Windlass Mechanism

Looking through other blogs and I came across this post from physioblogger:

Its a interesing piece about the Windlass Mechanism and how to assess it, so I thought I’d share it.

The Theory of the Windlass Mechanism

The theory behind the Windlass Mechanism has been around for about 50-60 years and is a very mechanical thought process. It’s pretty cool and fits into my thought process of the foot loading and exploding really well. In almost everything I do and write about I think of the loading and exploding of gait. The foot will try and complete many tasks during gait, but there are two key ingredients to successful foot function. Firstly, the foot needs to be relatively flexible during the loading phase, in order to effectively absorb the landing forces and adapt to the surface. And secondly, become relatively rigid during the propulsive, exploding phase of gait. This is in order that there is effective transfer of force into the desired direction of travel and that the forces involved are transferred through the appropriate tissues/structures to protect the more sensitive ones.

This mechanism allows for both of these to be achieved and uses a lever (the big toe), a pivot (first metatarsal head) and a tensile structure (the plantar fascia) to allow for the flexible loading and the rigid exploding. The foot can be described in terms of it’s arches (I think there are 3?), with the windlass mechanism taking advantage of the medial longitudinal arch.

While the foot is loading and adapting to the ground surface the big toe is in a relatively neutral position, leaving less tension in the plantar tissues and allowing them to load. The joints of the foot go through pronation, the soft tissues load and are now ready to go through supination.

On the right hear you can see a simplified version of the mechanism and on the left you can see the mechanism in the foot itself.

Obviously, in function it is the foot going over the toe rather than the toe extending over the foot that creates the mechanism, this can be seen in the picture below. Here you can see the foot coming over the toes, tensioning the plantar fascia and drawing the calcaneus towards the metatarsal heads.

There are many mechanisms that contribute to the supination of the foot. however, the windlass mechanism plays a key role. You can see in the picture how the extension of the big toe tensions the plantar fascia and draws the calcaneus towards the metatarsal head, raising the arch and assisting in re-supinating the foot. This supination decreases/locks the motion in the mid tarsal joint stabilising the foot for the explode. If this does not occur it is possible that the patient is more vulnerable to injury, for example, Plantar Fasciitis.


Assessing the Windlass Mechanism

I personally only know one way of assessing the windlass mechanism. It’s pretty simple. You ask the patient to stand in front of you and relax. You manually extend their big toe and observe the medial arch of the foot to see if the arch raises with the big toe extension. If it does then I am satisfied it can work (at least statically) and if it doesn’t I may need to investigate further. For example, you may try to position their foot (in sub talar neutral for example) and re-test to see if it capable of working. If it is capable of working you may try treating to to achieve the appropriate foot position in function so it can work. Or if that is not possible, you may try an orthotic to help position the foot for better function.

Summary

Overall I feel this is a great explanation of a complex theory but most interestingly is that Neil at Physioblogger feels the mechanism is a distal-to-proximal trigger whereas it may be assumed in the past and from other reading that it is muscle activity reaction from proximal to distal. I hope this has been beneficial.

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TA Physio

am driven and passionate about healthcare focused on delivering successful patient outcomes through personalised rehabilitation. So far, I have established a successful career in physiotherapy rehabilitation and gained valuable experience in contributing to marketing strategies within multi-national companies. In 2005 I graduated from UWIC with a degree in science, health, exercise and sport, and then specialised in Physiotherapy and graduated Coventry University in 2008. Since commencing my physiotherapy career I have gained valuable experience in musculoskeletal, sports rehabilitation, and community based neurological and falls prevention rehabilitation within the NHS. In 2010 I set up TA Physio to provide a personal and flexible service for clientele requiring sports rehabilitation, falls prevention & rehabilitation, musculoskeletal physiotherapy as well as bio mechanical assessment in North London. In 2011 I joined AposTherapy as a junior therapist and developed over 2 years to become a Senior AposTherapist in 2013. Recently I have been promoted to lead the London Clinic development and growth reporting directly to the UK Clinical Lead and overseeing ten members of clinical staff. The responsibilities included developing vital HCP links to build referral pathways, accountable for staff development and clinical needs of the AposTherapy London Clinic. In 2014 I provided physiotherapy to elite athletes at The Glasgow 2014 Commonwealth Games. I was based within the busy and dynamic polyclinic within the Athletes' Villages. The aim is to help Glasgow 2014 deliver a direct access physiotherapy service to the people at the heart of the Games. Specialties: Gait Analysis, Deviations and Gait Rehabilitation; Sports Specific Rehabilitation; Orthopaedic Post Operative Rehabilitation; Musculoskeletal Physiotherapy; Clinical Blog Writing; Development and Growth of Clinical Services; Presenting to Healthcare Professionals & Advisory Boards.