Windlass mechanisms - plural - and diabetes

[Gerrard Farrell]

These are extracts from a thread I have posted on Podiatry Arena . Any comments welcome .

Post 1

So during the gait cycle the windlass mechanism is engaged and reversed twice . Going from heel strike to heel strike we have windlass , reverse windlass , windlass and then reverse windlass at toe off . Yes ?


Post 2

So in this short clip we have windlass ,reverse windlass ,windlass ,reverse windlass ?

Haile Gebrselassie slowmotion left barefoot - YouTube

▶ 1:04

https://www.youtube.com/watch?v=Tek2JuRcO_w
6 Oct 2014 - Uploaded by Light Feet Running / Le Guide du Crawl Moderne
20kms de Paris 2017 : au ralenti, le passage de coureurs à 15km/h (4'/km) - Duration: 8:18. Light Feet Running ...

Gerrard Farrell

Glasgow



Post 3

So with regard to the above , the toe extensors contribute to arch stiffness during early stance by dorsiflexing the hallux and lesser toes and tensioning the plantar fascia . As stance progresses and ground reaction forces build , it seems likely that the prestrike , dorsiflexed position of the hallux/lesser toes will allow the plantar fascia and plantar intrinsics to load over a greater period of time reducing the stresses to which these tissues are subjected and so reducing the chances of plantar fasciitis developing .
Question .Can the first of the two windlass cycles during gait be significantly inhibited by footwear ?



Post 4

So the extensors contribute to foot stiffness .

In the case of a foot with intrinsic foot muscle atrophy caused by diabetic neuropathy , the foot likely becomes a less effective lever during gait , especially during late stance . Thus the musculo/neural/skeletal system may , through the information received by proprioception inputs , slowly adapt to the changing capabilities of the foot by causing gait to be altered in such a way as to reduce the work load of the forefoot during toe off . Hence a high stepping gait or a shuffling gait may develop .

However , I believe it is plausible that intrinsic muscle atrophy may also , in part , be compensated for by increased activity of the external toe EXTENSORS . Increased use of the toe EXTENSORS would tension the plantar fascia during midstance and late stance giving a more rigid lever and more proximal plantar pressures during these phases of stance .

Using the extensors in this way may lead to permanent extension of the proximal phalanges of the hallux and lesser toes , giving rise to cocked /claw toes . The fat pad under the met heads would migrate distally giving rise to pressure problems and ,over time the entire forefoot may start to curve upwards .

A cavus foot would also likely develop as the plantar fascia is tensioned by the extrinsic toe EXTENSORS to compensate for reduced plantar intrinsic input .

Could all of this be greatly helped by a podiatrist led ,conservative approach to the intrinsic foot muscles using an appropriately prescribed and supervised progressive resistance exercise program ?

Back to Dr Karen Mickle and her trial . "Evaluating a foot strengthening exercise program to improve foot function and foot health in older adults with diabetes"

What do you think ?

Regards
Gerry

Gerrard Farrell

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

Still on the general subject of the foot ,diabetes and the intrinsic foot muscles , the effects of exercise on peripheral artery disease (PAD) is well worth considering . Exercise has been shown to slow and even improve PAD although obviously the tissues served by a particular artery or group of arteries must be capable of being exercised to cause an increase in blood flow . In a foot with atrophied intrinsics , it follows that specific foot exercise will not be as effective at increasing blood flow in the foot arteries ( tibialis anterior ,tibialis posterior and the peroneal artery ), as exercises in a foot without atrophied intrinsics .( Note ; it is my understanding that exercises of the ankle do not increase blood flow to the foot itself but rather only to the tissues of the shank )

Thus maintaining adequate arterial supply to a foot with atropied intrinsics may be an uphill battle but may become easier if the intrinsics can be restored or preserved via progressive resistance exercise .

Any thoughts ?

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

So can footwear contribute to ongoing problems with plantar fasciitis ? I believe it can and that the problem may in part be due to the inhibition of the primary Windlass mechanism .

The primary Windlass mechanism ,as described in my previous posts on this thread , occurs just prior to, and during the weight acceptance phase of gait ,when the toe extensors first actively dorsiflex the toes ,prior to foot contact ,then eccentrically resist toe plantar flexion caused by ground reaction forces ,thus substantially reducing the forces the plantar fascia is subjected to . (loading of the fascia is more gradual )

So one question which has arisen in respect to this theory is , does the anatomy of the foot lend it's self to the mechanics suggested ?

Well ,I believe it does since the active tensioning component on the top (the extensor muscles ) and the passive band on the bottom (the plantar fascia ) are directly connected to each other via their attachments the the base of the proximal flange .

As a simple thought experiment think of a flexible . shatterproof 12 inch ruler with a small roller placed at one end . Now imagine a thin leather belt lying along the underside of the ruler ,over the roller and then back along the top of the ruler .Imagine also the base of the ruler and the underside section of the belt are fixed in place in a vice of some description . Ok ,now pull on the upper free end of the belt . The ruler will curve upwards .

However if you start off with a ruler which is already configured in an arch shape ,similar to the foot (apex uppermost) , then you will find that the arch deepens as you pull on the upper end of your belt .It will not invert back the other way . The arch / belt system will become better at resisting forces acting the straighten out the ruler -it is more rigid .

So it is with the arch of the foot ,the extensors and the plantar fascia .

So there are 2 windlass phases . A primary phase which involves active dorsiflexion of the toes before heel contact then plantar flexion during weight acceptance , and a secondary windlass phase which starts with passive dorsiflexion during later stance then moves to active plantarflexion of the toes during toe off .
The primary plantar phase is likely affected by footwear unless a spacious toe box is present .

If you have a primary Windlass phase as well as the accepted secondary Windlass phase ,then can the efficiency of the primary phase be improved by increasing the range of motion of the toes in dorsiflexion .
Might an increased range of motion of the toes produced by Rathleff's exercises be the key component of his treatment regime ?

High-load strength training improves outcome in patients with ... - NCBI

https://www.ncbi.nlm.nih.gov/pubmed/25145882

1. Similar

by MS Rathleff - 2015 - Cited by 39 - Related articles
Scand J Med Sci Sports. 2015 Jun;25(3):e292-300. doi: 10.1111/sms.12313. Epub 2014 Aug 21. High-load strength training improves outcome in patients with plantar fasciitis: A randomized controlled trial with 12-month follow-up. Rathleff MS(1), Mølgaard CM(2), Fredberg U(3), Kaalund S(4), Andersen KB(3), Jensen TT(4) ...

Gerrard Farrell

Glasgow

scotfoot, Yesterday at 6:30 PM






And Finally-

Here is a good slow motion film showing what I am presently calling the primary and secondary Windlass mechanism phases .

I have no idea who Ken Bob is , but bet he does not know he may have a fine example of a primary Windlass going on , which may be preventing excessive loading of his plantar fascia !
Barefoot Ken Bob slow-motion on treadmill - YouTube

▶ 0:40

https://www.youtube.com/watch?v=zIL07uYAW-Q
17 Aug 2010 - Uploaded by Ken Bob Saxton
Harvard University, Dr Daniel Lieberman's Skeletal Biology lab Note the subtle fore-foot landing. I'm not ...

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

I just came across a paper (1) on the long term prognosis for plantar fasciitis and its not good news for sufferers . In my opinion it would be well worth a group of qualified individuals looking into the existence and functioning of primary Windlass mechanism with regard to this type of debilitating pathology .

Here is part of the conclusion of the study -

Conclusion


"In patients with severe PF, the risk of still having PF was 50.0% after 5 years, 45.6% after 10 years, and 44.0% after 15 years from the onset of symptoms. Female patients and patients with bilateral heel pain had a significantly higher risk of having continuing symptoms. BMI, age, time from the onset of symptoms to baseline, smoking status, exercise-induced symptoms, and physical work had no significant impact on the prognosis in this study. The patients tried, on average, 3.8 different treatments, and a US-guided corticosteroid injection was the most frequently applied treatment (93%)."

Paper (1)
Long-Term Prognosis of Plantar Fasciitis: A 5- to 15-Year Follow-up Study of 174 Patients With Ultrasound Examination
Liselotte Hansen, MD, Thøger Persson Krogh, MD, PhD, Torkell Ellingsen, MD, PhD, ...
Orthopaedic Journal of Sports Medicine March 6, 2018

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

To better understand the impact that the primary Windlass mechanism would have in reducing stresses in the plantar fascia during the weight acceptance stage of gait , the following analogy may be of use .

. Imagine a simple 3 oz fishing weight hanging by a 2 foot long thread , from a tables edge . Now imagine lifting the weight upwards about 6 inches then dropping it again . Let's say the rapid loading of the thread causes the thread (representative of the the plantar fascia ) to snap . Now imagine you include a six inch piece of elastic in place of six inches of the thread ,so that the weight is now suspended at the end of a 1.5 foot long thread joined to six inches of elastic . Repeat lifting and dropping the weight and the thread is loaded less rapidly which protects the thread from damage . The elastic represents the toe extensor muscles connected to the plantar fascia via the bases of the proximal phalanges .

Thus , in my opinion , the primary or initial Windlass mechanism could make a great deal of difference to tissue loading during gait . To function properly the initial Windlass phase ( initial may be a better word than primary ?) is reliant on an adequate range of motion of the toes around the metatarsophalangeal joints , adequate strength in the toe extensors , appropriate neurological control , and non restrictive footwear where present ( Looking at the video above restrict footwear would be anything that significantly interfered with the movement of the foot )

Any thoughts ?

Gerrard Farrell

Glasgow
scotfoot

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

So here is a paper which confirms the pre-tensioning of the plantar fascia , pre heel strike , by way of activation of the toe extensors (1) P Caravaggi et al 2009 .

In my opinion , and in a counter intuitive twist , this pre-tensioning results in less tension in the plantar fascia during weight acceptance than would otherwise be the case .If you like , it prevents a rapid "tension transient" in the fascia during weight acceptance and ameliorates the potentially damaging effects of high levels of kinetic energy in the tissues of the foot as a whole .


An enlightening paper .

Quote -
"The simultaneous action of the ankle dorsiflexors and toe extensors, which prevent foot-slap and dorsiflex the toes at the MTPJ, and the plantarflexion moment applied to the calcaneus by the vertical ground reaction forces could account for some pre-stretching of the PA. A MTPJ dorsiflexion angle of about 30 deg. was measured for the three subjects thus confirming the action of the toe dorsiflexors at and prior to heel-strike (Table 4).
Indeed, a recent study has proposed that early stance preloading of the PA may be beneficial to propulsion during walking (Pataky et al., 2008). While the present study strongly suggests that such preloading exists, without further experimental and/or modelling studies, we can only speculate as to the possible advantages of such preloading. Loading the PA at heel-strike is likely to reduce the crimp present in unloaded collagenous tissues (Butler et al., 1978), thereby resulting in earlier arch stiffening and helping to ensure that, as the propulsive phase begins, a greater proportion of force is transferred by the foot to the ground."

Paper (1)
A dynamic model of the windlass mechanism of the foot: evidence for ...

jeb.biologists.org/content/212/15/2491
by P Caravaggi - 2009 - Cited by 60 - Related articles
This is the so-called windlass mechanism which, in the late phase of stance, is responsible for raising the arch of the foot (Hicks, 1954) and contributing to stiffening of the foot by pulling on the heel, causing inversion at the subtalar joint and `locking' the midtarsal joint (Briggs and Tansey, 2001). Previous studies using finite ...

Gerrard Farrell

Glasgow

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

Ok ,so now I am a bit confused .The plantar fascia is thought to support the arches of the foot during loading of the foot . However there seems to be a disconnect between the ground reaction forces shown to exists during weight acceptance (force plates ) and strain calculated to exist in the plantar fascia ,using cadaveric studies or finite models (see above ) , during the same stage . In my opinion it would appear that the models /cadaveric studies are significantly flawed .

Any thoughts ?

[Gerrard Farrell]

Re: Windlass mechanisms - plural - and diabetes

Here is a extract that may help with understanding the initial/primary phase of the windlass mechanisms --


EXTRACT

Imagine you have a rope wound around a drum a few times and then attached to a weight . Imagine also , that the rotation of the drum can be influence by an adjustable friction brake .
Ok , so now put the brake of full so that the drum does not turn at all . Throw the weight off the roof and as soon all the slack is taken up the rope will be pulled suddenly tight ,and if the weight is great enough and travelling fast enough , the rope will snap .

Now go back and adjust the brake on the drum so that it pays out line as desired . Now , when the weight drops and all the free line is used up , the drum can still rotate paying out more line against resistance bringing the weight to a more gradual stop . The drum and friction brake represent the initial engagement of the windlass and the eccentrically contracting toe extensors respectively .

I suppose another way of seeing the same thing would be the action of arrestor wires on an aircraft carrier . It's about kinetic energy and not just static forces .

Gerry
Gerrard Farrell

Glasgow
scotfoot, Mar 17, 2018