Enhanced somatosensory information decreases postural sway in older people

The somatosensory system plays an important role in balance control and age-related declines in somatosensory function have been implicated in falls incidence. Different types of insole devices have been developed to enhance somatosensory information and improve postural stability. However, they are often too complex and expensive to integrate into daily life and textured insole surfaces may provide an inexpensive and accessible means to enhance somatosensory input. This study investigated the effects of textured insole surfaces on postural sway in ten younger and seven older participants performing standing balance tests on a force plate under three insole surface conditions: (1) barefoot; (2) with hard; and (3), soft textured insole surfaces. With each insole surface, participants were tested under two vision conditions (eyes open, closed) on two standing surfaces (firm, foam). Four 30s trials were collected for different combinations of insole surface, standing surface and vision. Centre of pressure measurements included the range and standard deviation of anterior-posterior and medial-lateral displacement, path length and the 90% confidence elliptical area. Results revealed a significant Group*Surface*Insole interaction for five of the dependent variables. Compared to younger individuals, postural sway was greater in older people on both standing surfaces in the barefoot condition. However, both textured insole surfaces reduced postural sway for the older group especially in the eyes closed condition on a foam surface. These findings suggest that textured insole surfaces can reduce postural sway in older people, particularly during more challenging balance tasks. Textured insole surfaces may afford a low-cost means of decreasing postural sway, providing an important intervention in falls prevention.

Role of ankle mobility in foot rollover during gait in individuals with diabetic neuropathy

BACKGROUND

The purpose of this study was to investigate the ankle range of motion during neuropathic gait and its influence on plantar pressure distribution in two phases during stance: at heel-strike and at push-off.

METHODS

Thirty-one adults participated in this study (control group, n=16; diabetic neuropathic group, n=15). Dynamic ankle range of motion (electrogoniometer) and plantar pressures (PEDAR-X system) were acquired synchronously during walking. Plantar pressures were evaluated at rearfoot, midfoot and forefoot during the two phases of stance. General linear model repeated measures analysis of variance was applied to investigate relationships between groups, areas and stance phases.

FINDINGS

Diabetic neuropathy patients walked using a smaller ankle range of motion in stance phase and smaller ankle flexion at heel-strike (P=0.0005). Peak pressure and pressure-time integral values were higher in the diabetic group in the midfoot at push-off phase when compared to heel-strike phase. On the other hand, the control group showed similar values of peak pressure in midfoot during both stance phases.

INTERPRETATION

The ankle mobility reduction observed could be associated to altered plantar pressure distribution observed in neuropathic subjects. Results demonstrated that midfoot and forefoot play a different role in subjects with neuropathy by receiving higher loads at push-off phase that are probably due to smaller ankle flexion at stance phase. This may explain the higher loads in anterior areas of the foot observed in diabetic neuropathy subjects and confirm an inadequate foot rollover associated to the smaller ankle range of motion at the heel-strike phase.

[The tripod support of the foot. An analysis of pressure distribution under static and dynamic loading]

A "tripod" loading of the human foot, as it is mentioned in some textbooks, was not found in a pressure distribution study with 111 adults. For bipedal standing as well as walking peak pressures beneath the 3rd metatarsal head were substantially higher than under the metatarsal heads I and V. Correlation analyses demonstrated that the pressure distribution during standing reveals only little information about the dynamic loads under the foot during gait. Gender differences in the load bearing behavior of the foot as well as significant correlations of peak pressures towards body weight and foot contact area were found.

Musculoskeletal disorders associated with obesity: a biomechanical perspective

Despite the multifactorial nature of musculoskeletal disease, obesity consistently emerges as a key and potentially modifiable risk factor in the onset and progression of musculoskeletal conditions of the hip, knee, ankle, foot and shoulder. To date, the majority of research has focused on the impact of obesity on bone and joint disorders, such as the risk of fracture and osteoarthritis. However, emerging evidence indicates that obesity may also have a profound effect on soft-tissue structures, such as tendon, fascia and cartilage. Although the mechanism remains unclear, the functional and structural limitations imposed by the additional loading of the locomotor system in obesity have been almost universally accepted to produce aberrant mechanics during locomotor tasks, thereby unduly raising stress within connective-tissue structures and the potential for musculoskeletal injury. While such mechanical theories abound, there is surprisingly little scientific evidence directly linking musculoskeletal injury to altered biomechanics in the obese. For the most part, even the biomechanical effects of obesity on the locomotor system remain unknown. Given the global increase in obesity and the rapid rise in musculoskeletal disorders, there is a need to determine the physical consequences of continued repetitive loading of major structures of the locomotor system in the obese and to establish how obesity may interact with other factors to potentially increase the risk of musculoskeletal disease.

The impact of childhood obesity on musculoskeletal form

Despite the greater prevalence of musculoskeletal disorders in obese adults, the consequences of childhood obesity on the development and function of the musculoskeletal system have received comparatively little attention within the literature. Of the limited number of studies performed to date, the majority have focused on the impact of childhood obesity on skeletal structure and alignment, and to a lesser extent its influence on clinical tests of motor performance including muscular strength, balance and locomotion. Although collectively these studies imply that the functional and structural limitations imposed by obesity may result in aberrant lower limb mechanics and the potential for musculoskeletal injury, empirical verification is currently lacking. The delineation of the effects of childhood obesity on musculoskeletal structure in terms of mass, adiposity, anthropometry, metabolic effects and physical inactivity, or their combination, has not been established. More specifically, there is a lack of research regarding the effect of childhood obesity on the properties of connective tissue structures, such as tendons and ligaments. Given the global increase in childhood obesity, there is a need to ascertain the consequences of persistent obesity on musculoskeletal structure and function. A better understanding of the implications of childhood obesity on the development and function of the musculoskeletal system would assist in the provision of more meaningful support in the prevention, treatment and management of the musculoskeletal consequences of the condition.

The biomechanics of restricted movement in adult obesity

In spite of significant advances in the knowledge and understanding of the multi-factorial nature of obesity, many questions regarding the specific consequences of the disease remain unanswered. In particular, there is a relative dearth of information pertaining to the functional limitations imposed by overweight and obesity. The limited number of studies to date have mainly focused on the effect of obesity on the temporospatial characteristics of walking, plantar foot pressures, muscular strength and, to a lesser extent, postural balance. Collectively, these studies have implied that the functional limitations imposed by the additional loading of the locomotor system in obesity result in aberrant mechanics and the potential for musculoskeletal injury. Despite the greater prevalence of musculoskeletal disorders in the obese, there has been surprisingly little empirical investigation pertaining to the biomechanics of activities of daily living or into the mechanical and neuromuscular factors that may predispose the obese to injury. A better appreciation of the implications of increased levels of body adiposity on the movement capabilities of the obese would afford a greater opportunity to provide meaningful support in preventing, treating and managing the condition and its sequelae. Moreover, there is an urgent need to establish the physical consequences of continued repetitive loading of major structures of the body, particularly of the lower limbs in the obese, during the diverse range of activities of daily living.

The biomechanics of adiposity--structural and functional limitations of obesity and implications for movement

Obesity is a significant health problem and the incidence of the condition is increasing at an alarming rate worldwide. Despite significant advances in the knowledge and understanding of the multifactorial nature of the condition, many questions regarding the specific consequences of the disease remain unanswered. For example, there is a dearth of information pertaining to the structural and functional limitations imposed by overweight and obesity. A limited number of studies to date have considered plantar pressures under the feet of obese vs. non-obese, the influence of foot structure on performance, gait characteristics of obese children and adults, and relationships between obesity and osteoarthritis. A better appreciation of the implications of increased levels of body weight and/or body fat on movement capabilities of the obese would provide an enhanced opportunity to offer more meaningful support in the prevention, treatment and management of the condition.

Heel to toe motion characteristics in Parkinson patients during free walking

OBJECTIVE

Plantar pressures of Parkinson patients in a mild or moderate stage of the disease were analyzed in order to determine characteristics of the heel to toe motion of the foot in Parkinson patients during free walking.

DESIGN

Pressure sensitive insoles were used to quantify the in-shoe pressure distribution for 24 patients with Parkinson's disease and for 24 age-matched healthy adults. Peak plantar pressures, relative loads and the variability of relative loads were analyzed for 10 different anatomical foot areas. Inferential statistics and regression analyses were performed to compare subject groups and to relate pressure data to a clinical score (Webster).

BACKGROUND

It is well-known that Parkinson patients experience disorders of balance, posture and gait. Recent studies revealed that Parkinson patients show abnormalities in foot strike during walking. However, only little is known about the heel to toe motion of the foot in Parkinson patients in compensating for instability during walking.

RESULTS

Parkinson patients show significant changes in foot loading behavior. Parkinson patients have a reduced impact at heel strike. This mechanism was found to be related to the severity of the disease. Furthermore, Parkinson patients show a trend towards higher relative loads in the forefoot regions combined with a load shift towards medial foot areas. These mechanisms are highly stereotypical.

CONCLUSION

Parkinson patients, even in a mild or moderate stage of the disease, show significant changes in heel to toe motion of the foot during free walking. The characteristics of Parkinsonian gait are probably caused by adaptive mechanisms of the patients to avoid unsteadiness during walking.

RELEVANCE

The results of this study revealed that Parkinson patients have characteristic heel to toe motion pattern. The determination of the foot-loading pattern using plantar pressure measurement may be used as a valuable tool for diagnostic, treatment and rehabilitation purposes. Furthermore, the strategy of the forefoot control in gait of Parkinson patients should be considered in Parkinsonian research.

Plantar pressure differences between obese and non-obese adults: a biomechanical analysis

OBJECTIVE

To investigate plantar pressure differences between obese and non-obese adults during standing and walking protocols using a pressure distribution platform.

SUBJECTS

Thirty-five males (age 42.4+/-10.8 y; 67-179 kg) and 35 females (age 40.0+/-12.6 y; 46-150 kg) divided into obese (body mass index (BMI) 38.75+/-5.97 kg/m2) and non-obese (BMI 24.28+/-3.00 kg/m2) sub-groups, respectively.

MEASUREMENTS

Data collection was performed with a capacitive pressure distribution platform with a resolution of 2 sensors/cm2 (Emed F01, Novel GmbH, München). The measurement protocol included half and full body weight standing on the left, right and both feet, respectively, and walking across the platform, striking with the right foot. Pressures were evaluated for eight anatomical sites under the feet.

RESULTS

For both men and women, the mean pressure values of the obese were higher under all anatomical landmarks during half body weight standing. Significant increases in pressure were found under the heel, mid-foot and metatarsal heads II and IV for men and III and IV for women. Foot width during standing was also significantly increased in obese subjects. For walking, significantly higher peak pressures were also found in both obese males and females.

CONCLUSION

Compared to a non-obese group, obese subjects showed increased forefoot width and higher plantar pressures during standing and walking. The greatest effect of body weight on higher peak pressures in the obese was found under the longitudinal arch of the foot and under the metatarsal heads. The higher pressures for obese women compared to obese men during static weight bearing (standing) may be the result of reduced strength of the ligaments of the foot.

Pressure distribution measurements for evaluation of running shoe properties

The loading of individual foot structures which may play an important role in the occurrence of overuse injuries can be determined by using pressure distribution devices. In-shoe pressure measurements are of special interest as they provide information about the changes in foot to ground interactions with footwear modifications. Several studies have investigated the magnitudes of plantar in-shoe pressures at different running velocities. The first ray of the foot, composed of first metatarsus and hallux, was identified as one of the main load bearing structures during the push-off phase. Low correlations were found for the relationships of plantar pressures to ground reaction force or shock related variables. Pressure measurements provide a unique insight into the interaction between the human body, footwear and the ground. Substantial differences can be found in the peak pressure and relative load patterns due to different shoe constructions. It was also shown that plantar pressure measurement can be employed to identify changes of footwear properties with use. Although in-shoe pressure data offer detailed information about the loading behavior of the foot in various activities, at present conclusions for medical implications are still speculative.

Measurements of rearfoot motion during running

Excessive rearfoot motion is an important factor that has been linked to the development of injuries in running. Therefore, extensive research has been performed that to investigate the movement of the foot and factors that influence the degree of rearfoot motion. Several methodological procedures are available that indirectly determine the degree of rearfoot movement. High-speed film, high-speed video and opto-electric techniques have been used to analyse the posterior aspect of the heel counter of the shoe in the frontal plane to determine rearfoot motion at ground contact on a treadmill or during overground running. Recent studies used invasive pin methods to determine rearfoot motion during running under different conditions. Using a non-invasive approach, electrogoniometers have been used to quantify rearfoot motion. The purpose of this study was to explore the use of an in-shoe electrogoniometric method to investigate rearfoot motion during running in different running shoes. The results showed that rearfoot motion variables were lower using the in-shoe goniometer compared to a heel counter method. This confirms previous bone pin studies where significant lower eversion and eversion velocity values were revealed by the bone pins compared to the shoe counter markers. Thus, external measurements seem to overestimate rearfoot motion significantly. On the other hand, the in-shoe measurements revealed slightly lower GRF related values. As with any other shoe insert, an in-shoe device elevates the foot slightly and thus may influence the mechanical behaviour of the shoe.

The influence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists

The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev x min(-1)) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.

Significant difference in p53 and p21 protein immunoreactivity in HPV 16 positive and HPV negative breast carcinomas

Human papillomavirus (HPV) 16 has previously been found in 19/41 breast carcinomas (46%) in women with a history of HPV 16 positive CIN III lesions. There was no significant difference in distribution of histological subtypes, mean or median tumour diameter or number of regional lymph node metastases in the HPV positive and HPV negative breast carcinoma groups. P53, p21 and c-erbB-2 proteins were analysed by immunohistochemistry in the HPV 16 positive and HPV negative breast carcinomas. There was a significant difference in p53 and p21 protein immunoreactivity between HPV 16 positive and HPV negative breast carcinomas (p = 0.0091 and p = 0.0040), with a significant less detectable p53 and p21 protein immunoreactivity in the HPV 16 positive cases. There was also a significant difference in the coexpression of p53/p21 between the HPV 16 positive and HPV 16 negative breast carcinomas (p = 0.002). No significant difference in immunostaining for c-erbB-2 protein in the two groups was found (p = 0.15), or for the coexpression of p53/c-erbB-2 (p = 0.19). The significantly lower expression of p53 and p21 proteins in HPV 16 positive than in HPV 16 negative breast carcinomas supports the hypothesis of inactivation and degradation of wild-type p53 proteins by HPV 16 E6 and that p53 mutation is not necessary for transformation in the HPV 16 positive cases.

HPV 16 in multiple neoplastic lesions in women with CIN III

Paraffin embedded material of multiple primary cancers and other hyperplastic tumours from fifteen patients were analyzed by PCR and in situ hybridization for the presence of HPV DNA in the lesions. All patients had also high grade cervical intraepithelial dysplasia (CIN III) and breast carcinomas and were selected from a previous study enrolling 46 women with CIN III and breast carcinomas. HPV 16 was detected by PCR in 8/15 patients (53%), with eleven HPV 16 positive tumours. HPV 16 was detected in two malignant melanomas, one basal cell carcinoma, one squamous cell carcinoma of the vulva, one Bowen disease of the vulva, two high grade vaginal intraepithelial neoplasias, one cancer corporis uteri, one bronchial carcinoma and two lymphomas. Three cases, two high grade vaginal intraepithelial neoplasia and a squamous cell carcinoma of the vulva, were also reported to be positive by in situ hybridization. 5/8 patients (63%) with HPV 16 positive second cancers had also HPV 16 positive breast carcinomas. All fifteen patients with second cancers after CIN III had HPV 16 positive CIN III lesions; 53% of the patients had also a familial cancer history. We assume that HPV 16 may be involved in the development of different second cancers in women with HPV 16 positive CIN III.

HPV positive bronchopulmonary carcinomas in women with previous high-grade cervical intraepithelial neoplasia (CIN III)

A significant higher incidence of some cancers, especially lung cancer, has been found in women with previous HPV-related (human papillomavirus) urogenital and anal neoplasias than in individuals without this particular clinical history. The aim of our study was to investigate whether HPV is present in both CIN III (cervical intraepithelial neoplasia) lesions and bronchopulmonary second primary cancers in women with a clinical history of both diseases. Paraffin-embedded tumour tissue from 75 patients with bronchopulmonary carcinomas was examined using the polymerase chain reaction (PCR) technique and in situ hybridization for the presence of human HPV. In total, 51 primary tumours without metastases, 11 primary tumours with metastases and 13 lymph node metastases without available tissue from primary tumours were analysed. In our study 37/75 primary bronchopulmonary tumours (49%) were identified as HPV positive by the PCR method: 18 cases were purely HPV 16 positive (49%), 12 were purely HPV 6 positive (32%), 5 cases were HPV 16/6 positive (14%), 1 case was HPV 16/11 positive (2%) and 1 case was HPV 16/18 positive (2%). Fourteen metastases were HPV positive, and HPV 16, 11 and 6 were detected in both regional and distant metastases. Two of the HPV 16-positive metastases were brain metastases from two separate HPV 16-positive primary tumours; 35% of the HPV-positive cases were adenocarcinomas, 30% squamous cell carcinomas, 22% oat cell carcinomas, 5% large cell carcinomas, 3% anaplastic carcinoma, 3% low-differentiated carcinoma, and 3% malignant cylindroma. The CIN III lesions from 34 of the 37 HPV-positive bronchopulmonary carcinomas were analysed by PCR. The overall HPV positivity in the CIN III lesions was 74% (25/34 cases): 48% were purely HPV 16 positive, 24% purely HPV 6 positive, 24% HPV 16/6 positive and 4% were HPV 18 positive. Our results indicate that HPV is also involved in the development of bronchopulmonary cancers in women with a history of CIN III lesions.

Multiple primary cancers and HPV infection: are they related?

Multiple primary cancers have been reported with increasing frequency in recent years, but the presence of foreign DNA sequences of infectious agents in tumours arising in the same patient has so far not been investigated. We report a case of a patient with Hodgkin's lymphoma, an "in situ" cervix carcinoma and an adenocarcinoma of the right and left mammary gland. In all the tumour samples we detected the presence of DNA genomic sequences of Papillomavirus type 16. Our results suggest that HPV infection may be an exogenous risk factor even in second primary tumours of non-epithelial origin.

Human papillomavirus 16 in breast cancer of women treated for high grade cervical intraepithelial neoplasia (CIN III)

Women with both a history of high grade cervical intraepithelial neoplasia (CIN III) and breast carcinoma as second primary cancer were selected for studying the presence of HPV in breast carcinomas. Paraffin embedded material from 38 patients with 41 breast carcinoma cases after CIN III were examined by polymerase chain reaction (PCR) and in situ hybridization. By PCR we detected HPV 16 DNA in 19 out of 41 cases (46%) of the breast carcinomas. One case proved to be HPV 16 positive also by in situ hybridization. HPV 16 was also detected in 32 out of the 38 patients with CIN III (84%). All HPV 16 positive breast carcinomas were HPV 16 positive in their corresponding CIN III lesions. Eight patients with diagnosed breast cancer before the CIN III lesions were used as controls. None of these had HPV positive breast carcinomas. No cases were positive for HPV 11, 18, or 33. HPV 16 was detected in the primary tumours, in local metastases from HPV 16 positive tumours, in a distant HPV 16 positive breast carcinoma metastasis to the colon, and in other primary cancers in patients with HPV 16 positive breast carcinomas and HPV 16 positive CIN III. Estrogen and progesterone receptors were quantified in the HPV positive and HPV negative breast carcinomas, and there was no significant difference in the fraction positive in the two groups. Oncogenic HPV DNA might be transported from an original site of infection to other organs by blood or lymph, and possibly be a factor in the development of cancer in different organs.

A novel grid polymerase chain reaction (G-PCR) approach at ultrastructural level to detect target DNA in cell cultures and tissues

A novel grid polymerase chain reaction (G-PCR) method has been developed to be used at the ultrastructural level and with a high degree of resolution. Samples applied to test the method were fresh cell lines (CaSki, SiHa) and HPV-16 DNA-containing tissues rescued from routine paraffin blocks. The specimens were embedded in Epon-Araldite and/or hydrophilic-resin LRWhite. Ultrathin sections mounted on grids were subjected to G-PCR using an HPV-16-specific primer set. The amplified products were identified by auro-immunohistochemical labelling of the biotinylated nucleotide. The results indicated successful amplification of target DNA in both cell and tissue samples, being confined to the intranuclear region. The negative controls [HeLa cells, isolated mammary carcinoma cell cultures (MCF 7, and T47-D) (ATCC) (U.S.A.), normal thyroid tissue and steroid-producing tumour tissue] failed to exhibit any amplification of the target DNA sequences. The sensitivity of the G-PCR system was evaluated by performing a parallel in situ hybridization (ISH) of serial sections. The signals obtained from G-PCR were more intense than those of ISH and more informative as to the precise subcellular localization of amplicons.

Restriction of foot supination by ankle braces in sudden fall situations

OBJECTIVE: To investigate the restriction of foot supination in different shoe orthotic combinations for unexpected ankle turns. DESIGN: A supination platform was used to experimentally induce sudden ankle turns. BACKGROUND: This study expanded on previous investigations of the effectiveness of different ankle braces and the influence of shoe material on foot supination. METHODS: For 21 male subjects pressure distribution data, achilles tendon angle, and supination velocity were collected. A comparison between a shoe with cut upper material and an intact shoe was done to show the influence of upper material on supination. The effectiveness of four different orthotics inside of an intact shoe were tested in comparison to the same shoe without ankle brace. Additionally, subjects rated their perceived supination movement of the foot. RESULTS: Between experimental conditions no large differences for the pressure distribution patterns were found. Three of the ankle braces reduced foot supination as well as supination velocities. More than two times lower supination values were measured for a footwear condition in which the upper material was cut away. Already during the free-fall most ankle braces caused a substantial reduction of foot inversion. CONCLUSION: The experiments demonstrated the influence of the upper material of a shoe and different orthotics on foot supination. Biomechanical measurements are necessary because of limited capabilities of subjects in detecting subtalar angular motions. RELEVANCE: This study investigated the effectiveness of different shoe conditions and ankle braces under experimental conditions that simulated unexpected ankle turns, the most frequent causes of sport injuries. The results of the study provide insights into which factors influence the amount of foot supination during unexpected ankle turns.

Dynamic plantar pressure distribution measurements in hemiparetic patients

OBJECTIVE: A comparison of plantar pressure distribution of hemiparetic patients with a control group was performed to determine quantitative, objective and reproducible criteria for better assessment of hemiparetic gait. DESIGN: This empirical, descriptive study used a clinical sample of 18 hemiparetic patients and compared the data to previously published data from 111 healthy persons. BACKGROUND: Several biomechanical methods have been used in the past to evaluate and classify hemiplegic gait, for example kinetic, cinematographic, or electromyographic systems, but plantar pressure distribution measurement has not been studied. METHODS: Peak pressures were determined under the feet of 18 hemiparetic patients during stance phase using a capacitive pressure distribution platform (EMED-F01 system, Novel GmbH). RESULTS: Hemiparetic patients showed considerably lower peak pressures under all anatomical structures and an unexpected medial load shift in the forefoot. CONCLUSIONS: The grade of spasticity seems to be the most important cause for expression of the medial load shift. Individual pressure distribution gait analysis, as shown in an example, may improve assessment and therapy of hemiparetic patients. RELEVANCE: Plantar pressure distribution data from hemiparetic patients can be used for an analysis of lower extremity dysfunctions. This method may also be employed to assess objectively the success of drug treatment and/or other rehabilitation processes. In particular, individual plantar pressure data from patients will provide additional clinical information for rehabilitation physicians, therapists, and engineers.

Differential shock transmission response of the human body to impact severity and lower limb posture

The shocks imparted to the foot during locomotion may lead to joint-degenerative diseases and jeopardize the visual-vestibular functions. The body relies upon several mechanisms and structures that have unique viscoelastic properties for shock attenuation. The purpose of the present study was to determine whether impact severity and initial knee angle (IKA) could alter the shock transmission characteristics of the body. Impacts were administered to the right foot of 38 subjects with a human pendulum device. Combinations of velocities (0.9, 1.05 and 1.2 m s-1) and surfaces (soft and hard foams) served to manipulate impact severity in the first experiment. Three IKA (0, 20 and 40 degrees) were examined in the second experiment. Transmission between shank and head was characterized by measuring the shock at these sites with miniature accelerometers. Velocity and surface had no effect on the frequency profile of shock transmission suggesting a consistent response of the body to impact severity. Shank shock power spectrum features accounted for the lower shock ratio (head/shank) measured under the hard surface condition. IKA flexion caused considerable reduction in effective axial stiffness of the body (EASB), 28.7-7.9 kNm-1, which improved shock attenuation. The high correlation (r = 0.97) between EASB and shock ratio underscored the importance of EASB to shock attenuation. The present findings provide valuable information for the development of strategies aimed at protecting the joints, articular cartilage, spine and head against locomotor shock.

Dominant role of interface over knee angle for cushioning impact loading and regulating initial leg stiffness

For in vivo impact loadings administered under controlled initial conditions, it was hypothesized that larger initial knee angles (IKA) and softer impacting interfaces would reduce impact loading and initial leg stiffness. A human pendulum was used to deliver controlled impacts to the right foot of 21 subjects for three IKA (0, 20 and 40 degrees) and three interfaces (barefoot, soft and hard EVA foams). The external impact force and the shock experienced by the subjects' shank were measured simultaneously with a wall mounted force platform and a skin mounted accelerometer, respectively. Stiffness of the leg was derived using impact velocity and wall reaction force data. The results disproved the role of the knee joint in regulating initial leg stiffness and provided only partial support for the hypothesized improved cushioning. Larger knee flexion at contact reduced impact force but increased the shock travelling throughout the shank. Conversely, softer interfaces produced sizable reductions in both initial leg stiffness and severity of the impact experienced by the lower limb. Force rate of loading was found to be highly correlated (r = 0.95) to limb stiffness that was defined by the heel fat pad and interface deformations. These results would suggest that interface interventions are more likely to protect the locomotor system against impact loading than knee angle strategies.

The influence of stretching and warm-up exercises on Achilles tendon reflex activity

The aim of this study was to investigate the acute effects of prior exercise (warm-up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10-min warm-up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom-built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between-subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (-5%; P < 0.05), the force rise rate (-8%; P < 0.01), the half relaxation rate (-5%; N.S.), the EMG amplitudes (G, -16%; S, -17%; P < 0.01) and integrals (G, -15%; S, -18%; P < 0.01), and an increase in EMG latencies (G, +3%; S, +1%; P < 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (-2%; N.S.), the force rise rate and half relaxation rate increased by 8 and 12%, respectively (P < 0.01), and the impulse (force-time integral; -12%), EMG amplitudes (G, -20%; S, -23%; P < 0.01), integrals (G, -18%; S, -23%; P < 0.01) and latencies (G, -1%; S, -2%; P < 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm-up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance-enhancing effect.

Second primary cancers in patients with carcinoma in situ of the uterine cervix. The Norwegian experience 1970-1992

Multiple primary cancers in the same individual occur rarely. Consequently, a large number of cancer patients have to be followed for long periods to obtain adequate information about their risk of subsequent tumour development. Studies of multiple malignancies are of interest, since they may provide information on common or opposite risk factors. In the present study, the risk of second primary cancers following carcinoma in situ of the uterine cervix diagnosed in Norway in the period 1970-1992 was examined and quantified. Altogether, 37,001 patients with carcinoma in situ were followed from the date of diagnosis until 31 December 1992. The follow-up period was divided into 5-year intervals. The results were expressed as standardized incidence ratios (SIR = O/E), and their 95% confidence intervals were given. A total of 1,037 second primary cancers in 989 individuals were identified. There was no overall excess of second primary cancers. However, there were differences depending on the site: cancers of the oesophagus, nose, nasal cavities, trachea, bronchus, lung, vulva, vagina, bladder and other urinary organs, and other skin cancers, excluding basal-cell carcinoma, occurred more frequently. A lower risk than expected was noted for cancer of the cervix uteri and cancer of the corpus uteri. There was a rising trend with time in the observed/expected ratio for cancer of urinary organs. In the group of patients evaluated, the likelihood of subsequent tumour development was no greater than in the general female population. Nevertheless, cancer sites of higher and of lower risk than expected were identified among the carcinoma-in situ patients.

[C-reactive protein and biological defense]

This article reviews recent findings suggesting a specific tumouricidal effect of C-reactive protein (CRP). A peptidic fragment of CRP, called RS 83277, has shown a significant anti-tumour effect in laboratory animals. The mechanism is not fully understood, but is possibly mediated via the macrophages. Both macrophages and monocytes show increased tumoricidal activity after stimulation with RS 83277. The article also reviews the regulation of CRP synthesis and secretion, as well as the structure, binding capacities, and important biological properties of CRP.

The role of external nonrigid ankle bracing in limiting ankle inversion

The purpose of this study was to measure the effectiveness of the nonrigid subtalar stabilizer (STS) ankle brace under conditions similar to an unexpected fall that could lead to a lateral ligament injury. The calcaneal inversion angles, times, and ground reaction forces were measured when the subject's right foot, bearing body weight, was suddenly inverted to a side slope of 22 degrees. Thirty subjects, 15 women and 15 men, participated in the study. The overall inversion drop was divided into two phases, free fall and loading. Based on the data of this study it is suggested that the major function of a brace is to restrict the amount of foot inversion during the fall before actual landing occurs rather than functioning as a force bypass for the lateral ligaments during loading after foot contact. The results showed that the brace significantly (p < 0.05) reduced the maximum calcaneal inversion angle from 27.4 +/- 6.1 to 18.3 +/- 6.0 degrees for the overall drop, significantly lengthened the inversion time from 0.14 +/- 0.04 to 0.18 +/- 0.04 s for the overall drop, and significantly reduced the calcaneal peak inversion velocity from 324.6 +/- 111.9 to 165.2 +/- 66.5 degrees/s during loading, and from 278.7 +/- 120.0 to 183.0 +/- 108.7 degrees/s for the overall drop. Following exercise, which incorporated lateral movements and sprinting, the STS ankle brace continued to provide significant (p < 0.05) reduction in the calcaneal inversion angle and velocity, although some of its effectiveness was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Plantar pressure distribution patterns of young school children in comparison to adults

Peak pressures and relative loads were determined under the feet of 125 children between 6 and 10 years of age. These results were compared with previously published data from 111 adults. A capacitive pressure distribution platform with a resolution of 2 sensors/cm2 was used for data collection during walking. As compared with the group of adults, the school children showed considerably lower peak pressures under all anatomical structures. Larger foot dimensions with respect to body weight result in reduced foot pressures for the children by distributing the ground reaction forces across larger contact areas. With increasing age, a medial load shift in the forefoot could be observed for the older children. Data analysis of the pressures under the midfoot revealed that the longitudinal foot arch development is almost complete before the age of 6. Contrary to the findings in adults, body weight was identified to be of major influence on the magnitude of the pressures under the feet of school children. No differences were found for the foot pressures between boys and girls.

Transfer of tennis racket vibrations onto the human forearm

One of several factors suspected in the development of lateral epicondylitis, often referred to as tennis elbow, is the impact-induced vibration of the racket-and-arm system at ball contact. Using two miniature accelerometers at the wrist and the elbow of 24 tennis players, the effects of 23 different tennis racket constructions were evaluated in a simulated backhand stroke situation. The influences of body weight, skill level, and tennis racket construction onto the magnitude of vibrations at wrist and elbow were investigated. Amplitudes, integrals, and fourier components were used to characterize arm vibration. More than fourfold reductions in acceleration amplitude and integral were found between wrist and elbow. Off-center as compared with center ball impacts resulted in approximately three times increased acceleration values. Between subjects, body weight as well as skill level were found to influence arm vibration. Compared with proficient players, a group of less skilled subjects demonstrated increased vibration loads on the arm. Between different racket constructions, almost threefold differences in acceleration values could be observed. Increased racket head size as well as a higher resonance frequency of the racket were found to reduce arm vibration. The vibration at the arm after ball impact showed a strong inverse relationship (r = -0.88) with the resonance frequency of tennis rackets.

Cushioning properties of footwear during walking: accelerometer and force platform measurements

Repetitive impact loadings of the musculoskeletal system have been linked to the development of osteoarthritis and low back pain. An important function of footwear is to attenuate foot-ground impacts. The purpose of this study was to measure the effects of footwear types upon the impact ground reaction forces and the transient stress waves transmitted up the lower limb. The results have shown that both transient stress waves and ground reaction forces are affected by footwear during walking. Furthermore, with harder midsoles footwear, higher shock was transmitted to the lower extremities. This paper confirms the importance of using footwear to cushion the impact generated at heelstrike during walking. It also reveals that both shock and force measurements are required to evaluate and prescribe footwear to patients suffering from impact-related chronic diseases.

Pressure distribution patterns under the feet of children in comparison with adults

Peak pressures and regional impulses were determined under the feet of 15 children and 111 adults by means of a capacitive pressure distribution platform. The measurements were taken during walking and running and revealed insights into foot function during the process of locomotion skill acquisition. Considerably reduced peak pressures in the infant group could be attributed to a softer foot structure and a lower body-weight to foot-contact area ratio. An almost three times higher relative load under the midfoot of the infant foot shows that the longitudinal foot arch is still a weak structure. Within a few months of gait development remarkable changes toward an adult loading pressure pattern were observed.

Contribution of angular motion and gravity to tibial acceleration

A bone-mounted accelerometer and high-speed cinematography were used to compare the axial tibial acceleration caused by ground impact with the total tibial axial acceleration as measured by a transducer. Due to the effects of gravity and tibial angular motion, the magnitude of the peak acceleration at foot strike was 43% below and 18% above the peak axial acceleration due to impact for running and walking, respectively. Depending on the distance of the accelerometer from the tibial center of rotation which is located at the ankle joint, different axial acceleration signals should be expected during comparable locomotor activities.