## Overview The coffin bone (distal phalanx or third phalanx) is the terminal bone of the limb and sits entirely inside the hoof capsule. Because it is enclosed by the rigid hoof wall, fractures of this bone behave differently from fractures of other bones. The hoof itself can help stabilize some fractures once the wall is supported, but the same enclosure also makes diagnosis and surgical access more challenging. Coffin bone fractures are classified according to their location and whether the fracture line enters the distal interphalangeal (coffin) joint. Non-articular fractures (commonly wing or solar-margin fractures that do not enter the joint) generally carry a better prognosis with conservative management. Articular fractures (those that enter the coffin joint) carry a higher risk of osteoarthritis. Selected articular fractures, especially some type II and type III fractures, may benefit from surgical fixation, but large retrospective data do not show surgery is uniformly superior to conservative treatment across all articular distal phalanx fractures. Comminuted fractures that involve the joint have the poorest outlook. Most coffin bone fractures result from acute trauma or severe concussion. A smaller number are pathological fractures that occur secondary to underlying bone disease such as chronic laminitis or pedal osteitis, particularly solar-margin fractures. ## Causes The majority of coffin bone fractures are traumatic. Common scenarios include high-speed work on hard or uneven ground, stepping on a rock, kicking a wall or solid object, or landing awkwardly from a jump. Forelimbs are more frequently affected than hindlimbs, reflecting the greater weight they carry. Solar-margin fractures (Type VI) are sometimes associated with demineralization of the bone and can occur secondary to chronic laminitis or pedal osteitis. In foals, a specific pattern of solar-margin fracture of the palmar or plantar process (Type VII) is recognized and is thought to result from excessive tensile forces. ## Diagnosis Your veterinarian will perform a lameness examination, including hoof-tester response and, when appropriate, diagnostic nerve blocks to confirm that the pain originates in the foot. Radiography is the primary imaging method. Multiple views are usually required, and special oblique projections materially improve detection of palmar or plantar process fractures. Some fractures are subtle initially, and repeat high-quality imaging may be needed if clinical suspicion remains high. Computed tomography (CT) is best used as a problem-solving and surgical-planning tool for subtle, complex, or articular fractures. It is not a routine requirement for every suspected coffin bone fracture. ## Treatment Treatment is guided by fracture configuration rather than by a single protocol. Non-articular fractures (most Type I wing fractures and many solar-margin fractures) are typically managed conservatively with stall rest for several months. External hoof support with a foot cast or a bar shoe fitted with a rim or multiple clips is commonly used. The largest multicentre study did not find that hoof immobilisation itself improved outcome. Selected articular fractures, especially some type II wing fractures and type III sagittal fractures, may benefit from surgical fixation. Small extensor-process fragments can be removed arthroscopically. Larger articular fractures may be compressed with a lag screw placed through the hoof wall. Surgical approaches carry a risk of infection, which may require later screw removal. Conservative management of articular fractures is also used and is not uniformly inferior. In one retrospective study of type III fractures, 3D-assisted surgery was associated with fewer radiographic cases of distal interphalangeal joint osteoarthritis than conservative treatment, but recovery time was not significantly different. Severely comminuted fractures that involve the joint are often not amenable to internal fixation. Comfort can be difficult to achieve, and euthanasia is sometimes the most humane option. ## Recovery and Prognosis Recovery time is measured in months. Non-articular fractures managed with rest often return to soundness, with reported success rates above 90 percent for return to intended use in large case series. Articular fractures have a more guarded outlook; success rates around 70 percent have been reported, and the development of osteoarthritis in the coffin joint is a common reason for persistent lameness. In one retrospective study of type III fractures, 3D-assisted surgery was associated with fewer radiographic cases of distal interphalangeal joint osteoarthritis than conservative treatment, but recovery time was not significantly different. Radiographic healing often lags behind clinical improvement. The fracture line may remain visible long after the horse is sound. Return to work is therefore based primarily on clinical comfort rather than on complete radiographic resolution. Full athletic recovery commonly requires six to twelve months. ## Prevention No management practice has been shown in controlled studies to prevent distal phalanx fractures. Avoiding prolonged work on hard or rocky ground, maintaining good footing in turnout areas, and managing underlying conditions such as chronic laminitis or thin soles that can predispose to pathological solar-margin fractures are plausible risk-reduction steps, but their effectiveness has not been directly tested.
Sudden onset of severe lameness, often non-weight-bearing; strong bounding digital pulse; increased heat in the hoof; marked pain response to hoof testers over the affected area; reluctance to move or shifting weight; in some articular cases, swelling or effusion at the coronary band
## Overview The coffin bone (distal phalanx or third phalanx) is the terminal bone of the limb and sits entirely inside the hoof capsule. Because it is enclosed by the rigid hoof wall, fractures of this bone behave differently from fractures of other bones. The hoof itself can help stabilize some fractures once the wall is supported, but the same enclosure also makes diagnosis and surgical access more challenging. Coffin bone fractures are classified according to their location and whether the fracture line enters the distal interphalangeal (coffin) joint. Non-articular fractures (commonly wing or solar-margin fractures that do not enter the joint) generally carry a better prognosis with conservative management. Articular fractures (those that enter the coffin joint) carry a higher risk of osteoarthritis. Selected articular fractures, especially some type II and type III fractures, may benefit from surgical fixation, but large retrospective data do not show surgery is uniformly superior to conservative treatment across all articular distal phalanx fractures. Comminuted fractures that involve the joint have the poorest outlook. Most coffin bone fractures result from acute trauma or severe concussion. A smaller number are pathological fractures that occur secondary to underlying bone disease such as chronic laminitis or pedal osteitis, particularly solar-margin fractures. ## Causes The majority of coffin bone fractures are traumatic. Common scenarios include high-speed work on hard or uneven ground, stepping on a rock, kicking a wall or solid object, or landing awkwardly from a jump. Forelimbs are more frequently affected than hindlimbs, reflecting the greater weight they carry. Solar-margin fractures (Type VI) are sometimes associated with demineralization of the bone and can occur secondary to chronic laminitis or pedal osteitis. In foals, a specific pattern of solar-margin fracture of the palmar or plantar process (Type VII) is recognized and is thought to result from excessive tensile forces. ## Diagnosis Your veterinarian will perform a lameness examination, including hoof-tester response and, when appropriate, diagnostic nerve blocks to confirm that the pain originates in the foot. Radiography is the primary imaging method. Multiple views are usually required, and special oblique projections materially improve detection of palmar or plantar process fractures. Some fractures are subtle initially, and repeat high-quality imaging may be needed if clinical suspicion remains high. Computed tomography (CT) is best used as a problem-solving and surgical-planning tool for subtle, complex, or articular fractures. It is not a routine requirement for every suspected coffin bone fracture. ## Treatment Treatment is guided by fracture configuration rather than by a single protocol. Non-articular fractures (most Type I wing fractures and many solar-margin fractures) are typically managed conservatively with stall rest for several months. External hoof support with a foot cast or a bar shoe fitted with a rim or multiple clips is commonly used. The largest multicentre study did not find that hoof immobilisation itself improved outcome. Selected articular fractures, especially some type II wing fractures and type III sagittal fractures, may benefit from surgical fixation. Small extensor-process fragments can be removed arthroscopically. Larger articular fractures may be compressed with a lag screw placed through the hoof wall. Surgical approaches carry a risk of infection, which may require later screw removal. Conservative management of articular fractures is also used and is not uniformly inferior. In one retrospective study of type III fractures, 3D-assisted surgery was associated with fewer radiographic cases of distal interphalangeal joint osteoarthritis than conservative treatment, but recovery time was not significantly different. Severely comminuted fractures that involve the joint are often not amenable to internal fixation. Comfort can be difficult to achieve, and euthanasia is sometimes the most humane option. ## Recovery and Prognosis Recovery time is measured in months. Non-articular fractures managed with rest often return to soundness, with reported success rates above 90 percent for return to intended use in large case series. Articular fractures have a more guarded outlook; success rates around 70 percent have been reported, and the development of osteoarthritis in the coffin joint is a common reason for persistent lameness. In one retrospective study of type III fractures, 3D-assisted surgery was associated with fewer radiographic cases of distal interphalangeal joint osteoarthritis than conservative treatment, but recovery time was not significantly different. Radiographic healing often lags behind clinical improvement. The fracture line may remain visible long after the horse is sound. Return to work is therefore based primarily on clinical comfort rather than on complete radiographic resolution. Full athletic recovery commonly requires six to twelve months. ## Prevention No management practice has been shown in controlled studies to prevent distal phalanx fractures. Avoiding prolonged work on hard or rocky ground, maintaining good footing in turnout areas, and managing underlying conditions such as chronic laminitis or thin soles that can predispose to pathological solar-margin fractures are plausible risk-reduction steps, but their effectiveness has not been directly tested.
Sudden onset of severe lameness, often non-weight-bearing; strong bounding digital pulse; increased heat in the hoof; marked pain response to hoof testers over the affected area; reluctance to move or shifting weight; in some articular cases, swelling or effusion at the coronary band