Chuter et al. BMC Musculoskeletal Disorders (2016) 17:468 DOI 10.1186/s12891-016-1327-x RESEARCH ARTICLE Open Access Flip-flop footwear with a moulded foot-bed for the treatment of foot pain: a randomised controlled trial Vivienne Helaine Chuter1,2, Angela Searle1* and Martin J. Spink1 Abstract Background: Foot pain is a common problem affecting up to 1 in 5 adults and is known to adversely affect activities of daily living and health related quality of life. Orthopaedic footwear interventions are used as a conservative treatment for foot pain, although adherence is known to be low, in part due to the perception of poor comfort and unattractiveness of the footwear. The objective of this trial was to assess the efficacy of flip-flop style footwear (Foot Bio-Tec©) with a moulded foot-bed in reducing foot pain compared to participant’s usual footwear. Methods: Two-arm parallel randomised controlled trial using computer generated random allocation schedule at an Australian university podiatry clinic. 108 volunteers with disabling foot pain were enrolled after responding to an advertisement and eligibility screening. Participants were randomly allocated to receive footwear education and moulded flip-flop footwear to wear as much as they were comfortable with for the next 12 weeks (n = 54) or footwear education and instructions to wear their normal footwear for the next 12 weeks (n = 54). Primary outcome was the pain domain of the Foot Health Status Questionnaire (FHSQ). Secondary outcomes were the foot function and general foot health domains of the FHSQ, a visual analogue scale (VAS) for foot pain and perceived comfort of the intervention footwear. Results: Compared to the control group, the moulded flip-flop group showed a significant improvement in the primary outcome measure of the FHSQ pain domain (adjusted mean difference 8.36 points, 95 % CI 5.58 to 13.27, p < 0.01). Statistical and clinically significant differences were observed for the secondary measure of foot pain assessed by a VAS and the FSHQ domains of foot function and general foot health. None of the participants reported any pain or discomfort from the intervention footwear and six (footwear group = 4) were lost to follow up. Conclusions: Our results demonstrate that flip-flop footwear with a moulded foot-bed can have a significant effect on foot pain, function and foot health and might be a valuable adjunct therapy for people with foot pain. Trial registration: ACTRN12614000933651. Retrospectively registered: 01/09/2014. Keywords: Shoes, Pain measurement, Health status indicators Background In the middle aged and older population, foot pain is more Foot pain is widely acknowledged to be a common prob- prevalent in females, the forefoot and toes are the most lem. A recent systematic review involving 75,000 adults common site of pain, and in two thirds of cases this re- found that approximately 1 in 5 people over 45 years of sults in a moderate disability in an aspect of daily life [1]. age experience ‘frequent’ foot pain [1], and a UK survey of The community burden of foot pain is high and is known 3,417 adults reported 24 % of females and 20 % of males to adversely affect activities of daily living [2], reduce had foot pain in the last month lasting at least 1 day [2]. health related quality of life (QOL) [3], impair balance and functional ability in community dwelling older people [4], * Correspondence: [email protected] and increase risk of falls in older people [5, 6]. 1School of Health Sciences, The University of Newcastle, 10 Chittaway Road, Footwear interventions are widely used as a conservative PO Box 127, Ourimbah, NSW 2258, Australia treatment method for foot pain [7, 8]. The orthopaedic Full list of author information is available at the end of the article © The Author(s). 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Chuter et al. BMC Musculoskeletal Disorders (2016) 17:468 Page 2 of 8 footwear usually recommended is a closed in lace-up style and the person administering the intervention (VC) were shoe and adherence to this intervention is known to be as not blinded as they were aware of what type of shoe they low as 22 %, with perceived poor comfort and unattract- were wearing. The person conducting data analysis (MS) iveness of the footwear cited as the main-reasons for non- was blinded to group allocation. adherence [8, 9]. Flip-flop style footwear has not been considered as a treatment modality for foot pain as it is Participants believed to provide less support, protection, cushioning Potential participants were recruited on a volunteer basis and motion control compared to closed-in shoes [10–12]. via advertising flyers at the University of Newcastle The introduction of new design features in flip flops such Central Coast Campus and the University of Newcastle as moulded foot-beds, increased sole thickness and a heel- Podiatry Clinic at Wyong Hospital. Inclusion criteria to-forefoot slope allows them to provide some of the func- were adults, 18 years of age and over with disabling foot tionality of closed in shoes [13, 14]. Despite the popularity pain, which was defined as current foot pain located of flip-flop style of footwear, there is very limited evidence below the level of the ankle joint which prevented them regarding the effect these design features have on foot from doing at least one of their normal activities. Exclu- pain and foot function, with only one study investigating sion criteria were history of foot amputation, current the use of a contoured sandal for treating plantar heel pain foot pain due to arterial insufficiency, venous insuffi- [15]. This study found the sandal provided a similar bene- ciency or peripheral neuropathy of any cause, a neurode- ficial reduction in pain compared to a contoured shoe in- generative disorder or a history of two or more falls in sert, and that both the sandal and the shoe insert provided the previous 12 months. All potential participants re- a significant reduction in pain compared to a flat flip flop. ceived a participant information statement and were The aim of this study was to investigate the efficacy of screened via a short phone call to ensure inclusion and flip-flop style footwear with a moulded foot-bed in redu- exclusion criteria were met. Any participants reporting cing foot pain and improving function compared to usual medical history associated with the exclusion criteria relat- footwear in adults with disabling foot pain. We also ing to peripheral arterial disease, venous insufficiency or assessed the effect of the footwear on perceptions of gen- peripheral neuropathy underwent additional screening in- eral foot health and comfort. cluding visual examination, continuous wave Doppler and/or a four site 10 g monofilament test [17, 18]. Pres- Methods ence of a monophasic waveform or loss of sensation at Design and trial registration one site was considered indicative of pathology [17, 18] The study was a two-arm parallel group randomised and the potential participant was excluded. History of falls controlled trial with a 12 week follow up period and is in the last 12 months was confirmed through verbal ques- reported using CONSORT guidelines [16]. The trial has tioning. At their first appointment participants completed been registered on the Australian New Zealand Clinical the consent form before being enrolled in the trial. Trials Registry (ACTRN12614000933651). All participat- ing patients gave their informed consent. Research was conducted at the University of Newcastle Podiatry Clinic Intervention at Wyong Hospital. Participants in the intervention group were fitted with a pair of flip flops (Foot Bio-Tec©, Silverwater, NSW, Randomisation and blinding Australia) with a moulded foot-bed, heel cup and wide After enrolment participants completed a set of baseline straps (Fig. 1), and asked to wear the footwear as much questionnaires to determine their foot pain and foot as they were comfortable with for the next 12 weeks. function. Participants were then randomised into either Participants in the control group were asked to wear an intervention group that received a pair of test foot- their usual footwear for the next 12 weeks. Both the wear and footwear education or a control group that re- control and intervention groups received general advice ceived footwear education only. Prior to recruitment AS on footwear including choosing footwear of an appropri- prepared sequentially numbered, opaque sealed enve- ate size and fit, with firm fastening, low heel height and lopes containing a computer generated random alloca- slip-resistant soles. Participants who received the test tion schedule with mixed block lengths of four and six footwear were asked to complete a daily footwear diary participants. The person administering the intervention to record how often and for how long they wore the (VC) enrolled participants and assigned participants to intervention footwear. At the conclusion of the trial groups by selection of the next sequential envelope. Stat- participants were asked if they had undertaken any istical analysis was performed independently by MS. All other treatment for their foot pain during this time outcome data was collected using self-reported question- and if the intervention footwear had caused any pain naires completed by the participants. The participants or discomfort.