Equine Cadaver Research Articles

The combination of mitogenic stimulation and DNA damage induces chondrocyte senescence

Cellular senescence is a phenotypic state characterized by stable cell-cycle arrest, enhanced lysosomal activity, and the secretion of inflammatory molecules and matrix degrading enzymes. Senescence has been implicated in osteoarthritis (OA) pathophysiology; however, the mechanisms that drive senescence induction in cartilage and other joint tissues are unknown. While numerous physiological signals are capable of initiating senescence, one emerging theme is that damaged cells convert to senescence in response to sustained mitogenic stimulation. The goal of this study was to develop an in vitro articular cartilage explant model to investigate the mechanisms of senescence induction. This study utilized healthy cartilage derived from cadaveric equine stifles and human ankles. Explants were irradiated to initiate DNA damage, and mitogenic stimulation was provided through serum-containing medium and treatment with transforming growth factor β1 and basic fibroblastic growth factor. Readouts of senescence were a quantitative flow cytometry assay to detect senescence-associated β galactosidase activity (SA-β-gal), immunofluorescence for p16 and γH2AX, and qPCR for the expression of inflammatory genes. Human cartilage explants required both irradiation and mitogenic stimulation to induce senescence as compared to baseline control conditions (7.16% vs 2.34% SA-β-gal high, p=0.0007). These conditions also resulted in chondrocyte clusters within explants, a persistent DNA damage response, increased p16, and gene expression changes. Treatment of cartilage explants with mitogenic stimuli in the context of cellular damage reliably induces high levels of SA-β-gal activity and other senescence markers, which provides a physiologically relevant model system to investigate the mechanisms of senescence induction.

Radiographic assessment of carpal conformation in the horse: Technique development and validation of the consistency of measurements.

Carpal conformation is often considered as a contributory factor to performance and lameness in the horse; however, few attempts have been made to objectively measure radiographic variations of carpal conformation in horses due to insufficient measurable carpal parameters. This pilot study used carpal radiographic images acquired from 10 cadaveric equine forelimbs transected at the antebrachial midshaft from 7 adult horses (7.2±2.6years), positioned at 'zero lateromedial' (ZLM) and 'zero dorsopalmar' (ZDP) views, to investigate the anatomy of the equine carpus and develop parameters that could be objectively used to assess carpal conformation in horses. Dorsal carpal angle (DCA: 176.61±0.66º), distal radial slope carpal angle (DRSCA: 145.59±2.19º), intermediate carpal bone proximal tuberosity-radial angle (CiPxTRA: 115.69±3.15º) and third carpal bone palmar facet angle (C3PalFCA: 84.43±1.13º) were all developed from the ZLM view while medial carpal angle (MCA: 183.34±1.02º), disto-dorsal slope angle of the third carpal bone (C3DDSA: 8.27±0.92º) and width ratio of distal radius to proximal metacarpus (WDR:WPM=1.13±0.03) were 3 of the 10 parameters developed from the ZDP view. Easy to identify and measurable parameters will help to provide quantitative assessment of carpal conformation in the horse with potential of eliminating subjective observational variation errors between clinicians. These newly developed parameters will be useful in further studies to measure variations in the conformation of the equine carpus in live horses and comparison between subjective visual assessment and objective radiographic evaluation methods.

Morphometric analysis of the intercarpal ligaments of the equine proximal carpal bones during simulated flexion and extension of cadaver limbs

Despite many reported cases of carpal lameness associated with intercarpal ligament injuries in horses, the morphometry, movement pattern and general intrinsic biomechanics of the carpus are largely unknown. Using osteoligamentous preparation of the carpus prepared from 14 equine cadaver forelimbs (aged 9.62±4.25years), locomotory simulations of flexion and extension movements of the carpal joint were carried out to observed carpal biomechanics and, thereafter, the limbs were further dissected to obtain morphometric measurements of the medial and lateral collateral ligaments (MLC and LCL); medial and lateral palmar intercarpal ligaments (MPICL and LPICL); intercarpal ligaments between radial (Cr) and intermediate (Ci) carpal bones (Cr-Ci ICL); and intercarpal ligaments between Ci and ulnar (Cu) carpal bones (Ci-Cu ICL). The Cr, Ci, Cu and Ca are held together by a series of intercarpal ligaments and move in unison lateropalmarly during flexion, and mediodorsally during extension with a distinguishable proximo-distal sliding movement (gliding) of Cr and Ci against each other during movement. The mean length of MCL (108.82±9.64 mm) was significantly longer (p=0.042) than LCL (104.43±7.65 mm). The Cr-Ci ICL has a dorsopalmar depth of 37.58±4.14mm and a midpoint width of 12.05±3.09mm and its fibres ran diagonally from the medial side of the Ci in a proximo-palmar disto-dorsal direction (i.e. palmarodistally) to the lateral side of the Cr. The specialized movement of the Cr-Ci ICL, which appeared to be further facilitated by a longer MCL suggest a biomechanical function by which carpal damage may be minimized in the equine carpus.

Anatomy and Ultrasound-Guided Injection of the Medial Branch of the Dorsal Ramus of the Cervical Spinal Nerves in the Horse: A Cadaveric Study.

The aim of this study was to describe the anatomy of the nerves supplying the cervical articular process joint and to identify relevant anatomical landmarks that could aid in the ultrasound-guided location and injection of these nerves for diagnostic and therapeutic purposes. Twelve cadaveric equine necks were used. Five necks were dissected to study the anatomy of the medial branch of the dorsal ramus of the cervical spinal nerves 3 to 7. Relevant anatomical findings detected during dissections were combined with ultrasonographic images obtained in one other neck. Six additional necks were used to assess the accuracy of ultrasound-guided injections of the medial branch with blue dye. Each examined cervical articular process joint, except for C2 to C3, presented a dual nerve supply. The articular process joints were found to be in close anatomical relationship with the medial branch of the dorsal ramus of the cervical spinal nerve exiting from the intervertebral foramen at the same level, and with the medial branch of the dorsal ramus of the cervical spinal nerve exiting from the intervertebral foramen one level cranial to the articular process joint of interest. A total of 55 nerves were injected under ultrasonographic guidance, 51 of which were successfully stained. The current study provided new detailed information regarding the innervation of the cervical articular process joint. The medial branches of the dorsal rami of the cervical spinal nerves were injected with an accuracy that would be of clinical value. Our study offers the foundations to develop new diagnostic and therapeutic techniques for pain management in cervical articular process joint arthropathy in horses.

Ex vivo modeling of the airflow dynamics and two-and three-dimensional biomechanical effects of suture placements for prosthetic laryngoplasty in horses.

To identify the degree of left arytenoid cartilage (LAC) abduction that allows laryngeal airflow similar to that in galloping horses, assess 2-D and 3-D biomechanical effects of prosthetic laryngoplasty on LAC movement and airflow, and determine the influence of suture position through the muscular process of the arytenoid cartilage (MPA) on these variables. 7 equine cadaver larynges. With the right arytenoid cartilage maximally abducted and inspiratory airflow simulated by vacuum, laryngeal airflow and translaryngeal pressure and impedance were measured at 12 incremental LAC abduction forces (0% to 100% [maximum abduction]) applied through laryngoplasty sutures passed caudocranially or mediolaterally through the left MPA. Cross-sectional area of the rima glottis and left-to-right angle quotient were determined from photographs at each abduction force; CT images were obtained at alternate forces. Arytenoid and cricoid cartilage markers allowed calculation of LAC roll, pitch, and yaw through use of Euler angles on 3-D reconstructed CT images. Translaryngeal pressure and impedance decreased, and airflow increased rapidly at low abduction forces, then slowed until a plateau was reached at approximately 50% of maximum abduction force. The greatest LAC motion was rocking (pitch). Suture position through the left MPA did not significantly affect airflow data. Approximately 50% of maximum abduction force, corresponding to a left arytenoid angle of approximately 30° and left-to-right angle quotient of 0.79 to 0.84, allowed airflow of approximately 61 ± 6.5 L/s. Ex vivo modeling results suggested little benefit to LAC abduction forces > 50%, which allowed airflow similar to that reported elsewhere for galloping horses.

Arthroscopic approach and intra-articular anatomy of the equine discomandibular joint compartment of the temporomandibular joint.

To develop an arthroscopic approach to the discomandibular joint (DMJ), the ventral compartment of the temporomandibular joint (TMJ) of the horse. Experimental study. Nine cadaveric equine heads and two live horses. A 2.5-mm 30° arthroscope was used to explore the DMJ after joint distension. The first portal was created caudally, allowing placement of a rostral portal under visual guidance. Nasotracheal intubation of the live horses allowed mandibular manipulation, which is required for complete visualization of the joint. A novel injection technique allowed consistent arthrocentesis of the DMJ. The joint could be completely explored by using both portals and manipulation of the mandible. Variations in the medial joint capsule were observed between horses along with a cyst of the mandibular condyle in one horse. The only complication consisted of damage to the parotid salivary gland, which occurred in three cadaver heads. No communication was found between the joint compartments of the TMJ. Correct portal placement and intraoperative manipulation of the mandible were critical and allowed complete exploration and debridement of the DMJ. Determining the independence of the TMJ joint compartments has clinical ramifications for the diagnosis and treatment of clinical disorders. Most TMJ pathology, notwithstanding sepsis, is identified within the DMJ. Arthroscopic exploration of the DMJ is possible and may help manage these conditions.

Retroperitoneoscopy in the horse: Anatomical study of the retroperitoneal perirenal space and description of a surgical approach.

Surgical approaches to the kidneys and perirenal structures are uncommonly performed in horses and several complications have been described with the current procedures. To describe the anatomy of the retroperitoneal perirenal space and investigate a retroperitoneal minimally invasive approach to access the kidney and perirenal structures in horses. Descriptive, cadaveric study. Anatomical description of the retroperitoneal space was performed on three equine cadavers and the surgical approach was developed based on these dissections. Ten cadaveric horses underwent a retroperitoneoscopy. Five horses were placed in a right lateral recumbency position to explore the left retroperitoneal space and five horses were placed in a standing position to explore both left and right sides. Anatomical landmarks, working space and access to the renal hilus and perirenal structures were evaluated. Dissections revealed that kidneys are surrounded by a renal fascia which delimits two spaces: a perirenal space between the kidney and the renal fascia, and a pararenal space between the renal fascia and psoas muscles or peritoneum. The retroperitoneoscopic portal was placed at the level of the dorsal aspect of the tuber coxae, 3cm caudal to the last rib for the left side and 2cm caudal to the last rib for the right side. Retroperitoneal access and working space were successfully established in all horses. The standing position allowed an easier dissection than lateral recumbency. Division of the perirenal fat allowed access to the kidney and adrenal glands as well as individualisation of renal vessels and ureter in the renal hilus. Study of cadavers precluded appreciation of haemorrhage or use the pulsating vessels as landmarks. This study provides a description of the retroperitoneal perirenal space and describes a new surgical approach to access kidneys and perirenal structures in horses.

A pilot study of optical neuronavigation-guided brain biopsy in the horse using anatomic landmarks and fiducial arrays for patient registration.

BackgroundOptical neuronavigation‐guided intracranial surgery has become increasingly common in veterinary medicine, but its use has not yet been described in horses.ObjectivesTo determine the feasibility of optical neuronavigation‐guided intracranial biopsy procedures in the horse, compare the use of the standard fiducial array and anatomic landmarks for patient registration, and evaluate surgeon experience.AnimalsSix equine cadaver heads.MethodsComputed tomography images of each specimen were acquired, with the fiducial array rigidly secured to the frontal bone. Six targets were selected in each specimen. Patient registration was performed separately for 3 targets using the fiducial array, and for 3 targets using anatomic landmarks. In lieu of biopsy, 1 mm diameter wire seeds were placed at each target. Postoperative images were coregistered with the planning scan to calculate Euclidian distance from the tip of the seed to the target.ResultsNo statistical difference between registration techniques was identified. The impact of surgeon experience was examined for each technique using a Mann‐Whitney U test. The experienced surgeon was significantly closer to the intended target (median = 2.52 mm) than were the novice surgeons (median = 6.55 mm) using the fiducial array (P = .001). Although not statistically significant (P = .31), for the experienced surgeon the median distance to target was similar when registering with the fiducial array (2.47 mm) and anatomic landmarks (2.58 mm).Conclusions and Clinical ImportanceRegistration using both fiducial arrays and anatomic landmarks for brain biopsy using optical neuronavigation in horses is feasible.

Is the T-ligament a ligament? A histological study in equine cadaver forelimbs

Foot pain is a frequent cause of lameness in horses and can involve multiple structures within the hoof. The T-ligament (an anatomical structure connecting the synovium of the distal interphalangeal joint, the digital flexor tendon sheath and the navicular bursa) is poorly described.Five pairs of equine cadaver distal forelimbs were collected from a slaughterhouse. Sagittal sections (medial, middle and lateral) were obtained and processed with Haematoxylin Eosin Safran, Unna's Orcein, and Picrosirius red stains.Histological assessment revealed that the T-ligament was covered by the surrounding synovia of the distal interphalangeal joint, the digital flexor tendon sheath and the navicular bursa. Its collagen content was lower (30.01%±10.15) than that of the collateral sesamoidean ligament (89.48%±5.8; P = .0008) and the middle phalanx (85.72%±3.67; P = .0008). Under polarized light microscopy, it showed a slight heterogeneous pattern of birefringence, with angle-related changes. Elastic fibres were more numerous (21.76%±8.72) than in the collateral sesamoidean ligament (0.28%±0.45), or deep digital flexor tendon (0.04%±0.02); and were more densely packed. Mean cell count was higher for the T-ligament than for other tissues (P = .0007). Blood vessels were identified in the T-ligament and were penetrating the deep digital flexor tendon (8/10 limbs, 5/5 horses).In conclusion, the T-ligament looked like a vinculum for the deep digital flexor tendon, with a central elastic core, surrounding loose connective tissue and blood vessels. It is not a ligament. Its clinical relevance still needs to be determined.

An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

The aim of this study is to determine what loads are likely to be applied to the head in the event of a horse falling onto it and to determine by how much a typical equestrian helmet reduces these loads. An instrumented headform was designed and built to measure applied dynamic loads from a falling horse. Two differently weighted equine cadavers were then dropped repeatedly from a height of 1 m (theoretical impact velocity of 4.43 m/s) onto both the un-helmeted and helmeted instrumented headforms to collect primary force–time history data. The highest mean peak loads applied to the headform by the lighter horse were measured at the bony sacral impact location (15.57 kN ± 1.11 SD). The lowest mean peak loads were measured at the relatively fleshier right hind quarter (7.91 kN ± 1.84 SD). For the heavier horse, highest mean peak loads applied to the headform were measured at the same bony sacral impact location (16.02 kN ± 0.83 SD), whilst lowest mean peak loads were measured at the more compliant left hind quarter (10.47 kN ± 1.08 SD). When compared with the un-helmeted mean values, a reduction of 29.7% was recorded for the sacral impact location and a reduction of 43.3% for the lumbosacral junction location for helmeted tests. Notably, all measured loads were within or exceeded the range of published data for the fracture of the adult lateral skull bone. Current helmet certification tests are not biofidelic and inadequately represent the loading conditions of real-world “lateral crush” accidents sustained in equestrian sports. This work presents the first ever evidence basis upon which any future changes to a certification standards test method might be established, thereby ensuring that such a test would be both useful, biofidelic, and could ensure the desired safety outcome.

Ultrasonography-Guided Perineural Injection of the Ramus ventralis of the 7 and 8th Cervical Nerves in Horses: A Cadaveric Descriptive Pilot Study.

Objective: To describe the feasibility and dye diffusion of selective perineural injection of the 7 and 8th cervical nerve (C7 and C8) ramus ventralis under ultrasonographic guidance in horses.Study design: Prospective experimental pilot cadaver study.Animals: Four equine cadavers of similar body weight (420–480 kg) and neck conformation.Methods: Five C7 and five C8 rami were perineurally injected with a dye solution. Anatomic dissections including vertebral canal opening were conducted to confirm nerve dye staining and describe the extent of color diffusion.Results: The ramus ventralis of the spinal cervical nerves was visualized in all cadavers. All the injections were successful in staining a portion of the nerve trunk. Eight rami had a uniform transversal staining of the nerve trunk that longitudinally covered a distance >2 cm. One C7 and one C8 nerve trunk showed incomplete transversal staining with a more concentrated color on its half cranial aspect and a longitudinal coverage of <2 cm. Five injections resulted in dye extending proximally and medially into the epidural space. Volume had no appreciable effect on the extent of nerve staining. A greater proportion of epidural diffusion was found with injections done within less than one cm distally to the articular processes. All injections were considered to be selective for the targeted nerve.Conclusion and clinical relevance: Ultrasonography-guided perineural injection of C7 and C8 ramus ventralis is a feasible technique that may have multiple applications in multimodal analgesia in horses. Further clinical study will be necessary to determine the appropriate drug, dosage, and volume to inject and to confirm its usefulness.

Insertional characteristics of three types of transfixation pin taps in third metacarpal bones from equine cadavers.

To compare heat generation and mechanical bone damage achieved with 2 tapered and 1 cylindrical transfixation pin taps in third metacarpal bones from equine cadavers. 18 pairs (36 specimens) of third metacarpal bones from euthanized horses with no known metacarpal disease. In each bone, an investigator drilled 3 holes for placement of a 6.3-mm cylindrical transfixation pin, a 6.3-mm tapered pin using a prototype tapered tap, and a 6.3-mm tapered pin using a revised tapered tap. One bone of each pair was tapped by hand and the other with an electric drill. Temperatures of the drill bits, reamers, and taps were measured and used to compare heat generation among tap groups and tapping methods (hand vs power tapping). Macrodamage (all bone pairs) and microdamage (6 bone pairs) were assessed. The revised tapered tap resulted in less heat generation and less total thread microdamage, compared with the prototype tapered and cylindrical taps. Power tapping created less bone damage but higher temperatures than did hand tapping for all bone groups. The revised tap design for tapered pin insertion was superior to the prototype tap design and yielded similar or less bone damage than achieved with cylindrical pin insertion in equine third metacarpal bone specimens. We recommend careful hand tapping for tapered pin insertion rather than power tapping, which generated greater heat. The revised tapered tap could be expected to perform better than a cylindrical pin tap in terms of thermal and mechanical microdamage and should be used for insertion of tapered transfixation pins.

Nanofracturing: a new technique for bone marrow stimulation in equine cartilage repair

Microfracture is the current standard in treatment of focal full-thickness cartilage lesions in horses, but clinical outcome may vary. Nanofraclure is a novel technique that uses a commercially developed device to yield smaller diomeler perforations with deeper penetration into the subchondral bone. Experimentally, in rabbits and sheep, nanofrocture has been shown to result in superior repair compared to microfracture. The objective was to study the feasibility and preliminary outcome of nanofrocture using o commercial device for treotment of cartilage defects in horses. Nonofracture was tested ex vivo in n = 2 cadaveric equine stifle joints and in vivo in n = 8 horses with experimental portiol thickness cartilage defects in the medial femoral trochlear ridge. These were treoted with an experimental biomaterial or nanofrocture, and repair tissue was studied mocroscopically (ICRS-I score) and microscopically (histological ICRS-II score ond micro-CT) ofter 7 months. Both in cadaveric equine stifle joints and in vivo, the nanofrocture device could reodily be applied and allowed easy penetration of the subchondral bone. Repoir tissue ofter 7 months was groded 'near-normal' macroscopically, while histologically, the obundant repair tissue proved mainly fibrocartilaginous in nature. Micro-CT revealed near-full restoration of mid-lesion cortilage layer thickness but oltered subchondral bone microarchitecture. The in vivo study did not include a control group treated with conventional microfracture for comparison. To our knowledge, this is the first report on bone marrow stimulation using nanofrocture as a potential method to enhance chondral defect repair in horses. In the in vivo study, no clinical odverse effects were observed, and promising good defect filling with fibrocartilaginous tissue was seen 7 months after treatment.

Radiographic assessment of the equine carpal joint under incremental loads and during flexion

Non-physiologic loading of the carpal bones is believed to result in osteochondral fractures, ligament rupture and axial instability in the equine forelimb; however, the mechanism of carpal damage due to non-physiologic loading of the carpus is largely unknown. To investigate carpal stability (alignment and direction of carpal bones’ movement) under load and during flexion, some previously described carpal parameters were measured on radiographs obtained from 24 equine cadaver limbs (aged 10.71±4.15 years). The limbs were transected at the antebrachial midshaft, axially loaded in a commercial press and serially radiographed under a range of incremental loads (extension) and 2 flexion positions. The extensions were measured by a 10° decrease in the dorsal fetlock angle (DFA) from 160° to 110° (DFA160 to DFA110) using the jacking system of the press; and flexions at palmar carpal angle of 45° and 90° (PCA45 and PCA90). As loading increased from DFA160 to DFA110 there was a progressive significant increase in Third Carpal bone Palmar Facet Angle (C3PalFCA: 86.46±2.54° to 88.60±2.51°) but a decrease in Dorsal Carpal Angle (DCA: 173.03±3.47° to 159.65±4.09°); Medial Carpal Angle (MCA: 186.31±1.90° to 184.61±2.26°); and Groove width of the Cr-Ci intercarpal ligament (GW.Cr-Ci ICL: 9.35±1.20° to 8.83±1.13°) while no significant differences were observed for Distal Radial Slope Carpal Angle (DRSCA) and Intermediate carpal bone Proximal Tuberosity-Radial Angle (CiPxTRA). A generalised medio-distal directional displacement in the carpal bones’ movement were observed. In conclusion, increased load on the forelimb (carpus) produced carpal hyperextension with measurable radiographic changes in the position and alignment of the carpal bones. The non-stretching (strain) or shortening of the Cr-Ci ICL during loading, indicated by the decrease in GW.Cr-Ci ICL, suggests a relaxed intercarpal ligament within a confined space which appears to absorb compressional load transferred from carpal bones and redistribution of concussion forces within the carpal joint during loading thereby providing a useful mechanism to minimise carpal damage.

Ex vivo evaluation of an alternative technique for resection of the proximal manica flexoria in horses.

To describe and evaluate an alternative technique for tenoscopic resection of the manica flexoria (MF). Descriptive study. Equine cadaver forelimbs and hind limbs (n = 36). Three surgeons varying in experience resected the MF in 12 limbs. The procedure was divided into six steps, including resection of the lateral/medial borders of the MF with a hook knife and resection of the proximal border with a micro scalpel. Outcomes compared between surgeons included completeness of resection, appearance of the margins of resection, appearance of the resected MF, collateral damage, and time required for resection. The MF was successfully resected in all specimens, with a median time of 14 minutes 54 seconds (range, 6 minutes 42 seconds to 43 minutes 33 seconds). Nineteen of 36 MF were categorized as symmetric, 11 of 36 MF were categorized as mildly asymmetrical, and six of 36 MF had unequal borders. No differences were detected between surgeons regarding the appearance of the MF and number of iatrogenic lesions. Five lesions were considered potentially clinically relevant; three were caused by the arthroscope in the scutum (1) and the deep digital flexor tendon (DDFT; 2), and two consisted of DDFT damage caused by the microscalpel. The MF was successfully and symmetrically resected with minimal damage to adjacent structures by surgeons with varying levels of experience. The results of this study provide evidence to justify further evaluation of the technique described here in live horses with rupture of the MF.

Equine Stereotaxtic Population Average Brain Atlas With Neuroanatomic Correlation.

There is growing interest in the horse for behavioral, neuroanatomic and neuroscientific research due to its large and complex brain, cognitive abilities and long lifespan making it neurologically interesting and a potential large animal model for several neuropsychological diseases. Magnetic resonance imaging (MRI) is a powerful neuroscientific research tool that can be performed in vivo, with adapted equine facilities, or ex-vivo in the research setting. The brain atlas is a fundamental resource for neuroimaging research, and have been created for a multitude animal models, however, none currently exist for the equine brain. In this study, we document the creation of a high-resolution stereotaxic population average brain atlas of the equine. The atlas was generated from nine unfixed equine cadaver brains imaged within 4 h of euthanasia in a 3-tesla MRI. The atlas was generated using linear and non-linear registration methods and quality assessed using signal and contrast to noise calculations. Tissue segmentation maps (TSMs) for white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF), were generated and manually segmented anatomic priors created for multiple subcortical brain structures. The resulting atlas was validated and correlated to gross anatomical specimens and is made freely available at as an online resource for researchers (https://doi.org/10.7298/cyrs-7b51.2). The mean volume metrics for the whole brain, GM and WM for the included subjects were documented and the effect of age and laterality assessed. Alterations in brain volume in relation to age were identified, though these variables were not found to be significantly correlated. All subjects had higher whole brain, GM and WM volumes on the right side, consistent with the well documented right forebrain dominance of horses. This atlas provides an important tool for automated processing in equine and translational neuroimaging research.

Elastic properties of collateral and sesamoid ligaments in the forelimbs of equine cadavers

To evaluate the elastic modulus of various ligaments of the forelimbs of cadaveric horses. 408 ligaments from 37 forelimbs of 10 Thoroughbred cadavers and cadavers of 9 other horse breeds. Collateral ligaments and straight and oblique sesamoid ligaments were harvested from the proximal interphalangeal, metacarpophalangeal, carpal, and elbow joints of both forelimbs of all 19 horses. Ligament dimensions were measured, and the elastic modulus was determined by tensile testing the ligaments with a strain rate of 1 mm•s-1. Elastic modulus of the ligaments differed significantly among joints. Highest mean ± SE elastic modulus was for the medial collateral ligament of the metacarpophalangeal joints of Thoroughbreds (68.3 ± 11.0 MPa), and the lowest was for the lateral collateral ligament of the elbow joints of other breeds (2.8 ± 0.3 MPa). Thoroughbreds had a significantly higher elastic modulus for the collateral ligaments of the proximal interphalangeal and metacarpophalangeal joints, compared with values for the other breeds. There was large variation in elastic modulus. Elastic modulus was negatively affected by age. In the ligaments in the distal aspect of the forelimbs, elastic modulus was negatively affected by height at the highest point of the shoulders (ie, withers). Cross-sectional area and elastic modulus of collateral ligaments in the forelimbs of equine cadavers differed between breeds and among joints, which may have been reflective of their relative physiologic function under loading during exercise.

Risk of intra-articular injection with longitudinal ultrasound-guided injection of collateral ligaments of the equine distal interphalangeal joint.

Desmopathy of the collateral ligaments of the distal interphalangeal joint is a common cause of equine foot lameness and carries a poor prognosis with conservative management. Intralesional injections may improve healing, although accuracy of radiographically guided injections is significantly less than when guided by MRI, which requires special needles. Longitudinal ultrasound-guided injection of the distal collateral ligament has not been evaluated objectively. In this prospective, anatomic study, seven equine cadaver limbs (14 collateral ligaments) were injected with methylene blue dye and radiographic contrast medium using ultrasound to guide the needle longitudinally into the collateral ligaments until contacting bone. The insertion site of the needle proximal to the coronary band was measured on the limb and the needles left in place for radiography and CT to evaluate the needle angulation, location of the contrast medium, and whether the contrast entered the distal interphalangeal joint. The limbs were frozen and sectioned with a band saw to identify the location of the dye. Fifty percentage of injections were in or around the collateral ligaments. However, the percentage of "successful" injections, defined as in the collateral ligament but not in the joint, was only 36%. All legs had dye and contrast in the joint after both ligaments had been injected. There were no significant differences between the needle angle and entry site for "successful" and "unsuccessful" injections. Findings from this study indicates that the success rate is low for injecting the distal portions of the distal interphalangeal joint collateral ligaments using ultrasound guidance alone.

Ex Vivo Comparison of the Accuracy of a Clamped with a Hand-Held Drill Guide for Drilling Distal Third Metacarpals and Metatarsals in Equids.

The aim of this study was to determine whether a clamped drill guide can be used effectively to drill across equine distal third metacarpals and metatarsals and to compare accuracy and speed of a drilling with a hand-held drill guide. Eighty equine cadaver limbs were divided between four surgeons with varying experience. The limbs were randomly allocated to clamped or hand-held drill guides and placed in a stand in an upright/standing position on a metal table. Drilling times from cis- to trans cortices were measured. Post-drilling computed tomography images were used to assess drilling deviations in the dorsopalmar and proximodistal directions. Mean proximodistal deviation of the drill hole was distad for both guides and significantly (p = 0.01) less for the clamped drill guide +0.35° (range: -5.42°, +6.61°, standard deviation [SD] ± 3.18°) than the hand-held drill guide +2.05° (range: -5.24°, +9.81°, SD ± 3.69°). Mean dorsopalmar/plantar deviation was non-significantly (p = 0.17) less for the clamped drill guide -0.27° (range: -9.72°, +6.58°, SD ± 3.57°) than the hand-held drill guide +0.60° (range: -9.74°, + 12.33°, SD ± 4.51°). Mean time taken to drill from cis to trans cortex was significantly (p < 0.001) shorter with the clamped drill guide (41.2s) than the hand-held guide (56.6s). The clamped drill guide could be used successfully on the equine distal third metacarpals and metatarsals and resulted in some improved accuracy and reduced drilling time compared with the hand-held guide. The use of the clamped drill guide in vivo could be supported. This may be of benefit for certain fracture repairs in equids.

An equine cadaver study investigating the relationship between cervical flexion, nuchal ligament elongation and pressure at the first and second cervical vertebra

Pressure in the atlanto-axial region due to hyperflexion (‘rollkur’) may influence the development of a nuchal bursa, as adventitious bursae may be caused by pressure. Investigating the pressure between the nuchal ligament and atlas/axis in a flexed position may provide information on the pathogenesis of nuchal bursitis. In this study, ten equine head and neck specimens with one side of the soft tissues over the cervical vertebral spine removed were placed in lateral recumbency on a table in neutral, mildly flexed, and hyperflexed head and neck positions. Angulations of the neck were measured using markers placed on the nuchal ligament and drilled into the skull, vertebrae and withers. In six specimens, the pressure between the nuchal ligament and the atlas and the axis was measured using an inflatable air pouch.Hyperflexion was associated with the highest nuchal ligament length and with the highest pressure values at the site of the nuchal bursa over the atlas (99±24mmHg, more than four times the pressure in the neutral position) and over the axis (77±30mmHg, more than twice the pressure values of the neutral position). Also, over the three head and neck positions, neck flexion angles were highly correlated with pressure values and with nuchal ligament length. This marked increase in pressure at the level of atlas and axis caused by head and neck hyperflexion should be considered during training of horses at risk of, or diagnosed with, nuchal bursitis.