Hylton B. Menz

Reliability of the GAITRite® walkway system for the quantification of temporo-spatial parameters of gait in young and older people

The purpose of this study was to evaluate the test-retest reliability of an instrumented walkway system (the GAITRite mat) for the measurement of temporal and spatial parameters of gait in young and older people. Thirty young subjects (12 males, 18 females) aged between 22 and 40 years (mean 28.5, S.D. 4.8) and 31 older subjects (13 males, 18 females) aged between 76 and 87 years (mean 80.8, S.D. 3.1) walked at a self-selected comfortable walking speed across the pressure-sensor mat three times and repeated the process approximately 2 weeks later. Intra-class correlation coefficients (ICC), coefficients of variation (CV) and 95% limits of agreement were then determined. For both groups of subjects, the reliability of walking speed, cadence and step length was excellent (ICCs between 0.82 and 0.92 and CVs between 1.4 and 3.5%). Base of support and toe in/out angles, although exhibiting high ICCs, were associated with higher CVs (8.3-17.7% in young subjects and 14.3-33.0% in older subjects). It is concluded that the GAITRite mat exhibits excellent reliability for most temporo-spatial gait parameters in both young and older subjects, however, base of support and toe in/out angles need to viewed with some caution, particularly in older people.

Accelerometry: A technique for quantifying movement patterns during walking

The popularity of using accelerometer-based systems to quantify human movement patterns has increased in recent years for clinicians and researchers alike. The benefits of using accelerometers compared to more traditional gait analysis instruments include low cost; testing is not restricted to a laboratory environment; accelerometers are small, therefore walking is relatively unrestricted; and direct measurement of 3D accelerations eliminate errors associated with differentiating displacement and velocity data. However, accelerometry is not without its disadvantages, an issue which is scarcely reported in gait analysis literature. This paper reviews the use of accelerometer technology to investigate gait-related movement patterns, and addresses issues of acceleration measurement important for experimental design. An overview of accelerometer mechanics is provided before illustrating specific experimental conditions necessary to ensure the accuracy of gait-related acceleration measurement. A literature review is presented on how accelerometry has been used to examine basic temporospatial gait parameters, shock attenuation, and segmental accelerations of the body during walking. The output of accelerometers attached to the upper body has provided useful insights into the motor control of normal walking, age-related differences in dynamic postural control, and gait patterns in people with movement disorders.

Acceleration patterns of the head and pelvis when walking on level and irregular surfaces.

The aim of this study was to evaluate acceleration patterns at the head and pelvis while subjects walked on a level and an irregular walking surface, to develop an understanding of how the postural control system responds to challenging walking conditions. Thirty young, healthy subjects walked on a level corridor and on artificial grass underlain with foam and wooden blocks placed in an arbitrary manner. Temporo-spatial gait parameters and acceleration patterns at the head and pelvis were measured. The results revealed that when walking on the irregular surface, subjects were able to maintain their velocity, but adopted a slower and more variable cadence and a significantly longer stride length. The magnitude of pelvis accelerations increased, however head accelerations were not affected by the walking surface. When considered as an overall pattern of movement, these findings suggest that one of the primary objectives of the postural control system when walking on irregular surfaces is head control, and that subjects adapt their stepping pattern on irregular surfaces to ensure that the head remains stable.

Visual contributions to postural stability in older adults.

Background: With advancing age, there is a generalized reduction in visual functioning which has been associated with impaired postural stability and increased risk of falls. However, little is known about which visual abilities are the most important in the control of postural sway when standing. Objective: To determine whether specific visual abilities predict stability when standing on firm and compliant surfaces. Methods: Tests of visual function, peripheral sensation, strength, reaction time and sway were administered to 156 community-dwelling men and women aged 63–90 years. The visual tests included high- and low-contrast visual acuity, contrast sensitivity, depth perception, stereopsis and lower visual field size. Postural sway was measured with eyes open on a firm and a compliant foam rubber surface. Results: On the firm surface, sway was significantly associated with only one sensorimotor measure: proprioception in the lower limbs. In contrast, on the compliant surface, sway was associated with all of the visual measures, quadriceps strength and reaction time. Multiple regression analysis revealed that contrast sensitivity, stereopsis and quadriceps strength were significant independent predictors of total sway when subjects stood on the compliant surface. Conclusion: The study findings confirm the importance of vision, in particular contrast sensitivity and stereopsis, in the control of posture under challenging conditions, and suggest some mechanisms for the association between impaired vision and falls in older people.

Footwear characteristics and foot problems in older people.

Background:Foot problems are common in older people, however the contribution of incorrectly fitting footwear and heel elevation to the development of foot pain and deformity has not been fully evaluated. Objectives: To examine the relationship between footwear characteristics and the prevalence of common forefoot problems in older people. Methods:Presence of foot pain and deformity were identified in 176 people (56 men and 120 women) aged 62–96 years (mean 80.09, SD 6.42) using a questionnaire and clinical assessment. Shoe fit was determined by comparing length, width and area measurements of shoes with foot measurements. Past and present use of high heels in women was documented, and heel elevation of footwear was measured. Results: Most subjects wore shoes narrower than their feet. Women wore shoes that were shorter, narrower and had a reduced total area compared to their feet than men. Wearing shoes substantially narrower than the foot was associated with corns on the toes, hallux valgus deformity and foot pain, whereas wearing shoes shorter than the foot was associated with lesser toe deformity. Wearing shoes with heel elevation greater than 25 mm was associated with hallux valgus and plantar calluses in women. Conclusion: Incorrectly fitting footwear is common in older people and is strongly associated with forefoot pathology and foot pain. These findings highlight the need for footwear assessment in the management of foot problems in older people.

Two feet, or one person? Problems associated with statistical analysis of paired data in foot and ankle medicine

In many fields of biomedical research, information is collected on multiple joints or organs from the same subject. For example, many ophthalmology studies record data from both eyes [1], rheumatology studies often assess both knees [2], and in the case of foot and ankle research, data are often collected from both feet. This raises a significant, yet frequently ignored problem pertaining to statistical analysis. One of the fundamental requirements of statistics is that each data point must represent an independent observation to justify being considered a “unit” [3]. In most cases, the unit of analysis is the subject, so if, for example, 50 subjects are enrolled in the study, each observation recorded from each subject counts as a single unit, i.e. n = 50. However, if data are recorded from both feet, a major problem arises. What is the unit of measurement—a subject, or a foot? Do we have a sample of n = 50 people, or a sample of n = 100 feet? A cursory examination of the foot and ankle literature reveals dozens of examples of statements like “We recruited thirty subjects (sixty feet)”, and in some cases, data are pooled from multiple toes [4] or multiple toenails [5] from the same subject. This issue is not merely pedantic—it has the potential to significantly influence the findings and interpretation of many investigations. Indeed, in a review of 196 randomised controlled trials of anti-inflammatory medications, 63% of studies were found to have used the wrong units of analysis [6]. The aim of this paper is to focus attention on the issue to hopefully stimulate further debate and to facilitate the development of a consensus as to how to address it.

The Contribution of Foot Problems to Mobility Impairment and Falls in Community-Dwelling Older People

OBJECTIVES: To investigate the relationship between foot problems, balance, and functional ability in community‐dwelling older people and to determine whether older people with a history of multiple falls exhibit greater foot impairment than those who have not fallen or who have fallen once only.

Prevalence and correlates of foot pain in a population-based study: the North West Adelaide health study

BackgroundFew population-based studies have examined the prevalence of foot pain in the general community. The aims of this study were therefore to determine the prevalence, correlates and impact of foot pain in a population-based sample of people aged 18 years and over living in the northwest region of Adelaide, South Australia.MethodsThe North West Adelaide Health Study is a representative longitudinal cohort study of n = 4,060 people randomly selected and recruited by telephone interview. The second stage of data collection on this cohort was undertaken between mid 2004 and early 2006. In this phase, information regarding the prevalence of musculoskeletal conditions was included. Overall, n = 3,206 participants returned to the clinic during the second visit, and as part of the assessment were asked to report whether they had pain, aching or stiffness on most days in either of their feet. Data were also collected on body mass index (BMI); major medical conditions; other joint symptoms and health-related quality of life (the Medical Outcomes Study Short Form 36 [SF-36]).ResultsOverall, 17.4% (95% confidence interval 16.2 – 18.8) of participants indicated that they had foot pain, aching or stiffness in either of their feet. Females, those aged 50 years and over, classified as obese and who reported knee, hip and back pain were all significantly more likely to report foot pain. Respondents with foot pain scored lower on all domains of the SF-36 after adjustment for age, sex and BMI.ConclusionFoot pain affects nearly one in five of people in the community, is associated with increased age, female sex, obesity and pain in other body regions, and has a significant detrimental impact on health-related quality of life.

Obesity and pronated foot type may increase the risk of chronic plantar heel pain : a matched case-control study

BackgroundChronic plantar heel pain (CPHP) is one of the most common musculoskeletal disorders of the foot, yet its aetiology is poorly understood. The purpose of this study was to examine the association between CPHP and a number of commonly hypothesised causative factors.MethodsEighty participants with CPHP (33 males, 47 females, mean age 52.3 years, S.D. 11.7) were matched by age (± 2 years) and sex to 80 control participants (33 males, 47 females, mean age 51.9 years, S.D. 11.8). The two groups were then compared on body mass index (BMI), foot posture as measured by the Foot Posture Index (FPI), ankle dorsiflexion range of motion (ROM) as measured by the Dorsiflexion Lunge Test, occupational lower limb stress using the Occupational Rating Scale and calf endurance using the Standing Heel Rise Test.ResultsUnivariate analysis demonstrated that the CPHP group had significantly greater BMI (29.8 ± 5.4 kg/m2 vs. 27.5 ± 4.9 kg/m2; P < 0.01), a more pronated foot posture (FPI score 2.4 ± 3.3 vs. 1.1 ± 2.3; P < 0.01) and greater ankle dorsiflexion ROM (45.1 ± 7.1° vs. 40.5 ± 6.6°; P < 0.01) than the control group. No difference was identified between the groups for calf endurance or time spent sitting, standing, walking on uneven ground, squatting, climbing or lifting. Multivariate logistic regression revealed that those with CPHP were more likely to be obese (BMI ≥ 30 kg/m2) (OR 2.9, 95% CI 1.4 – 6.1, P < 0.01) and to have a pronated foot posture (FPI ≥ 4) (OR 3.7, 95% CI 1.6 – 8.7, P < 0.01).ConclusionObesity and pronated foot posture are associated with CPHP and may be risk factors for the development of the condition. Decreased ankle dorsiflexion, calf endurance and occupational lower limb stress may not play a role in CPHP.

Foot Pain Impairs Balance and Functional Ability in Community-Dwelling Older People

Foot problem assessments were performed on 135 community-dwelling older people in conjunction with clinical tests of balance and functional ability. Eighty-seven percent of the sample had at least one foot problem, and women had a higher prevalence than men of foot pain, hallux valgus, plantar hyperkeratosis, lesser digital deformity, and digital lesions. Postural sway did not differ between older people with and without each of these foot conditions. However, the presence of specific foot conditions impaired performance in a more challenging balance test and in some functional tests. In particular, older people with foot pain performed worse in a leaning balance test, stair ascent and descent, an alternate step-up test, and a timed six-meter walk. Furthermore, multiple regression analyses revealed that foot pain was a significant independent predictor of performance in each of these tests. These results show that the presence of foot problems, particularly foot pain, impairs balance and functional ability. As foot pain is amenable to treatment, podiatric intervention has the potential to improve mobility and independence in older people.