Trial Tests Carbon Fibre Inserts for Osteoarthritis Relief

BIRMINGHAM — A commonly used method by podiatrists and physiotherapists to manage osteoarthritis (OA) of the first metatarsophalangeal joint (MTPJ) is undergoing formal testing in a randomised clinical trial, a UK researcher said on the first day of The Primary Care Show 2025.

The Big Toe OstEoarthritis (BigTOE) Inserts Trial compares the use of a carbon fibre insert to stiffen shoes against a sham insole. The goal is to determine whether this approach can alleviate the pain associated with toe OA, said the trial’s chief investigator, Michael Backhouse.

Backhouse, who is a podiatrist and associate professor of clinical trials at Warwick University, told Medscape News UK, “The truth is, we don’t know if this approach works, which is why we are doing the trial.”

Lack of Evidence

Although carbon fibre inserts have been available and used within the NHS for years, there is very little evidence to show that these, or indeed any other insoles, actually do anything to help people with foot OA, according to Backhouse. As such, the National Institute for Health and Care Excellence (NICE) guidance on diagnosis and management of OA does not currently recommend their routine use. 

A survey of UK and Australian podiatrists and physiotherapists found over 50 different treatment approaches were being used to manage OA of the first MTPJ, which “reflects the lack of evidence,” Backhouse said. 

Helen Branthwaite, the newly appointed chief clinical advisor for the Royal College of Podiatry, told Medscape News UK, “What’s really unique about this trial is that they are going to have a multicentred population that will be randomised, so you don’t know which treatment you’re getting, which would address the psychological impact of the intervention.”

Branthwaite added, “Osteoarthritis of the first MP joint, or any joint, is progressive,” and the amount of pain experienced, or how long that lasts, depends on where a patient sits on a scale.

“When the joint completely fuses, you’ll have no pain at all. Clinically, we know that because we see that when we see patients and change the stiffness of their shoe,” added Branthwaite, who also works in private musculoskeletal podiatry practice in Macclesfield. 

Carbon fibre insoles are used to alter impact forces and improve joint mechanics, Branthwaite explained, highlighting that it was not just the quantity but the quality of data that was lacking on their use. 

The BigTOE Inserts Trial

The BigTOE Inserts Trial aims to provide quality evidence to support podiatrists’ individualised approaches. The target is to recruit 438 participants who have been screened at 25-30 general practice sites. Eligible participants must have a diagnosis of OA in the first MTPJ in one or both feet, experience activity-related pain in that joint that has been ongoing for at least 3 months, and be aged 18 years or older. 

Pain will be assessed on a numerical rating scale (NRS), where 0 is no pain and 10 indicates the worst pain. Participants have an activity-related pain NRS score of 4 or higher for inclusion. 

A comprehensive list of exclusion criteria has been put in place to ensure that patients with other musculoskeletal or inflammatory causes for their activity-related MTPJ pain are not included. This includes those experiencing pain predominantly on the plantar aspect of the joint, suggestive of sesamoid pathology; morning stiffness lasting for 30 minutes or more, or a clinical suspicion or previous diagnosis of inflammatory arthritis, connective tissue disease, septic arthritis, or crystal arthropathy. 

Also excluded are people with a history of surgery or clinically important trauma to the foot and ankle, or planned foot and ankle surgery within the next 12 months. Anyone who has had a corticosteroid injection in the affected foot within the past 3 months will be excluded, as will anyone who is identified as having moderate or severe grade 3 or 4 hallux valgus.

Finally, anyone who has used an insole prescribed by a healthcare professional in the past 3 months cannot be recruited. 

Pragmatic Approach

Backhouse described the trial design as “pragmatic.” “It reflects the patients you see in the clinic,” he said. As such, all participants will be given usual care, which involves tailored therapeutic exercise, advice on weight management, and provision of patient information and support as per NICE guidance. Additionally, they will be randomly allocated to receive either a carbon fibre insert or a sham insole. 

“We’re working with one supplier; the sham and the active insert appear the same,” Backhouse said. To ensure that patients do not know which device they are using, the carbon fibre component has been sandwiched between other layers of the insole. 

“We don’t tell them that we’re looking at carbon fibre inserts, and we don’t tell them that we’re looking at stiff inserts; we tell them we’re looking at inserts, maybe different materials,” said Backhouse.

The primary outcome will be the change from baseline in the Manchester Oxford Foot Questionnaire walking/standing subscale at 3 months, with additional assessments at 1, 6, and 12 months. This means that after the baseline assessment, no further clinic visits are required, and all questionnaires will be organised by the University of Warwick team.

“OA is common and disabling,” Backhouse noted. While generally diagnosed clinically without imaging, when imaging is used it suggests that around 17% of people over 50 years of age have foot OA. Moreover, three quarters of people with symptomatic radiographic OA reported disabling foot symptoms “that impacted on their daily lives.”

With “very limited evidence for treating OA,” the BigTOE Inserts Trial was one step towards changing that, Backhouse said. 

The BigTOE trial is funded by the National Institute for Health and Care Research. Backhouse and Branthwaite reported no relevant financial relationships. 

Sara Freeman, BSc, MSc, is a freelance medical journalist based in London, UK. She has been reporting for specialist healthcare news organisations for more than 20 years.