take the form of bilinear systems in different state space polyhedra. First, by further dividing the subregions into smaller regions and designing region-dependent feedback controllers in the resulting regions, the SBLSs can be transformed into corresponding switching linear systems (SLSs). Then, for these SLSs, by imposing contractility conditions on the Lyapunov functions, an upper bound on the infinite horizon quadratic cost can be obtained. Optimizing this upper bound yields the controller design. The optimization problem is formulated as a linear matrix inequalities optimization problem, which can be solved efficiently. Finally, the stability of the close-loop system under the proposed controller is established step by step through a decreasing overall Lyapunov function.     

Long-term bonding to eroded dentin requires superficial bur preparation

Objectives

This study aims to evaluate the influence of different surface preparation techniques on long-term bonding effectiveness to eroded dentin.

Materials and methods

Dentin specimens were eroded by pH cycling or were left untreated as control, respectively. Five different “preparation” techniques were applied: (1) cleaning with pumice, (2) air abrasion, (3) silicon polisher, (4) proxo-shape, and (5) diamond bur. The three-step etch-and-rinse adhesive OptiBond FL (O-FL; Kerr) and the mild two-step self-etch adhesive Clearfil SE Bond (C-SE; Kuraray) were evaluated. Micro-tensile bond strength was measured after water storage for 24?h and 1?year. Fracture analysis was performed by stereomicroscopy and SEM. Interfaces were characterized by TEM. Differences were statistically analyzed with a linear mixed effects model (α?=?0.05).

Results

Erosion reduced bond strength in all groups, but this effect was less prominent when eroded dentin was prepared by diamond bur. Storage lowered bond strength in almost all groups significantly, but this ageing effect was more prominent for the eroded surfaces than for non-eroded controls. Whereas after 1-year control specimens revealed superior bond strength with the three-step etch-and-rinse adhesive (O-FL), the mild two-step self-etch adhesive (C-SE) revealed a better 1-year bond strength to eroded dentin. The interface at eroded dentin appeared very prone to degradation as was shown by the increased amount of adhesive failures and by the silver infiltration detected by TEM.

Conclusions and clinical relevance

Although a minimally invasive approach should clinically always be strived for, superficial preparation (or minimal roughening) with a diamond bur is recommendable for long-term bonding to eroded dentin.     

Acanthoma supratrochantericum.

We report the cases of five patients with lesions of benign reactive hyperplasia of the skin in the hip joint region. In view of the distinct clinical features, and in analogy with previously reported cases of acanthoma fissuratum, we termed this condition acanthoma supratrochantericum.     

Pseudoxanthoma elasticum with generalized retinal dysfunction, a common finding?

PURPOSE: Pseudoxanthoma elasticum (PXE; [MIM 264800]) is an autosomal recessive systemic disorder characterized by progressive degeneration and calcification of elastic fibers in connective tissue. The phenotype is variable, with cutaneous, vascular, and ophthalmic abnormalities. The disorder is a consequence of mutations in the ABCC6 gene. Visual impairment is mainly due to neovascular complications, and retinal function is usually assumed to be normal. The purpose of this study was the objective assessment of macular and generalized retinal function in unrelated patients with clinical and/or genetic features of PXE. METHODS: Four unrelated patients carrying a clinical diagnosis of PXE presented with unexplained visual loss. After ophthalmic examination, retinal and macular function was assessed by full-field electroretinogram (ERG) and pattern ERG, respectively, according to ISCEV (International Society for Clinical Electrophysiology of Vision) recommendations. Molecular analysis of the ABCC6 gene was performed in three patients by dHPLC (denaturing high-performance liquid chromatography) and direct sequencing. RESULTS: Full-field ERG revealed significant reduction of cone and rod responses in all four patients. Funduscopic appearances varied. Three patients were found to carry ABCC6 mutations. In case 1, a novel nonsense mutation (p.L1474X) was detected in exon 31 paired with a splice-site mutation. Mutation analyses in cases 3 and 4 revealed previously reported ABCC6 mutations. CONCLUSIONS: These findings suggest that retinal dysfunction in PXE may not be uncommon. The mechanism underlying retinal dysfunction is unknown but may result from metabolic disturbance leading to retinal toxicity with a possible role of modifying genetic or environmental factors rather than specific ABCC6 mutations.