Shin splints

A shin splint, also known as medial tibial stress syndrome, is pain along the inside edge of the shinbone (tibia) due to inflammation of tissue in the area.<ref name=OI2019>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Generally this is between the middle of the lower leg and the ankle.<ref name=Res2012/> The pain may be dull or sharp, and is generally brought on by high-impact exercise that overloads the tibia.<ref name=OI2019/> It generally resolves during periods of rest.<ref name=Stat2019/> Complications may include stress fractures.<ref name=Res2012/>

Shin splints typically occur due to excessive physical activity.<ref name=OI2019/> Groups that are commonly affected include runners, dancers, gymnasts, and military personnel.<ref name=Res2012>Template:Cite journal</ref><ref>Template:Cite journal</ref> The underlying mechanism is not entirely clear.<ref name=Res2012/> Diagnosis is generally based on the symptoms, with medical imaging done to rule out other possible causes.<ref name=Res2012/>

Shin splints are generally treated by rest followed by a gradual return to exercise over a period of weeks.<ref name=OI2019/><ref name=Res2012/><ref name=Stat2019/> Other measures such as nonsteroidal anti-inflammatory drugs (NSAIDs), cold packs, physical therapy, and compression may be used.<ref name=OI2019/><ref name=Res2012/> Shoe insoles may help some people.<ref name=OI2019/> Surgery is rarely required, but may be done if other measures are not effective.<ref name=Res2012/> Rates of shin splints in at-risk groups range from 4% to 35%.<ref name=Res2012/> The condition occurs more often in women.<ref name=Res2012/> It was first described in 1958.<ref name=Res2012/>

Signs and symptoms

Shin splint pain is described as a recurring dull ache, sometimes becoming an intense pain, along the inner part of the lower two-thirds of the tibia.<ref>Template:Cite journal</ref> The pain increases during exercise, and some individuals experience swelling in the pain area.<ref>Template:Cite journal</ref> In contrast, stress fracture pain is localized to the fracture site.<ref>Template:Cite journal</ref>

Women are several times more likely to progress to stress fractures from shin splints.<ref name= "YatesWhiteWhite2004"/><ref name="BennettPluemer2001">Template:Cite journal</ref><ref>Template:Cite journal</ref> This is due in part to women having a higher incidence of diminished bone density and osteoporosis.<ref>Healthwise Staff. (7 December 2020). Low bone density. University of Michigan Health. Retrieved 26 June 2021, from https://www.uofmhealth.org/health-library/tp23004spec</ref>Template:Cn

Causes

Shin splints typically occur due to excessive physical activity.<ref name=OI2019/> Groups that are commonly affected include runners, dancers, and military personnel.<ref name=Res2012/>

Risk factors for developing shin splints include:

• Flat feet or rigid arches<ref name=OI2019/>
• Being overweight<ref name=Stat2019>Template:Cite journal</ref>
• Excessively tight calf muscles (which can cause excessive pronation)<ref>Template:Cite journal</ref>
• Engaging the anti-pronatory (supinating) muscles in excessive amounts of eccentric muscle activity<ref name= "YatesWhiteWhite2004">Template:Cite journal</ref>
• Undertaking high-impact exercises on hard, non-compliant surfaces (such as running on asphalt or concrete)<ref name= "YatesWhiteWhite2004"/>

People who have previously had shin splints are more likely to have them again.<ref name=Moen2009/>

Pathophysiology

While the exact mechanism is unknown, shin splints can be attributed to the overloading of the lower leg due to biomechanical irregularities resulting in an increase in stress exerted on the tibia. A sudden increase in intensity or frequency in activity level fatigues muscles too quickly to help shock absorption properly, forcing the tibia to absorb most of the impact. Lack of cushioning footwear, especially on hard surfaces, does not absorb transmitting forces while running or jumping.<ref name="De Permentier">Template:Cite journal</ref> This stress is associated with the onset of shin splints.<ref name="Craig, D. I. 2008">Template:Cite journal</ref> Muscle imbalance, including weak core muscles, inflexibility and tightness of lower leg muscles, including the gastrocnemius, soleus, and plantar muscles (commonly the flexor digitorum longus) can increase the possibility of shin splints.<ref name=Galbraith>Template:Cite journal</ref> The pain associated with shin splints is caused from a disruption of Sharpey's fibres that connect the medial soleus fascia through the periosteum of the tibia where it inserts into the bone.<ref name="Craig, D. I. 2008" /> With repetitive stress, the impact forces eccentrically fatigue the soleus and create repeated tibial bending or bowing, contributing to shin splints. The impact is made worse by running uphill, downhill, on uneven terrain, or on hard surfaces. Improper footwear, including worn-out shoes, can also contribute to shin splints.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="webmd.com">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Diagnosis

File:Shinsplint-mri.jpg

Magnetic resonance image of the lower leg in the coronal plane showing high signal (bright) areas around the tibia as signs of shin splints.

Shin splints are generally diagnosed from a history and physical examination.<ref name=Stat2019/> The important factors on history are the location of pain, what triggers the pain, and the absence of cramping or numbness.<ref name=Stat2019/>

On physical examination, gentle pressure over the tibia will recreate the type of pain experienced.<ref name=Moen2009/><ref name=AFP2011>Template:Cite journal</ref> Generally more than a 5 cm length of tibia is involved.<ref name=Moen2009>Template:Cite journal</ref> Swelling, redness, or poor pulses in addition to the symptoms of shin splints indicate a different underlying cause.<ref name=Stat2019/>

Differential diagnosis

Other potential causes include stress fractures, compartment syndrome, nerve entrapment, and popliteal artery entrapment syndrome.<ref name=AFP2011/> If the cause is unclear, medical imaging such as a bone scan or magnetic resonance imaging (MRI) may be performed.<ref name=Stat2019/> Bone scans and MRI can differentiate between stress fractures and shin splints.<ref name=Moen2009 />

Treatment

It is important to reduce significantly any pain or swelling before returning to activity.

Treatments include rest, ice, and gradually returning to activity.<ref name=Galbraith /> Rest and ice help the tibia to recover from sudden, high levels of stress and reduce inflammation and pain levels.

Strengthening exercises should be performed after pain has subsided, on calves, quadriceps and gluteals.<ref name=Galbraith /> Cross training (e.g., cycling, swimming, boxing) is recommended in order to maintain aerobic fitness.<ref>Template:Cite journal</ref>

Individuals should return to activity gradually, beginning with a short and low intensity level. Over multiple weeks, they can slowly work up to normal activity level. It is important to decrease activity level if any pain returns. Individuals should consider running on other surfaces besides asphalt, such as grass, to decrease the amount of force the lower leg must absorb.<ref name="YatesWhiteWhite2004" />

Orthoses and insoles help to offset biomechanical irregularities, like pronation, and help to support the arch of the foot.<ref>Template:Cite journal</ref>

Other conservative interventions include improving form during exercise, footwear refitting, orthotics, manual therapy, balance training (e.g., using a balance board), cortisone injections, and calcium and vitamin D supplementation.<ref name=Galbraith />

Deep tissue massage is one of the massage techniques that may be useful. A technique such as deep transverse friction to relieve muscle tightness will help stop the build-up of scar tissue. This can overall release tension in the calf muscle area, relieving pressure that is causing pain.<ref name="De Permentier"/>

Less-common forms of treatment for more-severe cases of shin splints include extracorporeal shockwave therapy (ESWT) and surgery.<ref>Template:Cite journal</ref> Surgery does not guarantee 100% recovery, and is only performed in extreme cases where non-surgical options have been tried for at least a year.<ref>Template:Cite journal</ref>

Epidemiology

Rates of shin splints in at-risk groups are 4% to 35%.<ref name=Res2012/> Women are affected more often than men.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>