1. Joints are kept supple.
2. The formation of pathological bands and adhesions is prevented.
3. Repair of all normal structures, even of bone, is hastened.
Any attempt at movement which is inimical to their repair is attended by pain and reflex antagonism to the movement. Thus passive movement is rendered impossible.
4. The elasticity of the muscles is maintained - by no means an unimportant point in cases of paralysis.
5. The circulation of the venous blood and of the lymph is assisted materially, and hence the removal of waste products, of extravasation and of oedema is hastened.
6. The restoration of any disorganisation in the vaso-motor system is probably assisted very materially - the main factor in effecting repair of injured structures.
7. The joint-sense is re-educated, or its loss is prevented, as the case may be, and thus the main link in the reflex of co-ordinated movement is restored or maintained.
8. The way is paved for the prescription of active movement. Let us for one moment contrast these beneficent effects with those that follow the administration of movements in the absence of active relaxation on the part of the patient: -
1. In the absence of relaxation the movement of the joint is forced, and therefore strain is placed upon it. The result is that any synovitis or other pathological condition is perpetuated or increased.
2. There is great danger of inflicting further injury on the already damaged structures, so that adhesions of greater density and strength will ultimately form.
3. Repair is retarded owing to undue strain on the structures that are undergoing repair.
4. The muscles are strained, and possibly even torn, in their vain attempt to resist the movement.
5. The circulation of the venous blood and of the lymph may be assisted, but extravasation will be increased; and
6. The disorganisation of the vaso-motor system is increased as the result of repetition of trauma, and so oedema increases in proportion as repair decreases.
7. The joint-sense is outraged by repeated trauma, and all power of co-ordination is thereby destroyed.
8. Pain being the most powerful of all agencies in inhibiting active movement, the ability to make use of active movement as a therapeutic agent is jeopardised. Small wonder then that those who are only acquainted with the result of "passive" movement administered without relaxation should condemn it and insist only on the prescription of active movement. But those who are able to appreciate all that I have endeavoured to express in the term "relaxed movement" cannot fail to realise its unique value as a means to the end, viz., restoration of function.
The confusion which exists as to what is meant by "passive movement" has, perhaps more than anything else, tended to postpone the more general adoption of the treatment of recent injury by mobilisation. It must be realised from the outset that "passive movement" is impossible if there is any impediment to be overcome, or if the muscles assist or resist the movement. Also, it can only be performed when the joint is moved in the direction in which, during natural activity, there is the least possible strain on any structure surrounding it. Thus, extension of the elbow, if performed without due respect for the carrying angle, lays a strain on the external lateral ligament of the joint. The movement at once degenerates into a forced movement. To prescribe, as is so often done, treatment by "massage and passive movements" for a stiff joint would be ludicrous were it not for the great harm that such prescription produces. The masseur either relies on massage to effect that which it is impossible it should perform, or administers forced movement. In the latter event he may fail to discriminate between "passive" and "forced" movement; and, when true passive movement is required, he may do great damage.
From what has been said it will be evident that true passive movement can only find a very small place in physical treatment. So, too, does, or should, massage. But just as massage is frequently prescribed or given when voluntary effort on the part of the patient is the only thing that can cure him, so "passive" movement may also be given. Massage, used properly, in the right way at the right time, is one of the most valuable of physical remedies. Used wrongly at the wrong time, it is never merely useless but actively detrimental, mentally or physically. The same may be said of passive movement, though the harm done is never serious if the laws governing its administration are respected. Rather is it detrimental in so far as it can replace beneficial treatment in the form of active movement, and hence can retard recovery.
But though the place of passive movement in treatment may be small, it is one of the greatest possible importance in all cases of recent injury. It is, in short, the only prophylactic measure we possess by which we can reduce subsequent stiffness, rapid loss of power and of the joint and muscle sense. One example alone must suffice. After fracture through the shaft of the humerus it may be impossible for the patient to move the elbow unaided for two to three weeks. Absolute fixation of the joint is the worst possible treatment it could receive if there is any traumatic arthritis present as the result of the accident. The triceps and brachialis anticus also are bound, in greater or less degree, to be matted down firmly to the site of fracture. So firm may their adherence become that movement of sufficient strength to free them would tend severely to damage the union. Early mobilisation, on the other hand, by pure "relaxed" movement may well have restored almost complete movement after a similar lapse of time.
In short, the aim of passive movement is to secure movement whenever active movement is, for any cause, impossible. This is its only justification; and, if we can secure to the patient the benefits enumerated above during the whole, or even part, of the time that active movement must be withheld - at the one time of all others, be it noted, that these benefits are of the greatest value - then, as it seems to me, in passive movement we have a remedy that may be truly described as invaluable. Forced movement at the right time and place is of great service too; but intelligent use of passive movement often reduces the condition for which forced movement is required to a negligible quantity. There can be no possible excuse for substituting the one for the other in treatment, for between them lies another agency - potent for great good - unassisted active movement.