shin splints

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Shin splints
Classification and external resources
Anatomy of the shin.
ICD-9	844.9

Shin splints is a general term used to refer to a painful condition in the shins.^[1] It is often caused by running or jumping, and may be very slow to heal. A formal medical term for the condition is medial tibial stress syndrome.^[2][3]

Two specific conditions

Overused muscle

One cause is an overused muscle, either as an acute injury or delayed onset muscle soreness (DOMS). The muscle pain is caused by any activity that involves running, jumping, also sometimes even walking. Untreated shin splints can lead to a stress reaction mid-shaft in the tibia, which can eventually lead to a stress fracture. A stress fracture can be diagnosed by a bone scan or an MRI and takes much longer to heal than shin splints.

Chronic compartment syndrome

A problem that can mimic anterior shin splints is chronic compartment syndrome (CCS). This is a serious problem that can lead to significant loss of function in the lower leg. CCS occurs when swelling within the indistensible anterior compartment of the leg reduces blood flow. This relative lack of blood, ischemia, can cause more swelling and generate a positive feedback loop. In severe cases the result can be acute compartment syndrome (ACS) which requires emergency surgery to prevent ischemic muscle necrosis due to lack of blood.

Diagnosis

CCS may be the problem if pain worsens steadily during exercise rather than improving as the ligaments and muscles warm.Symptoms of shin splints: Tingling in the foot is a particular red flag; it indicates compression of the nerve.

If a bone problem is suspected to be causing inflammation of connective tissue, a bone scan can be useful in confirming the diagnosis. Also, in some minor cases, the best thing for shin splints is just plain rest in the legs. It may take weeks or months of healing depending on different cases of shin splints.

Magnetic resonance imaging has been proposed as a diagnostic technique.

Causes

Most of these causes are contraindicated by the MayoClinic's website;^[1] however, the purpose of the muscles of the anterior shin (tibialis anterior) is to dorsiflex the foot (bend the foot upwards at the ankle). Other muscles here include the extensor digitorum longus muscle and the extensor hallucis longus, which move the toes, 2-5 and the big toe respectively, upwards. It may not be obvious why a muscle which raises the toe can be stressed or injured by running, given that it is not responsible for propulsion. The reason is that some runners overstride, and land heavily on the heel with each footstrike (thus, shin splints are a common ailment in military boot camp^[4], where trainees march extensively by extending the leg forward and forcefully striking the boot heel on the ground). When this happens, the forefoot rapidly slaps down to the ground. Effectively, the foot, which is dorsiflexed prior to making contact with the ground, is forcefully plantarflexed. This forceful plantar flexion of the foot causes a corresponding rapid stretch in the attached muscles. A reflex in the muscles responds, causing a powerful contraction. It is this eccentric contraction which leads to muscle soreness and possible injury to the muscle, tendon or connective tissue.^{[citation needed]}

It is also believed by NATA athletic trainers that a contributing cause of shin muscle pain in some cases is the relative weakness of the muscles on the anterior of the lower leg compared to those in the calf. Exercises designed to strengthen the muscles of the shin are prescribed to even out the muscle imbalance. Over time, usually at least 10 days, the pain in the shins is slowly alleviated as the muscle imbalance is corrected. The shin pain is attributed to a forced extension of the muscle, in this case by the opposing calf muscles which "overpower" the shin muscles.

Treatment and prognosis

Acute treatment

The immediate treatment for shin splints is rest. Running and other strenuous lower limb activities, like basketball and other sports which include flexing the muscle, should be avoided until the pain subsides and is no longer elicited by activity. In conjunction with rest, anti-inflammatory treatments such as icing and drugs, such as non-steroidal anti-inflammatory drugs (in particular, NSAID gel) may be suggested by a doctor or athletic trainer. Over-the-counter pain relievers can also be taken, though there is some controversy over their effectiveness. Furthermore, the lower legs may be taped to stabilize and take some load off the periosteum. Finally, using good shoes (ideally compensating for individual foot differences) is important. The shin can be trained for greater static and dynamic flexibility through adaptation, which will diminish the contracting reflex, and allow the muscles to handle the rapid stretch. The key to this is to stretch the shins regularly. However, static stretching might not be enough. To adapt a muscle to rapid, eccentric contraction, it has to acquire greater dynamic flexibility as well. One way to work on the dynamic flexibility of the anterior shin is to subject it to exaggerated stress, in a controlled way, such as walking on the heels. If the muscle is regularly subject to an even greater dynamic, eccentric contraction than during the intended exercise, it will become more capable of handling the ordinary amount of stress. Experienced long-distance runners practice controlled downhill running as a part of training, which places greater eccentric loads on the quadriceps as well as on the shins. A physical therapist, athletic trainer, or doctor should be consulted before engaging in this type of training.

Long-term treatment

The long-term remedy for muscle-related pain in the shin is a change in the running style to eliminate the overstriding and heavy heel strike.^{[citation needed]}

Sprinting is performed on the toes, as is some middle-distance running. In most middle to long-distance running, striking with the heel, rolling through the foot and pushing off the ball is the most efficient. Competitive runners vary in styles, but as distance increases, more runners tend towards striking with the heel or mid-foot as the natural gait of the body - most marathoners can be seen to strike with the heel.^[5] Striking solely with the forefoot over distance focuses stress on the calves and underuses the hamstrings. Moreover in preventing shin-splints, heel-striking offers the best shock absorption and natural form, reducing impact stress on the calf and shin muscles.^[6]

In both postures, the center of gravity is directly over the foot. Physics requires this, because it is the condition that prevents a body from falling over. An object falls over when its centre of gravity shifts too far one way or the other outside of the range of its supporting base. Arching the back shifts the body's centre of gravity towards the rear, so that the legs must tilt forwards to compensate; shifting the weight towards the ball of the foot, and to the toes. Bending forwards at the waist has the opposite effect: the legs tilt backwards at the ankle, shifting the weight towards the heels.

During running, the centre of gravity changes dynamically. Because for most of the running cycle a drive leg extends backwards, the torso appears to tilt forwards to compensate for this. This forward tilt is similar to what happens in a standing position when one leg is raised from the ground and extended backwards. Inexperienced runners observe this forward tilt in professional athletes and attempt to imitate it by bending at the waist, which isn't the same thing. In the forwards tilt, the torso and extended leg still form a straight line; or even a slight backwards curve. Further irritation can lead to muscle separating, or detaching, from the bone.

The shin muscles can also be somewhat alleviated by footwear and choice of surface. Runners who strike heavily with the heel should look for shoes which provide ample rear foot cushioning. Such shoes may be referred to as "stability" or "motion control" shoes. The so-called "neutral" shoes for bio-mechanically efficient runners may not have adequate support in the heel, because the runners for whom these shoes are intended do not require it. When their cushioning capability degrades, the shoes should be replaced. The commonly recommended replacement interval for shoes is 300-400 miles (480-640 kilometres).^[7] Excessive pronation can be reduced by extra supports under the arch. Running shoes which have a significant supporting bump under the arch are called "motion control" shoes, because they work by limiting the pronating motion. Also shoes with cushion shock features and shoe inserts can help prevent future problems.

Runners who race over rough terrain such as cross-country runners tend to tape just above the ankle and just below the knee with sports tape to prevent movement of bones, primarily the shin to prevent painful shin splints. This is also done to reinforce weak ankles and reduce the chance of sprains and other injuries.

In one study, use of an orthosis did not measurably improve recovery.^[8] term "shin splints" refers to pain and tenderness along or just behind the inner edge of the tibia, the large bone in the lower leg. Shin splints—or medial tibial stress syndrome as it is called by orthopaedists—usually develops after physical activity, such as vigorous exercise or sports. Repetitive activity leads to inflammation of the muscles, tendons, and periosteum (thin layer of tissue covering a bone) of the tibia, causing pain. The bone tissue itself is also involved.

Notes and references

1. ^ ^{a b} "Shin splints - MayoClinic.com". http://www.mayoclinic.com/health/shin-splints/DS00271. Retrieved on 2007-12-23. 
2. ^ Abramowitz AJ, Schepsis A, McArthur C. The medial shin splither underlying conditions.. 
3. ^ Ashford R (1999). "Trauma related shin splints. Shin splints are symptoms, not a diagnosis". BMJ 318 (7197): 1560. PMID 10356037. http://bmj.com/cgi/pmidlookup?view=long&pmid=10356037. 
4. ^ http://www.militarytimes.com/forum/showthread.php?t=1564985
5. ^ The Art of Running: With the Alexander Technique by Malcolm Balk and Andrew Shields (Ashgrove Publishing, 2000)
6. ^ Foot Strike running jogging
7. ^ http://running.about.com/od/shoesapparelandgear/f/replaceshoes.htm
8. ^ Johnston E, Flynn T, Bean M, et al. (2006). "A randomized controlled trial of a leg orthosis versus traditional treatment for soldiers with shin splints: a pilot study". Mil Med 171 (1): 40–4. PMID 16532872. 

External links

• Treating and Preventing Shin Splints (watfxc.com)
• Shin Splints: Clinical Classification
• How To Tape Shin Splints