Normal Sounds. - It is not uncommon to hear peculiar sounds accompanying the normal movement of joints.  These sounds are indicated by popular terms, such as "cracking," snapping" and "popping." They are so common that every one has heard them, either in their own bodies, or those of friends.  Pulling the fingers is the best known method.  It is commonly supposed that such a method, if persisted in, will enlarge the joints.  It is doubtful whether there is any proof of this.  Doubtless the fear of it originated as an effort to frighten some one in whom the phenomenon was easily produced.  Loose jointed people are able to produce sounds in many joints by carrying normal movements to the limit.  Scarcely any movable joint, in which the ligaments and muscles are normally relaxed, is free from the possibility of producing sound, when the opposing muscles are contracted unevenly, i. e., either the flexors or extensors predominating.  The joint surfaces will slip upon each other suddenly, thus producing the sound.  After it has been once made, it is rarely repeated without there has been an interval of rest, during which the muscles change their tension.  The cracking in the tempero-maxillary articulation can be repeated until the structures ache, because it is occasioned by the sliding of the interarticular cartilage on to the eminentia articularis.  The wrist and shoulder are capable of producing frequent sounds, on account of their free movement, and the many directions in which the force is applied.

    Abnormal Sounds. - A large number of sounds which originate in joints are abnormal; i.e., the joints are not normal, or else these particular sounds would not be produced.  Some of these sounds are familiar to all physicians.  They result from forced motion, actively or passively made, in a joint having limited movement as a result of injury; or intracapsular deposits. due to disease.  Another class of sounds is produced by forced movement, passive, in joints having lost some of the normal relations of their surfaces.

    Pathology of Joints Producing Abnormal Sounds. - It may be well to recount systematically the conditions in which passive movement of joints produces sounds.  In this way we can note the difference between the characters of sounds usually recognized by physicians, and those especially peculiar to manipulative treatment of subluxations.

    Synovial Adhesions. - The breaking of adhesions between articular surfaces produces a sound comparable to that occasioned by the breaking of a green stick, in which the fibers break individually as the force becomes greater and greater.  Synovial adhesions are due to many causes, the simplest of which are slight injury and non-use of a joint.  An injury sufficient to cause slight efforts at repair, when accompanied by rest, will result in a few adhesions.  Voluntary movement of the joint is arrested by these adhesions.  Such conditions frequently follow a sprain, or the splinting of a joint just above or below a fracture.  The joint may be quite well, but by keeping it perfectly fixed during the repair of the fracture, the periarticular structures lose their elasticity, and a few adhesions may form within.

    Non-use of a Slightly Sprained Joint. - Sometimes a timid person may be so fearful of using a slightly sprained joint that adhesions form, and control of the joint is lost.  I was recently called to examine a foot, which was very painful and useless.  Seven months previously the ankle was sprained.  The foot had not been used since that injury.  I found the foot stiff, cold and resting on a pillow.  Examination revealed slight motion which seemed to be limited by elastic bands.  There was no inflammation in the foot.  Sudden force, applied first in direction of flexion, then extension, caused a series of cracking sounds, which indicated the rupturing of adhesions.  The range of motion instantly increased.  If these adhesions bad been broken six months before, much of the muscular atrophy of the leg and thigh would have been avoided.

    A patient with broken femur, leaving been kept in bed twelve weeks, was unable to move the knee, on account of adhesions formed during period of non-action due to splinting.  Forcible flexion of the knee a little each day gradually broke the adhesions, until movement was nearly normal.

    These are the cases with which all physicians are familiar.  The sounds produced are not repeated at any time following the first forcible movements.  Such adhesions as these, are due to rest, not without some slight injury, involving the joint structures.  I do not believe that non-use alone is capable of causing adhesions.

    Rheumatic Joints. - Rheumatic joints sometimes manifest conditions similar to sprain.  Adhesions form during the period of inflammation and persist after its subsidence.  Rupturing these by sudden force frequently restores normal movement.

    All the foregoing conditions are the result of some degree of inflammation.  Forced movement breaks the adhesion, which makes a sound as it breaks.  There is no repetition of the sound in succeeding movements.

    Semilunar Cartilages of the Knee. - The semilunar cartilages of the knee joint may become displaced and cause great pain, with loss of motion.  A case recently under treatment gave history of frequent accidents of this kind, while riding a bicycle.  When extending the leg to push the pedal down, the force was exerted with the knee somewhat everted.  Excruciating pain came on suddenly, and the leg could not be extended.  Examination revealed a very sensitive spot at the outer and anterior surface of the joint.  The semilunar cartilage slipped forward and blocked the extension of the joint.  By taking the leg between my knees and making thumb pressure on the painful prominent spot, then gently flexing and slightly rotating the tibia on the condyles of the femur, followed by quick extension, a distinct sound was elicited, and the action of the joint was restored.  The sound indicated replacement of the cartilage.

    "Bone Setting." - It has been supposed that much of the work of osteopaths consisted in breaking adhesions, which were simple enough, but happened not to have been strictly attended to by the surgeons, There is much chance to misinterpret the work of the osteopaths in reducing subluxations.  Medical men of established schools of medicine have failed to closely analyze the structural condition of joints before and after manipulation, hence they have jumped to the conclusion that all of our work was of that kind called "bone setting" for want of a better descriptive term.  This appellation, "bone setting," is a popular one, first used in England to describe the work of individuals, usually uneducated, who treated patients by manipulation of joints, which they said were out.  Quick forceful movements in the direction of normal joint actions usually resulted in a "popping" sound.  When this occurred the "bone setter" considered his work accomplished.

    Historical Reference. - Aside from adhesions the conditions which we find limiting the  movements of joints are subluxations.  Wharton P. Hood, M.D., M.R.C.S., furnished the Lancet a description of what was commonly called "bone setting." His articles were published in that journal March and April, 1871.  The articles were published in book form the same year, entitled "On Bone Setting (So-Called) and Its Relation to the Treatment of joints Crippled by Injury, Rheumatism, Inflammation, Etc." Dr. Hood made close observations of the work of a "bone setter" - Mr.  Hutton.  This gentleman sought to teach Dr. Hood his art, as a matter of gratitude for professional attention given him by Dr. Peter Hood.  In the pages of this book I find a clear, concise exposition of the bone setter's art, together with a record of the observations of the author, who has the advantage of excellent training in the medical arts.  There is no doubt in my mind as to the similarity existing between the conditions which were recognized by so-called "bone setters" and those who have formed the basis for the successful advancement of osteopathy.  The difference lies principally in the educational qualifications.  Dr. Hood notes that the manipulations were made without any knowledge of anatomy and physiology, but were nevertheless astonishingly successful, and he calls attention to the fact that much greater success, with less probability of injury, ought to result from these manipulations, when the true pathology of the joint is understood; i. e., when the operator is in fact a trained surgeon, thoroughly versed in the details of anatomy.  Dr. Hood evidently did not understand the conditions which we recognize as subluxations of the ribs and vertebrae, although he came very near to it, as you will observe hereafter.  His attention was principally fixed on the conditions following greater or lesser degrees of joint inflammation, resulting in intra-articular adhesions or extra-articular contractions.  In the case of adhesions, breaking them causes a sound which can not be repeated, but subluxations may occur repeatedly in the same joint, each reduction causing a sound.

    Tarsal and Carpal Subluxations. - In Dr. Hood's chapter on pathology, I find the following: "Subluxations of tarsal and carpal bones must occur, I think, in a considerable number of instances.  I mean by subluxations, some disturbance of the proper relations of a bone without absolute displacement, and I believe that such disturbance may be produced either by the traction of a band of adhesion about the joints, or by a twist or other direct violence." Grant the possibility of subluxation in the arthrodial joints of the carpus and tarsus, it is not improbable to conceive of them in any other joint.  As a pure example of "bone setting," one of my recent cases is apropos.  A lady stepped on some small hard object, the point of contact being just under the instep.  Sharp pain, localized on top of the instep, began at once, and was not relieved by heat or other antiphlogistic measures.  Forty-eight hours after the onset of pain, I was called to examine the foot.  Found some swelling over the instep, but palpation localized the pain in the articulation between the scaphoid and internal cuneiform.  Any attempt at local movement of this joint caused sharp pain.  The patient could not stand on the foot, on account of the pain, which was increased thereby.  Extension of the foot, with firm pressure on the upper side of the articulation, caused a very loud sound, the prominence of the scaphoid was not so apparent, and the patient could put her weight on the foot immediately. This was a case of tarsal subluxation.  If the same degree of displacement had existed in a vertebral articulation, the effect on circulation in the nerve centers of the cord might have caused very widespread symptoms.

    The subluxations treated by "bone setters" have usually been those which occasioned pain in the joint.  The osteopath does not depend upon pain as a symptom of subluxation, but makes palpation the true guide.

    Enarthrodial and Arthrodial Joints. - When the head of the femur is forced out of the ascetabulum, there is more or less tearing of ligaments, with consequent inflammation.  Replacement of the head is not accomplished without a distinct sound.  The sound is considered as audible evidence of successful operation.  The same is true of the shoulder joint.  The great range of movement in these joints necessarily requires lax ligaments, therefore great separation of the joint surfaces is possible.  The arthrodial joints, in all parts of the body, are constructed on a different principle.  The range of movement is not great in them, and their ligaments are comparatively short.  The form of the body surfaces of the arthrodial joints does not limit motion, as in the case of enarthrodial joints.

    Replacement of the head of the femur or humerus requires it to move over a ridge of bone or cartilage, and when it sinks suddenly into its proper place, a sound is heard.  Probably the sound which accompanies the reduction of a subluxation arthrodial joint, can be explained by the sudden readjustment of joint surfaces, even though there is no ridge of bone or cartilage to glide over.  It is hardly probable that a subluxated joint has its surfaces smoothly, though in a limited area, opposed to each other.  Forcing a greater area of contact corrects the unevenly opposed surfaces.

    Slow vs. Quick Reduction of a Subluxation. - A subluxation may be reduced slowly, and in such an instance no sound is heard.  Quick, sharp force is required to overcome the periarticular tension which will result in sudden replacement with sound.

    Bone Setters' Phrases. - The use of the statement by some osteopaths that a "joint is out" or a "bone is out" is merely the direct appropriation of the "bone setter's" pet phrase.  The use of the phrase "There, it's in," or some similar one, when the sound of the reduction is heard, is also an appropriation from the same source.  These phrases are unscientific, and should not be used by any one who pretends to understand the true pathology of the condition he is treating.  In the case of sound due to the breaking of adhesions, we could not truly say a "bone is out," nor in the case of subluxation is it right to describe it thus.  If it is adhesion, call it so, and if a subluxation, describe it carefully.  In this way definite knowledge of joint conditions will be gathered.

    Differences of Opinion. - There is some difference of opinion between osteopaths as to whether a subluxation must give forth a sound when properly reduced.  Discussion of the subject thus far have not settled it.  It seems that the statement made previously in this chapter, that slow reduction of a subluxation by relaxing movements will not cause a sound, but forceful and sudden relaxation will do so, about covers the facts.  We know that subluxations are reduced by both methods, with satisfactory results.  Elsewhere we have called attention to the treatment of subluxations.  For comparative purposes, and that the student may know what was understood concerning the manipulative treatment of the spinal column previous to the advent of osteopathy, we quote a portion of Dr. Hood's chapter on "Affections of the Spine."

    "Affections of the Spine," Dr. Hood. - "I fear it must be admitted that the great importance of the spinal cord, and the gravity of its diseases, have rather tended to make professional men overlook the osseous and ligamentous case by which it is enclosed, and which is liable to all the maladies that befall bones and ligaments elsewhere.  The quack, on the other hand, who probably never heard of the spinal cord, recognizes the presence of structures with which he is familiar, and deals with them as he does in other situations.  The result is much the same as in the hip joint.  The quack every now and then cures conditions which the authorized practitioner had regarded with a sort of reverence because they were "spinal"; and he every now and then kills a patient because this reverence did not exist for his protection.  If the profession generally would so study the diseases of the spinal cord as to rescue them from specialists, the first step would be taken towards rescuing the disease of the vertebral column from quacks.

    "Crick in the Back." - "However, the matter may be explained, it is quite certain that many people now resort to bone setters, complaining of a "crick" or pain or weakness in the back, usually consequent upon some injury or undue exertion, and that these applicants are cured by movements of flexion and extension, coupled with pressure upon any painful spot.

    Manipulation of the Neck. - In a few cases Mr. Hutton was consulted on account of stiffness about the neck or cervical vertebrae, and he then was accustomed to straighten them.  His left forearm would be placed under the lowered chin of the patient, with the hand coming round to the base of the occipital bone.  The right thumb would then be placed on any painful spot on the cervical spine, and the chin suddenly elevated as much as seemed to be required.  As far as my observation extends, the instances of this kind were not bona fide examples of adhesions, bit generally such as might be attributed to slight muscular rigidity, or even to some form of imaginary malady.  The benefit gained was probably rather due to the pain of the operation and the effect produced by it upon the mind of the patient than to any actual change in the physical condition concerned.

    Manipulation of the Back. - "For the lower regions of the spine he had two methods of treatment differing in detail but not in principle.  In the first, when the painful spot was found the patient was made to get out of bed and to stand facing its side, with the front of the legs or perhaps the knees - according to the height of the patient and the bedstead - pressed against it.  She was then told to bend forward until the bed was touched by the elbows.  His left arm was then placed across the chest, and the thumb of the right hand upon the painful spot.  Firm pressure was then made with the thumb, and as soon as lie felt that he had settled himself into such a position that he could obtain the full power of the left arm, the patient was told to assume the erect posture with as much rapidity and vigor as she could command.  This movement was facilitated and expedited by the throwing up of his left arm and the opposing force of the right thumb.  As a rule there seemed to be two painful spots, answering to the upper and lower border of the affected vertebrae, so that the manoeuvre would require to be repeated.

    "In the second method the patient was seated in a chair placed a short distance from the wall, so that the feet could be firmly pressed against it.  She was told to bend forward and place her arms between her legs, with the elbows resting against the inner side of the knee; to sit firmly on the chair, and at a given signal to throw herself upright.  The operator passed his left arm under the chest, placed his right thumb on the painful spot, and, in order to obtain firm and resisting pressure, rested his elbow against the back of the chair.  The signal being given, the operator, keeping his fist clenched so as to support his thumbs and the elbow being held firm in its position, when the patient throws herself upright, resists the approach of her back to the chair and bends her head and shoulders as far backwards as possible, the position of the feet preventing any forward movement.

    Treatment of Upper Dorsal. - "These two methods are used for cases in which pain is present in the dorsal vertebrae below the eighth, or in any of the lumbar.  The treatment used for the upper dorsal and lower cervical vertebrae was to place the operator's knee against the painful spot and, with the hands placed upon the shoulders, to draw the upper part of the body as far back as possible.

    "In cases when pain was complained of in the dorsal and lumbar region and the backward movements did not afford the required relief, the patient was made to bend sideways, and a similar process was gone through as in the other manipulations.

    Comment. - "As a commentary on all this, there is manifestly little to say, except that the size of the vertebral column is such as to admit of considerable diminution without injury to the cord, and that the bones and ligaments of the column as already observed are liable to the same results of injury and to the same diseases that befall bones and ligaments elsewhere.

    Differential Diagnosis. - "The surgeon who is consulted about a case of spinal malady should first of all make sure that he is not frightened by a bugbear, and should then proceed to determine by scientific methods of examination whether or not he is in the presence of disease of the nervous centers, or of caries, abscess or other destructive change in the vertebral column.  On such points as these no man who possesses a thermometer, a microscope and a test tube has any excuse for remaining long in doubt; and if he is able to exclude the possibility of such conditions, he may then regard the spine simply as a portion of the skeleton and may deal with it accordingly.  There, as elsewhere, injury and rest, or rest and counter irritation, may produce adhesions that painfully limit movement and that may at once be broken by resolute flexion and extension.  Here, as elsewhere, partial displacement may occur and may be rectified by pressure and motion.  In the lower cervical, the dorsal and the lumbar portions of the spine the change of position of any single vertebra can only be slight enough to produce pain and stiffness, but not enough to produce visible deformity.  In the highest region, however, partial dislocations are sometimes more manifest.  The following case is quoted from the hospital report of the Medical Times and Gazette of August 5th, 1865: 'John S_______, aged 21, laborer, of St. Mary's Cray, was admitted on May 26th, 1865, under Mr. Hilton.  States that he has been ailing for the last three months; loss of appetite and general debility; has, however, followed employment.  On Sunday, May 14, he was stooping down to black his boots as they were on his feet, when suddenly he "felt a snap" in the upper and back part of his neck; he felt as if someone had struck him there.  About a quarter of an hour after he became insensible and continued so about half an hour; then he felt a stiffness and numbness at the sides and back of his head and the back of his neck, with a fullness in the throat and difficulty of swallowing.  At first he had no loss of power over his limbs, only slight pain down his right arm; some days after admission, however, he had partial loss of power in the right arm, which shortly recovered itself.  On admission he carries his head fixed, and has pain on slightest attempt to rotate, flex or extend the bead; his jaw is partially fixed, and he cannot open his mouth wide enough to admit of a finger being passed to the back of the pharynx; his voice is thick and guttural; deglutition not attended by any great uneasiness.  Complains of all symptoms before enumerated.  Externally, over the spine of the second cervical vertebra, there is a tumor hard and resisting, but tender on pressure; this is evidently formed by the undue prominence of the spine of the axis itself; the tenderness is not general, but circumscribed; the parts all around are numb.  He was put on his back on a hard bed, his head was slightly elevated and a small sand bag was placed beneath the projecting spine, and the whole head maintained in a fixed position by larger sandbags.  He was ordered pulv.  Dov. gr.  V; hydr. c. creta; gr. iij., bis die.  This was continued for about ten days, when his gums became affected slightly, and it was then omitted.  Marked improvement has taken place in his general appearance and more particularly in his special symptoms.  He continued until July 3, gradually and steadily improving.  He then had acute rheumatic inflammation of the right knee and elbow joint, followed in a day or two by a similar state in the left knee joint.  There was no evidence of a pyaemic state.  The joints were blistered; he has been treated with pot. nitr. and lemon juice and is now fast recovering.  The tenderness and all the symptoms have disappeared, the projection still remaining, and he expresses himself much relieved by the continued rest in bed.'

    Size of the Vertebral Canal. - "Mr. Hilton, in remarking on this case, observed that it had been demonstrated that the area of the vertebral canal might be diminished by one-third, provided that the diminution was slowly effected, without giving rise to any alarming or indeed marked symptoms of compression of the cord.

    Conservative vs.  Radical Treatment. - "Now, there can be no doubt that most surgeons would agree that Mr. Hilton exercised a sound discretion in simply placing this man in conditions favorable to recovery, or in keeping him at rest until the axis was fixed in its new position and the spinal cord accustomed to the change in its relations.  There call be little doubt that Mr. Hutton would have made thumb pressure on the prominent spine while he sharply raised the head.  The probability is that he would by this manoeuvre have cured his patient; the possibility is that he might have killed him.  This sort of 'make a spoon or spoil a horn' practice we may contentedly leave to quacks, and without risking reputation in doubtful cases.  I think we may find a considerable number which are not doubtful, in which skilled observation may exclude all elements of danger, and in which the rectification of displacement or the rupture of adhesions will be certainly followed by the most favorable results.  For the discovery of these cases no settled rules can be laid down, since they can only be known by negations - by the absence of the symptoms that would give warning of danger.  The diagnosis must be made in each instance for itself, and in each must depend upon the sagacity and skill of the practitioner."