The use of spleen biomechanics in forensic pathology.

Forensic tissue mechanics applies biomechanical analyses of human tissues to support forensic investigations, including time since death estimation. Unlike temperature-based methods such as the Henssge nomogram, which are limited once thermal equilibrium is reached, rheological tissue analyses remain applicable at extended post-mortem intervals (PMIs). While previous studies have demonstrated the utility of human brain and liver tissue mechanics, the forensic relevance of splenic biomechanics has not yet been systematically explored. In this study, rheological properties of post-mortem human spleen tissue were investigated to assess their applicability for PMI estimation and routine forensic diagnostics. Spleen samples from 53 adult cadavers (PMI range 42-518 h) and four pediatric cases (PMI range 63-112 h) were collected during forensic autopsies and analyzed using oscillatory shear rheometry after standardized storage at 4 °C. Storage modulus, loss modulus, and complex shear modulus were correlated with PMI, demographic variables, spleen weight, resuscitation status, and histological features of tissue. The loss modulus exhibited a significant negative correlation with PMI, whereas storage and complex shear modulus did not. Receiver operating characteristic analysis demonstrated that a loss modulus threshold of 333 Pa provided strong confirmatory evidence for PMIs shorter than 200 h (AUC = 0.831; positive likelihood ratio = 12.75). No significant associations were observed between rheological parameters and age at death, sex, spleen weight, resuscitation attempts, or histological findings, indicating that these factors are unlikely to confound PMI-related biomechanical changes. These findings identify the loss modulus of splenic tissue as a sensitive and robust biomechanical marker for PMI estimation even at extended intervals. Splenic tissue mechanics therefore represent a valuable addition to the multimodal framework of forensic tissue mechanics, particularly for extended intervals, complementing established analyses of other organs.