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Introduction: Little is known about the perioperative management of Pediculus capitis (lice) infestations, including risk of contamination to the sterile field, whether to delay surgery, and optimal time to treat and/or operate. Case Report: Two identical twin patients presented for elective in situ percutaneous pinning of chronic slipped capital femoral epiphyses. Active pediculosis capitis was noted intraoperatively by the anesthesia team during the first patient's surgery. Meticulous examination of the sterile field at that time demonstrated no organisms or other sources of contamination. The second patient's surgery was delayed to discuss her case with the infectious disease team. Scant literature exists to guide recommendations. Ultimately, a single permethrin treatment immediately before surgery was recommended and followed by our team. After careful prepping and draping, a louse was observed on the sterile field near the planned pin insertion site. The case was immediately canceled and delayed indefinitely. After two additional treatments over the next 4 days, only eggs (but no active insects) were observed in the patient's hair. We elected to proceed to surgery at that time, which concluded without issue. Conclusion: The surgical implications of an active lice infestation are numerous. Administration of antiparasitic medication in the immediate pre-operative period causes increased movement in pediculosis capitis, which may increase risk of sterile field contamination. Elective procedures should be postponed to complete multiple rounds of permethrin. In cases of urgent/emergent surgery, or in which treatment delay is unfeasible, foregoing delousing treatment in the immediate pre-operative period may be recommended.
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PURPOSE: Late presentation of hip dysplasia persists despite robust screening methods. After 6 months of age, treatment with a hip abduction orthosis becomes challeng-ing, and all other treatment modalities have higher reported rates of complications. METHODS: We performed a retrospective review of all patients from 2003 to 2012 who had the sole diagnosis of de-velopmental hip dysplasia, who presented before 18 months of age, and who had at least 2 years of follow-up. The cohort was then grouped based on their presentation before (BSM) or after (ASM) 6 months of age. The groups were compared for demographics, exam findings, and outcomes. RESULTS: We identified 36 patients with presentation after 6 months and 63 patients who presented before 6 months. Hav-ing a normal newborn hip exam and unilateral involvement were risk factors for late presentation (p < 0.001). Only 6% (2/36) patients in the ASM group were successfully treated non-operatively; the ASM group underwent an average of 1.33 procedures. The odds of utilizing an open reduction for the primary procedure for the late presenting patient was 4.91 times higher than the early presenting group (p = 0.001). Limited hip range of motion, particularly hip external rotation, was the only significantly different out-come (p = 0.03). There was no significance difference in the complications (p = 0.24). CONCLUSION: Management of patients with developmental hip dysplasia presenting after 6 months of age requires more surgical intervention but can result in satisfactory outcomes.
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Displasia do Desenvolvimento do Quadril , Luxação Congênita de Quadril , Luxação do Quadril , Recém-Nascido , Humanos , Lactente , Luxação Congênita de Quadril/diagnóstico por imagem , Luxação Congênita de Quadril/terapia , Aparelhos Ortopédicos , Fatores de Risco , Estudos Retrospectivos , Resultado do TratamentoRESUMO
PURPOSE: Atypical skeletal development is common in youth with myelomeningocele (MM), though the underlying reasons have not been fully elucidated. This study assessed skeletal maturity in children and adolescents with MM and examined the effects of sex, age, sexual development, ethnicity, anthropometrics and shunt status. METHODS: Forty-three males and 35 females with MM, 6-16 years old, underwent hand radiographs for bone age determination. The difference between bone age and chronological age was evaluated using Wilcoxon sign rank tests. Relationships between age discrepancy (skeletal-chronological) and participant characteristics were assessed using multiple linear regression with forward selection. RESULTS: Overall, forty percent (31/78) of MM participants had an advanced bone age of 1 year or greater (median: 2.5 years), while 47% (37/78) were within 1 year above or below their chronological age (-0.001 years) and 13% (10/78) were delayed by more than 1 year (-1.4 years). Bone age was advanced compared to chronologic age in both males and females (p⩽ 0.024). Advanced bone age was observed in early to late puberty and after maturation (p⩽ 0.07), as well as in Hispanic participants (p= 0.003) and in those with a shunt (p= 0.0004). Advanced bone age was positively correlated with height, weight and body mass index (BMI) percentiles (p= 0.004). In multiple linear regression analysis, advanced bone age was most strongly associated with higher Tanner stage of sexual development, and higher weight, height or BMI percentile. CONCLUSIONS: Advanced skeletal maturity is common in children/adolescents with MM over 8 years of age who have reached puberty (65%), particularly those who are overweight (80%). Hormonal effects associated with adiposity and sexual maturity likely influence skeletal maturation. Clinicians may use Tanner stage and weight or BMI to gain insight into skeletal maturity.
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Determinação da Idade pelo Esqueleto , Meningomielocele/fisiopatologia , Adolescente , Fatores Etários , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Meningomielocele/diagnóstico por imagem , Estudos Prospectivos , Fatores Sexuais , Maturidade SexualRESUMO
A finite element model was used to investigate the counter-intuitive experimental observation that some regions of the aponeuroses of a loaded and contracting muscle may shorten rather than undergo an expected lengthening. The model confirms the experimental findings and suggests that pennation angle plays a significant role in determining whether regions of the aponeuroses stretch or shorten. A smaller pennation angles (25 degrees ) was accompanied by aponeurosis lengthening whereas a larger pennation angle (47 degrees ) was accompanied by mixed strain effects depending upon location along the length of the aponeurosis. This can be explained by the Poisson effect during muscle contraction and a Mohr's circle analogy. Constant volume constraint requires that fiber cross sectional dimensions increase when a fiber shortens. The opposing influences of these two strains upon the aponeurosis combine in proportion to the pennation angle. Lower pennation angles emphasize the influence of fiber shortening upon the aponeurosis and thus favor aponeurosis compression, whereas higher pennation angles increase the influence of cross sectional changes and therefore favor aponeurosis stretch. The distance separating the aponeuroses was also found to depend upon pennation angle during simulated contractions. Smaller pennation angles favored increased aponeurosis separation larger pennation angles favored decreased separation. These findings caution that measures of the mechanical properties of aponeuroses in intact muscle may be affected by contributions from adjacent muscle fibers and that the influence of muscle fibers on aponeurosis strain will depend upon the fiber pennation angle.
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Análise de Elementos Finitos , Modelos Biológicos , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Animais , HumanosRESUMO
Many of those who survive a stroke develop a gait disability known as stiff-knee gait (SKG). Characterized by reduced knee flexion angle during swing, people with SKG walk with poor energy efficiency and asymmetry due to the compensatory mechanisms required to clear the foot. Previous modeling studies have shown that knee flexion activity directly before the foot leaves the ground, and this should result in improved knee flexion angle during swing. The goal of this research is to physically test this hypothesis using robotic intervention. We developed a device that is capable of assisting knee flexion torque before swing but feels imperceptible (transparent) for the rest of the gait cycle. This device uses sheathed Bowden cable to control the deflection of a compliant torsional spring in a configuration known as a Series Elastic Remote Knee Actuator (SERKA). In this investigation, we describe the design and evaluation of SERKA, which includes a pilot experiment on stroke subjects. SERKA could supply a substantial torque (12 N· m) in less than 20 ms, with a maximum torque of 41 N·m. The device resisted knee flexion imperceptibly when desired, at less than 1 N·m rms torque during normal gait. With the remote location of the actuator, the user experiences a mass of only 1.2 kg on the knee. We found that the device was capable of increasing both peak knee flexion angle and velocity during gait in stroke subjects. Thus, the SERKA is a valid experimental device that selectively alters knee kinetics and kinematics in gait after stroke.
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Due to the well-described spring-mass dynamics of bouncing gaits, human hopping is a tractable model for elucidating basic neuromuscular compensation principles. We tested whether subjects would employ a multi-joint or single-joint response to stabilize leg stiffness while wearing a spring-loaded ankle-foot orthosis (AFO) that applied localized resistive and assistive torques to the ankle. We analyzed kinematics and kinetics data from nine subjects hopping in place on one leg, at three frequencies (2.2, 2.4, and 2.8Hz) and three orthosis conditions (freely articulating AFO, AFO with plantarflexion resistance, and AFO with plantarflexion assistance). Leg stiffness was invariant across AFO conditions, however, compensation strategy depended upon the nature of the applied load. Biological ankle stiffness increased in response to a resistive load at twice the rate that it decreased with an assitive load. Ankle adjustments alone fully compensated for an assistive load with no net change in combined (biological plus applied) total ankle stiffness (p > or =0.133). In contrast, a resistive load resulted in a 7.4-9.0% increase in total ankle stiffness across frequencies and a concomitant 10-15% increase in knee joint stiffness at each frequency (p< or =0.037). The increased knee joint stiffness in response to resistive ankle load allowed subjects to maintain a more flexed knee at mid-stance, which attenuated the effect of the increased total ankle joint stiffness to preserve leg stiffness and whole limb biomechanical performance. Our findings suggest humans maintain invariant leg stiffness in bouncing gaits through different intralimb compensation strategies that are specific to the nature of the joint loading.