Functional Ankle Instability and the Peroneals

Lots of links available here with today’s blog post. please make sure to take your time and check out each one (underlined below) 

As you remember, the peroneii (3 heads) are on the outside of the lower leg (in a nice, easy to remember order of longus, brevis and tertius, from top to bottom) and help to stabilize the lateral ankle. The peroneus brevis and tertius dorsiflex and evert the foot while the peroneus longus plantarflexes and everts the foot. We discuss the peroneii more in depth here in this post. It then is probably no surprise to you that people with ankle issues, probably have some degree of peroneal dysfunction. Over the years the literature has supported notable peroneal dysfunction following even a single inversion sprain event. 

Functional ankle instability (FAI) is defined as “ the subjective feeling of ankle instability or recurrent, symptomatic ankle sprains (or both) due to proprioceptive and neuromuscular deficits." 

Arthrogenic muscle inhibition (AMI) is a neurological phenomenon where the muscles crossing a joint become "inhibited”, sometimes due to effusion (swelling) of the joint (as seen here) and that may or may not be the case with the ankle (see here), or it could be due to nociceptive input altering spindle output or possibly higher centers causing the decreased muscle activity. 

This paper (see abstract below) merely exemplifies both the peroneals and FAI as well as AMI.

Take home message?

Keep the peroneals strong with lots of balance work!                                                             

2009 May;37(5):982-8. doi: 10.1177/0363546508330147. Epub 2009 Mar 6.

Peroneal activation deficits in persons with functional ankle instability.

Palmieri-Smith RM, Hopkins JT, Brown TN.

Source

School of Kinesiology, University of Michigan, 401 Washtenaw Avenue, Ann Arbor, MI 48109, USA. riannp@umich.edu

Abstract

BACKGROUND:

Functional ankle instability (FAI) may be prevalent in as many as 40% of patients after acute lateral ankle sprain. Altered afference resulting from damaged mechanoreceptors after an ankle sprain may lead to reflex inhibition of surrounding joint musculature. This activation deficit, referred to as arthrogenic muscle inhibition (AMI), may be the underlying cause of FAI. Incomplete activation could prevent adequate control of the ankle joint, leading to repeated episodes of instability.

HYPOTHESIS:

Arthrogenic muscle inhibition is present in the peroneal musculature of functionally unstable ankles and is related to dynamic peroneal muscle activity.

RESULTS:

The FAI patients had larger peroneal H:M ratios in their nonpathological ankle (0.399 +/- 0.185) than in their pathological ankle (0.323 +/- 0.161) (P = .036), while no differences were noted between the ankles of the controls (0.442 +/- 0.176 and 0.425 +/- 0.180). The FAI patients also exhibited lower EMG after inversion perturbation in their pathological ankle (1.7 +/- 1.3) than in their uninjured ankle (EMG, 3.3 +/- 3.1) (P < .001), while no differences between legs were noted for controls (P > .05). No significant relationship was found between the peroneal H:M ratio and peroneal EMG (P > .05).

CONCLUSION:

Arthrogenic muscle inhibition is present in the peroneal musculature of persons with FAI but is not related to dynamic muscle activation as measured by peroneal EMG amplitude. Reversing AMI may not assist in protecting the ankle from further episodes of instability; however dynamic muscle activation (as measured by peroneal EMG amplitude) should be restored to maximize ankle stabilization. Dynamic peroneal activity is impaired in functionally unstable ankles, which may contribute to recurrent joint instability and may leave the ankle vulnerable to injurious loads.

Pain on the outside of one leg, inside of the other. 

Whenever you see this pattern of discomfort, compensation is almost always at play and it is your job to sort it out. 

This patient presents with with right sided discomfort lateral aspect of the right fibula and in the left calf medially. Pain does not interfere with sleep.  He is a side sleeper 6 to 8 hours. His shoulders can become numb; left shoulder bothers him more than right.

PAST HISTORY: L shoulder surgery, rotator cuff with residual adhesive capsulitis. 

GAIT AND CLINICAL EVALUATION: see video. reveals an increased foot progression angle on the right side. Diminished arm swing from the right side. A definite body lean to the right upon weight bearing at midstance on that side.

He has external tibial torsion bi-lat., right greater than left with a right short leg which appears to be at least partially femoral. Bi-lat. femoral retrotorsion is present. Internal rotation approx. 4 to 6 degrees on each side. He has an uncompensated forefoot varus on the right hand side, partially compensated on the left. In standing, he pronates more on the left side through the midfoot. Ankle dorsiflexion is 5 degrees on each side. 

trigger points in the peroneus longus, gastroc (medial) and soles. 

Weak long toe extensors and short toe flexors; weak toe abductors. 

pathomechanics in the talk crural articulation b/l, superior tip/fib articulation on the right, SI joints b/l

WHAT WE THINK:  

1.    This patient has a leg length discrepancy right sided which is affecting his walking mechanics. He supinates this extremity as can be seen on video, especially at terminal stance/pre swing (ie toe off),  in an attempt to lengthen it; as a result, he has peroneal tendonitis on the right (peroneus is a plantar flexor supinator and dorsiflexor/supinator; see post here). The left medial gastroc is tender most likely due to trying to attenuate the midfoot pronation on the left (as it fires in an attempt to invert the calcaneus and create more supination). see here for gastroc info

2.    Left shoulder:  Frozen shoulder/injury may be playing into this as well as it is altering arm swing.

WHAT WE DID INITIALLY (key in mind, there is ALWAYS MORE we can do):    

•  build intrinsic strength in his foot in attempt to work on getting the first ray down to the ground; EHB, the lift/spread/reach exercises to perform.
• address the leg length discrepancy with a 3 mm sole lift
• address pathomechanics with mobilization and manipulation. 
• improve proprioception: one leg balancing work
• needled the peroneus longus brevis as well as medial gastroc and soles. 
• follow up in 1 week to 10 days.

Pretty straight forward, eh? Look for this pattern in your clients and patients

Pain on the outside of the leg? Could it be your orthotic? What you wear on your feet amplifies the effect of the orthotic.

This woman presented with right-sided pain on the outside of her leg after hiking approximately an hour. She noticed a prominence of the arch in her right orthotic. She hikes in a rigid Asolo boot ( see below). Remember that footwear amplifies the effect of an orthotic!

In the pictures below you can see the prominent arch. The orthotic has her “over corrected” so that she toes off in varus on that side. The rigid footwear makes the problem worse. The peroneus group is working hard (Especially the peroneus longus)  to try and get the first Ray down to the ground.

The “fix” was to soften the arch of the orthotic and grind some material out. Look at the pictures where the pen is pointing to see how some of the midsole material was taken out. Notice how I ground it somewhat medial to further soften the arch.

She felt better much better after this change and is now a “happy hiker” :-)

Thinking on your feet. You have less than 20 minutes with this gentleman, as he has to leave to catch a plane. See how you did. 

Lateral foot pain and cowboy boots?

A 55 YO male patient presents with pain in his left foot area of the cuboid and tail of the fifth metatarsal.  He was told that he had a “locked cuboid” on this side by his chiropractor, who provided some treatment and temporary relief. There has been  no history of trauma and Most recently, he has been wearing cowboy boots and doing “a lot of walking” particularly when he was over in Europe and feels this was a precipitating factor.

Watching him walk in his cowboy boots, the rear foot and heel plate of the cowboy boot is worn into varus. Gait evaluation reveals his left foot to remain in supination (and thus in varus) throughout the entire gait cycle. 

Examination of the foot revealed loss of long axis extension at the metatarsophalangeal and interphalangeal articulations. The cuboid appeared to be moving appropriately. (to see why cuboid function is integral, see this post here. ) There was weakness in the peroneus brevis and peroneus longus musculature with reactive trigger points in the belly of each.  There is tenderness over the tail of the fifth metatarsal and the groove where the peroneal muscle travels through as well as in the peroneal tendon as it travels through here. 

So, what’s up?

This patient has peroneal tendonitis at the point around the foot as it goes around the tail of the fifth metatarsal. Discomfort is dull and achy in this area.  The cowboy boot is putting his foot in some degree of supination (plantar flexion, inversion adduction); this combined with the rear foot varus (from wear on the heel) is creating excessive load on the peroneus longus, which is trying to descend the 1st ray and create a stable medial tripod. Look at the pictures above and check out this post here. 

What did we do?

Temporarily, we created a valgus post on an insole for him.  This will push him onto his 1st metatarsal as he goes through  midstance into termiinal stance. He was asked to discontinue using the boot until we could get the heel resoled with a very slight valgus cant. We also treated with neuromuscular acupuncture over the peroneal group (GB 34, GB 35, GB 36 and a few Ashi points between GB34 and 35) circle the Dragon about the tail of fifth metatarsal, GB41 as well as the insertion of peroneus onto the base of the first metatarsal (approximately SP4).   We K-taped the peroneus longus to facilitate function of peroneus longus.  He was given peroneus longus (plantarflexion and eversion) and peroneus brevis (dorsiflexion and eversion) theraband exercises. 

How did you do? Easy peasy, right? If they were all only this straight forward….

The Gait Guys. teaching you to think on your feet and increasing your gait literacy with each and every post. 

Since the world did not end, you should probably think twice about those motion control shoes….

WE can all agree that there is a time and a place for motion control shoes. For people with chronic ankle sprains or lateral instability (ie, an incompetent lateral compartment; peroneus longus, brevis or tertius), it is neither the time, nor the place.

The lateral ankle is stabilized by both static (ligaments: above lower left) and dynamic (muscles above, lower right) elements. This is often called “the lateral stabilizing complex” The lateral ankle (ie the lateral malleolus) also projects more inferiorly than the medial. This means that when push comes to shove, the ankle is more likely to invert (or go medially) than evert (or go laterally). What protects it? The static component consist of three main ligaments (seen above) the posterior and anterior talofibular ligaments and the calcaneofibular ligaments. The dynamic components are the peroneii muscles. These muscles not only stabilize but also exert an eversion (brings the bottom of the foot to the outside) force on the ankle.

So what you say?

according to one study we found “Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging.”

Hmmm. Remember the midsole? (If not click here and here for a review) Motion control shoes are medially posted. That means they provide more support medially or  have a tendency to tip the foot laterally. SO, motion control shoes shift forces laterally.

A person with chronic ankle instability has weakness of either the static, dynamic, or both components of the lateral stabilizing complex.

bottom line? make sure folks have a competent lateral stabilizing complex and if they don’t, you may want to think twice about using a motion control shoe.

Ivo and Shawn. Increasing your shoe geekiness coefficient on daily basis!                                                                                                                                                      

Foot Ankle Int. 2011 Nov;32(11):1075-80. Increased in-shoe lateral plantar pressures with chronic ankle instability. Schmidt H, Sauer LD, Lee SY, Saliba S, Hertel J. Source

University of Virginia, 2270 Ivy Road, Box 800232, Charlottesville, VA 22903, USA.

Abstract BACKGROUND:

Previous plantar pressure research found increased loads and slower loading response on the lateral aspect of the foot during gait with chronic ankle instability compared to healthy controls. The studies had subjects walking barefoot over a pressure mat and results have not been confirmed with an in-shoe plantar pressure system. Our purpose was to report in-shoe plantar pressure measures for chronic ankle instability subjects compared to healthy controls.

METHODS:

Forty-nine subjects volunteered (25 healthy controls, 24 chronic ankle instability) for this case-control study. Subjects jogged continuously on a treadmill at 2.68 m/s (6.0 mph) while three trials of ten consecutive steps were recorded. Peak pressure, time-to-peak pressure, pressure-time integral, maximum force, time-to-maximum force, and force-time integral were assessed in nine regions of the foot with the Pedar-x in-shoe plantar pressure system (Novel, Munich, Germany).

RESULTS:

Chronic ankle instability subjects demonstrated a slower loading response in the lateral rearfoot indicated by a longer time-to-peak pressure (16.5% +/- 10.1, p = 0.001) and time-to-maximum force (16.8% +/- 11.3, p = 0.001) compared to controls (6.5% +/- 3.7 and 6.6% +/- 5.5, respectively). In the lateral midfoot, ankle instability subjects demonstrated significantly greater maximum force (318.8 N +/- 174.5, p = 0.008) and peak pressure (211.4 kPa +/- 57.7, p = 0.008) compared to controls (191.6 N +/- 74.5 and 161.3 kPa +/- 54.7). Additionally, ankle instability subjects demonstrated significantly higher force-time integral (44.1 N/s +/- 27.3, p = 0.005) and pressure-time integral (35.0 kPa/s +/- 12.0, p = 0.005) compared to controls (23.3 N/s +/- 10.9 and 24.5 kPa/s +/- 9.5). In the lateral forefoot, ankle instability subjects demonstrated significantly greater maximum force (239.9N +/- 81.2, p = 0.004), force-time integral (37.0 N/s +/- 14.9, p = 0.003), and time-to-peak pressure (51.1% +/- 10.9, p = 0.007) compared to controls (170.6 N +/- 49.3, 24.3 N/s +/- 7.2 and 43.8% +/- 4.3).

CONCLUSION:

Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging.

CLINICAL RELEVANCE:

These findings may have implications in the etiology and treatment of chronic ankle instability.

all material copyright 2012 The Homunculus Group/ The Gait Guys. Don’t rip off our stuff. PLEASE ASK 1st!

A Case for “Reverse Engineering”

You have often heard us say: “think of muscle function from a closed kinetic chain perspective”. In other words, the muscle(in the case of gait) working from the foot (or ground) up. Here is a study exemplifying this with the tibialis anterior and peroneus longus.

We remember the tibialis anterior is usually the most prominent muscle on the anterior leg (see 1st 2 pictures above). It has two origins, the lateral tibial condyle and the upper lateral surface of the tibia; it inserts on the medial surface of the 1st (medial) cuneiform and proximal part of base of the first metatarsal of the foot. It is a dorsiflexor and inverter of the foot in open chain (ie before and at heel strike/initial contact), and a dorsi flexor and inverter of the foot (or it brings the tibia medially and everts the foot relative to the tibia) from loading response to midstance. It also helps to maintain the medial longitudinal arch up to this point, and assist in decelerating pronation (along with its antagonist to dorsiflexion, the tibialis posterior). It takes a break at midstance and then contracts again at terminal stance (to counter act its antagonist, the peroneus longus). When running, it remains active through midstance to help pull the leg forward over the foot.

The authors have this to say: “Tibialis anterior restrained rearfoot plantarflexion from heel contact to 10% stance, and eversion between 10% stance and footflat.”

No surprises here.

Now the peroneus longus: “Activity in peroneus longus was consistent with its role in causing eversion after heel contact, then as a stabiliser of the forefoot after heel rise. ”

The peroneus (or fibularis) longus arises from the head and upper two-thirds of the lateral surface of the fibula, from the deep surface of the fascia, and from the intermuscular septa between it and the muscles on the front and back of the leg; occasionally also by a few fibers from the lateral condyle of the tibia.  You can see from it attachments that it can influence the entire upper lateral leg.

It’s tendon runs down the fibular shaft, wraps around the lateral malleolus, travels obliquely under the foot, crossing the lateral cubiod (which it everts after midstance to help with supination) crosses the sole of the foot obliquely, and inserts into the lateral side of the base of the first metatarsal and lateral aspect of the 1st cunieform.  

It acts from just prior to heel strike to limit excessive rearfoot inversion, through midstance to decelerate subtalar pronation and assists in stabilization of the midfoot articulations, and into terminal stance and pre swing to lock the lateral column of the foot for toe off and plantar flex the 1st ray (creating a good foot tripod), allowing dorsal posterior shift of the 1st metatarsal-phalangeal joint axis (necessary for dorsiflexion of the hallux (big toe)).

The peroneus brevis arises from the lower two-thirds of the lateral surface of the shaft of the fibua and from the intermuscular septa separating it from the adjacent muscles on the front and back of the leg. Again. lots of influence here.

It travels behind the lateral malleolus (and in front of the peroneus longus) and inserts into the tuberosity at the base of the fifth metatarsal.

It acts in a similar timeframe as the longus, copressing the tarsals to provide midfoot stabilization, and a significant eversion moment of the foot (helping to push you on to the base of the 1st metatarsal).

You can see how the peroneii could work together also to produce a small plantar flexion moment of the ankle and lateral movement of the lower leg. Because of their route around the lateral malleolus, they also can internally rotate the tibia (from a closed chain perspective; remember the tibia SHOULD be extenally rotation at this this point) so it can act to dampen or attenuate supination. This is also supported by the study:

“Activity in peroneus brevis suggested a role in restraining lateral rotation of the leg over the foot, late in stance.”

We are definitely the Uber Gait Nerds of the internet. We are bending your mind around the foot (rather than the foot around your mind).

Ivo and Shawn

Abstract

This study examined stance phase foot kinematics, kinetics and electromyographic (EMG) activity of extrinsic muscles of 18 healthy males. Three-dimensional kinematic and kinetic data were obtained via video analysis of surface markers and a force plate. Ankle joint moments are described about orthogonal axes in a segmental coordinate system. Kinematic data comprise rearfoot and forefoot motion, described about axes of a joint coordinate system, and medial longitudinal arch height. Surface EMG was obtained for tibialis anterior, soleus, gastocnemius medialis and lateralis, peroneus longus and peroneus brevis and extensor digitorum longus. It was concluded that the demands on the controlling muscles are greatest prior to foot flat and after heel rise. Tibialis anterior restrained rearfoot plantarflexion from heel contact to 10% stance, and eversion between 10% stance and footflat. Activity in peroneus longus was consistent with its role in causing eversion after heel contact, then as a stabiliser of the forefoot after heel rise. Activity in peroneus brevis suggested a role in restraining lateral rotation of the leg over the foot, late in stance.

http://www.ncbi.nlm.nih.gov/pubmed/11206820

Foot Ankle Int. 2001 Jan;22(1):31-41.

Extrinsic muscle activity, foot motion and ankle joint moments during the stance phase of walking.

Hunt AE, Smith RM, Torode M.

School of Physiotherapy, Faculty of Health Sciences, Lidcombe, NSW, Australia. a.hunt@cchs.usyd.edu.au

Erratum in

• Foot Ankle Int 2001 Jul;22(7):543.