Osteological Manifestations of Age in the Adult

Skull

Historically , the skull was the first part of the skeleton system atically investigated for the estimation of age at death. By the end of the ninete enth century , studi es of cranial sutur e closure had been conducted by Broca (1861) , Ribbe (1885), Schmidt (1888), Dwight (1890 a), and Parsons and Box (1905 ).

Thyroid cartilage

Because the thyroid cartilage is frequently missing from most archaeological and forensic skeletons, it is rarely thought of as a site for age estimation. However, a number of studies have associated age with the degree and progression of ossification of the thyroid cartilage (Yoshikawa, 1958; Vlcek, 1980; Cerny, 1983). The most notable of these was Vlcek's presentation of nine phases of progressive ossification in males and their correlation with age from 15 to nearly 70 years. However,_he noted that difficulties arose after age 50. Cerny (1983) tested Vlcek's method on five ossified cartilages and found that although it was fairly easy to classify a specimen of known age, this was not the case when he attempted to determine age from an unknown individual. He cautioned that lacunar resorption may result in a deceptively youngerlooking bone and that damage ca? obscure the actual manifestations of age. Cerny (1983) concluded that thyroid cartilage ossification might best be used as a complement to other methods.

Scapula and sternum

Two of the least-used bones for age estimation are the scapula and sternum. Aging in the adult scapula was investigated by Graves in 1922. Using the HamannTodd collection, he noted two "diametrically opposed" types of age-related manifestations: ossification and atrophy. He identified six loci undergoing postmaturity ossification, including lipping of the glenoid fossa, and four types of atrophic changes in the general character of the scapular bone. However, he did not associate them with specific ages. Graves used transillumination to pinpoint atrophic alterations in the bony tissue itself. He warned that race, sex, and disease may affect the manifestations of age at this site, but did not study them personally. Krogman (1949) later supplied age ranges for Graves's features. Basically, this method can only furnish a general delineation of openended intervals such as "under 25" or "over 50."

Vertebral column

As early as 1943 , Stewart noticed that osteoarthritic vertebral lipping increased with age. In 1958 , he published the results of a study of both the Terry collection (N = 87) and Korean war casualties (N = 368) in which he quantified the degree of osteophytosis and attempted to correlate it with age. He rated these variables on an admittedly subjective scale of O to + + + + , averaged the total for the cervical, thoracic, and lumbar regions separately, and then plotted the correlation of each region with age on graphs. Results indicated that during the first 50 years of life, the number, rather than the size of the osteophytes , increased. The first significant increase in osteophytic size was not observed until after age 51. Finally , some individuals did not show osteophytosis even into their eighties, in contrast to others in their forties who showed considerable lipping.

Sacroiliac region

The effects of age can be seen in two ways at the sacroiliac joint: changes in the topography of the articular surfaces of the sacrum and ilium, and ankylosing of the joint itself. Brooke (1924) wrote that this joint does not show sex differences until puberty, at which time males "progress along lines of strength" and females sacrifice strength for mobility. When considering this region, it must be kept in mind that the pelvic structure is more influenced by sex-linked factors than any other part of the skeleton.

Pubic symphysis

Like the cranial sutures, the pubic symphysis has been the focus of a lion's share of the studies and methods for age estimation. As early as 1858, Aeby noted agerelated change at this site . Although his studies focused on the soft tissues of this region , he did observe marked changes in the bony syrnphyseal face. The general progression of the aging process at this site is illustrated in Figure 3. As with cranial sutures , the pubic bone was formally ushered in as a locus for age determination by Todd (1920 , 1921a,b) with the intro - duction of his developmental phases.