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Fractures, Abnormal Healing 357

examination of pleural fluid, consider • Intubation and endoscopy may inadvertently SUGGESTED READING
long-term (4-6 weeks) antibiotic treatment. force tracheal foreign bodies toward the Tenwolde AC, et al: The role of bronchoscopy in
tracheal bifurcation or into the bronchi.
VetBooks.ir Technician Tips Affected animals may require an emergency foreign body removal in dogs and cats: 37 cases Diseases and Disorders
• Cuterebra larvae may be tracheal FBs,
especially in cats.
(2000-2008). J Vet Intern Med 24:1063-1068,
thoracotomy and intubation of the distal
2010.
• During rhinoscopy for FBs, fluids exit trachea or bronchus through the thoracotomy AUTHOR: Karen M. Tobias, DVM, MS, DACVS
site; materials should be available for clip-
the nares and nasopharynx; therefore, the ping, prepping, and thoracotomy. EDITOR: Megan Grobman, DVM, MS, DACVIM
endotracheal tube should be in place with the
cuff properly inflated. Pack the oropharynx Client Education
with laparotomy sponges. • Acute cough in high-performance sporting
• Teeth and pieces of dental calculus may dogs during hunting or harvest season may
become tracheal or bronchial foreign bodies indicate tracheobronchial FB.
if not removed from the mouth after dental • Provide indestructible bones and toys that
cleaning. are appropriately sized for the dog.

Fractures, Abnormal Healing Client Education
Sheet

BASIC INFORMATION ○ Minimal or no callus formation present; • Poor vascular supply to the fracture site
fracture gap may be increased; bone frag- ○ Disruption of soft tissues during initial
Definition ment edges may be sclerotic or tapered trauma or surgery
• Delayed union: bone healing progressing at ○ To achieve union, the fracture must be ○ Placement of implants that impede blood
a slower rate than anticipated rigidly stabilized, blood supply must be supply to the bone
• Nonunion: failure to achieve bony union of improved, and osteogenesis stimulated. • Inadequate fracture reduction; interposition
a fracture • Nonunions of either type may form pseud- of soft tissue in the fracture gap
• Malunion: fracture healing with abnormal arthroses; the fracture ends cease healing Other factors can influence normal bone
bone/limb alignment and/or abnormal activities and instead form a false joint healing:
function that may include joint-like fluid within a • Polytrauma
surrounding capsule. • Pre-existing metabolic diseases or other
Epidemiology Malunion: fracture has healed but with shorten- catabolic conditions
SPECIES, AGE, SEX ing, angulation, or rotational malalignment of
Older patients may take longer to heal. the fragments. DIAGNOSIS

GENETICS, BREED PREDISPOSITION HISTORY, CHIEF COMPLAINT Diagnostic Overview
• Toy-breed dogs have increased incidence of • Continued lameness after fracture • Diagnosis of delayed or nonunion requires a
avascular nonunion with radius/ulna and stabilization complete patient history and timeline since
possibly metacarpal/metatarsal fractures. • Abnormal limb angulation injury. The ultimate diagnosis is based on
• Feline tibial fractures may be at greater risk • Decreased muscle mass of the affected physical exam and comparison of sequential
for nonunion than those in dogs. limb radiographs.
• Clinical findings include decreased limb
Clinical Presentation PHYSICAL EXAM FINDINGS usage, sudden changes in limb usage, and
DISEASE FORMS/SUBTYPES • Lameness increased bone pain; fracture stability is unaf-
Delayed union: failure of fractures to heal • Muscle atrophy fected unless implant failure has occurred.
within the expected period (usually about 16 • Crepitus or obvious instability of the affected • Delayed unions and nonunions are normally
weeks in adult dogs and cats, but this varies bone identified during routine follow-up exams
with the animal’s age and health as well as with • Palpably excessive callus formation in the by lack of radiographic evidence of bone
the nature of the fracture). Delayed unions face of physical instability healing (blurring of fracture lines, increased
are differentiated from normal healing and • Limited range of joint motion or discomfort fracture gap opacity, callus formation) at a
nonunions using sequential radiographs and on manipulation of the affected limb time when healing would be expected.
a timeline from the initial injury. • Draining tracts or evidence of inflammation • Malunions are often first noted in animals
Nonunions are divided into categories to over the fracture site suggests osteomyelitis. that have changed owners, recently been
help guide treatment: adopted, or found as strays. They may or
• Viable (vascular; hypertrophic and Etiology and Pathophysiology may not cause lameness.
oligotrophic) Fracture environment, the patient’s ability to
○ Usually result from fracture instability heal, and decisions about case management Differential Diagnosis
○ Associated with nonbridging callus. affect fracture healing. Several factors can Nonunion/delayed union differential diagnoses:
The biological environment is generally impede bone healing: • Normal healing for that individual
adequate for fracture healing; union is • Infection • Infection
achieved by neutralization of uncontrolled • Excessive fracture gap or bone loss • Neoplasia
fracture forces. • Inadequate fracture stabilization: motion at Malunion differential diagnoses:
• Nonviable (avascular or atrophic) the fracture site shears off blood supply and • Congenital or breed-associated bone malfor-
○ Usually result from poor blood supply prevents progression of healing from fibrous mations (e.g., dwarfism, chondrodystrophic
combined with fracture instability tissue to bone breeds)

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