Sex and ancestry estimation in South Africans from measurements of the calcaneus and talus - a validation study.

Forensic anthropological methodology needs to continuously be tested and validated to remain on par with international standards of best practice. The present study aimed to validate previously published metric and non-metric methods for estimating sex and population affinity from the calcaneus and talus in black and white South Africans. The calcanei and tali of two-hundred individuals, equally distributed by sex and population, were measured and the validity of the discriminant functions were assessed. Only some functions estimating sex using both skeletal elements and estimating population affinity using the calcaneus are valid, with present and original accuracies not differing significantly (p > 0.05). Population affinity estimation functions using the talus, however, are not valid. Functions yielding accuracies in the present study between 50.00% and 74.00% should not be used as these rates are only slightly above chance (50.00%), but functions yielding accuracies of 75.00% and above may be considered for use in forensic casework. Almost all functions yielded accuracies significantly lower (p < 0.05) for females and for black individuals compared to their male and white counterparts, respectively. As a result, the classification of individuals as female or as black should particularly be interpreted with caution. This study also assessed the validity of previously described morphological methods used to estimate population affinity using the calcaneus. The number of talar articular facets present differs significantly between population groups and the validity of this method was therefore confirmed. These methods should be further validated using more modern skeletal collections or living individuals using various virtual methodologies.

Radiological detection of sharp force skeletal trauma: an evaluation of the sensitivity of Lodox in comparison to CT and X-ray.

Victims of violent crime often have evidence of sharp force trauma (SFT) which needs to be examined to accurately investigate these cases. The abilities of CTs, X-rays, and Lodox to detect skeletal SFT defects and the minimum number of impacts were assessed, as were their abilities to macroscopically interpret SFT with the aim of identifying the class of weapon used. Ten pigs were, post-mortem, stabbed using a kitchen knife on one side of the body and chopped using a panga on the other side. They were then scanned and macerated. The number of SFT defects, type of SFT, and minimum number of impacts identifiable osteologically were recorded, as well as when using each imaging modality. CTs were most sensitive for detecting stab and chop defects (56.7% and 78.3%, respectively) and the minimum number of impacts (82.8%), while X-rays were least sensitive (17.2% for stab wounds, 46.5% for chop marks, and 43.5% for impacts). Lodox detected 26.8% of stab defects, 59.3% of chop marks, and 58.4% of impacts. The type of SFT for more than 70.0% of identified defects was correctly classified using all methods, while only Lodox had moderate sensitivities for stab wounds (52.4%). When radiological assessments of skeletal SFT are required, CTs should be performed, but Lodox can be used as an alternative. However, dry bone analyses still produce the best results and should be performed whenever possible. Macroscopic interpretations of skeletal SFT to broadly determine the class of weapon used is possible radiologically.

Diagnostic accuracies of CTs, X-rays and Lodox to detect blunt force trauma in adults, using a pig model.

The accurate radiological detection of skeletal trauma is crucial for the investigation of blunt force trauma (BFT) cases. The sensitivities of CTs, X-rays and Lodox in identifying BFT fractures and minimum number of impacts in pigs, used as proxies for adult humans, were assessed. Ten human sized pig carcasses were struck with a mallet and scanned, after which the number of fractures and minimum number of impacts detected radiologically were recorded. Pig carcasses were then macerated, and the defleshed, skeletonized remains were considered the gold standard as far as number and location of fractures were concerned. CTs were most sensitive in identifying fractures and impacts in all body regions, with overall sensitivities of 55.4% and 71.5% respectively, while X-rays and Lodox had sensitivities of 25.8% and 29.3% for fractures, and 43.5% and 41.1% for impacts, respectively. All modalities were highly specific for identifying fractures (CT: 99.1%; X-ray: 98.9%; Lodox: 99.4%). CTs should be used to analyze blunt force trauma when a radiological assessment is required, but an examination of the defleshed bones remains the gold standard for the deceased whenever feasible. X-rays and Lodox have limited diagnostic value in these cases and relying on them to detect fractures may compromise the accurate forensic investigation of blunt trauma victims. However, the use of Lodox for initial screening of major trauma is still of value. Sensitivities are generally higher for detecting fractures in pigs compared to piglets, indicating that increased diagnostic value is achieved when imaging pigs compared to piglets.

A comparison of computed tomography, X-ray and Lodox® scans in assessing pediatric skull fractures using piglets.

Skull fractures are common in children both due to abuse and accidental incidences. The accurate detection of these fractures may therefore be critical. The aim of this study was to investigate the reliability of CT, X-ray, and Lodox® scans, the latter which has not previously been evaluated and is commonly employed in South Africa, in detecting the number, location and type of pediatric skull fractures. Blunt force trauma was inflicted with a mallet on ten piglet skulls, which were CT, X-ray, and Lodox® scanned and then macerated. The number, location, and type of skull fractures visible using each imaging modality, and on the cleaned skulls, were recorded. Sensitivities and specificities of each method were calculated. For fracture number and location, CTs had a sensitivity of 47.3%, X-rays 22.4% and Lodox® 23.3%. For fracture type, sensitivities were 46.1%, 16.6%, and 17.8% for CT, X-ray, and Lodox® , respectively. Specificities were high (92.5%-100%) which reduces the risk of incorrectly diagnosing fractures. However, low sensitivities increase the risk of failing to identify fractures and possible victims of abuse. Osteological analysis should preferably be the method of choice when evaluating pediatric skull trauma, and CTs should be used when osteological analysis is not feasible. If CT scanners are not available, X-rays and Lodox® may have to be used. In these cases, additional radiographic views of the skull are imperative and may increase the sensitivity of these methods, although they are not recommended to detect exact pediatric skull fracture number, location, and type.

Forensic imaging: The sensitivities of various imaging modalities in detecting skeletal trauma in simulated cases of child abuse using a pig model.

Physical child abuse is a major problem in South Africa and throughout the world, and the detection of skeletal trauma in victims of abuse may be critical in the accurate investigation of these cases. Since many of these fractures are not detected during traditional autopsy, the use of various diagnostic imaging tools is implemented in order to aid in the detection of trauma. In South Africa, Lodox (low-dose full-body X-ray) is commonly used in forensic mortuaries and the aim of this study was to assess the sensitivities of CT, X-ray and Lodox, in comparison to dry bone as the gold standard, in detecting both the number of fractures and minimum number of impacts in piglets subjected to blunt force trauma. Ten piglets were beaten with a mallet post-mortem in every region of the body. CT, X-ray and Lodox scans were taken of each piglet, after which the piglets were macerated in order to conduct an osteological analysis of the remains. The number of fractures and impacts present in each scan and on the dry bone were recorded. CT scans were the most sensitive in identifying trauma in all regions of the body, detecting 73% of fractures and 79% of impacts. X-ray and Lodox scans were less sensitive in detecting both fractures (50% and 42% respectively) and impacts (59% and 54% respectively). An assessment of the directionality of trauma was possible using dry bone and CT scans, but not when using X-rays or Lodox scans. CT scans can be used to assess skeletal trauma in suspected victims of child abuse, but the use of X-ray and Lodox scans is not recommended other than for initial screening procedures. Osteological analysis, however, is still considered the gold standard and should be performed whenever possible.

A comparison of the direct and indirect methods of estimating skeletal height from tibial fragments in black South Africans.

The estimation of maximum bone length from its fragments is important in forensic anthropology as these length estimates can be used to estimate the total skeletal height (TSH), and thereby stature, of unknown skeletal remains. This is known as the indirect method of stature estimation. Alternatively, TSH can be estimated directly from bone fragments without first estimating maximum bone length. While regression equations for estimating maximum bone length from its fragments exist for long bones of the upper and lower limbs, these equations are population- and sex-specific and their use on populations other than the one they were derived from is not recommended. The aim of this study was therefore to develop formulae for estimating maximum tibial length from its fragments in black South Africans, which previously did not exist, and to compare the accuracies of the direct and indirect methods of estimating TSH from tibial fragments. Several measurements representing fragments were measured on the tibiae of 99 male and 99 female black South Africans, and equations estimating tibial length from these measurements were derived. Correlation coefficients of each equation were significant, and all equations estimated tibial length with moderate to high accuracy. A comparison of the standard errors of estimate (SEEs) between the direct and indirect methods of stature estimation indicate that the direct method is more accurate and should be used to estimate stature from tibial fragments when such equations exist.

Using tibial fragments to reconstruct the total skeletal height of black South Africans.

Stature is an important component of the biological profile of unknown skeletal remains and regression equations for estimating stature have been derived for a number of bones. However, bones are rarely recovered intact in both forensic and archaeological cases, and regression formulae for fragmentary remains have therefore been developed. These equations are, however, both sex- and population-specific, and while formulae exist for many populations, those using fragmentary tibiae do not exist for black South Africans. The aim of this study was therefore to establish regression equations for estimating total skeletal height (TSH), and thereby stature, from tibial fragments in a black South African population. A sample of 99 male and 99 female black South African skeletons were obtained from the Raymond A. Dart Collection of Human Skeletons and the TSH of each skeleton was calculated using the anatomical method. Eleven additional measurements representing tibial fragments were taken on each tibia, and both uni- and multivariate equations were established for estimating TSH from these fragments. All tibial variables were significantly, positively correlated with TSH, and equation correlations ranged between 0.41 and 0.91. The range of standard errors of estimate for the derived sex-specific (3.43-5.06 cm) and sex-pooled (3.44-5.94 cm) multivariate equations were slightly larger than those reported for intact tibiae in black (2.78-3.06 cm) and white (2.59-3.16 cm) South Africans. All uni- and multivariate-equations estimated TSH with moderate to high accuracy, which indicates that in the absence of intact tibiae, the equations presented in this study can be used to give accurate estimates of TSH, and thereby stature, for black South Africans.