Age estimation based on pubic symphysis - Essay Example

Age Estimation based on Pubic Symphysis: An evaluation of the techniques and methodologies involved. This paper will discuss and evaluate the various methodologies and techniques based upon age estimation using the Pubic Symphysis which is a midline cartilaginous joint connecting the superior rami of the left and right pubic bones of the human skeleton and is located near the urinary bladder and above the external genitalia. The changes in the Pubic Symphysis are of great importance in the field of forensic osteology as they can be used for estimation of the age of the adult skeletons.This can be estimated from the changes on the surface of this joint which will give a predictable estimated of the age of the deceased. (Telmon, N, 2005). Amongst other techniques to estimate the age of the skeleton dentition is also frequently used to estimate age and at times this might be the last resort, given the complete mutilation or decomposition of the corpse This is because in such a situation it is impossible to base any conclusions pertaining to age or identity upon other parts of the anatomy (N.J. Modi 1988). Age estimation based on the changes within the surface of the pubic symphysis is another method which has come to be regarded as as a reliable criterion for the estimation of age which has received much attention with in trhe field of forensic osteology which relates to the observation of the changes in pubic symphysis, particularly pertaining to the age related changes of adult humans between the ages of 20-50 years, which is a time when the skeleton itself goes through rapid growth related changes. (W.M. Krogman et al 1986 :45). Therefore morphological changes in the symphyseal surface of pubic bones have been evaluated by the forensic anatomists through methods like Todd’s phase system for White Males (T.W. Todd, 1920,1921) Mckern and Stewart’s three-component system with five active developmental stages for males ( Mckern and Stewart, 1957) Hanihara and Suzuki’s multiple regression analysis and quantification theory model ( Suzuki,1978) be consistent in the way you list these. Suchey–Brooks phases (S.T. Brooks 1955) which are more detailed for the examination of the male pubic symphysis. Based on the above this paper explores these methodologies pertaining to age estimation using morphological features of the pubic symphysis and goes onto evaluate their precision in the light of academic opinion.. Introduction As mentioned above, at the culmination of the growth process which also brings about the full eruption of the dentition growth it is possible to experience complications in the estimation of age , relying on evidence of degenerative processes. (Gilbert and Mckern 1973) .However, age estimation at death can be made from multiple methods out of one of which will be discussed below to be the symphyseal formula technique where as it has been “found that age estimates based on this single event are more dependable than similar age estimates from other bones. This technique has made age estimation from unknown skeletal remains more realistic, more accurate and more dependable.” (Parikh, C. k., 1990). There a number of techniques available with in the forensic osteology to estimate the survival, social adjustment and age of the populations based on the patterns of morbidity and mortality and these have included techniques like pubic symphysis morphology, auricular surface morphology, age-related size distribution, tooth wear, epiphyseal closure, dental eruption patterns. All these techniques are well utilized if the skeleton is still in its period of growth and development and their use may give very precise results However as soon as the growth and development process ceases. it becomes more and more difficult to give a precise assessment of the age based upon the evidence of the degenerative processes.Thus public morphology provides a good way of establishing consistent findings for the determination of age at death (mostly) of the corpse. Age is thus determined by reviewing the morphological changes of the articular surfaces of the pubic symphysis to provide as reliable postcranial age estimates for the dead adults. These morphological changes will include variations in the pubic symphysis surface.The area that will usually be analyzed to determine age is what is known as the anterior aspect of articulation between the two innominates in the pelvic bone.Thus Age-at-death estimation based on the evaluation of the metamorphic changes in the symphyseal surface of pubic bones forms an important aspect of bio-archaeological and forensic analysis. (Gilbert and Mckern 1973) .The different morphological features in the pubic symphysis will reflect and will be observed for maturation, remodelling and degeneration, that reflect the biological and chronological age of the individual as closely as possible. (Kemkes-Grottenthaler A 2002). Description of the Pubic Symphysis The Pubic symphysis has been described in the nature of a joint which is “a junction of the two pubic bones lying roughly 4-5 inches below the navel. This junction is bridged by cartilage that acts as a cushion between the two bones.” (Houck, M. M. & Siegel, J. A., 2006) –.The pubic symphysis is the central cartilaginous joint which unites the superior rami of the left and right pubic bones. The location of the pubic symphysis is anterior to the urinary bladder and superior to the external genitalia is above the vulva for females and above the penis for males. It belongs to the category of non-synovial amphiarthrodial joints. (Kemkes-Grottenthaler .A 2002). The pubic symphysis has its anterior width 3-5 mm greater than its intrapelvic posterior width. Pubic symphysis is connected by fibro cartilage and its centre is avascular. The ends of both pubic bones are covered by a thin layer of hyaline cartilage. The fibro cartilaginous disk is reinforced mainly by many ligaments of which superior and inferior ligaments are important. (Kemkes-Grottenthaler A 2002). The strong and thicker superior ligament is reinforced by the tendons of rectus abdominals, obliques externus, gracilis and thigh adductors muscle. The inferior ligament of pubic arch is known as the arcuate pubic ligament. The pubic symphysis is 9-10 mm width during birth, with thick cartilaginous end plates. During adulthood the end plates decrease in width alongwith thinner layers. (K. Hanihara1952) .Also the pubic disc is thicker in females which permits more movement of the pelvic bones, and thus provides a greater diameter of pelvic cavity during delivery.(See diagram below for the view of the anterior ligament)1 The pubic symphysis :pregnancy and other changes During pregnancy, hyaline cartilage will become more flexible preparing the pelvic bones to be more flexible for delivery (K. Hanihara1952). The normal non-pregnant gap of the symphysis pubis is 4-5 mm but in pregnancy, the width increases at least by 2-3 mm, and thus, there is a total width of up to 9mm for pregnant women. During delivery, the pubic symphysis innominates separate to some degree and this separation can lead to diastases of the symphysis pubis. (K. Hanihara1952) . The diastases could be the result of a rapid birth or a forceps delivery or may be prenatal. Diastasis of the pubic symphysis is a symptom of pelvic girdle pain. Historically, symphysiotomy used to be done when labour failed to progress due to the large size of the head of the foetus and consequently it used to be that the foetus’s skull was crushed. (K. Hanihara1952) .Fractures of the pelvis are important in forensic pathology in two aspects – First, a great amount of force is required to disrupt the pelvic ring. Secondly, because the pelvis is a ring, disruption of any part of it is usually associated with disruption of another part of the ring. (Walker RB et al 1994) “Pelvic disruption or fractures are classified by the direction of the force. There are four categories, 1. Anterior posterior compression. 2. Lateral compression. 3. Shear 4. Complex fractures.” (De Maio, V. j. & Di Maio, D. J., 2001) In fractures due to antero posterior compression, a direct blow occurs either to the pubic symphysis or the posterior iliac spines and as a result, there is separation of pubic symphysis anteriorly. (Walker RB et al 1994).In Lateral compression, disruption of the pubic symphysis can also occur. Shearing injuries can occur due to extremely severe force which also leads to disruption of pubic symphysis (Walker RB et al 1994). An evaluation of the Pubic symphysis age estimation methodologies The morphological changes in the symphyseal surface of the pubic bone were first studied in depth by Todd, who divided the changes into 10 phases. Later, Todd’s work was advanced by McKern and Stewart, who changed Todd’s holistic method into a sectional evaluation. (Walker RB et al 1994 and see above for references and works). Their work was based on young males who were killed in the Korean War and focused only on identifying soldiers of same sex/age category. Later these studies were modified by the techniques developed by Brooks, Katz, and Suchey, beginning with Brooks (Kimmerle EH. 2004)..The subsequent studies were also critical of Todd’s technique for example according to Katz and Suchey the problem with the original Todd method was that it tended to over estimate the age-at-death for individuals over the forty years age bracket .Later researchers like Kemkes-Grottenthaler (Kemkes-Grottenthaler A 2002). were also of the opinion that that the modified six-phase system is a more accurate estimator than the original Todd system. (Kimmerle EH. 2004).Today the Suchey-Brooks system which is an offshoot of the Todd method is currently used throughout the world as the standard for estimating age from the pubic symphysis. (Kimmerle EH. 2004).Other criticisms have included the fact that the pubic symphysis method for age estimation is less reliable than that for males due to the changes that occur during pregnancy and childbirth. (Kimmerle EH. 2004). Furthermore there have been studies that show different variations in results for the application of this test which may be a result of cultural differences pertaining to lack or availability of health care access, nutrition, or activity which will subsequently affect the bone density of the subjects or even cause premature degeneration, which is particularly true for older subjects. ( Katz and J.M. Suchey 1986).Based on the above at times the skeletal remains of females (including the pubic symphysis) may degenerate earlier due to pregnancy, nutritional differences, bone mineral density, and osteoporosis. ( Katz and J.M. Suchey 1986). Age changes in Pubic Symphysis For the age estimation of an individual from the symphyseal surface of pubis, factors like the formation of dorsal plateau, a ventral rampart and the symphyseal rim with five stages of development are all taken into consideration. (Gilbert and Mckern 1973).The age range extends from the second into the sixth decades and correlates reasonably with the age changes in long bones and the skull. (Gilbert and Mckern 1973) .The pubic symphysis is probably the best single criterion for determining age from third to sixth decades. “Symphyseal surface changes are helpful in age estimation from 18 years to 60 years. The symphyseal surface can be sawn off even at autopsy, and studied for age assessment in this age group, together with cranial sutures.” (Modi, J. P. 2002) The surface of the pubic symphysis before the age of 20 has a layer of compact bone near its surface. At about 20 years, it becomes irregular or uneven with wavy ridges called billowing which runs transversely across the articular surface. (N.J. Modi 1988) Between 24 and 36 years, the ridges gradually disappear and a granular appearance comes over the surface and ventral (outer) and dorsal (inner) margins are completely defined. (N.J. Modi 1988). Early in the fifth decade, the symphyseal face acquires an oval, smooth surface with raised upper and lower edges. (N.J. Modi 1988).Towards the end of the fifth decade, a narrow beaded rim develops on the margins. During the sixth decade, surface erodes and breakdown of ventral margin begins. (N.J. Modi 1988). The surface becomes irregularly eroded in the seventh decade. “If male criteria are used for females, the age would be underestimated by about ten years.” (Narayan, K. S., 2004). The Todd Method (T.W. Todd, 1920,1921) Todd propounded a ten stage method for assessing the surface of the Pubic Symphysis to be able to estimate age of an adult. Using this method the variances in the symphyseal surface over time will be possible to predict as it has a tendency to have a surface marked by increasing porosity after 40 years. The ten phases are outlined below: Phase 1. The face of the symphysis is rugged, transversed by horizontal ridges separated by well differentiated grooves. There is no distinction in size between the upper and lower ridges. (Age 18-19) Phase 2. Rugged symphyseal surface.Horizontal grooves are filled near their dorsal limit with new, finely textured bone. Dorsal delimiting margins start to develop. (Age 20-21) Phase 3 Progressive destruction of ridge and furrow occurs. Dorsal platform begins to develop. Bony nodules are present and dorsal margin develops with sharp lipping. Ventral bevel become more marked. (Age 22-24) Phase 4 Ventral bevelled area increases and it is associated with a general decrease in ridge and furrow formation. The dorsal platform is well developed thus shaping dorsal margin. Delimitation of lower extremity starts. (Age 25-26) Phase 5 Little change in dorsal platform and symphyseal face. Margins are more sharply slipped and more clearly defined. The lower extremity is better defined. There is formation of upper extremity with or without the involvement of bony nodule. (Age 27-30) Phase 6 The extremities are defined clearly. Ventral rampart is developed with completion. The activity of symphyseal face is recognised by the retention of some granules. There is failure of ventral aspect of pubis nearer to the ventral rampart to become transformed into a compact surface. As a result, the rampart is somewhat undermined. The pectinate outline of the dorsal margin and slight ridge and furrow system is retained. The ventral margin and dorsal margin show little signs of a lip. (Age 30-35). Phase 7. The granular aspect of the face and ventral rampart of pubic bone changes to a fine-grained or dense bone. Symphyseal face shows changes slightly and ventral aspects show marked changes indicating a decrease in activity. There is no formation of symphyseal rim. The tendinous and ligamentous attachments show no ossification. (Age 35-39) Phase 8. The symphyseal face and ventral aspect of the pubic bone are smooth and inactive. There is completion of oval outline. Extremities are clearly defined. The symphyseal face develops no distinct rim. There is no marked lipping of ventral or dorsal margins. The ligamentous and tendinous attachments show ossification particularly those of sacro-tuberous ligaments and gracillis muscle. (Age 40-45) Phase 9. A more or less marked rim develops on the symphyseal face. There is uniform lipping of the dorsal margin with irregular lipping of the ventral margin. (Age 45-49) Phase 10. The ventral margin is eroded at a greater or lesser extent than its length which continues into the symphyseal face. There is irregular ossification and rarefaction of the face. (University of Notre Dame, n.d. cited in Buikstra, J. & Ubalekher, D. H.) (University of Notre Dame, n.d. cited in Buikstra, J. & Ubalekher, D. H., 1994) Suchey/Brooks Method (for females): ( S.T. Brooks 1955) Phase1. There is billowing of the surface of the symphyseal face which is made up of ridges and furrow including the pubic tubercle. There is well marked horizontal ridges. The ventral bevelling gets started. Even though ossific nodules are seen on the upper extremity, an important feature of this phase is the lack of delimitation for either extremity (upper or lower). Phase 2. There is still development of ridges in the symphyseal face. The lower and upper extremities show early stages of delimitation with or without ossific nodules. Formation of ventral rampart as an extension of either or both extremities occurs. Phase 3. Lower extremity is well delimited and the process of completion of ventral rampart occurs. The upper extremity is formed by the fusing of ossific nodules, and extends along the ventral border. The symphyseal face may be either smooth or retain distinct ridges. There is completion of dorsal plateau. Symphyseal dorsal margins show no lipping and there are no bony ligamentous outgrowths. The Suchey //Brooks Method for males includes a few more phases. Phase 4. There occurs a fine-grained symphyseal face, although remains of furrow and ridges may remain. At this stage, the oval outline is complete, though a hiatus may be seen in the upper aspect of ventral circumference. The pubic tubercle is fully separated from the face of symphysis. A distinct rim is seen on the symphyseal face. Towards the inferior part of the pubic bone, there occurs bony ligamentous outgrowth ventrally. The dorsal border shows slight lipping. Phase 5. There is a slight depression of the symphyseal face in relation to a completed rim. The dorsal border shows moderate lipping with distinct ligamentous outgrowths on the ventral border. There seems to be little or no rim erosion, though breakdown is possible on superior aspect of ventral border. Phase 6. As the rim erodes, the symphyseal face shows continuing depression. The ligamentous attachment on the ventral side is marked. The pubic tubercle appears as a distinct bony knob. As the continuing process of changeable ossification proceeds, the symphyseal face becomes more and more eroded and disfigured and may be pitted or porous. Crenulations may occur, leading to irregular shape of the face. “A comparison of 52 Suchey-Brooks scores assigned to digital images and actual bone revealed that age assessment from digital images can be completed with accuracy. Coefficients of concordance imply that there significant agreement between osteological assessment of aging criteria from digital images and direct observation—greater than random change alone (p Read More