钛基植入体用生物陶瓷涂层研究进展

本文总结了现有的钛合金植入体用生物陶瓷涂层材料和涂层制备方法。并针对生物陶瓷涂层在制备过程和临床应用中存在的界面结合强度以及化学稳定性差的问题,阐述了可行的解决方案,包括梯度涂层、复合涂层、掺杂改性和参数改进等。     

The effectiveness of mental imagery for improving strength in an asymptomatic population

Abstract

Background:

Strength training is one focus for physiotherapy management to help restore function. However, conventional strength training requiring an active muscular contraction is not always possible. Mental imagery (MI) has been proposed as a viable alternative to strength training without the need for actual movement.

Objective:

To investigate whether MI is effective in achieving strength gains in an asymptomatic population.

Methods:

A systematic review of key databases was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and risk of bias assessed using Grading of Recommendations Assessment, Development and Education (GRADE). Studies were included if they were a randomised control trial (RCT), clinical control trial (CCT) or pre-post study investigating the effect of an MI protocol for improving strength in asymptomatic adult populations.

Results:

From 639 articles, 28 full texts were assessed and six were included for review. These studied effect of MI on strength improvements for 5th finger abductors (n?=?53), quadriceps (n?=?51), elbow flexors (n?=?51), ankle dorsiflexors (n?=?51) and plantarflexors (n?=?51). Strength gains were reported in all muscle groups with the exception of elbow flexors. MI may be more effective for muscle groups with larger motor cortex representation, especially 5th finger abductors.

Conclusion:

The findings suggest that a course of MI can increase strength greater than a control group but less than a physical practice (PP) group within this population. The findings of this study provide promising clinical implications for use of MI for improvements or maintenance of strength within a patient group unable to actively strengthen due to pain or immobilisation.     

Effects of barium concentration on the radiopacity and biomechanics of bone cement: experimental study

Purpose  This study was undertaken to evaluate the changes in the radiopacity and mechanics of polymethylmethacrylate (PMMA) bone cement with the addition of barium. Materials and methods  Barium sulfate powder was added to a PMMA bone cement with an initial 10% barium concentration. The changes in radiopacity and strength were evaluated by testing cement blocks containing four barium concentrations (10%, 20%, 30%, 40%). Radiopacity was evaluated by measuring the computed tomography (CT) values of the bone cement, and strength was evaluated by compressive, three-point bending, and impact load tests. Results  CT values increased in proportion to the barium concentration. The compressive load test showed that cement with a 40% barium concentration was significantly more fragile than cement with lower barium concentrations. The three-point bending load test showed that the cement became more fragile in proportion to the barium concentration. The impact load test showed that cement with 30% and 40% barium concentrations was significantly more fragile than cement with 10% and 20% barium concentrations. Conclusion  Radiopacity is increased and strength is reduced by adding increasing concentrations of barium powder to bone cement. The results of the present study suggest that adding barium permits the radiopacity and strength of bone cement to be adjusted in clinical practice.     

Contributions of force and velocity to improved power with progressive resistance training in young and older adults

We investigated the effects of age on changes in the force and velocity components of knee extension (KE) power during 16 weeks of traditional progressive resistance training (PRT). Thirty-one young (27 ± 1 years, 16 men, 15 women) and 30 older (64 ± 1 years, 14 men, 16 women) adults trained by KE, leg press, and squat 3 days/week. PRT consisted of three sets with an appropriate load for 8–12 repetitions to fatigue. Testing occurred at baseline, 8, and 16 weeks. Thigh lean mass (TLM) was measured by DEXA. KE load–power and load–velocity curves were generated from peak concentric contractions against loads equivalent to 20, 30, 40, 50, and 60% maximum voluntary isometric contraction (MVC) force. Quadriceps neural activation relative to maximum was assessed during a sit-to-stand task. Participants increased KE 1RM (P < 0.05) by 8 weeks with young adults also increasing strength from 8 to 16 weeks. Adjusting for TLM, all groups increased KE specific strength (P < 0.05). MVC improved by 8 weeks in older adults and by 16 weeks in young subjects (P < 0.05). Neural activation requirements during standing and sitting declined in older adults by 8 weeks (P < 0.05). The KE load–power curve improved for all groups (P < 0.05) by 8 weeks with only young adults improving from 8 to 16 weeks. Peak concentric velocity increased only in older adults (P < 0.05). Training improvements in power resulted primarily from increases in strength both early and late for young adults while older adults realized early improvements in both strength and peak concentric velocity. Grants: This study was supported by National Institute on Aging Grant R01 AG017896 (MMB), Department of Veterans’ Affairs Merit Grant (MMB), and General Clinical Research Center Grant M01 RR00032.     

Variations in urine excretion of steroid hormones after an acute session and after a 4-week programme of strength training

Performing strength exercise, whether acutely or in a training programme, leads to alterations at the hypothalamic-pituitary-testicular and hypothalamic-pituitary-adrenal axes. One way to evaluate these changes is by analysis of the excretion of steroid hormones in the urine. The present study determined the variations in the urine profile of glucuroconjugated steroids after a single session of strength exercise and after a 4-week programme of strength training. The subjects were a group (n = 20) of non-sportsman male university students who worked out 3 days a week [Monday (M), Wednesday (W) and Friday (F)], performing the exercises at 70–75% of one repetition maximum strength (1-RM). Four urine samples were collected per subject: (A) before and (B) after a standard session prior to initiating the training programme, and (C) before and (D) after the same standard session at the end of the study, and they were assayed by gas chromatography coupled to mass spectrometry. The concentrations of the different hormones were determined relatively to the urine creatinine level (ng steroid/mg creatinine) to correct for diuresis. After the exercise sessions, both before and after the training programme, there was a fall in the urine excretion of androgens and estrogens, but no statistically significant changes in the excretion of tetrahydrocortisol (THF) and tetrahydrocortisone (THE). The anabolic/catabolic hormones ratio also decreased after the acute session, although only androstenodione + dehydroepiandrosterone (DHEA)/THE + THF ratio had a significant decrease (P < 0.05). After the training programme, there was a significant (P < 0.01) improvement in the strength of the muscle groups studied, and an increased urinary excretion of all the androgens with respect to the initial state of repose, with the difference being significant in the case of epitestosterone (Epit) (P < 0.05). The androsterone (A) + etiocholanolone (E)/THE + THF ratio increased significantly (P < 0.05) concerning the initial state. We therefore conclude that subjects suffer variations of the urine profile with regard to the steroid hormones before and after the acute strength sessions and after the training period. The alteration after the training programme seems to be due to the subjects’ hypothalamic-hypophysis-testicular and hypothalamic-pituitary-adrenal axes adaptations, which enable them to increase physical strength.     

Comparison of conventional resistance training and the fly-wheel ergometer for training the quadriceps muscle group in patients with unilateral knee injury

A fly-wheel ergometer (FWE) offering resistance training of the knee extensors has been designed for space travel and found to be effective during bed rest. The possibility exists that this device is also effective in training the knee extensors after knee injury. The purpose of this study was to compare the FWE to standard knee extensor training equipment for their effects on individuals with a history of knee injury, a group who commonly suffer from weakness of the knee extensors that effects their function. Twenty-nine subjects completed the study, which included tests of knee self-assessment, knee extensor static and dynamic muscle strength, size and neural activation as well as single leg power output, standing balance and vertical jump performance. Both groups showed statistically significant (P < 0.05) improvements in these variables over the 3-month training period but no differences were noted between the groups. The FWE appears to be as effective as standard resistance training equipment for improving knee extensor muscle group size and performance after knee injury.     

Is handgrip strength a marker of muscle and physical function of the lower limbs? Sex differences in older adults with obesity

Background and aimsIn this cross-sectional study we investigate the association between handgrip strength (HGS) and muscle function of the lower limbs and the predictors of the appendicular lean mass index (ALMI) in older adults with obesity of both sexes.Methods and resultsEighty-four older (67 ± 5 years) men (N = 44) and women (N = 40) with obesity (body mass index (BMI) 33 ± 4 kg/m²) performed: the HGS, isokinetic knee extensors (KE) and flexors (KF) muscle strength and power and Short Physical Performance Battery (SPPB). The correlation between HGS and lower limbs muscle function was evaluated, and four multiple hierarchical linear models were built to assess the contribution of each ALMI predictor (i.e., HGS, BMI, SPPB, muscle strength and power).In men, HGS was weakly-to-moderately associated (p < 0.05) with KE, KF muscle function and physical performance. In women, HGS showed a weak association (p < 0.05) with KE muscle function. The significant predictors of ALMI were only the BMI in women, whereas in the group of men BMI, KE maximal strength and power better explain the variance in ALMI than HGS alone.ConclusionOur results suggest that HGS should not be used alone as a marker of lower muscle nor physical function. Sex differences exist with the BMI that is a contributor of ALMI both in men and women. However, at least in the group of men, markers related to strength and power of the lower limbs can better describe variations in ALMI compared to HGS in this kind of population.Clinical trial registrationNA.     

Medium-intensity,high-volume “hypertrophic” resistance training did not induce improvements in rapid force production in healthy older men

The aim of the study was to determine whether it is possible to improve both maximum and rapid force production using resistance training that is typically used to induce muscle hypertrophy in previously untrained older men. Subjects (60–72 years) performed 20 weeks of “hypertrophic” resistance training twice weekly (n = 27) or control (n = 11). Maximum dynamic and isometric leg press, as well as isometric force over 0–100 ms, and maximum concentric power tests were performed pre- and post-intervention. Muscle activity was assessed during these tests by surface electromyogram of the vastus lateralis and medialis muscles. Muscle hypertrophy was assessed by panoramic ultrasound of the vastus lateralis. The intervention group increased their maximum isometric (from 2268 ± 544 to 2538 ± 701 N) and dynamic force production (from 137 ± 24 to 165 ± 29 kg), and these changes were significantly different to control (isometric 12 ± 16 vs. 1 ± 9 %; dynamic 21 ± 12 vs. 2 ± 4 %). No within- or between-group differences were observed in rapid isometric force or concentric power. Relative increases in vastus lateralis cross-sectional area trended to be statistically greater in the intervention group (10 ± 8 vs. 3 ± 6 %, P = 0.061). It is recommendable that resistance training programs for older individuals integrate protocols emphasizing maximum force/muscle hypertrophy and rapid force production in order to induce comprehensive health-related and functionally important improvements in this population.     

Are penile prostheses a viable option to recommend for gay men?

When talking to a gay men's prostate cancer support group on erectile dysfunction a question was asked of the author if he had evidence that a penile prosthesis would be rigid enough for anal sex. As a heterosexual male with no knowledge of a homosexual man with a prosthesis, the author could not answer the question. The local representative could not give the author a definitive answer either and there was no specific literature on this subject. However, testing of the rigidity of penile prosthesis demonstrated buckling forces of 800 g. On the basis of reported values that anal penetration requires 33% more rigidity than vaginal sex, the minimum rigidity required for vaginal sex is 500 g. Based on this figure a minimum rigidity of 634 mg is required for anal sex. A rigidity of 800 mg should therefore facilitate anal sex. This article considers current literature on the difference between heterosexual and homosexual prosthesis needs to aid health practitioners in decision‐making.