Three Foot Orthosis Interventions for Progressive Collapsing Foot Deformity

Overview

Background Progressive collapsing foot deformity (PCFD) is a painful musculoskeletal disorder leading to a progressively developing flat foot, which affects mobility and function and negatively impairs quality of life. Foot orthoses (FOs) are often prescribed to attenuate pain and improve function in patients with PCFD. However, no study has yet investigated the impact of adding FOs, whether custom (CFOs) or prefabricated (PFOs), to the usual treatment for PCFD. Thus, the primary objective of this trial will be to compare three different non-surgical interventions combining foot exercises and education with either CFOs, PFOs or sham FOs (SFOs). Methods/Design This participant-blinded multicentric superiority randomized controlled trial with three parallel groups will be conducted at the Université du Québec à Trois Rivières (UQTR) and the Center for Interdisciplinary Research in Rehabilitation and Social Integration (Cirris) in Canada. One hundred and ninety-eight participants with PCFD will be recruited via referral from physiotherapy and podiatry clinics and targeted advertising on social media. Participants will be randomized to receive CFOs, PFOs or SFOs. All groups will also receive a foot and ankle exercises program and education about their condition. They will be evaluated at four time points: baseline, 12 weeks, 24 weeks and 52 weeks. The primary outcome will be the subcategories of pain from the Foot Function Index (FFI) questionnaire. The secondary outcomes will be: foot pain and limitations (other categories of FFI, mean and maximal pain during walking for the most painful foot during the past week), self-assessed clinical progress (Global Rating Of Change), health-related quality of life (5-Level EQ-5D), gait biomechanics, fear avoidance (Fear avoidance Scale), supination resistance and ankle and hip endurance and force. Discussion This trial first aims to determine whether FOs treatment is effective, and second, whether one of the three FO interventions is more effective than the others. This trial will help guide FOs prescription recommendations for managing foot pain, function, and biomechanical outcomes in individuals with PCFD in the future.

Progressive collapsing foot deformity (PCFD) was historically described under the terminology posterior tibial tendon dysfunction (PTTD), later expanded through the adult acquired flatfoot deformity (AAFD) framework, before being reclassified in 2020 as PCFD to better reflect its progressive, multiplanar nature. Beyond pain, PCFD carries substantial functional and social consequences: patients report marked difficulty with activities such as climbing stairs, walking fast, or running, along with challenges finding comfortable or fashionable footwear, all of which negatively affect quality of life. These functional limitations are caused by specific gait alterations, including increased forefoot abduction, greater hindfoot eversion and internal rotation, reduced ankle inversion and dorsiflexion, and a medial shift in plantar pressure during walking. Foot orthoses (FOs) are thought to counteract these alterations: a systematic review found that most studies report improvements in kinetics, and kinematics following FO use. These biomechanical effects have supported the widespread clinical use of FOs as part of first-line conservative management for PCFD. However, whether these biomechanical improvements translate into a clinical benefit specifically attributable to FOs remains unclear. In all prior RCTs reporting pain and functional improvements with FOs in this population, orthoses were provided as part of a broader multimodal program that also included education and exercise therapy, meaning the additional contribution of FOs alone has never been isolated. Furthermore, no RCT has directly compared custom CFOs and PFOs in individuals with PCFD. A recent retrospective cohort analysis reported meaningful pain reduction and functional improvement with CFOs, but the absence of a control group limits the extent to which this improvement can be attributed to the orthotic intervention itself rather than to natural symptom evolution. By comparing CFOs, PFOs, and SFOs against a common background of standardized education and exercise, this randomized controlled trial design will allow us to determine whether, beyond their known biomechanical effects, FOs provide an additional clinical benefit for individuals with PCFD, and whether this benefit differs according to orthosis design.