Letter to the Editor: Comments on “A new method to estimate adult age-at-death using the acetabulum” (Calce, 2012)

A test and analysis of Calce (2012) method for skeletal age-at-death estimation using the acetabulum in a modern skeletal sample

In forensic anthropology, the age-at-death of an adult individual is one of the most complex parameters of the biological profile to estimate. The present study aims to evaluate the reliability of the Calce (2012) method for the estimation of age-at-death through acetabulum changes in a sample of Portuguese origin. This method consists of the global analysis of acetabular age-related morphology with focus on three specific traits, namely the acetabular groove, the osteophyte development of the acetabular rim, and the apex growth. This method was tested in 120 individuals sampled from the Twenty-first Century Identified Skeletal Collection (University of Coimbra, Portugal). The test sample is composed of 60 males and 60 females, aged between 25 and 99 years, with well-preserved os coxae. The results showed that only 60% of the individuals were correctly attributed to the age group defined by the technique. The comparison with previous studies in other populations shows significant inter-population differences in the relationship between the acetabulum variables used by Calce and age-at-death. The obtained results advise caution in the use of the Calce (2012) method to estimate the age-at-death of unidentified skeletons.

The influence of bone loss on the three adult age markers of the innominate

To evaluate the influence of bone loss on the three adult age markers of the innominate, 30 males and 30 females aged between 16 and 80 years coming from the British Coventry collection were analyzed. The pubic symphysis, auricular surface, and acetabulum age variables were evaluated following the descriptions of Schmitt, Buckberry-Chamberlain, and Rissech, respectively. The second metacarpal cortical index was used to evaluate bone loss. Possible sexual differences in metrical variables were explored by a Student t-test taking into account the entire sample. The possible relationships between the cortical index and the three age methods' stages were assessed by the Kruskall-Wallis test and Spearman's correlation coefficient. There were no sexual differences in the cortical index. In general, we observed no significant differences between the cortical index in the different stages of the pubic symphysis, auricular surface, or acetabulum variables in men and women. Most correlation coefficients are negatives, and their absolute values are between 0.001 and 0.44, indicating an extremely low influence of bone loss on the analyzed variables. Our findings suggest little influence of bone loss in the three ageing methods. However, further research on this topic is necessary. This is the first study to analyze the influence of bone loss in the ageing changes undergone by the variables of the three adult age indicators of the innominate taking into account both sexes.

Shape variability of the adult human acetabulum and acetabular fossa related to sex and age by geometric morphometrics. Implications for adult age estimation

This study aims to explore shape variability of the acetabulum during the human adult life span, in relation to sex and age. The human acetabular shape was analysed in 682 os coxae from three different documented skeletal collections from the Iberian Peninsula. Two landmarks and thirty-two sliding semi-landmarks were used for the geometric morphometric procedures and a clock-wise standard was used for orientation. The 180° meridian (6:00) line was positioned over the midpoint of the acetabular notch and 36 reference points in 10° increments along the rim were marked. Data showed that size, sex and age significantly influence acetabular shape variation. Sex differences were significant in individuals younger than 65 years old and were characterised by males exhibiting relatively extended acetabular rim profiles from 10:00 to 1:00, narrower acetabular notches, and reduced acetabular fossae. In addition, three main age-related changes occurred to the acetabular shape in both sexes: outer acetabular profile modification, with extension from 10:00 to 1:00 and reduction from 7:00 to 9:00, acetabular notch narrowing, and acetabular fossa reduction. The age-related changes that were observed are shared by both sexes and seem to be related to bone production associated with age. Specifically, age appears to affect the entire border of the lunate surface: the acetabular rim, both acetabular horns, and the outer edge of the acetabular fossa. Furthermore, shape data confirmed the clover-leaf shape of the acetabular fossa in both males and females. These results improve our understanding of acetabular shape, and assist in refining age-estimation methods and enhancing hip surgery and rehabilitation.