Topic:Distal Phalanx
The distal phalanx, also known as the coffin bone, is the innermost bone located within the hoof of a horse. It is a critical component of the equine skeletal system, providing structural support and playing a significant role in weight-bearing and locomotion. The distal phalanx is encased within the hoof capsule and interacts with various soft tissue structures, including the laminae, which connect the hoof wall to the bone. Conditions affecting the distal phalanx, such as fractures, infections, or laminitis, can have significant implications for a horse's mobility and overall health. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, biomechanics, pathology, and treatment options related to the distal phalanx in horses.
Comparisons of computed tomography, contrast enhanced computed tomography and standing low-field magnetic resonance imaging in horses with lameness localised to the foot. Part 1: anatomic visualisation scores. 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. Objective: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot. Objective: 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 ...
Fractures of the distal phalanx and associated soft tissue and osseous abnormalities in 22 horses with ossified sclerotic ungual cartilages diagnosed with magnetic resonance imaging. Ungual cartilage ossification in the forelimb is a common finding in horses. Subtle abnormalities associated with the ungual cartilages can be difficult to identify on radiographs. Magnetic resonance (MR) imaging findings of 22 horses (23 forelimbs) with a fracture of the distal phalanx and ossified ungual cartilage were characterized and graded. All horses had a forelimb fracture. Eleven involved a left forelimb (seven medial; four lateral), and 12 involved a right forelimb (five medial; seven lateral). All fractures were nonarticular, simple in configuration, and nondisplaced. The fractures ...
An investigation of the relationships between angles and shapes of the hoof capsule and the distal phalanx. There is little scientific evidence to support the premise that poor foot conformation predisposes to foot pain and lameness. Objective: To determine relationships between external characteristics of the hoof capsule and angles of the distal phalanx; to determine variability in shape of the distal phalanx; and to investigate association between distal phalanx angles and the injury causing lameness. Methods: Feet were documented photographically and radiographically. Linear and angle measurements were obtained for the hoof capsule and distal phalanx and compared statistically. Horses were categ...
The effect of hoof angle variations on dorsal lamellar load in the equine hoof. In the treatment of laminitis it is believed that reducing tension in the deep digital flexor tendon by raising the palmar angle of the hoof can reduce the load on the dorsal lamellae, allowing them to heal or prevent further damage. Objective: To determine the effect of alterations in hoof angle on the load in the dorsal laminar junction. Methods: Biomechanical finite element models of equine hooves were created with palmar angles of the distal phalanx varying from 0-15°. Tissue material relations accounting for anisotropy and the effect of moisture were used. Loading conditions simulating t...
Is there an association between ossification of the cartilages of the foot and collateral desmopathy of the distal interphalangeal joint or distal phalanx injury? Associations between degree of ossification of the cartilages of the foot and injuries to other structures of the foot have been suggested, but have not been investigated by large scale studies. Objective: To describe the frequency of grade >3 ossification of the cartilages of the foot (possibly significant ossification, PSO), mediolateral symmetry of ossification and left-right symmetry between feet; and to investigate associations between PSO and injury of either the collateral ligaments (CLs) of the distal interphalangeal (DIP) joint or the distal phalanx. Objective: Possibly significant os...
Maggot debridement therapy for laminitis. Maggot debridement therapy is a nontraumatic, minimally invasive method to treat infections in a foot compromised by chronic laminitis. A mechanical strategy must first be in place to address the instability of the distal phalanx and hoof capsule. Adverse reactions to maggot debridement therapy are uncommon and the only side effect observed has been irritation or hypersensitivity at the site. Chronic laminitic cases of sepsis/necrosis within the hoof benefit from this procedure due to the noninvasive, continuous debridement and healing properties provided by the larvae.
Farriery for chronic laminitis. Laminitis is considered chronic once the distal phalanx has displaced within the hoof capsule. Chronic laminitis generally occurs as a direct sequel to acute laminitis. Clinical evaluation of chronic laminitis is best performed with a thorough clinical examination and radiography. The mainstay of hoof care is therapeutic farriery. In this article, the goals and principles of hoof care, the appropriate trim and various shoes that form the bulk of farriery for chronic laminitis, and surgical treatments are discussed.
Chronic laminitis: foot management. Laminitis is a disease of the suspensory apparatus of the distal phalanx, which can advance to the chronic stage with varying degrees of structural failure. Because the disease may ultimately lead to mechanical failure of the digit, a foot management plan is required to effectively and mechanically treat these cases. Many laminitis cases can be successfully rehabilitated back to athletic soundness, light use, breeding, or pasture soundness, whereas others suffer from permanent instability and never enjoy an acceptable level of comfort. To understand how to minimize damage in the acute laminiti...
The distal sesamoidean impar ligament: comparison between its appearance on magnetic resonance imaging and histology of the axial third of the ligament. 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. Objective: 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 insert...
Osteomyelitis and osteonecrosis after intraosseous perfusion with gentamicin. To describe and discuss previously unreported complications associated with intraosseous perfusion with gentamicin in horses. Methods: Case report. Methods: Ten-year-old Warmblood gelding. Methods: Intraosseous perfusion with gentamicin into the proximal phalanx (P1) was used as part of the treatment regimen for distal interphalangeal joint and navicular bursa synovial sepsis. Although the sepsis responded favorably complications developed at the perfusion site, including persistent osteomyelitis, progressive osteonecrosis, and ultimately pathologic fracture of P1. Results: The progression of ...
Chronic laminitis: strategic hoof wall resection. In the chronic-laminitic foot, severe soft-tissue compression and compromised circulation can result in osteitis and sepsis at the margin of the distal phalanx. Resultant inflammation and sepsis may cause the coronary corium to swell, drain, or separate from the hoof capsule, usually within 8 weeks of laminitis onset. Slow-onset cases of soft-tissue impingement can develop secondary to distal phalanx displacement due to lack of wall attachment. With either presentation, partial upper wall resection is required to reverse compression and vascular impingement by the hoof capsule. If the patholog...
Pathology of the distal phalanx in equine laminitis: more than just skin deep. The etiopathogenesis of laminitis is complex and involves multiple tissue types. It may be initiated by biomechanical, traumatic, inflammatory, vascular, toxic, and metabolic factors. Although histopathologic changes occurring within the lamellae of experimental models of laminitis are well described and reported, histopathologic changes occurring in the distal phalanx are not, even though gross and radiographic evidence of disease are often apparent and bony lesions could be considered a significant source of pain. Recent scientific evidence indicates that the microenvironment of bone is an i...
Carbohydrate alimentary overload laminitis. In acute laminitis, the suspensory apparatus of the distal phalanx fails at the lamellar dermal/epidermal interface. A grading system for the histopathology of laminitis is based on the consistent pattern of histologic changes to the secondary epidermal lamellae, basal cells, and basement membrane that occur as carbohydrate-induced laminitis develops. The actual trigger factors of carbohydrate-induced laminitis remain unidentified.
Clinical presentation, diagnosis, and prognosis of chronic laminitis in North America. Chronic laminitis involves laminar morphologic changes resulting in digital collapse and can vary greatly in its clinical manifestation depending on duration, severity of lameness, and stability of the distal phalanx/hoof wall interface. Accurate assessment of the whole patient is mandatory and consideration must be given to signalment, occupation, and owner expectations, as well as history and etiology, which often predict the broad course of the disease. Diagnosis is made via physical examination with adjunctive serial radiographic evaluation and possibly venography. Eventual functionality o...
The anatomy and physiology of the suspensory apparatus of the distal phalanx. The equine hoof capsule protects the softer, more sensitive, structures within. Failure of the connection between hoof and bone (suspensory apparatus of the distal phalanx or SADP) results in the crippling lameness of laminitis. Active basal cell proliferation occurs principally in tubular hoof and proximal and distal lamellae. The remaining lamellae are virtually non-proliferative and the hoof wall moves past the stationary distal phalanx, by controlled activation and inhibition of constituent proteases. The lamellar corium derives most of its blood supply from the branches of the terminal ar...
Long-term outcome after arthroscopic debridement of distal phalanx extensor process fragmentation in 13 horses. To report long-term outcome after arthroscopic removal of fragmentation of the extensor process of the distal phalanx in horses. Methods: Case series. Methods: Adult horses (n=13). Methods: Medical records (2003-2004) of horses that had arthroscopic debridement of fragmentation of the extensor process of the distal phalanx were reviewed. Inclusion criteria included: lameness localized to the foot, fragmentation of the extensor process of the distal phalanx debrided arthroscopically, and a follow-up period of > or = 4 years. Results: Of the 13 horses, lameness was resolved in 11 (85%) initia...
Use of computed tomography in standing position to identify guidelines for screw insertion in the distal phalanx of horses: an ex vivo study. To compare the precision of radiography and computed tomography (CT) preoperatively in the standing position for identification of guidelines for screw insertion in the distal phalanx, and to identify whether standing CT might improve operative time compared with preoperative radiographic planning. Methods: Experimental ex vivo study. Methods: Cadaveric equine thoracic limb pairs (n=10). Methods: Insertion of a 4.5 mm cortex screw in lag fashion into an intact distal phalanx was evaluated in 2 groups (n=10) of cadaveric equine thoracic limbs. In 1 group, the site, direction, and length of the ...
The effect of focused extracorporeal shock wave therapy on collagen matrix and gene expression in normal tendons and ligaments. Extracorporeal shock wave therapy (ESWT) is frequently used in equine practice, but little is known about its biological action. Objective: To study the effects of ESWT on matrix structure and gene expression levels in normal, physiologically loaded tendinous structures in ponies. Methods: Six Shetland ponies, free of lameness and with ultrasonographically normal flexor and extensor tendons and suspensory ligaments (SL), were used. ESWT was applied at the origin of the suspensory ligament and the mid-metacarpal region of the superficial digital flexor tendon (SDFT) 6 weeks prior to sample taki...
Development of intraosseous infusion of the distal phalanx to access the foot lamellar circulation in the standing, conscious horse. Intraosseous (i.o.) infusion of the distal phalanx (IOIDP) as a delivery route targeting hoof lamellar tissue of standing, conscious horses was evaluated. Following sedation and regional nerve blockade in six Standardbred horses, a microdialysis (MD) probe was implanted into the hoof lamellar tissue of one forelimb. A purpose designed cannulated bone screw was introduced into the body of the distal phalanx, approximately 6 cm from the MD probe. Gentamicin solution (25 mg/mL) was infused at 20 microL/min through the bone screw for 2 h without the application of a tourniquet. MD and blood sample...
Multiple keratomas in an equine foot. A 19-year-old, Arabian gelding was presented for left hindlimb lameness and deviation of the hoof wall. Radiographs revealed a semicircular, radiolucent area in the lateral edge of the distal phalanx. Three distinct keratomas were successfully removed following hoof wall resection. Kératomes multiples sur le pied d’un cheval. Un cheval Arabe hongre âgé de 19 ans a été présenté pour une boiterie du membre postérieur gauche et une déviation de la paroi du sabot. La radiographie a révélé une région semi-circulaire radiotransparente au niveau du bord latéral de la phalange distale....
Radiographic, scintigraphic and magnetic resonance imaging findings in the palmar processes of the distal phalanx. Increased radiopharmaceutical uptake (IRU) in the palmar processes of the distal phalanx is recognised but its clinical significance has not been established. Objective: To investigate the relationship between radiographic, scintigraphic and MRI findings in the palmar processes of the distal phalanx. Objective: Increased radiopharmaceutical uptake in the palmar processes of the distal phalanx is associated with MRI abnormalities; IRU and MRI abnormalities are over-represented in lame limbs. Methods: Clinical data, radiographic, scintigraphic and MRI findings of 258 horses with unilateral or bi...
Septic osteitis of the distal phalanx in foals: 22 cases (1995-2002). To determine the clinical characteristics and outcome of foals with septic osteitis of the distal phalanx. Methods: Retrospective case series. Methods: 22 foals. Methods: Information obtained from medical records included signalment; clinical, laboratory, and radiographic findings; treatment method; and outcome. Foals included in the study had lameness referable to the foot, radiographic evidence of localized lysis or focal loss of bone density of the distal phalanx, and suppurative discharge or necrosis of the affected bone evident at surgery. Foals with a history or evidence of penetrating w...
Sonographic anatomy of the palmarodistal aspect of the equine digit. Although ultrasonography is widely used in equine orthopedics, its use in the distal portion of the digit is still limited. The purpose of this descriptive study was to document the normal ultrasonographic appearance of the palmarodistal aspect of the digital area imaged between the bulbs of the heels. Ultrasonographic images were obtained with a 7.5 MHz microconvex transducer in 10 fresh equine cadaver forelimbs and five soundhorses. Sagittal, parasagittal, and transverse images were obtained from the proximal aspect of the middle phalanx to the distal sesamoid bone. Anatomic sections were ob...
Sensitivity of an equine distal limb model to perturbations in tendon paths, origins and insertions. As equine musculoskeletal models become common, it is important to determine their sensitivity to the simplifications used. A subject-specific distal forelimb model was created using bones extracted from CT scans to examine movement from in-vivo invasive-marker motion capture. The movements of the sesamoid bones were simulated using the constraints of maintaining an isometric virtual ligament and maintaining contact between the appropriate articular surfaces, creating a variable moment arm for the tendons. The simulation of the proximal sesamoid bones was compared to movement recorded in-vitro...
Developmental aspects of distal limb conformation in the horse: the potential consequences of uneven feet in foals. Distal limb conformation is generally accepted to be an important item with respect to performance and soundness in mature horses, but little is known about the developmental aspects. Objective: To gain insight into the development of distal limb conformation and to assess the possible consequences of uneven feet in foals. Methods: Conformation of the distal front limbs of 23 Warmblood foals was scored visually and measured using radiographs, at ages 27 and 55 weeks. At the same ages, pressure measurements were made under both front feet. Results: At both ages the hoof-pastern axis was broken-...
Development and evaluation of a noninvasive marker cluster technique to assess three-dimensional kinematics of the distal portion of the forelimb in horses. To develop and evaluate a marker cluster set for measuring sagittal and extrasagittal movement of joints in the distal portion of the forelimb in ponies. Methods: 4 ponies. Methods: 5 infrared cameras were positioned on a concrete walkway in a frontal-sagittal arc and calibrated. Four segments were defined: hoof, middle phalanx, proximal phalanx, and metacarpus. Rigid clusters with 4 retroreflective markers were placed on each segment. A static trial was recorded with additional anatomic markers on the medial and lateral joint lines. Those anatomic markers were removed, and kinematic data were...
Radiographic evolution of the forelimb digit in Ardenner horses from weaning to 28 months of age and its clinical significance. Ossification of collateral cartilages is a common radiographic finding in draught horses and indication of a high frequency of interphalangeal osteo-arthropathy have been found in Ardenner horses. This study first aimed at following the evolution of the digits of the forelimbs on radiographic images in a group of 32 Ardenner horses from weaning to 852 +/- 19 days and, secondly, at evaluating the clinical significance of the observed radiographic changes. At 250 +/- 21 days, only 23% of the horses presented a small separate ossification centre of collateral cartilages above the level of the dis...
Collateral ligaments of the distal sesamoid bone in the digit of Equus: re-evaluating midstance function. The distal forelimb of the horse has a complex array of ligaments that play a critical role in determining function of the digit and are often associated with the initiation of foot pathologies. The collateral ligaments of the distal sesamoid bone (CLDS) play an important role in digit stabilization near the end of foot contact and there is also limited evidence to suggest that the CLDS stabilize the proximal interphalangeal joint (PIPJ) during weight bearing. By virtue of their anatomical attachments where the ligaments pass dorsal to the axis of rotation of the PIPJ, it is reasonable to assu...
The effect of hoof trimming on radiographic measurements of the front feet of normal Warmblood horses. The understanding of the normal position of the third phalanx (P3) and the distal sesamoid bone in relation to the size and shape of the hoof capsule in sound horses is helpful in the diagnosis of equine foot lameness. Some measurements on radiographs used to define the position of the pedal bone within the hoof capsule are significantly influenced by hoof trimming and the height of the withers. In this study, the front hooves of 40 Warmblood horses were radiographed twice, eight weeks apart, both before and after their hooves were trimmed by an experienced farrier. Using the software programm...
Arthroscopically assisted arthrodesis of the distal interphalangeal joint with transarticular screws inserted through a dorsal hoof wall approach in a horse. A 16-year-old Thoroughbred gelding was examined because of chronic right forelimb lameness. Results: On radiographs of the right front foot, the distal interphalangeal (DIP) joint space was narrow, and osteophytes and periarticular bony proliferation indicative of severe osteoarthritis were seen. Arthrodesis of the right DIP joint was recommended to improve the horse's comfort on the limb. Results: The horse was anesthetized, and palmar and dorsal arthroscopic approaches were used to remove as much of the articular cartilage as was accessible. Holes were then drilled through the dorsal aspect ...