The full study protocol has already been published [16], and key components are reproduced here.

Study design

The multifaceted intervention for hallux valgus (MARVELL) trial was a parallel group, participant- and assessor-blinded, randomised pilot and feasibility trial over 12 weeks [17]. The study was registered with the Australian and New Zealand Clinical Trial Registry (ACTRN12621000645853), and the protocol was developed in consultation with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013 statement [18], the CONSORT 2010 statement extension to randomised pilot and feasibility trials [19], and items from CONSORT, as recommended by Thabane and Lancaster [20]. Ethical approval was obtained from the La Trobe University Human Ethics Committee (reference number: HEC20474).

Participants

Twenty-eight participants were recruited via from the northern suburbs of Melbourne, Victoria, Australia via postal invitation using a database of patients who received podiatry treatment at the La Trobe University Health Sciences Clinic, email distribution to staff members in the School of Allied Health, Human Services and Sport at La Trobe University, Facebook advertising and posters placed in the local community. To be eligible for inclusion, participants: (i) were aged ≥ 40 years, (ii) were female, (iii) had pain in the big toe joint/s (i.e. first metatarsophalangeal or interphalangeal) for at least 12 weeks, (iv) had big toe joint pain rated at least 3 out of 10 on a numerical rating scale, (v) were able to walk household distances (more than 50 m) unaided, (vi) were capable of understanding the English language, and (vii) had at least moderate hallux valgus on one or both feet [21]. Participants were not eligible for inclusion if they self-reported: (i) surgical treatment for hallux valgus on either foot, (ii) lower limb or partial foot amputation, (iii) an inflammatory rheumatological condition or connective tissue disease, (iv) a neurological disease which interfered with walking, (v) having worn arch-contouring foot orthoses in the past 12 weeks, (vi) having performed foot exercises in the past 12 weeks, or (vii) an injury of lower limb(s) or back that may interfere with reaching their feet.

Sample size

This was a pilot and feasibility trial, so was not fully powered to detect statistically significant differences between the groups. The recommended sample size for pilot studies is 12 people per group [22], however to allow for a 15% drop-out rate, we recruited 28 participants.

Recruitment and screening

Participants were recruited using postal invitation using a database of patients who had recently received podiatry treatment at the La Trobe University Health Sciences Clinic, email distribution to staff members in the School of Allied Health, Human Services and Sport at La Trobe University, Facebook advertising and posters placed in the local community. Potential participants were asked to contact the chief investigator (HBM) to express their interest and were then screened for eligibility by either of two members of the research team (HBM and PQXL).

Baseline assessments

Participant characteristics were collected by structured interview at the baseline assessment and included age, height, weight, country of birth, education level, major medical conditions, and medications. The following questionnaires and clinical assessments were also conducted: the Manchester scale for hallux valgus [21], foot pain characteristics [23], shoe-wearing history [10], the Incidental and Planned Activity Questionnaire [24] and the Credibility/Expectancy Questionnaire [25].

Randomisation

Permuted block randomisation (with block sizes of four, six and eight) was used to randomise participants on a 1:1 ratio to the control or intervention group using an online randomisation service (www.sealedenvelope.com).

Study procedure

All face-to-face assessments were performed in the Foot and Ankle Laboratory at La Trobe University, Victoria, Australia. Postal follow-ups were conducted at 4 and 8 weeks, with the final face-to-face follow-up at 12 weeks.

Blinding

Participants were blinded to group allocation by limited disclosure, in that they were told that the clinical trial was comparing two nonsurgical treatments for hallux valgus, but they were not informed about the specific characteristics of the treatments. Research staff administering the treatments could not be blinded. Outcomes were participant-reported, thus this study was also assessor-blinded (as participants were blinded). The study biostatistician performing the statistical analyses (BE) was blinded.

InterventionsControl group

The control group received a self-management package based on United Kingdom National Health Service recommendations [26] which advise people with hallux valgus to wear wide shoes with a low heel and soft sole, apply cold-packs and silicone gel bunion pads, and use paracetamol for pain relief. We provided all participants with cold-packs (Hot + Cold Therapy Gel Pack; OAPL, Clayton, Victoria, Australia) and silicone gel bunion pads (Spandex Gel™ Cushion Bunion Pads; Neat® Feat, Auckland, New Zealand). To meet ethical guidelines and aid retention, on completion of the study the control group participants were offered the same treatment as the intervention group.

Intervention group

The intervention group were provided with the same advice and self-management package as the control group, in addition to:

(i)

Footwear: high quality, off-the-shelf footwear (Anodyne #45 Sport Jogger; Global Footcare, Coomera, Queensland, Australia) (Fig. 1).

(ii)

Foot orthoses: prefabricated Formthotics™ (Foot Science International, Christchurch, New Zealand). These orthoses were three-quarter length and were constructed from dual-density, closed-cell polyethylene foam (Fig. 2). We used the three-quarter length as they are less likely to increase dorsal/medial pressure from footwear compared to the full-length devices [27], and used a heat-gun to warm the devices prior to fitting. No custom modifications were added.

(iii)

Foot exercises: participants were provided with access to a smart-phone app (PhysiTrack®, London, United Kingdom) which demonstrated a home-based version of the progressive resistance foot exercise program developed by Mickle et al. [14]. The set of 14 exercises (including four ‘warm-up’ and two ‘cool-down’ exercises) were performed three times per week for the 12 weeks. Each session took approximately 30 min to complete. Participants were contacted by the developer of the exercise program (KJM) to address any queries and ensure they were performing the exercises correctly. See Supplementary file for the list of exercises.

Fig. 1

Intervention footwear (Anodyne #45 Sport Jogger; Global Footcare, Coomera, Queensland, Australia). Reproduced from J Foot Ankle Res 2022;15:45

Fig. 2

Intervention foot orthoses (dual-density, three-quarter length Formthotics™). Image reproduced with permission from Foot Science International, Christchurch, New Zealand. Reproduced from J Foot Ankle Res 2022;15:45

Interventions were administered to both feet. Participants were free to use additional treatments during the study if they were documented in the 4-weekly postal surveys. However, participants were withdrawn from the study if they reported undergoing surgical intervention.

Primary outcome

The primary outcome was feasibility, which was evaluated according to demand, acceptability, adherence, adverse events and retention rate [28]. Demand was determined by the recruitment rate (participants recruited per month) and the conversion rate (participants providing consent divided by those who met the selection criteria). The recruitment rate was considered acceptable if six eligible participants were recruited per month, and the conversion rate was considered acceptable if ≥ 75% of those who were eligible participated. Acceptability of the intervention was determined using questions from the Monitor Orthopaedic Shoes (MOS) questionnaire [29] which addressed issues such as appearance, comfort, weight, and ease of donning and doffing. The intervention was considered acceptable if ≥ 75% of the intervention group scored more than 5/10 for each of questions 1–6. Adherence to the footwear/orthoses intervention was documented using 4-weekly diaries and objectively assessed over 12 weeks using a small temperature sensor embedded in the orthosis (Orthotimer®, Balingen, Germany) [30]. Adherence was considered acceptable if ≥ 75% of participants wore the footwear/orthoses for an average of ≥ 5 h per day over the 12-week follow-up period. Adherence to the exercise program was documented using 4-weekly diaries (or the PhysiTrack® smart-phone app) and was considered acceptable if ≥ 75% of participants attempted at least 66% of the total number of exercise sessions (i.e., 24 out of 36 sessions). In both the control and intervention groups, adherence to the hot/cold packs and bunion pads were measured using 4-weekly diaries. Adverse events were assessed at 4-weekly intervals via postal diary. Serious adverse events were defined as events that were life-threatening, required hospitalisation, or resulted in persistent or significant disability or incapacity [31]. The rate of adverse events was considered acceptable if < 15% and none were considered serious. Retention rate was the proportion of recruited participants who completed the 12-week outcome assessment. A ≥ 80% retention rate in each group was considered acceptable.

Secondary outcome

One of the secondary objectives was limited efficacy testing of the outcome measures. The key secondary outcome measure was the pain subscale of the Manchester-Oxford Foot Questionnaire (MOXFQ) [32, 33]. The minimum clinically important difference for the MOXFQ pain subscale is 12 points [34].

Other limited efficacy outcome measures included the MOXFQ [32] walking/standing and social subscales, measured at baseline and at 4-weekly intervals until 12 weeks, foot and ankle muscle strength, measured with a hand-held dynamometer using our previously documented, reliable protocol at baseline and week 12 [35], general health-related quality of life, assessed using Short Form (SF) 12 [36] measured at 4-weekly intervals, number of participants using co-interventions, documented at 4-weekly intervals, and participants’ perception of overall treatment effect, assessed with the question “Overall, how has your foot pain changed since the start of the study?” and using a global impression of change 15-point Likert scale response (ranging from ‘a very great deal worse’ to ‘a very great deal better’), measured at 12 weeks [37].

An acceptable feasibility outcome for the limited efficacy testing was a signal of efficacy for each continuously-scored outcome measure, as evidenced by at least a small effect size (Cohen’s d ≥ 0.20, calculated as the difference between the two group means divided by the overall standard deviation), less than 20% use of cointerventions in the intervention group, and a greater than 25% difference in the proportion of participants reporting at least ‘somewhat better’ on the perception of overall treatment effect compared to the control group.

Statistical analysis

As this was a pilot and feasibility study, it was not powered to detect changes in outcome measures, so the focus was not on inferential testing (although this was conducted) [17]. Descriptive statistics were used to report feasibility outcomes. Mean (SD) scores and mean differences (95% CI) were used to explore differences in continuous variables between the groups. Differences in the MOXFQ pain subscale between groups at 12 weeks (analysis of covariance, adjusted for baseline differences) were used to inform the sample size calculation for the main randomised trial.