Marathon season has arrived and with only seven weeks to go before the London Marathon most runners are nearing peak training volumes. It is at this time in the season that injuries start to creep in, with shin splints being one of the more frequent running concerns.
“Shin splints” or exertional shin pain describes a number of quite distinct mechanisms and diagnoses. It encompasses a spectrum of abnormality from minor overload of the muscle, tendon and bony structures at the front/inner aspect of the shin, to a stress fracture of the tibia (the main weight bearing long-bone in the lower leg).
Exertional shin pain is usually caused by abnormal running mechanics, overload as a result of a rapid change in the frequency, intensity, duration or type of training; or may be due to underlying medical issues such as low bone mineral density (osteopaenia or osteoporosis) or abnormalities of bone metabolism.
A thorough history and examination allows the clinician to stratify risk and decide upon the best course of management. Investigation, usually in the form of an MRI can be valuable in differentiating between the causes of exertional shin pain and can allow the clinician to offer a likely short-term prognosis, i.e. you CAN or CANNOT run the marathon.
Medial Tibial Periostitis/Stress Syndrome (MTSS): MTSS is a condition involving the muscle origin, along the
inner/front part of the shin. This is thought to arise from increased pulling or traction at the interface of the muscle on the bone, causing localized inflammation of the periosteum (lining of the bone). It is the most common cause of exertional shin pain and is frequently associated with tender, boggy swelling along the inside of the shin (bottom 1/3rd towards the ankle). This type of shin pain tends to ‘warm up’ with exercise but excessive activity may lead to a deterioration of symptoms. MTSS tends to settle with relative rest, but it is essential to address any underlying predisposing factors such as abnormalities of running mechanics, prior to return to training.
Stress Fracture: Bone is a tissue that is in a constant process of being built up and broken down. These processes must be balanced to maintain optimum bone health. If there is insufficient building of bone due to inadequate calorie intake, metabolic abnormality; or increased breakdown due to a change in training intensity, frequency or volume, the net result will be a reduction in bone density and a propensity to a bone stress injury, i.e. bone stress reaction or stress fracture. This type of shin pain tends to worsen with activity to a point where activity must be stopped to alleviate discomfort. It may affect the inner or front part of the shin and may be associated with localized bogginess or swelling. Pain that causes the individual to wake from sleep at night would raise a suspicion of a bone stress injury. Management initially involves reduction of load and stress upon the bone, usually in the form of an aircast boot, with or without crutches. Bone stress (reaction/fracture) is a serious injury and should be diagnosed early to avoid progression and longterm consequences.
Chronic Exertional Compartment Syndrome (CECS): CECS is thought to occur because of tightness and reduced compliance of the fascia surrounding the muscles, most commonly the extensor muscles (that lift the foot up) in the front of the shin. Pain tends to build up as a pressure-type discomfort with ongoing impact activity, most commonly in the compartment on the outer part of the shin. This eventually reaches a point where the individual is unable to continue running and is forced to stop and rest. After several minutes they are able to set off again. Individuals often have little pain at rest, other than tightness and mild discomfort in the affected compartment. Diagnosis relies heavily on a full exploration of the history and symptoms and may require the clinician to observe the individual during and after a run.
Exertional shin pain is likely to respond well to a multidisciplinary approach: involving doctors, physiotherapists, podiatrists, nutritionists, soft tissue therapists and strength and conditioning input.
If you have exertional shin pain, please feel free to get in touch.