Fixation evaluation, fracture disease, and fracture healing Flashcards
What are the 4 “A’s” of radiographic evaluation when reviewing post-op or recheck radiographs of a fracture repair?
Apposition
Alignment
Apparatus
Activity
What are you looking for when assessing apposition on post-op or re-check radiographs?
- Are the fracture edges touching?
- Only very important in articular fractures
- Not important in biological osteosynthesis
What are you looking for when assessing the activity level in post-op or re-check rads?
- Is there evidence of:
- Bone healing–callus spanning across fracture
- Infection–more lucency, too much periosteal activity
- Osteopenia
- Malunion
Other than obvious implant migration, what is a radiographic change that would be indicative of implant loosening?
Radiolucency around screw heads
ALWAYS compare to original radiographs!
What radiographic changes are consistent with osteomyelitis?
Proliferative/lytic appearance
What are the 2 types of non-union?
- Viable = biologically active fracture with cartilage and fibrous tissue between fracture ends
- Non-viable = fracture ends are sclerotic with rounded bone edges and visible fracture gap
What is the recommended treatment for non-union fractures?
Appropriate stabilization and cancellous bone autographs
Partial mandibulectomy is an option for treatment of chronic non-union of the mandible
What is the pathogenesis of quadriceps contracture?
- Muscle fibers are replaced by fibrous tissue
- Adhesions form between muscle and bone
- Changes result in severe decrease in limb motility
- Periarticular fibrosis/joint ankylosis/DJD further inhibits limb function
- Often irreversible
What are the risk factors associated with quadriceps contracture?
- Distal femoral fractures
- Young patients (< 6mo)
- Prolonged immobilization
- Extensive muscle/ST trauma
What treatment options are available for quadriceps contracture?
Rehabilitation (ROM exercises + NSAIDs) to prevent muscle atrophy and scar tissue
Treatment is rarely successful
T/F: The prognosis for quadriceps contracture (with treatment) is poor for full function and guarded for partial function
TRUE
What other morbidity is associated with overly rigid fixation and limb immobilization for treatment of a fracture?
Disuse osteoporosis
Muscle atrophy
Ligamentous laxity
Also: cartilage atrophy, digital flexor contracture, and fracture-associated sarcoma
What is the difference between disuse osteoporosis and muscle atrophy?
- Disuse osteoporosis
- Decrease in stress application to the bone –> increased osteoclast activity
- Can occur with casts and excessively strong implants/fixators
- Muscle atrophy
- Secondary to disuse or immobilization
- Reversible
- Can take significant time to return to normal
What is ligamentous laxity?
- Associated with muscle atrophy from disuse or immobilization
- Loose ligaments result in joint instability
- Should resolve with improved muscle tone
What radiographic changes are expected for an aggressive, neoplastic bone lesion?
- Cortical lysis
- Periosteal reaction
- +/- mineralization of surrounding soft tissues
- Loss of trabecular pattern
- Lack of distinct border between normal and abnormal bone
What are some differential diagnoses to keep in mind when observing radiographic changes due to an aggressive, neoplastic bone lesion?
- Osteomyelitis
- Osteosarcoma
- Bacterial, fungal infections
- CSA, FSA, HSA
- Lymphoma
- Bone cyst
Which osteosarcoma treatment option is associated with the longest MST?
Limb-sparing surgery–local removal of tumor with wide margins and the bone is replaced with graft, prosthesis or regenerated via bone transport osteogensis
What is the purpose of amputation of a limb affected with osteosarcoma if there is no change in MST?
Removes the source of pain, especially in cases of pathological fracture
What are the most common sites for metastasis of osteosarcomas?
Lungs, local LN, other bones
(Usually located towards the elbow and away from the knee)
What staging is recommended with osteosarcomas?
- 3 view thoracic rads or thoracic CT
- CT >>> rads when diagnosing pulmonary metastasis
- Aspiration of any enlarged LN
- CBC/chemistry/UA
- Increased ALKP is assoc. w/ poorer prognosis
T/F: Micrometastases are present in most patients at time of initial diagnosis
TRUE
What is the gold standard for obtaining a diagnosis of a bone lesion?
Biopsy
What bone tumor locations are amenable to treatment by limb-sparing?
Distal radial lesions have the best outcome
Other than osteosarcomas, what primary bone tumors are diagnosed in small animal patients?
Chondrosarcoma, fibrosarcoma, hemangiosarcoma
What tumor types are specific to the digits?
- Dogs
- Squamous cell carcinoma and melanoma
- Cats
- Squamous cell carcinoma, fibrosarcoma, adenocarcinoma, osteosarcoma, hemangiosarcoma
