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ROM is how far a joint can move (active range of movement) in a particular direction or be moved (passive range of movement) in a particular direction. Active range of movement is when the person’s own muscles move the joint; passive is when an external force, such as the examining practitioner moves the joint. Passive movement can be greater than active, but rarely the other way round.
In limb joints (hip, knee shoulder etc) and gross areas of the spine (eg neck), It is possible to see both the active and passive mobility. For smaller joints and joints linked closely together (eg the joints of the feet, the superior tibia-fibular joint of the knee, the sacro-iliac joints, the intervertebral joints of the spine) only feeling the movement (palpation) reveals the range of movement
Palpating joint movement also lets the osteopath feel for quality of movement (QOM) and end feel.
A normal joint has two “barriers” to movement. When a joint moves the first barrier encountered is the physiological barrier, created by normal muscle resistance that acts as a brake on the joint. The next is the anatomical barrier, which is created by the tension of ligaments and the shape of the joint. Active movements usually take the joint up to the physiological barrier. Passive movements can take it up to the anatomical barrier. Taking the movement beyond this, as might happen in a fall or sudden strain risks tearing the ligaments or even a fracture.
In joints with a “dysfunction” there is often a reduced ROM (Or QOM) – so there is a third barrier (before the physiological barrier is encountered) called the pathophysiological barrier.
Both active and passive ROM may be reduced due to several factors (the causes of the pathological barrier) – eg pain, muscle contracture on the opposite side to the direction of movement, loose bodies in the joint, osteophytes (bone spurs around the joint), contracted ligaments and joint capsules, inclusions of synovial membrane. It is part of the osteopath’s job to determine what the restricting factors are. Osteopathic techniques aimed at improving movement can then be used appropriately (for example, it would be pointless and foolish to even try to increase mobility that was limited by osteophytes!, but a synovial inclusion could be quickly released by an LAHVT..
Passive movement also has more directions than active movement. The osteopath can take the joint (still within the physiological and anatomical barriers) into directions that the patient’s muscles cannot pull them. These are known as adventitious movements. Often they are movements in directions of translation (gliding) rather than rotation (rolling). For example. in the neck the joints can bend, turn and twist, but not shift sideways (“lateral translation”); in the low back joints can bend and move turn, no forward glide (“anterior translation”). By careful palpation of these adventitious passive movement the osteopath can gain further information about the state of the joint (And they are often incorporated into treatment techniques)
See also: Palpation, Range of movement; end-feel
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