Chapter 26
Shin Pain

with Chris Bradshaw

Shin pain is an extremely common complaint among athletes. The term ‘shin splints' has been used in the past to describe the pain along the medial border of the shin commonly experienced by runners. It is, however, necessary to make a more precise pathological diagnosis and, therefore, the term ‘shin splints' should be avoided. 

Shin pain generally involves one or more of three pathological processes. 

1. Bone stress. A continuum of increased bone damage exists from bone strain to stress reaction and stress fracture. 

2. Inflammation. Inflammation develops at the insertion of muscles, particularly the tibialis posterior and soleus, and fascia to the medial border of the tibia. 

3. Raised intracompartment pressure. The lower leg has a number of muscle compartments, each enveloped by a thick inelastic fascia. The muscle compartments of the lower leg are shown in Figure 26.1. As a result of overuse/ inflammation, these muscle compartments may become swollen and painful, particularly if there is excessive fibrosis of the fascia.

Fig. 26.1 Cross-section of lower leg (ADAPTED FROM THE CIBA COLLECTION OF MEDICAL ILLUSTRATIONS , REPRODUCED BY COURTESY OF CIBA-GEIGY LIMITED, BASEL, SWITZERLAND. ALL RIGHTS RESERVED)

(a) The various muscle compartments

 
(b) The individual muscles, nerves and vessels 

These three abnormalities can usually be distinguished on the basis of history, examination and investigations. It is important to remember that two or all three of these conditions may exist together. For instance, it is not uncommon to have a stress fracture develop in a patient with chronic periostitis. Periostitis and muscle compartment syndrome often occur together. This interrelationship is demonstrated in Figure 26.2. 

One of the major causes of all three injuries is abnormal biomechanics. Shin pain occurs in athletes with both extremes of foot type (Chapter 6). A rigid, cavus foot has limited shock attenuation, thus increasing the impact pressure on the bone. In athletes with excessively pronated feet, the muscles of the superficial and deep compartments are required to contract harder and longer eccentrically to resist pronation after heel strike. On toe-off, they then work hard concentrically to accelerate supination. With fatigue, these muscles fail to provide the normal degree of shock absorption. This mechanism may lead to the development of a stress fracture or periostitis and will exacerbate a tendency to develop compartment syndromes. 

Fig. 26.2  Possible interrelationship between the three types of shin pain

The athlete with excessive pronation has a tendency to develop lateral shin pain, especially when pronation occurs during toe-off. During this phase, the peroneal muscles contract strongly in order to stabilize the foot for propulsion. The repetitive force of contraction on the fibula may lead to stress fracture. Tight calf muscles, which commonly occur as a result of hard training, will restrict ankle dorsiflexion and increase the tendency for excessive pronation, leading to increased internal rotation of the tibia. The characteristic features of each condition are summarized in Table 26.1. 

The anatomy of the shin is shown in Fig. 26.3. The causes of shin pain are listed in Table 26.2.

Table 26.1 Guidelines for differentiating between the three main sites of shin pain