Fresh-frozen Cadaver Research Articles

Qualitative and Quantitative Anatomy of the Humeral Attachment of the Pectoralis Major Muscle and Structures at Risk: A Cadaveric Study.

Background:Surgical pectoralis major (PM) repair can offer improved functional outcomes over nonoperative treatment. However, there is a lack of literature on consensus of the anatomical site of the humeral attachment.Purpose:To provide qualitative and quantitative anatomic analysis of the PM by focusing on humeral insertion and relevant structures at risk.Study Design:Descriptive laboratory study.Methods:Eight fresh-frozen male cadavers were dissected. The relevant landmarks that were collected and measured included (1) PM footprint length at the humeral insertion (total, sternal head, and clavicular head insertions); (2) PM tendon length from the humeral insertion to the musculotendinous junction; (3) distance from the PM humeral insertion to the lateral (LPN) and medial (MPN) pectoral nerves; and (4) distance from the coracoid process to the musculocutaneous nerve (MCN) in anatomical position.Results:The total PM footprint length was 81.4 mm (95% CI, 71.4-91.3). The sternal and clavicular heads that make up the PM had footprint lengths of 42.1 mm (95% CI, 32.9-51.4) and 56.6 mm (95% CI, 46.5-66.7), respectively. The PM tendon was wider at the clavicular head (74.7 mm; 95% CI, 67.5-81.7) than the sternal head insertions (43.0 mm; 95% CI, 40.1-45.9). The distances from the PM humeral insertion to LPN and MPN were 93.2 mm (95% CI, 83.1-103.3) and 103.8 mm (95% CI, 98.3-109.4), respectively. The coracoid process to MCN distance was 68.5 mm (95% CI, 60.2-76.8).Conclusion:This study successfully quantifies anatomic dimensions of the PM tendon, its sternal and clavicular head insertions, and its location relative to nearby vital structures. Such knowledge can provide surgeons with a better understanding of the PM in relation to nearby neurovascular structures during anatomic PM repair and reconstruction to avoid debilitating complications.Clinical Relevance:Knowledge of the quantitative anatomy of the PM at the humeral footprint along structures at risk may aid surgeons with identifying the injured part of the PM and improve outcomes for anatomic repair and reconstruction.

A cadaveric study of ulnar nerve strain at the elbow associated with cubitus valgus/varus deformity

BackgroundCubital tunnel syndrome can be caused by overtraction and dynamic compression in elbow deformities. The extent to which elbow deformities contribute to ulnar nerve strain is unknown. Here, we investigated ulnar nerve strain caused by cubitus valgus/varus deformity using fresh-frozen cadavers.MethodsWe used six fresh-frozen cadaver upper extremities. A strain gauge was placed on the ulnar nerve 2 cm proximal to the medial epicondyle of the humerus. For the elbow deformity model, osteotomy was performed at the distal humerus, and plate fixation was performed to create cubitus valgus/varus deformities (10°, 20°, and 30°). Ulnar nerve strain caused by elbow flexion (0–125°) was measured in both the normal and deformity models. The strains at different elbow flexion angles within each model were compared, and the strains at elbow extension and at maximum elbow flexion were compared between the normal model and each elbow deformity model. However, in the cubitus varus model, the ulnar nerve deflected more than the measurable range of the strain gauge; elbow flexion of 60° or more were considered effective values. Statistical analysis of the strain values was performed with Friedman test, followed by the Williams’ test (the Shirley‒Williams’ test for non-parametric analysis).ResultsIn all models, ulnar nerve strain increased significantly from elbow extension to maximal flexion (control: 13.2%; cubitus valgus 10°: 13.6%; cubitus valgus 20°: 13.5%; cubitus valgus 30°: 12.2%; cubitus varus 10°: 8.3%; cubitus varus 20°: 8.2%; cubitus varus 30°: 6.3%, P < 0.001). The control and cubitus valgus models had similar values, but the cubitus varus models revealed that this deformity caused ulnar nerve relaxation.ConclusionsUlnar nerve strain significantly increased during elbow flexion. No significant increase in strain 2 cm proximal to the medial epicondyle was observed in the cubitus valgus model. Major changes may have been observed in the measurement behind the medial epicondyle. In the cubitus varus model, the ulnar nerve was relaxed during elbow extension, but this effect was reduced by elbow flexion.

Suture Tape Augmentation for the Repair of Index Finger Radial Collateral Ligament Injury: A Biomechanical Study

Despite their clinical importance in maintaining the stability of the pinch mechanism, injuries of the radial collateral ligament (RCL) of the index finger may be underrecognized and underreported. The purpose of this biomechanical study was to compare the repair of index finger RCL tears with either a standard suture anchor or suture tape augmentation. The index fingers from 24 fresh-frozen human cadavers underwent repair of torn RCLs using either a standard suture anchor or suture tape augmentation. Following the repairs, the initial displacement of the repair with a 3-N ulnar deviating load was evaluated. Next, the change in displacement (cyclic deformation) of the repair after 1,000 cycles of 3 N of ulnar deviating force was calculated (displacement of the 1000th cycle- displacement of the first cycle). Finally, the amount of force required to cause clinical failure (30° ulnar deviation) of the repair was determined. Suture tape augmentation repairs displayed significantly less cyclic deformation (0.8± 0.5 mm) after cyclic loading than suture anchor repairs (1.8 ± 0.7 mm). There was no significant difference in the force required to cause the clinical failure of the repairs between the suture tape (35.1 ± 18.1 N) and suture anchor (24.5 ± 9.2 N) repairs. Index finger RCL repair with suture tape augmentation results in decreased deformation with repetitive motion compared with RCL repair alone. Suture tape augmentation may allow for early mobilization following index finger RCL repair by acting as a brace that protects the repaired ligament from deforming forces.

Creation of an incus recess for a middle-ear microphone using a drill or laser ablation: a comparison of equivalent noise level and middle ear transfer function

PurposeStudies have assessed the trauma and change in hearing function from the use of otological drills on the ossicular chain, but not the effects of partial laser ablation of the incus. A study of the effectiveness of a novel middle-ear microphone for a cochlear implant, which required an incus recess for the microphone balltip, provided an opportunity to compare methods and inform a feasibility study of the microphone with patients.MethodsWe used laser Doppler vibrometry with an insert earphone and probe microphone in 23 ears from 14 fresh-frozen cadavers to measure the equivalent noise level at the tympanic membrane that would have led to the same stapes velocity as the creation of the incus recess.ResultsDrilling on the incus with a diamond burr created peak noise levels equivalent to 125.1–155.0 dB SPL at the tympanic membrane, whilst using the laser generated equivalent noise levels barely above the baseline level. The change in middle ear transfer function following drilling showed greater variability at high frequencies, but the change was not statistically significant in the three frequency bands tested.ConclusionsWhilst drilling resulted in substantially higher equivalent noise, we considered that the recess created by laser ablation was more likely to lead to movement of the microphone balltip, and therefore decrease performance or result in malfunction over time. For patients with greatly reduced residual hearing, the greater consistency from drilling the incus recess may outweigh the potential benefits of hearing preservation with laser ablation.

Real-time assessment of anteroposterior stability of spinal segments

PurposeWhile anteroposterior instability of spinal segments is regarded as an important biomechanical aspect in the clinical evaluation of lumbar pathologies, the reliability of the available diagnostic tools is limited and an intraoperative method to quantify stability is lacking. The aim of this study was to develop and validate an instrument to measure the anteroposterior stability of a spinal segments in real-time.MethodsTorsi of five fresh-frozen human cadavers were used for this study. After pedicle screw insertion, a specifically modified reposition tool composed with load and linear sensors was used to measure the segmental anteroposterior motion caused by 100 N anterior and posterior force during 5 loading cycles on either side of the instrumentation by two different operators. The spinal segments were then resected from the torsi and anteroposterior loading with ± 100 N was repeated in an advanced biomechanical spine testing setup as a reference measurement. The Inter-correlation coefficient (ICC) was used for validation of the “intraoperative” device.ResultsInter-operator repeatability of the measurements showed an ICC of 0.93 (p < 0.0001) and the bilateral (left–right) comparison had an ICC of 0.73 (p < 0.0001). The ICC resulting from the comparison to the reference measurement was 0.82 (p < 0.0001) without offset correction, and 0.9 (p < 0.0001) with offset correction. The ICC converged at this value already after two of the five performed loading cycles.ConclusionAn accurate and reliable measurement tool is developed and validated for real-time quantification of anteroposterior stability of spinal segments and serves as a basis for future intraoperative use.

Is Human Vomeronasal Organ A Myth or A Neglected Structure?

The human vomeronasal organ (VNO) is a structure situated under the anteroinferior side of the nasal septum. It is mainly described in the rodents and found as a part of the accessory olfactory system. It has been shown to consist of specialized olfactory sensory cells, which function in perception of pheromones. With a large number of literature on the human VNO, there is little concensus of its persistence and functionality in human. During a routine dissection of nasal cavity, we recognized a one-sided vomeronasal pit in one of the six fresh-frozen cadavers (17 %) and described the position and structure of this rare structure morphologically. The present study summarizes the literature about the VNO and describes its structural and functional findings.

Evaluation of septal perforation size using a novel measuring device.

Nasal septal perforations can be managed with a septal button prosthesis. While they do not restore the physiological function of the septal mucosa, they are able to improve laminar nasal airflow. With the development of septal buttons sized specifically to perforations, accurate measurement of perforations has become more important for patient satisfaction and comfort. This task can be difficult to accomplish in the clinical setting. In this study, 2 new instruments developed to measure septal perforations were evaluated for accuracy and ease of use. Two types of measuring devices ("sizers") were created via 3D printing. One type included six serial, progressively sized instruments (serial sizers) and the other included two instruments with several size gradations (graded sizers). Septal perforations of varying sizes were surgically created in five fresh-frozen cadaver heads. Using a headlight and nasal speculum, 15 otolaryngology trainees and consultants were asked to measure the perforations (length × height) via four different methods: "eyeball" estimation, a ruler, the serial sizers, and the graded sizers. They were also asked to evaluate the methods themselves. An accurate measurement was defined as ± 1mm of the true measurement. A combination of Chi-square analysis and ANOVA was used to assess the accuracy and ease of use of the four methods. Chi-square analysis showed that the sizers were more accurate than the two traditional methods (eyeball and ruler) for measuring perforation length (73% vs. 44%, p = 4.8 × 10-7) and height (71% vs. 50%, p = 0.0003). ANOVA showed that the eyeball method overestimated perforation length significantly more than the other three methods (p = 0.002), and was also significantly less accurate than the other three methods (p < 0.001). Chi-square analysis did not show any correlation between participant training experience and measurement accuracy for any of the three methods. Participant comments and scores demonstrated a clear preference for the two sizers over the traditional methods. The two novel sizers studied here were significantly more accurate and easier to use than traditional methods for measuring nasal septal perforations. With broader implementation and study of these devices, there is potential to improve patient care surrounding septal perforations.

Accuracy and Safety of Non-Image Guided Trigger Finger Injections: A Cadaveric Study.

Stenosing flexor tenosynovitis is commonly treated by injection of corticosteroids into the flexor tendon sheath. However, there is no consensus in the literature regarding the optimal technique, specifically when not utilizing ultrasound guidance. Here, we present a cadaver study in which 3 common techniques of flexor sheath injection were compared with regard to their accuracy and safety profiles. Fifteen fresh-frozen cadaver hands (60 digits) were evenly divided into 3 groups (20 digits per group). Digits in each group were injected with methylene blue dye using 1 of the 3 techniques (palmar-to-bone, palmar supra-tendinous, and mid-axial). The fingers were then dissected and were inspected for location of dye, as well as injury to tendon or digital nerves. The mid-axial technique demonstrated the greatest accuracy with the highest rate of all intra-sheath injection, 15 of 20 digits (75%), while the palmar-to-bone technique produced the most combined intra- and extra-sheath injections, 13 of 20 digits, (65%) and the palmar supra-tendinous technique resulted in the most all extra-sheath injections, 9 of 20 digits (45%). The difference in rates of all intra-sheath injection was significant (P = .01). The mid-axial technique also produced the fewest intra-tendinous injections 0 of 20, although this result did not reach statistical significance (P = .15). Compared to other common non-image guided flexor tendon sheath injection techniques, the mid-axial injection technique was found to be the most accurate in producing all intra-sheath injection and least likely to result in intra-tendinous injection.

Biomechanical analysis of stand-alone lumbar interbody cages versus 360° constructs: an in vitro and finite element investigation.

Low fusion rates and cage subsidence are limitations of lumbar fixation with stand-alone interbody cages. Various approaches to interbody cage placement exist, yet the need for supplemental posterior fixation is not clear from clinical studies. Therefore, as prospective clinical studies are lacking, a comparison of segmental kinematics, cage properties, and load sharing on vertebral endplates is needed. This laboratory investigation evaluates the mechanical stability and biomechanical properties of various interbody fixation techniques by performing cadaveric and finite element (FE) modeling studies. An in vitro experiment using 7 fresh-frozen human cadavers was designed to test intact spines with 1) stand-alone lateral interbody cage constructs (lateral interbody fusion, LIF) and 2) LIF supplemented with posterior pedicle screw-rod fixation (360° constructs). FE and kinematic data were used to validate a ligamentous FE model of the lumbopelvic spine. The validated model was then used to evaluate the stability of stand-alone LIF, transforaminal lumbar interbody fusion (TLIF), and anterior lumbar interbody fusion (ALIF) cages with and without supplemental posterior fixation at the L4-5 level. The FE models of intact and instrumented cases were subjected to a 400-N compressive preload followed by an 8-Nm bending moment to simulate physiological flexion, extension, bending, and axial rotation. Segmental kinematics and load sharing at the inferior endplate were compared. The FE kinematic predictions were consistent with cadaveric data. The range of motion (ROM) in LIF was significantly lower than intact spines for both stand-alone and 360° constructs. The calculated reduction in motion with respect to intact spines for stand-alone constructs ranged from 43% to 66% for TLIF, 67%-82% for LIF, and 69%-86% for ALIF in flexion, extension, lateral bending, and axial rotation. In flexion and extension, the maximum reduction in motion was 70% for ALIF versus 81% in LIF for stand-alone cases. When supplemented with posterior fixation, the corresponding reduction in ROM was 76%-87% for TLIF, 86%-91% for LIF, and 90%-92% for ALIF. The addition of posterior instrumentation resulted in a significant reduction in peak stress at the superior endplate of the inferior segment in all scenarios. Stand-alone ALIF and LIF cages are most effective in providing stability in lateral bending and axial rotation and less so in flexion and extension. Supplemental posterior instrumentation improves stability for all interbody techniques. Comparative clinical data are needed to further define the indications for stand-alone cages in lumbar fusion surgery.

A Non-invasive Method to Assess Tensor Tympani Muscle Contraction in Response to Tactile Stimulation.

The function of the tensor tympani muscle and its effects, as well as a universal testing procedure, is not yet known. The purpose of this study is to investigate the effect of tactile stimulation on the tensor tympani muscle activity in an attempt to evaluate the functional status of the muscle. In this study, 20 healthy adults aged between 18 and 30 years were included. All participants had their history taken, as well as the evaluation of otoscopy, audiometry, and tympanometry. A modified reflex decay paradigm was used to evaluate the tensor tympani muscle activity, in both humans and a fresh-frozen cadaver. The tactile stimulation was applied by thumb tappings on different forehead areas. Reflex decay responses were in the form of the absence of a response or either a positive or negative waveform. Tactile stimulation had no impact on reflex decay recordings obtained from the cadaver. There was no significant difference between the waveforms obtained from both ears, at different stimulation frequencies, tactile stimulation areas, or the 3 successive stimuli for 1 individual in 1 ear (P > .05). Changes observed in the reflex decay test upon tactile stimulation seem to be due to tensor tympani muscle activity as supported by the previous findings in the literature. The application of a tactile stimulus on the forehead is a non-invasive test method to assess tensor tympani muscle contraction. Understanding the function of the tensor tympani muscle using a non-invasive method will be helpful during the decision-making process in the practice of otology.

The Effect of Flexor Carpi Ulnaris Pulley Design on Tendon Gliding Resistance After Flexor Digitorum Superficialis Tendon Transfer for Opposition Transfer

The flexor digitorum superficialis (FDS) tendon transfer can be used to restore opposition of the thumb. Several pulley designs have been proposed for this transfer. Gliding resistance is considered to be an important factor influencing the efficiency of the pulley design. Our purpose was to compare the gliding resistance among 4 commonly used pulleys for the FDS oppositional transfer. Ten fresh-frozen cadaver specimens were studied. The ring FDS was used as the donor tendon. An oppositional transfer was created using 4 pulley configurations: FDS passed around the flexor carpi ulnaris (a-FCU), FDS passed through a 2.5-cm circumference distally based FCU loop (2.5-FCU), FDS passed through a 3.5-cm circumference distally based FCU loop (3.5-FCU), and FDS passed through a longitudinal split in the FCU tendon (s-FCU). The gliding resistance was measured with the thumb in radial abduction and maximum opposition. In abduction, the average FDS gliding resistance of a-FCU, 2.5-FCU, 3.5-FCU, and s-FCU was 0.66 N (SD, 0.14 N), 0.70 N (SD, 0.14 N), 0.68 N (SD, 0.16 N), and 0.79 N (SD, 0.15 N), respectively. The peak gliding resistance of a-FCU, 2.5-FCU, 3.5-FCU, and s-FCU was 0.75 N (SD, 0.16 N), 0.74 N (SD, 0.15 N), 0.74 N (SD, 0.15 N), and 0.86 N (SD, 0.15 N), respectively. The average gliding resistance of the s-FCU was found to be significantly higher than that of the a-FCU and 3.5-FCU pulleys. In opposition, there were no differences in average or peak gliding resistance among the different pulley designs. In this invitro cadaveric study, the FDS split pulley produced higher gliding resistance. Consideration of the pulley configuration may improve the overall thumb function by decreasing forces needed to overcome gliding resistance.

Training on skin flap elevation in hand surgery using cadavers embalmed by the saturated salt solution method: effectiveness and usefulness.

Thiel embalmed and fresh-frozen cadavers have been mainly used for hand surgery training. We held a training seminar on skin flap elevation using cadavers embalmed by the saturated salt solution method. This study aimed to evaluate the usefulness of such training and to validate the suitability of saturated salt solution-embalmed cadavers for hand surgery training. Participants were trained in elevation procedures for the oblique triangular, reverse digital artery, reverse radial forearm, and reverse dorsal metacarpal artery flaps. Forty-eight surgeons participated in three seminars (one held in 2017, 2018, and 2019 each). A self-assessment of the participants' confidence levels for their surgical skills was performed before and immediately after the seminar, and the suitability of saturated salt solution-embalmed cadavers was determined in terms of visual perception, tactility, comparison with real-world surgical settings, and usefulness. The confidence level for all skills increased immediately after the seminar. The surgeons reported that the visual perception and tactility of the saturated salt solution-embalmed cadavers were comparable to those of a living body, and the cadavers were rated higher with respect to their usefulness. Hand surgery seminars using cadavers embalmed by the saturated salt solution method are considered useful for training in skin flap techniques.

The risk of Creutzfeldt–Jakob disease infection in cadaveric surgical training

The usefulness of cadaver surgical training in the clinical field is already well known. In Japan, the number of universities introducing cadaver surgical training is increasing. In addition to formalin fixation, various fixation methods are used, such as the Thiel method, saturated salt solution method, N-vinyl-2-pyrrolidone method, and fresh-frozen cadavers. Although protection against infections during fixation and cadaver surgical training has been implemented in most universities, it is currently inadequate. Furthermore, the possibility of undiagnosed infectious diseases in donors cannot be excluded. Prion diseases, such as Creutzfeldt-Jakob disease, are relatively rare, but they are fatal, with no effective treatment. The abnormal prion protein that causes prion diseases is resistant to formaldehyde and cannot be inactivated by all methods of cadaver fixation presently in use. Recently developed real-time quaking-induced conversion has been reported to be a useful screening method for prion infection. In addition, this article aims to raise awareness of prion diseases in cadaver surgical training by reviewing the current understanding of prion diseases in cadavers and their screening methods.

Supination Adduction Vertical Medial Malleolar Fracture Fixation with Buttress Plating vs a Novel Screw-Only Construct: A Cadaveric Biomechanical Study.

Supination adduction ankle fractures are unique among rotational ankle fractures as plate constructs are more commonly used than independent screws for medial malleolar fixation. The purpose of this study was to compare fracture displacement between plate fixation to a novel screw-only construct using a cadaveric biomechanical early-weightbearing model for the treatment of vertical medial malleolus fractures. Six nonosteoporotic fresh-frozen cadaver shanks and feet in matched pairs underwent a vertical osteotomy of the medial malleolus to simulate the supination adduction type injury. Osteoporosis was measured using DEXA scans. One specimen from each pair was fixed with a one-third tubular buttress plate and the other with screw-only fixation. The specimens were then axially loaded for 100 000 cycles to simulate protected weightbearing, and subsequently loaded to failure in supination. Stiffness, fracture displacement, and load to failure were recorded. Statistical significance was set at P <.05. There were no measurable differences in displacement between the 2 constructs during axial cyclic loading after 100 000 cycles (plate, 0.74 ± 0.09 mm; screws, 0.79 ± 0.18 mm; P = .225). During supination and axial load to failure, the plate outperformed the screw construct. For load to failure (2 mm displacement) at the fracture site, the plate group failed at 716 ± 240 N, whereas the screw group failed at 567 ± 237 N (P = .015). During load to catastrophic failure, the plate group outperformed the screw group (plate, 6011 ± 1646 N; screws, 4578 ± 1837 N; P = .002). For vertical medial malleolar fractures, the screw-only construct demonstrated no statistical difference when compared to buttress plating for cyclical axial loading, simulating early weightbearing in a boot. However, buttress plating is 21% to 24% stronger than the screw-only fixation construct in overall strength and prevention of catastrophic failure when loading in a supinated position. The screw-only construct is biomechanically similar to a buttress plate when simulating early protected weightbearing. This suggests that early weightbearing as tolerated in a controlled ankle motion boot beginning 2 weeks postoperatively is mechanically safe for this fracture pattern and does not result in unacceptable amounts of fracture displacement. This construct may be useful as a less invasive treatment modality for the treatment of vertical medial malleolus fractures in select patients.

Re-creating reality: validation of fresh frozen full cadaver airway training with videolaryngoscopy and bougie FIRST strategy

BackgroundTracheal intubation is the gold standard in emergency airway management. One way of measuring intubation quality is first pass success rate (FPSR). Mastery of tracheal intubation and maintenance of the skill is challenging for non-anesthesiologists. A combination of individual measures can increase FPSR. Videolaryngoscopy is an important tool augmenting laryngeal visualization. Bougie-first strategy can further improve FPSR in difficult airways. Standardized positioning maneuvers and manipulation of the soft tissues can enhance laryngeal visualization. Fresh frozen cadavers (FFC) are superior models compared to commercially manufactured manikins. By purposefully manipulating FFCs, it is possible to mimic the pre-hospital intubation conditions of helicopter emergency medical service (HEMS).MethodsTwenty-four trauma surgeons (12 per Group, NOVICES: no pre-hospital experience, HEMS: HEMS physicians) completed an airway training course using FFCs. The FFCs were modified to match airway characteristics of 60 prospectively documented intubations by HEMS physicians prior to the study (BASELINE). In four scenarios the local HEMS airway standard (1: unaided direct laryngoscopy (DL), OLD) was compared to two scenarios with modifications of the intubation technique (2: augmented DL (bougie and patient positioning), 3: augmented videolaryngoscopy (aVL)) and a control scenario (4: VL and bougie, positioning by participant, CONTROL). FPSR, POGO score, Cormack and Lehane grade and duration of intubation were recorded. No participant had anesthesiological qualifications or experience in VL.ResultsThe comparison between CONTROL and BASELINE revealed a significant increase of FPSR and achieved C&L grade for HEMS group (FPSR 100%, absolute difference 23%, p ≤ .001). The use of videolaryngoscopy, bougie, and the application of positioning techniques required significantly more time in the CONTROL scenario (HEMS group: mean 34.0 s (IQR 28.3–47.5), absolute difference to BASELINE: 13.0 s, p = .045). The groups differed significantly in the median number of real-life intubations performed in any setting (NOVICES n = 5 (IQR 0–18.75), HEMS n = 68 (IQR 37.25–99.75)). In the control scenario no significant differences were found between both groups. The airway characteristics of the FFC showed no significant differences compared to BASELINE.ConclusionAirway characteristics of a pre-hospital patient reference group cared for by HEMS were successfully reproduced in a fresh frozen cadaver model. In this setting, a combination of evidence based airway management techniques results in high FPSR and POGO rates of non-anesthesiological trained users. Comparable results (FPSR, POGO, duration of intubation) were achieved regardless of previous provider experience. The BOAH concept can therefore be used in the early stages of airway training and for skill maintenance.

Morphology of the trigeminal ganglion: anatomical structures related to trigeminal radiofrequency rhizotomy.

Trigeminal neuralgia is the most common example of craniofacial neuralgia. Its etiology is unknown and is characterized by severe episodes of paroxysmal pain. The trigeminal ganglion and its adjacent anatomical structures have a complex anatomy. The foramen ovale is of great importance during surgical procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia. We aimed to identify the anatomical structures associated with the trigeminal ganglion and radiofrequency rhizotomy on cadavers and investigate their relationship with the electrodes used during rhizotomy to determine the contribution of the electrode diameter and length to the effectiveness of the lesion formation on the ganglion. Five fresh-frozen cadaver heads injected with red silicone/latex were used. A percutaneous puncture was made by inserting of a cannula through the foramen ovale to create a pathway for electrodes. The relationships between the electrodes, Meckel's cave, trigeminal ganglion, and neurovascular structures were observed and morphometric measurements were obtained using a digital caliper. Trigeminal ganglion, therefore the electrode in its final position, shows proximity with important anatomical structures. The electrode was inserted posteriorly into the foramen ovale in all of the specimens and was located on the retrogasserian fibers. This study revealed that the electrodes targeting the ganglion and passing through the foramen ovale may cause a radiofrequency lesion due to the contact effect of the dura itself pressing on the electrode. Pushing the cannula beyond the petroclival angle may result in puncturing of the dura propria and moving further away from the target area. The success of radiofrequency rhizotomy is directly related to the area affected by the lesion. Understanding the mechanism of action underlying this procedure will ensure the effectiveness, success, and sustainability of the treatment.

Effect of Proximal Row Carpectomy and Wrist Arthrodesis on the Resting Length of Extrinsic Digit Flexor Tendons: A Cadaveric Study

Background Spastic joint contractures remain a complex and challenging condition. For patients with upper extremity spastic dysfunction, improving the muscle balance is essential to maximize their hand function. Multiple procedures, including proximal row carpectomy (PRC) and wrist arthrodesis (WA), are considered among the different surgical alternatives. However, the biomechanical consequences of these two procedures have not been well described in current literature. Hence, the objective of our study is to assess the change in the extrinsic digit flexor tendon resting length after proximal row carpectomy and wrist arthrodesis.Methods Six fresh-frozen cadaver upper extremities (four females and two males) with no obvious deformity underwent dissection, PRC, and WA. All the flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), and flexor pollicis longus (FPL) tendons were marked proximally 1-cm distal to their respective myotendinous junction and cut distally at the marked point. The overlapping segment of each distal flexor tendon from its proximal mark was considered the amount of flexor tendon resting length change after PRC and WA. A descriptive evaluation was performed to assess the increment in tendon resting length. Additionally, a regression analysis was performed to evaluate the relation between the tendon resting length and the proximal carpal row height.Results Following PRC and WA, the mean digit flexor tendon resting length increment achieved across all tendons was 1.88 cm (standard deviation [SD] = 0.45; range: 1.00–3.00 cm). A weak direct relationship (R = 0.0334) between the increment in tendon resting length and proximal carpal row height was initially suggested, although no statistical significance was demonstrated (p = 0.811).Conclusion This study provides an anatomic description of the increased extrinsic digit flexor tendon resting length after PRC and WA in cadaveric specimens. Findings provide a useful framework to estimate the amount of extrinsic digit flexor resting length increment achieved after wrist fusion and the proximal carpal row removal.

Does endoscopic balloon dilatation improve intranasal drug delivery to the olfactory cleft? A pre-clinical cadaver feasibility study.

Although systemic steroids have been shown to improve olfactory function, topical steroids have not demonstrated the same efficacy. This could a result of limited drug delivery to the narrow, superiorly placed olfactory cleft. This study aimed to examine the penetration of intranasal drugs to the olfactory cleft following endonasal balloon dilatation. Balloon dilatation was performed in 12 thawed, fresh-frozen cadaver specimens. In the Mygind position, nasal drops mixed with blue food dye were administered into the nostril before and after the dilatation procedure. Endoscopic videos were recorded to assess dye staining of the olfactory cleft and osteo-meatal complex using a 4-point Likert scale. Prior to balloon dilatation, the mean penetration of nasal drops into the olfactory cleft was 1.34, which improved significantly (p < 0.05) to 2.66 following the procedure. There was no change in dye penetration into the osteo-meatal complex after balloon dilatation. The results of this exploratory study suggest that balloon dilatation may improve the delivery of nasal drops to the olfactory cleft area. The clinical applicability and impact on olfactory function will require further assessment.

Human cadaver model as a training tool for enzymatic burn debridement (Nexobrid®): A feasibility study

ObjectivesTo determine the feasibility of using human cadavers to demonstrate enzymatic burn debridement, as a training aid for clinical staff. Material and methodsA single, fresh-frozen human cadaver was used. Prior consent had been given. Burns were created by flame and scalding. Unburned control sites were also assessed. Nexobrid® enzymatic burn debridement paste was applied to all sites, in adherence to the local clinical protocol for treating burned patients. After removal of Nexobrid®, wounds were assessed to determine if the cadaveric tissue appeared similar to what would be expected in living burned patients and whether the technique could be viable for training of burn care staff. ResultsNexobrid® had a very similar effect upon burned cadaveric skin to what would have been expected in living burned skin. Burns of partial thickness burn depth and full thickness burn depth were debrided and could be clearly identified. ConclusionsFresh-frozen human cadaveric tissue is a valid means of provision of training in the technique of enzymatic burn debridement. This finding was unexpected and shows that our understanding of the mechanism of action of Nexobrid® is incomplete.

Endoscopic Gluteus Medius Repair Replicates Open, Knotless Repair With Similar Cyclic Loading Properties: A Cadaveric Study

PurposeTo compare the repair strength, gap formation, and mode of failure between endoscopic and open double-row gluteus medius repairs in a cadaveric model.MethodsSix pairs of fresh-frozen human cadavers were used in this study. Gluteus medius tears were created in an open fashion and then repaired with either open or endoscopic techniques. Specimens were manually preloaded to 5 N, then cycled between 20-50 N for 150 cycles s. Then, a ramp to/s. Specimens were then returned to 10 N and ramped to failure at 1 mm/s. Gap formation and strengths of the construct were compared for the 2 techniques.ResultsBiomechanical testing resulted in no significant differences in ultimate load (P = .86) or gap formation (P > .10) between groups. Ninety-two percent of specimens failed near the muscle origin on the ilium.ConclusionsThis study shows that both open and endoscopic gluteus medius repairs are stronger than the muscle–bone interface in a cadaveric model and loaded biomechanically in tension between the ilium origin and femoral insertion. Further, endoscopic technique is able to replicate open, knotless gluteus medius repair technique in terms of gap formation in physiologic (i.e., subfailure) cyclic loading.Clinical RelevanceGluteus medius tendinopathy is an increasingly common recognized etiology of lateral hip pain. When tears occur, debate exists over whether open or endoscopic repair procedures are optimal. Double-row endoscopic gluteus medius repair with knotless suture anchors may be an alternative to open repair.