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Fractures of the Proximal Sesamoid Bones in Horses

By

Matthew T. Brokken

, DVM, The Ohio State University

Last full review/revision Sep 2015 | Content last modified Oct 2015

Fractures of the proximal sesamoid bones are classified according to their location in the bone. The most common sesamoid fractures in Standardbreds and Thoroughbreds are apical. They are caused by overextension and often are associated with suspensory ligament damage. The lateral proximal sesamoid in the hindlimb of Standardbreds may be fractured as a result of torque forces induced by shoeing with a trailer-type shoe. Other fractures include mid-body, basilar, abaxial, axial, or comminuted, and they may involve one or both sesamoids. Most, apart from some abaxial and base fractures, are articular. Clinical signs include heat, pain, and acute lameness, which is exacerbated by flexion of the fetlock. There is often hemarthrosis and synovial effusion of the metacarpal/tarsophalangeal joint. Diagnosis is confirmed radiographically. Of Thoroughbred racehorses ≥2 yr old, 82% of horses with apical sesamoid fractures removed arthroscopically ran at the same or at an improved level. Horses with apical fractures of the forelimb medial proximal sesamoid are less likely to race after fragment removal. The presence of suspensory desmitis (see Suspensory Desmitis in Horses Suspensory Desmitis in Horses Interosseous medius (suspensory ligament) of the horse. Injuries of the suspensory ligament (interosseous muscle) are common in forelimbs and hindlimbs of horses. Lesions are typically classified... read more Suspensory Desmitis in Horses ) in the affected limb also decreases the prognosis after surgery. Horses with apical sesamoid fractures in the forelimbs are less likely to race than those with fractures in the hindlimbs (55% vs 86%). Size and shape of apical sesamoid fractures does not appear to affect racing performance. Mid-body fractures typically require reduction using lag screw(s) fixation with a prognosis of 75% (44% in another study) to return to racing. The prognosis for basilar fractures involving a portion of the sesamoid is fair compared with that for fracture of most of the base or in horses with associated articular disease (poor prognosis). Complete disruption of the suspensory apparatus, including fractures of both sesamoid bones, is a catastrophic injury that may be accompanied by vascular compromise; however, some horses can be salvaged for breeding by surgical arthrodesis of the fetlock joint.

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
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Musculoskeletal Disorders in Large Animals
A seven-year-old Quarter horse gelding presents with a 1-week history of mild lameness. During the examination, the horse raises his head as he places weight on his left forelimb and drops it when placing weight on the right forelimb. Which limb is most likely affected in this horse?
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