Standardised classification system for bespoke thermoplastic ankle foot orthoses

A patient-centered 'test-drive' strategy for ankle-foot orthosis prescription: Protocol for a randomized participant-blinded trial

BACKGROUND

Ankle-foot orthoses (AFOs) are commonly used to overcome mobility limitations related to lower limb musculoskeletal injury. Despite a multitude of AFOs to choose from, there is scant evidence to guide AFO prescription and limited opportunities for AFO users to provide experiential input during the process. To address these limitations in the current prescription process, this study evaluates a novel, user-centered and personalized 'test-drive' strategy using a robotic exoskeleton ('AFO emulator') to emulate commercial AFO mechanical properties (i.e., stiffness). The study will determine if brief, in-lab trials (with emulated or actual AFOs) can predict longer term preference, satisfaction, and mobility outcomes after community trials (with the actual AFOs). Secondarily, it will compare the in-lab experience of walking between actual vs. emulated AFOs.

METHODS AND ANALYSIS

In this participant-blinded, randomized crossover study we will recruit up to fifty-eight individuals with lower limb musculoskeletal injuries who currently use an AFO. Participants will walk on a treadmill with three actual AFOs and corresponding emulated AFOs for the "in-lab" assessments. For the community trial assessment, participants will wear each of the actual AFOs for a two-week period during activities of daily living. Performance-based and user-reported measures of preference and mobility will be compared between short- and long-term trials (i.e., in-lab vs. two-week community trials), and between in-lab trials (emulated vs. actual AFOs).

TRIAL REGISTRATION

The study was prospectively registered at www.clininicaltrials.gov (Clinical Trials Study ID: NCT06113159). Date: November 1st 2023. https://classic.clinicaltrials.gov/ct2/show/NCT06113159.

A quantitative analysis of optimum design for rigid ankle foot orthoses: The effect of thickness and reinforcement design on stiffness

BACKGROUND

An ankle foot orthosis (AFO) which is prescribed to be rigid should only deform a small amount to achieve its clinical goals. Material thickness and the design of reinforcing features can significantly affect AFO rigidity, but their selection remains based on anecdotal evidence.

OBJECTIVES

To quantify the effect of these parameters on AFO stiffness and to set the basis for quantitative guidelines for the design optimisation of rigid AFOs.

STUDY DESIGN

Experimental and computational study.

METHODS

A polypropylene AFO was produced according to UK standard practice and its stiffness was experimentally measured for 30Nm of dorsiflexion. Its geometry and mechanical characteristics were utilised to create a finite element (FE) model of a typical AFO prescribed to be rigid. Following validation, the model was used to quantify the effect of material thickness and reinforcement design (i.e., reinforcement placement, length) on stiffness. A final set of AFO samples was produced to experimentally confirm key findings.

RESULTS AND CONCLUSIONS

For a specific AFO geometry and loading magnitude, there is a thickness threshold below which the AFO cannot effectively resist flexion and buckles. FE modelling showed that stiffness is maximised when reinforcements are placed at the anterior-most position possible. This key finding was also experimentally confirmed. The stiffness of an AFO reinforced according to standard practice with lateral and medial ribbing was 4.4 ± 0.1 Nm/degree. Instructing the orthotic technician to move the ribbings anteriorly increased stiffness by 22%. Further stiffening is achieved by ensuring the reinforcements extend from the footplate to at least two-thirds of the AFO's total height.

Satisfaction survey toward an innovative orthosis for children with cerebral palsy with pes planovalgus

BACKGROUND

Pes planovalgus (PPV) is common in children with cerebral palsy and can cause pain and gait alterations over time. Initial treatment of flexible PPV includes orthotics, despite a lack of consensus on the type of orthosis. We developed an innovative ankle-foot orthosis (RAFO). RAFO is a one-piece orthosis designed to correct both the valgus and the flat of the foot. Its conception situated above the malleolar enables a moderate anti equinus effect. Its precise description and fabrication's process is detailed.

OBJECTIVES

We wanted to assess user's satisfaction after several months of use and looked for clinical criteria of satisfaction.

STUDY DESIGN

Retrospective.

METHODS

We conducted a satisfaction study through a telephonic QUEST (Quebec User Evaluation of Satisfaction with Assistive Technology) survey analysing the device and the process in children and parents. 24 parents were contacted, whose child was wearing RAFO on a daily basis for at least 4 months. 20 parents answered the questionnaire. The results were then related to clinical data to research satisfaction' criteria.

RESULTS

Mean QUEST satisfaction was 4.25/5 (4.18/5 for device and 4.38/5 for process). Advantages reported concerned weight and dimensions (95%), although 20% reported the necessity to change to a shoe size above, ease of use (90%) and level of comfort (80%). Parent's satisfaction regarding perceived effectiveness was 80%. Children with equinus due to triceps surae spasticity were more susceptible to develop pain with our orthosis.

CONCLUSIONS

Parents were overall very satisfied with the orthosis. Its technical characteristics allowing both to be a corrector of flat foot and valgus and at the same time to be comfortable and discreet makes it innovative. The presence of spastic equinus is a limit for its utilization.