Metamorphosis at the sternal rib end A new method to estimate age at death in white males.код для вставкиСкачать
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 65:147-156 (1984) Metamorphosis at the Sternal Rib End: A New Method to Estimate Age at Death in White Males M. YAQAR IQCAN, SUSAN R. LOTH, AND RONALD K . WRIGHT Department OfAnthropology, Florida Atlantic University, Boca Raton, Florida 33431 (M. Yl., S.R.L.); Broward County Medical Examiner’s Office, Ft. Lauderdale, Florida 33312 (R.K.W ) KEY WORDS Ribs, Costochondral junction, Sternal end ossification, Aging, White males ABSTRACT While the pubic symphysis and intracortical morphometry have provided successful results in estimating age a t death, other methods and sites in the skeleton are needed to improve the accuracy of age estimation. This research is a n attempt to develop a new age-determination technique by using the sternal extremity of the rib. The right fourth rib was collected at autopsy from 93 white males. The sternal extremity of each rib was analyzed in relation to the pit depth (component 0, pit shape (component II), and rim and wall configurations (component 1111, each of which was divided into six stages. Results indicated that the age a t death can be estimated from a rib within about 2 years in the second decade to about 7 years in the fifth and sixth decades of life. Pit shape and rim and wall configurations yielded better results than absolute pit depth alone. While this method has a potentially important contribution to skeletal anthropology, factors such as sex differences and biomechanical variation between individuals may affect the determination of age from the rib. Although techniques for the determination of skeletal age a t death have improved from the limited success provided by analysis of cranial sutural closure to the more reliable results obtained from symphyseal changes in the pubic bone (Stewart and Trotter, 1954; McKern and Stewart, 1957; Krogman, 1962; Acsadi and Nemeskkri, 1970) and microscopic evaluation of intracortical remodeling in the long bones (Kerley, 1970; Thompson, 1979) additional methods are still being sought. The present study is a n attempt to develop a new method to determine age from the sternal end of the rib by using a controlled sample of individuals of known sex, age, and race. This attempt to determine age from the rib was based on evidence provided by radiographic, histologic, and osteological studies. Radiographic analyses have focused mainly on mineralization of the costal cartilage and its apparent increase with age (Nishino, 1969; Semine and Damon, 1975; McCormick, 1980). Histologic studies have been primarily concerned with bone remodeling in the rib (Sed- 0 1984 ALAN R. LISS. INC. lin et al., 1963; Epker et al., 1965; Frost, 1976). These studies indicated that the medullary cavity of the rib enlarges and periosteal bone deposition continues throughout life at a faster rate than periosteal resorption. However, this process was outstripped by a n increase in endosteal resorption, resulting in the progressive thinning of the cortex of the bone (Epker et al., 1965). At the gross anatomy level, Kerley (1970) and Ubelaker (1978) have briefly alluded to age-related metamorphoses in the sternal extremity of the rib. Kerley (1970) noticed that the joint surface is billowy in adolescence, while margins are sharp and cupshaped in middle aged adults, and irregular in old age. Based on this information and our own observations, it was thus expected that the rib would show age related metamorphosis observable by gross examination of the bone. A survey of the literature and reference sources Received July 14, 1983; revised June 4, 1984; accepted June 5, 1984. 148 M.Y. ISCAN, S.R. LOTH, AND R.K. WRIGHT in forensic and physical anthropology have indicated that this part of the rib has not been analyzed in depth by direct examination (Levine, 1971; Eckert and Noguchi, 1974; Semine and Damon, 1975; McCormick, 1980; Igcan, 1983). Apart from the aforementioned studies, the sternal end of the rib has been neglected in spite of its potential suitability as a viable site for age determination from skeletal remains. MATERIALS AND METHODS To observe age-related changes, the sternal end of the right fourth rib was collected from white males autopsied a t a medical examiner's office. All adherent soft tissues, including the costal cartilage, were easily removed from the bones after the specimens had been soaked in water for several weeks, then boiled gently for 10-15 minutes. The sample consisted of 93 specimens. Only those individuals 17 years and older were included in the analysis because morphologic metamorphosis a t the sternal end of the rib were not observed until this age. Table 1 shows the frequency of specimens in each age interval. Approximately 75% of the sample were under the age of 50. Furthermore, it should be noted that the highest concentration by age was in the twenties (34%). The mean age of the sample was 38 years. A system of component analysis, analogous to that used by McKern and Stewart (19571, was developed to quantify the metamorphoses observed at the costochondral junction. Each rib was examined with special attention to three factors (components) where changes were most noticeable, i.e., pit depth, pit shape, and rim and wall configurations. Data were analyzed statistically using SPSS programs CROSSTABS, BREAKDOWN, and ONEWAY analysis of variance (Nie et al., 1975; Hull and Nie, 1981). Component I: pit depth One of the most obvious age-related changes observed is the formation and deepening of a cavity (pit) at the sternal end of the rib. The maximum depth of this pit is measured with a depth caliper calibrated to 0.1 mm. This measurement is taken where the distance between the base of the pit and the adjacent anterior or posterior wall is the greatest. The caliper is held perpendicular to the base of the pit. The cranial and caudal sides of the rib end are not used because of the presence, in some specimens, of long projections of bone. These projections are consid- TABLE 1. Age Distribution of specimens in the sample Age intervals (in vears) N 0-16 17-19 20-29 30-39 40-49 50-59 60-69 70 and over 9 7 29 12 15 8 7 6 9.7 7.5 31.2 12.9 16.1 8.6 7.5 6.5 Total 93 inn n O/n ered by many earlier researchers such as Fisher (1955)and Semine and Damon (1975) to be more closely associated with sex than age, and more recently aErmed by McCormick and Stewart (1983). Component I is divided into the following six stages (Fig. 1): 0. Flat to slightly billowy extremity with no indentation (pit) greater than 1.1 mm 1. Definite pit formation with a depth ranging from 1.1 to 2.5 mm 2. Pit depth ranging from 2.6 to 4.5 mm 3. Pit depth ranging from 4.6 to 7.0 mm 4. Pit depth ranging from 7.1 to 10.0 mm 5. Pit depth of 10.1 mm or more Component II: p i t shape Component I1 deals with changes in the shape of the pit. Initially, the pit is only a slight, amorphous indentation, which in about 1year from its first appearance, develops into a structure which is V-shaped. This V-shape is formed by the posterior and anterior walls of the rib. Over the next few years the base of the V widens to become U-shaped. As age increases the walls of the pit grow thinner forming a progressively wider U. Component I1 is divided into the following five stages (Fig. 2): 0. This stage is used for juvenile and adolescent specimens with no pit formation at the flat or billowy articular surface. 1. A shallow, amorphous indentation (pit) is now present. 2. Formation of a V-shaped pit with thick walls. 3. The pit assumes a narrow U-shape with fairly thick walls. 4. Wide U-shaped pit with thin walls. 5. The pit is still a wide U-shape, yet deeper, more brittle, and poorer in texture with some disintegration of bone. METAMORPHOSIS AT THE STERNAL RIB END Fig. 1. Component I-Pit depth. 0-stage 0. Note nearly flat, billowy surface. There is no pit formation. 1-stage 1. Pit has formed to a maximum depth of 1.6 mm. 2-stage 2. Pit depth is 3.7 mm. 3-stage 3. Pit 149 depth is 6.1 mm. 4-stage 4. Pit depth is 7.4 mm. The bony projection on the superior border of the rib is not included in the measurement. 5-stage 5. Pit depth has reached 11.1mm. 150 M.Y. ISCAN, S.R. LOTH, AND R.K. WRIGHT Fig. 2. Component 11-Pit shape. 0-stage 0. This specimen shows no pit formation at the nearly flat, billowy medial articular surface. 1-stage 1. Newly forming amorphous pit is obvious between the anterior and posterior walls. 2-stage 2. A V-shaped pit formed by the anterior and posterior walls. 3-stage 3. A narrow U-shaped pit with fairly thick walls. 4-stage 4. A wide U-shaped pit with thinning walls. 5-stage 5. A wide U-shaped pit exhibiting brittle texture, very thin walls and some disintegration of bone. METAMORPHOSIS AT THE STERNAL RIB END Fig. 3. Component ID-Rim and wall configurations. 0-stage 0. Note smooth, rounded rim and no wall formation. 1-stage 1. Rim still smooth and rounded with incipient wall formation defining the shallow pit. 2stage 2. Scalloped or slightly wavy rim forms the edge of thick, dense walls with smooth surfaces. 3-stage 3. Scallops are disappearing and the rim is becoming 151 more irregular. Walls are thinning but still fairly dense and smooth. 4-stage 4. Rim is becoming sharper and increasingly irregular. Walls are thinner and less dense with noticeable deterioration in texture. 5-stage 5. Rim is very sharp and highly irregular with frequent bony projections. Walls are very thin, brittle and porotic with deteriorating texture. 152 M.Y. ISCAN,S.R. LOTH, AND R.K. WRIGHT Component IIE rim and wall configurations Component I11 analyzes changes in the configurations of the rim and walls of the pit. The rim starts out as a smooth, regular border around the pit that rapidly assumes a scalloped but still fairly regular shape. Eventually, with advancing age the rim and walls become increasingly irregular, thin and sharp. Component I11 is separated into the following six stages (Fig. 3): 0. The 0 designation is for those specimens with a smooth regular rim and no wall formation. 1. Beginning walls with a thick, smooth regular rim. 2. Definitely visible walls that are thick and smooth with a scalloped or slightly wavy rim. 3. A transitional stage between the regularity in stage 2 and the irregularity in stage 4.The scalloped edges are disappearing and the walls are thinning, yet the walls remain fairly sturdy without significant deterioration in the texture of the bone. 4. The rim is becoming sharper and increasingly irregular with more frequent bony projections often most pronounced at the cranial and caudal margins of the rib. The walls show further thinning and are less sturdy with noticeable deterioration in texture. 5. The texture shows extreme friability and porosity. The rim is very sharp, brittle and highly irregular with long bony projections. Occasionally, as the depth of the pit increases, windows are formed in areas where the walls are not complete. RESULTS Table 2 contains the descriptive statistics and 95% confidence interval of the mean for the components, individually and in toto. Based on the five stages considered in the analysis of component I (pit depth), the mean age increased by 10 years or more from stage 1 through stage 4. Pit depth alone did not prove to be a good indicator of age after the fifth decade. The range of the 95% confidence interval showed a gradual increase in stages 1through 3 and a marked increase in stages 4 and 5, representing individuals over 50. Table 2 also shows the same analyses of components I1 (pit shape) and I11 (rim and wall configurations). In both of these components, the mean age rose 5 to 8 years in stages 1 through 3, then increased to over a decade in stages 4 and 5. This suggested that change occurs more rapidly prior to age 30. The 95% confidence interval also increased with age but was much narrower than in the previous component. Following the individual analysis of each component, they were summed (components I + I1 + 111) to obtain a total score per rib (Table 2). These scores ranged from 3 to 15, and the mean age per score increased from 17 to 64.Inconsistencies occurred only with scores of 12 and 15 and did not exceed 1 and 6 years, respectively. The results of the analysis of variance and related statistics appear in Table 3. Components I1 and I11 attained the highest F-ratios, indicating that they are more age dependent than component 1. The F-ratio for the total TABLE 2. Summary statistics for the components Stage or Mean score N age SD 95% Confidence interval Age SE ofmean range I-Pit deoth 1 9 20.3 3.32 1.11 2 29 30.7 12.40 2.30 3 31 40.9 13.72 2.46 4 9 55.0 15.39 5.13 5 4 57.5 12.92 6.46 Total 82 37.9 16.15 1.78 11-Pit shape 1 4 17.3 0.50 0.25 2 15 22.8 3.28 0.85 3 28 30.5 9.61 1.82 4 22 47.1 11.61 2.48 5 15 61.6 12.94 3.34 Total 84 38.4 17.26 1.88 111-Rim and wall configurations 1 5 17.8 1.30 0.58 2 25 24.1 3.55 0.71 3 20 34.3 11.62 2.60 4 16 49.5 11.21 2.80 5 16 58.2 11.53 2.88 Total 82 37.8 16.67 1.84 Total component scores 3 17.0 0.00 0.00 3 4 2 19.0 i.4i 1.00 4 22.5 3.32 1.66 5 7 23.1 4.06 1.53 6 3.63 1.05 7 12 24.9 9 27.0 4.90 1.63 8 9 10 37.8 13.21 4.18 8 47.1 12.03 4.25 10 6 48.5 9.89 4.03 11 12 7 47.6 11.75 4.43 13 5 56.0 10.32 4.61 14 4 63.5 12.26 6.13 4 57.5 12.92 6.46 15 84 37.3 16.81 1.83 Total 17.8-22.9 26.0-35.4 35.8-46.0 43.2-66.8 36.9-78.1 34.8-40.9 17-25 18-64 21-67 32-76 44-70 17-85 16.5-18.0 21.0-24.6 26.8-34.3 41.9-52.2 54.4-68.8 34.7-42.2 17-18 18-30 19-66 26-67 44-85 17-85 16.2-19.4 22.7-25.6 28.9-39.7 43.5-55.5 52.0-64.3 34.2-41.5 17-20 18-31 21-66 32-71 43-76 17-76 17.0-17.0 17.0-31.7 17.2-27.8 19.4-26.9 22.6-27.2 23.2-30.8 28.3-47.3 37.1-57.2 38.1-58.8 36.7-58.4 43.2-68.8 44.0-83.0 36.9-78.1 33.8-41.0 17-17 18-20 18-25 18-30 19-31 21-36 24-66 30-64 41-67 32-67 44-7 1 52-76 44-70 17-76 METAMORPHOSIS AT THE STERNAL RIB END TABLE 3. ONEWAY analysis of variance of the components Sources of variation Sumof d.f. squares I-Pit depth 4 8,691.24 Between stages Within stages 78 12,438.28 Total 81 21,129.51 11-Pit shape 4 16,906.71 Between stages Within stages 79 7,817.53 Total 83 24,724.24 111-Rim and wall Between 4 15,764.18 stages Withyn stages 77 6,758.08 Total 81 22,522.26 Total component scores Between 12 15,372.15 scores Within scores 68 5,750.46 Total 80 21.122.62 Mean squares F-ratio '7 2,172.81 13.45" 0.41 161.54 4,226.68 42.71* 0.68 98.96 3,941.05 44.90" 0.70 87.77 1,281.01 15.15* 0.73 84.57 *Significant at P < 0.001 level or less component scores was slightly higher than component I, but lower than components I1 and 111. The F-ratio showed that the variation between stages was statistically significant in all components a t a probability level less than 0.001. Table 3 also contains the eta-squared (q2) values. These are particularly important since they explain the percentage of variation in the age variable that can be attributed to the metamorphoses chosen to define the components. Component 111, individually, attained the greatest percentage (q2 = 70%). This was closely followed by component I1 (68%), with component I a distant third. Combining all three increased this figure, only slightly, to 73%. The CROSSTABS procedure provided the frequency distribution of the components by age interval (decade) (Table 4).This analysis revealed that the majority of cases in each decade fell into two stages or less for individual components. The sum of components spanned a score range of 3 to 6 per decade. (It must be emphasized that a score is not equivalent to a stage.) The x2 test indicated that the distribution was statistically significant for all components, individually and in toto, a t a probability level less than 0.001. This table also pinpoints the onset and completion of a particular metamorphic stage in relation to age. In component 11, for ex- 153 ample, stage 2 is primarily defined by the formation of a V-shaped pit. This developmental feature starts in late adolescence, is most active in the twenties, and slows down and ceases by the end of the third decade. Of 15 specimens exhibiting this specific pit shape, 2 individuals (13%)were late adolescents, 12 (80%)were in their twenties, and 1 (7%)was in his thirties. This same developmental approach can be extended to the other morphologic features defining the components and further strengthens the association of these characteristics with age. DISCUSSION While previous research indicated that the rib and costal cartilage show age-related change, histologic studies have not been geared to the development of a technique, and radiographic works have not produced one that could yield an accurate estimation of age. Histologic studies by Sedlin et al. (1963) revealed that the cross-sectional area of the rib cortex increased rapidly until skeletal maturity. From the age of 20 to 35 years, this area declined sharply and continued its gradual decline after age 35. Epker and associates (1965) also dealt with cortical bone loss. Their findings indicated that the cortex became thinner with age but the actual diameter of the bone increased. While this information agreed with our own observations of pronounced changes in bone density and texture seen in the later stages of each component, histologic analysis of the cortex alone did not appear suitable for precise age determination. Radiographic works in general have been limited to rough correlations of age with increased mineralization of the costal cartilage. Since radiographic evaluation requires the availability of a n intact sternal rib cage including the cartilages, this type of analysis could not be used on skeletonized forensic and prehistoric cases. In addition to this limitation, these studies also did not result in the development of a technique that would yield accurate age estimation. Semine and Damon (1975) and McCormick (19801, however, felt strongly that the costochondral junction should be further studied and utilized as a n important indicator of age. The present study was comparable to those on the male pubic symphysis CMcKern and Stewart, 1957). As in the pubic symphysis, the metamorphic changes in the rib were discernible from one stage to the next in each 12 29 12 'x2 = 70.02 with 24 degrees of freedom (significant at P < 0.001). 'x2 = 130.43 with 28 degrees of freedom (significant at P < 0.001). 3x2 = 118.15 with 24 degrees of freedom (significant at P < 0.001). 4x2 = 151.85 with 72 degrees of freedom (significant at P < 0.001). 29 2 2 4 2 1 1 12 29 1 3 5 10 7 3 2 8 2 20 8 1 7 4 12 1 29 7 4 6 2 30-39 12 16 1 5 16 8 20-29 4 3 17-19 1 4 2 2 1 3 4 5 Total 7 Total N N 7 111-Rim and wall configuration3 1 4 3 2 3 4 5 7 Total N Total component scores4 3 3 4 1 5 1 6 1 7 1 8 9 10 11 12 13 14 15 Total N 7 2 3 4 5 Total N 11-Pit shape' 1 I-Pit depth' Components 2 14 3 4 3 1 1 1 8 5 14 3 9 3 15 3 9 1 2 15 8 1 1 2 2 1 1 2 2 4 8 4 4 8 Age interval 40-49 50-59 1 7 1 1 2 1 1 4 2 7 1 1 7 2 4 60-69 TABLE 4. Frequency distribution ofcomponents by age intervals 2 1 4 1 1 4 5 5 5 3 1 4 70-79 1 1 80-89 3 2 4 7 12 9 10 8 6 7 5 4 4 81 5 25 20 16 16 82 28 22 15 84 15 4 9 29 31 9 4 82 Total N METAMORPHOSIS AT THE STERNAL RIB END component. Further comparison indicated that the rib can provide a n age estimation for individuals up to the mean age of 58 (component 111)through 62 (component 11)to 65 (component I). The oldest specimen analyzed in the McKern and Stewart study was only 50 years old, compared with 85 years in our sample. This maximum age difference might partially account for the large standard deviation observed in this study. Critical factors one should consider when estimating age from the skeleton are interobserver error, human variability, health and disease status, and occupation. Our research indicated that the individual variation increased after the third decade. This could result in greater difficulty in assessment of the older ages. A similar increase in variation was also seen in the pubic symphysis. Relative experience of the observer can also affect estimation (Suchey, 1979). Suchey found that errors in estimating age were inversely correlated with the experience of the observer. A final problem is the durability of the rib through time against environmental factors. These effects would be most severe on individuals in stages 4 and 5 owing to the brittleness and fragility of the bone. It has been suggested that both biomechanical and physiologic factors, such as stresses produced during respiration and chest expansion, combine to create the transformations observed a t the costochondral junction (King, 1939; Semine and Damon, 1975). These effects would probably not be noticeable until rib growth is complete. It was felt that this occurs a t age 17 since we observed the first transition in sternal end morphology (from a flat to a cup-shaped extremity) at this time. This is compatible with the histologic findings of Sedlin et al. (1963) that maturity in the rib is complete prior to age 20. Ortner and Putschar (1981)have pointed out that cartilage is more resistant to the effects of intermittent and pulsating pressure than bone; therefore, cessation of growth could render the sternal extremity of the rib susceptible to reshaping around the costal cartilage with which it articulates. Histologically, the most important factor underlying the observed changes is the continuous periosteal deposition of new bone (Sedlin et al., 1963; Ortner and Putschar, 1981), possibly accompanied by periochondral ossification (King, 1939). Thus, the “deepening” of the pit seen with increasing age is actually a build-up of periosteally pro- 155 duced walls of bone surrounding the sternal extremity of the rib and extending over the costal cartilage. Another factor, endosteal resorption, must also be considered. Following ossification of the growth cartilage, the sternal extremity of the rib has no active growth zone. However, endosteal resorption continues at a n even greater rate than periosteal deposition, thinning, and in some cases eventually eroding through the floor of the junction. Although the metamorphoses described are assumed to occur as manifestations of normal aging, there are several factors known to affect the remodeling process which may alter the aging pattern of the rib and cartilage (Murray, 1936; Lacroix, 1951; Bourne, 1956; Frost, 1963; Hall, 1978; Raisz and Kream, 1983a,b).These factors include strenuous physical activity and heavy labor, endocrine disorders, chronic lung disease, drug use, sex differences, diet, and intercostal variations (Rist et al., 1928; Riebel, 1929; King, 1939; Heudtlass and Garre, 1940; Fischer, 1955; Lichtenstein, 1975; Semine and Damon, 1975). Among these factors there are two important issues particularly pertinent to this study. The first involves intercostal variation and positive identification of the fourth rib. Semine and Damon (1975) emphasized that the first rib changes with age a t a much faster rate than the lower ones. In observing radiographs provided by McCormick and Stewart (1983) we saw gradual increase in mineralization from the second rib. This suggests that a rib being identified as the third or fifth may not significantly differ in morphology from that of the fourth rib and may provide equally reliable results. Furthermore, side differences may play a role, however, McCormick and Stewart (1983) felt that this was not a factor. There has been no serious attempt made to assess age-related differences between adjacent ribs, along with any possible variation between the right and left sides. The second important factor is the difference between sexes noted in earlier radiographic studies (Falconer, 1938; Horner, 1949; Fischer, 1955; Elkeles, 1966; Sanders, 1966; Navani et al., 1974; McCormick and Stewart, 1983). Differences in hormonal production probably account for this variation in the aging pattern of the rib (King, 1939; Horner, 1949; Sanders, 1966; Semine and Damon, 1975). With this in mind, the next phase of 156 M.Y. I SCAN, S.R. LOTH. AND R.K. WRIGHT the authors’ investigation is under way to develop a n age-determination standard for females. ACKNOWLEDGMENTS The authors thank Cargil Hinzey, Dean Reynolds, and Eric Thompson for collecting the specimens. We are especially grateful to George Covaleski, Steve Corey, and Robert Hinman also of the Broward County Medical Examiner’s Office for their helpfulness in providing us with accurate records of the specimens. Karen I. Derrick was very helpful a t the beginning of the project. We wish to thank Carolyn D. Majd for her kind assistance in typing this manuscript. The authors also thank the reviewers for their constructive criticism. This investigation was supported by Florida Atlantic University Sponsored Research Grant No. 121210016 awarded to M.Y. Iqcan. LITERATURE CITED Acsadi, G, and Nemeskeri, J (1970) History of Human Life Span and Mortality. Budapest: Akademiai Kiado. Bourne, GH (ed)(1956)The Biochemistry and Physiology of Bone. New York: Academic Press. Eckert, WG, and Noguchi, ‘IT (1974) The Bibliography of References on Forensic Anthropology. Wichita, KS: Inform. Elkeles, A (1966): Sex differences in the calcification of the costal cartilages. Am. Geriatr. J. 14r456-462. Epker, BN, Kelin, M, and Frost, HM (1965) Magnitude and location of cortical bone loss in human rib with aging. Clin. Orthop. 4lt198-203. Falconer, B (1938) Calcification of hyaline cartilage in man. Arch. Pathol. 26t942-955. Fischer, E (1955) Verkalkungsformen der rippenknorpel. Fortschritte auf dem Gebiete der Rontgen Strahlen und der Nuklear Medizen 82t474-481. Frost, HM (1963) Bone Remodelling Dynamics. Springfield, IL: C.C. Thomas. Frost, HM (1976) Supracellular organization of bone turnover (remodelling) in larger mammals and its parameters. In ZFG Jaworski (ed): Proceedings of the First Workshop on Bone Morphometry. Ottawa: University of Ottawa Press. Hall, BK (1978) Developmental and Cellular Skeletal Biology. New York: Academic Press. Horner, J L (1949) Premature calcification of the costal cartilages: Its frequent association with symptoms of non-organic origin. Am. J. Med. Sci. 218:186-193. Heudtlass, AP, and Garre, 0 (1940) La calcificacion de 10scartilagos costales en la evolucion de la tuberculosis pulmonar. Prensa Medica Argentina 27:365-369. Hull, CH, and Nie, NH (1981) SPSS Update 7-9. New York McGraw-Hill. Igcan, MY (1983) A Topical Guide to the American Journal of Physical Anthropology: Volumes 22-53 (19641980). New York: Alan R. Liss. Kerley, ER (1970)Estimation of skeletal age: After about age 30 years. In TD Stewart (ed): Personal Identifica- tion in Mass Disasters. Washington, DC: National Museum of Natural History, pp. 57-70. King, JB (1939) Calcification of the costal cartilages. Br. J. Radiol. 12:2-12. Krogman, WM (1962) The Human Skeleton in Forensic Medicine. Springfield, IL: C.C. Thomas. Lacroix, P (1951) The Organization of Bones. Philadelphia: Blakiston Co. Levine, MH (1971) A Topical Guide to Volumes 1-21 (New Series) of the American Journal of Physical Anthropology. Philadelphia: Wistar Institute Press. Lichtenstein, L (1975) Diseases of Bone and Joints. Saint Louis: C.V. Mosby. McCormick, WF (1980) Mineralization of the costal cartilages as an indicator of age: Preliminary observations. J. Forensic Sci. 25t736-741. McCormick, WF, and Stewart, JH (1983) Ossification patterns of costal cartilages as an indicator of sex. Arch. Pathol. Lab. Med. 107:206-210. McKern, TW, and Stewart, TW (1957) Skeletal age changes in young American males. Analysed from the standpoint of age identification. Environmental Protection Research Div. (Quartermaster Res and Dev Center, US. Army, Natick, MA), Tech. Rep. No. EP45. Murray, PDF (1936)Bones: A Study of the Development and Structure of Vertebrate Skeleton. London: Cambridge University Press. Navani, S, Shah, JR,and Levy, PS (19741 Determination of sex by costal cartilage calcification. Am. J. Roentgen. 108:77 1-774. Nie, NH, Hull, CH, Jenkins, JG, Steinbrenner, K, and Bent, DH, (1975) SPSS. New York: McGraw-Hill. Nishino, K (1969) Studies on the human rib-cartilage. Kekkaku 44:131-137. Ortner, DJ, and Putschar, WGJ (1981) Identification of Pathological Conditions in Human Skeletal Remains. Washington, D.C.: Smithsonian Institution Press. Raisz, LG, and Kream, BE (1983a) Regulation of bone formation. Part 1. N. Engl. J. Med. 309(11):29-35. Raisz, LG, and Kream, BE (1983b) Regulation of bone formation. Part 2. N. Engl. J. Med. 309(2):83-89. Riebel, F (1929) Ossification of the costal cartilages: Their relation to habitus and disease. Am. J. Roentgen. Rad. Ther. 21:44-47. Rist, E, Gally, L, and Trocme, C (1928) L’ossification des cartilages costaux dans I’esp8ce humain. Presse Medicale 41:641-644. Sanders, CF (1966) Correspondence: Sexing by costal cartilage calcification. Br. J. Radiol. 39.233. Sedlin, ED, Frost, HM, and Villanueva, AR (1963)Variations in cross-section area of rib cortex with age. J. Gerontol. 18:9-13. Semine, AA, and Damon, A (1975) Costochondral ossification and aging in five populations. Hum. Biol. 47:lOl-116. Stewart, TD, and Trotter, M (eds) (1954) Basic Readings on the Identification of Human Skeletons: Estimation of Age. New York Wenner-Grenn Foundation. Suchey, JM (1979) Problems in the aging of females using the 0s pubis. Am. J. Phys. Anthropol. 51t467470. Thompson, DD (1979) The core technique in the determination of age at death in skeletons. J. Forensic Sci. 24t902-9 15. Ubelaker, DH (1978) Human Skeletal Remains: Excavation, Analysis, Interpretation. Chicago: Aldine.