The lower leg is the term that describes the portion of the anatomy of the leg that extends from the knee to the foot; there are many musculoskeletal injuries that occur along this entire structure that meet the definition of a lower leg injury. As the joints of the knee, ankle, and foot are each highly specialized mechanisms with unique structural considerations, they are considered on their own and not as part of the lower leg injuries. The injuries described here are those restricted to the tibia and fibula bones, which provide the skeletal framework for the shin and the calf, as well as those injuries involving the tibial and fibular connective tissues.
The mechanisms that cause injuries to the lower leg are almost infinite in their variety. The bones of the lower leg are often fractured through blunt force trauma in contact sports or in high velocity activities such as Alpine skiing or bobsled. The Achilles tendon is the major connective tissue between the gastrocnemius and the soleus, which together are the calf muscles, and the foot. The Achilles tendon is exposed to a number of stresses that can lead to an impairment of its function; the Achilles is often susceptible to either tendonitis, or an immobilizing tear or a rupture of its fibers. The calf muscles can also sustain strains and tears in both contact and non-contact circumstances.
A common lower leg injury that directly impacts both the structure and the function of the lower leg is often characterized as a shin splint. As with many sports injuries, the general term involves a consideration of a number of other more complicated and serious outcomes.
A shin splint is broadly defined as an inflammation of one of the components of the lower leg: the bone, the muscles, or the tendons located below the knee and above the ankle. The symptoms of shin splits are a localized pain while running, that usually becomes more pronounced after the athlete has been running for a number of minutes; the pain persists after the training session has ended. Shin splints can be sufficiently painful to keep an athlete from running for several days at a time. Treatments for shin splints are an extension of the RICE (rest/ice/compression/elevation) treatment, and in most cases, shin splints are a transitory condition. Shin splints are in many cases the result of the unequal forces created by uneven leg length when the athlete's foot strikes the ground during the running motion. This condition is often treated effectively through the use of an orthotic.
When the pain from an apparent shin splint persists, the condition may be one of two other serious lower leg injuries, each of which presents significant treatment issues for the athlete. These potential injuries are compartment syndrome and stress fracture.
Compartment syndrome occurs when the connective tissue surrounding the muscles of the lower leg become the subject of a pressure buildup caused by the fluids in the muscle that are generated through normal athletic activity. Each connective tissue forms a compartment, and the pressure created within each compartment by the muscle fluid can place excessive stress upon the nerve fibers that extend into each compartment. This condition is debilitating, as it prevents the athlete from putting any significant weight on the affected leg. Compartment syndrome may also result in numbness in the lower leg or foot.
The usual and conservative treatment for compartment syndrome is rest, stretching, and the application of the RICE principles; in severe cases, a surgical procedure known as a fasciotomy, which involves a micro-incision of the compartment to relieve the pressure buildup, may be employed.
A stress fracture is a localized break in the bone structure. The tibia is a very common location for stress fractures, as the forces generated by every stride taken by the athlete will radiate into the tibia. Most stress factures are caused by repetitive stresses directed into the specific area of the bone; some stress fractures result from a combination of repetitive forces and an underlying structural problem such as a calcium deficiency that has caused a weakening of the bone.
The nature of the pain associated with a stress fracture is the distinguishing feature between it, a compartment syndrome condition, and a shin splint. A stress fracture will often not be bothersome at the beginning of a workout, but as the stresses on the bone continue, the pain in the area of the fracture will often be excruciating. A stress fracture will not be noticeable when the athlete is at rest.
Due to the very localized nature of the fracture, this condition is not always one that can be pinpointed by way of x ray. A stress fracture also has a lengthy rehabilitation period attached to it; six months is a common time frame for recovery.
All lower leg injuries are ones that can be exacerbated by poor quality footwear and hard, unforgiving training surfaces. Once a lower leg injury arises, the athlete should undertake a complete analysis of the training methods, equipment, and diet, as the combined effects of the physical stresses of the sport and a nutritional deficiency must be eliminated to entirely cure most lower leg injuries.