Multimodality imaging reveals angiogenic evolution in vivo during calvarial bone defect healing.

The healing of calvarial bone defects is a pressing clinical problem that involves the dynamic interplay between angiogenesis and osteogenesis within the osteogenic niche. Although structural and functional vascular remodeling (i.e., angiogenic evolution) in the osteogenic niche is a crucial modulator of oxygenation, inflammatory and bone precursor cells, most clinical and pre-clinical investigations have been limited to characterizing structural changes in the vasculature and bone. Therefore, we developed a new multimodality imaging approach that for the first time enabled the longitudinal (i.e., over four weeks) and dynamic characterization of multiple in vivo functional parameters in the remodeled vasculature and its effects on de novo osteogenesis, in a preclinical calvarial defect model. We employed multi-wavelength intrinsic optical signal (IOS) imaging to assess microvascular remodeling, intravascular oxygenation (SO2), and osteogenesis; laser speckle contrast (LSC) imaging to assess concomitant changes in blood flow and vascular maturity; and micro-computed tomography (µCT) to validate volumetric changes in calvarial bone. We found that angiogenic evolution was tightly coupled with calvarial bone regeneration and corresponded to distinct phases of bone healing, such as injury, hematoma formation, revascularization, and remodeling. The first three phases occurred during the initial two weeks of bone healing and were characterized by significant in vivo changes in vascular morphology, blood flow, oxygenation, and maturity. Overall, angiogenic evolution preceded osteogenesis, which only plateaued toward the end of bone healing (i.e., four weeks). Collectively, these data indicate the crucial role of angiogenic evolution in osteogenesis. We believe that such multimodality imaging approaches have the potential to inform the design of more efficacious tissue-engineering calvarial defect treatments.

A Biomimetic Fibrous Composite Scaffold with Nanotopography-Regulated Mineralization for Bone Defect Repair.

The effective regeneration of large bone defects via bone tissue engineering is challenging due to the difficulty in creating an osteogenic microenvironment. Inspired by the fibrillar architecture of the natural extracellular matrix, we developed a nanoscale bioengineering strategy to produce bone fibril-like composite scaffolds with enhanced osteogenic capability. To activate the surface for biofunctionalization, self-adaptive ridge-like nanolamellae were constructed on poly(ε-caprolactone) (PCL) electrospinning scaffolds via surface-directed epitaxial crystallization. This unique nanotopography with a markedly increased specific surface area offered abundant nucleation sites for Ca2+ recruitment, leading to a 5-fold greater deposition weight of hydroxyapatite than that of the pristine PCL scaffold under stimulated physiological conditions. Bone marrow mesenchymal stem cells (BMSCs) cultured on bone fibril-like scaffolds exhibited enhanced adhesion, proliferation, and osteogenic differentiation in vitro. In a rat calvarial defect model, the bone fibril-like scaffold significantly accelerated bone regeneration, as evidenced by micro-CT, histological histological and immunofluorescence staining. This work provides the way for recapitulating the osteogenic microenvironment in tissue-engineered scaffolds for bone repair.

Bone flap binding and transposition: a method for bone reconstruction in cranial burst fractures and early-stage growing skull fractures.

PURPOSE: To introduce a method of cranial bone reconstruction for cranial burst fractures and early-stage growing skull fractures, named bone flap binding and transposition. METHODS: Cranial burst fractures, severe head injuries predominantly observed in infants, are characterized by widely diastatic skull fractures coupled with acute extracranial cerebral herniation beneath an intact scalp through ruptured dura mater. These injuries can develop into growing skull fractures. This study included two cases to illustrate the procedure, with a particular focus on the bone steps in managing these conditions. The medical history, clinical presentation, surgical procedures, and postoperative follow-up were retrospectively studied. The details of the surgical procedure were described. RESULTS: The method of bone reconstruction, named bone flap binding and transposition, was applied after the lacerated dural repair. Two bone pieces were combined to eliminate the diastatic bone defect and then fixed by an absorbable cranial fixation clip and bound by sutures. The combined bone flap was repositioned into the bone window, completely covering the area of the original dural laceration. Subsequently, the bone defect was transferred to the area of normal dura. The postoperative courses for the two infants were uneventful. Follow-up CT scans revealed new bone formation at the previous bone defect and no progressive growing skull fracture. The major cranial defects had disappeared, leaving only small residual defects at the corners of the skull bone window, which required further recovery and did not affect the solidity of the skull. CONCLUSION: Bone flap binding and transposition provide a straightforward, cost-effective, and reliable method for cranial bone reconstruction of cranial burst fractures and early-stage growing skull fractures. This method has taken full advantage of the small infant's dura osteogenic potential without the need for artificial or metallic bone repair materials. The effectiveness of the method needs further validation with more cases in the future.

The Uniform Distribution of Hydroxyapatite in a Polyurethane Foam-Based Scaffold (PU/HAp) to Enhance Bone Repair in a Calvarial Defect Model.

Polyurethane (PU) is a promising material for addressing challenges in bone grafting. This study was designed to enhance the bone grafting capabilities of PU by integrating hydroxyapatite (HAp), which is known for its osteoconductive and osteoinductive potential. Moreover, a uniform distribution of HAp in the porous structure of PU increased the effectiveness of bone grafts. PEG/APTES-modified scaffolds were prepared through self-foaming reactions. A uniform pore structure was generated during the spontaneous foaming reaction, and HAp was uniformly distributed in the PU structure (PU15HAp and PU30HAp) during foaming. Compared with the PU scaffolds, the HAp-modified PU scaffolds exhibited significantly greater protein absorption. Importantly, the effect of the HAp-modified PU scaffold on bone repair was tested in a rat calvarial defect model. The microstructure of the newly formed bone was analyzed with microcomputed tomography (µ-CT). Bone regeneration at the defect site was significantly greater in the HAp-modified PU scaffold group than in the PU group. This innovative HAp-modified PU scaffold improves current bone graft materials, providing a promising avenue for improved bone regeneration.

Skull and Scalp En-Bloc Harvest Protects Calvarial Perfusion: A Cadaveric Study.

BACKGROUND: Calvarial defects are severe injuries that can result from a wide array of etiologies. Reconstructive modalities for these clinical challenges include autologous bone grafting or cranioplasty with biocompatible alloplastic materials. Unfortunately, both approaches are limited by factors such as donor site morbidly, tissue availability, and infection. Calvarial transplantation offers the potential opportunity to address skull defect form and functional needs by replacing "like-with-like" tissue but remains poorly investigated. METHODS: Three adult human cadavers underwent circumferential dissection and osteotomy to raise the entire scalp and skull en-bloc. The vascular pedicles of the scalp were assessed for patency and perfused with color dye, iohexol contrast agent for computed tomography (CT) angiography, and indocyanine green for SPY-Portable Handheld Imager assessment of perfusion to the skull. RESULTS: Gross changes were appreciated to the scalp with color dye, but not to bone. CT angiography and SPY-Portable Handheld Imager assessment confirmed perfusion from the vessels of the scalp to the skull beyond midline. CONCLUSION: Calvarial transplantation may be a technically viable option for skull defect reconstruction that requires vascularized composite tissues (bone and soft tissue) for optimal outcomes.

Experimental Modeling of Cranial Injury and Defect Reconstruction Using Superconstructive Polymers (PEEK).

Experimental model of resection craniotomy with subsequent reconstruction of the defect with a polymer implant enables comprehensive assessment of functional and ultrastructural changes during replacement of the damaged tissue. Reconstruction of a skull defect was accompanied by transient motor disturbance in the acute period and did not cause functional disorders and neurological deficits in a delayed period. Histological examination of osteal and brain tissue revealed no pathological reactions that could be associated with the response to the chemical components of the implant.

In situ bone regeneration of large cranial defects using synthetic ceramic implants with a tailored composition and design.

The repair of large cranial defects with bone is a major clinical challenge that necessitates novel materials and engineering solutions. Three-dimensionally (3D) printed bioceramic (BioCer) implants consisting of additively manufactured titanium frames enveloped with CaP BioCer or titanium control implants with similar designs were implanted in the ovine skull and at s.c. sites and retrieved after 12 and 3 mo, respectively. Samples were collected for morphological, ultrastructural, and compositional analyses using histology, electron microscopy, and Raman spectroscopy. Here, we show that BioCer implants provide osteoinductive and microarchitectural cues that promote in situ bone regeneration at locations distant from existing host bone, whereas bone regeneration with inert titanium implants was confined to ingrowth from the defect boundaries. The BioCer implant promoted bone regeneration at nonosseous sites, and bone bonding to the implant was demonstrated at the ultrastructural level. BioCer transformed to carbonated apatite in vivo, and the regenerated bone displayed a molecular composition indistinguishable from that of native bone. Proof-of-principle that this approach may represent a shift from mere reconstruction to in situ regeneration was provided by a retrieved human specimen, showing that the BioCer was transformed into well-vascularized osteonal bone, with a morphology, ultrastructure, and composition similar to those of native human skull bone.

Pulsed radiofrequency energy device (PEAK plasmablade™) and CustomBone® Cranioplasty: an appealing surgical rendez-vous.

BACKGROUND: CustomBone® prosthesis is a widely recognized effective and successful technique for the reconstruction of cranial bone defects. Prior the cranioplasty implant, meticulous dissection within thick scar tissue is required. During this delicate surgical manoeuvre is vital to avoid damage to the skin flap itself and to the underlying cerebrovascular structures. We report our experience and potential applications of a novel, pulsed monopolar radiofrequency energy device (PEAK PlasmaBlade™, Medtronic plc). It reduced the incidence of post operativesubgaleal hematoma, the operative times and the intra operative blood loss following cranioplasty compared to the traditional scalpel and scissor dissection. METHODS: The authors present a one centre case series study to review the indications, safety and efficacy of the PEAK PlasmaBlade™ in adult patientsunderwent cranioplasty. Two surgical techniques for tissue dissection were compared: PEAK PlasmaBlade™ versus scalpel and scissor dissection (SSD). Treatment outcomes following each of these surgical approaches, relative to rate of post-operative subgalealhematoma formation, hospital admission, and operative times were compared. RESULTS: A total of 10 patients that had cranioplasty treatment were evaluated. In patients underwent scalp dissection with the PEAKPlasmaBlade™, we observed a reduction in the operative times, in the subgaleal hematoma formation and then in the hospital stay. CONCLUSION: PEAK PlasmaBlade™ revealed to be a safe and effective device in tissues dissection for cranioplasty implant. It provided reduction of the rate of subgaleal hematoma formation, operating times and less potential risk to damage cerebrovascular structures.

Development and global validation of a 1-week-old piglet head finite element model for impact simulations.

PURPOSE: Child head injury under impact scenarios (e.g. falls, vehicle crashes, etc.) is an important topic in the field of injury biomechanics. The head of piglet was commonly used as the surrogate to investigate the biomechanical response and mechanisms of pediatric head injuries because of the similar cellular structures and material properties. However, up to date, piglet head models with accurate geometry and material properties, which have been validated by impact experiments, are seldom. We aim to develop such a model for future research. METHODS: In this study, first, the detailed anatomical structures of the piglet head, including the skull, suture, brain, pia mater, dura mater, cerebrospinal fluid, scalp and soft tissue, were constructed based on CT scans. Then, a structured butterfly method was adopted to mesh the complex geometries of the piglet head to generate high-quality elements and each component was assigned corresponding constitutive material models. Finally, the guided drop tower tests were conducted and the force-time histories were ectracted to validate the piglet head finite element model. RESULTS: Simulations were conducted on the developed finite element model under impact conditions and the simulation results were compared with the experimental data from the guided drop tower tests and the published literature. The average peak force and duration of the guide drop tower test were similar to that of the simulation, with an error below 10%. The inaccuracy was below 20%. The average peak force and duration reported in the literature were comparable to those of the simulation, with the exception of the duration for an impact energy of 11 J. The results showed that the model was capable to capture the response of the pig head. CONCLUSION: This study can provide an effective tool for investigating child head injury mechanisms and protection strategies under impact loading conditions.

[Rare cases of head traumas incited by propeller blades of small vessels]. / Redkie sluchai travm golovy, prichinennykh lopastyami grebnykh vintov malomernykh sudov.

2 cases of death in males due to multiple head impacts by propeller blades of small vessels are given. The set of the following signs provides a basis for confirming the above-mentioned mechanism and properties of the traumatic object: multiplicity, oblong shape, parallel step-like arrangement of injury lengths, acute-angled M-shaped or Y-shaped injury ends, uneven edges, sometimes with the formation of small flaps and abrasion, lumpy wound walls, multi-fragmented nature of fractures in a limited area of the skullcap and facial skull bones, the location of damage to intracranial structures in the projection of external injuries and fractures of the cerebral skull bones.

Two peculiar cases of cranial fractures running through craniotomy burr holes: may this be a kind of "exception" to the Puppe rule.

A correct assessment on the position, path, and direction of fracture lines is crucial when the sequence of different injuries on the skull has to be ascertained. In this context, the so-called Puppe's rule on intersecting fracture lines has always been considered a cornerstone of such an investigation. However, there is one factor that has never been previously considered: how do fracture lines behave when they reach the edges of an old and remodeled hole from a previous craniotomy? Two peculiar cases are presented of subjects undergoing cranial fractures due to blunt force trauma (case 1) and gunshot (case 2). Both previously underwent neurosurgical operations with persistence of the burr holes produced by the craniotomy drill (15 and 20 years before death). What was arguable, according to Puppe's rule, was that the fracture lines, when at the edge of the craniotomy hole, stopped. However, what has been detected was different than what expected: fracture lines continued exactly in the opposite direction, as though they were "skipping" the hole, following the same direction and the same axis and stopping a few centimeters over on the opposite side of the craniotomy hole. Puppe's rule has never been refuted, but these cases are the closest to an exception ever seen in forensic anthropology.

Inter-group violence among early Holocene hunter-gatherers of West Turkana, Kenya.

The nature of inter-group relations among prehistoric hunter-gatherers remains disputed, with arguments in favour and against the existence of warfare before the development of sedentary societies. Here we report on a case of inter-group violence towards a group of hunter-gatherers from Nataruk, west of Lake Turkana, which during the late Pleistocene/early Holocene period extended about 30 km beyond its present-day shore. Ten of the twelve articulated skeletons found at Nataruk show evidence of having died violently at the edge of a lagoon, into which some of the bodies fell. The remains from Nataruk are unique, preserved by the particular conditions of the lagoon with no evidence of deliberate burial. They offer a rare glimpse into the life and death of past foraging people, and evidence that warfare was part of the repertoire of inter-group relations among prehistoric hunter-gatherers.

Extended Scalp Expansion for Larger Defects During Staged Cranioplasty.

BACKGROUND: Secondary cranioplasty is often required following trauma, infection, radiation, or oncologic care, but is complicated by soft-tissue deficits with limited regional options. Scalp tissue expanders can provide hair-bearing, vascularized tissue for tension- free closure yielding optimal aesthetic results. However, the upper limit of safe scalp expansion has not been explored. This study sought to evaluate the efficacy of extended scalp tissue expansion for challenging cranioplasties in a consecutive series. METHODS: Patients who underwent scalp tissue expansion before cranioplasty were retrospectively identified from a single institution between the years 2017 and 2020. Patient demographics, tissue expansion characteristics, and complications during expansion and after cranioplasty were collected. RESULTS: Six patients were identified who underwent staged scalp expansion for cranioplasty; 5 were male (83.3%) with a mean age of 43.8 ±â€Š12.5 years. Indications for cranioplasty included 2 epilepsy- related procedures, 1 oligodendroglioma, 2 infectious processes, and 1 traumatic incident. A single expander was used in 5 cases, whereas 2 were used in the remaining case. The average expander fill volume was 434.3 ±â€Š115 ccs with a mean expansion time of 3.3 ±â€Š1.4  months. Expander infection occurred in 1 case and expander exposure in another, but adequate scalp expansion was still achieved in both. Successful closure over cranioplasty was obtained in 5 cases (83.3%); 1 patient ultimately required free flap reconstruction for soft-tissue coverage. CONCLUSIONS: In cases of extended scalp defects, scalp tissue expansion remains the preferred method for recruiting large quantities of like tissue before implant cranioplasty.

Ballistic trauma caused by military rifles: experimental study based on synthetic skull proxies.

Rifles are often involved in violent deaths such as homicide and suicide. Consequently, expert knowledge and experimental forensic investigations are important to clarify the nature of ballistic trauma when applied to the human head and neurocranium. This study investigated differences in entrance wound morphology with Synbone® spheres which are described as being comparable to human flat bones. A series of ballistic experiments were conducted using two different rifle calibers (5.56 × 45 mm and 7.62 × 39 mm Full Metal Jacket (FMJ)). Synbone® spheres were used for close-range 0.3 m simulated executions as well as at 25 m and 35 m to simulate urban and military engagements. Results were compared with previously published experimental studies using similar military ammunition. In our study, entry wound morphology closely resembles real forensic cases compared to exit wound and overall shape morphology independently of the distance and the caliber. Circumferential delamination was clearly visible with full metal jacket (FMJ) rounds, yielding similar damage pattern morphology to the human crania. This study documented the presence of hydraulic burst or shock in all ten rounds from all three distances. Krönlein shots were also observed in some cases. Synbone® spheres constitute an acceptable synthetic surrogate for ballistic experiments. The present study offers new initial data on the behavior of Synbone® proxies in ballistic testing of military ammunitions; FMJ gunshot injuries to the human head, for distances that have not previously been published, suggesting that efficient tests can take place under these conditions. Further research on experimental ballistics with a larger number of controlled factors and multiple repetitions is recommended to verify the results of this pilot study before applied in forensic simulations.

Development of a Biomaterial Scaffold Integrated with Osteoinductive Oxysterol Liposomes to Enhance Hedgehog Signaling and Bone Repair.

Bone repair requires the tightly regulated control of multiple intrinsic and extrinsic cell types and signaling pathways. One of the positive regulatory signaling pathways in membranous and endochondral bone healing is the Hedgehog (Hh) signaling family. Here, a novel therapeutic liposomal delivery vector was developed by self-assembly of an Hh-activating cholesterol analog with an emulsifier, along with the addition of Smoothened agonist (SAG) as a drug cargo, for the enhancement of Hh signaling in bone regeneration. The drug-loaded nanoparticulate agonists of Hh signaling were immobilized onto trabecular bone-mimetic apatite-coated 3D scaffolds using bioinspired polydopamine adhesives to ensure favorable microenvironments for cell growth and local therapeutic delivery. Results showed that SAG-loaded liposomes induced a significant and dose-dependent increase in Hh-mediated osteogenic differentiation, as evidenced by in vitro analysis of bone marrow stromal cells, and in vivo calvarial bone healing, as evidenced using all radiographic parameters and histomorphometric analyses. Moreover, favorable outcomes were achieved in comparison to standards of care, including collagen sponge-delivered rBMP2 or allograft bone. In summary, this study demonstrates using a nanoparticle packaged Hh small molecule as a widely applicable bone graft substitute for robust bone repair.

Practical application of synthetic head models in real ballistic cases.

In shooting crimes, ballistics tests are often recommended in order to reproduce the wound characteristics of the involved persons. For this purpose, several "simulants" can be used. However, despite the efforts in the research of "surrogates" in the field of forensic ballistic, the development of synthetic models needs still to be improved through a validation process based on specific real caseworks. This study has been triggered by the findings observed during the autopsy performed on two victims killed in the same shooting incident, with similar wounding characteristics; namely two retained head shots with ricochet against the interior wall of the skull; both projectiles have been recovered during the autopsies after migration in the brain parenchyma. The thickness of the different tissues and structures along the bullets trajectories as well as the incident angles between the bullets paths and the skull walls have been measured and reproduced during the assemblage of the synthetic head models. Two different types of models ("open shape" and "spherical") have been assembled using leather, polyurethane and gelatine to simulate respectively skin, bone and soft tissues. Six shots have been performed in total. The results of the models have been compared to the findings of post-mortem computed tomography (PMCT) and the autopsy findings.Out of the six shots, two perforated the models and four were retained. When the projectile was retained, the use of both models allowed reproducing the wounds characteristics observed on both victims in terms of penetration and ricochet behaviour. However, the projectiles recovered from the models showed less deformation than the bullets collected during the autopsies. The "open shape" model allowed a better controlling on the shooting parameters than the "spherical" model. Finally, the difference in bullet deformation could be caused by the choice of the bone simulant, which might under-represent either the strength or the density of the human bone. In our opinion, it would be worth to develop a new, more representative material for ballistic which simulates the human bone.

Fake gunshot wounds in the skull-post-mortem artifact caused by steel probe during police search for a missing body.

The paper presents a case of a forensic autopsy of a young woman who was murdered and her dismembered body was hidden in soil and water. In the skull of the deceased, in the temporal and occipital regions, the autopsy revealed 3 round, almost identical holes, which looked like small caliber gunshot wounds. Doubts about the cause of these injuries were raised by the fact that despite the decomposition of the body, the continuity of the dura at the site of these holes remained undamaged and the absence of any trace of a bullet's wound track in the brain, the absence of a foreign body in the cranial cavity, as well as the absence of wounds on the opposite side of the skull that could be exit wounds. A thorough analysis of the investigation and the activities carried out during the search for the missing body allowed to adopt and finally confirm the hypothesis that the above mentioned skull damage occurred during the search for the cut-off head of the deceased in shallow water by means of special tapered conical steel probes used by the rescue/search teams. Due to the structure of such a spike, i.e., a sharp end and then a wide cone, only a superficial puncture of the steel probe tip three times into the skull had taken place, which caused regular, rounded bone damage without damaging the dura and brain. The presented case indicates that sometimes post-mortem artifacts may suggest a completely different origin of wounds, which emphasizes the need for a comprehensive analysis of all possible causes of their occurrence, particularly data concerning the handling of the corpse before it is delivered to the morgue, so as not to make a diagnostic error during autopsy.

Sharp force trauma with two katana swords: identifying the murder weapon by comparing tool marks on the skull bone.

This paper describes the variety of information that a tool mark analysis on human tissue can provide based on a case of multiple sharp violence. The perpetrator attacked the victim with a sharp-edged weapon against the head, leaving several deep wounds on the back of the skull bone. Three of those marks on the skull bone could be used for a forensic tool mark examination. Silicone casts of the marks were compared by light microscopy with casts of test marks of Japanese katana swords found at the crime scene. One of the swords could be identified as the one responsible for the marks. In addition, the marks and the test marks were scanned in 3D and examined in a visual on-screen comparison confirming the results from the light microscopic examination. Furthermore, a mathematical approach in which the signatures of the marks from the skull bone and the test marks from the sword were compared by cross correlation confirms those findings. In addition, the aforementioned results were used to determine the orientation of the sword in relation to the cranial bone at the time of the respective impact.

Prevalence of cranial trauma in Eurasian Upper Paleolithic humans.

OBJECTIVES: This study characterizes patterns of cranial trauma prevalence in a large sample of Upper Paleolithic (UP) fossil specimens (40,000-10,000 BP). MATERIALS AND METHODS: Our sample comprised 234 individual crania (specimens), representing 1,285 cranial bones (skeletal elements), from 101 Eurasian UP sites. We used generalized linear mixed models (GLMMs) to assess trauma prevalence in relation to age-at-death, sex, anatomical distribution, and between pre- and post-Last Glacial Maximum (LGM) samples, while accounting for skeletal preservation. RESULTS: Models predicted a mean cranial trauma prevalence of 0.07 (95% CI 0.003-0.19) at the level of skeletal elements, and of 0.26 (95% CI 0.08-0.48) at the level of specimens, each when 76-100% complete. Trauma prevalence increased with skeletal preservation. Across specimen and skeletal element datasets, trauma prevalence tended to be higher for males, and was consistently higher in the old age group. We found no time-specific trauma prevalence patterns for the two sexes or age cohorts when comparing samples from before and after the LGM. Samples showed higher trauma prevalence in the vault than in the face, with vault remains being affected predominantly in males. DISCUSSION: Cranial trauma prevalence in UP humans falls within the variation described for Mesolithic and Neolithic samples. According to our current dataset, UP males and females were exposed to slightly different injury risks and trauma distributions, potentially due to different activities or behaviors, yet both sexes exhibit more trauma among the old. Environmental stressors associated with climatic changes of the LGM are not reflected in cranial trauma prevalence. To analyze trauma in incomplete skeletal remains we propose GLMMs as an informative alternative to crude frequency calculations.

The character of conflict: A bioarchaeological study of violence in the Nasca highlands of Peru during the Late Intermediate Period (950-1450 C.E.).

OBJECTIVES: This study uses osteological and radiocarbon datasets combined with formal quantitative analyses to test hypotheses concerning the character of conflict in the Nasca highlands during the Late Intermediate Period (LIP, 950-1450 C.E.). We develop and test osteological expectations regarding what patterns should be observed if violence was characterized by intragroup violence, ritual conflict, intermittent raiding, or internecine warfare. MATERIALS AND METHODS: Crania (n = 267) were examined for antemortem and perimortem, overkill, and critical trauma. All age groups and both sexes are represented in the sample. One hundred twenty-four crania were AMS dated, allowing a detailed analysis of diachronic patterns in violence among various demographic groups. RESULTS: Thirty-eight percent (102/267) of crania exhibit some form of cranial trauma, a significant increase from the preceding Middle Horizon era. There are distinct trauma frequencies within the three subphases of the LIP, but Phase III (1300-1450 C.E.) exhibits the highest frequencies of all trauma types. Males exhibit significantly more antemortem trauma than females, but both exhibit similar perimortem trauma rates. DISCUSSION: There was chronic, internecine warfare throughout the Late Intermediate Period with important variations in violence throughout the three temporal phases. Evidence for heterogeneity in violent mortality shows a pattern consistent with social substitutability, whereby any and all members of the Nasca highland population were appropriate targets for lethal and sublethal violence. We argue that by testing hypotheses regarding the targets and types of conflict we are better able to explain the causes and consequences of human conflict.