Definition

“Shin splints” is best thought of as a clinical syndrome defined in terms of pain and discomfort in the anterior portion of the leg from repetitive activity on hard surfaces or from forcible, excessive use of the foot flexors. The diagnosis should be limited to musculoskeletal inflammations, excluding stress fractures, diet-related diseases [1], and ischemic disorders [2], although it may coexist with such disorders.

Shin splints most commonly occur in athletes who have sudden increases or changes in their training activity. This disorder occurs in runners and in athletes who participate in high-impact court or field sports as well as in gymnasts and particularly ballet dancers, alone or in conjunction with other overuse syndromes [3], but it has also been well documented and studied in military personnel [4–6]. The etiology of shin splints is not clearly defined, but it is likely to be multifactorial with biomechanical abnormalities of the foot and ankle, poor footwear and shock absorption, hard playing surfaces, and training errors. Other contributing factors may include weakness of anterior and posterior compartment musculature, inadequate warm-up, leg length discrepancy, tibial torsion, excessive femoral anteversion, and increased Q angle [7,8], as is seen in women.

One prospective study [6] in military cadets looked at seven anatomic variables and identified greater internal and external hip range of motion and lower mean calf girth to be associated with a higher incidence of exertional medial tibial pain in men. It also showed a high rate of injury among women, but no intrinsic factor was specifically identified. Nutritional and endocrine factors are more likely to play an etiologic role in stress reactions. In school-age athletes and adults who participate in seasonal sports, shin splints can occur when they resume their sport or start a new land-based sport (e.g., high-school or college athletes who go from playing basketball to cross-country or track).

It is important for the clinician to differentiate shin splints, a fairly benign condition, from acute compartment syndrome (a potential emergency) and from the different types of stress fractures that can occur in this region. The anterior lower leg is especially predisposed to compartment syndrome because of its high vulnerability to injury and its relatively limited compartment compliance [9]. It is most common to study these diagnoses together because many may coexist and symptoms overlap. Further discussion of these other diagnoses may be found in their respective chapters. Tibial periostitis has been described as an initial manifestation of polyarteritis nodosa [10]. Primary adamantinoma [11], a rare low-grade primary bone tumor, and hydatid bone disease [12] have also been reported in this region.

Symptoms

Patients presenting with shin splints usually complain of a dull and aching pain near the junction of the mid and distal thirds of the posteromedial or anterior tibia (Fig. 78.1). Clinicians should be aware of the wide differential diagnosis of pain in this region; not all anterior tibial pains are shin splints. Symptoms are commonly bilateral, occur with exercise, and are relieved with rest [13]. Initially the pain may ease with continued running and recur after prolonged activity. Those with more severe shin splints may have persistent pain with normal walking, with activities of daily living, or at rest.

Physical Examination

Physical examination typically reveals generalized tenderness along the medial tibia. Mild swelling may be present. Resisted plantar flexion, toe flexion, or toe raises may aggravate symptoms, and pain-inhibitory weakness may be evident. Striking a 128-Hz tuning fork and placing it on the tibia may reproduce the pain associated with stress fractures. Patients with stress fractures will usually have point tenderness over the bone at the site of stress fracture. Lower extremity idiopathic osteonecrosis is most common in the fifth decade of life at the medial tibial plateau [14], whereas those with shin splints will have more widespread tenderness to palpation that is more distal than these other pathologic processes. However, longitudinal tibial stress reactions may share a common anatomic pain distribution, and one study [15] showed tibial stress reactions in this same distal-third region.

The lower extremity examination focuses on static and dynamic components of the kinetic chain to uncover signs of coexisting lower extremity issues that may be contributing factors. These include forefoot pronation, pes cavus, pes planus, and excessive heel valgus or varus. Comparatively tight or weak lower extremity muscle groups should be noted for later rehabilitation goals. In particular, relative ankle plantar flexion, dorsiflexion, inversion, and eversion strength should be examined. Careful review of systems should be negative for fever, chills, night sweats, unintentional weight loss, and loss of bowel or bladder control. The neurologic portion of the examination, including sensation and muscle stretch reflexes, should be normal.

Functional Limitations

In early stages of shin splints, activity limitations occur most often during running or participation in ballistic activities. When symptoms are more severe, they may occur with walking or at rest, thus causing further functional limitations. Athletes may be unable to participate in their sport, and attempts to cross-train into other sports may result in worsening of symptoms.