PELVIS, HIP: 56, 57, 58, 59 Flashcards
How many fracture configuration can be seen in pelvic fractures?
160 total, with 19 repeatedly observed (in 52% of all cases)
anatomy of the lumbosacral trunk
it becomes the sciatic nerve after being joined by the 2° sacral nerve, and passing over the greater ischiatic notch and exit the greater ischiatic foramen
percentage of recovery of animal with peripheral nerve injury
15% had permanent loss of linb function
Pelvic canal ratio
hamilton 2009. A-B= cranial border sacrum
C-D= medial cortex acetabulum. 0.97 +- 0.025 in normal cats.
reduction of <10% mild, 10-30% moderate, >30% severe
typical pattern for ilium fractures
from cranioventral to caudodorsal, immediately caudal to the sacroiliac joint
position of the lumbosacral trunk in respect to the ilium body
medial and dorsal
in lateral plating of the ilium, where does screws tipically pull out?
cranial fracture segment
acetabular fractures classification
simple, transverse, oblique or comminuted
location: cranial, dorsal, caudal, central
prevalence of unilateral and bilateral SI luxation fracture
77% unilateral, 23% bilateral
do cats have a sacral notch?
only 34% of cats and 98% of dogs
screw loosening in SI luxation with screw >60% width sacrum
7%
classification of sacral fractures
1) alar
2) foraminal
3) transverse
4) avulsion
5) comminuted
most common pelvic fractures?
pelvic fractures
name the primary stabilizers of the hip joint
1) ligament of the head of the femur
2) joint capsule
3) dorsal acetabular rim
incidence of femural luxation on all luxation
90%
what percentage of femural luxation are craniodorsal?
75%
incidence of relaxation after closed reduction of COX-FEM luxation
more than 50%
name 5 techniques for augmentation of closed reduction
1) Ehmer sling: 10 to 14 days, relaxation 15-71%
2) Hobbles
3) Ischioilial pinning: 2-4 weeks
4) External skeletal fixators
5) transarticular pinning
median success rate after open reduction
+- 85%
Name 12 procedures for open reduction
1) capsulorraphy
2) prostethic capsule repair
3) transposition of the greater trochanter
4) transarticular pinning
5) toggle rod: 6% relaxation
6) fascia lat loop stabilization
7) transposition of the sacrotuberous ligament
8) extra-articular iliofemoral suture
9) surgical stabilization of ventral luxation
10) femoral head and neck excision
11) TPO/DPO
12) THR
caudal acetabular fractures should always be managed conservatively. T or F
F. caudal acetabulum has weightbearing load. without intervention faster progression to osteoarthritis
what is the main responsible to maintain hip joint stability during the first months of life?
ligament head of the femur
breifly describe the 2 biomechanic principles associated with funcional subluxation of the hip
1) forces crossing the joint increase
2) area over wich the forces are transmitted decreases
lower cutoff value for Distraction Index
0.3
Name all the proposed factors that can lead to hip joint laxity
1) joint fluid
2) pelvic muscle mass
3) hormonal factors
4) weight and growth
5) nutrition
6) environmental
7) other
pectineal myectomy or tenotomy reduces incidence of hip displasia. T or F
F
progression of osteoarthritis lead to thightening of the capsule. T or F
False. greater osteoarthritis = greates laxity.
all dogs with hip displasia have a wide based stance. T or F
F: initially wide stance to help with hip reduction. As it progresses, develop narrow-base to degrease discomfort caused by reduction and then subluxation.
Negative Ortolani test is highly indicative of a sound hip. T or F
F: 50 % ortolani negative had hip joint laxity measured by DI
what sign can be confused with a morgan’s line (caudolateral curvilinear osteophyte) ?
puppy line. same position, but shorter, more diffuse, more subtle. Younger than 18 MO, self limiting.
distraction index always correlate with both ortolani sign. T or F
F: the presence of osteoarthritis weaken the correlation.
50% dogs with DI >0.3 had normal ortolani.
ultrasonography of the hip has an high rate of false…….
positive. results in overtreatement in children.
name 3 main cons of ultrasound for early diagnosisi of hip displasia
1) subjectivity/imprecision in repeated measurements
2) absence of reference ranges
3) variables at 16-49 days do not correlate with diagnosis of Hip displasya at 12 to 24 months.
theorical characteristics of the ideal hip screening tool
1) accurately identify unwanted phenotype (es. hip extended, norberg do NOT correlate with OA progression)
2) interobserver reliability
3) continuous ratio scale; not intervals
4) early diagnosis
5) valuable tool for estimate breeding value (must have an hereditary component)
6) selection pressure: genetic change towards better hips.
Mass selection (evaluate just the individual phenotype) is adequate for highly or lower geritable traits?
highly! (>0.5). as it decrease (<0.35), increasingly important to consider relative’s phenotype
anatomic caracteristics of pelvic symphysis
is a synchondrosis that trasforms in synostosis
time to ossification of pelvic symphysis
2-6 years (fibrocartilage replaced by bone)
age at wich greatest changes in acetabular coverage is seen with JPS
12 W
what muscles need to be retracted from pubic sympyhysis?
gracilis and adductor
Gatineau correlation between reduction angle and development of OA: angle?
less than 15° less chances of developing OA
surgical approach to the pubis
1) pectineus muscle
2) iliopectineal eminence palpable cranially, avoid deeper medial circumflex femural artery
3) elevate periosteum from cranial (IP eminence to caudal (obturator foramen)
4) osteotomy
approach to ischium for ischial osteotomy
1) dorsal incision
2) elevation internal obturator dosally, avoid pudendal nerve
3) ventral elevation semim, semit, internal obturator (to evaluate complete cut
the sacroiliac ligament may remain attacched to caudal iliac segment when….
osteotomy is performed perpendicular to iliac body. Better to perform osteotomy perpendicular to long axis pelvis
rate of screw losening following DPO
3.2%
rate of screw losening for Locking Pelvic osteotomies plates
0.4%
what is stress shielding and what does it causes
a) implant stiffer than bone
b) bone resorption (result of disuse atrophy)
what is the primary cause of aseptic losening?
wear debris
How it’s called the science that studies bearing surfaces/friction lubrication articular surfaces?
Tribology
name the various types of wear experienced by a prostethic component
1) adhesive wear
2) abrasive wear
3) Fatigue wear
4) erosive wear
5) impingement wear
6) corrosive wear
Ceramic has a similar elastic modulus than bone T or F
F: almost 300 greater than cancellous bone. Backing with metal to prevent aseptic losening secondary to modulus mismatch
Articulations combinations available in veterinary and lowest wear rates
1) vet only available metal on polyethylene
2) lower wear ceramic on ceramic.
ideal micromotion to allow bone ingrowth (osseointegration)
below 20 um. (over 150 um fibrous interface will develop).
benefit of hydroxiapatite
1) osteoconductive
2) calcium phosphate base
3) prevent migration of wear debris
normal hip joint extension and flexion angles
148 ; 118 °
the greater the jumping –>
lower is the resistance to luxation
lower production of wear debris
T or F
F: greater distance femural head must trave befor luxation occur –> higher resistance to luxation, increased production of wear debris
name the 3 descriptors of acetabular component placement
1) version (15-20°)
2) angle of lateral opening
3) inclination
what should happen in acetabulum of severe osteoarthritis hips
false medial acetabular wall
forms of biological failure
A) aseptic loosening
B) septic loosening
C) stress protection
Hayes found an higer rate of luxation in luxoid hips treated with THR. T or F
F. acetabular depth ratio associated.
Vancouver classification of femur following THR
-Ag and Al: greater and lesser throcanter
-B1,2,3: fractures involving prosthesis (b1 stable, others unstable)
-C: distal to prosthesis
pulmonary emboli has similar rates in press fit and Zurich THR. T or F
F. 82% cemented press fit (Liska); 0/11 Zurich
