Shin Pain

‘Shin splints’ describes the mid-shin discomfort experienced by runners during or after activity and represents several diagnoses, including chronic exertional compartment syndrome (CECS), tibial stress fracture and medial tibial periostitis (MTP), as well as vascular and nerve entrapment disorders. These conditions often co-exist and require a detailed management approach (Table 1).

Table 1: Common features of shin pain in athletes

Diagnosis	Pain	Associated Features	Investigation
Chronic exertional compartment syndrome (CECS)	None at rest, aching and tightness builds on exertion after specific duration	May develop parathesia secondary to nerve compression with raised compartment pressures	Invasive exertional compartment pressure testing
Tibial stress fracture	Localised sharp pain with subcutaneous tenderness	Pain exacerbation with tuning fork	X-ray, MRI, CT or bone scan
Medial tibial periostitis (MTP)	Diffuse ache, medial tibial border	Worse in morning or after exercise	MRI, bone scan, diffuse uptake; clinical diagnosis

Biomechanical abnormalities such as pes planus/cavus may predispose an individual to shin pain (Box 1). A cavus deformity results in reduced force dissipation on foot strike with greater force transferred to the shin. Pes planus causes excessive foot pronation, increasing the distance across which the shin muscles must act to drive the body forwards during the propulsive phase of gait. Tightness of the calves and hamstrings also place additional strain on surrounding structure such as the shin, resulting in injury. A formal gait assessment in a running shop or with a physiotherapist or podiatrist may reduce the risk of developing certain injuries.

Box 1: Lower limb biomechanical considerations Pes planus (flat foot); Pes cavus (high arch); Genu valgus (knock knee); Genu varus (bow legged); Tight hamstrings; Tight calves; Squinting patellae; and/or Leg length discrepancy.

Chronic Exertional Compartment Syndrome

In CECS, the pressure within the fascial compartment becomes elevated during exercise resulting in tissue hypoperfusion and pain with a typical pattern of onset after a certain time or distance. The individual often complains of ‘tightness’ that worsens with continued activity and eases rapidly on cessation, leaving an aching sensation. The anterior and lateral compartments are most commonly affected.

Examination at rest may be normal, but after exercise the affected compartment may feel tense and tender. The diagnosis may be confirmed via invasive monitoring by demonstrating increasing compartment pressures during exercise, which may require referral to specialist centres equipped with such facilities.

Management initially involves reduction of aggravating activity; however this is usually not curative. Soft tissue therapies such as massage and vacuum cupping, as well as stretching of the affected muscles and fascial compartment may provide some relief. However, surgical treatment is often required. Fasciotomy is the most common technique, but removal of a portion of the fascia (fasciectomy) may also be necessary. Surgery for CECS has good outcomes with the majority (80%) of individuals making a successful return to sport.

Tibial Stress Fracture

Tibial stress fractures are a relatively common cause of anterior shin pain in distance runners. The majority (90%) occurs in the posteromedial tibia and are considered amenable to management. However, a small proportion occur in the anterior tibia. These fractures develop under tension as a result of the anterior bowing shape of the tibia and thus are notoriously resistant to treatment with a high risk of complications.

Stress fractures often occur after an increase in training intensity or duration, presenting with shin pain of gradual onset that is exacerbated by exercise and may be present at rest or at night. On examination, there is usually localised tenderness of the tibia with occasional soft tissue swelling. Any individual with an injury that is suspicious of a stress fracture should be referred to the emergency department or fracture clinic for further assessment and management. X-ray may demonstrate a ‘dreaded black line’, although further investigation with computed tomography (CT), magnetic resonance imaging (MRI) or a bone scan is often warranted to confirm diagnosis.

Initial management involves resting the affected area and may require partial or non-weight bearing with crutches and/or a pneumatic brace. The return to activity is governed by the clinical response to treatment with an absence of localised bony tenderness and pain-free mobilising indicating successful healing. The individual is advised to undertake low impact activity initially, i.e. swimming, and progress gradually to weight bearing activities. Intrinsic factors such as bone mineral density must also be considered with stress fractures, especially in women (see Femlae Athlete Triad). Surgery in the form of bone grafts or intramedullary nailing may be required for anterior tibial stress fractures.

Medial Tibial Periostitis

Medial Tibial Periostitis (MTP) has a female preponderance and occurs when excessive traction forces are exerted upon the origin of tibialis posterior, soleus and flexor digitorum longus, commonly as a result of the repeated ankle movements during running. Individuals describe pain along the posto-medial border of the shin that ‘warms up’ with exertion and worsens after exercise, noted as an aching after prolonged rest or sleep.

Biomechanical factors (Box 1) may predispose an individual to MTP, as may a recent increase in training, incorrect footwear and reduced lower limb muscle flexibility. On examination, there may be a diffuse area of tenderness, with pain on hopping or on percussion and as such it is important to exclude tibial stress fracture and consider CECS as a differential diagnosis. X-ray is usually normal and the diagnosis is established on clinical grounds, although MRI or bone scan may demonstrate diffuse non-specific changes along the border of the tibia.

Initial management with ice, reduced activity and NSAIDs controls pain and localised inflammation. Correction of abnormal biomechanics is essential and may take the form of orthotics to provide medial arch support, using shock absorbing footwear and encouraging stretching of tight calf muscles. Soft tissue therapy through massage and vacuum cupping may also provide some symptomatic relief. Surgical release of the muscle from the postero-medial tibia has reasonable success rates but is usually only considered for intractable cases.