The Silicone Ankle Foot Orthosis (SAFO), a New Generation in Orthotics

Matthew Hughes, Orthotist/Prothetist
Dorset Orthopaedic Co Ltd

This paper is an introduction to a new and exciting development in the world of Orthotics the Silicone Ankle Foot Orthosis (SAFO). The idea of the paper is to outline the concept of the SAFO including patients treated, indications and a summary of the research carried out to date.

The presentation discusses five Cerebral Palsy patients that have been part of an ongoing case study through Yeovil NHS Trust in the UK over the last 9- 12 months, looking at visual clips, clinical outcomes and experiences and patient feedback.

The SAFO is a total contact silicone orthosis incorporating the foot and lower limb, it is reinforced down the anterior aspect of the leg and onto the dorsum of the foot, thus lifting the foot from above, as opposed to pushing from underneath as per traditional rigid AFO's. Due to the total contact around the foot and ankle it gives support without interfering with normal biomechanics and the prioprioceptive feedback is that things feel normal and the patient has control over their foot/feet.

Each SAFO is bespoke to a cast of the individual patients limb. A negative cast is taken ideally with the foot in approximately 0-5 degrees dorsiflexion. The positive mould is then reduced to set measures. Individual specifications are chosen by the orthotist e.g. No of straps, colour & reinforcements. Each SAFO is manufactured entirely from silicone.

SAFO Designs:



Patients Treated to Date:

  • Charcot Marie Tooth, CMT (HMSN).

  • Peripheral Neuropathies.

  • Trauma (peroneal and sciatic nerve).

  • Polio (below knee).

  • Incomplete Spinal Injuries.

  • Hemiplegia (CP children).

  • Multiple Sclerosis.

  • Diplegia (CP children).

  • Stroke (CVA).

Advantages of the SAFO over traditional rigid AFO's include:

  • Replicates normal foot action.

  • Normal alignment of ankle at mid-stance.

  • Reduced global spasticity (where approriatp)

  • Reduced risk of pressure areas.

  • Fits into normal footwear.

  • Can be worn without footwear.

  • Can be worn for showering/swimming.

  • Little Maintenance.

  • Easy to don/doff.

  • Cosmesis.

Cerebral Palsy Trial 2004-2005

The trial, conducted over 12 months between October 2004 and October 2005, examined the clinical and functional benefits of using the Silicone Ankle Foot Orthosis (SAFO) as an alternative to the more traditionally prescribed rigid Ankle Foot Orthosis in children and young adults aged 7 – 16. The Senior Paediatric Physiotherapist from Yeovil NHS Trust in the UK selected all patients. The children presented as follows:

  • High –Tone Rt Hemiplegic, aged 12.

  • Low – Tone Diplegic, aged 12.

  • High – Tone Rt Hemiplegic, aged 12.

  • Spastic Diplegic, aged 7.

  • High – Tone Rt Hemiplegic, aged 16.

All patients attended our Orthotic clinic in Ringwood Uk to be assessed and cast/measured for the SAFO's, following this the deliveries and all reviews were also held at the clinic. All the patients chosen had worn a variety of orthotics in the past with mixed results.

The patients were filmed and monitored before and after fitting of their new SAFO's and at 3 monthly intervals over the 12-month trial in order to record the mobility and behaviour change. Video footage of these stages will be shown during the presentation to further enhance the results that are to be discussed.

Key measurements and observations for all participants were taken under the following indicators:

  • Range of active and passive foot movement.

  • Body posture.

  • Gait.

  • Balance.

  • Walking speed and endurance.

  • Skin condition.

(All of which will be discussed in more detail during the presentation)

Each of the 5 patients taking part in the trial showed significant improvements against each indicator. Children were able to go up and down stairs and take part in sports and play activities in a way that had not been possible with any previous treatment. Importantly, compliance was 100%, with each child happily wearing the SAFOs daily in school/college.

At the initial assessment for all of these patients there were question marks raised by many as to the appropriateness of the SAFO as a treatment plan, however the patient and parent testimonials in conjunction with the observed differences from a clinical perspective using video data and clinical tests has served to show that the SAFO does indeed have a place in the treatment of patients suffering from differing forms of Cerebral Palsy.

This is undoubtedly a small group of children and further research needs to be done to quantify the observed improvements during this 12-month period nonetheless a new era in dynamic orthotic splinting is upon us. Minimum orthotic input, to allow maximum functional output.

Previous SAFO Research to date:

Establishment: Salisbury District Hospital, Salisbury Wiltshire
Investigator: Professor Ian Swain, Department of Medical Physics & Biomedical Engineering
Study title: The use of a silicone boot orthosis on the speed and effort in walking in patients with lower motor neuron lesions.
Presented: The 10th World Congress of the International Society for Prosthetics & Orthotics, 1st July 2001
Method: 12 subjects with lower motor neuron lesions were fitted with the orthosis. Walking speed and Physiological Cost Index (PCI, effort of walking) were then individually measured and analysed using Wilcoxon signed ranks test. This was carried out initially and after 6 months use. All patients completed a questionnaire.
Findings: Comparison of walking speed and PCI at 6-month assessment with the orthosis compared to the initial assessment without showed an increase in speed of 20% and a reduction of PCI of 32%.

Establishment: Strathclyde University Hospital
Investigator: Peter McLachlan B.Sc (Hons)
Study title: Comparision of Silicone Ankle Foot Orthoses versus Plastic Ankle Foot Orthoses in subjects with lower motor neuron lesions using the CODA mpx30 gait analysis system.
Presented: The 11th World Congress of the International Society for Prosthetics & Orthotics, August 1-6 2004 Hong Kong
Method: 6 subjects were selected who had been previously supplied with AFO's. They were then assessed, cast and fitted for a custom made SAFO. They wore the SAFO for a minimum of 4 weeks. They then returned for gait analysis unbraced, with AFO and with SAFO.
Findings: Results showed that the AFO had a greater dorsiflexion on swing through, however there was less knee and hip flexion, with the SAFO on during swing phase. The SAFO also produced a smoother transition from heel strike – foot flat.