Chapter 3: Range of Motion

Introduction

Range of motion is a basic technique used for the examination of movement and for initiating movement into a program of therapeutic intervention. Movement that is necessary to perform functional activities and desired tasks can be viewed, in its simplest form, as muscles or external forces moving bones in various patterns or ranges of motions. When a person moves, the intricate control of the muscle activity that causes or controls the motion comes from the central nervous system. Bones move with respect to each other at the connecting joints. The structure of the joints, as well as the integrity and flexibility of the soft tissues that pass over the joints, affects the amount of motion that can occur between any two bones. The full motion possible is called the range of motion (ROM). When moving a segment through its ROM, all structures in the region are affected: muscles, joint surfaces, synovial fluid, joint capsules, ligaments, fasciae, vessels, and nerves. ROM activities are most easily described in terms of joint range and muscle range. To describe joint range, terms such as flexion, extension, abduction, adduction, and rotation are used. Ranges of available joint motion are usually measured with a goniometer and recorded in degrees.²⁴ Muscle range is related to the functional excursion of muscles.

Functional excursion is the distance that a muscle is capable of shortening after it has been elongated to its maximum.¹⁵ In some cases the functional excursion, or range of a muscle, is directly influenced by the joint it crosses. For example, the range for the brachialis muscle is limited by the range available at the elbow joint. This is true of one-joint muscles (muscles with their proximal and distal attachments on the bones on either side of one joint). For two-joint or multijoint muscles (those muscles that cross over two or more joints), their range goes beyond the limits of any one joint they cross. An example of a two-joint muscle functioning at the hip and knee is the hamstring muscle group. If it contracts and moves the knee into flexion while simultaneously moving the hip into extension, it shortens to a point known as active insufficiency, where it is too short to produce much tension. This is one end of its range. When it is fully lengthened and limits motion at one of the joints it crosses, it is known as passive insufficiency. This occurs in the hamstring muscle when the knee is extended and full range of hip flexion is limited (or conversely, when the hip is flexed full range and knee extension is limited). Two-joint or multijoint muscles normally function in the midportion of their functional excursion where ideal length-tension relations exist.¹⁵

To maintain normal ROM, the joints and muscles must be moved through their available ranges periodically. It is recognized that many factors, such as systemic, joint, neurological, or muscular diseases; surgical or traumatic insults; ...