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By Kate Livingston
Advisors: Dr. Ron Montgomery and Dr. Kristin Kry
7 year old, Female spayed American Staffordshire Terrier who
presented to the Auburn Orthopedics service on July 30th,
2014
Rescued in November of 2013 after she was abandoned by her
previous owners
She was extremely malnourished and heartworm positive (last
treatment in June)
July 1st- The owner noticed an acute non-weight bearing
lameness on the left hind limb after Baely returned from
running in the woods with their Beagle
On presentation at the referring veterinarian, Baely was toe
touching in her left pelvic limb
The rDVM originally thought her hip was injured but then
palpated a medially luxating patella on the left hind limb
They opted to attempt to medically manage the lameness with
Tramadol and piroxicam
Physical exam:
o Temperature: 100.0 Fº
o Pulse: 84 beats per minute
o Respiration: 20 breaths per minute
o Weight: 57 lbs
o Obvious left hind limb lameness
o Mildly dry and scaly skin with a spot of alopecia
on the left distal hock
o No other abnormalities were noted
Appropriate conformation
At rest:
o non-weight bearing in left hind limb
At a walk:
o Grade 4/4 lameness of left hind limb
Lameness grading scale
Grade Description
1 Inconsistent lameness when walking that is hard to
observe
2 Mild consistent lameness easily observed when
walking
3 Occasionally carrying the limb, loading the limb
4 Carrying the limb, non-weight bearing
Cranial cruciate ligament
rupture or tear
Meniscal tear
Patellar luxation
Trauma to the limb (fracture,
luxation, subluxation)
Limb palpation with flexion and extension of joints
and effusion of the stifle
1. Patella
2. Femur
3. Straight patellar ligament
4. Tibial tuberosity
5. Medially luxating patella
6. Laterally luxating patella
Grade 3/4 medially luxating patella
Grade Description
1 Patella is in trochlear groove, but can be luxated
out of the groove manually. When released, the
patella returns to the trochlear groove.
2 Patella is found in or out of the groove and can
be manipulated easily in or out of the groove.
3 Patella is found out of the groove and can be
reduced manually but reluxates when released.
4 Patella is found out of the groove and cannot be
manually reduced.
Congenital
No history of trauma
Often bilateral
Juvenile or adult at
presentation
Chronic onset
Not painful
Occasional leg carrying
lameness without yelping or
pain association
Traumatic
Rare
Traumatic activity
Adults
Acute onset
Painful for days to weeks
after onset
Coxa Valga (Knock-kneed), +/- anteversion of the femoral head
causes lateral patellar luxation
Coxa Vara (bow-legged), +/- retroversion of the femoral head
causes medial patellar luxation
If patellar luxation occurs in a dog < 6 months of age, the
severity of the grade can progress. Surgery should be performed
as soon as possible so that limb deformities do not occur as the
dog continues grow.
Patellar luxation can cause altered muscle pull on the limbs and
cause permanent bony changes in 2-4 weeks
Medial and Lateral patellar luxation can occur
Medial luxation of the patella is the most common in all breeds
of dogs with toy breeds representing the highest percentage
Giant breed dogs have a greater chance of lateral patellar than
other breeds
Toy Breeds
Medial
98%
Lateral
2%
Medium Breeds
Medial
90%
Lateral
10%Large Breeds
Medial
80%
Lateral
20%
Giant Breeds
Medial
67%
Lateral
33%
Because Baely had no previous history of a medially luxating patella
prior to the onset of lameness, her luxation is most likely due to a
traumatic event
It is important to also test dogs for presence of a cranial drawer sign
or a positive tibial thrust to make sure the cranial cruciate ligament is
not also torn because it was a traumatic event
The medial meniscus also has the potential to tear and can cause
lameness in some dogs. There is not a good physical diagnostic tool
that can determine a torn meniscus. A meniscal click can often be
found but typically in only 50% of dogs with a meniscal tear
Arthroscopy can be performed prior to surgery to check for a
meniscal tear and intact CCL.
Complete Blood Count:
o Within normal limits
Chemistry:
o No remarkable findings
Thoracic Radiographs:
o No contraindication to anesthesia
Abrasion trochleoplasty
Wedge recession of trochlea
Block recession of trochlea
Lateral imbrication
Medial desmotomy
Tibial crest transposition
Derotational suture
Benefits of Arthroscopy
o Minimally invasive
o Good visualization of the joint and structures within
o Allows visualization of CCL and meniscus prior to surgery in order to
plan surgery appropriately
o Can show signs of inflammation and degeneration that might not be
visualized on radiographs
o Baely had mild synovitis present but an intact CCL and meniscus
Baely’s trochlear groove showed some degenerative changes as
well as an ulcerated lesion on the medial side of the groove
indicative of a traumatic event
In a block recession, a block of the trochlea is removed in
order to deepen the groove and allow the patella to sit deeper
into the groove and thus inhibit luxation
A block recession is often better than a wedge recession
because it allows the patella to sit further into the groove and is
reportedly more beneficial for large breeds
Saw and drill
Osteotome
Hall Air Drill
The retinaculum and joint capsule on the opposite side of the direction of the patellar luxation become stretched, and when the patella is reduced redundant tissue is often present
The redundant tissue causes a lack of tension on the patella and therefore the patella luxates more easily
The lateral imbrication is used to reduce the amount of redundant soft tissue and to put more tension on the patella laterally.
Due to the contraction of soft tissues medially that are preventing reduction of the patella and the severity of the grade of the luxation, a medial desmotomy was needed in order to relieve some of the tension on the medial aspect of the leg
The incision is made through the medial fascia and fibrous and synovial layers and extends from the tibial plateau to separate the vastus medialis and the caudal belly of the sartorius
The medial desmotomy will allow the patella to be reduced back into the trochlear groove easily and will also release some of the tension that might be pulling the patella medially
A lateral derotational suture can be used in
repair of cranial cruciate ligament rupture
or can be used to decrease internal rotation
of the stifle joint in cases of medial patellar
luxation
A 60 pound monofilament suture was used
for Baely and was placed around the lateral
fabella and between the joint capsule and
patellar ligament and through the tibial
crest and tied laterally
Recovery from surgery was uneventful
She did not appear overtly painful and recovered from
anesthesia smoothly
Medication:
o Codeine sulfate (60mg): 1 tablet PO every six hours as needed for pain
o Carprofen (100mg) chewable tablet: ½ tablet PO every 12 hours for 5
days for inflammation
She was discharged two days later on August 1st
Continue Carprofen until gone (5 days) and give Codeine every 6 hours as needed for pain
Monitor incision site for swelling, redness, heat, and discharge
Ice pack incision for 5 minutes twice daily after exercise for the first 3 days, then warm compress for 5 minutes twice daily the next 3 days
Beginning 3-5 days after surgery, walk the dog as much as possible for the next 3-4 weeks post surgery
Short, slow, leash walks at least twice daily are encouraged initially in order to attempt to get Baely to start putting some weight on her left hind limb
Massage and range of motion exercises can also be performed
Do not allow any strenuous or excessive activity or rough play
Her physical activity can gradually be increased and eventually consist of unrestricted activity in a fenced in yard
Today Baely is doing very well and is back to her normal
activities
The owner said it took her about 6 weeks to make a full
recovery
Client communication is very important for surgical outcomes
of orthopedic cases
Don’t forget the importance of documenting the presence of
DJD prior to surgery and telling the owners!
http://www.enpevet.de/lexicon/ShowArticle.aspx?articleid=41057&language=en&noop=
http://www.vetmedclinic.com/?p=79
http://dfwvetsurgeons.com/library/medial-patellar-luxation-mpl/
http://www.canadianveterinarians.net/programs/annual-convention-abstracts-
2011/html/companion/companion_beale_02-repairing_medial_patellar_luxation.html
http://veterinarycalendar.dvm360.com/juvenile-bone-and-joint-diseases-large-dogs-rear-legs-and-
small-dogs-proceedings?rel=canonical
http://www.pt.ntu.edu.tw/hmchai/hGlossary/Retroversion.htm
http://www.vetnext.com/search.php?s=onderwerp&id=73381075388%20311
https://www.acvs.org/small-animal/patellar-luxations
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0097329
http://www.bearscampnewfs.com/health/Waltham%20Center/Rational%20Treatment%20Optio
ns%20for%20Medial%20Patellar%20Luxation.pdf
http://www.gvma.net/files/public/Harper_Patellar_luxation.pdf
http://www.onlineveterinaryanatomy.net/sites/default/files/original_media/presentation/asset_82
90_Anatomy%20of%20the%20Canine%20Hindlimb.pdf
Family
David
Friends
Liz Hodson
Katie Smith
Dr. Montgomery
Dr. Kry
Dr. Matz
Class of 2015
THANK YOU!!