Small animal MSK disease 2 Flashcards
Outline the aetiology of carpal hyperextension injuries
- Usually traumatic, associated with fall from height
- Can be degenerative (Collies)
What other injuries may be associated with carpal hyperextension injuries?
Carpal bone fractures esp. when traumatic as well as the rupture of palmar ligaments and fibrocartilage
Describe the diagnosis of carpal hyperextension injuries
- Characteristic seal stance
- Careful palpation
- Radiographic examination including stressed views - establish joints involved and therefore required treatment
Outline the treatment of carpal hyperextension injuries
- Pancarpal arthrodesis most common
- Use bespoke plates, bone graft, removal of all articular cartilage
- Further support until partial arthrodesis occurred
- Splints an support bandages will fail
Explain the difference between luxation and subluxation
- Luxation: cartilage surfaces not in contact at all
- Subluxation: partial contact of cartilage surfaces
What is meant by joint incongruency?
Abnormal shape to bones and cartilage so cartilage does not fit together properly
What are the possible underlying aetiologies of luxations?
Trauma (common), congenital (rare), developmental (frequent)
Describe how traumatic luxations occur
Associated with third degree sprain (except in elbow luxation), joint capsule and other peri-articular structure damage
Outline the consequences of traumatic luxation
- Traumatic arthritis
- Individual ligaments may never heal
- Capsule thickens to assume some function of the supporting ligaments
Outline the treatment of traumatic luxation
- Surgery to restore acceptable function of ligaments
- May require salvage procedures
- Talocrural/tibiotarsal luxation - fixator will restore acceptable function
Explain the cause of congenital luxations
- Malformation of joint, bone or soft tissue leading to abnormal articular surfaces
- Often severe associated bone deformity
Describe the typical presentation of congenital luxations
- May be symmetrical
- Small breed dogs (e.g. cavvie) with shoulder luxations are rarely lame (mechanical rather than painful lameness)
- Congenital elbow luxation in Staffies
Outline the treatment options for congenital luxations
- Conservative: first option, pain releif and weight management
- If unsuccessful, attempt surgical but poor success due to abnormal joint surfaces
- Salvage procedures typically required
What is the prognosis for surgical treatment of congenital luxations?
Guarded
Explain the cause of developmental subluxations/incongruencies
- Common
- Hip/elbow dysplasia
- Incongruency of joints leading to joint effusion and luxation
Describe the typical presentation of developmental subluxation
- Commonly bilaterally symmetrical
- Develop secondary arthritis
Outline the treatment of developmental luxations
- Conservative/medical management of the arthritis
- Salvage surgical procedures
Explain the cause of degenerative luxation
Very common e.g. cranial cruciate ligament degeneration/rupture leading to cranial subluxation of the tibia
Which joints are predisposed to luxation in dogs and cats?
- Hip and tarsus
- Patella (intermittent)
Outline the assessment for luxation in dogs and cats
- Clinical examination (+/- GA): pain,asymmetry
- Laxity (depends on chronicity of disease)
- Orthogonal radiographs of limb, +/- stressed views
When qould thoracic and abdominal radiographs be indicated when investigating joint luxation in cats and dogs?
Where traumatic luxation has occurred
What test would indicate hip luxation on clinical examination of a cat/dog?
- Finger and thumb placed between ischial tuberosity and greater trochanter, hold both HLs
- When HLs extended behind animal, luxated limb will be shorter due to dorsal luxation
Explain why laxity may not always be a good indicator of joint luxation
- Depends on chronicity of condition
- With time, partiarticular fibrosis and muscle contraction can stabilise the joint
Outline the principles of repair of acquired/traumatic luxations
- Reduce joint into normal anatomical alignment, maintain reduction while capsule and other soft tissues heal
- Re-attach bone if avulsion present
- May require prosthetic ligament
- Post-op support as for sprains
What are the 3 main stabilisers of the hip?
- Round ligament
- Joint capsule
- Acetabular rim
List the options for the management of hip luxation
- Closed reduction
- Open reduction and stabilisation such as:
- Salvage procedures
- Transarticular pin
- Rectus femoris or ilio-femoral suture for craniodorsal luxation
- Hip toggle
Describe closed reduction of hip luxation
- Manipulate hip back into acetabulum without surgery within 1 day of luxation
- Always readiograph after
- Care re/ soft tissue injuries and re-luxation
- May also require Ehmer sling
What is the success rate for closed reduction of hip luxation?
50%, higher in dogs than cats
Describe open reduction and stabilisation of hip luxation and give success rare
- Always includes soft tissue repair/imbrication
- E.g. transarticular pin, toggle, rectus femoris or ilio-femoral suture
- 75-85% success
What salvage procedures may be used for hip luxation?
Replacementof excision
Discuss the use of transarticular pins for hip luxation
- Most suitable for cats/small dogs
- Gives reasonable function but limited adduction
- Causes arthritis
- If incongruent may damage articular surface
- Requires 2nd procedure 3 weeks later to remove pin
Describe the use of rectus femoris or ilio-femoral suture for craniodorsal hip luxation
- Suture placed through tunnel in base of greater trochanter and either: origin of rectus femoris, or hole made in ventral aspect of ilium
- Suture tightened with hip slightly internally rotated
- May cause slight internal rotation of paw (resolves with suture absorption)
Discuss the use of hip toggles for canine hip luxation
- Challenging
- Medium to large dogs best
- Can cause articular damage if hip not congruent
- Very stable, functional joint if correct
- Braided multifilament suture use so some risk of infection
Outline the method for the hip toggle in dogs
- Drill hole through acetabular notch
- Then another from origin of teres ligament, through femoral neck to base of trochanter
- Then place suture through hole, as pushed through pull on loop, toggle comes into right angle to hole
- Tightening holds head in acetabulum
Outline the approach to traumatic elbow luxation
- Treat Asap, always GA, pre-op radiographs including thorax
- Closed or open reduction can be used
- Check collateral ligaments
- Post-op radiographs required
Outline the approach to congenital elbow luxation
- Can be treated conservatively if dog is coping
- Surgery can be beneficial, but residual lameness common so little benefit over conservative
Outline the general approach to acquired luxations
- Reconstruct supporting structures if possible
- Support repair
- Physio improves recovery
- DJD inevitable, warn owner
Outline the general approach to subluxations
- very common
- medically manage if milk
- Salvage surgery if not coping
Outline the general approach to congenital luxations
- Very rare
- Poorer prognosis
- Grossly dysplastic joint and better left alone
What diagnostic techniques can be used for the evaluation of acutely traumatised joints?
- Careful physical examination
- Manipulation under GA
- Radiography
- Ultrasound
- arthroscopy
- CT
- MRI
- Need to look for concurrent injuries
Outline the use of ultrasonography for the evaluation of acutely traumatised joints
- Damage to tendons, rarely for ligaments
- Linear scanner
- Bicipital, gastrocnemius and flexor tendons in particular
Outline the use of arthroscopy for the evaluation of acutely traumatised joints
- Examine intra-articular ligaments e.g. cruciates
- And those withinn the joint capsule such as glenohumeral ligaments of the shoulder
Outline the use of CT for the evaluation of acutely traumatise joints
- Limited ability to examine soft tissue structures
- Good for demonstration of tendon sheath effusions and tendon mineralisation e.g. around shoulder joint (mineralisation of suprascapularis tendon or infraspinatus)
Outline the use of MRI in the evaluation of acutely traumatised joints
- Good for soft tissues
- Best modality for tendons and ligaments
List the different types of non-inflammatory joint disease
- DJD/OA: instability, trauma or developmental disease
- Coagulopathic joint disease
List the different types of inflammatory joint disease
- Septic arthritis
- Non-bacterial: rickettsia, viral, protozoal
- Sterile: IMPA
- Neoplastic arthritis
- Crystal induced arthritis
Explain how tick borne diseases lead to arthritis
Immune mediated responses that cause polyarthritis
What is the main type of neoplastic arthritis?
Synovial cell sarcomas
What tumours may cause neoplastic arthritis?
- Synovial cell sarcomas
- Fibrosarcomas
- Haemangiosarcomas
- Osteosarcomas
Describe the common presentation for neoplastic arthritis
- Dogs (rare in cats, large animals)
- Large joints of limb usually (e.g. stifle)
- lameness, joint effusion, soft tissue swelling, lytic areas of bone destruction on radiograph both sides of joint
In which species does true gout occur?
Those without uricase enzyme: humans, birds, reptiles
How does gout occur in reptiles?
- Production of uric acid normal, secrete as urates in proximal renal tubules
- Damage to kidney raises uric acid in blood
- Deposits in various parts of body incl. kidney, pericardial space, joints
Outline crystal induced arthritis in dogs
- White, peri-articular deposits lead to inflammatory reaction
- Rare in dogs
- Peri-articular synovial deposits of calicum pyrophosphate, or Ca phosphate
- Single or multiple can be affected
Outline the aetiology of IMPA
- Usually type III hypersensitivity reaction
- Immune complex deposition in synovial basement membrane, complement cascade activation
- Recruitment of inflammatory cells
- Leads to release of nitric oxide, free radicals, proteases, leading to tissue damage
Give examples of erosive immune mediated polyarthritis
- Idiopathic erosive polyarthritis
- Rheumatoid arthritis
- Semi-erosive polyarthritis of greyhounds
- Periosteal proliferative polyarthritis in cats (rare)
Describe type I non-erosive IMPA
Idiopathic IMPA, most common
Describe type II non-erosive IMPA
- Associted with infection remote from joint (25% of cases)
- Not septic, is an immune reaction
Describe type III non-erosive IMPA
- Associated with GI disease (15% of cases)
- Immune complexes deposited in joint
Describe type IV on-erosive IMPA
Associated with neoplastic disease i.e. paraneoplastic syndrome (rare)
Describe the involvement of SLE in joint disease
- Multisystemic immune mediated disease, rare
- Joint disease + glomerular disease, or joint disease + skin lesions
- IMHA +/- thrombocytopaenia
- Combination of clinical signs increases potential for multisystemic disease
List some unusual syndromes of non-erosive immune mediated polyarthritis
- Polyarthritis/meningitis syndrome
- Polyarthritis/polymyositis syndrome
- Breed associated non-erosive IMPA
- Familial Shar-Pei fever
- Drug induce IMPA
List the breeds that are associated with breed related non-erosive IMPA
- Weimaraner
- Boxer
- Akita
- Bernese MD
- GSD
- Spaniels
- Beagles
Outline drug induced IMPA
- Immune complex deposition as a result of drug-antibody interaction
- Reported with sulohonamides esp in Doberman
- Post live Calicivirus vaccines in cats
Outline the aetiology of septic arthritis in small animals
- trauma
- Post-surgery
- Intra-articualr injection
- Idiopathic
What may lead to idiopathic septic arthritis?
Underlying OA in dogs
What may cause septic arthritis in multiple joints of adult small animals?
- Haematogenous spread of infeciton in debilitated/immunosuppressed animals
- Non-bacterial causes e.g. Rickettsia, Mycoplasma, fugnal , viral, protozoal (rare)
What clinical signs may be seen in cats with septic arthritis as a result of Calcivirus?
- Inflammatory joint disease
- Pyrexia
- Other flu symptoms
What may lead to septic arthritis in large animal neonates?
- Failure of passive transfer of immunity
- Umbilical infection
- Haematogenous spread of infection
- Osteomyelitis
Describe the signalment for IMPA
- Larger breed dogs <6yrs old
- (Also seen in smaller breeds and mixed beedds)
- More dogs than cats
What would a shifting lameness that may wax and wane be suggestive of?
Immune mediated disease
Describe the lameness commonly seen in IMPA
Often look stiff rather than lame, more than one limb affected
In a case of arthritis in a small animal, what should be included in the physical examination?
- Assess for pyrexia
- Number of limbs/joints affected
- Palpation to assess heat, swelling, ROM, pain, joint affected
- Neck/muscle pain
- Lymph nodes assessed
When performing arthrocentesis for the diagnosis of an inflammatory arthritis in small animals, what parameters of the synovial fluid needs to be assessed?
- Colour
- Total and differential white cell counts
- Cell morphology
- Culture and sensitivity
When would radiography be indicated in the work up for a case of inflammatory arthritis?
- If joint palpation reveals crepitus, instability, poor ROM, deformity
- If there is poor response to treatment
Compare the radiographic findings expected for erosive vs. non-erosive IMPA
- Erosive: subchondral defects, collapsed joint spaces, proliferation and calcification of periarticular soft tissue
- Non-erosive: joint effusion likely only finding
When might a diagnosis of erosive IMPA be missed on radiography?
If radiographs taken too early in course of disease - if not responding well to treatment, may be appropriate to repeat radiographs of multiple joints
What additional imaging modalities may be required in the investigation of IMPA and why?
- If suspicious of type II, III or IV IMPA or multi-systemic immune mediated disease
- Thoracic radiographs: mets of neoplastic disease, endocarditis
- Abdominal ultrasound
- Echocardiography
When might contrast studies be useful in the investigation of inflammatory joint disease?
- Septic arthritis
- Especially in horse
- Look for communication between tracts/sinuses and a joint
- May be able to identify a foreign body
Outline the laboratory tests that may be used in the investigation of inflammatory joint disease
- Haematology: inflammatory leukogram? Anaemia of chronic disease? IMHA?
- Biochem: changes consistent with systemic disease
- Urinalysis: proteinuria/evidence of glomerulonephropathy
- Serology: ANA and rheumatoid factor (non-specific in dogs)
- Histopathology: tissue biopsy for unusual syndrome
Compare the findings in haematology and biochemistry for IMPA vs non-inflammatory joint disease
- More likely to find changes with IMPA
- Leukocytosis
- Hyperglobulinaemia
- Mild hypoalbuminaemia
What are the key aspects of investigation that may aid the identification of IMPA?
- Full flexion of carpi and squeezing to assess pain response
- Subtle enlargement of LNs
- Aspiration of multiple joints
- Changes in >1 joint, no bacteria on cytology or culture
Outline the key aspects of the treatment of septic arthritis in small animals
- Must be fast and aggressive
- Systemic and intra-articular antibiotics
- Joint lavage and drainage to clean joint
- Post-op care important
Discuss the use of lavage in the treatment of septic arthritis in horses, farm animals and small animal cases
- Horses: antibiotics rarely enough, lavage used as minimum
- Farm and severe small animal: lavage possible, often not cost effective in farm animals
Outline the use of arthroscopy in the treatment of septic arthritis
- Direct visualisation of joint
- Removal of fibrin
- Foreign material or articular fractures
- Used in chronic or complicated cases
- Ideally in every equine case
Outline the use of systemic antibiotics in the treatment of septic arthritis in small animals
- Broad spec
- C+S takes time, start before results available
- Amoxyclav common in small animals (penicillin + aminoglycoside in large)
- Start IV/IM admin, switch to oral after 5-7 days, total duration 2-4 weeks min.
Outline the use of local antibiotics in the treatment of septic arthritis in small and large animals
- Intra-synovial admin common in large animals
- High doses with low cost and toxicity achieved
- Gentamycin, amikacin, ceftiofur in horses
- Higher risk of nephrotoxicity in dogs
- PMMA beads useful in chronic/difficult cases
Outline the post-operative care in cases of septic arthritis in small animals
- NSAIDs
- Rest, controlled exercise, physio
- Avoid intra-articular medication, esp. in early stages as will predispose to infection (esp. HAs, PsGAGs, corticosteroids)
Discuss the prognosis for septic arthritis in small animals
- Following systemic antibiotics only: 56% full clinical recovery, 32% persistent mild lameness, 12% poor response (consider lavage)
- Factors affecting outscome: duration, severity, multiple joints affected, concurrent problems (e.g. bacterial endocarditis)
Outline the general treatment of IMPA
- Treat/remove underlying cause or antigenic trigger
- Analgesia while managing primary disease
- Nutritional support where needed
Outline the treatment of type I IMPA
- No underlying cause therefore immunosuppressive treatment
- Single agent e.g pred
- Combination therapy may be needed in refractory cases/side effects e.g. pred + ciclosporin/azathioprine
- Newer single agent therapy e.g. mycophenolate, luflenomide
Outline the monitoring required when treating IMPA
- Clinical sings
- Physical examination findings, owner reports
- Follow up arthrocentesis
- Serum C reactive protein
Evaluate the use of serum C reactive protein for the monitoring of IMPA
- Good surrogate marker for synovial inflammation
- Good correlation with pain scores and joint cellularity
- Objective and non-invasive method to monitor cases
Discuss the prognosis for erosive and non-erosive IMPA
- Good for non-erosive, but may relapse
- Poor for erosive, surgical salvage procedures often required, euthanasia is reasonable alternative
Compare the joints typically affected by IMPA and septic arthritis
- IMPA: smaller distal joints e.g. hocks, carpi, stifle
- Septic: more proximal larger joints e.g. elbow
Compare the synovial fluid analysis of IMPA and septic arthritis
- IMPA: ~300 cells x10^9/l, <95% neutrophils, usually non-degenerate
- Septic: cell count variable but usually very high, most cells are degenerate neutrophils
Outline why septic arthritis may not also be demonstrable by bacteria on smears
Pathology is more to do with sensitive location of bacteria, rather than their number so may be a small load
What may help indicate that blood in synovial fluid following arthrocentesis is as a result of sampling?
- Blood streak in otherwise clear fluid
- Sample starts clear then changes to bloody
Compare the findings on a smear for an iatrogenic/very acute haemoarthrosis vs a long standing one
- Iatrogenic/very acute: platelets present
- Chronic: no platelets (clotted) , increased white cells, erythrophagocytosis, haemosiderin, haematoidin
How can bacteria be distinguished from artefacts on a synovial smear?
- Artefact of fluid not lying flat on slide leading to dotty granular background
- May resemble bacteria, but is pink and irregular vs bacteria which are blue and regular
Explain why neutrophils may be confused with lymphocytes in synovial smears
Slow drying leads to lobes of neutrophilic nucleus becoming folded, so may look similar to lymphocyte
