What is it?
Shin pain is felt on or around the shin bone (tibia) and it may be localised or can spread up and down the inside or outside of the tibia. 'Shin splints' is an inexact term that encompasses a few specific conditions causing shin pain. These include medial tibial stress syndrome or tenoperiostitis, chronic exertional compartment syndrome and stress fracture. Occasionally, referred pain from the knee, low back or sacro-iliac joints may result in pain in the shin region.
Symptoms
Medial tibial stress syndrome causes pain and tenderness along the inside of the lower leg. The pain is usually associated with running, and persists for a period of time after the activity ceases. The pain may improve during the run, but recur towards the end or after the activity finishes. The same process can also occur on the outside edge of the tibia, which is why the problem is sometimes referred to as tenoperiostitis. The area along the edge of the bone, where the muscle attaches to the tibia, will be tender.
Stress fracture usually causes localised pain situated at the junction of the upper and middle third of the tibia or the middle and lower third of the bone. The pain in this situation is always with activity and the pain will become progressively worse during a run, and with successive runs. Pain will persist for hours to days afterwards. The bone itself will be tender in this condition.
Compartment syndrome. Pain down the front of the muscular part of the leg, or deep in the calf, can be due to chronic exertional compartment syndrome. Symptoms of compartment syndrome are leg pain, tightness or burning, with sensations such as tingling or pins and needles. The pain will build up during a run, to the point where the person has to stop. On stopping exercise, the severe pain goes away within a few minutes, but a residual ache persists.
Causes
Medial tibial stress syndrome, stress fracture and compartment syndrome are all overuse injuries and the factors that cause them are similar. In particular, both intrinsic factors (concerning the person exercising) and extrinsic factors (concerning the environment) can contribute. They include such things as the person's training programme, footwear, the surfaces run or played on, and the person's biomechanics.
Medial tibial stress syndrome/tenoperiostitis. This results from repetitive stress on the tendon attachment to the bone. It usually occurs along the inside of the bone, but can involve the outer surface either separately or with the inner surface. The condition can be caused by overtraining, running on hard surfaces, with excessive cambers, poorly supportive footwear or can be associated with poor lower limb alignment such as excessive pronation (rolling in of the foot), knock knees or turned-in hips.
Chronic exertional compartment syndrome. This occurs when the large muscle down the front of the shin (tibialis anterior), the deep calf muscles or occasionally the peroneal muscles on the outside of the leg, increase in size during activity with the normal increase in blood flow, but the skin or sheath around the muscle has become very tight. This restricts the blood flow in and out of the muscle and hence as exercise progresses, the pain increases significantly due to lack of oxygen and build up of waste products. Contributing factors to this condition are training errors such as too rapid a build up in training, too much training, biomechanical malalignments and poor footwear.
Stress fractures of the tibia or fibula are overuse injuries that can occur in people who undertake a new exercise program and don’t build up the intensity gradually or experienced athletes that run excessive distances or undertake too many training sessions. Stress fractures of the tibia are especially common in sports involving running and jumping. They are most likely to occur in people who have poor biomechanics, who wear unsupportive footwear and/or run long distances on hard surfaces, or in female athletes who are undernourished, have menstrual irregularities and poor bone density.
Treatment
Medial tibial stress syndrome/tenoperiostitis: Relative rest, or avoiding the aggravating activity, ice and anti-inflammatory medicines are the mainstay of initial treatment, followed by rehabilitation exercises, such as calf stretching and muscle strengthening. Footwear must be assessed relative to the person's individual foot type. If the person has foot or gait abnormalities, orthotics may be recommended.
Chronic exertional compartment syndrome: The treatment of this condition can require up to 3 months of rest from the aggravating activity, footwear assessment and possible orthotic prescription. Stretching and strengthening exercises can be useful and deep therapeutic massage is sometimes recommended. Occasionally, surgery is needed to decompress the muscle compartments.
Stress fractures: Treatment usually involves rest from the aggravating activity, ice, and anti-inflammatory medicines. For runners, swimming or using an exercise bike may be appropriate activity while the fracture heals. A stress fracture may take between 4 and 12 weeks to heal, and occasionally longer, depending on the severity of the fracture itself.
