Some biomechanical aspects of the foot and ankle in athletes with and without shin splints Jukka T. Viitasalo, PhD and Martti Kvist, MD

 

Taylor Dourney, Caroline Kolada, Kathleen McAuliffe, Kristin Pawlak, Kirby van Erkel  

The leg is composed of five distinct regions Upper leg Knee Lower leg Ankle Foot

 

The Lower Extremity

Medial Tibial Stress Syndrome (MTSS)

“Shin splints”

Pain in the anterior part of the lower leg after repetitive overuse

Most common in athletes, specifically runners  

Why should we care?

Shin splints account for nearly 60% of all overuse injuries of the leg

About 10-20% of runners will experience shin splints at least once during their career

 

Why do shin splints occur?

Etiology of most overuse injuries is multifaceted

Three categories for cause of pain

Bone origin

Vascular origin

Soft tissue origin

Major Etiological Factors

Training methods

Training surfaces

Muscle dysfunction and inflexibility

Shoe design

The biomechanics of running

Biomechanics of Shin Splints

Subtalar joint’s triphase motion

Excess and abnormal pronation

Amount and timing of movement

Purpose of the Study

Comparisons between athletes with and

without shin splints

Mobility of subtalar joint

Position of lower leg and heel

Angular displacements of lower

leg and heel

Biomechanics of Running

Swing phase

Stance phase

Subtalar Joint

Inversion/Supination

Rigid support

Initial contact

Terminal stance

Eversion/Pronation

Shock absorption

Loading response Midstance

Abnormal Mobility of Subtalar Joint

Overpronation

Flat feet, uneven surfaces, repetitive jumping

Results of the Study

Increased eversion and inversion → shin splints

Are some people at a higher risk for MTSS?

After studying many risk factors, only Body Mass Index (BMI) showed a significant correlation to developing shin splints

Higher BMI = higher risk of shin splints

(Plisky et. al, 2007)

Does sex matter?

Multiple studies show females more likely to acquire MTSS than males

Women are 1.5 to 3.5 times more likely to develop under same conditions and have MTSS worsen to stress fractures

In part due to lower bone density and increased chances of osteoporosis in women

The Evolution of Shin Splints

Chimpanzees do not experience, but likely that some hominins did. Unique to bipedal humans

Humans have arch in foot, supported by the plantar fascia

With larger arch, risk for lower leg injuries like shin splints increases

arch

Is it really shin splints? Often a primary general diagnosis, specific diagnosis difficult

Normally diagnosed by physician palpation of medial, distal shin

If chronic, extra tests required to rule out more severe conditions  MTSS

General Diagnosis

If chronic...

Severe MTSS

X-Ray/bone scan

Neurological Exam

MRI

Is prevention possible?

Since experts do not agree upon cause of MTSS, it makes prevention very difficult

Focus is on controlling proposed risk factors

Controlling all risk factors in all athletes is impossible

Promising Ways to Control Risk Factors Replace running shoes every 300-600 miles

Graduated running programs

Shock-absorbent & pronation controlled insoles

Orthotic Supports Stabilizes subtalar joint (pronation-control)

Shock-absorbing insoles

Redistributes pressure on the bottom of the foot

Custom or over-the-counter

Athletic training clinicians should... Increase strength & endurance of soleus

Control over pronation

Promote adequate shock absorption & maintenance of proper foot biomechanics

Work with coaches to commit 1 day a week to cross-training to relieve stress

Sources http://ajs.sagepub.com/content/11/3/125.full.pdf+html http://dubinchiro.com/2013/10/shin-splints/ http://dubinchiro.com/2013/10/achilles-tendinopathies-in-runners-causes-treatment-and-prevention/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2386425/pdf/attr-43-03-316.pdf

Aydog S, Tetik O, Demirel H, Doral M. Differences in sole arch indices in various sports. British Journal

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Latimer, B. The perils of being bipedal. Annals of Biomedical Engineering, 33 (2005), pp. 3–6

Plisky MS, Rauh MJ, Heiderscheit B, Underwood FB, Tank RT. Medial tibial stress syndrome in high school cross-country runners: incidence and risk factors. J Orthop Sports Phys Ther. 2007;37(2): 40–47. Yates, B., White, S. (2004). The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. American Journal of Sports Medicine, 32(3), 772–780.