interpretation of appendicular skeleton (veterinary)
TRANSCRIPT
Interpretation of
Appendicular Skeleton
BY: Girjesh Upmanyu
Positioning of Patient
In the appendicular skeleton, patient
should consist of a minimum of two
orthogonal projections, a lateral view
and a craniocaudal (dorsopalmar,
dorsoplantar) view.
If a bone lesion is suspected, it is
important that the field of view include
the joint proximal and distal to the
bone of interest.
Cranioproximal-craniodistal view of canine proximal
humerus for evaluation of bicipital groove for changes
associated with biceps or supraspinatus tendinopathy
Flexed dorsoplantar view of
canine tarsus for
evaluation of trochlea of talus
for changes associated with
osteochondrosis, without
superimposition of calcaneus.
Dorsal acetabular rim view of canine pelvis for
evaluation of lateral aspect of acetabulum for
Remodeling.
OBLIQUE PROJECTIONS
Oblique views are intended to project
different edges of a joint or region.
Oblique views maximize the chances
of projecting an edge lesion
tangentially in a complex joint.
Aggressive versus nonaggressive
bone lesions
Aggressive process: such as a tumor or infection.
Nonaggressive process: such as a bone cyst.
The aggressiveness of a bone lesion is related to three criteria: -
(1) whether or not there is destruction of the cortex.
(2) the character of any periosteal reaction, and
(3) the distinctness of the boundary between the bone lesion and the normal bone, called the transition zone.
Destruction of the Cortex
Many aggressive bone diseases are characterized by destruction of the cortex. e.g, malignant bone tumors are often associated with destruction of the cortex, through mechanisms such as increased matrix metalloproteinase activity or increased osteoclast activity.
Bone infections also can result in destruction of cortical bone, e.g. by an alteration in the inflammatory response that disrupts the homeostatic balance of bone matrix deposition and resorption, thereby mediating bone destruction.
For cortex destruction to be apparent radiographically, the region of destruction must be hit tangentially by the primary x-ray beam.
Classification of bone
destruction
• Geographic bone lysis is a large, relatively well-defined region of bone loss
Geographical
• Moth-eaten bone lysis gets its name from the appearance of moth damage in cloth
• It is characterized radiographically as multiple small regions of lysis
Moth-eaten
• Permeative lysis is the least well-defined lytic pattern, where the bone lysis is confluent and not demarcated clearly from adjacent normal bone.
• Permeative lysis is the most common pattern of bone lysis that accompanies an aggressive bone lesion
Permeative
Periosteal Reaction
An active periosteal reaction is one where the margin of the periosteal reaction is irregular and not smooth.
periosteal irregularity is the basic change that dictates the lesion is aggressive.
a nonaggressive periosteal reaction is characterized by a smooth edge to the periosteal new bone growth.
Transition Zone
The character of the junction of the
bone lesion with the adjacent normal
bone is termed the transition zone.
The transition zone is typically
evaluated in the medullary cavity of
the bone, and its character is a clue as
to the aggressiveness of the lesion.
Thank You