Anterior and Posterior Shin Splints

Shin splints are a common problem which cause pain in the lower leg. Shin splints can be broken into two basic categories;
Anterior Shin Splints -
Anterior shin splints are considered an overuse syndrome of the tibialis anterior muscle and tendon. The symptoms of anterior shin splints occur at the origin of the tibialis anterior muscle and tendon (the origin of a muscle and tendon is where it begins and is anchored to the bone). In the case of anterior shin splints, the origin is the tibia, or shin bone. Anterior shin splints are the most common form of shin splints.
 Tendon affected tibialis anterior Tendon function deceleration of the foot in swing phase and heel contact Location of pain front of the shin and ankle
Treatment of anterior shin splints
Diagnosis of anterior shin splints is usually based upon the location and character of the symptoms. Diagnostic testing may include x-rays, bone scans or MRI studies to rule out tibial stress fractures.
If we recognize the fact that anterior shin splints are a mechanical problem, we are safe to assume that a mechanical solution is in order. The key to treating anterior shin splints is to change the functional length of the tibialis anterior muscle and tendon (biomechanical changes). The symptoms of inflammation may be treated concurrently, but without treating the mechanical component of anterior shin splints, recurrence is likely.
Biomechanical changes can be fairly simple and consist of two changes.
 1. Decrease the length of stride. Taking shorter steps decreases the functional length of the tibialis anterior and subsequently reduces the pull of the muscle on the tibia.
2. Modified arch support to decrease the functional length of the tibialis anterior. This can be accomplished by extending the arch of an arch support or orthotic distally to reach under the first metatarsal and big toe joint. Changes should be made slowly and incrementally. As you build up and extend the arch, you are decreasing the functional length of the tibialis anterior.
In addition to treating the mechanics of anterior shin splints, additional care can be used to soothe the inflammation associated with this condition. This becomes increasingly important as the severity of the condition increases. Ice before and after activity helps. Anti-inflammatories or ultrasound treatments also help. As a last resort, rest is helpful but never a final solution. Rest can be as simple as a decrease in activity, a walking cast or even a cast with crutches. It is important to recognize that rest without treatment of the biomechanical origin of this condition will never be a final solution.
 
Posterior Shin Splints -
Posterior shin splints are seen less often than anterior shin splints, but are none the less, just as uncomfortable. The onset of pain and the location vary just a bit;
 Tendon affected tibialis posterior Tendon function support of the medial arch and plantarflexion of the foot at toe off Location of pain behind the medial malleolus (inside ankle bone)
The posterior tibial muscle originates from the back of the tibia, deep to the calf muscle. As it descends the leg it narrows to become the posterior tibial tendon. As the posterior tibial tendon descends the leg, it follows a path immediately behind the posterior aspect of the medial malleolus (ankle bone) making an abrupt turn to continue to the medial arch. In the arch of the foot, the posterior tibial tendon branches into nine different insertions in the bottom of the foot. Posterior shin splints are a true form of tendonitis and occur in the body of the tibialis posterior tendon behind the medial malleolus (inside ankle bone).
 
Treatment of posterior tibial shin splints
To effectively treat any form of tendonitis, we must realize that tendonitis is an over-use condition. Therefore, effective treatment lies either in modifying the way the tendon functions (biomechanical changes) or changing the activity that contributes to overuse. We know that the function of the tibialis poster tendon is to support the arch. Subsequently we can support the function of the tibialis posterior tendon by supporting the arch with a rigid arch support. The tibialis posterior can also be helped by elevating the heel with a firm heel lift and by performing calf stretches to weaken the calf muscle. The calf muscle has a significant influence on the function of the posterior tibial tendon. For more information see the 'additional information' tab on this page.
Part of treating shin splints is treating the inflammation found in both anterior and posterior shin splints. Treatment of inflammation is essentially the same in either posterior or anterior tibial tendonitis and includes ice, medications, ultrasound or rest.
Nomenclature:
Functional length of a tendon - every muscle and its' associated tendon have a normal range of excursion of length in which they are accustomed to working. This normal length is referred to as the functional length.That length of function
Shin - refers to the lower leg, more specifically, the tibia or larger bone of the leg.  
Anatomy:
Anterior shin splints -
Knowing the origin of the tibialis anterior muscle becomes important when trying to differentiate the many cause of shin pain. First, let's take a look at some simple anatomy. As we mentioned, the tibialis anterior muscle and tendon originate from the front of the tibia or shin bone. This origin begins just distal to the knee and continues halfway down the leg, therefore we can say that the origin of the tibialis anterior muscle is the proximal half of the tibia. Also, the origin is not just on the front of the tibia, but actually tucked a little under the lateral or outside edge of the tibia.
Posterior shin splints -
The posterior tibial muscle originates from the back of the tibia, deep to the calf muscle. As it descends the leg it narrows to become the posterior tibial tendon. As the posterior tibial tendon descends the leg, it follows a path immediately behind the posterior aspect of the medial malleolus (ankle bone) making an abrupt turn to continue to the medial arch. In the arch of the foot, the posterior tibial tendon branches into nine different insertions in the bottom of the foot. Posterior shin splints are a true form of tendonitis and occur in the body of the tibialis posterior tendon behind the medial malleolus (inside ankle bone).
 Biomechanics:
Anterior shin splints -
Now let's talk biomechanics. As we walk or run, the tibialis anterior has two functions. The first occurs at heel contact when the tibialis anterior acts to slow the motion of the foot as it hits the ground. Without a tibialis anterior muscle and tendon, the foot would slap the floor. This slowing action is referred to as deceleration and contributes to the controlled gradual motion of the ankle to which we are so accustomed. The second function of the tibialis anterior is to lift the foot during the swing phase of gait. Swing phase is the period when there is no weight on the foot following toe off and just prior to heel contact. During swing phase, the tibialis anterior lifts the foot to prevent it from dragging on the ground.
Quite often the cause of anterior shin splints is over striding. Over striding increases the normal functional length of the tibialis anterior. Essentially, much of the range of motion of a muscle and tendon has to do with the changes in its' overall length. In the case of the tibialis anterior, we know that at heel contact, the muscle acts to decelerate the foot as it hits the ground. As the foot moves to hit the ground, the tibialis muscle and tendon lengthen. So, if we increase the length of stride, the tibialis anterior muscle and tendon lengthen more. In the case of anterior shin splints, the tibialis anterior muscle and tendon cannot keep up with the demands placed upon it and, as a result, begins to find new ways to gain length. Quite often that additional length is gained by the muscle pulling away from it's origin. In the case of the tibialis anterior muscle and tendon, we call that anterior shin splints.
We know that anterior shin splints are common in runners, but let's use an example found in everyday life. Bridgit is a new postal worker. She's 5'2" tall and she's training for a walking mail route in her home town. Her mentor is Jim who has worked the route for years. Jim is 6'3" tall. Jim and Bridgit begin to work together walking the eight mile route everyday. Bridgit really wants to get this new job, so she tries her hardest to keep up with Jim even though she has a hard time. Jim is so much bigger, and to simply keep up, Bridgit has to over stride to compensate for their physical differences. By the end of the first week, Bridgit's in trouble. She has pain in the front of her shins. She has anterior shin splints.
 
Posterior shin splints -
The tibialis posterior muscle and tendon acts as the primary support of the medial arch. The tibialis posterior muscle and tendon also acts to plantarflex the foot at toe off and assists the Achilles tendon in its' function to move us forward.
When we think about treating the symptoms of posterior shin splints, we need to consider the function of the posterior tibial tendon (PT tendon). Many cases of posterior shin splints are caused by increased activities with no control of pronation. The full biomechanical definition of pronation is somewhat complex, but for our discussion, consider pronation to mean flattening of the arch. The mid stance and toe off phases of gait place a significant load on the posterior tibial tendon. The PT tendon will attempt to maintain the normal height of the arch and aid in toe off, assisting the calf and Achilles tendon. If the loads applied to the PT increase faster than what the tendon can accomadate, tendonitis will result.
The PT tendon is easily supported with a rigid arch support during mid stance phase of gait. Load to the tendon can be decreased at toe off by stretching the calf muscle on a regular basis.  
Symptoms:
Anterior shin splints -
Earlier in this discussion we reviewed some anatomy and defined the origin of the tibialis anterior muscle and tendon on the anterior and antero-lateral aspect of the tibia. Anterior shin splint pain is very specific to this location.
In the early stages of anterior shin splints, pain is very similar to that of other forms of tendonitis. Sharp pain on the anterior lateral tibia will be significant upon the onset of an activity. As the activity progresses, the pain subsides until the normal end of the activity is reached, at which time the same pain returns.
In advance cases of shin splints, in addition to the pain with the activity, the origin of the tibialis anterior becomes inflamed and cannot heal. This results in chronic pain from inflammation at the origin of the tibialis anterior.
 
Posterior shin splints -
The signs and symptoms of posterior shin splints are uniquely different from anterior shin splints. Posterior shin splints are the result of inflammatory pain of the posterior tibial tendon. The symptoms of posterior tibial shin splints occur 8-10m cm proximal to the most distal tip of the medial malleolus (inside ankle bone). Swelling may occur but will be slight.
Posterior shin splints exhibit classic tendonitis symptoms. In the early stages of posterior shin splints, pain is noted at the beginning of an activity and seems to 'warm up' over the first five minutes or so of the activity. In advanced cases, pain is constant and can be aggravated by any form of weight bearing.
 
Differential Diagnosis:
Stress fractures of the tibia present with pain similar to anterior shin splints.
Conditions that may resemble posterior shin splints include tarsal tunnel syndrome, tibial stress fractures, posterior tibial tendon rupture, flexor hallucis longus tendonitis, gout, arthritis of the subtalar joint or a fracture of the posterior process of the talus.
This article was written by Jeffrey A. Oster, DPM, C.Ped