Navicular Disease Research Articles

Painful accessory navicular syndrome: A modified Kidner procedurenavicular

Objectives Painful accessary navicular syndrome is treated by various surgical methods after failed conservative treatment. The reason for the persisting pain, in all the surgically intervened cases, was degeneration of tibialis posterior tendon due to the need for dissecting the tendon in all the operative techniques described till date. So the surgical intervention for a painful accessary navicular syndrome should be done without disturbing the tibialis posterior tendon. Material and Methods We are presenting a surgical technique modifying the Kidner procedure while avoiding any damage to tibialis posterior tendon and a case series using our technique 11 patients underwent this procedure, of which ten were available for at least a two-year follow-up. Results The American orthopaedic foot and ankle society (AOFAS) ankle-hind foot score improved from 70 to 95 in the three-month follow-up and maintained till the final follow-up. Conclusion This modified Kidner procedure could be an effective technique in preventing persisting pain following the surgical treatment of the painful accessory navicular syndrome.

Rare Case Report: Radiologic Findings of Stress Fracture and Avascular Necrosis of the Type 2 Accessory Navicular Bone

The accessory navicular bone (ANB) is one of several accessory ossicles of the foot and is considered as a normal anatomic and radiographic variant (1). It occurs due to failure of fusion of a secondary ossification centre within the navicular bone. Fewer than %1 of ANBs are symptomatic, and most of symptomatic ANBs are type II ANBs. Stress fracture of the type II ANB is a rare cause of symptomatic accessory navicular syndrome. We report a case of stress fracture and avascular necrosis of the type II ANB on radiographs and magnetic resonance images in a 23- year- old male.

Equine bone marrow MSC-derived extracellular vesicles mitigate the inflammatory effects of interleukin-1β on navicular tissues in vitro.

Safe, efficacious therapy for treating degenerate deep digital flexor tendon (DDFT) and navicular bone fibrocartilage (NBF) in navicular horses is critically necessary. While archetypal orthobiologic therapies for navicular disease are used empirically, their safety and efficacy are unknown. Mesenchymal stem cell-derived extracellular vesicles (EV) may overcome several limitations of current orthobiologic therapies. To (1) characterise cytokine and growth factor profiles of equine bone marrow mesenchymal stem cell (BM-MSC)-derived extracellular vesicles (BM-EV) and (2) evaluate the in vitro anti-inflammatory and extracellular matrix (ECM) protective potentials of BM-EV on DDFT and NBF explant co-cultures in an IL-1β inflammatory environment. In vitro experimental study. Cytokines (IL-1β, IL-6, IL-10, IL-1ra and TNF-α) and growth factors (TGFβ1, VEGF, IGF1 and PDGF) in equine BM-EV isolated via ultracentrifugation and precipitation methods were profiled. Forelimb DDFT and NBF explant co-cultures from seven horses were exposed to media alone, or media containing 2 × 109 ± 0.1 × 109 particles/mL or 10 μg/mL BM-EV (BM-EV), 10 ng/mL interleukin-1β (IL-1β), or IL-1β + BM-EV for 48 h. Co-culture media IL-6, TNF-α, MMP-3, MMP-13 concentrations and explant sulphated glycosaminoglycan (sGAG) content were quantified. IL-6, IGF1 and VEGF concentrations were 102.1 (37.61-256.2) and 182.3 (163.1-226.3), 72.3 (8-175.6) and 2.4 (0.1-2.6), 108.3 (38.3-709.1) and 211.4 (189.1-318.2) pg/mL per 2 × 109 ± 0.1 × 109 particles/mL or 10 μg/mL 10 μg of BM-EV isolated via ultracentrifugation and precipitation methods, respectively. Co-culture media MMP-3 in BM-EV- (p = 0.03) and BM-EV + IL-1β-treated (p = 0.01) groups were significantly lower than the respective media and IL-1β groups. DDFT explant sGAG content of BM-EV (p = 0.003) and BM-EV + IL-1β groups were significantly higher compared with IL-1β group. Specimen numbers are limited, in vitro model may not replicate clinical case conditions, lack of non-MSC-derived EV control group. Equine BM-EV contains IL-6 and growth factors, IGF1 and VEGF. The anti-inflammatory and ECM protective potentials of BM-EV were evident as increased IL-6 and decreased MMP-3 concentrations in the DDFT-NBF explant co-culture media. These results support further evaluation of BM-EV as an acellular and 'off-the-shelf' intra-bursal/intrasynovial therapy for navicular pathologies.

Joint Stress Analysis of the Navicular Bone of the Horse and Its Implications for Navicular Disease.

The horse's navicular bone is located inside the hoof between the deep flexor tendon (DDFT) and the middle and end phalanges. The aim of this study was to calculate the stress distribution across the articular surface of the navicular bone and to investigate how morphological variations of the navicular bone affect the joint forces and stress distribution. Joint forces normalised to the DDFT force were calculated from force and moment equilibria from morphological parameters determined on mediolateral radiographs. The stress distribution on the articular surface was determined from the moment equilibrium of the stress vectors around the centre of pressure. The ratio of the proximal to the distal moment arms of the DDFT, as well as the proximo-distal position and extent of the navicular bone, individually or in combination, have a decisive influence on the position and magnitude of the joint force and the stress distribution. If the moment arms are equal and the bone is more proximal, the joint force vector originates from the centre of the joint surface and the joint load is evenly distributed. However, in a more distal position with a longer distal moment arm, the joint force is close to the distal edge, where the joint stress reaches its peak. Degenerative navicular disease, which causes lameness and pathological changes in the distal portion of the bone in sport horses, is likely to be more severe in horses with wedge-shaped navicular bones than in horses with square bones.

A review of radiographic interpretation of the navicular bone

Navicular syndrome (also called navicular disease) plays a major role in the equine industry as a chronic, degenerative and often career-limiting disease process which affects a variety of breeds of horses. In addition to clinical signs and diagnostic analgesia, diagnostic imaging plays a key role in identification of this disease process – radiography is the most used imaging modality. In addition to their clinical utility, foot radiographs are a standard element of most pre-purchase examinations. Good radiographic quality and positioning are necessary for accurate interpretation. Radiographic lesions of the navicular bone such as sclerosis, enlarged synovial invaginations, distal border fragments and flexor cortical erosions are important to identify and understand because of their potential role in the disease process. This article reviews an approach to radiological evaluation and interpretation of lesions affecting the navicular bone.

A role of therapeutic shoe in management of chronic laminitis & navicular disease: A review of 37 cases

A role of therapeutic shoe in management of chronic laminitis & navicular disease: A review of 37 cases

Radiological features of arterial channels in the equine third phalanx measured using a novel customized software represent changes of laminitis.

To identify and measure radiolucencies at the solear margin of the distal phalanx in radiographs of healthy and laminitic hooves. Clinical records and dorsoproximal-palmarodistal radiographs of equine forelimbs with radiological diagnoses of either laminitis (n = 40, L) or navicular syndrome (n = 40, NS). Outlines of the radiolucent structures at the solar margin were drawn in ImageJ, and a customized novel plugin "Arteries Analyzer/ImageJ" was used for measurements. The diverging radiolucencies outside the terminal arc of the distal phalanx were differentiated as arterial channels (open at the solear margin) and ellipses (closed at the solear margin). Comparisons between L and NS, between distal phalanges with and without ellipses, and of arterial channels and ellipses in areas were compared using Wilcoxon and the Mann-Whitney U tests, respectively. The reliability and repeatability of the method were tested using Friedman's test. Fewer arterial channels but more ellipses were identified in L than in NS. In phalanges with ellipses (n = 47), the number of ellipses and the number of arterial channels were negatively correlated (PCC -0.181, P = .224). The number of ellipses correlated positively with the severity of laminitis (PCC 0.495, P < .001; n = 80) and with the degree of rotation of the distal phalanx (PCC 0.392, P < .001; n = 80). The software tool successfully measured arterial channels and ellipses outlined by the evaluators. Results indicate that healthy arteries develop into pathological ellipses in laminitic feet. This may be used to complement the interpretation of radiographs and support clinical decision-making.

Assessment of calcium, phosphorus, magnesium, vitamin D and PTH levels in sera of lame horses.

Minerals play vital roles in physiologic processes. Calcium, phosphorus and magnesium are common minerals. Secretion, absorption and homeostasis of these minerals are affected by associations between the active vitamin D and parathyroid hormone (PTH). The aim of this study was to assess concentrations of vitamin D, PTH and minerals, such as calcium, phosphorus and magnesium in horse sera, as well as associations of these values with lameness in horses. In the references, the reasons for lameness can be deficiency and imbalance of minerals, and clinical observations also confirm this and there is still not enough information regarding the relationship between mineral imbalance and lameness of horses. The prominent forms of lameness include navicular syndrome, back pain, splints, ring bone, side bone, non-infectious arthritis and bucked shins. Deficiency and inadequacy of calcium, phosphorous and magnesium have been regarded as predisposing and aggravating factors of the aforementioned diseases. This cross-sectional study was carried out on 60 horses, including 30 lame and 30 healthy adult horses, summer to fall 2021. Levels of calcium, phosphorus, magnesium, vitamin D and PTH were assessed in sera using automatic analyser, atomic absorption spectroscopy and commercially available kits. The average level of calcium was higher healthy horses than lame horses in the two seasons (p<0.001). The average level of inorganic phosphorus in horses was higher in summer than autumn (p<0.001). The mean magnesium concentration in healthy horses was greater than lame horses in the two seasons (p<0.01). In this study, the mean PTH concentration in healthy horses was lower in fall than summer (p<0.05). The low average levels of calcium and magnesium in lame horses in the two seasons indicate critical roles of calcium and magnesium in the normal function of the horse musculoskeletal system as well as prevention of lameness.

Novel holistic pharmacokinetic model applied to plasma and urine concentrations of 2,5-dihydroxybenzene sulphonate following administrations of calcium dobesilate and etamsylate to exercised horses.

Calcium dobesilate (CD) is a synthetic venoactive drug used in veterinary medicine to treat equine navicular disease. Etamsylate is a haemostatic agent used in horses for the treatment of exercise-induced pulmonary haemorrhage. Both etamsylate and CD dissociate in the circulatory system with 2,5-HBSA as the active drug. The aim of the research was to be able to provide detection time (DT) advice from pharmacokinetic (PK) studies in Thoroughbred horses to better inform trainers, and their veterinary surgeons, prescribing these substances for treatment of Thoroughbred racehorses. Two (pilot study) and six (final study) horses were given 28 and 9 repeated dose of CD (3 mg/kg BID) respectively. Two horses were each given a single intravenous (IV) dose of etamsylate (10 mg/kg). Plasma and urine 2,5-HBSA concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The CD pilot study revealed that steady state could be reached with a few days and that 2,5-HBSA in plasma and urine shows instability during storage at -20°C but appears stable at -80°C. A novel holistic non-linear mixed-effects three-compartmental PK model was developed that described both plasma and urine concentrations of 2,5-HBSA, from either CD or etamsylate administration. Typical values for 2,5-HBSA clearance and bioavailability were 2.0 mL/min/kg and 28% respectively. Using the parameters obtained from this PK model, in conjunction with methodology developed by Toutain, afforded a possible screening limit (SL) that can regulate for a DT of 3 days in urine; however, a corresponding SL in plasma would be below current levels of detection. However, it is the responsibility of the individual racing authorities to apply their own risk management with regard to SLs and DTs.

Interleukin-1β and methylprednisolone acetate demonstrate differential effects on equine deep digital flexor tendon and navicular bone fibrocartilage cells in vitro

To investigate the effects of interleukin-1β (IL-1β) and methylprednisolone acetate (MPA) on equine intrabursal deep digital flexor tendon (DDFT) and navicular bone fibrocartilage (NBF) cells in vitro. Third passage DDFT and NBF cells from 5 healthy donor horses ages 11-17 years euthanized for reasons unrelated to musculoskeletal conditions. Aggregate cultures were incubated with culture medium alone (control), 10 ng/mL IL-1β, 10 ng/mL IL-1β + 0.05 mg/mL MPA, or 10 ng/mL IL-1β + 0.5 mg/mL MPA for 24 hours. Extracellular matrix (ECM) gene expressions were assessed via real-time polymerase chain reaction (rtPCR). Culture media matrix metalloproteinase (MMP) -3 and -13 concentrations were quantified via ELISA. Total glycosaminoglycan (GAG) content in the cell pellets and culture media was also assessed. IL-1β and IL-1β combined with MPA significantly downregulated ECM gene expression to a greater extent in NBF cells compared with DDFT cells. IL-1β and IL-1β combined with MPA significantly upregulated MMP-3 culture media concentrations in DDFT cells only, and MMP-13 culture media concentrations to a greater extent in NBF cells compared with DDFT cells. NBF cells were more susceptible to IL-1β and MPA-mediated ECM gene expression downregulation in vitro. These results serve as a first step for future work to determine intrabursal corticosteroid regimens that limits or resolve the inflammation as well as take into consideration NBF cell biosynthesis in horses with navicular disease, for which currently no information exists.

Os Navicular Syndrome: A Symptomatic Accessory Ossicle of the Foot

Accessory navicular bone occurs due to failure of fusion of a secondary ossification center with the navicular. It is the second most common ossicle of the foot, with majority of them being identified incidentally on imaging studies. We report a case of 45-year-old female who presented with complaints of pain and localized redness over the medial aspect of the right foot which was aggravated on walking. This brief review aims to describe the pathophysiology, radiographic findings and management of Os naviculare syndrome. We also wish to highlight to the physicians that it must be suspected in patients with localized painover the medial aspect of the midfoot without obvious trauma. The presence of accessory navicular should not be disregarded as an incidental radiological variant in a symptomatic patient.

Systematic Review of Complementary and Alternative Veterinary Medicine in Sport and Companion Animals: Extracorporeal Shockwave Therapy.

Extracorporeal shockwave therapy (ECSWT) is increasingly used to treat different types of musculoskeletal conditions in sport and companion animals. To explore the scientific basis for the treatment, we conducted a systematic review of the literature on ECSWT used in horses, dogs, and cats. Relevant articles published in 1980-2020 were identified from three major databases. Each article was assessed for risk of bias. The review identified 27 relevant articles on the effects of ECSWT in horses, nine in dogs, but none in cats. Typically, ECSWT involved one to three treatment sessions at 1- to 3-week intervals. We identified studies on bone mass and bone healing, wound healing, navicular disease, ligament injury, desmitis, sesamoiditis, tendon injury, osteoarthritis, and short-term analgesic effects. Common to all indications was that the scientific evidence was very limited. For each separate indication, there were relatively few studies, many of which had methodological flaws. Where favorable results were reported, they were usually not replicated in independent studies. A few encouraging results were found. In sport and companion animals, the scientific evidence for clinical effects of ECSWT in horses, dogs, and cats is limited. For some applications, notably short-term pain relief, ligament ailments, and osteoarthritis, the results seem promising and warrant further exploration in high-quality studies.

Equine shock wave therapy - where are we now?

Over the past three decades, electrohydraulic extracorporeal shock wave therapy (ESWT) as a treatment modality for equine orthopaedic disorders has sparked exponential interest among practitioners, but its clinical applications are quickly evolving and a current review highlighting modernised equine clinical use is lacking. The objective of this review is to summarise the most current ESWT technology, evidence for its use, proposed mechanisms of action and clinical applications in horses while also highlighting the areas requiring further investigation. The three ways to generate a shock wave are through electrohydraulic, electromagnetic or piezoelectric mechanisms, but over the last decade, electrohydraulic systems have predominated due to the ability to focus and control a therapeutic waveform. Shock waves' primary physical effect is believed to be via mechanotransduction leading to cellular activation and downstream signalling. Experimentally, ESWT's effects on osseous, connective tissue and wound healing via various mechanisms of action have been reported both in the human and veterinary literature. Clinical trials have investigated ESWT's orthopaedic application including osteoarthritis, thoracolumbar pain, navicular syndrome, tendinopathy and proximal suspensory desmopathy, with its concomitant use with biologics representing an area of active research. Direct ESWT protocol comparisons in terms of long-term efficacy with variables of energy, depth and exposed tissue types are still lacking with evidence-based recommendations being largely anecdotal. Technical advancements to facilitate the safe and judicious use of ESWT include human and equine hearing protection, light sedation and/or patient restraint. Efforts to ensure the safe and judicious use of ESWT and its analgesic effects are ongoing.

Clodronate detection and effects on markers of bone resorption are prolonged following a single administration to horses.

Clodronate is a potent antiresorptive agent labelled for use in horses over 4 years of age, for the treatment of navicular syndrome. Concerns regarding the extra-label use of clodronate in equine athletes, such as racehorses, have been raised as inhibition of osteoclast activity by clodronate has been postulated to interfere with normal bone healing, which is imperative to the repair of microfractures. The paucity of data describing the long-term pharmacokinetics of clodronate and effects on biomarkers of bone resorption necessitates further study. (1) To determine clodronate concentrations in blood and urine over a 6-month period in horses undergoing treadmill exercise and (2) to assess the effects of clodronate on protein biomarkers of bone remodelling in this same group of horses. Randomised controlled experimental study. Seven exercised Thoroughbred horses received a single im administration of 1.8mg/kg clodronate and four horses received an equivalent volume of saline. Blood and urine samples were collected prior to, during and for 182 days post drug administration for drug concentration determination using liquid chromatography-tandem mass spectrometry, and determination of protein biomarker (CTX-1 and TRAcP5B) concentrations. Clodronate was detectable in blood for 14-175 days and for up to 175 days in urine. For some horses, concentrations were nondetectable at one time point but detectable at a subsequent time point. The terminal serum half-life ranged from 1.80 to 283.9 days. CTX-1 concentrations were significantly higher, relative to baseline, in both treated and control groups while concentrations of TRAcP5B were significantly lower in the treated group. Relatively small number of horses studied. Based on assessment of protein biomarkers, clodronate appears to influence osteoclasts at label doses. Furthermore, results of this study support racing regulations that preclude horses administered bisphosphonates for medical reasons, from racing for a prolonged period of time.

Complementary biomarker detection for bisphosphonate use in racehorses

Determining the use of off-label bisphosphonates (BPs) in young horses (< 4 years old) is of interest due to the threat to racing integrity and welfare associated with this class of drugs that have the potential to manipulate bone structure. The analysis of BPs in biological matrices is challenging by liquid chromatography coupled to mass spectrometry (LC-MS/MS) and alternative sample preparation approaches are needed to detect their misuse in racehorses. There are currently two classes of BPs: non-nitrogen and nitrogen-containing with each having a distinct mode of action. Currently two non-nitrogenous based BPs are available for use in horses, tiludronic acid (or tiludronate) and chlodronate for the treatment of navicular syndrome (Mitchell et al. BMC Veterinary Research 2019;15(1):211) in horses over the age of 4. There is, however, evidence that BPs can persist in the bone for several years after administration since they can form hydroxyapatite crystals prior to being fully absorbed by active osteoclasts where full inhibitory action is performed (Riggs et al. Equine veterinary journal 2021;53(6):1287–1295). Therefore, with this prolonged detection time for the BPs, it is necessary to investigate whether the use of metabolomic biomarkers can provide a complementary method for the detection of their misuse. The aim of this research was to develop a biomarker approach for complementary direct detection of bisphosphonate drugs in equine plasma. BPs are hydrophilic therefore the targeted detection of tiludronic acid in equine plasma required an orthogonal solid phase extraction (SPE) method using both a polymeric reversed-phase sorbent and a weak anion exchange cartridge prior to derivatisation using trimethyl orthoacetate and reverse LC-MS/MS. Endogenous lipids and corticosteroids in equine plasma were detected after protein precipitation and SPE with a polymeric reverse phase cartridge prior to liquid chromatography high-resolution mass spectrometry. Data was analysed using the Shimadzu Insight Explore software to determine up- or down-regulation of biomarkers. Results were then profiled using a Parametric Empirical Bayes algorithm to propose individual reference limits (IRLs). Tiludronic acid was detected up to the final collection point of 28 days post-administration. Following a targeted approach, up- and down-regulation of the eicosanoid and corticosteroid ratios were observed with the corticosteroid ratio exceeding both the proposed population reference limit (PRL) and IRL. Using a semi-targeted approach, several additional lipids were identified to have activity during the administration and will require further confirmatory analysis. Monitoring the impact on endogenous biomarkers following an administration of Tiludronic Acid in racehorses is limited therefore little is known if BPs have a direct or indirect effect on the inflammatory pathways. However, research in humans has linked BPs with possible effects of analgesia in addition to bone remodelling that BPs are primarily used for. Therefore, it is necessary to further extend detection capabilities to ensure endogenous eicosanoids and corticosteroids are monitored. This, however, should not negate the need for the detection of the drug itself as tiludronic acid has the potential to be detected as far as 28 days post-administration. Therefore, a complementary biomarker approach would be preferable for the detection of non-nitrogen-based BPs, which can be further applied for the nitrogen-based BPs. A complementary biomarker approach to direct detection of administered drugs can improve the understanding of effect and support non-targeted detection strategies for analogues of specific drug classes.

Use of a novel helical fan beam imaging system for computed tomography of the distal limb in sedated standing horses: 167 cases (2019-2020).

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with a range of clinical distal limb problems. 167 horses. Medical records were reviewed of horses presented for CT of the distal limb at 2 university-based veterinary hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging. Most horses were Thoroughbreds and Quarter Horses. Procedure times ranged from 15 to 40 minutes, with scanning completed in 15 to 45 seconds for each region of interest. The foot or pastern region was commonly scanned (88/167 [53%] horses), with navicular bone disease diagnosed in 42 of 88 (48%) horses. The fetlock region was also commonly scanned (42/167 [40%] horses), with palmar or plantar osteochondral disease diagnosed in 17 of 42 (40%) horses. Horses were compliant during scanning, and no complications with sedation or damage to the scanner occurred. A specific imaging diagnosis for the lameness was achieved more frequently with CT imaging (166/167 [99%]) than with planar digital radiography (26/58 [45%]). The helical fan beam CT system could be used safely to scan sedated standing horses from the carpal or tarsal region distally. Subjectively, the machine was easy to operate, allowing CT to be incorporated into lameness investigations. CT imaging was very likely to result in a clinical diagnosis in horses with distal limb lameness.

Equine Podotrochlear Apparatus - Histologic Characterization

Background: The navicular syndrome may be associated with alterations in other podotrochlear apparatus components, such as the deep digital flexor tendon, collareral sesamoid and distal sesamoid ligaments, podotrochlear bursa and distal sesamoid bone. However, the clinical significance and nature of these changes are not well understood, many of descriptive reports about distal sesamoid bone lesions are rarely accompanied by a complete and comprehensive comparison with animals of the control group. The aim of this study was to described histologically findings of the podrotrochlear apparatus components, allowing the understanding of the inserts and their microscopic appearance, thus providing the future recognize of their alterations.Materials, Methods &amp; Results: Fourteen samples of the podotrochlear apparatus were taken out of 44 equine thoracic limbs specimens, separated at the radiocarpal joint of Crioulo and Thoroughbred horses, with an average age of 6.0-year-old, coming from a private clinic in southern Brazil. The thoracic limbs specimens were refrigerated at 4ºC at the clinic and then they were sent to the University Federal of Santa Maria (UFSM). Once at the University laboratory, the specimens were dissected to isolate the podotrochlear apparatus from each one. Subsequently, transversal and longitudinal samples from the distal sesamoid bone, deep digital flexor tendo, distal sesamoid ligament, colateral sesamoid ligament, were collected and podotrochlear bursa which were processed at the Veterinary Pathology Laboratory of the UFSM and University Federal of Santa Catarina (UFSC). The tissues samples were fixed in a 10% formaldehyde solution for 14 days and routinely processed for histology. The samples were sectioned at 3 µm and stained using the hematoxylin-eosin (H-E) routine method. The bone samples, after fixation, underwent a decalcified process in a formic acid-sodium citrate aqueous solution and routinely processed for histopathology. Histologic tendons evaluation showed that it is arranged in honeycombs fascicles in a transverse section observation. The tendinous fibers have a more compact and aligned collagen fibers arrangement due to the dense connective tissue. The synovial membrane of the podotrochlear bursa is composed of a cubic pseudo conjunctival epithelium arranged with a layer of synoviocytes forming villi towards the lumen. This characterization is very similar to that of the synovial joint membrane. The collateral sesamoid ligament fibers are not perfectly aligned, occurring at their confluence in some areas accompanied by the dissection of adipose tissue. The distal sesamoide ligament fibers, composed by of loose connective tissue associated with synoviocytes and vascular stroma. The articular surface of the distal sesamoid bone is arranged in 3 layers of chondrocytes embedded in a hyaline matrix. There was a clear differentiation between the subchondral bone area and the fibrocartilage tissue in the palmar aspect of the distal sesamoid bone.Discussion: The morphophysiological characterization of the podotrochlear structures inside the hoof capsule it is important for the future recognition of abnormalities and the possible hypothesis that originates the podotrochlear syndrome. These changes have great clinical relevance and very often associated of distal limb lameness in horses. The normal macroscopic, ultrasonographic and radiographic images along with the histomorphometric study of the podotrochlear structures have contributed for the morphophysiological comprehension and consequently future interpretation of the podotrochlear structures diseases.Keywords: podotrochlear apparatus, distal sesamoide bone, deep digital flexor tendon, navicular syndrome, histological findings.

Arthroereisis: Treatment of Pes Planus.

Arthroereisis is a surgical procedure primarily used to treat flexible pes planus (flatfoot) in pediatric and young adult patients. The principal goal of subtalar arthroereisis is to relieve pain and restore function. This is primarily done by restoring the medial foot arch without fusing the subtalar joint and without requiring a long recovery period needed after osteotomies. Although the procedure can be performed in isolation to treat flexible flatfoot, it can also be performed as an ancillary in the treatment of tarsal coalition, posterior tibial tendon dysfunction, and accessory navicular syndrome. Various implants and multiple surgical techniques exist for arthroereisis, such as the sinus tarsi implant and calcaneo-stop. The type of device and the surgical approach to proceed with are based on the surgeon’s discretion rather than an evidence-based protocol. Multiple complications can arise from subtalar arthroereisis, most commonly sinus tarsi pain. Currently, there is a dearth of quality clinical data and evidence on the long-term outcomes and complications of arthroereisis. This lack of literature for a commonly performed procedure validates the need for future studies to better guide a standard protocol, reach consensus on well-defined indications and contraindications, provide expected complications, and improve the practice of evidence-based medicine.

Morphometric Study of the Navicular Bone in a Nigerian Population: A Direct Measurement Study

Background: The human foot, containing approximately 26 bones, is highly developed for movement, balance, and weightbearing. It is modified into medial longitudinal, lateral longitudinal, and transverse arches which, in addition to the above functions, play a role in protecting the plantar tissues and neurovascular structures. Morphometry of the navicular bone, one of the bones of the foot that plays an important role in the medial longitudinal arch, was investigated in this study. Methods: One hundred fifty adult dry navicular bones were used. Navicular breadth, height, maximum thickness, maximum talar facet height and breadth, maximum cuneiform facet height and breadth, and maximum navicular tuberosity projection height were measured using digital Vernier callipers. The anatomical features were used to determine the side. Bones with features that suggested previous fractures or any previous disease were excluded from this study. Ethical approval was obtained from the Research Ethics Committee of the Department of Anatomy, Ebonyi State University, Abakaliki, Nigeria. Results: The navicular bone showed great variations in its left and right sides, with the values of the dimensions on the left being higher than the right. Conclusions: An understanding of these variations will be helpful to medical scientists, osteologists, and orthopedic surgeons during surgical interventions on navicular bone fracture and accessory navicular syndrome.

Contrast Enhanced Computed Tomography Findings in 105 Horse Distal Extremities

The poor soft tissue conspicuity of CT can be improved by using intra-arterial CT Angiography (CTA), and intra-articular and intra-bursal contrast enhanced CT (CTAR). This retrospective study describes a combination protocol of CT and CTA of the horse's foot, and CTAR of the distal interphalangeal joint and navicular bursa. It is hypothesized this would provide a comprehensive overview of the range and severity of distal limb pathology. Radiology reports of all horses admitted for distal limb CT over a 5 year period were reviewed. All horses with a complete four stage CT examination and radiology report with lameness isolated to the foot were included. Twenty seven imaging findings using a four grade semiquantitative severity scoring system contributing towards six main diagnostic categories were described. One hundred and five examinations on 56 horses revealed a diagnosis of navicular bone disease in 64%, deep digital flexor tendinopathy in 43%, distal interphalangeal osteoarthritis in 35%, navicular bursitis in 31%, distal interphalangeal collateral ligament desmopathy in 26%, and hoof capsule and distal phalanx pathology in 10%. Only 25% of the navicular bone disease cases were considered clinically significant. The majority of deep digital flexor tendon lesions (77%) and distal interphalangeal joint osteoarthritis (51%) were considered significant. Approximately one third of navicular bursa (37%) and collateral ligament (33%) abnormalities were considered significant. Navicular bursa abnormalities were associated with navicular bone and deep digital flexor tendon lesions. The findings support the hypothesis and the use of this protocol for evaluation of foot lameness.