Chapter 25

### Objectives

After completion of this chapter, the physical therapist should be able to do the following:

• Discuss the functional anatomy and biomechanics of the lower leg during open-chain and weightbearing activities such as walking and running.

• Identify the various techniques for regaining range of motion, including stretching exercises and joint mobilizations.

• Discuss the various rehabilitative strengthening techniques, including open- and closed-chain isotonic exercise, balance/proprioceptive exercises, and isokinetic exercise for dysfunction of the lower leg.

• Identify common causes of various lower-leg injuries and provide a rationale for treatment of these injuries.

• Discuss criteria for progression of the rehabilitation program for various lower-leg injuries.

• Describe and explain the rationale for various treatment techniques in the management of lower-leg injuries.

### Functional Anatomy and Biomechanics

The lower leg consists of the tibia and fibula and 4 muscular compartments that either originate on or traverse various points along these bones. Distally the tibia and fibula articulate with the talus to form the talocrural joint. Because of the close approximation of the talus within the mortise, movement of the leg will be dictated by the foot, especially upon ground contact. This becomes important when examining the effects of repetitive stresses placed upon the leg with excessive compensatory pronation secondary to various structural lower-extremity malalignments.78,79 Proximally the tibia articulates with the femur to form the tibiofemoral joint, as well as serving as an attachment site for the patellar tendon, the distal soft-tissue component of the extensor mechanism. The lower leg serves to transmit ground reaction forces to the knee as well as rotatory forces proximally along the lower extremity that may be a source of pain, especially with athletic activities.56

#### Compartments of the Lower Leg

All muscles work in a functionally integrated fashion in which they eccentrically decelerate, isometrically stabilize, and concentrically accelerate during movement.50 The muscular components of the lower leg are divided anatomically into 4 compartments. In an open-kinetic-chain position, these muscle groups are responsible for movements of the foot, primarily in a single plane. When the foot is in contact with the ground, these muscle–tendon units work both concentrically and eccentrically to absorb ground reaction forces, control excessive movements of the foot and ankle to adapt to the terrain, and, ideally, provide a stable base to propel the limb forward during walking and running.

The anterior compartment is primarily responsible for dorsiflexion of the foot in an open-kinetic-chain position. Functionally these muscles are active in early and midstance phase of gait, with increased eccentric muscle activity directly after heel strike to control plantarflexion of the foot and pronation of the forefoot.21 Electromyographic studies have noted that the tibialis anterior is active in more than 85% of the gait cycle during running.54

The deep posterior compartment is made up of the tibialis posterior and the long toe flexors and is responsible ...

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