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Fractures of the First and Second Phalanx in Horses

By

Matthew T. Brokken

, DVM, The Ohio State University

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

Fractures of the first/proximal phalanx (P1) may occur in any type of horse used for performance. They may be small osteochondral “chip” fractures along the dorsal margin of the proximal joint surface, sagittal (complete or incomplete), or comminuted. Another category involves fragments of the palmar or plantar proximal aspect of P1, which may be associated with osteochondrosis.

“Chip” fractures of the dorsoproximal aspect of P1 typically involve the medial aspect of the joint and occur in horses that exercise at speed. These fractures are normally traumatic in origin and result from hyperextension of the fetlock joint. Acute lameness and increased effusion in the fetlock joint along with sensitivity to firm flexion of the fetlock are clinical signs that a fracture may be present and radiographic examination indicated. In nonracing breeds, a chip fracture may be present on radiographs, but its clinical significance should be determined with diagnostic analgesia before being implicated as a source of lameness.

The cause of proximopalmar and proximoplantar osteochondral fractures is questionable; one thought is that they are from osteochondrosis, the other is that they are fractures. Axial fractures are classified as type I fractures and are generally articular. Type II fractures are located abaxially and typically have minimal articular cartilage present. Type I fractures are generally associated with lameness at speed with clinical signs similar to those of dorsoproximal P1 fractures. These fractures are more common in the hindlimb, and intra-articular diagnostic analgesia is often needed to implicate these fractures as a cause of lameness.

Diagnosis is confirmed by radiography. A number of oblique radiographic views may be necessary to ensure visibility of the fractures. For palmar or plantar osteochondral fractures, oblique radiographic views with the beam raised ~20° from horizontal may be more helpful for identification. The diagnosis of sagittal or comminuted fractures of P1 is typically straightforward, with marked lameness and swelling. Incomplete, short sagittal fractures can be more difficult to diagnose and may require special radiographic views off of dorsopalmar/plantar and/or nuclear scintigraphy in the initial stages, because the fracture line may be difficult to detect radiographically.

Osteochondral “chip” fractures can be removed arthroscopically with an excellent prognosis if no other abnormalities within the joint exist. Routine, nondisplaced sagittal P1 fractures can be repaired by internal fixation using screws placed in lag fashion via stab incisions. More complex P1 fractures typically require open reduction and repair via lag screws to allow accurate realignment of the articular surface of the fetlock to limit postoperative arthritis. Careful attention should be paid to the fracture configuration to ensure that all components are incorporated in the repair. In some circumstances, CT may aid an accurate diagnosis and reconstruction of the fracture. Conservative treatment of severely comminuted fractures involves immobilization with a plaster or fiberglass cast for up to 12 wk, with or without the use of transfixation pins through the third metacarpal/tarsal bone. Complications of P1 fracture repair include implant failure, poor alignment at the fracture site leading to secondary arthritis, and contralateral limb laminitis.

Fractures of the second/middle phalanx (P2) are most common in Quarter horses and typically affect the hindlimbs. Whereas osteochondral “chip” fractures are common off of proximal P1, osteochondral fractures are relatively uncommon off of P2. The most common fractures of P2 are either palmar/plantar eminence fractures of proximal P2 or comminuted fractures. Treatment of most P2 fractures is either with internal fixation with a combination of plate(s) and screws and/or a transfixation pin cast. Residual lameness typically is present and depends on the degree of osteoarthritis that develops in the distal interphalangeal joint and, to a lesser extent, the proximal interphalangeal joint (if not arthrodesed in the fracture repair). Prognosis depends on how comfortable the horse will be after fracture stabilization to limit the risk of contralateral limb laminitis.

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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