Foot Orthoses in Patients with Chronic Sciatica Caused by Lumbar Disc Herniation: a Randomized Clinical Trial

A multi-centre randomised controlled clinical trial has been designed according to the CONSORT guidelines. The design was carried out by the research group (5 researchers, Ph.D and Degree in Podiatry, from the University of Seville and 2 researchers, Medicine Doctors, from the university hospital "Virgen de Valme", in Seville, Spain). The patients will be diagnosed and recruited from the aforementioned hospital. The data will be gathered in the Clinical Area of Podiatry of the University of Seville.

The main inclusion criteria will be to have a medical diagnosis of chronic sciatica (CS) caused by lumbar disc herniation (LDH). All participants who voluntarily take part in the study will be given an informative document where the nature, objectives, and potential risks of the investigation are explained. When the participants have read it and any doubts have been resolved, the informed consent will be given for them to sign.

Firstly, clinical and demographic data will be collected, including age, gender, weight, height, years since diagnosis and current pharmacological management. Patients with CS will be explored and the Foot Posture Index (FPI) (a validated method for quantifying standing foot posture), and the Manchester scale for hallux valgus will be recorded for both the right and left foot. Plantar pressure will be obtained using the footscan® Advanced Pressure Measurement System (RsScan Lab LTD, UK). Standard podiatric care will be provided to the patients at the assessment session and when finished the follow up three months later, if needed. Participants will be requested not to have further foot interventions.

After the biomechanical examination, phenolic foam molds will be made of the patient's feet under weight-bearing conditions. The patient's foot will be manipulated before being introduced into the phenolic foam so as to place the subtalar joint in the most neutral position possible, always maintaining the forefoot plantar plane parallel to the ground. In the case of FPI values between +6 and +12, the examiner will hold the distal third of the participant's leg and apply external rotational force to the leg until the mirror of the pedoscope shows incipient loss of the first ray footprint that is, that the first metatarsal begins to elevate. At that moment, the examiner will stop applying external rotational force to the leg. The examiner will repeat this manoeuvre several times, as the external rotation applied to the foot in contact with the glass will be the same as that applied when introducing the foot into the phenolic foam. The same procedure but with internal rotation of the leg will be carried out for FPI values between -12 to -1. For feet with FPI values between 0 and +5, the examiner's hands will apply resistance against pronation or supination in order to maintain the foot in a normal posture.

For foot orthoses delivery one researcher will verify the fitting of the orthosis to the patient's foot. Then the orthosis will be set into shoes. Finally, the participants will be asked if the insoles cause them pain or discomfort in every session. Both interventions have the same protocol.