Gait patterns in subjects with rheumatoid arthritis cannot be explained by reduced speed alone
Introduction
Gait is a complex human movement involving sensory input, central processing and neuromuscular responses. An effective motor response requires an intact neuromuscular system and sufficient muscle strength and range of motion to move and to maintain upright balance while moving. Walking enables us to move safely and efficiently from one place to another and take part in every day life. Therefore, gait can be considered as a major determinant of independent motor function.
Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory, systemic disease of unknown etiology. The initial changes of inflammation occur in the synovial membrane. Tendons, ligaments, cartilage, and the joint capsule are all subject to inflammation and destruction, leading to symptoms of pain, stiffness, swollen joints and fatigue. The disease activity is often changing, but in most cases disability and reduced activities of daily living are the outcome of RA [1].
In subjects with RA, gait and balance may be affected by foot deformities [2] and pain [3]. Reduced muscle strength [4], limited range of motion [5], disease activity [6] and fear of falling [7] may also contribute to changes in gait patterns compared to healthy subjects. Even at the early stages of RA these factors may lead to some degree of immobility and reduced participation in physical activities and, consequently, to inadequate performance in daily activities [4]. Thus, assessing spatiotemporal gait patterns can be useful in detecting decline or recovery of motor function.
Gait may be assessed in gait laboratories using sophisticated and costly procedures [8] or in the clinic using simple techniques such as visual observation [9] or a timing device [10]. Visual observation has been reported not to satisfy scientific criteria of reliability and validity [11]. A timing device can only measure walking speed or temporal variables. Lately, however, electronic contact-sensitive walkways have been introduced, which measure both spatial and temporal gait variables [12] and can be used in a laboratory as well as in a clinical setting.
Walking speed and spatiotemporal patterns may be useful indicators of pathology in the musculoskeletal system [10], [13]. Reduced speed is a typical feature observed among individuals with joint diseases. It has also been reported that spatiotemporal variables such as step length, cadence, stance phase, and step width may change with speed [14], [15]. However, to distinguish differences in spatiotemporal variables due to gait abnormalities from differences due to change in walking speed, gait data should be controlled for the effect of speed [13], [24]. Only then differences in gait strategy beyond those associated with speed can be disclosed. To our knowledge, the relationship between speed-dependent gait variables after controlling for the effect of speed in subjects with RA has not been investigated.
The purpose of this study was to assess characteristics of gait in subjects with RA by comparing gait parameters obtained in a clinical setting from subjects with RA and healthy ones, while controlling for the effect of differing gait speed. The following hypotheses were made:
- 1.
Subjects with RA walk slower than healthy individuals at self-selected speeds.
- 2.
Subjects with RA walk with shorter step length, increased cadence, increased stance time, and increased step width compared to healthy persons when controlling for the effect of gait speed.
Section snippets
Subjects
Twenty subjects with RA and 20 controls were recruited from a regional hospital in southern Norway. The RA group was recruited from the department of rheumatology from lists of subjects treated by Disease-Modifying Anti-rheumatic Drugs (DMARDs). The controls were recruited from the medical and mercantile staff. The study was approved by The Regional Committee for Medical Research Ethics. Informed consent was obtained from all participants.
Subjects with RA were included if they fulfilled the
Characteristics of the RA and control group
The groups were homogenous with respect to age and gender. Only education and physical activity differed significantly between the groups. The controls had longer education and were more physically active than the RA group. Descriptive characteristics of all subjects are presented in Table 1 and disease-specific characteristics of the RA group in Table 2.
Eleven subjects with RA used analgesics on the day of testing. Sixteen subjects reported walking pain during testing. All 17 subjects reported
Discussion
This study focused on possible differences in walking strategy between subjects with RA in FC II and healthy controls matched for gender and age, when the effect of differing speed on speed-dependent spatiotemporal gait variables had been taken into account.
The results supported the hypothesis that subjects with RA walk slower than healthy controls. This was in accordance with Fransen et al. [15] who studied subjects with RA aged 50–64 years. Thus, speed appears to be a useful discriminator
Conflict of interest
There are no conflicts of interests.
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