What is synovial fluid?

What are its functions?

- A dialysate of blood

- Functions as lubrication and nutrition to articular cartilage

What is the chif glycosaminoglycan in the joint?

What does it do?

Hyaluronic acid, which has a high molecular weight

It prevents dilution and provides viscosity

What types of lubrication does the synovial fluid provide?

1) Weeping lubrication - fluid come from cartilage in compression between two apposing surfaces

2) Boosted lubrication - Fluid gets trapped and concentrates on cartilage surface to decrease friction

3) Boundary lubrication - Glycoprotein lubricin binds to articular cartilage with water to provide lubrication at low loads and be displaced at high loads.  The hyaluronan is absorbed into the synovial membrane

How does impaired joint lubrication lead to cartilage degradation and further loss in lubrication?

The lack of lubrication leads to cartilage fibrillation and fissures.  The resulting inflammation depletes matrix proteoglycans, decreasing lubricaton

What are the key points of OA management?

1) There is no cure

2) Once it starts it will progress

3) Radioraphic signs do not correlate with clinical function

4) If you cant treat the primary cause, you can at least manage the inflammation

What are the tenants of medical management?

1. Weight management

2. Exercise moderation

3. Chondroprotectives

4. NSAIDS

What are some examples of chondroprotectives?

Glucosamine

Chondroitin sulfate

Manganese ascorbate

MSM

What are the guidlines for NSAID use?

1) Check for liver or kidney disease first

2) Do not use more than one NSAIDs at a time (wait 4-7 days between switching and 7-10 for aspirin [platelet regeneration])

3) Never use NSAIDs and steroids together

4) Use lowest effective dose

5) Goal is to eventually wean off NSAIDs, check CBC/Chem occasionally

What constitutes an appropriate candidate for a total hip replacement?

1) There aren't problems elsewhere

2) No neurologic disease

3) No neoplasia

4) No cranial cruciate ligament rupture (fix 1st)

5) No infections

When should you perform an arthrodesis?

1) Irreparable fracture of a joint

2) Chronically unstable joint

3) Chonic, severe DJD of any cause

4) Neurologic injury causing partial paralysis of the limb

What are the principles of arthrodesis?

1) Articular cartilage must be removed

2) Bone graft should be used

3) Joint should be fused at an anatomic standing angle

4) Rigid internal (or external) fixation

What is the purpose of a bone graft?

To speed callous formation and decrease implant fatigue via:

1) Ostegenesis

2) Osteoconduction

3) Osteoinduction

4) Osteopromotion

What are the principles of amputation?

1) Gentle tissue handling

2) Careful hemostasis

3) Respect nervous tissue

4) Close dead space

5) Aggresive pain management

What types of analgesia can be used for amputation?

1) IV: Opioids, Lidocaine, Ketamine

2) Epidural: Preservative free morphine, Lidocaine

3) Direct nerve blocks: Epineural Bupivicaine

4) Regional nerve blocks

5) Local anesthetics: Soaker catheters of bupivicaine or lidoderm patches

What are the outcomes of amputation?

1) Good quality of life

2) Limited by other conditions

3) Neoplasia limits life span

What is the treatments for a 3rd degree sprain?

1) Suture torn ligament - imbrication or plication

2) Fascia or tendon graft - acts as a lattice for fibroplasia

3) Prosthetic ligament placement - mimics normal origin and insertion

What are the suture patterns for torn ligaments?

When should conservative management of ligament injuries not be used?

When there is joint instability since the healing scar tissue isn't sufficient to keep the joint stable and the development of 2nd osteoarthritis is likely.

What are the types of muscle-tendon injuries?

1) Muscle contusion: A bruise of hemorrhage and fiber disruption

2) Muscle strain: There's a longitudinal streching and tearing of the muscle belly, muscle-tendon junction, or tendon body

3) Muscle laceration: There's a partial or complete transection of a tendon or muscle

What are the degree's of muscle strains?

1st degree (mild): Minimal lameness, pain, and swelling

2nd degree (moderate): There's obvious lameness, swelling and point pain

3rd degree (severe): There's obvious lameness, with significant swelling, and rapidly progressive pain

How can you determine if a muscle strain is acute or chronic?

If acute: A specific lameness in a regional with pain on palpation and no muscle atrophy

If chonic: A nonspecific lameness in a localized are with little pain, muscle atrophy and osteopenia

What are the principles of treating a muscle-tendon injury?

1) Aim for appostion of muscle or tendon, using minimal gap/tension

2) If too much scar tissue forms, contracture may occur

3) Controled loading of the tendon helps it heal, since the collagen fibrils are better aligned

What is a quadricep muscle contracture?

How should it be treated?

Its a femur fracture that leads to trauma of the quadriceps muscle in young dogs

Its irreversible on its own, so requires surgerical intervention with significant physical therapy.

How should one treat biceps tenosynovitis?

1) Medical management

2) Biceps tendon release (Cut)

3) Biceps tenodesis (Cut and re-attach to humerus)

What is an infrasinatus contracture?

How should it be treated?

A muscle strain occurs to the infraspinatus muscle resulting in permanent contraction and impaired shoulder flexion and rotation

Treat via a partial excision of the tendon

What needs to be evaluated in a complete or partial transection of the tendon?

1) Evaluate the animal while they are standing and weight bearing

2) Be sure to examine the wound for the extent of tendon injury, increasing the wound size if necessary

What suture patterns should be used for the treatment of tendon lacerations?

Same as ligament repair:

- locking loop for flat tendons

- three loop pulley for round tendons

What types of bone tumors are there?

1) Primary bone tumor

2) Metastatic bone tumor

3) Soft tissue tumor

Where do neoplastic cells arise in primary bone tumors?

From within the bone tissue, and need to be determined to be benign or malignant

What are is the common metastasis associated with osteosarcoma?

Metastasis is common and occurs early on. The metastatic sites are typically not noticible on thoracic radiographs.  Thoracic metastasis is much more common than bone metastasis.

Where are the predilection sites for primary bone tumors?

Appendicular skeleton, away from the elbow, towards the knee.  They can be metapyseal or monostotic.

Ex: Prox humerus, distal radius, distal femur, proximal tibia

Where do metastatic bone tumores that invade the bones stem from?

Osteosarcomas or carcinomas from prostate or mammary glands are common.

The lumbar vertebrae and pelvis are common sites

What are example of soft tissue tumors that invade local bone tissue?

What are the effects of these tumors?

Examples: synovial cell sarcomas, histiocytic sarcomas, synovial myxosarcomas

They lead to lysis, proliferation, and soft tissue swelling

What dogs typically present with bone tumors?

Large and giant breed dogs

Greyhounds

Middle to older age (median 7yrs old)

Males are more likely

What can one note on the radiographic evaluation of a bone tumor?

1) Bone lysis

2) Bone proliferation

3) Variable transition zone

4) Codman's triangle: An elevation of the cortex periosteum from the new layer of bone

What are some differential dianoses for bone tumors?

Infection

Multiple myeloma

Synovial cell sarcoma

Metastatic neoplasia

Hypertrophic pulmonary osteopathy

Trauma

Aneurismal bone cysts

What are the principles of bone biopsy?

1) Obtain sample from the radiographic center of tumors

2) Obtain multiple samples

3) Take radiographs after biopsy to confirm biopsy site

What are potential sources of error in biopsy reporting?

1) Poorly fixed or prepared sample

2) Incorrect sampling techinique

3) Non-representing sample

4) Pathologist

5) Incomplete history, patient data or radiographs

What are the treatment options for primary bone tumors?

1) Tumor excision (amputation or limb spare surgery)

2) Amputation and chemotherapy

3) Limb spare surgery and chemotherapy

4) Palliative radiation

5) Palliative analgesia

6) Euthanasia

What are the requirements for limb spare surgery?

1) No concurrent disease

2) No gross pulmonary metastasis

3) Monostotic neoplasia

4) Limited soft tissue involvement

5) Budget

What is the prognosis of an osteosarcoma?

With amputation alone, complications associated with pulmonary metastasis typically kill 90% within one year of diagnosis

The prognosis goes down for younger dogs or if there is an increased alkaline phosphate level