Intact Human Cadavers Research Articles

A cadaveric study on superior hypogastric plexuses

Introduction: The superior hypogastric plexus (SHP) is found around the level of aortic bifurcation. It is important in surgical procedures in the pelvis.Methods: Ten (5; M & 5; F) fresh intact adult human cadavers were dissected. Following the initial dissection, all of them were further sectioned sagittal in the midline and separated in to half pelvises, and assessed. The study was carried out in the Department of Anatomy, Faculty of medicine Ragama, Sri Lanka from 2022 to 2024. The ethical clearance was obtained.Results: In all specimens, left connecting fibers from the inferior mesenteric plexuses (IMA) crossed the left common iliac artery and joining to the superior hypogastric plexuses. In 80%, right connecting nerve fibers from the inferior mesenteric plexuses crossed the right common iliac artery and joined the superior hypogastric plexus (SHP). Eighty percent of the specimens had, well-defined nerve strands, whereas 20% contained a delicate and irregular meshwork. In all of the specimens, the median root, or a nerve root from abdominal aortic plexus from the IMA were present. In 80% specimens, the SHP was located between the aortic bifurcation and the sacral promontory. In 20%, it extended across the pelvic brim and ended on the body of the S1 vertebra.Conclusion: The majority of the SHP were located below the aortic bifurcation and had well-defined nerve strands, rest traversed the pelvic brim and terminated on the body of the S1 vertebra. Further larger sample studies are recommended.

Cadaveric biomechanical testing of torque - to - failure magnitude of Bilateral Apical Vertebral Derotation maneuver in the thoracic spine.

It remains unclear what is the real safe limit of torque magnitude during Bilateral Apical Vertebral Derotation (BAVD) in thoracic curve correction. Up to author’s knowledge there is no study except this one, to reproduce in–vivo real measurements and intraoperative conditions during BAVD maneuver. The objective of this study was to evaluate the torsional strength of the instrumented thoracic spine under axial rotation moment as well as to define safety limits under BAVD corrective maneuver in scoliosis surgery. 10 fresh, full-length, young and intact human cadavers were tested. After proper assembly of the apparatus, the torque was applied through its apical part, simulating thoracic curve derotation. During each experiment the torque magnitude and angular range of derotation were evaluated. For more accurate analysis after every experiment the examined section of the spine was resected from the cadaver and evaluated morphologically and with a CT scan. The average torque to failure during BAVD simulation was 73,3 ± 5,49Nm. The average angle of BAVD to failure was 44,5 ± 8,16°. The majority of failures were in apical area. There was no significant difference between the fracture occurrence of left or right side of lateral wall of the pedicle. There was no spinal canal breach and/or medial wall failure in any specimen. The safety limits of thoracic spine and efficacy of BAVD for axial plane correction in the treatment of Adolescent Idiopathic Scoliosis (AIS) were established. It provided qualitative and quantitative information essential for the spinal derotation under safe loading limits.

Anatomic relationship between the spermatic cord and the pubic tubercle: are our clamps injuring the cord during symphyseal repair?

Traditional repair of the disrupted pubic symphysis includes application of pointed clamps to the pubic tubercles and/or pubic body for fracture reduction. Recent studies have reported rates of sexual dysfunction of 42%-90% after repair of these injuries. The purpose of this study is to define the anatomy of the spermatic cord relative to the pubic tubercle and other local structures to assess the risk of sustaining an iatrogenic injury during clamp placement. Eight intact lower-half fresh male human cadavers were dissected. A window of skin and subcutaneous tissue was excised to expose the low abdominal wall and penile root. Pubic tubercles were identified by palpation and marked. The spermatic cord was identified at the superficial inguinal ring and followed into the scrotum, and any anatomical abnormalities were recorded. The relationship and distance of the spermatic cord to the pubic tubercle, insertion of the inguinal ligament and abdominal wall musculature, and pubic symphysis were recorded. Photographs were taken of the superficial and deep anatomy. Spermatic cords were found to follow a consistent course after exiting the inguinal canal at the lower abdomen: they coursed inferior and medial to a position lateral to the pubic tubercles. In all cases, the spermatic cord lay adjacent, directly lateral to the tubercle with an average separation of 0.8 mm (range, 0-2 mm). The average distances from the lateral aspect of the tubercle and the medial border of the spermatic cord to the pubic symphysis were 26 and 27 mm, respectively. Qualitatively, even with direct visualization, it was not feasible to apply a pointed tenaculum to the pubic tubercles without piercing the spermatic cord, unless one manually retracted the latter. The spermatic cord is located lateral and immediately adjacent to the pubic tubercle after it exits the inguinal canal and passes into the scrotum. As such, the spermatic cord seems to be at a significant risk of sustaining injury when pointed forceps are placed on the tubercles, as is often recommended during the repair of pubic diastasis.

Sustained Combustion of Bodies: Some Observations*

Previous tests have explored the fire effects and fuel characteristics of animal carcasses in intense fires of relatively short duration. Here, test fires were conducted involving intact human cadavers and torsos that included nonaccelerated, long-duration fires involving the bedding and clothing (in the manner of typical accidental deaths). The objective was to observe the fire conditions (size, radiant heat flux, and duration), where a human body represented the major fuel package in a nonaccelerated fire. The pattern of damage to the body was documented and compared with that resulting from a furnished room fire. Two intact, unembalmed human cadavers were exposed to fires of simulated accidental origin. The bedding was ignited by an open flame, and the fires were allowed to burn unaided to self-extinguishment. It was found that normal human bodies can support a modest-sized fire for some 6-7 h under these conditions. The presence of a substrate material that can act as a wick for the combustion of the rendered body fat results in extensive destruction of the torso where the greatest amount of subcutaneous fat resides, with less damage to the head and limbs. A third (partial) cadaver was exposed to a recreation of a typical accidental fire in a furnished room that progressed to full room involvement. This fire of some 15 min of total duration inflected only surface-layer damage to the torso of the victim.

Trabecular Bone Structure Analysis in the Osteoporotic Spine Using a Clinical In Vivo Setup for 64-Slice MDCT Imaging: Comparison to μCT Imaging and μFE Modeling

Assessment of trabecular microarchitecture may improve estimation of biomechanical strength, but visualization of trabecular bone structure in vivo is challenging. We tested the feasibility of assessing trabecular microarchitecture in the spine using multidetector CT (MDCT) on intact human cadavers in an experimental in vivo-like setup. BMD, bone structure (e.g., bone volume/total volume = BV/TV; trabecular thickness = Tb.Th; structure model index = SMI) and bone texture parameters were evaluated in 45 lumbar vertebral bodies using MDCT (mean in-plane pixel size, 274 microm(2); slice thickness, 500 microm). These measures were correlated with structure measures assessed with microCT at an isotropic spatial resolution of 16 microm and to microfinite element models (microFE) of apparent modulus and stiffness. MDCT-derived BMD and structure measures showed significant correlations to the density and structure obtained by microCT (BMD, R(2) = 0.86, p < 0.0001; BV/TV, R(2) = 0.64, p < 0.0001; Tb.Th, R(2) = 0.36, p < 0.01). When comparing microCT-derived measures with microFE models, the following correlations (p < 0.001) were found for apparent modulus and stiffness, respectively: BMD (R(2) = 0.58 and 0.66), BV/TV (R(2) = 0.44 and 0.58), and SMI (R(2) = 0.44 and 0.49). However, the overall highest correlation (p < 0.001) with microFE app. modulus (R(2) = 0.75) and stiffness (R(2) = 0.76) was achieved by the combination of QCT-derived BMD with the bone texture measure Minkowski Dimension. In summary, although still limited by its spatial resolution, trabecular bone structure assessment using MDCT is overall feasible. However, when comparing with microFE-derived bone properties, BMD is superior compared with single parameters for microarchitecture, and correlations further improve when combining with texture measures.

Feasibility of Measuring Trabecular Bone Structure of the Proximal Femur Using 64-Slice Multidetector Computed Tomography in a Clinical Setting

We studied the feasibility of cancellous bone structure assessment of the proximal femur using multidetector computed tomography (MDCT) in an simulated in vivo experimental model. The proximal femur of 15 intact human cadavers was examined using 64-row MDCT using a thin-section protocol with an in-plane spatial resolution of 273 mum. High-resolution peripheral quantitative computed tomography (HR-pQCT) of the isolated specimens with a voxel size of 82 mum served as a standard of reference. Trabecular bone structure and optimized textural parameters were calculated in MDCT images and compared to measures obtained by HR-pQCT. Significant correlations between MDCT- and HR-pQCT-derived values for bone fraction (r = 0.87), trabecular separation (r = 0.66), and number (r = 0.53) were found. Parameters derived from textural analysis performed better in predicting trabecular separation (up to r = 0.86) and number (up to r = 0.83). Trabecular thickness could not be quantified correctly using MDCT, most likely due to its limited resolution. Individual parameters for assessement of trabecular microarchitecture can be measured using MDCT-derived imaging studies and a simulated in vivo setup. Thus, in vivo assessment of bone architecture in addition to BMD may be feasible in clinical practice.

Stereotactic CT-guided Percutaneous Stabilization of Posterior Pelvic Ring Fractures: A Preclinical Cadaver Study

To determine the accuracy of frameless stereotactic computed tomographic (CT)-guided wire placement for percutaneous fixation of posterior pelvic ring fractures in human cadavers. Four intact human cadavers were fixated in a double-vacuum immobilization system. A 2.5-mm helical CT dataset was obtained and transferred to the three-dimensional (3D) navigation system. In every specimen, two paths on each side (total number, 16) were defined on multiplanar reconstructions of the 3D CT datasets, simulating fixation of the iliosacral joint. An aiming device was adjusted according to the plan, and a 2.5-mm pin was advanced through the aiming device to the precalculated target point. To determine the accuracy of pin placement, a control CT scan was co-registered to the planning CT scan (with the planned trajectories). The distance between the planned and achieved positions of the pins (3D accuracy) was calculated in millimeters. The mean 3D accuracy was 1.84 mm +/- 0.9 (standard deviation) at the bone entrance point and 2.5 mm +/- 1.2 at the target, as determined with image fusion between the planning CT scan and the control CT scan with the pins in place. The described technique enables accurate placement of pins in the pelvis and may be useful for percutaneous orthopedic procedures.

Instantiation and registration of statistical shape models of the femur and pelvis using 3D ultrasound imaging

Statistical shape modelling potentially provides a powerful tool for generating patient-specific, 3D representations of bony anatomy for computer-aided orthopaedic surgery (CAOS) without the need for a preoperative CT scan. Furthermore, freehand 3D ultrasound (US) provides a non-invasive method for digitising bone surfaces in the operating theatre that enables a much greater region to be sampled compared with conventional direct-contact (i.e., pointer-based) digitisation techniques. In this paper, we describe how these approaches can be combined to simultaneously generate and register a patient-specific model of the femur and pelvis to the patient during surgery. In our implementation, a statistical deformation model (SDM) was constructed for the femur and pelvis by performing a principal component analysis on the B-spline control points that parameterise the freeform deformations required to non-rigidly register a training set of CT scans to a carefully segmented template CT scan. The segmented template bone surface, represented by a triangulated surface mesh, is instantiated and registered to a cloud of US-derived surface points using an iterative scheme in which the weights corresponding to the first five principal modes of variation of the SDM are optimised in addition to the rigid-body parameters. The accuracy of the method was evaluated using clinically realistic data obtained on three intact human cadavers (three whole pelves and six femurs). For each bone, a high-resolution CT scan and rigid-body registration transformation, calculated using bone-implanted fiducial markers, served as the gold standard bone geometry and registration transformation, respectively. After aligning the final instantiated model and CT-derived surfaces using the iterative closest point (ICP) algorithm, the average root-mean-square distance between the surfaces was 3.5mm over the whole bone and 3.7mm in the region of surgical interest. The corresponding distances after aligning the surfaces using the marker-based registration transformation were 4.6 and 4.5mm, respectively. We conclude that despite limitations on the regions of bone accessible using US imaging, this technique has potential as a cost-effective and non-invasive method to enable surgical navigation during CAOS procedures, without the additional radiation dose associated with performing a preoperative CT scan or intraoperative fluoroscopic imaging. However, further development is required to investigate errors using error measures relevant to specific surgical procedures.

Self-calibrating 3D-ultrasound-based bone registration for minimally invasive orthopedic surgery

Intraoperative freehand three-dimensional (3-D) ultrasound (3D-US) has been proposed as a noninvasive method for registering bones to a preoperative computed tomography image or computer-generated bone model during computer-aided orthopedic surgery (CAOS). In this technique, an US probe is tracked by a 3-D position sensor and acts as a percutaneous device for localizing the bone surface. However, variations in the acoustic properties of soft tissue, such as the average speed of sound, can introduce significant errors in the bone depth estimated from US images, which limits registration accuracy. We describe a new self-calibrating approach to US-based bone registration that addresses this problem, and demonstrate its application within a standard registration scheme. Using realistic US image data acquired from 6 femurs and 3 pelves of intact human cadavers, and accurate Gold Standard registration transformations calculated using bone-implanted fiducial markers, we show that self-calibrating registration is significantly more accurate than a standard method, yielding an average root mean squared target registration error of 1.6 mm. We conclude that self-calibrating registration results in significant improvements in registration accuracy for CAOS applications over conventional approaches where calibration parameters of the 3D-US system remain fixed to values determined using a preoperative phantom-based calibration.

Strain gauge biomechanical evaluation of forces in orbital floor fractures.

Since the first description of orbital blow-out fractures, there has been much confusion as to their aetiology. Two principal mechanisms have been proposed to explain these fractures, the buckling and hydraulic mechanisms, caused by trauma to the orbital rim and the globe of the eye, respectively. Previous experimental and clinical studies have aimed to support one or other of these two theories. However, these studies have failed to provide quantifiable data to objectively support their conclusions. We present the results of a study of these two proposed mechanisms under identical conditions, using quantifiable intraocular pressure, variable and quantifiable force, and quantifiable bone strain distribution with strain gauge analysis in fresh intact human post-mortem cadavers. Both qualitative and quantitative findings suggest that efforts to establish one theory over the other as the primary mechanism have been misplaced. Both mechanisms produce orbital floor fractures, although these fractures differ fundamentally in their size and location. We have objectively demonstrated that it is easier to fracture the orbital floor by the hydraulic mechanism than by the buckling mechanism, and provided quantitative data for the average force required to displace the orbital floor.

Selective retrosigmoid vestibular neurectomy without internal auditory canal drill-out: an anatomic study.

It is well established that selective vestibular nerve section by means of the retrosigmoid or posterior fossa approach can be accomplished with or without drill-out of the internal auditory canal (IAC) by virtue of the presence or absence of a surgically accessible cleavage plane between the vestibular and cochlear nerves. Some reports have indicated that a majority of patients would be amenable to successful separation of the vestibular nerve from the cochlear nerve medial to the IAC, thus obviating the need for IAC drill-out and associated complications. However, other reports have indicated routine difficulty in finding a satisfactory vestibulocochlear cleavage plane within the cerebellopontine angle. This in situ cadaver study was undertaken to determine whether normal anatomic relationships support the hypothesis that selective vestibular nerve section can be accomplished by means of the posterior fossa approach without the need for concomitant IAC drill-out in a majority of circumstances. A retrosigmoid approach to the posterior fossa was performed bilaterally on 36 intact human cadavers. After displacement of the cerebellum, an operating surgical microscope was used to visualize the cerebellopontine angle in the surgical position. The ability to develop a satisfactory cleavage plane between the vestibular and cochlear nerves without the need for drill-out of the IAC was established in each case. Seventy-two vestibulocochlear nerve bundles in 36 intact human cadavers were analyzed. A vestibulocochlear nerve cleavage plane within the cerebellopontine angle amenable to neurectomy medial to the porus of the IAC was observed in 81% left and 69% right vestibulocochlear nerve bundles (average, 75%). The facial nerve was found deep or anterior to the vestibulocochlear nerve bilaterally in all cases examined. The anterior inferior cerebellar artery, or a branch of the artery, was found to cross the plane between the facial and vestibulocochlear nerve bundles within the lateral cerebellopontine angle in 47% of the cases on the left and in 50% of cases on the right. A vestibulocochlear nerve cleavage plane amenable for selective vestibular nerve transection without drilling the IAC was found in 75% of the 72 cerebellopontine angles studied. The facial nerve consistently lies deep or anterior to the vestibulocochlear nerve within the cerebellopontine angle with the retrosigmoid approach. These findings support the rational and feasibility of avoiding drill-out of the IAC in the majority of circumstances when performing selective vestibular neurectomy by means of the posterior fossa approach for Ménière's syndrome and other vestibular disorders.

Plantar impact causing midfoot fractures result in higher forces in Chopart's joint than in the ankle joint

Purpose. Force effect (impact, extent of foot compartment deformation) and result (fracture pattern) for midfoot fractures in car occupants is known. An analysis of the processes in the foot was intended to improve car safety. Materials and methods. Eleven fresh, unfrozen, unpreserved intact human cadavers (age: 36.8 (16–61) years, gender: male, race: Caucasian) were studied 24–72 h after death. In 3 cadavers (5 feet) the experimental design was established: entire cadaver fixed on a special tray in supine position, pendulum with bar impactor hitting the foot plantar to Lisfranc's joint. A custom-made pressure sensor was inserted in the ankle (A), talonavicular (TN) and calcaneocuboid (CC) joints (resolution: 1 cm 2 , sampling rate: 500/s). Results. Sixteen feet were measured; midfoot fractures were induced in 11 feet. The maximum pressure amounted to 1.22–2.55 MPa (2.04±0.412) at 0.005–0.195 s (0.067±0.059) after impact. The maximum pressure occurred in 8 (50%) cases in the ankle, in 7 (44%) of the TN and 1 (6%) of the CC joints. A comparison of the first 200 pressure samples after impact of all sensor fields resulted in higher forces in Chopart's joint than in the ankle ( t-test: p<0.001). These force differences were higher in cases with midfoot fractures (mixed model analysis of variance: p=0.003). Conclusion. Due to considerable forces in Chopart's joint we recommend a modification of the actual crash test dummy lower extremity model with an additional load cell that detects forces in the longitudinal direction of the foot axis.

Non-Invasive Monitoring of Acute Intracranial Mass Lesions Using Ultrasonic Fingerprinting

ABSTRACTPotentially dangerous neurological changes in shock-trauma patients are currently monitored by computer-aided X-ray tomography which is prohibitively expensive and even dangerous for long-term, e.g., comatose, patients. By ultrasound, only low-frequency “diffuse” ultrasonic inspection is feasible through the skull so that the details are irreversible lost in the essentially random scattering process. In order to overcome this inherent limitation, we adapted a continuous computer-controlled ultrasonic monitoring system based on the ultrasonic fingerprinting method originally developed for materials characterization purposes in the nuclear, civil engineering, and aerospace industries. An ultrasonic detector directed at the general area of interest can be used to record and repeatedly update the personal signature of the patient, which is then used as an “ultrasonic fingerprint.” Any abrupt change in this signature indicates the immediate need for further investigation by CT or other sophisticated diagnostic tools. Experimental studies were conducted on both a human skull/gelatin phantom and 5 intact human cadavers. Ultrasonic fingerprinting could detect the secondary effects of volumetric changes occurring at multiple locations and the average detectable volumes of mass lesions were found to be lower than indications for surgical intervention.

Elastic deformation characteristics of the spine

A survey of some of the significant contributions in the area of experimental studies on the strength of the vertebral column is made. A short history on the experimental work with intact human cadavers is then given, leading to a discussion on the significance of bending stresses in the vertebral column during caudocephalad acceleration. Statistical data are presented to demonstrate this bending phenomenon. Justification of the use of embalmed cadaver material is provided in the form of a comparative investigation of fresh and embalmed vertebral segments under dynamic loading.