Septic Arthritis and Tenosynovitis

How can neonates get septic arthritis?

Hematogenous, polyarticular, physitis, failure of passive transfer

What should you always do with septic arthritic neonates?

Blood culture

What is the pathogenesis of septic arthritis?

Pathogenesis is very complex and if not treated will lead to chronic severe synovitis with matrix destruction and OA

What does the degree of joint destruction depend on?

Chronicity

Bacterial virulence and number

Preexisting joint disease

Host age and health

Degree of inflammation

What are the C/S of septic arthritis?

Variable degree of lameness

Synovial effusion

Soft tissue swelling and edema

Heat

Pain

Fever

T/F septic synovial structures are always an emergency and require immediate attention?

True

Where should you do a joint tap during a laceration?

As far away from the laceration as possible

How do you diagnose septic arthritis?

History, C/S, PE, US, Rads

Arthrocentesis

Extend joint and inject fluid to see if it escapes

Why are horses so susceptible to septic arthritis and tenosynovitis?

The limbs have poor muscle and soft tissue covering with reduced vascular supply

Extension from adjacent infection is common

T/F iatrogenic septic arthritis and tenosynovitis is common?

True

What is a common way for foals to get septic arthritis and tenosynovitis?

Hematogenous spread

What is a consequence to synovial membranes producing a strong inflammatory response?

Can lead to significant cartilage damage and chronic lameness

What improves the prognosis for septic arthritis and tenosynovitis?

Treatment within the first 24 hours

What is S type foal SA?

Synovial infection resulting in joint swelling, may be accompanied by periarticular soft tissue swelling. Often more than one joint involved and occurs in first 2 weeks of life

What are the joints that most often get S type Foal SA?

Carpal joints

Stifle

Hock

What is E type Foal SA infection?

Infection of the joint and adjacent epiphysis and can involve one ore more joints. Usually seen in foalls 3-4 weeks of age

What are the most common sites for type E SA infection in foals?

Medial and lateral femoral condyles

Tibial tarsal condyles

Lateral styloid process of the distal radius and distal tibia and patella

What is a type P foal SA infection?

Infection restricted to physis, but can have nonseptic effusion of adjacent joint. Septic effusion can occur rarely

Usually between 1-12 weeks old

What sites most often get type P SA infection in foals?

Distal radius and tibia

Metacarpal and metatarsal physes

What is a T type SA infection in foals?

Infection of the small cuboidal bones of the carpus and tarsus with spread of the infection into the joints

What are the most common types of SA in foals?

E and S

What do owners think the lameness is in foals?

From trauma, need to ensure it is not SA

What joint most often gets SA in foals?

Tarsus

What are sources of bacteremia you should evaluate in a SA foal?

FPT, umbilicus, respiratory system, GI system, and placenta

What is the cornerstorn of SA treatment?

Antibiotics and lavage

What is a significant source of pain in SA?

Nerve endings in joint capsule

What is the most consistent C/S of SA?

Effusion

Why is the synovium a great place for bacteria to seeed?

Large surface area and very vascular

What type of bacteria often cause SA?

Gram negative

How do you treat SA/osteomyelitis in foals/

IV antibiotics like amikacin or 3rd gen cephalosporins

Can take up to 2 months if osteomyelitis is happening

What factors affect prognosis of SA in foals?

Polyarticular or not

Concurrent osteomyelitis

What should you use for pain for a SA foal?

NSAIDs and fentanyl

T/F you want bactericidal drugs for SA?

True

What is the con of needle lavage in SA?

Will not remove fibrin which houses bacteria

How can you confirm wound communication with a joint?

Joint distension after a arthrocentesis

What are normal colors of synovial fluid?

Yellow to dark orange or red

What can indicate infected synovial fluids?

Nucleated cell count >5000 uL

TP greater than 2.0 g/dL

Lactate >4.0 mmol

Why is cytology of synovial fluid so important?

If normal there will be small lymphocytes and macrophages

If neutrophils are present in >50% there is infection

What do you need to culture synovial fluid with?

Enriched broth because it will still come back negative even though you know it is infected

What happens to synovial fluid as it gets more and more infected?

It gets more water like

What is different about synovial fluid analysis in horses that had steroid injections?

TNC will be lower and you will need to use % of neutrophils and intracellular bacteria to diagnose sepsis

How do you treat septic arthritis in adults?

Aggressive therapy ASAP

Arthroscopy is gold standard for lavage. If severe might need arthrotomy to drain post op

Lavage for days

IV antibiotics with penicillin and gentamicin then oral for 14-21 days

Regional limb perfusion with amikacin

Supportive care with IV fluids, rest, bandages, bedding to prevent contralateral limb laminitis

What can you use to stun a foal and allow for lavage?

Butorphanol. DO NOT USE ALPHA 2s

How do you know if your treatment of SA is successful?

If the horse is able to walk sound without NSAIDs 8-10 days post op

Can also look at neutrophils in synovial fluid

How do you do a regional limb perfusion for SA treatment?

Use amikacin and maybe a beta-lactam. Add lidocaine to help horse stay still and not be painful

Should use concentration dependent antibiotics

Do 3 treatments every 24-48 hours

Use 1/3 the systemic dose

What increases your intraarticular antibiotic dose?

Biofilms or fibrin

What can increase the survival rate of a intraarticular antibiotic to treat SA?

Arthroscopy

What decreases survival of SA?

Delay in treatment, increase in TP, positive culture, S. aureus, More than one arthroscopy, osteomyelitis, bone or tendon involvement

What intraarticular antibiotics are most cytotoxic?

Aminoglycosides and doxy but we use amikacin anyway

What vessel is best to do a regional limb perfusion?

Proximal vessel for less pain and thrombophlebitis but any vessel can work

What is the main reason for failure of a regional limb perfusion?

Movement, as tourniquet is less effective

T/F adding lidocaine to a regional limb perfusion increases efficacy?

True

What can you do if you need additional pain control for SA?

Fentanyl patch, lidocaine, butorphanol, or ketamine CRI

Epidural

Morphine IM

Tri fusion

Penta fusion

Acetaminophen

What is the prognosis of SA?

Most will survive but only 50% of them will be athletic still