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Background Correct diagnosis and characterisation of deep digital flexor tendon (DDFT) lesions in equine athletes allows targeted treatment and improved prognostication. Objectives To assess the prevalence and character of pathological change within the DDFT in the pastern with concurrent tendon injury distally. It is hypothesised that tendon lesions in the pastern will be associated with tendinopathy within the hoof capsule. Study design Retrospective descriptive case series. Methods Cases with DDFT lesions in the pastern and magnetic resonance imaging (MRI) or ultrasonography of the foot were evaluated retrospectively. Lesion location and type were recorded. Odds ratios were calculated to determine the associations between more distal tendinopathy and the presence of different DDFT lesion types in the pastern. Results Thirty-four MRI scans of 33 horses and 64 ultrasonographic exams of 58 horses were analysed. Lesion location and type were recorded. Distal DDFT lesions were found in 75% (95% CI: 66.0-84.0) of total cases of pastern DDF tendinopathy and in 97% (95% CI: 91.6-100.0) of cases with core lesions of the DDFT in the pastern. A core lesion in the pastern was significantly more likely (OR = 20.7, 95% CI: 2.2-191.0; P = .008) to be associated with injury in the foot than other types of pastern lesion. Main limitations MRIs of the foot were not obtained on all included limbs which did not allow for fully inclusive evaluation of DDFT lesions distal to the navicular bone. Conclusions DDFT pathological change in the pastern, particularly core lesions, is associated with additional tendinopathy within the hoof capsule. When a DDFT lesion is found in the pastern, further imaging of the tendon within the foot is indicated to direct appropriate treatment and improve prognostication.

A 32-year-old white male was on a second-story balcony when he fell off and landed on the cement below. With initial X-rays being read as negative on the radiology report due to the subtle nature of the injury, the patient was promptly diagnosed with a medial swivel dislocation by the orthopaedic team, which ended up being fixed, unstable, and irreducible. The patient also had acute skin compromise and needed to be taken to the operating room prior to progression of skin breakdown. This dislocation pattern is a rare variant, especially when paired with the fixed nature of the dislocation and the soft tissue compromise. In the end, open treatment was necessary in order to reduce the talonavicular joint. Because of early recognition and prompt treatment, skin breakdown was avoided. Internal screw fixation of the fractured navicular bone was needed along with K-wire insertion to hold the normal anatomy of the talonavicular joint reduced. All hardware was ultimately removed after healing, and anatomy was restored with excellent patient function. This case report highlights the orthopaedic knowledge needed to not only recognize this rare fracture-dislocation pattern but to also treat it promptly when encountered.

Background Increased 18 F-Sodium Fluoride (18 F-NaF) uptake at the chondrosesamoidean ligament (ChSL) attachment on the distal phalanx was identified in an exploratory positron emission tomography (PET) study. The prevalence and significance of this lesion has not been previously investigated. Objectives The goal of this study was to assess the prevalence of this lesion, its association with other imaging findings and with clinical signs. Study design Retrospective cross-sectional analytical study. Methods All horses with 18 F-NaF PET and computed tomography (CT) imaging of the feet performed between October 2016 and December 2017 were included in the study. All PET scans were independently assessed by two radiologists for increased uptake at the ChSL attachment site and concurrent imaging was reviewed. Clinical findings, treatment and outcome were retrieved from the medical records. Results Fourteen of 30 horses (20/56 feet) had increased 18 F-NaF uptake in the region of interest. ChSL enthesopathy was the primary lesion in three horses. Other PET abnormalities included navicular bone uptake (13 feet) and ipsilateral palmar process uptake (9 feet). There was no significant association between ChSL enthesopathy and other lesions. ChSL enthesopathy was significantly associated with foot lameness. CT abnormalities at the ChSL attachment were initially identified in one foot, and retrospectively noted in another five following the results of PET imaging. Main limitations The study is retrospective and there was a limited sample size. Conclusions PET led to identification of ChSL enthesopathy in a large proportion of horses with foot pain. This finding is most commonly associated with other lesions but may also represent the main abnormality. The axial border of the palmar processes of the distal phalanx should be carefully assessed on cross sectional imaging to identify this lesion. ChSL enthesopathy may be an important but previously not recognised component of foot pathology in horses.

Introduction and importance Navicular bone location of primary subacute hematogenous osteomyelitis uncommon. There are few cases reported in literature. We aim to describe the clinico-radiological features of primary subacute hematogenous osteomyelitis of the navicular bone in a 7-year-old child, to explain our management of this rare disease and demonstrate that medical treatment without surgery is enough. Case presentation A 7-year-old child presented to emergency department. His chief complaint was fever, left limping and foot pain. The positive examination features of were painful palpation of the dorsal side of the foot and a swelling of the homolateral ankle. The erythrocyte sedimentation rate was high. The x-ray revealed a lytic lesion of the left navicular bone. The MRI findings led to the diagnosis of subacute osteomyelitis. Pain relief and normalization of inflammatory markers were obtained after 8 weeks of antibiotic therapy. Complete radiological healing was obtained after 9 months. One year after treatment, the patient was able to practice sports as previously. Clinical discussion Subacute osteomyelitis of the navicular bone in pediatric population is a rare condition. This case shows the importance of early diagnosis thanks to MRI findings and appropriate antibiotic therapy based on the endemic bacteriological profile. Conclusion The navicular bone may develop primary subacute osteomyelitis in immunocompetent child. Early diagnosis is important for prescribing effective conservative treatment., Highlights • Subacute osteomyelitis of the navicular bone is an etiology of lameness in children. • The penumbra sign on MRI is strongly suggestive of the infectious origin of the bone involvement. • Medical treatment without surgery can lead to a cure. • Antibiotic therapy should be sufficiently prolonged for at least 3 months.

We report a unique case of the total loss of the intermediate cuneiform by posttraumatic avascular necrosis resulting from a left foot open fracture and dislocation of the navicular bone and medial and intermediate cuneiforms at the Chopart and Lisfranc joints in a 64-year-old woman. The injury was managed with open reduction and internal fixation with Kirschner wires and cannulated screws. During postoperative follow-up, we observed avascular necrosis of the intermediate cuneiform and the total loss of the bone. An extensive English literature search revealed only one case report published on this topic. Thus, we provide this case study to help guide clinical decision making in the future.

BackgroundThe medial longitudinal arch angle (LAA) of the foot has been used as an index of high and low arches. The LAA during the support phase of running (LAArun), which may be related to lower-limb injuries, is commonly predicted from the LAA at standing (LAAstand). However, it is not known whether this prediction is valid for all of the foot contact patterns. The purpose of this study was to verify whether prediction of the LAArun from the LAAstand is valid for different foot strike patterns.MethodsThe 26 participants were divided into a rearfoot strike group (n = 15) and a nonrearfoot strike group (n = 11). The LAA was obtained by measuring the angle formed between the line from the navicular bone to the medial malleolus and the line from the navicular bone to the first metatarsal head. The LAAstand and the minimum value of the LAArun, when the arch is most collapsed, were measured using a motion capture system.ResultsThere were no significant differences in the LAAstand, the LAArun, and the difference (LAAstand – LAArun) between the two groups. In both groups, a very strong and significant correlation was found between the LAAstand and the LAArun. Furthermore, a nearly identical equation for predicting the LAArun from the LAAstand was derived for the two groups.ConclusionsThe LAArun can be predicted from the LAAstand for any foot strike pattern with almost the same equation.

Background Individuals' interest in sports activities has been increasing, contributing to more stress fracture occurrences in uncommon locations on the skeleton. In this study, several cases of stress fractures in atypical locations are presented, and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored. Additionally, different causes of stress fractures, as well as various modalities of treatment, are highlighted. Other potential factors of stress fractures were identified by a literature review. Case summary Six cases of stress fractures in the calcaneus, intermediate cuneiform bone, sacrum, tibia (bilateral), navicular bone and femoral neck are presented, with different types of diagnostic imaging and treatments. All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines. Conclusion The type of therapeutic procedure selected should depend on the specific clinical case, i.e., the patient's condition and level of physical activity.

Case report: We describe the radiographic and magnetic resonance imaging findings associated with a case of bilateral forelimb bipartite navicular disease in a 7-year-old Warmblood gelding used for eventing. In addition to the radiographically evident partitioned navicular bones, magnetic resonance imaging (MRI) also detected other concurrent abnormalities occurring within the foot that have not been described before in other cases of navicular bone partition. MRI not only revealed soft tissue lesions of the podotrochlear apparatus, but also allowed for more detailed characterisation of the recently diagnosed osseous navicular bone pathology. Conclusion: Knowledge of these additional changes influenced prognostication in this case and provides an explanation for why this condition usually results in such a poor prognosis for the return to previous levels of performance in athletic patients.

Introduction: In anterior transfer of the tibialis posterior tendon, the tendon was harvested using two incisions, the first at its attachment point on the navicular bone and second on the medial side of the leg above the medial malleolus. To provide the maximum tendon length, the second incision needs to be as proximal as possible but injury to the muscle origin must be avoided. The purpose of this study is to establish the location of the second incision that yields the greatest tendon length. Materials and Methods: Forty-five unpaired embalmed cadaveric legs were dissected. Demographic data, gender, age and side of specimen were recorded. The distance between the tip of the medial malleolus and the muscle origin was measured. Mobile tendon length, muscle origin, foot length, tibial length and position of ankle were also noted. Results: The mean mobile tendon length was 11.1 (range 10.7-11.4) cm and the distance between the tip of the medial malleolus and the muscle origin was 6.8 (range 6.5-7.0) cm. The mean foot length was 22.2 cm (range 21.7-22.7), tibial length was 31.5 cm (range 30.8-32.2), and muscle origin was 23.7 cm (range 21.0-26.3). The mean angle position was 46 degrees plantar flexion (range 43-49). In subgroup analysis by gender, the mobile tendon length, distance between the tip of the medial malleolus and the muscle origin, and tibial length, were significantly greater in males than females. Conclusion: For anterior transfer of the tibialis posterior tendon, an incision 7.1 cm above the medial malleolus in the male and 6.4 cm above it in the female provides the longest mobile tendon without injury to its origin. Level of Evidence: V, Cadaveric descriptive study This article is protected by copyright. All rights reserved.

Background Positron emission tomography (PET) is a cross-sectional, functional imaging modality that has recently become available to the horse. The use of 18 F-sodium fluoride (18 F-NaF), a PET bone tracer, has not previously been reported in this species. Objectives To assess the feasibility of 18 F-NaF PET in the equine distal limb and explore possible applications in the horse in comparison with other imaging modalities. Study design Exploratory descriptive study involving three research horses. Methods Horses were placed under general anaesthesia prior to intravenous (i.v.) administration of 1.5 MBq/kg of 18 F-NaF. Positron emission tomography imaging of both front feet and fetlocks was performed using a portable scanner. Computed tomography (CT) of the distal limb was performed under a separate anaesthetic episode. Bone scintigraphy and magnetic resonance imaging (MRI) were subsequently performed under standing sedation. Images obtained from PET and other imaging modalities were independently assessed and the results correlated. Results Positron emission tomography images were obtained without complication. The radiation exposure rate was similar to equine bone scintigraphy. Positron emission tomography detected focal 18 F-NaF uptake in areas where other imaging modalities did not identify any abnormalities. This included sites of ligamentous attachment, subchondral compact bone plate and the flexor cortex of the navicular bone. 18 F-NaF uptake was identified in some, but not all, osseous fragments and areas of osseous formation, suggesting a distinction between active and inactive lesions. Main limitations A small number of horses were included and histopathology was not available. Conclusions 18 F-NaF PET imaging of the equine distal limb provides useful additional information when compared with CT, MRI and scintigraphy and has the potential for both research and clinical applications in the horse. The Summary is available in Chinese - see Supporting information.

Fracture-dislocations of the tarsal navicular are rare and highly complex injuries to the midfoot. The only published data on this type of fracture are clinical case reports. These injuries are normally caused by high-energy trauma, and their pathophysiology and most appropriate treatment remain unclear. We report a clinical case of a dorsal fracture-dislocation of the tarsal navicular bone associated with a medial swivel dislocation of the Chopart joint caused by a bicycle fall in a 20-year-old healthy man. Open reduction and percutaneous pinning in a novel arrangement was performed, with an excellent outcome 18 months after the injury.

Approximately 30% of tarsal navicular stress fractures are missed by physicians because plain radiographs often show no diagnostic clues. If early diagnosis and treatment are not obtained, such fractures will become refractory and the patient will no longer be able to actively participate as an athlete. We herein describe our experience treating a 14-year-old female track sprinter with persistent foot pain. Magnetic resonance imaging 6 months after the onset of pain showed a stress fracture of the tarsal navicular bone. Computed tomography showed the tarsal navicular stress fracture as well as sclerosis at the fracture edges. We diagnosed a refractory tarsal navicular stress fracture. Conservative management in the form of non-weight-bearing cast immobilization is the standard treatment for both partial and complete stress fractures of the tarsal navicular bone. However, surgical treatment is required in refractory cases. We treated the herein-described refractory case with 6 weeks of non-weight-bearing cast immobilization. We instructed the patient to perform quad muscle training at the same time as casting. Six weeks later, follow-up computed tomography showed callus formation and disappearance of the fracture line. The patient thus began full weight bearing with daily use of arch support equipment, and we allowed her to gradually return to sports. We gradually increased her activity intensity from jogging to running. She completely and successfully returned to sports after 3 months of treatment.

Although the tendon of the tibialis posterior muscle (TPM) is high morphological variability, its insertion is not well defined in anatomy discussions. The aim of the work is to systematize the classification of tibialis posterior tendon insertion by anatomical dissection. Classical anatomical dissection was performed on 80 lower limbs (40 female, 40 male) fixed in 10% formalin solution. The morphology of the insertion of the tendon was evaluated, and the muscle was subjected to appropriate morphometric measurements. Four types of insertion were observed, the most common being Type III (35 cases - 43.75%): a triple distal attachment where the main tendon inserts to the navicular bone and the medial cuneiform bone, and two accessory bands insert to the medial, lateral, or intermediate cuneiform bone or to the metatarsal bones (II, III, IV, V) depending on subtypes (A-C). The second most common type was Type II (18 cases: 22.5%): a double distal attachment. Type IV (14 cases: 17.5%) was characterized by quadruple distal attachment and was also divided into three subtypes (A-B). The rarest type was Type I (13 cases: 16.25%), which was characterized by a single band: the main tendon inserts to the navicular bone and the medial cuneiform bone. The tendon of the TPM presents high morphological variability. Knowledge of the four particular types of insertions is essential for both clinicians and anatomists. Clin. Anat. 32:557-565, 2019. © 2019 Wiley Periodicals, Inc.

BACKGROUND Accessory navicular (AN) is a common anatomic variant that is known to cause medial foot pain. Surgery may be required for excision if conservative measures fail. Often, the medial border of the navicular is excised in addition to the AN during surgery. The purpose of this radiographic study is to determine if the presence of an AN is associated with a wider or more prominent navicular in pediatric patients compared with normal controls. METHODS This study included pediatric patients who received an initial plain anteroposterior foot radiograph between January 1, 2004 and December 31, 2012 and were between the ages of 10 and 20 years. Feet with an AN were compared with those without, while controlling for age. Male and female patients were analyzed independently. Feet with fractures, deformities, or previous surgeries were excluded. Radiographic measurements included the navicular width and the protrusion of the navicular bone medially. RESULTS A total of 592 feet were included. An AN was identified in 73 feet. Male patients were analyzed separately from females. Cases with 1 AN bone had similar-sized native navicular bones in the contralateral normal foot compared with controls with 2 normal feet (P>0.05). The presence of an AN was associated with a larger navicular width (male: P=0.02, female: P=0.02) and a larger medial protrusion percent (male: P

Introdução: O osso navicular é um dos ossos do tarso que mais raramente sofre uma fratura. Com o formato de um barco e posicionado entre a cabeça do tálus e dos três cuneiformes, desempenha um papel importante na sustentação da coluna medial do pé. Uma vez fraturado, pode ter seu diagnóstico feito através da radiografia, tomografia computadorizada, ressonância magnética ou ainda por cintilografia óssea. Objetivo: Relatar um caso incomum de fratura do osso navicular, diagnosticado apenas pela ressonância magnética. Relato do Caso: Mulher de 41 anos que após uma queda referiu dor em seu pé direito com piora ao caminhar. Apresentava dor à palpação na porção medial e dorsal do mediopé e edema. Radiografia do pé normal. A ressonância magnética apresentou traço de fratura na porção medial do osso navicular. Conclusão: Apesar de incomum, as fraturas do mediopé devem ser pesquisadas com métodos de imagem e, mesmo quando a radiografia seja normal, na continuação da sintomatologia do paciente, exames de maior acurácia devem ser realizados, tais como a TC e a RM.Palavras chave: Ossos do tarso, Fraturas ósseas, Imagem por ressonância magnéticaABSTRACT:Introduction: The navicular bone is one of the tarsal bones that most rarely suffers a fracture. Shaped like a boat and positioned between the head of the talus and the three cuneiforms, it plays an important role in supporting the medial column of the foot. Once fractured, the diagnosis can be made through radiography, computed tomography, magnetic resonance imaging, or even bone scintigraphy. Objective: To report an unusual case of fracture of the navicular bone, diagnosed only by magnetic resonance imaging. Case Report: A 41-year-old woman who, after a fall, reported pain in her right foot, which worsened when walking. He had pain on palpation in the medial and dorsal portion of the midfoot and edema. The radiograph of the foot is normal. Magnetic resonance imaging showed a fracture in the medial portion of the navicular bone. Conclusion: In spite of being uncommon, midfoot fractures should be investigated with imaging methods and, even when the radiograph is normal, in the continuation of the patient’s symptoms, more accurate tests should be performed, such as CT and MRI. Keywords: Tarsal bones, Bone fractures, Magnetic resonance imaging

Isolated fracture dislocation of navicular bone is rare. It is due to a plantar flexion compressive injury, which crushes the bone. Sometimes it may displace a part of the fractured bone from the naviculocuneiform and the talonavicular joints. We present a case report of a 37 year old male who presented with isolated fracture dislocation of navicular. Open reduction and Internal Fixation was done on the dorsal surface using Navicular plate and screws. There is always a possibility of ischaemic necrosis and post-traumatic arthritis in such cases.

Summary Reasons for performing study There are few studies on the correlations between radiographic measurements of the foot and abnormalities of specific structures found with magnetic resonance imaging (MRI). Objectives To document the relationship between radiographic measurements of the equine foot and the presence of lesions in the foot on MRI. We hypothesised that different radiographic measurements would be associated with specific lesions detected by MRI. Study design Retrospective analysis of radiographs and MRI studies. Methods Seventy-four feet from 52 lame horses were included. Twenty parameters were measured on radiographs, whereas the signal intensity, homogeneity and size of each structure in the foot were evaluated on magnetic resonance images. The data were analysed using simple linear correlation analysis and classification and regression trees (CARTs). Results Linear correlations were found between the navicular bone compacta thickness and injuries of the deep digital flexor tendon, collateral sesamoidean ligament, navicular spongiosa and navicular bone proximal border. Long-toed horses had a high incidence of lesions involving the spongiosa and proximal border of the navicular bone. Elongation of the navicular bone was associated with proximal and distal border injuries. A reduced palmar angle and increased angle between the middle and distal phalanx were observed in horses with alterations of collateral ligaments of the distal interphalangeal joint and navicular bone spongiosa, respectively. For each structure under investigation, CARTs predicting the presence of MRI pathology based on radiographic measurements had excellent performance, with >80% correct classification of cases, when using one of 3 data sources. Conclusions This study demonstrated a relationship between radiographic measurements of the foot and the presence of lesions detected on MRI, while CARTs illustrated that different radiographic measurements were associated with different MRI lesions.

Multiple myeloma is a haematological disease caused by proliferation of malignant plasma cells in bone marrow. It frequently has lytic bone lesions. However, involvement of the small bones of the hands and feet is extremely rare. We report a unique multiple myeloma patient with first recurrence in navicular bone after allogenic stem cell transplantation.

Kohler's disease is rare cause of foot pain and limping in the pediatric population. The exact etiology of Kohler's disease is unknown. It usually presents as sudden and unexplained foot pain and limping. We report a case of a 5-year-old male who presented to the Pediatric Emergency Department with foot pain and inability to bear weight for two days after overactivity and acute foot injury. The patient was eventually diagnosed with Kohler's disease (avascular necrosis of the navicular bone). Although Kohler's disease is not very common, it should be considered in the differential diagnosis of foot pain in the pediatric population, as it may prevent unnecessary tests and treatments.

This study examined the eff ectiveness of an antipronation spiral stirrup (APSS) taping technique, compared with the augmented low-Dye (ALD) technique, in controlling navicular drop (ND) and producing a lateral shift in the center-of-pressure (COP) line during the stance phase of gait. Twenty college volunteers participated in a crossover design, testing 2 taping techniques across 3 conditions. Repeated measures analysis of variance revealed that the APSS technique produced signifi cantly less ND, compared with the ALD technique, at the pre(P .05) and postexercise (P .05) conditions. The APSS technique produced signifi cantly less ND than the barefoot condition at preand postexercise (P .01) conditions. A signifi cant (P .05) lateral shift in COP was noted between 30% and 90% of the stance phase in the tape reexercise condition in the APSS technique. The APSS technique seems to be eff ective at controlling ND and preventing a medial shift of the COP during the deceleration phase of foot pronation. [Athletic Training & Sports Health Care. 2014;6(6):252-260.] Overuse lower-leg injuries, although often of uncertain etiology, are frequently affected by anatomical, mechanical, training intensity, volume, and injury type factors.1,2 The catch-all term shin splints has been used to describe a variety of conditions, including compartment syndrome, periostitis, stress fractures, nerve entrapment syndrome, and various tendinopathies.3,4 More recently, the shin splints term has been used interchangeably with an equally ambiguous, but more medically descriptive phrase, medial–tibial stress syndrome (MTSS).5 This syndrome is characterized by exercise-induced pain along the posteromedial border of the tibia, is not attributed to compartment syndrome or stress fracture,6,7 and is of idiopathic origins. A common link of these varied pathologies with abnormalities in foot position is an increased drop in the location of the navicular bone. This drop, resulting in a “fallen arch,”8 is often referred to as pes planus. In a pes planus foot, the center of pressure (COP) is deviated more medially during gait than in those with a neutrally aligned foot.9-12 Williams et al13 found that low-arched individuals have a more medial COP than those with high arches, allowing the possibility that COP may be useful in detecting changes in foot orientation throughout the stance phase of gait (heel strike through toe-off).9-13 In addition, pes planus feet have been associated with tibialis posterior dysfunction.14,15 One of the primary functions of the tibialis posterior is to contract eccentrically throughout the deceleration phase of foot pronation.16 If the tibialis posterior is dysfunctional, it cannot effectively control the force that must be transferred from the foot to the lower leg, leading to its inability to control the “falling” of the arch. This hyperpronation during gait can result in lower-leg pain,3 which supports the theory that suggests that foot overpronation, attributable to tibialis posterior muscle dysfunction, is a possible cause of MTSS.7 Several researchers13,14 have studied the effectiveness of taping or use of custom shoe inserts as an effort to control navicular drop (ND). Orthotic inserts have proven to be Ms Prusak from Maple Mountain High School, Spanish Fork; and Dr Prusak is from the Department of Teacher Education, and Dr Hunter, Dr Seeley, and Dr Hopkins are from the Department of Exercise Sciences, Brigham Young University, Provo, Utah. Received: December 9, 2013 Accepted: November 12, 2014 Posted Online: December 3, 2014 The authors acknowledge the contributions of Devin Francom, MS (Brigham Young University), for his creative use of functional statistical analyses and cubic smoothing splines, allowing for the examination of changes in the center-of

We report three patients with diagnostic imaging findings that are consistent with Mueller-Weiss syndrome. Mueller-Weiss syndrome is a rare condition that involves osteonecrosis of the navicular bone in an adult. The characteristic findings for Mueller-Weiss syndrome include a dorsomedial dislocation along with the collapse of the lateral navicular bone, resulting in a comma-shaped configuration. Through these three case studies, we aim to familiarize both foot and ankle specialists and radiologists with the diagnostic imaging findings for Mueller-Weiss syndrome.

The requirement to pack the sulcus of the equine foot as an aid to diagnostic interpretation before acquisition of dorsoproximal-palmarodistal oblique projections is debatable. The purpose of this study was to investigate the benefit of packing the sulcus in the assessment of normal anatomy. 23 cadaver limbs were radiographed in a podoblock (https://www.podoblock.com/products-page/podoblock/podoblock/) A non-packed image (NP) and a packed image (P) of the same foot were acquired. The image quality of P was graded against the reference NP by five observers, where -1=P was superior, 0=no difference between P and NP, and +1=NP was superior. Four anatomical criteria were used: the distal solar margin of the distal phalanx (DP), the vascular channels of DP, the palmar aspect of the distal interphalangeal joint and the articulation of the navicular bone with DP. A total Visual Grading Analysis Score of 0.28 indicates a preference for NP images. Packing was of benefit in only 10.8 per cent of cases. While judicious high-quality packing may be of benefit in a minority of cases, the routine packing of the sulcus in equine radiography was not found to be of benefit in the assessment of anatomical features in this study.

Objective—To compare navicular bone marrow lesion (BML) conspicuity in the feet of horses as determined via 2 fat-suppressed MRI techniques, including standard short tau inversion recovery (STIR) and inversion recovery gradient echo (IRGE). Sample—Feet (n = 150) of horses with lameness referable to the distal portion of the digit. Procedures—STIR and IRGE sequences were obtained prospectively in all feet with a standing low-field equine MRI system. Presence of a BML was ascertained by identification of a characteristic combination of marrow alterations in T1-weighted, T2*-weighted, T2-weighted, and STIR images. Signal-to-noise and contrast-to-noise ratios were calculated on STIR and IRGE sequences in 56 feet with a navicular BML. Results—Signal-to-noise and contrast-to-noise ratios of both sequences correlated linearly (r = 0.87 and r = 0.92, respectively) but were significantly higher for STIR images (mean ± SD, 22.6 ± 12.7 and 12.4 ± 11.4, respectively), compared with IRGE images (13.7 ± 8.0 and 5.9 ± 7.2, respectively). Conclusions and Clinical Relevance—Results suggested that the IRGE sequence revealed BMLs significantly less conspicuously, compared with the standard STIR sequence. The 2 techniques cannot be used interchangeably, and IRGE is therefore not recommended as the sole fat-suppressed sequence for routine equine standing MRI protocols.

The main aim of the study was to compare the shape of navicular bones classified as normal and pathologically changed. A comparison of metric features of the navicular bone between different types of horses and associating the examined parameters to the size of the middle and distal phalanges was an additional aspect of the study. The material comprised 53 horses of various breeds which were divided into three types. Through anatomical examinations it was concluded that as many as 30 navicular bones were normal, while 23 were found to present pathological changes. The following methods of statistical analysis were used: Levene's test, one-way ANOVA, T-test, LSD test and Pearson correlation. The shape of the navicular bone was described by seven indices developed for this purpose. From among them, three show statistically higher values in the affected bones compared to the healthy ones. The main result of the study is that navicular bones with defects are relatively thicker and have a higher flexor surface and a higher articular surface for the joint with the middle phalanx. Therefore our hypothesis is that the occurrence of pathological changes of the navicular bone is preceded by an increase in the thickness and height of this bone. Adverse changes occur only in the subsequent stage of the process. The study also revealed the interrelations between the phalanges and some metric features of the navicular bone. There were strong correlations between the breadth of the middle and distal phalanx, and the breadth and thickness of the navicular bone. Also, the height of the flexor surface of the navicular bone is strongly correlated with the breadth of the phalanges.

Invasive pneumococcal disease predominantly affects younger children, elderly, and immunocompromised patients. Pneumococcal meningitis is a particularly important form of presentation, considering its high rate of morbimortality. We present the case of a previously healthy 12-year-old adolescent male who was hospitalized due to suspicion of osteoarticular infection in his left foot. A few hours later, he developed meningeal signs, exhibiting slight pleocytosis andStreptococcus pneumoniaeisolates in both cerebrospinal fluid and blood. Imaging studies were inconclusive regarding the nature of the foot disorder. We considered the hypothesis of osteomyelitis of the navicular bone as the most likely, for which he completed six weeks of antibiotic therapy. There was a favorable clinical evolution, along with complete absence of osteoarticular or neurological sequelae. The relevance of this clinical case resides in the unusual presentation of invasive pneumococcal disease in this age group, as well as in the rare form of orthopedic involvement.

This study describes a radiographic survey of the anatomical development of the distal extremity of the manus in the donkey from 0 to 2 years of age. The right distal limb of 10 donkey foals, born in the spring of 2012, underwent radiographs every month for the first 6 months of age and every 3 months during the following 18 months. Latero-medial radiographs with and without barium marker at the coronary band and dorso-palmar radiographs with both front feet in weight bearing were obtained. The distal physis of the third metacarpal bone and the proximal physis of the proximal phalanx (phalanx proximalis) were closed at the mean age of 18.6 months. The distal physis of the proximal phalanx appeared as a clear radiolucent line at 2 weeks of age and was still subtly visible in some donkeys at 24 months. The proximal physis of the middle phalanx (phalanx media) was closed at the mean age of 16.7 months. The distal physis of this phalanx was visible at birth, but closed at 4 days. The distal phalanx (phalanx distalis) was triangular at birth. At the age of 20-21 months, the palmar processes (processus palmares) were both developed. The navicular bone (os sesamoideum distalis) was developed at the mean age of 9 months. The proximal sesamoid bones (ossa sesamoidea proximalia) were seen in continuously development during the 24 months. It seems that the physes in the distal extremity of the manus in the donkey close at an older age than the physes in the horse.

CVT is a rare, severe, important deformity. This case report is to highlight the importance of deformity and early notification. Surgical correction as one stage procedure is probably the best procedure. CVT has no sex prevalence, bilateral in 50% of cases and more than 50% of cases a secondary cause implicated. Pathological anatomy involves dislocation of the talonavicular articulation with the oscalcis. Navicular bone is displaced onto the dorsolateral aspect of the talar head. Diagnostic criteria for CVT were persistent talonavicular dislocation on forced plantar flexion of foot. Talus axis and metatarsal base axis angles (TAMBA) and Calcaneal Axis and metatarsal axis (CAMBA) are introduced. TAMBA and CAMBA enable us to describe the obliquity of the talus and calcaneus, also the severity of the dislocation of the talonavicular joint and the contracture of the tendo Achilli. The current treatment is a one-stage open reduction of the talonavicular dislocation, combined with a posterior release. A subtalar bone block is often imperative to maintain correction. The surgery for (CVT) can lead complications.

Reasons for performing study: Osseous resorption of the flexor surface of the distal phalanx of the horse has been identified previously using magnetic resonance (MR) imaging; however, little is known about the prevalence and characteristics of this lesion. Objectives: To establish the MR prevalence of resorptive lesions in the flexor surface of the distal phalanx and identify concurrent lesions associated with this finding and associations between the MR and radiographic findings. Methods: Horses with distal extremity MR and radiographs performed within 2 weeks of each other were included in the study. The flexor surface of the distal phalanx was graded independently on both modalities for the presence of osseous resorption. The sensitivity and specificity of radiography for identifying osseous resorption was calculated using MR as the gold standard. Results: Eighty-two MR studies met the inclusion criteria, 8 of which included osseous resorption of the flexor surface of the distal phalanx. Concurrent injury to the deep digital flexor tendon and the navicular bone was a common finding. An association between MR and radiographic grades was identified. Radiography had a high specificity (0.96) but lower sensitivity (0.45-0.55) for detecting osseous resorption. Conclusions: Osseous resorption of the flexor surface of the distal phalanx can be observed both on MR and radiographic examinations of horses with lameness localised to the foot. This lesion is most often associated with other pathological changes in the podotrochlear apparatus. Potential relevance: Focal radiolucency of the flexor surface of the distal phalanx is a newly recognised radiographic sign associated with pathological changes of the podotrochlear apparatus.

Summary Reasons for performing study The distribution of lesions detected using magnetic resonance imaging (MRI) of hind feet has not been reported. Objective To evaluate type and distribution of lesions detected using MRI in hind feet of lame horses and to compare the findings with those reported in front feet; to document follow-up information. Methods Horses were selected if hindlimb lameness was abolished by plantar nerve blocks performed at the base of the proximal sesamoid bones. Magnetic resonance images were acquired using either a low-field or a high-field magnet, and all images were evaluated retrospectively by both authors. A primary diagnosis was defined as the most likely cause of lameness, based also on clinical findings and results of other imaging techniques. If ≥3 structures were equally affected, the horse was classified as having multiple injuries. Follow-up information was collected by telephone questionnaire; outcome was classified as return to former level of athletic function, working at a lower level or retired. Results Thirty-eight horses were included. Primary collateral sesamoidean ligament (CSL) injury was identified in 9 horses. Nine horses had multiple injuries, 8 had primary bone pathology, 5 had collateral desmopathy of the distal interphalangeal joint, one had primary deep digital flexor tendonitis, 2 had navicular bone pathology and 4 had lesions involving other structures within the foot. Seven horses were subjected to euthanasia shortly after diagnosis; 6 as a result of poor prognosis and one as a result of post anaesthetic complications, 4 of which had primary bone lesions, 2 multiple lesions and one distal interphalangeal joint pathology. Follow-up information was available for 24 horses. Eleven horses returned to previous performance and 2 to a lower level of performance; 9 horses were retired because of recurrent lameness. Five of 8 horses with CSL injury returned to previous performance and 2 to a lower level. Conclusions and potential relevance Collateral sesamoidean ligament injury and primary bone pathology are commonly observed on MRI examination of hind feet, and the prognosis is reasonable.

Osteochondritis dissecans most often affects the convex articular surfaces of the knee, the elbow, and the ankle joints; other sites of manifestation are very rare. Here we report a case of osteochondritis dissecans of the talonavicular joint affecting the concave part of the tarsal navicular bone in a 22-year-old woman, which was successfully treated by surgery, leading to complete recovery. Early diagnosis and surgery in stages of undamaged cartilage may help to prevent disease progression and the development of disabling osteoarthritis in the physiologically heavily loaded talo-navicular joint. (J Am Podiatr Med Assoc 102(4): 338-342, 2012)

Summary Reasons for performing study: There is limited knowledge about both histological features in early navicular disease and what histological features are represented by increased signal intensity in fat-suppressed magnetic resonance (MR) images of the navicular bone. Objective: To characterise increased signal intensity in the spongiosa of the navicular bone in fat-suppressed MR images and to compare this with histopathology; and to compare objective grading of all aspects of the navicular bone on MR images with histological findings. Methods: One or both front feet of 22 horses with foot pain and a median lameness duration of 3 months were examined using high-field MR imaging (MRI) and histopathology. The dorsal, palmar, proximal and distal borders of the navicular bone and the spongiosa were assigned an MRI grade (0–3) and a histological grade and compared statistically. Results: Increased signal intensity in the spongiosa of the navicular bone was associated with a variety of abnormalities, including fat atrophy, with lipocytes showing loss of definition of cytoplasmic borders, a proliferation of capillaries within the altered marrow fat, perivascular or interstitial oedema, enlarged intertrabecular bone spaces, fibroplasia and thinned trabeculae showing loss of bone with irregularly spiculated edges of moth-eaten appearance. There were significant associations among histological lesions of the fibrocartilage, calcified cartilage and subchondral bone. There were also significant associations between MRI grading of the spongiosa and both histological marrow fat grade and the combined maximum of the MRI grades for the fibrocartilage. Conclusions and potential relevance: Increased signal intensity in the spongiosa of the navicular bone in fat-suppressed MR images may occur in association with lesions of the fibrocartilage with or without subchondral bone or may represent a separate disease entity, particularly if diffuse, reflecting a variety of alterations of trabecular bone and marrow fat architecture.

Reasons for performing study: Distal border synovial invaginations of the distal sesamoid bone are radiographically assessed during the selection process of horses admitted as breeding stallions or in purchase examinations. Nowadays, many moderately or some deeply penetrating proximally enlarged synovial invaginations are considered as moderate or severe radiographic findings. Objective: To measure the difference between and agreement of the morphology of distal border synovial invaginations on radiography vs. computed tomography (CT). It was hypothesised that the morphology of distal border synovial invaginations would be better evaluable on CT compared with radiography. Methods: Computed tomography scans and 3 dorsoproximal-palmarodistal oblique (DPr-PaDiO) radiographs were obtained on 50 cadaver forefeet from 25 Warmblood horses. Computed tomography was assumed to be the gold standard. The number, shape and depth of penetration of distal border synovial invaginations into the distal sesamoid bone were evaluated with both methods, and the comparison of their measurements was statistically described. Results: A statistically significant mean difference for number of distal synovial invaginations between CT and all 3 DPr-PaDiO projections was found and was approximately equal to 2, meaning that CT permits visualisation of an average of 2 more invaginations than radiography. In none of the cases did radiography have a higher number observed than CT. A large variation in the difference of measurements for depth of penetration against their mean difference between CT and the 3 radiographic projections was seen. Radiography underestimated the depth of invaginations, and more so when these were deeper. There was no statistically significant mean difference found between the techniques for depth. A moderate to good agreement between measurements on CT and the three DPr-PaDiO projections for shape was seen, in which the D55°Pr-PaDiO projection showed the best agreement. A high specificity (90-99%) and low sensitivity (65%) for all projections for shape were found. Conclusions and potential relevance: Radiography differs considerably from CT concerning the morphology of distal navicular border synovial invaginations. For the evaluation of the number, depth and shape of distal synovial invaginations in the distal sesamoid bone, radiography shows only partially the morphology seen on CT.

Navicular stress injuries in athletes can be devastating. Clinical findings are frequently nonspecific until significant progression of the abnormality has occurred. The use of diagnostic imaging techniques early in the discovery period increases the likelihood of establishing an immediate diagnosis and avoids frank fracture of the navicular bone. Delayed diagnosis of navicular stress injuries in athletes can cause dire consequences. The physician must be aware of the injury in establishing a high index of clinical suspicion. The timing and sequencing of diagnostic imaging studies is essential in establishing a diagnosis to manage the patient and minimize time away from competition. This case study examines the history and management of an elite high school track athlete who sustained a navicular stress injury. The timing and use of diagnostic imaging studies is reviewed. (J Am Podiatr Med Assoc 101(5): 447–451, 2011)

Summary Reasons for performing study: Diagnostic navicular bursoscopy has been described in limited cases. Review of greater numbers is needed to define its contribution to case management and prognostic values. Objectives: To report: 1) clinical, diagnostic and endoscopic findings in a series of cases, 2) surgical techniques and case outcomes and 3) prognostic values. The authors hypothesise: 1) lameness localising to the navicular bursa is commonly associated with dorsal border deep digital flexor tendon (DDFT) lesions, 2) endoscopy allows extent of injuries to be assessed and treated, 3) case outcome relates to severity of DDFT injury and 4) the technique is safe and associated with little morbidity. Materials and methods: All horses that underwent endoscopy of a forelimb navicular bursa for investigation of lameness were identified. Case files were reviewed and those with injuries within the bursa selected for further analysis. Results: One-hundred-and-fourteen horses were identified. Ninety-two had injuries within the bursa and DDFT injuries were identified in 98% of bursae. Of those examined with magnetic resonance imaging (MRI), 56% had combination injuries involving the DDFT and navicular bone. Sixty-one percent of horses returned to work sound, 42% returned to previous performance. Horses with extensive tearing and combination injuries of the DDFT and navicular bone identified with MRI, had worse outcomes. Conclusions: Lameness localising to the navicular bursa is commonly associated with injuries to the dorsal border of the DDFT. Endoscopy permits identification and characterisation of injuries within the navicular bursa and enables lesion management. Outcome following debridement is related to severity of injury but overall is reasonable. Potential relevance: Horses with lameness localising to the navicular bursa may have tears of the DDFT. Bursoscopy is able to contribute diagnostic and prognostic information and debridement of lesions improves outcome compared to cases managed conservatively.

Summary Reasons for performing study: The significance of distal border fragments of the navicular bone is not well understood. There are also no objective data about changes in thickness and proximal/distal extension of the palmar cortex of the navicular bone. Objectives: To describe the distribution of distal border fragments and their association with other radiological abnormalities of the navicular bone and describe the shape of the navicular bone in sound horses and horses with foot-related lameness, including navicular pathology. Methods: Sound horses had radiographs acquired as part of a prepurchase examination. Lame horses had forelimb lameness abolished by palmar nerve blocks performed at the base of the proximal sesamoid bones. Diagnosis was assigned prospectively based on results of local analgesia and all imaging findings. The thickness of the palmar cortex of the navicular bone and size of proximal/distal extensions were measured objectively. Other radiological abnormalities were evaluated subjectively and each navicular bone graded. Results: Fifty-five sound and 377 lame horses were included. All measurements were larger in lame compared with sound horses except the size of the distal extension of the palmar cortex. Fragments were observed in 3.6 and 8.7% of sound and lame horses respectively and in 24.1% of horses with a diagnosis of primary navicular pathology. There was an association between fragments and overall navicular bone grade, radiolucent areas at the angles of the distal border of the navicular bone and number and size of the synovial invaginations. Conclusions and potential relevance: The palmar cortex of the navicular bone was thicker in lame compared with sound horses. Distal border fragments were most frequent in horses with navicular pathology. Evaluation of changes in shape of the navicular bone may also be important for recognition of pathological abnormalities of the bone.

Summary Reasons for performing study: To date, few reports exist comparing magnetic resonance imaging (MRI) and computed tomography (CT) for imaging of the equine distal limb, yet clinicians are required to decide which modality to use regularly. Objectives: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot. Hypothesis: Anatomic visualisation score discrepancies would exist between CT, CECT and LFMRI. Methods: Images of 22 lame horses (31 limbs) undergoing both CT and LFMRI of the foot were reviewed. When available, CECT images were reviewed. The deep digital flexor tendon (DDFT) was categorised into proximal to distal levels (A–D), structures were assigned visualisation scores (Grades 0–3) and technique comparisons were made using the paired marginal homogeneity test. Results: Computed tomography and LFMRI had similar visibility scores for the navicular bone, middle phalanx, DDFT-B, collateral ligaments of the distal interphalangeal joint and collateral sesamoidean ligament of the navicular bone. The proximal and distal phalanx had lower visibility scores with LFMRI. The distal DDFT (C–D), distal sesamoidean impar ligament and synovial structures had higher scores with LFMRI. Contrast enhanced CT lowered DDFT and collateral sesamoidean ligament scores and raised distal interphalangeal synovium CT visualisation scores. Conclusions and potential relevance: Visualisation scores differ depending on imaging technique and anatomic structure of interest. This information increases our understanding of the limitations of CT, CECT and LFMRI to visualise anatomy in clinical cases.

Navicular disease is characterized by a progressive degenerative alteration of the equine podotrochlea. In this study, we refined a previously identified quantitative trait locus (QTL) on horse chromosome 10 for the abnormal development of canales sesamoidales (DCS) of the navicular bone in Hanoverian warmblood horses. Genotyping was done in 192 Hanoverian warmblood horses from 17 paternal half-sib groups. The whole marker set comprised 45 markers including seven newly developed microsatellites and 13 single nucleotide polymorphisms (SNPs) within positional candidate genes. Chromosome-wide significant QTL were confirmed and refined for DCS on horse chromosome (ECA) 10 at 0.16-2.70 Mb and at 14.45-36.37 Mb. Nine microsatellites and three SNP markers reached the highest multipoint Zmeans and LOD scores at 19.34-20.38 Mb and at 23.17-30.73 Mb with genome-wide error probabilities of P

Summary Reasons for performing study: Currently, there are limited data regarding the long-term outcome of horses with foot pain treated with corrective shoeing, rest and rehabilitation, and intrasynovial anti-inflammatory medication to target lesions detected with MRI. Objective: To report the long-term (≥12 months) outcome of horses with foot lesions following medical therapy. Hypotheses: 1) There is no association between clinical parameters considered and a poor response to therapy. 2) Horses with a deep digital flexor tendinopathy are less likely to respond to medical therapy than horses without a deep digital flexor tendinopathy. Methods: The medical records of horses with foot pain subjected to MRI examination and medical therapy (2005–2007) were evaluated retrospectively. Data collected included history, signalment, occupation, duration and severity of lameness at the time of MRI, radiological and MRI abnormalities. Number of treatments, complications and long-term response to treatment were obtained by detailed telephone questionnaires. Association between clinical and MRI findings and long-term lameness were investigated. Results: Frequent abnormal structures included the navicular bone, the deep digital flexor tendon, the navicular bursa and the distal interphalangeal joint. Thirty-four of 56 horses (60.7%) failed to return to previous level of exercise due to persistent or recurrent lameness or owners' decision to decrease the horse's athletic level; however, 11 horses (32.3%) were being used for light riding. Prognosis for horses with concurrent deep digital flexor tendon, navicular bone and navicular bursa lesions was worse than horses with individual lesions. Deep digital flexor tendinopathy was strongly associated with persistent or recurrent lameness. Conclusions: Horses with multiple foot lesions managed with conservative therapy have a guarded prognosis for long-term soundness. Deep digital flexor tendinopathies negatively influence prognosis.

Summary Reasons for performing study: Distal border fragments of the navicular bone can be seen in lame and nonlame horses and their clinical significance remains open to debate. Objectives: To describe the magnetic resonance imaging (MRI) appearance of distal border fragments and the adjacent navicular bone. To investigate the relationship between fragments and other abnormalities of the navicular bone and the distal sesamoidean impar ligament (DSIL). Methods: Horses were included if pain causing forelimb lameness was localised to the foot and high-field MR images were acquired. The size and location of distal border fragments were recorded. Abnormalities in the adjacent navicular bone were graded to obtain a fragment grade. A total navicular bone grade was assigned. The DSIL was also graded. A Chi-squared test was used to test for associations between the presence of a fragment and specific lesions involving the distal border of the navicular bone, the total grade of the navicular bone, and the grade of the DSIL. Results: 427 horses were included and 111 fragments observed. There was a significant association between the presence of a fragment and the total navicular bone grade, osseous cyst-like lesions, increased number and size of the synovial invaginations of the distal border, increased signal intensity on fat suppressed images and size of distal border entheseophytes. Conclusions: There is an association between distal border fragments and other pathological MRI abnormalities of the navicular bone. Potential relevance: Distal border fragments are part of navicular disease, but their contribution to pain and lameness remains to be clarified.

Summary Reasons for performing study: There is limited knowledge about the interpretation of alterations in the distal sesamoidean impar ligament (DSIL) detected using magnetic resonance imaging (MRI) and their correlation with histopathology. Hypotheses: There would be: 1) a correlation between histopathology and MRI findings; and 2) a relationship between MR abnormalities at the origin and the insertion of the DSIL, between insertion and body; and origin and body. Methods: Fifty limbs from 28 horses were examined using high-field MRI and histopathology. MR abnormalities of the DSIL, its origin on the navicular bone and its insertion on the distal phalanx were graded. Sections of the axial third of the DSIL were examined histologically and graded according to fibre orientation, integrity of fibroblasts, collagen architecture and vascularity. Associations between MRI and histology findings were tested by Spearman rank correlation and Chi-squared tests. Results: There were significant correlations between the presence of a cystic structure in the distal third of the navicular bone, or a distal border fragment, or increased signal intensity in fat suppressed images at the insertion of the DSIL on the distal phalanx and the histological grade of the body of the DSIL. There were significant associations between a cystic structure in the distal third of the navicular bone and the presence of either a distal border fragment or entheseous new bone at the insertion of the DSIL, swelling of the DSIL and increased signal intensity in the DSIL in fat suppressed images; between distal elongation of the flexor border of the navicular bone and the presence of one or more distal border fragments and between swelling of the body of the DSIL and irregularity of its palmar border or increased signal intensity in fat suppressed images in the DSIL. Conclusions and clinical relevance: The presence of a cystic structure in the distal third of the navicular bone detected using MRI, a distal border fragment or increased signal intensity at the insertion of the DSIL are suggestive of significant alterations in the infrastructure of the DSIL.

Summary Reasons for performing study: Causes of palmar foot pain and the aetiopathogenesis of navicular disease remain poorly understood, despite the high incidence of foot-related lameness. Hypotheses: Abnormalities of the deep digital flexor tendon (DDFT) may contribute to palmar foot pain; ageing degenerative changes may be seen in horses free from lameness; and horses with lameness are likely to have a greater severity of abnormalities than age-matched horses with no history of foot pain. Methods: Feet were selected from horses with a history of uni- or bilateral forelimb lameness of at least 2 months' duration. Histology of the DDFT from the level of the proximal interphalangeal joint to its insertion were examined and the severity of lesions for each site graded. Associations between lesions of the navicular bone, collateral sesamoidean ligaments (CSL), distal sesamoidean impar ligament, navicular bursa, distal interphalangeal (DIP) joint synovium and collateral ligaments of the DIP joint and DDFT were assessed. Results: There was no relationship between age and grade of histological abnormality of the DDFT. There were significant histological differences between groups for lesions of the dorsal layers of the DDFT, but not for lesions of the palmar aspect. There were significant associations between histological grades for the superficial dorsal layer of the DDFT and flexor aspect of the navicular bone; and between the deep dorsal layer of the DDFT and the proximal border and medulla of the navicular bone. The navicular bursa grade was correlated with grades for the superficial dorsal, deep dorsal and deep palmar layers of the DDFT. The histological grades for the CSL and the superficial dorsal layer of the DDFT were also associated. Conclusions: Pathological abnormalities in lame horses often involved the DDFT in addition to the navicular bone. Vascular and matrix changes may precede changes in the fibrocartilage of the navicular bone. Potential relevance: Identification of factors leading to vascular changes within the interstitium of the DDFT and changes in matrix composition, may help in future management of palmar foot pain.

The purpose of the present study was to evaluate the nature of ossification of the cartilages in the front feet of young, about 2-year-old Norwegian coldblooded horses, and to compare offspring of different sires in this respect. Dorsopalmar radiographs of the front feet of 392 horses (187 female and 205 male) were evaluated for ossification at the base of the cartilage and for separate centres of ossification. The horses were offspring of 45 different sires. Ossification extending above the navicular bone and separate centres of ossification were considered as significant. Minimal to mild ossification at the base of the cartilages was commonly seen, and significant ossification was present in one or more of the cartilages in 11.5% of the horses. The lateral compared to medial cartilages had more ossification and females had more ossification and more separate centres of ossification than males. The prevalence of horses with significant ossifications was significantly higher (46.3%) among offspring of one frequently used stallion than in the group consisting of offspring of 4 other popular stallions (3.5%) and in another group consisting of offspring of other, less frequently used stallions (9.6%). Ossification of the cartilages is considered to have a hereditary background in Norwegian coldblooded horses.

Summary Reasons for performing study: Previous studies have implicated tension in the deep digital flexor tendon (DDFT) in the rotation of the distal phalanx (DP) after the breakdown of the dorsal laminae caused by laminitis. Howeveer, once the DP has rotated, the DDFT should become shorter, reducing the force it exerts on the DP. Objective: To compare DDFT force and ground reaction forces (GRFs) in normal ponies and ponies with rotation of the DP as a sequel to laminitis. Methods: Six normal ponies (Group 1) and 6 sound ponies with 6-13° of rotation of the DP in relation to the dorsal hoof wall (Group 2) were assessed at trot using forceplate and motion analysis. The force in the DDFT was calculated by assuming that the extending moment at the distal interphalangeal (DIP) joint resulting from the GRF was equal to the flexing moment created by the force in the DDFT during the stance phase (inverse dynamics). Results: In early stance, the peak DDFT force (mean ± s.d.) in the normal ponies was 1.92 ± 1.63 N/kg. However, in Group 2, the point of zero moment was palmar to the centre of rotation of the DIP joint for the first 40% of stance and hence DDFT force was zero. Force in the DDFT reached a peak of 10.00 ± 3.56 N/kg at 60.7 ± 5.6% of stance in Group 1 and 6.41 ± 1.37 N/kg at 79.2 ± 9.6% of stance in Group 2. Conclusions: DDFT force in Group 2 laminitic ponies was much reduced until late stance, when it neared normal values. Potential relevance: Further studies of ponies with rotation of the DP as a sequel to laminitis should assist farriery aimed at reducing the force in the DDFT through the breakover phase of stance to protect damaged dorsal laminae.

Summary Reasons for performing study: Collapsed heels conformation has been implicated as causing radical biomechanical alterations, predisposing horses to navicular disease. However, the correlation between hoof conformation and the forces exerted on the navicular bone has not been documented. Hypothesis: The angle of the distal phalanx in relation to the ground is correlated to the degree of heel collapse and foot conformation is correlated to the compressive force exerted by the deep digital flexor tendon on the navicular bone. Methods: Thirty-one shod Irish Draught-cross type horses in routine work and farriery care were trotted over a forceplate, with 3-dimensional (3D) motion analysis system. A lateromedial radiograph of the right fore foot was obtained for each horse, and various measurements taken. Correlation coefficients were determined between hoof conformation measurements and between each of these and the force parameters at the beginning (15%) of stance phase, the middle of stance (50%) and at the beginning of breakover (86% of stance phase). Significance was defined as P

Summary Horses with navicular disease have an increased load on the navicular bone in early stance. This has been suggested to be a response to pain in the heel region. Seven horses with clinical, radiographic and scintigraphic signs of navicular disease underwent forceplate and kinematic analysis before and after desensitisation of the heel region with a bilateral palmar digital nerve block. The compressive force exerted on the navicular bone during stance, and stride kinematics, were determined in each state. After regional analgesia of the palmar digital nerves (PDNB) the compressive force on the navicular bone was lower throughout stance. The mean ± s.d. peak force at the beginning of stance was 7.05 ± 1.10 N/kg before, and 6.46 ± 1.15 N/kg after PDNB (P = 0.01) and at the end of stance the mean peak values were 5.00 ± 2.05 N/kg before, and 4.39 ± 1.65 N/kg after PDNB (P = 0.05). We explained this finding as indicating that the horse responds to heel pain (including pain in the navicular region) by contracting the deep digital flexor muscle to unload the heels. This increases the compressive load on the navicular bone, which may cause remodelling and, in some horses, damage to the overlying flexor cartilage, which is then painful and identified as navicular disease. This mechanism identifies navicular disease as a possible end point for a variety of heel related conditions.

Summary Numerous different techniques for injection of the navicular bursa have been described but there is little conformity between these descriptions. A literature review was performed and techniques for injection of the navicular bursa were categorised into 5 approaches. This study was performed to evaluate the reproducibility of each technique and to assess which technique was consistently most successful. Five inexperienced operators performed each technique on 5 cadaver forelimbs. Once a needle had been placed, a radiograph was taken to confirm placement was in accordance with the description of the technique. Contrast agent was then injected and another radiograph taken to determine whether the navicular bursa had been injected successfully. The position of the navicular bone was highly predictable as a point 1 cm distal to the coronary band and halfway between the most dorsal and most palmar aspect of the coronary band. The use of this point as a landmark for injection of the navicular bursa allowed a high degree of accuracy and reliability of needle placement, irrespective of foot conformation.

Summary Reasons for performing study: Foot pain is a common cause of equine lameness and there have been significant limitations of the methods available for the diagnosis of the causes of foot pain (radiography, nuclear scintigraphy and ultrasonography). Until recently, magnetic resonance imaging (MRI) in the horse has been limited to examination of cadaver limbs. Objectives: Our purpose was to 1) describe MRI of the foot in live horses, 2) describe MRI findings in horses with foot pain in which a definitive diagnosis could not be established by alternative means and 3) correlate MRI findings with other methods of clinical investigation. Methods: The feet of 15 horses with unilateral (12) orbilateral (3), forelimb (14) or hindlimb (1) lameness associated with foot pain of previously ill-defined origin were examined using MRI. The horses were examined in right lateral recumbency under general anaesthesia, with the feet positioned in the isocentre of a flared end 1.5 Tesla GE Signa Echospeed magnet. Images were obtained in sagittal, transverse and dorsal planes using 3-dimensional (3D) T2* gradient echo (GRE), spoiled gradient echo, fat-saturated 3D T2* GRE and short inversion recovery sequences. Image acquisition took approximately 1 h. Results: Abnormalities of the distal interphalangeal joint (DIP) cartilage and /or subchondral bone, periarticular osteophyte formation, distension of the DIP joint capsule with or without synovial proliferation, distension of the navicular bursa with or without evidence of chronic inflammation, surface and core lesions in the deep digital flexor tendon, abnormal signal within the navicular bone, evidence of mineralised fragments in the distal sesamoidean impar ligament, irregular outline of and signal in the medial cortex of the distal phalanx, and an abnormal signal on the dorsal aspect of the distal phalanx consistent with laminitis were identified. Conclusions: MRI permits the diagnosis of a variety of lesions involving different structures within the foot that cannot be diagnosed using other means, thus enhancing our knowledge of the causes of foot pain. Potential relevance: With further experience it is likely that lesions involving other structures will also be identified. Long-term follow-up data is required to determine the prognosis for the injuries described.

Reasons for performing study: Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra- and interobserver agreement have not been established. Objective: To determine intra- and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT. Methods: Radiographs and CT scans of 60 cadaver navicular bones were evaluated by 3 observers using published criteria. A subset of 30 studies was evaluated twice by one observer. Agreement was tested using the kappa statistic. Certainty about pathological changes was evaluated by giving the observers the option to choose 'not sure'. Results: Agreement varied from poor to almost perfect for radiographic evaluation and from poor to substantial for CT evaluation. For radiographic evaluation mean interobserver agreement was fair, as it was for CT evaluation. For radiographic evaluation mean intraobserver agreement was moderate as it was for CT evaluation. Pathological changes were evaluated with greater certainty on CT scans compared to radiographs; however, this was not associated with improved agreement. Conclusions: Variations in classification of navicular lesions in radiographic and CT studies were considerable between and within observers and challenge the use of such studies for diagnostic and prognostic purposes. Potential relevance: The results of this study allowed the identification of evaluation criteria with sufficient precision to be useful for navicular bone evaluation.