Exam 1 Flashcards
Anatomy of the Cranial Cruciate Ligament
Originates from the medial aspect of the lateral condyle, courses cranially and medially and attaches on the craniomedial aspect of the cranial plateau
Made up of two pieces
-Craniomedial band - taut in both flexion and extension
-Caudolateral part - taut only in extension
Functions of the Cranial Cruciate Ligament
Functions to Prevent:
- Cranial drawer
- Internal rotation
- Hyper-extension
Cranial Cruciate Ligament Basic Presentations
Insidious onset, mild but chronic lameness
Insidious onset, progressively worsening lameness
Acute onset, improved then worsening lameness
Acute onset, progressive with an acute worsening of lameness
Acute onset, non-weight bearing
Unable to use back end
Cranial Cruciate Ligament Presentation - Insidious Onset, Mild but Chronic Lameness
Presented by discriminating owner Younger dogs Active or performance Worse after exercise Early partial tears NO cranial drawer Exhibit pain while checking for drawer Radiographs WNL or mild effusion Definitive diagnosis requires MRI or arthrotomy
Cranial Cruciate Ligament Presentation - Insidious Onset, Progressively Worsening Lameness
Middle age, overweight, often female
No specific incidence of injury
Worse after exercise
Will sit sideways, affected leg extended - very characteristic of cruciate damage
Muscle atrophy
Thickening on inside of stifle - medial buttress
Will have drawer, especially in flexion
-Drawer in flexion means that only the craniomedial part is ruptured because in extension the caudolateral part is taut
Radiographic Signs of Cranial Cruciate Injury
Joint effusion
Osteoarthritis - osteophytes
Cranial Cruciate Ligament Presentation - Acute Onset, Improved then Worsening Lameness
Most common history Initial incident Better in days, then worse in 3-4 weeks Usually see 3-4 months after Worse after exercise, stiff after rest Hesitate to sit down, sits over to one site Medial thickening Moderate muscle atrophy Cranial drawer
Cranial Cruciate Ligament Presentation - Progressive with an Acute Worsening of Lameness
An initial episode with partial to complete resolution of signs
3-5 months thereafter, a second injury occurs
Often non-weight bearing
Muscle atrophy
Medial thickening
Cranial drawer
Crepitation (meniscal click)
Cranial Cruciate Ligament Presentation - Acute Onset, Non-Weight Bearing
Athletic dog History of injury during strenuous activity Usually non-weight bearing Swollen knee Effusion Dramatic cranial drawer No medial thickening
Cranial Cruciate Ligament Presentation - Unable to Use Back End
Most difficult situation Condition often confused with neurologic condition or hip dysplasia Trouble getting up Can ambulate if assisted Unsteady gait Can stumble Patellar reflexes are exaggerated Cranial drawer PRESENT May or may not have medial thickening Varying degree of osteoarthritis Very difficult cases Watch for endocrinopathies
What are the two tests that you do in the exam room to diagnose a cranial cruciate ligament rupture?
Cranial drawer test
Tibial thrust test
Cranial Drawer Test
Index finger on patella, thumb on fabella
Index finger on tibial tuberosity, thumb on fibula
Push caudal, then cranial
Perform through a variety of degrees of flexion
Look for pain response
Any drawer is abnormal
Tibial Thrust Test
Grasp stifle and place index finger from patella to tibial tuberosity across straight patellar tendon
Grasp tarsus and flex
Look for cranial motion of tibial tuberosity
Lateral Prosthesis Cranial Cruciate Ligament Repair
One of the most common procedures done
Extracapsular
A piece of nylon is run from the femoral fabellar ligament through the holes in the tibial tuberosity on the outside of the joint and tightened down using crimp clamp techniques
It is at the same angle on the outside of the joint as the cruciate is on the inside so it takes up the function of the cruciate
Tibial Plateau Leveling Osteotomy for Cranial Cruciate Ligament Repair
Compressive forces on the tibia are generated during normal locomotion
Because the tibial plateau is sloped caudally, shear creates a “cranial tibial thrust”
Cranial tibial thrust is opposed by the CCL in the normal knee
When the CCL tears, unrestrained tibial thrust results in an unstable knee during locomotion
The central principle of TPLO is an attempt to neutralize cranial tibial thrust in the CCL deficient knee
Neutralization of cranial tibial thrust is accomplished by flattening the tibial plateau
Preoperative planning
-Straight and lateral AP views
-Include distal femur and tarsus
-Check for limb alignment
-Measure preoperative slope of the tibial plateau
Medial approach to the stifle is recommended, although lateral is acceptable
Joint is explored, CCL remnants excised, and menisci examined
The tibial plateau is leveled
A patented oscillating saw and biradial saw blade is used to created the osteotomy in the proximal tibia
A patented jig is used to aid limb alignment during osteotomy and stabilize the proposed fracture in one plane during rotation
The tibial plateau is rotated a predetermined amount based on the preoperative tibial plateau slope
An IM pin is used as a handle for rotation, and the osteotomy is held in place temporarily with one or two K wires
The osteotomy is repaired with a patented plate and screws
Tibial torsion is corrected if present
Bending the distal jig pin will axially rotate the tibia distal to the osteotomy to eliminate internal torsion
Medial Meniscus in Cranial Cruciate Ligament Injury
Meniscal release or excision of a tear is performed in every surgical case
If the caudal horn of the medial meniscus is torn it comes out
If the meniscus is normal you do a meniscal release
Grade I Medially Luxating Patella
Patella can be manually luxated but spontaneously reduces
No clinical signs
Grade II Medially Luxating Patella
Patella is most often reduced (in normal position), can be manually luxated and will stay luxated
Intermittent non-weight bearing lameness followed by periods of normalcy
Grade III Medially Luxating Patella
Patella is luxated, but can be manually reduced
Chronic lameness
Grade IV Medially Luxating Patella
Patella is luxated and cannot be manually reduced
Chronic severe lameness with deformity of caudal limbs
Medially Luxating Patella Goals of Surgical Correction
Re-establish pull of the quadriceps so that the patella overlies a trochlear groove of sufficient depth
Simply reducing the patella and suturing into place results in a high rate of failure
Grade I Medially Luxating Patella Surgical Correction
None
Grade II Medially Luxating Patella Surgical Correction
Wedge recession
Tibial tuberosity transposition
Lateral imbrication
Grade III Medially Luxating Patella Surgical Correction
Wedge recession
Tibial tuberosity transposition
Medial release of sartorius muslce
Lateral imbrication
Grade IV Medially Luxating Patella Surgical Correction
Usually requires corrective osteotomies of distal femur
Anatomy of the Physis
From Epiphysis to Metaphysis Zone of Resting Cartilage Zone of Proliferation Zone of Maturation Zone of Hypertrophy Zone of Calcification
What side of the physis is the resting cell layer on?
Epiphyseal side
Salter Type I Fractures
Physis
Usually stable except shearing forces
Best prognosis
Salter Type II Fractures
Physis, Metaphysis
Essentially the same prognosis as Salter I
Salter Type III Fractures
Physis, Epiphysis
Articular!
Salter Type IV
Epiphysis, Physis, Metaphysis
Same concerns as Salter Type III
Salter Type V
Crushing
Is not fractured, can not see radiographically
Bone growth arrested
Commonly Seen Salter Fractures
Type I -Proximal Femur - Slipped Capital Physis Type II -Distal Femoral Physis -Proximal Tibial Physis -Distal Tibial Physis Proximal Humeral Physis Type IV -Humeral Condylar Fracture
Treatment of Articular Fractures
INTERNAL FIXATION -Prompt action -Perfect anatomic reduction -Rigid fixation -Gentle handling of soft tissue -Postoperative physical therapy Articular fractures involve the joint so we need to maintain that joint, can't immobilize it for a long time because need to keep the joint healthy
Salter Fracture Repair
Salter fractures often use small pins because they’re inherently stable, the pins are working in shear
Radius Curvus
Salter Type V
Premature closure of the distal ulnar physis
Continued growth of the radius
Cranial bowing, lateral deviation, supination
Must recognize it because dogs jump off of things and sometimes they land really hard and they can hurt the distal ulnar physis, if they hurt it bad enough can get Salter V, crushing, where the resting cell layer dies so it can’t get any longer
If you have a dog jump off of something and it is lame and you see a greenstick fracture or nothing you put it in a splint and then tell the owner to come back in three weeks and if you see if they are ever so slightly trying to go into valgus, if they are you do an ulnar ostectomy
Ununited Anconeal Process
Ununited Anconeal Process Commonly occurs in German Shepherds and can be treated with a dynamic ulnar osteotomy
What should you look for if the pelvis is fractured?
If the pelvis is fractured there is at least one other problem.
Could be a ruptured bladder
-Look for bladder margins on X-ray
-Try to palpate the bladder
-If you palpate the bladder and no urine comes out but it gets smaller its leaking into the peritoneum
-Definitively determine if you have a ruptured bladder by putting a 1/2 inch 22G needle into the bladder and sucking up some urine, also take blood, and send those both in for serum chemistries
-If the creatinine from the abdominal fluid comes back higher than the serum creatinine you have a problem, not BUN because it equalizes too fast but creatinine won’t
What is standard of care with an MVA?
Thoracic and abdominal radiographs
If the dog can’t walk there’s a reason and you need to figure out why
Sciatic Nerve
Sciatic Nerve Goes over the sciatic notch, right on the inside of the ilial shaft, then goes down and supplies the semimembranosus, semitendonosus, and biceps, and then the peroneus goes down and supplies the cranial tibial and long digital extensor
Comes from spinal cord segments L6, L7, S1, S2
Vertebral disk location L4-5
Courses over acetabulum
Where do you pinch to check for sciatic nerve function?
Lateral digit
Femoral Nerve
Goes through the intervertebral foramen and comes down the front of the leg in the femoral triangle and supplies the quadriceps and that’s what keeps you off the ground
Spinal cord segments L4, 5
Vertebral location L3-4 disks
Cranial to the pelvis
Where do you pinch to check for femoral nerve function?
Medial digit
What are you looking for when pinching toes to check nerve function?
Recognition of deep pain
Don’t check myotatic reflexes because it the leg is broken the reflex might be intact but can’t respond because its broken
What is the weight bearing segment of the Pelvis?
Femur Head of femur Acetabulum Shaft of ilium Sacroiliac joint Sacrum
How do you fix acetabular fractures?
Open reduction internal fixation (ORIF) - dynamic compression plate (DCP), reconstruction or acetabular plates
Femoral head and neck excision
Requires trochanteric osteotomy
-Exposes acetabulum
-Allows retraction of middle and deep gluteal muscles
-Repaired with tension band
Converts tensile forces of gluteal muscle into compressive forces
How do you fix iliac shaft fractures?
Open reduction internal fixation (ORIF) plate fixation
-Must have 4, preferrable 6 cortexes
Ventral lag screws have been described
Brain Tumor Signalment and History
Signalment -Older dog median age 9 years -Golden, Boxer, Doberman -Older cats, median age 10 years History Dog -Seizure onset in dog over 7 years of age -Also disorientation and personality changes History Cat -Personality changes - vocalization -Locomotor deficits
Types of Disk Disease
Hanson Type I
- Extrusion
- Happens quickly
Hanson Type II
- Protrusion
- Happens over time
- Usually worse prognosis because Type II keeps pushing on the spinal cord and you start losing axons, even if you decompress the axons won’t grow back
Order of Neurologic Loss
First thing that goes is proprioception, A alpha fibers, due to the large size of the fibers
Then motor, A beta fibers
Then superficial pain, sharp pain, A delta fibers
Last thing to go is C fiber pain, achy dull pain
Why is deep pain sensation a prognostic indicator?
It is polysynaptic, diffuse, and bilaterally represented
If you lose deep pain you have a functional transection of the spinal cord
Triage of Intervertebral Disk Disease
How urgent is surgery
Which cases should be operated
What medications should be given
Case presentations divided by:
-Severity
No deep pain, deep pain, motor, walking
-Duration of clinical signs
Conservative vs. surgical treatment prognosis
No deep pain, less than 12 hours - recommend emergency operation
No deep pain, greater than 24 hours - operate when practical
Deep pain present, no motor function - offer emergency operation depending on time if no motor function for over 12 hours, operate when practical for no motor function over 24 hours
Deep pain present, motor function, non-ambulatory - operate when practical
Ambulatory paretic - operate when practical
More worried about one without deep pain than one that still has motor function
Will probably be imaged, find out where you are, probably going to need decompression, laminectomy or hemilaminectomy
Vertebral Fractures
No deep pain perception caudal to the injury, a grave prognosis, euthanasia recommended
The presence of deep pain perception is generally a good prognostic indicator and surgical stabilization recommended
Patellar Reflex
If you have a spinal cord lesion and you tap the patellar ligament its overexaggerated
95% of the UMN are inhibitory so if you push on the spinal cord and damage those you’re disinhibiting
If you push on the neck expect the reflexes in the front and back legs to be exaggerated, then if you push harder they won’t work, then if you push more the patient is dead because they can’t breathe
If you have hyperreflexia to the patellar reflex and its normal in the front leg the lesion is below T3 because T3 is caudal to the thoracic intumescence and above the femoral
If the T3 disk pushes up hard enough it will directly effect the femoral nerve because that’s where the LMNs are, the femoral nerve will be depressed and the sciatic will be exaggerated
Cranial Tibial Reflex
If you push on the sciatic nerve, segments 6 and 7 over the L4-L5 disk if you push on that you have LMN lesion to the sciatic, cranial tibial reflex but the femoral reflex will look a little exaggerated
Caudal Cervical Instability Malformation
Wobbler’s Disease
Malformation or instability of the cervical vertebrae
Like Type II disk disease
Clinical Signs - slow progression of ataxia/paresis that starts in the caudal limbs and progresses to cranial limbs
Can progress to non-ambulatory paresis
Caudal Cervical Instability Malformation Prognosis
Guarded
Often, preventing progression or discontinuing medication is considered a success
Surgery can result in worsening of clinical signs
Recovery can take weeks to months
Cervical Disk Disease
Same as T-L disk disease (Type I) but in the cervical area
Pain is much more common but can be followed by paresis
-Have a lot more space so you’re not pushing on the spinal cord but there are a lot more nerve roots so it really hurts
Slot them
Prognosis is good
The majority of patients are ambulatory and post-surgical care is relatively simple
Cauda Equina Disease
Compression of the nerve roots of the caudae, usually by a disk extrusion
Pain in the lumbar area, especially on lifting the tail
-Very painful because there are lots of nerve roots
Do decompression or if very unstable stabilize them
Generally good prognosis
What nerve root gets pinched with cauda equina disease and what does it supply?
L7 - pudendal nerve and femoral nerve
Bladder and back leg
What is the root of osteochondritis dissicans?
Defect in endochondral ossification
What locations does OCD have a good prognosis?
Caudal humeral head
Tarsus - not as good a humeral head because can’t do arthroscopically
What locations does OCD have a poor prognosis?
Prognosis for all elbow dysplasia cases is guarded as many develop significant osteoarthritis
Panosteitis
Eosinophilic panosteitis, shifting leg lameness Young fast growing large breed dogs Very common Many breeds Often shifting leg lameness Pain on palpation of diaphysis Radiographs show intramedullary sclerosis Treatment with NSAIDs and rest Prognosis is excellent Self limiting, spontaneously resolved
Hip and Elbow Luxations
Always radiograph - when you take radiographs the limb can just be lined up and you can’t see soft tissues, doesn’t mean that the ligaments are all intact so we take stress views, take part of the limb and push on it and see what moves or opens up
Palpation defines injured structures
Reduce luxation
-Use anesthesia
If can’t close reduce must do surgery
Then put in a Ehlmer sling (hip) or Spicca Coaptation Bandage (elbow)
What side does the elbow luxate on?
Always lateral
