Metamorphosis of the joints of the sternum in relation to age changes in other bones.код для вставкиСкачать
METARIORPHOSIS O F THE J O I N T S O F THE STERNUM I N RELATION TO AGE CHAKGES I N O T H E R BOKES T. D. STEWART Dicision of Physical Anthropology, C. S . National Museiivi FOUR FIGURES Through his work on the pnbic symphysis, Todd (’20) established the concept that “certaiii bone areas adjacent to joints show definite sequence of modification strictly associated with age” (p. 287). Speaking of the symphysis specifically, he stated that “from the eighteenth year onward, the changes undergone by the pubis are largely if not entirely a metaniorphosis aiid not an actual growth” (p. 325). Unfortunately, however, he did not pursue this subject much beyond the s p p h y s i s . at least as regards the lafc-maturing joints of the postcranial skeleton. Indeed, his summary of the possibilities of finding skeletal age markers, which appears in the introduction to his study of the symphysis (’20, pp. 287-288), indicates that he regarded similar studies of certain other joints, aiid especially those of the sternum, as rather unpromising. P a r t of this statement is worth quoting, nerertl~eless, because it summarizes joint mctamorpliosis in a masterly way : I n the main this group [of joints yielding a sequence of modification associated with age] consists of amphiarthroses, namely the syniphysis pubis, the intercentral joints of the vertebral column, and the manubrio-gladiolar articulation. But to these must also be added the sterno-clavicnlar, sa cro-iliac a n d possibly the eosto-chondral and chondro-sternal joints. The plane between the bone and the articular cartilage of these joints displays features resembling in some degree those of the diaphysoepiphysial plane, and it is upon this fact that the age changes resolve themselves. Adjacent to these joints “articular” epiph519 incoiiipletely. ci*riitic~iiIly or iiot ; i t all. Of tlie series the sterno-clt~\.icnlar area rarly reiiioves itself from consideration throng11 the firsion of tlir c1piphysih at the strrnal twtl of the clavirle with the slinft of the. bone, while the iiiannbrio-gladiolar articulation is so chrratic a s apparently t o \\-arrant no confidence. The intercentral joiiits of the rertebriil coliimn, and tlie pelvic. tirticulation areas, on tlie other. liantl, a r e niost important. E v ~ n after tlie last stragglers niriong the epiphyses. namely those of the spines tincl transverse ~)i*ocesses of tlie vertebrae, the heads of the ribs, arid the sternal end of the clavicle, have lost their identity through fiision, tlie line of iinion of the central epiphyses shows distinct intlepcndenve froin tlie rertebral body. And when the second of these also tit last, in the early thirties, fails t o register the individi~al’sage. the syniphysis pnbis still retains its role of time marker. Tndeecl, the syniphysis tells its tale tlironphout life, altliongh Icss clearly from forty years onward than a t a n earlier age. ?-ses ossify I d o not bcliclve tliat Todd intended these rcniarks to discourage others from doing reseiirch along the same lines on the joints of the sternum; I think he was only justifying his o~l’ii wurse of action by i.eportiiig a wiclel~-hel~cl belief which he had not bothered to check adequately. After all, he may have been well awarc tliat back ill 1890 Thomas Dwight, Professor of Anatoniy at Harvaid, had expressed the opinion that “the e stciwum is of little raliie a s ail index of age” (p. 532). T l ~ fact remains, however, that today, a quarter of a century after Todd studied the pubic syniphpsis, we still cannot read with any confidence the s i p s of ageing displayed in tlie joints of the sternum. Also, the need has existed all this time for other criteria by wliich to assess the aqi of skeletons which have damaged or missing pelves. Further accounting for the long-stmiding neglect of age changes in the strrnum is iIniiccessai’y liere. T will say simply that ~vlienrecently I ~ v a soffered the opportunity to observe (at a future date) age cliaiiges in skeletoiis of fully identified yonng adult males, I decided to csteiid my observations to the unstudied joints rneiitioned by Todd in tlic ahore quotation. This clecisioii nccessitatecl a11 exaniinatioii of tlie features ill question so a s to determine what is significniit f o r iwording AGE CHANGES I N THE STERNUM 521 purposes. Having a t liaiicl oiily skeletoiis froni archcological sources, I could evaluate the observed sequence of hone modification in each joint area only in terms of k n o w i age changes in other parts of the same skeletons, particularly tooth eruption, cpipliyseal union, sj-mphyseal metamorphosis arid suture closure. Sirice st17dy of the sternum has proved to be surprisingly rewarding, and since all ohsei*vations of this nature are useful in skeletal identifications, I feel that my findings on this bone are worth reporting in advance of the opportunity f o r smuring more exact dating. (See acldendnrn, p. 528.) ANATONY O F THE STERNAL JOISTS The sternum is uiiique in the number aiid types of its articulations. In addition to tlic mannbriogladiolar or superior intersternal joint, which in most cases is a synchondrosis (fig. l),‘there are a pair of stcrnoclavicular joints (type: diarthrosis), and usually 7 pairs of chondrosternal joints (types : first pair a r c syncliondroses ; all others diarthroses). The inferior intersternal joint, that between the corpus of the steriium and the xiphoid process, may be ignored for present purposes. This makes a total of 17 joint areas the metamorphosis of which may be expected to provide age markers. I n this coiiiiectioii it is noteworthy that on each side the joints for the clavicle and first rib, which differ in type (see above), are contiguous, whereas the joint f o r the second rib is located a t the junction of the inanuhrium and corpus and hence in close relationship with the superior intersternal joint (again 2 joints of different type i n juxtaposition). Such relationships require that these two joint complexes be considered as units from the standpoint of niodification with age. In addition, since the superior elements of the corpus may not fuse until early in the third decade, and the joint for the third r i l ~is located a t the * Gray’s :iliatomy cites Rivitigton siid Maisoiineuve as authorities f o r thc stntonient thiit this joint is diarthrodial in one-third or more of adults, being formed in these eases perhaps by absorption from the original sprhondrodinl (ampliiarthrodial) form. 522 T. U. STEU’AitT line of union, the metamorphosis of the third chondrosternal joint probably reflects the local rate of ossification. Todd was correct in stating (see above quotation) that “The plane between the bone and the articular cartilage of these joints displays features resembling in some degree those of the diaphyso-epiphyseul plane ; and it is upon this fact that the age __ Costo-claviculnr Ular Fig. 1 Diagrani of tlie upper riid of tlie steriinni showing the different types of joints. Note that in the case of the first rill (but iiot tlie second or others) bone is joined to bone by cartilage, without the intervention of a joint earity. Apparently the sanir is true in most caws for the superior iutcrsternal joint, although the diagram i s not clear on this point. (After Cuniiinglinni’s fig. 300). changes resolve themselves.” So f a r as I can discover, all textbooks of aiiatomy fail to mention epiphyses in descriptions of the ossification of the sternum. Probably this is due to the delicacy a i d prompt union of the epipliyseal plates in the areas of the steriial joints. Naturally, unuriited plates would be lost in skeletal mslccration and hence would not be seen. On the other hand, the possibility exists that these plates sometinics are reduced i l l size o r not formed at all, and AGE CHANGES IK THE STEKRI!JI 523 this view is supported by such findings a t the stel-nal end of the clavicle (Todd and d’Errico, ’28). DESCRIPTION OF TIIE SEQUENCE O F MODIFICATIOR’ Although the foregoing anatomical details help explain the changes observable in the sternum, anyone attempting to assess age from this bone should first study a series of irnmature specimens in order to appreciate the range of variation in size, shape and details of joint arrangement. Trainiag the eye to distinguish between random variation and progressive modification is essential to correct interpretation of age. I n the description of the modification sequence that follows, a few typical specimens have been selected from the many examined to tell the story. Here, then, variability must be referred to as something to be taken into account, and not singl!.lcd out for special treatment. First, let us look a t a few sterna from in front and arranged according to physiological growth stages (plate 1). Note that in only two of the 6 bones displayed is the corpus united into a single piece of bone. I n the two that are thus united the epiphyses of the long bones a r e also united, and hence these individuals may be regarded a s being past the age of 20 years. The other 4 bones, being from younger individuals, show various stages of fusion involving different numbers of elements (between 3 and 5 ) . Also, it is clear that, although the elements of the corpus a r c erratic in uniting, the top element is generally the last to fuse. On this basis alone it is often possible to distinguish skeletons of the second and third decades. Plate 1 also affords a front view of the superior intersternal joint. I n the three examples shown in plate 1, note that the contact between the manubrium and corpus widens with age. On this basis one would expect a corresponding progressive modification of the joint surfaces. Indeed, it is a general rule for such joints, as Todd was always careful to point out, that before adulthood the surfaces and borders are rounded and soft-textured ;but during the third decade angularity and hardtexture appear. Other than this reference to conformity of the 524 T. D. STEWART joint surfaces I will not h a r e much to say about the changes in tlie superioio interstel-nal joint, the reason being that most of these changes parallel others which deserve more atteiition. We turn nest to the conjoined articular areas for the clavicle and first rib at the snperolatcral angle of the manubrium, Plate 2 sliows 9 manubiia standing 011 edge so as to show the areas of particular interest and also arranged by physiological growth stages. Beginning at the left end of the upper row, note that in the first t h e e the facets for tho clavich and first rib are poorly differentiated. If 01-eover, the articular surfaces a r e dimpled or billowcd and h a r e tl matte-like finish or texture. As will be recognized by those familiar with the skeletons of a8clolescents,such an appetirancc is typical of a joint in the stage preceding epiplipseal union. So far as I can judge iio~v this stage continues here until 17 or 18 years of age. Before leaving these three specimens, I call attention to tlic lower edge of the articular area for the first rib. This edge is well clcfiiiecl in the second rind third specimens but not in the first. The distinction here is not due to age, hut represents instclad a comnioii variation. The first specimen is a n example of a bone in d i c h a t this age all of the borders, except that in tlie midline superiorly (the jugular iiotch), hare tlie appearance of developing into articular surfaces. I n such a case the facet for the first rib ultimately would develop a lower edge, but otherwise the lateral border of the bone would a l w a p reflect the appearance seen here. An unclei-standing of this coiidition makes the pictiire less confusing. N o w we turn to tlie next three bones in plate 2, that is, the last two on the top row aiid the first on the bottom row. These three specimens sliow different stages of epiphyseal union. I n the first of the t h i w , the epiphysis for the claviculai- facet is in the process of uniting. There is no iiiclication of an epiplipsis f o r the adjacent rib facet. Indeed, the latter surface still has the appearaiice of being prepared to receive a n epiphpsis. Ry contrast the seconcl specimen has iiicomplctely attached epiphp e a l plates on both surfaces, a i d on the surfaces of the coiijoined intei*stei~naland sccond choiidrosternal joints R S well. AGE C H A N G E S 1K T H E STEHNUM 525 The t1iii.d spccinieii, on the other hand, has progressed still further. Here the articular surfaces a r e completely glazed over. Yet the appearance of tlie facet f o r the first rib in this third specimen would suggrst that ail epiphysis for this area never formed and that a glaziiig of mature bone had served as a substitute. The latter process is probably of comnion occurrence a,t this site. I n any case, siiice at least two of tlie skeletons iiivolwd a r e in the stage where tlie proximal epiplij-sis of the humerus is uniting, I would judge that the stage of sternal maturation under consideration takes place around 19-20 years of age, although it may extcnd over a longer period. Before leaving the second group of three bones, I call attention to the developing enlinelice a t about the midpoint in the conjoined articular areas. As will be seen by looking ahcad in plate 2, this eminence is to develop into a sharp transverse ridge which will form tlie boundary between the two welldefined facets. Thus in due course a ridge will provide the superior edge of the facet for the first rib and the lateral edge of the facet for the clavicle. However, at the time these articular areas receive their epiphyses, or glaze over, the eminence is still rounded and incompl& ventrally. Until the vcvtral interarticular notch is filled in and the eminence is transformed iiito a transverse ridge delimiting the facets, the inanubrium cannot be said to have reached maturity. According to present indications the interarticular notch disappears, and the transverse ridge is formed, when the epiphyses of the iiiiiominate a1.c about united; in other words, early in the first half of the third decade. With these events in mind, we are ready to examine more closely the last three bones in plate 2. Thc first shows the signs of maturity just described. I n this case the epiphpsis at the stcriial end of the clavicle is uniting, which would lie before 25 pears of age according to Todd and d’Errico ( ’28). The sccoiid differs from the first mainly in haring formed a raised rim around the edges of the facets for the first and second ribs. J u s t when the rim appears is not certain, but probably it is hetween 23 and 30 years of age. Later, as the third speci- 526 T. 1). STEWART men shows, this rim 8disappcars into the bonv spurs so characteristic of hypertrophic or degenerative arthritis. Between these eveiits tlie surface of the facet for the first rib becomes more porous, owing perhaps to the fact thai it is not an arthrodial joint like its neighbors. I am iriclined to believe that this unique chondrosternal joint is among the first to show degenerative changes. I n any case, arthritic lipping p r o h ~ b l yappears here early in the fourth decade. We come now to plate 3 showing, with one exception in lateral view, both the nianubriurn and corpus from 4 individuals. The purpose of this plate is to show two things: (1) p a r t of the sequence of modificatioii ill the lower chondrosteriial joints, and ( 2 ) vtii*iationin thickness of the superior intersternal joint. The first specimen on tlie left is in the late stage of maturation already described where, in the manubriuin, the ventral interarticular notch is just disappearing. Indeed, in this case the filling-in of tlic notch seems to he taking place along with the union of cyiphyses in most of the chondrosternal facets. This probably represents one of the sequential vitriatiotis that one w ~ ~expect l d to encounter in a large series. A t least this specimen mikes it clear that all of the chondrosternal facets may have more o r less complete cpiphpseal plates present tind uniting either just before the ventral interarticular notch fills in or along with the filling in thereof. Reference was made in connection with the anatomy of the joints to the fact that the tliird costal facet may show sigiis of tlie recent fusion of the upper elements of the corpus. Although the first specimen in plate 3 scarcely demonstratcs this fact, the second and third specimens show a division of the third facet by a transverse cleft. The resemblance in the latter specimens of the third costal facet and the second costal facet (as divided by the superior intersternal joint) should be apparent. Observe, however, that the cleft in the third facet is being bridged over both dorsally and ventrally. The bridges probably a r e equivalent to the rims of the other joints. Althougli the cleft may persist into middle age, the presence and thickness of the bridges give some idea of the relative age. AGE CHANGES IN THE STERNCM 527 The fourth specimen shows the appearance of the lower costal facets around middle age and before they develop arthritic lipping. Finally, I call attention to the increased veiitrodorsal thickness of the superior intersternal joints in the second and fourth specimens. Actually, in the second specimen this joint is partly fused. As for the fourth specinicn, the manubrium has been turned so a s to expose the inferior joint surface and to show that this surface has begun to break down. The appearance suggests that here, too, is an intersternal joint on its m-ay to fusion. Although thickening of the bone does not always accompany fusion of this joint, it seems to represent bone reaction connected with joint disturbance, and hence one of the conditions leading to fusion. Regardless of the causes of synostosis in this joint, age is not a factor in the process, as Trotter (’34) has pointed out. SUNMARY I n view of the need for inforniation about age changes in the human steriiuiii, I h a r e explored the subject in a series of skeletons representing the native peoples of North America. Although, under the circumstances, it is impossible as yet to assign definite ages to developmental events, and variability in rate of development cannot be evaluated, the association of these events with datable age changes in other bones should prove useful in assessing the age of skeletons. Thus the metamorphosis of the sternal joints in very tentative terms may be outliiied as follows : I . C p t o the t i m e t h e proximal epiphysis of the Iiurnerzis is tmdi”iLg ( u p to 17’-18? y m r s ) . Component elements of the corpus sterni a r e still identifiable, although those in the inferior two-thirds may have fused. Joint surfaces here mid in the maiiubrium arc rounded, dimpled or billowed, and exhibit a matte-like surface texture. 2. Coincidelit with, m i d somewhat f o l l o u k g , the u%ioion. of the proximil epiphysis of the huinwrts (about 19-20B years). 528 T. D. STEWART Epiphyscal plates can Iw found in all staaes of uiiioii on the clavicular facets. At tbc ciid of this period epiphyseal plates a r e begiiinirig to unite on the rib facets, or failing thc formation of plates, tlie articular snifaces are begiiiiiing to glaze over. Also, in most cases, tlie superior eleriient of the corpus is fusing with the clement liest below. 3. CoiiicidmLt zcitk t h c 1 ~ w i o r jof tlic. cyipliyses for the iliac c r c s t (aid ischiirl rnirius (cihozrt 20-2.7P y w r s ) . The eminelice marking the boundary between the articular areas of the clavicle arid first rih gives way to a sharp transTerse ridge. The last step in tlic formation of this ridge is the filling-in of a ventral interarticular notch. At this time the facets for the third ribs a r usually ~ dividccl by a transverse cleft, the last remaining s i p of the recent fusion of the superior element of the corpns. 4. C'oir~cidc~nt with crntl iui incilintcly f o l l o w i q irniorb o f the o p i p h y s i s o t t h o stcriirrl (,nil of tltc rlni;irl~ fabozit 2.?-30? ?Jf flT S ) . Raised rim is formed around the articular areas of the first and second ribs arid those of tlie superior intersternal joint. By this time tlic snpcrior intersternal joint has broadened so that the articular surfaces arc rectangular. Facets for first ribs become slightly more poiwis. ('lcfts in facets for third ribs a r e being bridged across ventrally and dorsally. 5. ,Jirst bcJfore o r coiwirleat with t h e n p p c a r n w c of crrthritis in f h c 1.ertobrtrc. (cibout 3 5 yfcrrs). Hypertrophic bone spurs appear around the niargiiis of the facets for the first ribs, particularly ventrally and dorsally and nioi-e ahove tliaii below. The othc~r.rib facets develop spurs much more slom-ly. Also, there may be progressive, disorderly break-down of the joint surfaces. A 1) r ) mi ) n r Whrii this paper was sitbiiiitted f o r publication iii May, 1954, the opportimitg to piirsne thc subject further seemed unlikely to come about f o r some time. Yet (.rents took a sndden change by the latter part of the siiiiiiiier a n d I was able to go t o J a p a n in September for AGE C H A S G E S Ih- T H E STEHNUX 529 the purpose of examining the skeletal reinaiiis of American soldiers recei\7ecl in exchange from the C‘oiunlunists through Operation Glory. Accordingly, I hare reviewed and corrected the present paper in the light of this experience. Evtwtually I hope to amplify arid docuiiieiit the sequence of sternal niotiifications associated with age here merely outlined. LITERATTJBE CITED (”., AND E. B. JAMIESON(ecls.) 1937 C~uiiiiiiigliam’s Text-Rook of Anatomy. 7th ed., Oxford Unir. Press, New York. DWIGHT,THONAS 1890 Tho steruuni as an index of sex, lieiglit and age. .J. Anat. nud Physiol., 2 4 ; 5“-535. I-EIVIS, WARREN H. (eil.) 1930 (:lay’s Anatomy of the IIuinnu Body. 231d ed., Len and Febiger, Phila. TODD,T. WINGATE 1920 Age changes in the pubic bone. I. The male white pubis. A m J . Phys. Anthrop., I I I : 285-334. TODD,T. WINGATE,A X D J. D’ERRICO, J R . 1928 The c1arirul:rr epipliyes. Aui. J . Anat., 4 1 ; 25-50. TROTTER, MILDRED1934 Inridenee of synostosis between niauubriuin and body of the sternuni in Whites and Kegroes. Am. J . Phys. huthrop., X V Z Z I ; 43 9-442. BRASH,J . 364785 345357 366610 308643 31429’’ 3 i i 92 3 no. Z’.AS.N.M. Alent E~skiiiio Eskimo Koni:ig Pueblo Pucblo h’ncicil groicp O(JC murk( r Ikgiilining union of di&I eliipliysis of Iiunicrus I’roxiui:il u1ii:ir epipliysis in :id\ awed stage of i i i i i i i i i Iiegiiiiting uiiioii of proximal epipliysis of humerus T’rosimal epiphysis of huinerus uniting Epiphysis at stcriial end of clavicle utiitiug 1,ong bone cpipliyses uniitctl; w r y slight :irtliritis; proI):ild.v Iieginiiitig suture rlosiire Pkyaioloyicnl Frout view of a series of sterna selected to diow rertaiu dcre1opmcllt:tl fcaturcs cliscusscd in tlie text. Left to 1iglit: IXI’LASATIOK OF FIGUKES I’LATE 1 3 535 366610 377i06 3i4626 372815 Bottom 374625 37i923 363656 345337 32i128 IYJW Top row : no. U.S.N.M. : Ko11iag Kouiag Koiiiag Koiiiag Koiiiag Aleut Kouiag Eskimo Pueblo Racial group s ting l’rositiid epipligsis of l ~ i i u i c r i ~uui I.:pipli;vsis for sternal ond of clavicle uuitiiig Long b o w e ~ ~ i p l i ~ united; scs 110 arthritis; sottie siiturc clorure Epipliyses united ; moderate arthritis; adriiiiced suture rlosure Pcrmauent R1’ erulitctl; distal cyiplipis of liuitic~rusutiiuiitrtl Beginniug union of distal epiphpis of liunierns Epiphgsis f o r iiirdial epicoiirlylc of Iiiiiiirriis uuitiiig Brgiiiiiiiig uuioii of prorinial epipliysis of Iiuuicriis (No associated holies) Pliysiologicul age ?iiurk.rr Lateral yiew of a series of niauubria selected to show eertaiii developutental features diwusscd in the test. From left to riglit : EXPLANATION OF FIGURES PIABTE 3 3 535 308642 377902 378G91 225259 NO. U.S.N.M. Pueblo Aleut Aleut Sioux Racial group Epiphysis a t sternal end of clavicle uniting Epiphysis at sternal end of clavicle united ; no arthritis Epiphpses united; bcginning arthritis; aclvancc*d suture closure Beginning arthritis; advanced suture closure P h p o l o g i c a l age ~ n a r l r r Lateral view of 4 sterna (1 nisnubrium turned over to show the inferior articular surface) selected to show certain developnieiital features discussed in the text. S o t e the thickening of the bone a t the superior intersternal joint in two of the cases. From left to right: EXPLANATION OF FIQUKES PLATE 3 3 535 536 A M E R I C A N J O U R S - 4 L OF P H Y S I C A L ANTHROPOLOGY GENETICEFFECTOF TRRADIATION.-- There is another basic difference between irradiating Drosophila eggs and the ovaries of nonpregnant women, namely, in the reproductive cycles. The Drosophila reproduces itself in about 10 days. some 30 generations being produced within one year, although its life cycle is about 90 days. Aftcr irradiation, little time is left between generations for full recovery from its effects to take place. In contraht to secondary effects on progeny of the Drosophila, an interval of at least 20 years elapses between generations in populations of western countries. Twenty-seven years passed before a follow-up note could be made on the second “seed generation” in the case reported here. Thc grandchild appears to be normal by all pediatric standards. This is the 5th such casc rccorderl ; Raplan has encountered 4 others. The long span of tiiiie between generations obviously makes it difficult to give an absolute answer to the theoretical question of the ultimate harmful genetic efyect of irradiation on the human race. l h t the long interval of time between births of a firqt and second generation would 11-arrant the assimption that whatt!ver harmful effects may have been produced by the x-ray irradiation to the ovaries of a grandmother would have been dissipated over the years. No acquired let,hal effects on the genes have becw obserred in hundreds of babies born following this treatment for the relief of infertility and delayed menstruation. The additional reeord of 5 normal grandchildren fails to snpport the claim that low close s-ray irradiation to the ovaries and pituitary produces harmfnl (ffects in human reproduction.- I. C. Rubin. Third generation follou-up in xi-onian receiving pelvic irradiation. J. Am. Med. Assn., vol. 1.50, no. 3, Sept. 20, 1952, pp. 207-209. KURTB R 6 s T E . - After a long, and as it turned out, hopeless illness, Kurt Broste, M.D., died in Clopenhagen on the 26th of April, 1954, at the age of 52. Since 1941 he had been director of the Laboratory of Physical Anthropology of the 1Jniversity of Copenhagen. Under his leadership a series of scientific articles were issued from this institution, articles mainly dealing with the anthropology of prehistoric peoples in Scandinavia as well as in the Eskimo areas. ljnfortunately he did not live long enough to finish his IifeiTorlr, a great book on “Prehistoric N a n in Denmark” of which only the first volume has gone into print. We who are left to continue his work will do our best to keep up to his brilliant example, always remembering with gratitude his keen brain, his never failing eheerfnl encouragement and genuine interest in his pupils.- J . Balsle\- JorFensen, M.D.