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Fracture of Distal Phalanx in Horses

(Fracture of third phalanx, os pedis, or coffin bone)

By

James K. Belknap

, DVM, PhD, DACVS, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University

Last full review/revision Sep 2015 | Content last modified Jun 2016

Fracture of the distal phalanx is a fairly common injury that occurs most commonly at high speed (ie, during a race) or less commonly from kicking a firm object (eg, a stall wall). The fracture is caused by concussion and produces a sudden onset of lameness. The lameness is severe if the fracture is intra-articular but may be less severe if only a wing (or solar margin of the distal phalanx) is fractured with no articular component. Distal phalangeal fractures occur more frequently in the forelimb but are also common in the hindlimb. Intra-articular fractures may be easily isolated to the foot; lameness is commonly associated with joint effusion. Nonarticular fractures may require compression of the foot with hoof testers and possibly unilateral palmar digital nerve anesthesia for localization. Lameness is exacerbated by turning the horse or making it pivot on the affected leg. If the fracture does not extend into the joint, the lameness may improve considerably after 48 hr of stall rest.

The clinical signs may be suggestive, but the diagnosis is confirmed by palmar digital nerve block and radiographic imaging. Radiographic confirmation may be difficult immediately after the injury, because the fracture is only a hairline at this stage. Often, more than two views are required before the fracture line is evident. Repeating the radiography several days or weeks later (to allow bone resorption) and using oblique views may be necessary to confirm the presence and exact site of the fracture. Additionally, if the suspected fracture is in a wing of the distal phalanx, unilateral palmar digital nerve anesthesia may be performed to localize the lameness to that side. Determining whether the fracture extends into the distal phalangeal joint is important. Scintigraphy and MRI are other imaging options if a definitive diagnosis is not possible by radiographs.

Conservative treatment of 6–9 mo rest is usually all that is required for fractures not involving the joint. Fractures often heal with a fibrous union, so that, even though the horse returns to soundness, radiographic evidence of the fracture remains. A straight bar shoe with a clip well back on each quarter can be applied to limit expansion and contraction of the heels. In young horses (<3 yr old), fractures into the joint may heal satisfactorily, provided a 12-mo rest period is given. Older horses (>3 yr old) have a much less favorable prognosis, and insertion of a cortical bone screw using interfragmentary compression across the fracture site is indicated; however, infection is a frequent complication, because an extracapsular approach is required. Many fractures heal in the presence of infection, but the screw must be removed at a second surgery to restore the horse to complete working soundness. Unilateral palmar digital neurectomy of racehorses with nonarticular wing fractures has been used to allow return to competition without the delay for complete healing.

OTHER TOPICS IN THIS CHAPTER
Lameness in Horses
Overview of Lameness in Horses
The Lameness Examination in Horses
Imaging Techniques in Equine Lameness
Arthroscopy in Equine Lameness
Regional Anesthesia in Equine Lameness
Disorders of the Foot in Horses
Osseous Cyst-like Lesions in the Distal Phalanx in Horses
Bruised Sole and Corns in Horses
Canker in Horses
Fracture of Navicular Bone in Horses
Fracture of Distal Phalanx in Horses
Keratoma in Horses
Laminitis in Horses
Navicular Disease in Horses
Pedal Osteitis in Horses
Puncture Wounds of the Foot in Horses
Pyramidal Disease in Horses
Quittor in Horses
Quarter Crack in Horses
Scratches in Horses
White Line Disease in Horses
Sheared Heels in Horses
Sidebone in Horses
Thrush in Horses
Disorders of the Pastern and Fetlock
Fractures of the First and Second Phalanx in Horses
Fractures of the Proximal Sesamoid Bones in Horses
Osteoarthritis of the Proximal Interphalangeal Joint in Horses
Palmar/Plantar Metacarpal/Metatarsal Nonadaptive Bone Remodeling in Horses
Sesamoiditis in Horses
Chronic Proliferative Synovitis in Horses
Digital Sheath Tenosynovitis in Horses
Disorders of the Metacarpus in Horses
Tendinitis in Horses
Suspensory Desmitis in Horses
Inferior Check Desmitis in Horses
Bucked Shins in Horses
Exostoses of the Second and Fourth Metacarpal Bones in Horses
Fractures of the Small Metacarpal (Splint) Bones in Horses
Fracture of the Third Metacarpal (Cannon) Bone in Horses
Disorders of the Carpus in Horses
Fracture of the Carpal Bones in Horses
Subchondral Bone Disease of the Third Carpal Bone in Horses
Tearing of the Medial Palmar Intercarpal Ligament in Horses
Osteoarthritis of the Carpus in Horses
Distal Radial Exostosis and Osteochondroma of the Distal Radius in Horses
Carpal Hygroma in Horses
Rupture of the Common Digital Extensor Tendon in Horses
Disorders of the Shoulder in Horses
Developmental Diseases of the Shoulder in Horses
Fractures of the Shoulder in Horses
Bicipital Bursitis in Horses
Infection of the Shoulder in Horses
Suprascapular Neuropathy in Horses
Osteoarthritis of the Shoulder in Horses
Disorders of the Elbow in Horses
Developmental Orthopedic Disease in the Elbow of Horses
Fractures of the Elbow in Horses
Osteoarthritis of the Elbow in Horses
Collateral Ligament Injury in the Elbow of Horses
Disorders of the Metatarsus in Horses
Bucked Shins/Dorsal Cortical Fractures of the Third Metatarsal Bone in Horses
Exostoses of the Metatarsal Bones in Horses
Diaphyseal Fracture of the Third Metatarsal Bone in Horses
Incomplete Longitudinal Fractures of the Plantar Aspect of the Third Metatarsal Bone in Horses
Focal Bone Reaction and Avulsion Fractures of the Third Metatarsal Bone in Horses
Fractures of the Second and Fourth Metatarsal Bones in Horses
Enostosis-like Lesions of the Third Metatarsal Bone in Horses
Disorders of the Tarsus in Horses
Failure of Ossification of the Distal Tarsal Bones in Horses
Osteoarthritis of the Distal Tarsal Joints in Horses
Osteoarthritis of the Talocalcaneal Joint in Horses
Osteoarthritis of the Tarsocrural Joint in Horses
Synovitis/Capsulitis of the Tarsocrural Joint in Horses
Osteochondrosis of the Tarsocrural Joint in Horses
Osteitis of the Calcaneus in Horses
Fractures of the Distal Tarsal Bones in Horses
Fracture of the Talus in Horses
Fracture of the Fibular Tarsal Bone (Calcaneus) in Horses
Fracture of the Lateral Malleolus of the Tibia in Horses
Tarsal Joint Luxation in Horses
Desmitis of the Collateral Ligaments of the Tarsus in Horses
Rupture of the Fibularis (Peroneus) Tertius in Horses
Stringhalt
Curb in Horses
Disorders of the Tarsal Sheath in Horses
False Thoroughpin in Horses
Luxation of the Superficial Digital Flexor Tendon from the Tuber Calcanei in Horses
Gastrocnemius Tendinitis in Horses
Calcaneal Bursitis in Horses
Capped Hock
Disorders of the Stifle in Horses
Osteochondrosis of the Stifle in Horses
Subchondral Cystic Lesions in Horses
Meniscus and Meniscal Ligament Injuries in Horses
Cranial and Caudal Cruciate Ligament Injuries in Horses
Collateral Ligament Injuries in Horses
Intermittent Upward Fixation of the Patella and Delayed Patella Release in Horses
Fragmentation of the Patella in Horses
Patellar Luxation in Horses
Patellar Ligament Injuries in Horses
Gonitis and Osteoarthritis in Horses
Chondromalacia of the Femoral Condyles in Horses
Fractures of the Stifle in Horses
Disorders of the Hip in Horses
Luxation of the Coxofemoral Joint in Horses
Pelvic Fracture in Horses
Osteoarthritis and other Coxofemoral Joint Diseases in Horses
Disorders of the Back and Pelvis in Horses
Spinal Processes and Associated Ligaments in Horses
Articular Process−Synovial Intervertebral Articulation Complexes in Horses
Vertebral Bodies and Discs in Horses
Muscle Strain and Soreness in Horses
Lumbosacral Junction Abnormalities in Horses
Sacroiliac Joint Abnormalities in Horses
Developmental Orthopedic Disease in Horses
Osteochondrosis in Horses
Physitis in Horses
Flexural Deformities in Horses
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Lameness
The lameness examination is an important method to identify musculoskeletal abnormalities. Which of the following abnormalities is NOT observed during a physical and lameness exam? 
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