Lower leg pain could be more than shin splints

Back when I was in high school (way back when), all-weather running surfaces were replacing old cinder tracks.

With the change, rain wasnt an issue, times were faster, performances improved almost overnight and we all couldnt wait to run on these new surfaces. When one was installed at our school, it wasnt long before some runners were doing their training just inside the track on the grass because of shin splints.

Since such times, practically every instance of pain in the lower leg (between the knee and ankle) has been attributed to "shin splints," but there are other things that could lead to pain in the lower leg. During an examination, the doctor considers a "differential diagnosis," or what are the potential diagnoses that could cause the same signs and symptoms — something a doctor does every time they examine a patient.

There are lots of things in lower leg — muscles, fascia, two bones, blood vessels, nerves, tendons, and ligaments — that can all lead to some type of pain.

So, in no particular order of importance, here are some likely culprits in lower-leg pain. The actual treatments for each are beyond the scope of this article.

Stress fractures
Excessive, repetitive loads can lead to a stress fracture; an injury to bone. An abrupt increase in the training load (as frequency, intensity or duration) is usually coupled with inadequate rest.

The rest period is when tissues adapt to training and bone adapts to training by becoming denser. A lack of rest means the bone cant fully adapt. When fatigued muscles pull on bone, some small damage to the bone can occur.

There are other factors to consider, such as hormonal imbalances, bone diseases, and sleep deprivation, among others. These are more common in women usually, and part of the so-called female athlete triad (the other two are eating disorders and dysmennorhea).

Routine X-rays can show a healing stress fracture, not a fresh injury. Other imaging studies (such as a bone scan) are better for the diagnosis and MRIs are also used. The location and injured bone dictate the treatment.

Fractures
Tibial and fibular fractures are not all that common in sports like soccer or in endurance sports. Most occur in the lower third of the bones. And despite what most people think, shin pads are not designed to prevent fractures any more than a football helmet is designed to prevent concussions.

In soccer, these fractures usually happen from cleats up during a tackle, especially a sliding tackle, or other hard blow to the leg. You probably have seen the picture on the Internet of that lower leg fracture while shooting.

While Donovan McNabb fractured his fibula early in an NFL game and still finished the game, when one of these bones breaks, there generally is little doubt.

Shin splints (or medial tibial stress syndrome, MTSS)
Pain from this syndrome is usually deep in the leg down the middle and back of the tibia. Pain comes from some anatomical location, but there is no real consensus on the exact location of the injury or what causes the injury.

Bone has a covering called the periosteum (peri- around; ost- bone) and tendon tissue intertwines with the periosteum at a muscles insertion to bone. The current belief is that overuse by muscles pulling on the tendon pulling on the periosteum causes an inflammation of that periosteum.

Rest is required for the inflammation to heal. If the athlete keeps training, the periosteum may pull away from the bone, and no one knows for sure if this injury can heal by itself back to the tibia, thus the pain. X-rays usually are normal and MRI is still experimental, leaving bone scans the preferred method of imaging.

Compartment syndrome
The soft tissues of the lower leg are contained in four compartments: front, the outside, and two in the back. These compartments are enclosed by a very tight tissue, or fascia.

The compartment on the front is like a triangle where two sides are the bones and the third side is the fascia. During exercise, the muscles swell with blood, but the fascia and bones restrict how much the muscles can expand.

In some people, this fascia is very tight and when the muscles swell with blood with nowhere to expand; pain is the result. The diagnosis is one of excluding other causes of pain as well as the history of pain; usually the pain increases with exercise and decreases with rest.

Should the history and physical point toward a compartment syndrome; the doctor may order a pressure test to confirm the diagnosis. A probe is inserted into the muscle on the front of the leg and a pressure reading is taken at rest and at exercise. If the pressure difference reaches a certain threshold, then surgery can be performed.

Other causes of pain

Proximal tibiofibular instability: This occurs where the tibia and fibula attach up near the knee — that knot on the outside of your knee about 1 to 2 inches below the knee. This junction may be disrupted by major trauma.

Nerve entrapments: Any of the major nerves serving the lower leg and foot can become trapped by muscle contraction or odd arrangements of connective tissue around the nerve. When the nerves become squeezed, pain can occur.

Tibiofibular synostosis: A very tight ligament holds the tibia and fibula together. During a traumatic dislocation of the ankle, these two bones could be pried far enough out of parallel to damage this ligament. If left alone, the recovery may lead to a calcification at the point of damage linking the tibia and fibula by new bone growth. Surgery is required only in cases that do not respond to treatment. You may have heard a variation of this injury also called a high ankle sprain by the media.

Venous thrombosis: A thrombosis is a moving blockage of a vein. The pain felt is accompanied by swelling in the calf, behind the knee, or the thigh, and the area may be tender anywhere. The throwing athlete can have something like this in their arm while occurrences in the leg are very rare.

PVD: A heart attack is blockage of an artery feeding the heart. Peripheral vascular disease (PVD) is the same thing in the legs. Exercise leads to pain that is relieved only by rest. This is a disease of aging not found in the young athlete, but an older relative might mention it when lower leg pain is discussed.

As you can see, leg pain can be a result of many different causes. To simply call any leg pain "shin splints" may mean someone is neglecting a problem that is far worse.

A physician, in particular a physician familiar with exercise-induced leg pain, should evaluate any circumstances of lower leg pain.

Copyright 2002 Donald T. Kirkendall

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