H. K. LEWIS, 136 GowcR Str::et. DISEASE IN BONE AND ITS DETECTION BY THE X-RAYS MACMILLAN AND CO., Limited LONDON . BOMBAY . CALCUTTA MliLBOURNE THK MACMILLAN COMPANY NEW YORK . BOSTON . CHICAGO ATLANTA . SAN FRANCISCO THE MACMILLAN CO. OF CANADA, Ltd. TORONTO DISEASE IN BONE yind its T)etection by the X-I^ays BY EDWARD W. H. ^SHENTON jM.K.C.S., eng., I..K.C.]'., LOND., SEN. SUKG. RADIOGRAl'HER, guy's hospital, iriTH ILLUSTRATIONS MACMILLAN AND CO., LIMITED ST. MARTIN'S STREET, LONDON 1 91 1 1^3 RiCHAKU Clav and Sons, Limited, BREAD STREET H11.L, E-C, AN'1> BUNGAY, SUFFOLK. PREFACE This small work constitutes an attempt to record facts which radiographic experience, extending over some fourteen years, has made me regard as funda- mental in diagnosis. They are facts which are not generally known, or I venture to think that surgeons would make more use of the X-rays, and not merely relegate them to the detection of coarse and obvious lesions. So many diseases, clinically alike, are radio- graphically different — as instances, (i) Tubercle and osteo-arthritis, (2) Malignant disease and chronic inflammatory trouble in the shafts of long bones. Several examples have come to my notice in which mistakes made in these conditions might have been avoided by the skilful use of the X-rays. I would lay emphasis on the word " skilful," for the prevalent method of getting a patient photo- graphed with X-rays by anyone in possession of an X-ray apparatus is, in my opinion, worse than having a patient's chest examined by someone whose only qualification to ofBce is the possession of a stethoscope. The absurdity in this latter case is too apparent to need discussion, and yet, in connection with the vi PREFACE former where the diagnostic instrument involved is infinitely more complex and the initial difficulties much greater, we are seldom vouchsafed more information than that the " X-rays did not show, etc., etc." We most of us only "see the things we are taught to see," and I venture to predict that in years to come we shall marvel at the very obvious pathological conditions that we are missing to-day for want of looking for them. I would further predict that the examination for varying densities in bone will become a routine practice in surgical if not also in medical diagnosis. I have not seen attention called to the various forms of thinning which are treated of in the following pages and which accompany many chronic diseases. Among such I would put alcoholism. No doubt there are many more, and I hope to be able to add to the list at a later date ; but the difficulties are very great from a technical point of view. The vagaries of the tube ape the conditions themselves, and considering one is dealing with millionths of an atmosphere it is scarcely to be wondered at. To keep the source of A-rays steady is like balancing an egg on the edge of a sword. The equilibrium is of a most unstable nature. These remarks apply to the newer forms of A-ray apparatus, such as the " Snook," which at their best are so much better than the older type of coil and interrupter, but which involve more risk to tubes and greater skill in management. PREFACE vii In selecting radiograms I have endeavoured to obtain those which I consider typical, and such as represent the usual work of a well-equipped X-ray department, and none have been printed for their photographic excellence. Opinions differ as to what is excellence in this respect. The less an individual has studied the subject the more he favours the black and white picture. Conversely, the better informed he is the less he strives after contrast and the more value he attaches to detail and the faithful reproduction of the relative densities of the tissues he is dealing with. It would seem reasonable to suppose that those radiograms are best which most faithfully represent the conditions which are present, and to use artifice to obtain a brilliant photograph of a tubercular joint seems to me to be attempting a piece of childish self-decep- tion. This is where the layman has the advantage of the medical man because he so often takes " clearer " photographs. These facts may seem elemental, but they are apparently common know- ledge only to those who work with the rays. The illustrations in the following pages are from purely unfaked photographs, and the blocks are true reproductions of these. On account of the number of these blocks I have adopted a large type and wide margin, thereby ensuring that illustrations shall be near the passages that refer to them. It will be noticed that joint disease is rather mixed viii PREFACE up with bone disease, but my excuse is that the radiographer does not, strictly speaking, see the joint surfaces, and bases his conclusions on the adjacent bone tissue. No attempt has been made to completely cover the somewhat vast ground suggested by the title of this book, and many common conditions are con- spicuous by their absence. In some cases this is due to w^ant of sufficient evidence, in others to the fact that the ^-rays are not as suitable as other clinical methods of examination. One omission I must just mention — syphilitic disease. About this I hope, later, to be able to give some helpful notes, but at present they are not ripe for publication. I w^ould like to take this opportunity of thanking many friends who have helped me directly or in- directly in the compilation of these notes. To my colleagues, Drs. Morton and Jordan, I am in- debted for many kindnesses, and to the staft of Guy's Hospital I owe more than I can acknowledge here, but for nothing am I more grateful than their attitude towards the whole subject of J^-ray work. In my opinion it has raised radiography from a branch of photography to a branch of practical medicine. As a pioneer I might have had the rough time pioneers look for, but my way has been considerably smoothed by their generous encourage- ment. CONTENTS Introductory Remarks Inflammation in Bone Tubercular Disease . Osteo-Arthritis Growth in Bone . Osteo-Malacia . ix I LIST OF ILLUSTRATIONS I'AGE Fi,;. I. Specimen of apparently good radiogram of knee-joint, which in "reality would be useless for demonstrating any but very gross lesions. It is quite unsuitable for observing atrophic changes. Compare this with Figs. 28 and 33 3 Fig. 2.— Genu Valgum. Typical rachitic bones 7 Fig. 3. — Bad fracture in atrophic bone (probably alcoholic) .... 9 Fig. 4.— Typical example of Mr. Arbuthnot Lane's method of treating fractures surgically. The entire absence of callus is noticeable . . 12 Fig. 5. — Abnormal growth of callus round fibula 13 Fig. 6.— Chronic periostitis of tibia and fibula. Observe lines of mineral matter parallel to shafts of bones 15 Fig. 7. — Chronic periostitis of tibia. Observe line of newly-formed bone parallel to shaft on inner side 16 Fig. 8. — Simple abscess just above epiphysial line of lower end of tibia. The general definition of the surrounding bone tissue would negative tubercle 1 7 Fig. 9. — Fron view of Fig. 8 i8 Fig, 10. — Chronic osteitis. The upper portion of the bone is sclerotic and the disease is quiescent as evidenced by the great density. The lower portion shows the thinning due to the active inflammation. Midway is an abscess cavity with a sequestrum 19 Fig. II. — Small abscess cavity in shaft of tibia. Probably active and con- taining bone debris 20 Fig. 12. — Results of chronic osteitis, probably healed. Old abscess cavities and much sclerotic change causing extreme density 21 Fig. 13. — Old abscess cavity in head of humerus; disease quiescent or extinct 22 Fig. 14. — Showing usual signs of chronic osteitis. Destructive and repara- tive processes going on side by side ; spindle-shaped piece of dead bone being exfoliated shown by arrow . . . 23 Fig. 15. — Chronic osteitis and sequestrum 24 Fig, 16. — Necrosis of terminal phalanx of great toe, showing ragged appear- ance of the edges of the eroded bone 2 "; Fig, 17. — Result of acute osteo-myelitis in young bone. The ulna has dis- appeared, but a new bone is growing in the old periosteum. In the meantime the radius has grown longer than the ulna 26 Fig. 18. — Sequestrum in first phalanx of second finger .... 27 Fig. 19, — Root of tooth being eroded by unerupted tooth .... 28 Fig. 20.— Clear area indicating absorption of root of central incisor. All the front teeth are crowns fitted to stumps 28 Fig, 21. — Showing light normal area around lower unerupted wisdom . . 29 xi xii LIST OF ILLUSrUATIOXS Fig. 22.— N 22.— Normal appearance of teeth Nolo ili^ , ''A'^e m its surrounding clear area uncrupted wisdom Fic:. 23.-Active tubercle in tarsus, an early stage ' ' ' ' * ' 3' Fig. 25.— Congenital dislocation of right hip ' " • • ■ 36 '■'%t;^e^nro;?xtinS °f -gSest's disease :' ''"•^^;;;^S:"^^l^S^^,^--,^^^7en se^ond'and* third lumbar the condition to be cured ^^"^"y °f t'^e bone conclusively proves Fig. 2S.-A normal hip joint showing the diagnostic line ^ " ' Fig. 29.— Rheumatoid arthritis in active stacrp Ar^f„ ,1, 1 • .' ning and the emphasising of tlfe ca^cello^s tissue ^'^^^'^^^--^^--l- ^hin Fig. 30.— Rheumatoid arthr-itis in active stage • • ■ • 4 difin"^;Sf °' ^h-'-'^S the- typical outlining" and" fine '"''"lippi;?'''':"'''':"''^. ^-'-'y h->'hy- ^"ch ^'^''DSen-i'^' TC^'''''"^■^ ''°"f '^^"^'^^ possibly by old fracture of patella. The change is not unlike osteo-arthritis in many respects i'lG. 34- -Atrophic changes in bone of amputation stump ^'"-^i^^:'^''':''"'', _ The hook turns away from the °[ ^'''''^ ^^"'-^ accompanied by some enlareement of' condition. The^^!Hk:"SroL-\;:^:iy'T::^ tr^'r-:^! s S: - bone IS very characteristic of exostosis . . ^'"^ Fig. 3S.-Exostosis of lower end of femur from a case of multiple exostosis " iZv Iv.vlc ^" =»PP'-^^'-^"'--^' t"'-'illy diflerent from the regular l.on) layeis seen in chronic periostitis. (Mr. Mower White's case ) !• IG. 40. -Sarcoma, front view of Fig. 39. (M,-. Mower White's case.) 37 40 41 42 46 47 51 52 53 55 5S 59 60 61 62 63 ^"^■nt!;.r''^".''°\V''-'' sai-coma of rapidgrowth diagnosed as greenstick fracture pi evious to A'-ray examination. No signs of ossification . . 66 Fig. 43— Endosteal sarcoma in child. Note the irregular spotty appearance 67 ritnnlP'fT"'"^'''"'''--';^,"'''"?^^ "^'^ rarefaction accompanied by new deposit of bone in neighbourhood of compact tissue. The bone would appear to be strong on account of the density of the mineral matte. 70 '''■nt.'rn":af boVe'blgjL'''^- ^'"""^ -h^re disease leaves off and fairly ^'''■nttm^''''^?r'^ '""f knee-joint. The lower margin of the minelal mailer '"^ " ^""^ °^ absorption of DISEASE IN BONES INTRODUCTORY REMARKS Those changes which take place in bone, whereby its condition is altered from one of health to disease, are accompanied by variations in opacity to X-rays. A decrease in density due to absorption of mineral matter is a much earlier and more quickly visible change than increase of density caused by extra deposition of mineral matter or new bony growth. From which it may be gathered that generally speaking acute bone disease is made evident by increase of transparency, and chronic disease by increase of opacity. Certain pathological conditions in bone are of course manifested by alteration of contour when examined by the X-rays, but even these are usually accompanied by changes in the opacity of the bony substance. It is therefore mainly to changes in density that one must look for help in the diagnosis of disease in bone. B 2 DISEASE IN BONES Normal Normal variations in bone density (meaninp; by variations •' o j denshy^ ^cnsity opacity to the X-rays) need careful con- sideration at the outset, for unless the observer makes himself familiar with these he may be led into much confusion. Bones increase in their density from foetal to adult life (or perhaps it would be more correct to say until the epiphyses are united), and remain constant Old age. after this. In old age the bones may appear denser, but this is mainly due to the lessened opacity of the surrounding tissues. In like manner thin people will seem to have denser bones than stout ones. Constant examination of the human subject will familiarise the observer with these normal appearances and enable him to detect the abnormal more easily. Variations Meutiou must be made of another variation in quaikyof thc apparent density, due solely to the X-ray tube. Arajs. rj.^^^^ which the vacuum is not very pro- Low nounced, technically known as low tubes, produce tubes. ,-11 11 a very black image of the bones both on screen and photographic plate. On the photograph, although the contrast between bone and back- ground is very great and the picture on this account rather attractive to the person who likes everything "very clear," it will be noticed that detail is mostly missing ; the effect is more that of a silhouette than a photograph (Fig. i). High Tubes of the opposite variety, i.e., the high tubes, those in which the residual gas has been INTRODUCTORY REMARKS 3 reduced to a minimum compatible with the passing of an electric current (N.B. — A perfect vacuum is impenetrable by electricity), give a Img. I.— Specimen of apparently good radiogram of knee-joint, which in reality would be useless for demonstrating any but very gross lesions. It is quite un- suitable for observing atrophic changes. Compare this with Figs. 28 and 33. faint grey image upon screen and plate. The v^ant of contrast betv^een background and bone makes the picture appear wQzk upon casual examination, but close observation w^ill show a vast B 2 4 DISEASE IN BONES fund of detail which may be of the utmost value in detecting disease. Generally speaking, a tube inclined to be high will be of more value than one of the opposite variety, but it is the part of the radiographer to suit his tube to his patient, and the tube will therefore hereafter be considered as a fixed quantity in discussing the X-rays in relation to bone disease. Import- Before leaving the technique there is one other SmTting fundamental matter to be mentioned. If an pktufe. unshielded tube is used for screening or radio- graphing, a much larger picture is produced, always supposing the size of the plate to be unlimited. Thus it is quite possible to get a leg showing knee ^ and ankle joint on one photograph, but this is only done at the expense of definition. The Z-rays, being rapidly divergent, must of necessity distort an image as it approaches the margins of the plate ; therefore in the above case both knee and ankle will be distorted. This should be borne in mind when attempt is made to get both hips upon one plate. The best rays are wasted in the middle of the plate, and it is usually much better to take two small plates so arranged that the centres of the illumination fall about the position of the Mpon- acetabula. Then again an unshielded tube, like ^u^^"' an unstopped photographic lens, is the cause of tt"'"" much distortion and fogging, and the use of a diaphragm as small as the subject will allow is advisable in every case. INTRODUCTORY REMARKS 5 If it is essential to take a large plate, that is, get a large portion of the body into one picture, this is best done by increasing the distance of tube from plate and still using the diaphragm. Such a method makes exposure very long unless apparatus such as the " Snook " is available. It should be a fairly easy matter for anyone acquainted with X-iay appearances of bone to recognise a departure from the normal. In the ^^.^j^^^^- investigation of bone disease I would lay gi'^^ter p^o^to-^ stress upon the advisability of X-ray photography as compared with screening than in any other branch of X-ray diagnosis. The roughness of the fluorescent screen, which seldom presents any hindrance to diagnostic work in a general way, may do so in the case of bone substance by J^efFectually obliterating the definition of the cancellous tissue. The photographic film is much better suited to this work on account of its fine grain. The screen, however, is of paramount import- Use of ^ screen. ance during the taking of the radiogram, to enable the radiographer to select the correct view and adjust the vacuum of his tube. Passing on to the subject of abnormal variation Precursors r . . . . . . °^ disease of density in bone, it will be necessary to consider ^hich ■' - affect conditions which, not being actually pathological, are yet often precursors or concomitants of disease. Malnutrition in the human subject is accom- 6 DISEASE IN BONES panied by atrophic changes in bone, and these are evidenced by increase in transparency to the Rontgen Rays. . Malnutrition beine more rife amone the lower nutrition. classestnan the well-to-do, it follows that hospital patients very frequently show this atrophic change, and their bones are more difficult to discern than those of the well-nurtured individual, and it is notable how much more difficult it often is to distinguish the outlines of a fracture in such a case when much extravasation of blood at the seat of fracture has increased the X-ray density of the surrounding tissues. This malnutrition is well marked, as would be expected, in many cases of rickets, but as the patient recovers in this disease Kachitis. the mineral matter is reinstated, and a rachitic deformity therefore is not invariably accompanied by a want of density. As a diagnostic factor this thinning of the mineral matter is not of much value in rickets compared with such easily ascer- tained facts as exaggeration in the normal curves of the long bones, the secondary curves and enlarge- ments at the line of junction of diaphysis and epiphysis. However, as a guide to the progress of a case of rachitis the rays may be helpfully used for observing variations of density (Fig. 2). Anttmia. ^u^iia, froui any cause of prolonged diiration, will affisct the transparency of the bones as will any disease in which malnutrition of the body generally is a prominent feature. An interesting and per- INTRODUCTORY REMARKS 7 haps unlooked for cause of loss of X-ray density is found in the case of rest or disuse of the bones of the limbs. This is a matter of common observation Fig. 2. — Genu Valgum. Typical rachitic bones. in any X-ray clinique. A bone set at rest Bones at atter tracture is a good example of this condi- tion. A few days are sufficient to bring about a degree of absorption of mineral matter capable of 8 DISEASE IN BONES Mal- union causing atrophic change. Alropliic change in alco- holism. Testing bone before operation. demonstration. I am unable to say that treatment of fracture by massage or hyperasmia has any influence upon this appearance, but would expect to find that atrophic changes were less marked if not entirely absent. Cases in which jjnion^of a fracturejias not taken place show marked diminution indensity — that is, when they have arrived at the stage at which efforts at repair have been discontinued. Natur- ally, previous to this, while an excess of callus is being thrown out in a vain endeavour to accomplish fixation of the fragments, an increase of density may be visible merely from the excess of bony tissues about the seat of the fracture. A fractured femur which had resisted all the efforts of Nature and the surgeon to become united showed this thinning to such an extent that the bone was scarcely visible in the radiogram. A^v^ri£ty_of_th^^ in an X-ray sense is t£_b£j9uadJii__die_ca^^ It is a common occurrence to see in the bones of these people a uniform atrophic appearance. Fractures in these bones are disastrous in their magnitude, being accompanied by much com- minution and crumbling (Fig. 3). They also are slow to unite and unfit for operative measures. I cannot help thinking in this connection that before bone operations the surgeon would be well advised to have the quality of the bone tested in this way. Fig. 3. — Bad fraclure in atrophic bone (probaljly alcoholic). 9 10 DISEASE IN BONES Callus. The subject of callus formation may be fittingly considered here. There is much variation in the X-ray appear- ance of callus, and as callus is only made visible by the deposition of mineral matter in its substance, these variations are mainly due to some abnormality in the manner of this deposition. It is a most fortunate fact that early callus is entirely transparent to the Z-rays ; otherwise we should not be able to judge the nature and extent of a bony lesion except just after its occurrence. As it is, for many weeks we see the exact outline of a fracture, and sometimes the deposit of mineral matter is delayed for months. Average It would be difficult to fix au averap-e time at time of _ appear- which callus becomes visible to A-ravs : perhaps ance of J ' r i callus. three to eight weeks is the normal fluctuation. Occasionally abnormal formation of callus is met with ; for example, in connection with an un- united fracture a great superabundance of callus may be present, evidently an effort on the part of Nature to obtain the desired fixation of fragments at any price. A small, clean fracture unaccompanied by displacement conversely will show a minimum of callus, and whatever is formed is quickly absorbed as union is effected. The more nearly the fractured bone is restored to its original shape and the more complete the fixation of this position the less callus will be formed, and the less mineralised will INTRODUCTORY REMARKS 11 this callus be. In fracture successfully treated by open operation, where perfect position and fixation has been accomplished, it is unusual to get any Jt-ray evidence of callus. For many years I have had the opportunity of examining nearly all the cases of fracture treated surgically by Mr. Arbuthnot Mr. Lane's ■' ■' cases of Lane and the entire absence of callus is a constant surgically ' treated feature. In cases of old fracture and bad com- fractures, pound fractures callus is usually evident, but in very much smaller quantity than when treated by other methods. It would seem reasonable to suppose that the rapid convalescence and restora- tion to complete mechanical activity which is so ' noticeable in these cases is due partly to the elimination of energy expenditure necessary for the formation and mineralisation of large masses of callus ; and to the absence of interference of soft parts around the seat of fracture due to the pressure of a large unaccommodating mass of bony material. An example which Mr. Arbuthnot Lane has kindly allowed me to reproduce will here illustrate the absence of callus in a typical case (Fig- 4)- A curious abnormality in callus formation is Abnormal Cell Ills shown in Fig. 5, and the explanation is not apparent. I have seen such a condition before but very rarely. The curious arrangement of the mineral deposits is noticeable and the history of definite fracture is missing. Whether the Flc. 4.— Typical example of Mr. Aibuthnot Lane's method of treating fractures surgically. The entire absence of callus is noticeable. 12 INTllODl'CTORV REJSIARKS 13 fracture was devoid of clinical signs and the patient continued to use these bones despite the injury, and thus an abnormal callus was caused to form, I Fu;. 5. — Abnormal growth of callus round fibula. cannot say, but were this the case the constant working of the broken ends may have had some- thing to do with the unusual appearance. INFLAMMATION IN BONE A CHRONIC inflammation in an early stage — one of a few weeks' duration unaccompanied by abscess formation — will rarely give any X-ray indications. At most a thinning or absorption of mineral matter is noticeable. Early In the case of an early chronic periostitis it is periostitis. ' , , , not uncommon tor the X-ray appearances_tq _be- normal, while clinically the bone is much enlarged. In a few weeks this thickening will becorne visible as the mineral matter is deposited. Osteitis being generally accompanied by more or less periostitis, may therefore give its first evidence by the mineralisation of the swollen periosteum. Periostitis. Looking along the outline of the bone, this newly deposited mineral matter may be seen usually in lines running parallel with, but not touching, the shaft of the bone. Presumably there are cases of inflamed bone which quickly subside and leave no trace, to the X-rays, but experience suggests such cases are rare. For example, a bone that has been struck suflficiently to cause a tender 14 INFLAMATION IN BONE 15 spot lasting a week, yet not cracked or struc- turally damaged, may in a few weeks exhibit I; I B Mbs»>£aaiiafcat...iwKaifc ■ liifta^Yia^ifa^ j Fig. 6.— Chronic periostitis of tibia and fibula. Observe lines of mineral matter parallel to shafts of bones. layers of mineral matter in the periosteum covering the part which is absorbed again in a few more weeks. Such thickening and mineralisation of Fig. 8.— Simple abscess just above epiphysial line of lower end of tibia. The general definition of the surrounding bone tissue would negative tubercle. 18 DISEASE IN BONES the periosteum over a bruised bone may suggest the callus of a fracture and that some fissure has been overlooked. It can usually be difi^erentiated Fig. 9.— Front view of Fig. 8. Linear tVom callus by the linear arrangement of the bony mentof laycrs as opposed to the spotty distribution or the newly- . formed boue salts in the latter (Figs. 6 and 7). Linear bone salts. ^^^-T": — i marks parallel with the shaft of a bone w^hich presents clinically ^n0^tKer__si^n^^th^^ Fig. io. — Chronic osteitis. The upper portion of the bone is sclerotic and the disease is quiescent as evidenced by the great density. The lower portion shows the thinning due to the active inflammation. Midway is an abscess cavity with a sequestrum. 19 C 2 Fig. II.— Small abscess cavily in shaft of lihia. Probably active and containing bone debris. 20 INFLAMMATION IN BONE 21 size, ar£_stroiig43remir^ inflamma- tion of some duration. Such inflammation may have several causes, but as a Jact v^hich con- clusively puts growth of a malignantnatufe^ouTof Fjg. 1 2. —Results of chronic osteitis, proljably healed. Old abscess cavities and much sclerotic change causing extreme density. courtjl isjiighly^jmpor^aiit, One has in mind three occasions v^hen this simple observation determined the diagnoses of three patients with enlarged shafts to their femurs, each of whom was supposed to be the victim of INFLAMMATION IN BONE 23 malignant disease. In one there was a definite history of traumatism — a kick on the thigh, but in the other two cases the cause of trouble was more obscure. It is not always so simple a matter to Fig. 14.— Showing usual signs of chronic osteitis. Destructive and reparative processes going on side by side ; spindle- shaped piece of dead bone being exfoliated shown by arrow. make a differential diagnosis between infiamma- Differen- tory and malignant condition as the case of which gnosiTof Figs. 36, 37, and 38 are the illustrations will 'nflamma- 1 1 lion. prove in the chapter on growth in bone. •24 DISEASE IN BONES Later Subsequently the subject of bone inflamed bone by other than simple causes will be dealt with, inflamma- tion, but for the present it will be better to follow Fig. 15.— Chronic osteitis and .sequestrum. up the X-ray appearances of the later stages of bone inflammation. Necrosis and abscess formation may with INFLAISIMATION IN BONE 25 advantage be considered here (Figs. 8, 9, 10, 11, I2S 13, 14, ^7 ■^^'"'^^ ''^)- The longer an inflammatory process proceeds the more easily may the thinning of the mineral Fig. 16. — Necrosis of terminal phalanx of great toe, showing ragged appearance of the edges of the eroded bone. matter and the excavations be recognised. Irregu- lar hollows with ragged outlines are the rule in an acute stage, the bone disappearing in much the same way as a lump of sugar dissolves IG. 17. — Resull of acute osteo-myelitis in young bone. The ulna has disappeared, but a new bone is growing in the old periosteum. In the meantime the radius has grown longer than the ulna. 26 INFI.AMMATION IN BONE 27 (Fig. 1 6). The cavities forming at this stage, being filled with bone debris and mineral matter dissolved from the walls, are not so obvious or easily recognised as if they were filled with air or even new growth of a soft nature, or a simple fluid ; hence one must look very carefully for them (Fig. 1 1). In one's experience sequestra are Sequestm. not so frequently found, or at any rate so obvious as would be supposed. Several examples are, how- ever, shown (Figs. lo, 14, 15 and i8). 28 The inflammatory process may proceed to com- plete destruction of the bone and mere pulpiness remain, which to the rays will show as a greyish mass with little crumbs of dark material scattered .through — particles of disintegrated bone. This appearance is rather rare in simple inflammatory Fig. 19. — Root of looih bcinp; eroded hy un- erupled tooth B. Fig. 20. — Clear area indicating absorption of root of cen- tral incisor. All the front teeth are crowns fitted to stumps. Resolution of inflam- mation. Sclerotic changes. condition, and is mostly seen in the chronic destructive process of tubercle. In the event of an acute, subacute, or chronic inflammatory process resolving, the changes in effect are slow but sure to the rays. There is a gradual clearing of the image from the absorption of fluids, a general tendency for the bone to become more opaque from the redistribution of mineral matter, gradual intensification of the bone shadow (evidently sclerotic changes and a de- positing of extra bony material where the INFLAMMATION IN BONE 29 mechanical strains of the linib demand support). A bone recovering from a severe inflammatory disorder will therefore show many dark lines and Fig. 21. — Showing light normal area around lower unerupted wisdom. formation in the periosteum will accompany this state of affairs and add to the irregularity of the picture (Fig. 12.) Old cavities will be easily recog- nisable, as those are very slow to get filled with X-ray opaque material, and one has seen such cavities many years after recovery (Fig. 13). 30 DISEASE IN BONES Where resolution has been delayed, or chronic suppuration has supervened on an acute osteitis, sclerotic changes may be seen, accompanied by disintegration of other portions of the bone, or one cavity may continue to discharge pus while surrounding portions of the bone show signs of Injection rccovcry (Fig 14). Occasionally in such cases of bismuth . ....... into bone the cavity is injected with some X-ray opaque cavities. . 1 " 1 • material such as bismuth in emulsion. This method is one that Mr. Charters Symonds uses with much success. The bismuth emulsion is injected into the cavity with a syringe, and under slight pressure finds its way into all the ramifica- tions of the abscess and the extent of the cavity is thus very satisfactorily shown. Dental Whilst discussiug the radiographic appearances tions. of inflammatory conditions of bone, special remark should be made of dental conditions. The carious tooth will of course give its characteristic shadow to the rays, but the dental mirror is obviously more satisfactory for diagnostic purposes. However, there is often much conjecture as to the health or otherwise of the portion of a tooth which cannot Abscess be seen by ordinary methods. A simple example at root. 1 r 1 '-r-