As mentioned earlier, PROM is usually performed after the client cannot do AROM. PROM testing eliminates the client’s own muscle strength as a variable, as now the therapist supplies the motor for the movement.
This will make the cause of the restriction clearer and will enable the therapist to feel how the joint / body part is moving, in particular towards the end of the movement (endfeel).
Perform PROM if AROM is not OK
PROM should definitely always be carried out whenever a client has difficulty performing the AROM tests. It is used to detect whether a limitation in ROM is consistent both with and without the client’s muscle power.
Multiple Joint Involvement
Passive motion towards the end of joint movement possible will not only stretch antagonist muscles, ligaments and joint capsule, but possibly also compress soft tissue structures like ligaments, bursae and joint capsule (usually on the side of the agonist muscle) and can lead to pain especially if there are adhesions. Learn more
If the restriction is consistent under PROM test conditions, muscle weakness can usually be eliminated as the direct cause, and bone (intra-articular) or soft tissue (extra-articular) blockage is most likely, although muscle weakness may also exist as a result of non-utilisation of the joint.
To distinguish between intra-articular and extra-articular blockage, check the quality and feel of the blockage within the joint. If the blockage has a rubbery feel and gives slightly under pressure, it is likely to be an extra-articular (soft tissue) blockage. If the blockage seems inflexible and range of motion ends abruptly, there is probably an intra-articular (bony) blockage. Learn more
Quality of Movement
Apart from the actual ability to move the body part through the full ROM, the quality of the movement is important as well.
Although clients often can get to the end of the ROM, they might experience pain in some part of the movement (painful arc) or might be hesitant.
Make sure that the client trusts what you are doing. If they are not sure whether you are going to hurt them, they will not relax and PROM results will be inconclusive.