July 26, 2005
Shin Splints: A Simplified Clinical Classification
by Stephen M. Pribut, DPM
Looking at a list of what's in and what's out: the term shin splints is out and the terms medial tibial stress syndrome, compartment syndrome and stress fracture are all in. Recently, the term shinsplint was medically used to encompass almost all problems occurring in the lower leg. These problems included both bone and soft tissue problems and those that overlapped. They were jumbled into several categories which poorly represented reality. The previous categories in use were anterior, posterior, medial and lateral. Most athletes have used the term shin splint to refer to pain occuring either in the anterior or the medial portion of the leg. This correlates well with the type of problems that are most often clinically seen and will be discussed here. Problems that occur in the lateral aspect of the leg are usually either fibular stress fractures or peroneal tendon injuries following an inversion injury of the ankle. Posterior leg pains are frequently injuries to the posterior muscle group at the myotendinous junction of the calf muscles and achilles tendon or early achilles tendonitis.
In this discussion we will not dwell on serious compartment syndromes, that topic will be saved for a later date.
Medial Shin Splints
The outmoded term medial shin splints has been replaced by the term medial tibial stress syndrome. Either term is fine, the pain is at the medial aspect of the leg, adjacent to the medial tibia. Tenderness is usually found between 3 and 12 centimeters above the tip of the medial malleolus at the posterio-medial aspect of the tibia. When the tibia is palpated (touched) the tenderness is not directly medial, but just behind the most medial portion of the tibia, in the mass of soft tissue that is there and at the bone itself. Periostitis sometimes occurs in this location. The sore, inflamed structures usually include the medial muscles and tendons here. Most frequently involved is the posterior tibial tendon and muscle, but the flexor digitorum longus and flexor hallucis longus may also be involved.
“...the tenderness is not directly medial, but just behind the most medial portion of the tibia..”
medial shin
Stress fractures can also occur in this area. The definitive test for stress fracture is a bone scan, but false negatives can occur and it is possible that a false positive might occur also, because of the soft tissue and periosteal involvement in this injury. Clinically, physical examination can be used to differentiate between "medial shin splints" and stress fracture. With medial shin splints, (medial tibial stress syndrome, MTSS), the tenderness extends along a considerable vertical distance of the tibia. When a stress fracture is present, tenderness is usually noted that extends horizontally across the front of the tibia.
Risk Factors
The first risk factor is overtraining. Evaluate your schedule to determine what training errors you may have made. Mechanically, pronation is most likely to be the culprit. When the foot pronates the medial structures of the leg are stretched and put under stress, this increases the likelihood that they will become injured. Running on a canted surface, such as the side of a crowned road, can put the upper leg at risk to develop this problem, because the foot of the upper leg is functioning in a pronated position.
Self-Care
Decrease training immediately. Do not run if pain occurs during or following your run. Non-weight bearing exercise may be necessary. Swimming, biking, and pool running can all be used to maintain fitness.
While running on soft surfaces has been recommended for this problem, that is not likely to help a pure MTSS. The foot is more likely to pronate excessively on mushy grass or sand. Packed dirt is ideal, and avoidance of concrete is also helpful. In many cases shoes that are rated high for control of pronation may be helpful. Gentle posterior stretching exercises may help, but control of pronation is more directly related to the cause of this syndrome.
Ice applications following running may offer some relief, but are not curative. If symptoms persist it is important to seek professional medical attention.
Office Medical Care
In office medical care will repeat some of the procedures that you have done. A thorough evaluation of your training schedule, racing schedule and shoes will be followed by a biomechanical evaluation.
Anti-inflammatory medication can be prescribed. The use of physical therapy modalities can also be helpful. I use electrical stimulation (HVGS) and ultrasound to treat this problem. I will also tape the foot to limit pronation and decrease the stress on the medial structures of the leg. Pronation, which is a major contributing factor to this syndrome, in the long run, may be approached with improved shoes, and over the counter or custom orthotics.
Anterior Shin Splints
Anterior shin splints as a proper medical term has disappeared in the past 3 years. The concept of what shin splints are, was vague and wrong before, and is still not perfect. Nonetheless, symptoms may occur in the anterior lateral tibial region, that in the past were called anterior shin splints. Now with the disappearance of that term, they are assumed to be either stress fractures or a form of compartment syndrome. Since we are going to be using a simplified clinical system we can cheat a bit and still use the term anterior shin splints. First let's try to find a clinical way to differentiate "shin splint" from stress fracture.
Most injuries that fit the term "anterior shin splint" are soft tissue injuries at the muscular origin and bony or periosteal interface of the bone and muscle origin. These usually have a longer more vertically oriented area of symptoms and tenderness. The involved section of the upper tibia is usually 5 to 8 centimeters long and about 1 to 2 centimeters wide. Most injuries that clinically seem to be stress fractures have what is called a region of pinpoint tenderness and extend in a horizontal direction. The tenderness is pin point in respect to the fact that a discrete line of tenderness exists, not a pin point shape. This line in many stress fractures of the tibia extends horizontally, but might take a tangential course through the tibia. With those that are horizontal there would be no tenderness found one or two centimeters above or below this discrete line of tenderness.
anterior shin
The non-stress fracture injury to this area may be due to micro tears of the muscle either at the origin or in the fibers themselves. This may occur because of repetitive traction or pulling of the anterior tibial muscles at their site of origin. Repetitive loading with excessive stress, such as that caused by running on concrete, may also play a role in injury to this area. This may result in microtrauma to the bone structure itself.
Some have called the result of the repetitive loading injury and also the traction injury, a form of stress fracture. I usually reserve this term for a linear injury that is more within the bone itself. But, let's stay away from academic debates.
Anterior Compartment Syndrome
One should be aware that a compartment syndrome can occur here. This is usually chronic and repetitive and in some respects different from the acute compartment syndrome seen after serious muscle injuries. It is vital to seek evaluation and treatment, if this is suspected. It is caused by the muscles swelling within a closed compartment with a resultant increase in pressure in the compartment. The blood supply can be compromised and muscle injury and pain may occur. The symptoms include leg pain, unusual nerve sensations (paresthesia) and later muscle weakness. Definitive evaluation is done by measuring the pressure in the compartment with a atheter. The normal compartment pressure is 8 to 10 mm Hg at rest. During exercise the pressure may rise to 50 mm Hg, but rapidly, within 5 minutes, should return to normal. It is clearly abnormal if the pressure exceeds 75 mm Hg during exercise or remains above 30 mm Hg after cessation of exercise. This may require surgical decompression of the compartment.
Runner's At Risk for Anterior Shin Splints
The usual runners at risk for anterior shin splints are beginning runners. These runners have not acclimated to the stresses of running yet. They also may not have been doing an adequate amount of stretching. Poor choice of shoes and surface (i.e. concrete) can also play a role. Overtraining of course can be one of the factors in problems here as in most other running injuries.
The usual mechanical factors seen are an imbalance between the posterior and anterior muscle groups. The posterior muscles may be both too tight and too strong. The effect of too tight posterior musculature has ramifications for the gait cycle at two points. The first time in which too tight posterior muscles have an impact on the anterior muscles is just before and after foot contact (heel for the distance runner). At this time the anterior muscles (anterior tibialis, extensor digitorum longus, extensor hallucis longus) are functioning to slow up the forward and downward (plantarflexion) of the foot. They are acting as decelerators. If the posterior muscles are too tight they will force the anterior muscles to work longer and harder in this decleration. The second point in the gait cycle where the anterior muscles may work too hard is when the foot leaves the ground, at toe off. The anterior muscles should be lifting up, or dorsiflexing, the foot as this time, so that the toes will clear the ground as the leg is brought forward. If the posterior muscles are too tight, the anterior muscles again will be working harder than they should be. Logically, downhill running will also have an adverse effect on the anterior muscles.
Repetitive impact on hard surfaces is another frequently associated factor. Excessive pronation may be a minor factor, but it is a much greater factor in the medial tibial stress syndrome (medial shin splints).
Key Causes and Solutions
The key factors to correct will be:
* Tight posterior muscles
* Imbalance between the posterior and anterior muscles
* Running on concrete or other hard surfaces
* Improper Shoes - inadequate shock protection
* Overtraining
Self-Care
Decrease training immediately. Do not run if pain occurs during or following your run. Non-weight bearing exercise may be necessary. The goal will be to find the distance which can be run, if any, that does not produce symptoms. The goal is not to find what your real limit is. Swimming, biking, and pool running can all be used to maintain fitness. Review your stretching and think about what good habits can keep you out of the doctors office.
The posterior muscles should be gently stretched, as
“Do not run on concrete!”
discussed in my section on stretching. I recommend gentle stretching of the calf muscles and the hamstrings.
Shoes with too many miles on them should be replaced. Shock absorption should be a factor in selecting shoes in the individual with anterior shin splints.
Downhill running can aggravate this problem and should be avoided. Too long a stride can also delay healing. Most of all, DO NOT RUN ON CONCRETE!
After exercise icing can be done to lessen symptoms.
Office Medical Care of Anterior Shin Splints
In office medical care will repeat some of the procedures that you have done. A thorough evaluation of your training schedule, racing schedule and shoes will be followed by a biomechanical evaluation. A bone scan can be used, if necessary to evaluate for the possibility of stress fracture. A wick catheter test can be used, if necessary, to measure post exercise compartment pressure, if a compartment syndrome is suspected.
Anti-inflammatory medication can be prescribed. The use of physical therapy modalities can also be helpful. I use electrical stimulation (HVGS) to treat this problem. I will also sometimes use a heel lift to reduce the pulling effect of tight posterior muscles. While this does increase the distance the foot must be dorsiflexed, the duration of action and the effective strength of the posterior muscles is decreased.
Orthotics may also be considered when biomechanical abnormalities exist and problems persist.
