Elsevier

Clinical Biomechanics

Volume 29, Issue 3, March 2014, Pages 350-353
Clinical Biomechanics

Brief report
The effects of sandals on postural stability in patients with rheumatoid arthritis: An exploratory study

https://doi.org/10.1016/j.clinbiomech.2013.12.006Get rights and content

Abstract

Background

Rheumatoid arthritis results in postural instability, pain and functional limitations. As rheumatoid arthritis progresses, localised forefoot deformities such as hallux valgus and clawing of the lesser toes occur, leading to a high proportion of people with rheumatoid arthritis wearing sandals. Sandals may affect postural stability due to poor motion control. The aim was to assess two different open-toe sandals on postural stability in people with rheumatoid arthritis.

Methods

Twenty women with rheumatoid arthritis were assessed in quiet standing under four conditions: (1) open-back sandal; (2) closed-back sandal; (3) own footwear and (4) bare feet. Postural stability was assessed as postural sway in the anterior-posterior and medial-lateral directions, with eyes open and eyes closed, using a pressure mat. Repeated measures analysis of variance tested the interaction effect of the footwear and eye conditions on anterior-posterior and medial-lateral sway.

Findings

In eyes-open, there was no significant difference in anterior–posterior sway (P = .169) and medial-lateral sway (P = .325) for footwear conditions. In eyes-closed testing, compared with barefoot conditions, increased anterior–posterior sway was observed with participants' footwear (P < .0001), the open-back sandal (P = .005), and the closed-back sandal (P = .017). With eyes closed, increased anterior–posterior sway was also observed with the participants' footwear compared with the closed-back sandal (P = .041). Increased medial-lateral sway was observed with the closed-back sandal compared with bare feet (P = .014).

Interpretation

Sandals may be detrimental to older women with well-established rheumatoid arthritis when eyes are closed. Further investigation is needed to evaluate the effect of sandals on dynamic tasks.

Introduction

Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory, joint disease affecting 0.5 to 1.0% of the world population (Scott et al., 2010). The foot is a common site of pathology in early RA and forefoot involvement becomes greater with disease progression (Michelson et al., 1994, Wiener-Ogilvie, 1999). Control of balance, or postural stability, is essential in all static and dynamic activities. A previous study reported that static postural stability, in the anterior–posterior centre of pressure excursion during the eyes open task and the eyes closed task is decreased in RA compared to the non-RA population (Rome et al., 2009a). As a result, people with RA may have difficulty maintaining postural control leading to balance problems in everyday activities (Rome et al., 2009a).

Footwear has a role to play in postural stability by facilitating somatosensory feedback to the foot by the proprioceptive system that detects and processes tactile stimulation/information (Brenton-Rule et al., 2011, Hijmans et al., 2007, Perry et al., 2007). Cutaneous mechanoreceptors, located in the plantar surface of the feet, detect tactile stimuli and provides the central nervous system (CNS) with information regarding plantar pressure distribution (Hijmans et al., 2007). This is important, as changes in foot pressure are often related to changes in an upright position (Kavounoudias et al., 1998). Footwear may also control foot motion, thus potentially affecting foot function and balance (Barton et al., 2009, Menz and Lord, 1999). Previous studies in the older adult population have reported that poor footwear type and poor footwear characteristics lead to postural instability (Brenton-Rule et al., 2011, Keegan et al., 2004, Sherrington and Menz, 2003). Sherrington and Menz (2003) reported unsafe features of shoes identified included excessively flexible heel counter and an excessively soft sole. Furthermore, Keegan et al. (2004) found that slip-on shoes and sandals were associated with a greater risk of a foot fracture from a fall.

Sandals have been found to be worn by the majority of patients in two recent studies from New Zealand of people with RA (Rome et al., 2009b, Silvester et al., 2010). It is possible that people with RA wear open-type sandals in order to better accommodate forefoot deformity associated with the disease such as clawing of the lesser digits and severe bunions. However, sandals may have a detrimental effect on balance due to poor footwear characteristics such as minimal heel counter stiffness and poor motion control. Variation in sandal design includes backless (no back-strap), open-back (back-strap only) and closed-back (full heel counter). Laboratory based research into the effect of heel counter stiffness on postural stability is not evident in the literature. However, heel counter stiffness is thought to be important in rear foot control and a stiff heel counter may provide mechanical support to the foot (Barton et al., 2009). Flimsy or excessively flexible heel counter has also been associated with falls in older adults (Finlay, 1986, Sherrington and Menz, 2003). Therefore, the aim of the current study is to evaluate the effect of open-back and closed-back sandals, in relation to postural stability, in women with established RA.

Section snippets

Methods

Twenty participants were recruited from a rheumatology outpatient clinic in Auckland, New Zealand. The study was approved by the Auckland University of Technology Ethics Committee and participants provided written informed consent. Inclusion for the study was women older than 18 years with a diagnosis of RA (Aletaha et al., 2010). People were excluded from the study if they had a neurological condition which could impair balance (including history of stroke, multiple sclerosis and Parkinson's

Results

Participant characteristics are presented in Table 1. All participants were female and 90% were European, with mean (SD) age of 68 (12) years. The mean (SD) RA disease duration was 22 (12) years. Ninety percent of participants had radiographic erosions in the feet. On the day of the study visit, participants had moderate disease activity and disability, with mean (SD) scores: DAS28-ESR 3.68 (1.01), DAS28-CRP 3.74 (1.75), HAQ-II 1.01 (0.42). Participants reported high to severe levels of foot

Discussion

The aim of the study was to evaluate the differences between two types of open-toe sandal, participants' own footwear and bare feet, in relation to postural stability in women with established RA. The population tested had longstanding disease, moderate disease activity and disability, and high to severe foot impairment. Forty percent of participants wore open-toe sandals to the study visit. This was higher than previous studies of RA patients, in which 21% (Rome et al., 2010) and 33% (

Conclusion

The current study found that open-toe sandals did not significantly affect balance in quiet standing, in eyes-open test conditions, in older women with well-established rheumatoid arthritis. In addition, there was no significant difference in postural sway between open-back and closed-back sandals in eyes-open or eyes-closed test conditions. However, in eyes-closed testing, postural sway was significantly increased in all footwear types compared to bare feet. These findings suggest that

Disclosure statement

All authors have declared no conflict of interest.

Acknowledgements

KR, ABR, ND and MC designed the study. SD collected the data. ABR and SB conducted the statistical analysis. All authors were involved in the draft and final version of the manuscript. Dr Michael Corkill, for training SD in assessing joints for tenderness and swelling and reviewing the manuscript. SD was supported through a summer studentship research grant from Arthritis New Zealand.

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