Dorsal calcaneal wedge removal in zadek osteotomy: A cadaveric study.

BACKGROUND: Insertional Achilles tendinopathy (IAT) is a common pathology with multiple surgical interventions available for treatment. The Zadek, dorsal closing wedge calcaneal osteotomy (ZO) has been demonstrated to be effective treatment of IAT. There have been various recommendations in the literature as to what measurement of wedge removal should be considered ideal to produce greatest postoperative range of motion (ROM), thus postoperative biomechanical potential. Accordingly, the purpose of this cadaveric study was to assess the range of motion achieved after various measurements of wedge removal by ZO. METHODS: The ZO was performed on six cadaveric specimens. A 7.5 mm and 15 mm wedge osteotomy was marked and sequentially completed on each specimen. Lateral fluoroscopic imaging was utilized to take preoperative and postoperative ROM measurements for each osteotomy. Dorsiflexion (DF) and plantarflexion (PF) ROM arcs were measured for each wedge size and compared by t-test. Effect sizes were calculated by Cohen's d analysis. RESULTS: Maximal DF was 110.87 ± 12.97 deg in the pre-osteotomy state. Removal of a 7.5 mm wedge improved DF by 8 deg to a mean 102.93 ± 13.81 deg (p = 0.08). Removal of a 15 mm wedge improved DF by 16 deg to a mean 95.96 ± 11.41 deg (p = 0.003). Cohen's d and effect size calculation demonstrated a 7.5 mm wedge to have a small effect on DF, while a 15 mm wedge had a medium effect (0.29, 0.52 respectively). Maximal PF did not change significantly amongst the pre-osteotomy, 7.5 mm wedge, or 15 mm wedge positions. ICC was 0.96. CONCLUSION: Based on the results presented in this study, removal of a 15 mm wedge with ZO yields significant and greater improvement in ROM than a 7.5 mm wedge. We hope the current study will better inform preoperative planning for ZO. STUDY TYPE: Prospective Cadaver Study. LEVEL OF EVIDENCE: V.

Evaluation of porcine decomposition and total body score (TBS) in a central European temperate forest.

The total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the porcine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one "substantial agreement" category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic casework in comparable contexts in Central Europe.

Solving the inverse problem of post-mortem interval estimation using Bayesian Belief Networks.

Bayesian Belief Networks (BBNs) can be applied to solve inverse problems such as the post-mortem interval (PMI) by a simple and logical graphical representation of conditional dependencies between multiple taphonomic variables and the observable decomposition effect. This study is the first cross-comparison retrospective study of human decomposition across three different geographical regions. To assess the effect of the most influential taphonomic variables on the decomposition rate (as measured by the Total Decomposition Score (TDS)), decomposition data was examined from the Forensic Anthropology Research Facility at the University of Tennessee (n = 312), the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 250), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 81). Two different BBNs for PMI estimations were created from the US and the UK training data. Sensitivity analysis was performed to identify the most influential parameters of TDS variance, with weaker variables (e.g., age, sex, clothing) being excluded during model refinement. The accuracy of the BBNs was then compared by additional validation cases: US (n = 28) and UK (n = 10). Both models conferred predictive power of the PMI and accounted for the unique combination of taphonomic variables affecting decomposition. Both models had a mean posterior probability of 86% (US) and 81% (UK) in favor of the experimental hypothesis (that the PMI was on, or less than, the prior last known alive date). Neither the US nor the UK datasets represented any cases below 'moderate' support for the value of PMI evidence. By applying coherent probabilistic reasoning to PMI estimations, one logical solution is provided to model the complexities of human decomposition that can quantify the combined effect of several uncertainties surrounding the PMI estimation. This approach communicates the PMI with an associated degree of confidence and provides predictive power on unknown PMI cases.

A retrospective comparative study to evaluate the reliability of post-mortem interval sources in UK and US medico-legal death investigations.

Post-mortem interval (PMI) information sources may be subject to varying degrees of reliability that could impact the level of confidence associated with PMI estimations in forensic taphonomy research and in the practice of medico-legal death investigation. This study aimed to assess the reliability of PMI information sources in a retrospective comparative analysis of 1813 cases of decomposition from the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 1714), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 99). PMI information sources were subjected to a two-stage evaluation using an adapted version of the 3x5 aspects of the UK police National Intelligence Model (NIM) to determine the confidence level associated with each source. Normal distribution plots were created to show the distribution frequency of the dependent variables (decomposition stage and source evaluation) by the independent variable of PMI. The manner, location, and season of death were recorded to ascertain if these variables influenced the reliability of the PMI. A confidence matrix was then created to assess the overall reliability and provenance of each PMI information source. Reliable PMI sources (including forensic specialists, missing persons reports, and digital evidence) were used across extensive PMI ranges (1 to 2920 days in the US, and 1 to 240 days in the UK) but conferred a low incidence of use with forensic specialists providing a PMI estimation in only 35% of all homicide cases. Medium confidence PMI sources (e.g., last known social contact) accounted for the majority of UK (54%, n = 54) and US (82%, n = 1413) cases and were associated with shorter PMIs and natural causes of death. Low confidence PMI sources represented the lowest frequencies of UK and US cases and exclusively comprised PMI information from scene evidence. In 96% of all cases, only one PMI source was reported, meaning PMI source corroboration was overall very low (4%). This research has important application for studies using police reports of PMI information to validate PMI estimation models, and in the practice of medico-legal death investigation where it is recommended that i) the identified reliable PMI sources are sought ii) untested or unreliable PMI sources are substantiated with corroborating PMI information, iii) all PMI sources are reported with an associated degree of confidence that encapsulates the uncertainty of the originating source.

Decomposition variability between the scene and autopsy examination and implications for post-mortem interval estimations.

Forensic experts rely on scene and/or autopsy photographs to estimate the post-mortem interval (PMI) when an in-situ assessment of decomposition is unfeasible. The degree of decomposition may vary between the scene and autopsy, which importantly could affect estimations of the unknown PMI in forensic casework. This study aimed to investigate decomposition variability between the scene and autopsy and assess the subsequent effect on the accuracy of PMI estimations. Scene and autopsy photographs from 94 cases with known PMI were used from the Allegheny County Office of the Medical Examiner in Pittsburgh, United States. The total decomposition scoring (TDS) method measured the overall decomposition level, and 28 markers of decomposition were recorded as a percentage of the total body surface area (TBSA). In 60% of cases the TDS had increased at autopsy causing significant overestimations of the autopsy PMI and 86% of decomposition markers varied between the scene and autopsy. Decomposition progressed during mortuary time lags (MTL) of 3-44 h, where bodies were stored in a pre-autopsy refrigerator at 4 °C, suggesting that refrigeration may not always delay decomposition. This research also assisted in validating photographs as a proxy for real-time decomposition assessments. While the autopsy photographs conferred higher quality than the scene photographs, the scene photographs produced more accurate PMI estimations. Forensic experts should exhibit caution when estimating the PMI from autopsy photographs alone, as they may not accurately reflect scene decomposition. To prevent misinterpretation of the PMI estimation, both scene and autopsy photographs should always be requested.

The effectiveness of forensic evidence in the investigation of volume crime scenes.

This study investigates the effectiveness of forensic evidence in UK volume crime investigations. The main aim was to identify characteristics of forensic evidence that influence its effectiveness in converting detections into criminal charges, as well as to critically consider the effectiveness of a recent service level agreement (SLA) implemented by Wiltshire Police, which aimed at reducing CSI attendance. The sample consisted of 445 police recorded cases received from Wiltshire Police. Presence or absence and location-related characteristics of fingerprint, DNA, and footwear evidence were evaluated on the effectiveness of forensic evidence and examined within the contexts of different volume crimes. Results showed a high level of correlation in converting detections into criminal charges where the presence of DNA, footwear, and multiple evidence types was recorded; and a positive correlation between forensic evidence ineffectiveness and presence of fingerprints, particularly in residential burglaries. Differences between individual offence types were expressed. The most prominent feature influencing the effectiveness of forensic evidence was found to be related to the movability of the exhibit associated with the recovered evidence, with DNA recovered from non-movable items presenting the strongest effectiveness. Cases processed after the implementation of the SLA did not show significant differences in forensic evidence effectiveness as compared to cases processed prior to the SLA, however, they demonstrated a lack in effectiveness of DNA evidence. The findings of the current research provide a better understanding of the contextual influences on the potential of forensic evidence and can support improvement of crime scene screening and CSI resource deployment.

Assessing the quality of footwear marks recovered from simulated graves.

Footwear marks are one of the most frequently encountered evidence types recovered from a crime scene and can provide valuable scene intelligence regarding potential suspects. It has been acknowledged that impressions of footwear and tools can be recovered from graves, but previous studies have only focused on tool mark recovery. This has led to a lack of published information regarding footwear mark recovery from graves. It is therefore important to demonstrate whether the recovery of footwear marks is feasible and, if so, under what conditions this can be achieved. To address recovery, this study, placed 60 three dimensional (3D) impressions of footwear marks within 60 simulated graves. This was done to assess time (1, 2, 4 months) and at known depths (20, 30, 40 cm). The footwear marks within the graves were covered with clothing or left uncovered. The shoe's design patterns were grouped and counted in a photographic comparison between the 3D footwear impressions, placed within the test-pits, and any recovered impressions. A grading system was adapted by the authors to score the quality of footwear impressions observed during recovery. The results demonstrate that the preservation and recovery of footwear impressions from graves is feasible. The simulated graves covered with clothing showed better preservation of footwear impressions, but there was no clear evidence that time or depth had an effect. The authors note that careful consideration and vigilant excavation skills are needed when excavating graves which may bear potential footwear marks, as their recovery will lead to an increased amount of intelligence that can link suspects to homicide scenes.

The effect of seasonality on the application of accumulated degree-days to estimate the early post-mortem interval.

This study investigated the effect of seasonal variables on decomposition in the early post-mortem period using 26 donated human cadavers at the University of Tennessee's Anthropology Research Facility (ARF), USA. The rate and pattern of decomposition in human cadavers (as measured by TBS and the revised TBSsurf methods) did not vary significantly between all seasons. Summer and autumn cadavers had comparable rates of accelerated decomposition despite significant differences in both ADD and temperature (p<0.05). Spring cadavers had the slowest onset of decomposition characteristics, even compared to the few decomposition characteristics expressed in winter. Seasonal variation in humidity, rather than temperature, may be the overarching driving force for decomposition progression in the early post-mortem period. Both TBS and TBSsurf methods were poor predictors of the PMI (R2=0.4) and significantly over-estimated the PMI across all seasons, although to a lesser extent in spring. This study also demonstrated no relationship between known ADD and TBS/TBSsurf (R2=0.025). TBS and TBSsurf are ADD-based PMI estimation models that cannot be validated under experimental conditions. Accounting for seasonal expression of individual decomposition characteristics is needed for improvement of PMI predictability in forensic practice.