Equine P3 Fracture ClassificationJames Montgomery, DVMJune 1, 2009

Deuce Acc # 1097757 year oldFemaleQuarter horse

Hx: Possible P3 fracture, right hind

Deuce Acc # 109775Parasagittal (Type II) fracture of distal phalanx

Deuce Acc # 109775

Classification system

Type I- Non-articular of Palmar or plantar process

Type II- Articular fxs from distal interphalangeal joint to solar margin

Type III- Articular midsagittal fx divides into equal parts

Type IV- Articular fracture - Extensor process

Type V- Articular comminuted body fx Type VI- Solar margin only

Type VII Palmar process in the foal

P3 FracturesTrauma most common cause

Type VI fractures more common than the other 5 types combined

Make sure 65 DP radiographs are not overexposed may miss Type VI fractures

Fracture healingDifficult to assess progression radiographically minimal amount of callus formationFractures of extensor process produce the greatest amount of new boneTreatment by corrective shoeing and stall rest healing in 3 to 19 monthsYoung horses and nonarticular fractures show most rapid and complete progression to bone union

PrognosisReturn to athletic activity is good for type I

Guarded for types II and IV

Solar margin (type VI) fractures have a good prognosis if not associated with laminitis or severe pedal osteitis

Differentiating fracture from artifactBoth and acute Type II or III fracture and packing artifact can appear as a linear lucent finding3 factors to help differentiateClinical signs fracture usually seriously lameFracture will extend to and end at the margins of P3 packing artifact may extend beyond the margins of P3Linear lucent packing artifacts extend obliquely from the heel (abaxially) toward the toe (axially)Type II fractures run obliquely from the solar margin of the quarter (abaxially) towards the articulation (axially)Type III fractures run sagitally from the toe to the articulation

Type II P3 Fracture

Type VI P3 Fracture

Palmar Process Fractures in the FoalOssicles of the medial and/or lateral palmar and plantar processes of P3 are seen in foals from a few weeks to a year of ageThese are Type VII fractures rather than secondary centers of ossification or developmental orthopedic disease (DOD)May be seen in club-footed foals or in foals with or without clinical signs of lameness

Palmar Process Fractures in the FoalTwo radiographic patterns associated with this type of fracture are:Triangular bony fragment at the palmar aspect of the distal angle of the palmar processOblong fragment separated from P3 by a lucent line extending 1-3 from the incisure of the palmar process to the solar marginHealing radiographically complete in an average of 8 weeks with return to being sound

ReferencesPack L. Equine Imaging. VCA 341 lecture, Atlantic Veterinary College, University of Prince Edward Island.Riedesel EA. The Phalanges. In Thrall DE, ed. Textbook of Veterinary Diagnostic Radiology, 5th ed (St. Louis, MO: Saunders Elsevier, 2007) pp. 432-3.