Chapter 20.3 Malunion Flashcards
What are malunions?
Healed fractures in which anatomical bone alignment was not achieved or maintained during healing.
Which skeletons can malunions involve?
Appendicular skeleton, axial skeleton, or a joint surface.
What is a common outcome of malunions in the appendicular skeleton?
Angular deformity of the limb with a variable functional outcome.
How are malunions in the appendicular skeleton subdivided?
Into two groups based on angular deformities and shortening:
* Minor angular deformities (10º or less) and/or minor shortening (10% or less)
* Major angular deformities (more than 10º) and/or major shortening (more than 10%)
What functional outcome is generally expected for animals in the first group of malunions?
Functional malunion.
What is the functional outcome for animals in the second group of malunions?
Variable degrees of functional impairment.
What is a common site for malunions in the axial skeleton?
The pelvis.
What complication can arise from a malunion in the pelvis?
Reduction in the diameter of the pelvic canal, leading to obstipation, especially in cats.
What challenge do malunions of a diarthrodial joint represent?
unlikely to restore articular function
What can cause malunions?
Inadequate initial fracture reduction or loss of fracture reduction during healing.
Fill in the blank: Malunion is a healed fracture in which ____ was not achieved.
[anatomical bone alignment]
What may lead to deformity in fractures?
Inadequate initial reduction.
What can complicate malunions in very young animals?
Physeal fractures.
Growth may not be evenly distributed across its whole surface.
True or False: Proper application of an appropriate technique guarantees correct healing of fractures.
False.
What are the deformities in the frontal plane?
- Varus (deviation of the segment axis towards the median sagittal plane)
- Valgus (deviation of the segment axis away from the median sagittal plane)
Varus is the deviation of the segment axis towards the median sagittal plane, while valgus is the deviation away from it.
What are the deformities in the sagittal plane?
- Procurvatus (cranial bowing)
- Recurvatus (caudal bowing)
Procurvatus refers to cranial bowing, while recurvatus refers to caudal bowing.
What are the deformities in the axial plane?
- Pronatus (internal rotation)
- Supinatus (external rotation)
Pronatus indicates internal rotation, and supinatus indicates external rotation.
How can a deformity be classified?
Simple or Complex
A deformity is simple if present in one plane, and complex if it affects more than one plane.
What is the fourth kind of deformity?
Shortening
Shortening refers to a decrease in the length of a bone.
How can shortening in a single bone system be compensated?
By extension of adjacent joints
This applies to systems like the humerus or femur.
What is likely to happen when there is shortening in a paired bone system?
Causes incongruity in the alignment of adjacent joints
This occurs in systems such as radius/ulna or tibia/fibula.
What is a malunion?
A healing of a bone in an incorrect position
Malunions are assessed through radiographs.
What should be analyzed in radiographs to investigate malunions?
Extent of varus, valgus, rotational deformities, and length discrepancies
This analysis helps determine the functional problems caused by the malunion.
When should a corrective osteotomy be considered?
When a malunion causes a functional problem
This surgical procedure corrects the positioning of the bone.
What is the treatment for malunions that cause functional problems?
Corrective osteotomies
When are minor shortenings in dogs and cats typically not treated?
When there are no angular deformities
How do dogs and cats compensate for minor shortenings?
By extending the joints a little more than usual
What can be used to stabilize the bone during corrective osteotomies?
Either plates or linear external fixators
What is essential in the preoperative planning for corrective osteotomies?
Correct calculation of the plane of deformity
True or False: The plane of deformity always lies where the callus is present.
False
What type of osteotomy is beneficial for simple deformities?
Dome-shaped osteotomy
What is a significant advantage of dome-shaped osteotomies?
Preserves available bone stock
What might be packed in the osteotomy area?
Cancellous graft
What is recommended when major angular deformities and/or shortening are present?
Use of circular external fixators
What process is used to achieve regenerate tissue in distraction osteogenesis?
Distraction osteogenesis
What is the ideal distraction rate for bone lengthening?
1 mm per day, at a rate of 3-4 times a day
What surgical options are available for correcting pelvic malunions?
Osteotomy of the ilium or distraction of the pubic symphysis
What may be required for articular malunions in surgical correction?
Arthroplasty, joint prosthesis, or arthrodesis
What is the outcome of osteotomizing and levering outward the badly healed ilium?
Improvement in the diameter of the pelvic canal
What is often not restored in the correction of articular malunions?
Full joint congruency
