Barefoot Biomechanics

Understanding (Subtle) Peroneal Subluxation: Treating the Cause vs. Symptoms

Welcome to another post in the Barefoot Strong Blog!   Today’s post is a great example of why all health and wellness professionals (including those that are specialists) must always consider the greater picture and consider integrated movement systems.

Although I am a Podiatrist and am presented with patients complaining of foot & ankle pain or dysfunction, I take great pride in approaching all my patients with a holistic and functional approach.   Each patient I see is assessed for foot function as it relates to the entire body and integrated movements such as walking, squatting and landing.

Below is is a summary and explanation for an often misdiagnosed cause of lateral foot pain in runners.  

Female Runner with Chronic Lateral Ankle Pain

I was recently referred a patient with chronic lateral ankle pain which was not responding to current conservative treatment and physical therapy (which is always a signal that we need to delve deeper into the actual cause vs. symptoms).

Patient is a 29 yo female, avid runner who was training for a marathon last year when she began to experience lateral ankle pain.   Pain is greatest during push-off and is described as dull and aching.   Patient reports no history of ankle sprains or ankle instability.   No acute injury associated with this pain.

ankle_peroneal_tendinitis_symptoms01

Patient has seen several doctors including two Podiatrists and one Orthopedists, all of which diagnosed perineal tendonitis and the recent diagnosis of subluxing peroneals.   In the past year the patient has done several courses of physical therapy consisting of ankle mobility and strengthening.  In addition she has tried orthotics and two steroid injections to the peroneal tendons which provided mild relief however the pain eventually returned.

Patient recently had a diagnostic ultrasound done which demonstrated “subtle subluxing peroneals”.  The radiologist reported being able to reproduce the subluxation when plantarflexing and everted the foot.  The Podiatrist who ordered the US recommended surgery to correct the peroneal subluxation.

The patient seeks a second opinion as she believes surgery is extreme for her foot pain.

Patient Examination

On examination a few things that stood out included:

  • Pain on palpation along peroneal tendons posterior fibula right foot
  • Mild pain on resisted eversion
  • Limited ankle mobility right foot < 5 degrees
  • On stance mild calcaneal eversion noted 5 degrees
  • Gait assessment demonstrated increased eversion on late midstance, low gear push-off and tibial femoral external rotation (TFER)

Screen Shot 2014-09-15 at 11.42.38 AM                Screen Shot 2014-09-15 at 11.42.58 AM

TFER right foot            Abducted right foot in mid stance

Screen Shot 2014-09-15 at 11.43.20 AM             Screen Shot 2014-09-15 at 11.43.39 AM            Screen Shot 2014-09-15 at 11.43.52 AM

Abducted right foot           STJ eversion and knee valgus

A Closer Look at Lateral Ankle Anatomy

When considering lateral ankle pain and possible peroneal subluxation a detailed understanding of lateral anatomy is of course important.  The lateral compartment of the lower leg is comprised of the peroneus longus and brevis muscles.  Distally, they both travel posterior to the fibula within the fibular groove.   At this level both tendons are in the same fascial sheath with the peroneus brevis anteromedial to the peroneus longus.  Below the fibula, the peroneus longus and brevis muscles form separate sheaths to prepare for the longus turn under the cuboid towards its medial foot insertion.

Inferiorly, the peroneal tendons are bound by the calcaneofibular ligament (CFL) and the inferior peroneal retinaculum.   While superiorly they are bound by the superior peroneal retinaculum.

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The pathoanatomy of peroneal subluxation lies within the integrity of the superior peroneal retinaculum, its contents and the ability to maintain those contents within the retromalleolar groove.

The superior peroneal retinaculum has a lateral, non-osseous roof and a floor comprised of an osseous retromalleolar groove and medial non-osseous posterior intermuscular septum of the leg portions.

Understanding Peroneal Subluxation / Dislocation

Often considered an issue related to the fibular groove, the pathomechanics of peroneal subluxation and dislocation is in fact not related to the fibular groove but rather to fibular position and rotation.

When the fibular is externally rotated (as in the case of pronation and TFER) it causes a relaxation of the superior peroneal retinaculum and allows the peroneal tendons to roll on each other and possibly sublux over the lateral malleolus.   In an acute setting the mechanism of injury is commonly a dorsiflexed foot and sudden or heavy contraction of the peroneal muscles on an everted subtalar joint and externally rotated fibula.

Acute symptoms of snapping or popping with pain and feelings of instability are common with a true peroneal dislocation or subluxation, and often times the peroneal tendons can be seen snapping over the fibula.

Subtle Peroneal Subluxation

When we consider subtle peroneal subluxation the pathomechanics are similar to that of an acute or true peroneal dislocation, however to a lesser degree.   The same mechanism of plantarflexion and on everted STJ and externally rotated fibula is present but instead of snapping over the fibula, the tendons roll on each other causing irritation to the tendons and surrounding tendon sheaths.

In the case of my patient complaining of lateral ankle pain, understanding her functional movement is important in determining the true cause of her symptoms.  Isolated examination revealed localized pain along the peroneal tendons posterior to the lateral malleolus and the US confirmed subtle subluxation reproducible during plantarflexion and eversion of the foot.

Knowing my patient’s diagnosis, pathomechanics of this diagnosis and having assessed her gait it became quite apparent that the driving force behind her pain was the tibial femoral external rotation present during her gait cycle.

Understanding TFER

I was first introduced to the concept of TFER in Shirley Sahrmann’s book Movement System Impairment Syndromes of the Extremities.   Sahrmann describes TFER as an external rotation of the tibia / fibula relative to the femur.

This external rotation is often associated with overactive:

– gastrocnemius (lateral head)

– bicep femoris (short head)

– TFL/ITB

Screen Shot 2014-09-15 at 11.42.58 AM

Note the left foot external rotation at swing phase

Most often observed during the propulsive phase of gait this TFER impacts alignment during midstance (causing knee valgus) and propulsion (abducted push-off on an everted foot).   This push-off in an abducted and everted foot is the movement that reproduces subluxation of the peroneals.

Correcting the Cause

When treating TFER always start with mobilization or inhibition of the overactive muscles.   If knee valgus is present with the TFER then much focus should be on the TFL/ITB.

Step 1 – SMR or trigger point release gastroc, BF and TFL everyday for at least 5 – 10 minutes

Step 2- Dynamic mobilization / stretches to gastroc, BF and TFL

Step 3- Lock it in with strengthening medial or internal tibial / femoral rotation with pigeon-toed hamstring curls as well as hip external rotators with reverse clam shells

Further Considerations

I hope that this case presentation leads to a deeper appreciation for the importance of looking at functional movements and integrated systems when assessing patients with localized pain.

I’ve been seeing a large number of patients with over-pronation syndrome presenting with lateral ankle pain and subsequently finding out through MRI that they have peroneal tears.   I believe that the driving force behind these peroneal tears in the over-pronated foot are due to overlooked subtle peroneal subluxation secondary to TFER and pushing off (plantar flexing) on an everted STJ.

I am doing a small study to further evaluate this concept and appreciate any feedback and interest in this topic that you may have!

Dr Emily Splichal

To learn more about TFER, performing gait assessment and rehab programming similar to this, please visit http://www.ebfafitness.com

Are you barefoot strong?  

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