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Introduction

An overuse injury is one that results from active participation in athletic activities for which the body is unable or unprepared to handle. One of the most common overuse injuries in sports, especially with runners, is known as "shin splint syndrome"-a generic term referring to a syndrome in which stress over time has caused injury to the lower leg. It is responsible for 18% of all overuse injuries and represents 4 to 13% of running injuries [1, 2]. Shin splints frequently occur in individuals who have recently begun running or who have increased their running regimen. Other athletes commonly afflicted with this injury include figure skaters and gymnasts.

Types of Shin Splints

Symptoms are generally localized in two main areas of the lower half of the leg-either along the front (anterior) or back (posterior). Although both anterior and posterior shin splints present differently, the treatment and causative factors are relatively the same.

Anterior shin splint syndrome, when the pain is felt along the front aspect of the lower leg, is most commonly seen in those who have just started a running program. Posterior shin splint syndrome, when the pain is found on the inside back part of the lower leg, is usually seen in runners who are over-training or in those with biomechanical imbalances (e.g., excessive collapse of the foot arch known as over-pronation).

Signs and Symptoms

Initially, shin splint symptoms present with vigorous activity and may linger even after finishing. The type of pain often associated with shin splints can be described as a deep ache in the bone and may be burning in nature. In other cases, the pain may feel like sharp needles in the lower leg that shoot toward the ankle. Usually the pain is relieved with rest. If not adequately treated, the onset of pain can occur earlier in the activity and relief may take longer. In severe cases, pain may be present at rest without any activity to aggravate it.

What causes Shin Splints?

Shin splints do not occur overnight; it gradually develops over time due to the repeated stress on tendons and their attachments to bone. Left untreated, shin splints can result in several distressing, yet avoidable, complications. Simple stretching, proper shoegear selection and adjuncts, such as insoles, play vital roles in prevention and treatment of shin splints.

The underlying problem responsible for shin splint development is abnormal biomechanics (i.e., improper functioning of the involved anatomy). The anterior and posterior leg muscle groups should be equal in strength. When one group overpowers the other, the weaker muscle must work harder to balance the muscle pulls.

Lack of proper stretching before and after running can increase susceptibility to shin splints. Tight calf muscles limit motion at the ankle joint, which in turn places additional stress on the tendon attachments resulting in shin splints. Frequent and sudden stopping while running and regular down hill running can contribute to shin splints. Although primarily associated with posterior shin splints, flat foot syndrome (over-pronation) can also present with anterior shin splint symptoms. Improper fitting shoes can create artificial environments in which extra strain is placed on tendons. Excessive wear or breakdown on the medial (arch) side of the shoe, usually resulting from unbalanced tendon function, behaves like a collapsed arch (flat foot). Excessive compression of the shoe heel causes the calf muscles to work more to compensate for a lack of heel stability. Bottom line: Any activity that results in abnormal strain on a tendon’s attachment to underlying bone can cause symptoms of shin splint syndrome.

Treatment Options and Preventative Measures

Shin splints can be prevented. The measures described below are designed to prepare the body for the abnormal stresses associated with vigorous activity.

Warm-Up: All active athletes, regardless of level and type of exercise, should take a few extra minutes to properly warm-up and stretch. Warming-up greatly decreases the chance of straining tendons [2, 4]. The proper way to start exercising is to move the body around to increase blood flow. Move each body part through its entire range of motion that will be required in the exercise for which you are preparing.

Stretching: Once warmed-up, stretching should be initiated. Stretch lightly and hold each stretch for up to 20 seconds without bouncing. To strengthen the area after warming-up, walk around on your heels with yours toes in the air. Without stretching and use, tendons tend to contract and shorten—this increases stress to various parts of the musculoskeletal system—stress we want to avoid. Stretching and warm-downs after activity allow the muscles to eliminate waste products and limit the amount of muscle ache after strenuous exercise.

Proper Shoegear: Runners have a distinct advantage over figure skaters and gymnasts—runners have complete control over their shoegear and can select particular features that will address the mechanism responsible for their shin splints.

Most shoes have a mileage lifespan of 300-350 miles. Many runners will complain of leg cramps, ankle pain, and knee pain when exceeding the recommended shoe mileage. One simple way to test shoe laxity is to grab the shoe in the front and back while twisting in opposite directions. If the arch area twists easily, then stability has been compromised. Compare twisting an old shoe with a new one to gauge the flexibility differences. Note: This twist test only works for running and walking shoes; the additional rigid materials in cross-training and basketball shoes prohibit the twist test from accurately assessing shoe stability.

Orthoses (Shoe Inserts): Orthoses are devices placed in shoes to control abnormal motion. Over-the-counter (OTC) orthoses will physically hold the arch up, thereby relieving some of the troubled tendons’ work. The support of the orthoses should not be felt in the middle of the arch, but should be located closer to the heel. A slow break-in period is recommended when initiating orthoses. The orthoses should be worn as long as tolerable initially (usually 2-3 hours). When they become uncomfortable, remove them. With each successive day, increase the amount of time the devices are worn. Ideally, the orthoses should feel comfortable by the end of two weeks to the point where they can be tolerated for the entire day.

If OTC orthoses offer only mild relief, custom-molded orthoses may be more beneficial. Your foot specialist can prescribe custom-molded orthoses that conform to each foot’s unique shape. These prescribed devices can last upwards of five years, but customizing comes with a price—a $300-400 price tag to be more specific. At about $20-40 a pair, OTC orthoses are a viable option offering varying degrees of success. OTC devices are less durable, need to be replaced more frequently, and because they were designed to fit a population of feet rather than your own, may not fit properly to provide optimal performance. Like shoegear, the symptoms and progression of relief will dictate when the devices need to be replaced.

Note for track runners: Running on tracks with turns can place stress repeatedly on the side of the turns—a simple remedy is to alternate directions around the track from one training session to the next.

Conservative Options

Conservative treatments are primarily designed to decrease the inflammatory process associated with the pain of shin splints and reduce the excessive stress placed on tendon and bone. These options should be used in conjunction with the preventative measures just described.

Heat/Ice: Heat increases muscle blood flow prior to exercise and ice decreases post-exercise inflammation.

Anti-inflammatory Medications: Non-steroidal anti-inflammatory medications (NSAIDs) like Ibuprofen can enhance the body’s recovery from acute inflammatory reactions, especially when combined with rest. Physicians should be consulted on the proper medications.

Other: Other physician-mediated treatment plans include corticosteroid and ultrasound therapy to decrease the inflammatory process.

Surgery

Surgery for shin splints should be considered after exhausting all conservative options. Reconstructive flat foot surgery and tendon lengthening procedures to relieve undo stress are some surgical options available. Post-operative recovery involves cast immobilization and physical rehabilitation for strengthening. Ultimately, you will need to determine if the shin splint symptoms are tolerable and adequately controlled with conservative care. Consultations with a qualified foot and ankle specialist will help in making a decision.

Shin Splint Complications

Tendonitis (inflammation of the tendon) can cause degeneration of the tendon and may be relieved with anti-inflammatory medications and/or correcting any biomechanical abnormalities. Improper stretching before and after activity will increase the chance of developing tendonitis.

Due to the crowded nature of the lower leg with its numerous tendons, the inflammation fluid can get trapped and apply extra pressure on blood vessels and nerves. This condition is called compartment syndrome [2, 3]. The fluid pressure acts as a tourniquet on the blood vessels, strangulating the muscles below the inflamed site. The tissues do not receive adequate nutrition and oxygen needed to function properly. Waste products collect in this area mimicking shin splint symptoms. If nerves are affected, then tingling, numbness, and/or muscle weakness can develop. With rest or massage, the blood flow is restored and the pain subsides. If unusually extreme pain is noted in the calves without resolution, an emergency situation may be present. Sensation deficits in the foot or loss of active foot movement should immediately be addressed by an emergency room physician.

Excessive strain on tendons and their bony attachments can lead to a stress fracture of the tibia. Repeated pull on the bone by the tendonous attachments creates a focal weakened area. Continued forces applied to this weakened area can result in a stress fracture. Fractures generally require leg immobilization for a minimum of six to eight weeks in a cast to allow for proper bone healing.

Conclusion

With minor symptoms, simple modalities like rest, heat and ice, and anti-inflammatory medications can heal shin splint syndrome. Shoes should be checked or changed with continued pain. Orthoses are often beneficial if shoegear change and other treatments fail to resolve the symptoms. The severity of pain will determine how aggressively to approach treatment. Whether you suffer from anterior or posterior shin splints, early recognition of the signs and symptoms and understanding of the appropriate treatment options will ensure successful athletic training and good physical health. If symptoms persist or increase in intensity, seek immediate medical advice to avoid potential complications.

References

1. Barry NN, McGuire JL: Acute injuries and specific problems in adult athletes. Rheum Dis Clin North Am, 22(3): 531-49, 1996.
2. Jones DC, James SL: Overuse injuries of the lower extremity: shin splints, iliotibial band friction syndrome, and exertional compartment syndromes. Clin Sports Med, 6(2), 273-90, 1987.
3. Touliopolous S, Hershman EB: Lower leg pain: diagnosis and treatment of compartment syndromes and other pain syndromes of the leg. Sports Med, 27(3): 193-204, 1999.
4. Michael RH, Holder LE: The soleus syndrome: a cause of medial tibial stress (shin splints). Am J Sports Med, 13(2), 87-94, 1985.

Additional Reading List

1. Abramowitz AJ et al: The medial tibial syndrome: the role of surgery. Orthop Rev, 23(11): 875-81, 1994.
2. Batt ME: Shin splints: A review of terminology. Clin J Sports Med, 5(1), 53-7, 1995.
3. Beck BR, Osternig LR: Medial tibial stress syndrome: the location of muscles in the leg in relation to symptoms. J Bone Joint Surg, 76A(7): 1057-61, 1994.
4. Detmer, DE: Chronic shin splints: classification and management of medial tibial stress syndrome. Sports Med, 3(6): 436-46, 1986.
5. Ilahi OA, Kohl HW: Lower extremity morphology and alignment and risk of overuse injury. Clin J Sports Med, 8(1): 38-42, 1998.
6. Kortebein PM et al: Medial tibial stress syndrome. Med Sci Sports Exerc, 32(3) S27-32, 2000.
7. Sommer HM, Vallentyne SW: Effect of foot posture on the incidence of medial tibial stress syndrome. Med Sci Sports Exerc, 27(6): 800-3, 1995.

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