Small animal MSK disease 6 Flashcards
Describe grade 3 canine patellar luxation
Patella usually luxated, can be replaced into trochlea
Describe grade 4 canine patellar luxation
Patella permanently luxated, cannot be replaced into trochlea
Compare the treatment options and prognoses for the different grades of canine patellar luxation
- Grade 1: usually conservative management
- Grade 2:based on presentation, conservative or surgical
- Grade 3 and 4: surgical correction
- Prognosis good for all except grade 4
List the surgical treatment options for canine patellar luxation
- imbrication of soft tissue lateral side of joint
- Deepening of trochlea (wedge or block recession)
- Tibial Tuberosity transposition (TTT)
Explain recession sulcoplasty in the treatment of canine patellar luxation
- Block or wedge recession, reduce size then replace to deepen the trochlea
- Allows quadriceps mechanism to be aligned
- Fixation of wedge not required, held in place by patella
- Block may have better stability on extension
List common hock injuries in small animals
- Ligamentous injuries leading to sub-luxations/luxations
- Shearing injuries
- Osteochondrosis/OCD
- Fracture of tibia or tarsal bones
Describe the fractures commonly seen in greyhounds and their treatment
- Acute non-weight bearing lameness of RH due to running in left landed circle
- Central tarsal bone Fracture (crushed) leads to collapse of hock, leading to fracture of 4th tarsal bone, calcaneous and 5th metatarsal bones
- Surgical repair of fractures (refer) and partial arthrodesis
- Will never race again
What should be performed in all cases of HL lameness and why?
Rectal exam, in order to identify nerve root tumour which may also cause HL lameness
How may lumbosacral disease present
- HL lameness, may look like hip dysplasia
- Pain on palpation, pain when raise tail head, muscle atrophy
Where are osteosarcomas typically located in the HL?
Distal femur, proximal tibia (NB greyhounds get osteosarc in neck of femur)
List the hindlimb disease common in cats
- Hip dysplasia
- Stifle: cruciate disease, patellar luxation (often related)
- Hock: shearing injuries and luxations
- Pad/digital injuries similar to dog
- Fractures and cat bites common
What is the common signalment for collateral ligament injury of the hock in small animals?
RTA, trauma, jumping from height
What is commonly found on physical examination in collateral ligament injury of the hock
- Moderate to severe lameness
- Swelling
- Joint instability including extended and flexed
Outline the treatment of collateral ligament injury of the hock
- Wound management where necessary
- Rigid external coaptation following repair
- Primary ligament repair
- Prosthetic reconstruction
- Transverse screw at origin and insertion of long and short paths of collateral ligament
Describe the signalment for osteochondrosis of the talus in dogs
- Juvenile dogs
- Esp. large and giant breeds
Describe the findings on physical examination in osteochondrosis of the talus in dogs
- Lameness, worse with exercise
- Joint effusion palpable
- Decreased ROM in flexion
- May appear hyperextended
Which radiographic views are used for the diagnosis of osteochodnrosis of the talus in dogs
- Extended plain and craniocaudal, slightly flexed mediolateral, skyline view of tarsus
- Include lateral, flexed lateral and dorsoplantar views of both tarsi
- Additionl: imaging of craniocaudal proximal trochlear ridges, dorsolateral-plantomedial oblique
(DLPMO) view, dorsomedial-plantolateral oblique (DMPLO) view
List the imaging modalities/tests used in the diagnosis of OCD of the talus in dogs
- Radiography
- CT
- Arthrogram
Outline the treatment of OCD of the talus in dogs
- Conservative: can fall away naturally, but painful, medical management in older dogs with severe regenerative changes
- Removal of flap via arthrotomy/arthroscopy
Describe the clinical signs of malleolar fractures in dogs
- Shearing injuries commonly, RTA
- Acute onset HL lameness
- Non-weight bearing
- extensive soft tissue damage and possible bone loss
- Severe hock instability
- Pain, swelling
Describe the treatment of malleolar fractures in dogs
- Initial wound management
- Rigid coaptation following repair (or transarticular ESF) for several weeks
- Surgical: prosthetic repair of collateral ligaments, ESF until granulation tissue covers defect talocrucral/pantarsal arthrodesis if axial part of trochlear ridge involved
- Generally good prognosis
What degree of alignment is required for ESF, open-but-do-not-touch and open reduction fracture repairs?
- ESF: >50%
- Open but do not touch: at least 50% overlap in both planes
- Open reduction: close to 100%
Which factors should be assessed when evaluating fracture repair?
- Alignment
- Rotation
- Implant positioning
- Apposition of fracture edges
Give examples inappropriate fracture fixation
- Implants too small/large
- Too large: risk of fracture at stress riser
- Fail to address forces applied to site
- Too rigid leading to disuse atrophy (esp. with ESF)
Outline the general discharge instructions that should be given to an owner following fracture repair in dogs and cats
- Garden on lead to 3 weeks
- Then lead for 8 weeks
- Cats: restrict to house for 8 weeks
- Cage if very boisterous, or concerns regarding repair itself
- Modifications made to house: e.g. carpets, allow easy access onto furniture to prevent jumping
- Appropriate analgesia
Under what condition may post-operative antibiotics not be required following fracture fixation?
If surgery 45mins-1hr long, perioperative may be enough
Outline the instructions that should be given to an owner regarding dressing management following fracture repair in small animals
- Keep dry: polythene and sock when outside
- Check toes and top of dressing twice daily to ensure toes are warm, no discharge, animal able to feel toe
- Any smell, bring to surgery
- If off colour, bring in with dressing on
Outline the potential complications that may occur with external coaptation
- Casts: pressure sores, loss of digits
- Robert-Jones: pressure sores (esp. over accessory carpal bone and calcaneous), avascular necrosis over digits
In what way do IM pins tend to fail?
- Imperfect construction of column of bone leads to collapse
- Fracture may rotate or collapse
In what way do cerclage wires tend to fail?
Loosen, fail to maintain reduction of fragments, resulting in instability
In what ways do plates tend to fail?
- Loss of trans cortex with cyclical loading leading to plate breaking
- Stress protection of bone leading to atrophy of disuse
- Interface between plate and bone acting as stress riser, common point of failure
In what ways do ESFs tend to fail?
- Pin tract infection
- Fracture through pin tract
- Delayed healing/non-union of fracture if too strong
Identify potential iatrogenic IM pin complications
- IM pin to femur can damage sciatic nerve, esp. in cats
- IM pin may enter joint esp. if retrograde placement of tibial IM pin
What does lucency around a pin tract indicate?
Movement, premature pin loosening
Explain what is meant by fracture disease
- Disease as a result of fracture treatment and immobilisation
- Increased risk with external coaptation, avoid esp. in younger animals
- Includes: joint stiffness, osteoporosis, stress protection, infection, quadriceps contracture
When does quadriceps contracture usually occur?
Femoral fractures in young animals
Describe fracture disease commonly associated with distal femoral fracture
- Muscle atrophy
- Joint stiffness
- Muscle contracture (quadriceps tie-down - quads adhere to femur) leading to stifle hyperextension
- Management extremely difficult
Outline how fracture disease can be prevented
- Avoid external coaptation
- Rigid internal fixation preferable
- Encourage early use of limb, appropriate anaglesia
- Early physio and hydrotherapy
Compare acute and chronic osteomyelitis as a result of fracture
- Acute: soft tissues and associated periosteum, easier to manage with antibiotics
- Chronic: primarily bone infection established around implants
Describe the common presentation for acute osteomyelitis following fracture repair
- ~10 days later
- Not using leg well, some swelling, painful
How long should antibiotics be used for to treat acute osteomyelitis following fracture repair
~3 weeks, infection should resolve within a week
Describe the radiographic changes that may occur with osteomyelitis following fracture repair
- Proliferative changes to the periosteum
- Sclerotic margin to infected area
- Bone lysis, particularly around implants
- Development of involucrum and sequestrum
- Soft tissue swelling
Outline the management of osteomyelitis following fracture repair
- Stabilise bone and control infection first
- Remove necrotic bone and sequestrum
- Appropriate antibiotics, base on swab taken at surgery or from small incision down to bone and swab close to site of infection, not from discharging sinus
- Stabilise fracture, will heal even with infection if no movement
- Once fracture healed, remove implants
What are the main causes of delayed unions and non-unions of fractures in small animals?
- Instability
- Loss of vascular supply
Explain how instability may lead to delayed or non-union of a fracture
- Mild: can have secondary bone healing, takes more time
- If fracture movement exceeds tolerance of granulation tissue, leads to tearing of blood vessels bridging site, preventing sequential deposition of cartilage and eventually bone
- Smaller gap = greater strain
Explain how a loss of vascular supply to a fracture site may occur
- Original trauma
- Extensive surgical approach
- Poor surgical technique
What is the normal blood supply to bone?
- Endosteal origin to inner 2/3rds of cortex
- Periosteal origin to outer 1/3rd of cortex
Describe the blood supply to a fracture
- Normal blood supply disrupted, initially vascular supply for healing comes from surrounding soft tissues e.g. muscles
Outline the management of delayed fracture union
- Patience
- Realistic expectation to owner
- Stage down fixator if think is too rigid to encourage bone loading
- Physiotherapy to encourage weight bearing
Outline the management of fracture non-unions
- Atrophic: non-viable, may require amputation
- Hypertrophic: debride fracture ends, open medullary cavity, compress fracture, apply cancellous bone graft or equivalent
Describe the radiographic appearance of atrophic non-union of fracture repair
Bone tapers to point, and then tapers out again
Describe the radiographic appearance of hypertrophic non-union of fracture repair
- Elephant feet
- Big, splayed, widens at end
Where are non-unions of fractures most common?
- Distal radius and femur
- 2-7yo, between 7-14kg, weight bearing
- Distal radius common in toy breeds
Describe what is meant by malunion
Fracture does not heal in correct alignment, commonly seen in strays where fracture has healed naturally in incorrect plane
Compare the prognoses of common malunions
- Bend in craniocaudal plane: no concern
- Bend in mediolateral plane: often ok depending on degree
- Rotation: poor, esp. in distal femur
Outline the management of revision surgery for fractures
- Aggressive management required
- Debride, stabilise, bone graft
Briefly outline fracture scoring and how it is used
- Fracture given a score to determine lieklihood of uneventful healing
- Higher score means more guarded prognosis
- Performed before fracure repair
What factors should be considered for fracture scoring?
- Patient factors: weight, age, boisterousness/ability to manage cage rest, concurrent illnesses
- Fracture: type, open/closed, associated soft tissue injuries, single/several
- Owner factors: compliance, finances
- Surgeon: ability to manage fracture, correct equipment available
Outline the initial assessment and management of a trauma patient with orthopaedic injuries
- Assess whole patient for life-threatening injuries
- ABC
- Provide analgesia, antibiotic cover (if open wounds) and fluid support
- Decontaminate and prevent further contamination of open wounds
- Support grossly unstable fractures
- Assess for any neurological signs
Outline the further investigation of a trauma patient with orthopaedic injuries
- All animals in RTA need thoracic radiograph
- Drain pneumothorax if present
- Ultrasound of chest
- Check integrity of urinary tract
- FAST ultrasound
- Monitor patient (frequency depending on severity of injuries)
- Fractures etc. of low concern
Describe a Type 1 open fracture
- Small wound, little contamination, treat as closed fracture
- may use appropriate antibiotics, open and clean wound
Describe a Type 2 open fracture
Extensive wound communicating with fracture
Describe a Type 3 open fracture
- Very extensive soft tissue damage and fractured bones seen protruding through skin
- Heavily contaminated
Outline the management of open fractures
- Emergencies
- Sterile water-soluble gel in wound
- Very wide clip
- Copious lavage with warm Hartmann’s best (19G needle, squeeze bag, remove debris)
- Surgical debridement may be needed, maintain as much soft tissue as possible
- Swab for bacterial culture (but often only shows environmental contaminants, infection usually nosocomial)
- IV broad spectrum antibiotics
- Sterile dressing
List the Pavletic 6 basic steps in wound management
- Prevent further wound contamination
- Remove foreign debris and contamination
- Debride dead and dying tissue
- Provide adequate wound drainage
- Provide a viable vascular bed
- Select appropriate method of closure
List the aspects requiring assessment in shearing injuries
- Blood supply
- Damage to deeper tissues, nerves and ligaments
- Bones
- Superficial soft tissues
Describe the assessment of blood supply in shearing injuries
- May be difficult to assess viability to tissue remaining on initial investigation
- In 4-5 days will become more apparent which tissue carries blood supply and is viable
Where do shearing injuries most commonly occur and how are these commonly approached in small animals?
- Most common on medial aspect of hock or radiocarpal joint
- May consider as type III open fracture
Describe delayed primary closure of soft tissue wounds
- Surgical closure pre-granulation, but 3-5 days after wound occurred
- Use when unclear as to what will happen to the wound regarding the viable tissue
Describe secondary wound closure
- Closure of a wound once granulation tissue is present
- 5-10days post wound formation
Describe second intention healing
- Healing by natural processes
- Granulation, contraction and epithelialisation take place
- High cost, lots of time (several weeks)
What is meant by hypermature granulation tissue?
- Fibrous, thick tissue
- Aka chronic
What types of dressing should be used at the debridement stage of wound healing?
- Adherent dressing
- E.g. wet-to-dry
- Dry-to-dry
- Hydrogel
What types of dressing should be used at the granulation stage of wound healing?
- Dry, non-adherent
- Semi-occlusive: absorptive e.g. allevyn (non-adherent, semi-occlusive absorptive, removes some exudate from wound)
- Occlusive: active rehydration e.g. granuflex
Describe the layers of dressings for soft tissue wounds
- Primary/contact layer dependent on wound/stage of healing
- Secondary layer: absorbent to avoid maceration and provide degree of support
- tertiary layer: supportive, allows evaporation, protects dressing from further environmental damage
Outline the conservative management of pelvic fractures in small animals
- Less invasive, cheaper
- outcome less predictable (often poorer)
- Recovery more prolonged
- Cage rest, analgesia, usually 6-8 weeks
- Generally few complications
- Especially good in smaller individuals
Outline the surgical management of pelvic fractures in small animals
- Invasive, expensive
- More rapid and fuller return to function
- Rapid pain relief, potentially better outcomes
- No pelvic narrowing and risk of chronic constipation
- No distortion of pelvis
What factors should be considered the indications for surgery on a pelvic fracture?
- Is patient ambulatory?
- How long fracture has been present
- Weight bearing axis involvement
- Acetabulum required?
- Pelvic canal diameter reduction?
- Patient intractably painful?
- Additional fractures eg. limb fractures?
- Presence of neurological deficits
Explain whether surgery is indicated in a cat with sacroiliac luxation with an ischial fracture
May only be marginally displaced and so surgical stabilisation would provide little advantage
Explain whether surgery is indicated in a cat that has been missing for a week and a half, and returns with pelvic fracture
Likely that injury is a week and a half old, fragments will be difficult to move at this point and so surgery is not indicated
What forms the weight bearing axis of the hip?
Hip, ilial shaft and sacroiliac joint
What treatment is indicated with a fracture of the pelvis that does not affect the hip, ilial shaft or sacroiliac joint?
Weight bearing axis not affected, so surgery is not required
What degree of narrowing of the pelvic canal is an indication for surgical treatment and why?
- > 50% narrowing
- Risk of chronic constipation which would also require further surgery
Explain how multiple fractures affect the indication for surgical repair of a pelvic fracture
Multiple fractures = less able to cope, esp. if FL as well as hip, surgical repair of pelvic fracture indicated
Under what conditions may second intention healing of a sacroiliac subluxation be reasonable?
If >60-80% of joint surface is overlapping and animal not in significant pain
What does a unilateral sacroiliac luxation indicate?
Must be other pelvic injuries present, may be minor but must identify these
List the management options for sacroiliac luxations/sacral fracture
- Conservative if >50% of articular surface intact
- Surgical management: large lag screw +/- anti-rotation wire, or trans ilial pin
Discuss the use of surgical management for sacroiliac luxations/sacral fracture
- Can be difficult, prone to error
- Aim to place screw through ilial wing into body of sacrum, easy to miss
- Too ventral = not enough bone purchase
- Too dorsal: enter spinal cord causing neurological damage
Describe the common pattern of ilial fractures
- Usually long oblique fractures
- Caudal fragment often displaces medially, narrowing the pelvic canal diameter
Outline the treatment of ilial fractures
- Well contoured plate placed
- +/- lag screws
- Cage rest for week or so, then start to relax if stable for period of time where movement is going to be unlikely/limited
Discuss some surgical complications that may occur with ilial fracture repair
- Reduction difficult if chronic injury (>5 days old)
- Iatrogenic damage to sciatic nerve (runs over ilial shaft)
Compare the weight bearing aspects of the acetabulum in dogs and cats
- Dogs: dorsocranial aspect
- Cat: mid region
List the most common methods of repair for acetabular fractures in small animals
- Referral required
- Plate fixation (locking plate most commonly)
- Mid acetabulum: screws, wire, methylmethacrylate composite
- Complex/cost issues: femoral head and neck excision
What are the main risks associated with pubic fractures in small animals?
Soft tissue damage and risk for herniation of abdominal contents (as a result of pre-pubic tendon avulsion)
Describe capital physeal fractures of the hip
- Slipped epiphysis of hip
- Salter Harris Type 1
- Usually 6-7mo
- Epiphysis remains in acetabulum attached to the teres ligament
- Often minimally displaced
- More common in cat than dog
What radiographic views are best in order to identify capital physeal fractures in small animals?
Frog leg view - standard VD view will close the fracture as a result of extension of the hip
Outline the management of capital physeal fractures
- Stabilise with 2-3 K wires or lag screw
Describe the common consequences of capital physeal fractures
- Apple coring (neck of femur resorbs over period of time) common 3-6 weeks post-op due to vascularisation of femoral neck and subsequent bone remodelling (not usually a clinical problem)
- Premature physeal closure and development of DJD is common
- Poor healing in Burmese cats reported
List the different types of jaw fracture/luxation
- Mandibular symphyseal separation
- Maxillary fractures
- Temporomandibular luxation
What are the most common causes of mandibular symphyseal separation?
- Blow to head from car
- Fall and hits chin on ground
