Shin splints

Shin and calf pain is extremely common in runners and can be quite a challenge to treat. Such injuries can often plague a runner for several months and cause a lot of frustration as they can be slow to settle. It is advisable to seek expert help early so that a correct diagnosis can be made and treatment started promptly.

The lower leg is composed of two bones - the tibia and fibula - and four muscle compartments. The compartments are bound by a strong tissue called fascia.

Cross section through the lower right leg
(looking down towards foot)

Runners who develop shin pain which is brought on by exercise often complain of "shin splints". This is not a very specific term and should be avoided if possible. There are several different conditions which can cause shin pain and, for the physiotherapist or sports medicine specialist, differentiating between these is the key to the right treatment.

Medial Tibial Stress Syndrome (MTSS)
This is very common in runners who will describe pain in the shin brought on by running which may take hours or days to settle afterwards. There is tenderness over the inner border of the lower 2/3 of the tibia which is due to a "stress reaction" of the lining of the bone on the inner border of the tibia where the posterior tibialis muscle attaches. It is often associated with abnormal biomechanics, especially overpronation. It can also occur if there has been excessive running on hard surfaces and/or if trainers are worn out. Treatment consists of a period of rest from running, maintaining cardiovascular fitness by cycling, swimming etc., and physiotherapy in the form of ultrasound, interferential and flexibility and strength work for the calf, Achilles tendon and ankle. Correction of any biomechanical abnormalities is important and your sports orthotist will work in conjunction with your physiotherapist for this. Finally, your training programme will need to be assessed to identify, and change, any training errors which may have contributed to the condition. It is important that your doctor or physiotherapist excludes a stress fracture of the tibia and, if they are at all suspicious of one, they may organise an x-ray (although a standard x-ray is often normal in the first month after stress fracture) or preferably a bone scan.

Tibial Stress Fracture
Stress fractures are "overuse" injuries of bone to the point of mechanical failure. A repetitive strain, secondary to the loading which occurs during running, causes bone trauma on a microscopic scale and, if not identified early, this can progress to a stress fracture. As with MTSS there is shin pain during a run which persists after the run. The pain occurs at an earlier stage with each successive run and often lasts longer afterwards. There may be a "crescendo" pain at night in bed. There is a localised tender point over the fractured area of the tibia. A bone scan will show a localised area called a "hot spot" which is the stress fracture. Standard x-rays may initially be normal but will later show an area called a "callus" (re-modeling of bone) . Treatment can depend on exactly which part of the tibia has a stress fracture but, typically, a period of total rest from running (try using a flotation vest in the water instead) for 6-8 weeks is required. This is followed by a graded return to running, alternating running with non-weight bearing activities initially, starting at low mileage and gradually increasing if the leg remains pain-free. Any biomechanical abnormalities should be addressed and, as with MTSS, the pre-injury training programme needs to be scrutinised. Some stress fractures take longer to heal, the length of time varying with the individual. Occasionally immobilisation in a plaster cast is necessary. Stress fractures are more common in females and may be associated with over training, low body weight, amenorrhoea (lack of periods) and osteoporosis (bone thinning). If so, this should also be addressed by your doctor. The overlap between tibial stress fractures and MTSS is great and for this reason I would re-iterate my earlier advice - do seek help from a chartered physiotherapist or a sports medicine specialist earlier rather than later.

Chronic Compartment Syndrome (CCS)
This occurs when the pressure within one of the muscle compartments of the lower leg increases during exercise, to the extent that the blood supply in the small vessels is reduced and the muscles, and sometimes nerves, in that compartment are compromised. It can be caused by increase in size of the muscles which become too big for the inflexible surrounding fascia. It is most common in the anterior and the deep posterior compartments (see diagram) and may be associated with oversupination or overpronation respectively. The superficial posterior compartment (containing the calf muscles gastrocnemius and soleus) does not get affected as the surrounding fascia is loose. The pain will occur during a run and is typically relieved by rest. It may feel like a" cramp", a "tightness" or sometimes a "burning". Often the sports medicine specialist can find no abnormality on examination as it only occurs during exercise. They will therefore need to do special pressure studies whilst you are running to obtain a diagnosis. Although rest may ease symptoms, they tend to recur on resuming training and the treatment of choice is opening the compartment surgically (fasciotomy).

N.B. Chronic compartment syndrome is different from acute compartment syndrome, which occurs after trauma and requires IMMEDIATE attention. Acute compartment syndrome is not discussed here.

Calf Sprain
A tear of one of the superficial calf muscles (gastrocnemius or soleus) is best treated initially by RICE (rest, ice, compression, elevation). Early physiotherapy can be beneficial and treatment is along the lines of Achilles tendon treatment (as discussed fully last month). Remember that, as with most injuries, prevention is better than cure – thorough warming up and down with stretching of the calf muscles, and the other leg muscles, is very important with all exercise, not just running (from personal experience, this is often overlooked when cycling).

Some of the other causes
of lower leg pain are:-

Referred pain from the lower back
(this should always be checked by your physiotherapist or doctor as it is fairly common)

Local nerve compression
Rarely, entrapment of the artery at the back of the knee.

Always remember that once a lower leg injury has been treated it is important to look at what caused it.