[Perioperative antibiotics in the management of hand infection]. / Antibiothérapie périopératoire dans les infections de la main.

PURPOSE: There is no consensus on the utility of postoperative antibiotherapy in hand infections after surgical management. The aim of this study was to evaluate if the absence of postoperative antibiotic therapy was detrimental after surgical treatment. METHODS: We included 287 patients operated on for a hand infection between January 2018 and October 2023. Preoperative or postoperative antibiotic prescription was collected for every patient. Patients cured for their infection with a single surgery were classified as "simple evolution", while patients requiring repetitive surgery or who had at least one complication directly linked to the initial infection (extension of infection or necrosis) were considered "complicated". RESULTS: From a total of 287 patients, we included 188 paronychia, 40 phlegmons, 47 abscesses and 12 superinfected wounds. The revision surgery rate was 9.4%, and the complication rate was 27.2%. One hundred and seventeen (40.8%) patients received preoperative antibiotic therapy from emergency physicians or general practitioners, among whom a complication rate of 31.6% was observed. The causal link did not reach the significance threshold for the whole group of patients (P=0.079). However, preoperative antibiotic use in phlegmon patients was directly correlated with the occurrence of at least one complication (P=0.032). In all, 82.9% of patients did not require postoperative antibiotic therapy, 95% of whom had an uncomplicated course. CONCLUSIONS: Preoperative probabilistic antibiotic therapy is an independent risk factor for complications, particularly if given at a collected stage. Antibiotics should not be routinely prescribed postoperatively in a correct debridement is performed. We recommend that antibiotics be used only in very specific cases (osteitis, arthritis, necrosis and/or high-risk patients).

[Granular cells tumour (Abrikossof) of the ulnar nerve at the arm. A case report and literature review]. / Tumeur d'Abrikossof (tumeur à cellules granuleuses) du nerf ulnaire au bras. À propos d'un cas et revue de la littérature des tumeurs à cellules granuleuses du nerf ulnaire.

INTRODUCTION: Granular cell tumours are extremely rare on peripheral nerves, with an incidence of 0.029% of pathologic samples. In a literature review, we found only 5 cases involving the ulnar nerve, although considered the most frequently involvement nerve. CASE REPORT: A 32 year-old female from the French West Indies presented a severe arm pain with deficit of interosseous hand muscles. Imaging studies were in favour of a Schwanoma, but during surgery, we found an unremovable intra-neural tumour. Nerve biopsy revealed a granular cell tumour. Initial decision was observation only. However, within two years, tumour increased in size, along with pain aggravation and functional deficit. We performed a nerve resection (with adequate margins) with reconstruction using sural nerve graft associated with a neurotisation of the motor branch with the anterior interosseus nerve. At two years follow-up, no recurrence was observed. The scar is hypersensitive with moderate neuropathic pain. There is a sensory reinnervation of the fourth finger, with no motor recovery of the hand. We observed a slight recovery of flexor profundus tendons, which, in turn increased the claw hand. DISCUSSION: The five cases described in the literature were managed differently (biopsy only, excision, excision with reconstruction), with modest results. There is no recommended treatment. Our case is the first at arm level. We were able to perform complete resection, but functional result is poor. CONCLUSION: Granular cell tumours require treatment if symptomatic (pain, function loss), but, at the moment, there is no recommended treatment.

Histology and Biaxial Mechanical Behavior of Abdominal Aortic Aneurysm Tissue Samples.

Abdominal aortic aneurysms (AAAs) represent permanent, localized dilations of the abdominal aorta that can be life-threatening if progressing to rupture. Evaluation of risk of rupture depends on understanding the mechanical behavior of patient AAA walls. In this project, a series of patient AAA wall tissue samples have been evaluated through a combined anamnestic, mechanical, and histopathologic approach. Mechanical properties of the samples have been characterized using a novel, strain-controlled, planar biaxial testing protocol emulating the in vivo deformation of the aorta. Histologically, the tissue ultrastructure was highly disrupted. All samples showed pronounced mechanical stiffening with stretch and were notably anisotropic, with greater stiffness in the circumferential than the axial direction. However, there were significant intrapatient variations in wall stiffness and stress. In biaxial tests in which the longitudinal stretch was held constant at 1.1 as the circumferential stretch was extended to 1.1, the maximum average circumferential stress was 330 ± 70 kPa, while the maximum average axial stress was 190 ± 30 kPa. A constitutive model considering the wall as anisotropic with two preferred directions fit the measured data well. No statistically significant differences in tissue mechanical properties were found based on patient gender, age, maximum bulge diameter, height, weight, body mass index, or smoking history. Although a larger patient cohort is merited to confirm these conclusions, the project provides new insight into the relationships between patient natural history, histopathology, and mechanical behavior that may be useful in the development of accurate methods for rupture risk evaluation.

Scaling of caterpillar body properties and its biomechanical implications for the use of a hydrostatic skeleton.

Caterpillars can increase their body mass 10,000-fold in 2 weeks. It is therefore remarkable that most caterpillars appear to maintain the same locomotion kinematics throughout their entire larval stage. This study examined how the body properties of a caterpillar might change to accommodate such dramatic changes in body load. Using Manduca sexta as a model system, we measured changes in body volume, tissue density and baseline body pressure, and the dimensions of load-bearing tissues (the cuticle and muscles) over a body mass range from milligrams to several grams. All Manduca biometrics relevant to the hydrostatic skeleton scaled allometrically but close to the isometric predictions. Body density and pressure were almost constant. We next investigated the effects of scaling on the bending stiffness of the caterpillar hydrostatic skeleton. The anisotropic non-linear mechanical response of Manduca muscles and soft cuticle has previously been quantified and modeled with constitutive equations. Using biometric data and these material laws, we constructed finite element models to simulate a hydrostatic skeleton under different conditions. The results show that increasing the internal pressure leads to a non-linear increase in bending stiffness. Increasing the body size results in a decrease in the normalized bending stiffness. Muscle activation can double this stiffness in the physiological pressure range, but thickening the cuticle or increasing the muscle area reduces the structural stiffness. These non-linear effects may dictate the effectiveness of a hydrostatic skeleton at different sizes. Given the shared anatomy and size variation in Lepidoptera larvae, these mechanical scaling constraints may implicate the diverse locomotion strategies in different species.

Advanced finger infection: more frequent than expected and mostly iatrogenic.

Some patients present at an advanced stage of their fingertip infection with an extension of the infection in anatomical spaces or into fragile structures. One hundred and twenty-five patients have been operated on for a finger infection. Forty-one patients (33%) have been treated at the "complication" stage, while 84 cases (67%) were considered "non-complicated". The delay between initial injury and the surgical treatment was 12 days in the "non-complicated" group versus 30 in the "complication" group (p < 0.001). Osteitis (39% of the complications), and flexor sheath infection (37%) were the most frequent complications. Prescribing preoperative antibiotics increases the risk of being in the "complicated" group at p = 0.09. One hundred and thirteen patients (90.4%) were cured of their infection after a single operation. Neither the cause of infection, nor the type of germ or associated diabetes increased the risk of complication in our series. A better education of the first interveners (general practitioner or emergency doctor) in hand infection care could reduce the rate of complication allowing a faster access to hand surgeons.

Soft-cuticle biomechanics: a constitutive model of anisotropy for caterpillar integument.

The mechanical properties of soft tissues are important for the control of motion in many invertebrates. Pressurized cylindrical animals such as worms have circumferential reinforcement of the body wall; however, no experimental characterization of comparable anisotropy has been reported for climbing larvae such as caterpillars. Using uniaxial, real-time fluorescence extensometry on millimeter scale cuticle specimens we have quantified differences in the mechanical properties of cuticle to circumferentially and longitudinally applied forces. Based on these results and the composite matrix-fiber structure of cuticle, a pseudo-elastic transversely isotropic constitutive material model was constructed with circumferential reinforcement realized as a Horgan-Saccomandi strain energy function. This model was then used numerically to describe the anisotropic material properties of Manduca cuticle. The constitutive material model will be used in a detailed finite-element analysis to improve our understanding of the mechanics of caterpillar crawling.

Muscle performance in a soft-bodied terrestrial crawler: constitutive modelling of strain-rate dependency.

Experimental data on the passive mechanical properties of the ventral interior lateral muscle of the tobacco hornworm caterpillar, Manduca sexta, are reported. The stress-deformation response of the Manduca muscle is shown to be nonlinear pseudo-elastic, capable of large deformations and subject to stress softening during initial loading cycles. The muscle passive mechanical properties also depend on multiple time-dependent processes. In particular, we show new experimental data from cyclic loading tests of an unstimulated muscle with constant maximum stretch and different, constant engineering strain rates. Then, on the basis of these data a constitutive model is derived to reproduce the main characteristics of this behaviour. In formulating the constitutive model, we consider the muscle as a complex macromolecular structure with fibrous components at numerous size scales. The model uses a phenomenological approach to account for different mechanisms by which passive force changes during applied deformation and how the muscle properties recover after unloading.

A constitutive model for muscle properties in a soft-bodied arthropod.

In this paper, we examine the mechanical properties of muscles in a soft-bodied arthropod under both passive and stimulated conditions. In particular, we examine the ventral interior lateral muscle of the tobacco hornworm caterpillar, Manduca sexta, and show that its response is qualitatively similar to the behaviour of particle-reinforced rubber. Both materials are capable of large nonlinear elastic deformations, show a hysteretic behaviour and display stress softening during the first few cycles of repeated loading. The Manduca muscle can therefore be considered as different elastic materials during loading and unloading and is best described using the theory of pseudo-elasticity. We summarize the basic equations for transversely isotropic pseudo-elastic materials, first for general deformations and then for the appropriate uniaxial specialization. The constitutive relation proposed is in good agreement with the experimental data for both the passive and the stimulated conditions.

Preimplantation genetic diagnosis for spinal muscular atrophy type I.

OBJECTIVE: Couples with children who have spinal muscular atrophy type I (SMA) face a 25% risk of having affected offspring with spontaneous conception. Preimplantation genetic testing (PGT) is possible for the deletions in the survival motor neuron (SMN) gene that have been identified in 98% of SMA type I cases. PGT would provide new reproductive options for families at risk for SMA. METHODS: Three couples with previously affected children confirmed by DNA testing each underwent in vitro fertilization (IVF) and PGT of the resulting embryos. One or two blastomeres were biopsied from each embryo and analyzed for deletions in exons 7 and 8 of the SMN gene. RESULTS: Nine embryos were predicted to be unaffected, three to be affected, and one embryo could not be interpreted. One of three patients receiving transfer of unaffected embryos became pregnant with twins. CONCLUSIONS: Preimplantation genetic testing provides a means for couples at risk for spinal muscular atrophy type I to reduce their chance of initiating an affected pregnancy.

Mental retardation and Ullrich-Turner syndrome in cases with 45,X/46X,+mar: additional support for the loss of the X-inactivation center hypothesis.

Four cases having mosaicism for a small marker or ring [45,X/46,X,+mar or 45,X/46,X,+r] chromosome were ascertained following cytogenetic studies requested because of minor anomalies (cases 1, 3, and 4) and/or short stature (cases 2 and 4). While all 4 cases had traits typical of Ullrich-Turner syndrome (UTS), cases 1, 3, and 4 had manifestations not usually present in UTS, including unusual facial appearance, mental retardation/developmental delay (MR/DD) (cases 3 and 4), and syndactylies (case 1). The facial appearances of cases 1 and 3 were similar yet distinct from that of case 4. Using fluorescence in situ hybridization (FISH), each of the markers in these 4 cases was identified as having been derived from an X chromosome. The level of mosaicism for the mar/r(X) cell line in these cases varied from 70% (case 1) to 16% (case 4) but was not apparently correlated with the presence of MR/DD. Replication studies demonstrated a probable early replication pattern for the mar/r(X) in cases 1, 3, and 4, while the marker in case 2 was apparently late replicating. To date, 41 individuals having mosaicism for a small mar/r(X) chromosome have been described. Interestingly, most of the 14 individuals having a presumedly active mar/r(X) demonstrated clinical findings atypical of UTS, including abnormal facial changes (11) and MR/DD (13). MR was noted most frequently in those cases having at least 50% mosaicism for the marker or ring. In contrast, atypical UTS facial appearance or MR/DD was not noted in 14 of the 16 cases with UTS who carried a probable late replicating marker or ring. In conclusion, although the phenotype of 45,X/46,X,mar/r(X) individuals appears to be influenced by the genetic content and degree of mosaicism for the mar/r(X), the most significant factor associated with MR/DD appears to be the activity status of the mar/r(X) chromosome. Thus, our 4 cases provide further support for the hypothesis that a lack of inactivation of a small mar/r(X) chromosome may be a factor leading to the MR and other phenotypic abnormalities seen in this subset of individuals having atypical UTS.