By Kate Livingston Advisors: Dr. Ron Montgomery and Dr...

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!!