Lameness and orthopaedic disease Flashcards
What to do first for lameness
- History
- Physical examination
- observation from a distance
- direct palpation
- ancillary tests
- Lameness examination
- basic examination
- additional movements/surfaces
- evocative tests
- “A clinical sign, [manifesting] signs of inflammation
including pain, or a mechanical defect that results in a
gait abnormality
Five “types” of lameness
* supporting limb (stance phase) lameness
* swinging limb lameness
* mixed lameness
* compensatory lameness
* induced/artefactual lameness
Almost never shoulder lameness – most common foot and less common more
proximally
Breeds of horse and levels of activity
Septic synovitis – hunting or jumping – hedges and thorns
Dressage – strains on ligaments – repetitive
Shetlands – more common shoulder – OCD shoulder
Forelimb much more common
Signalment clues for lameness
- Specific age groups often suffer from specific conditions:
- foals: haematological septic arthritis, lateral luxation of the patella
- young, skeletally immature animals: developmental orthopaedic diseases including OCD, stress related injuries (esp TB horses)
- older horses: chronic progressive OA, navicular disease
- … but these are not necessarily exclusive
There are very few sex related conditions; however, breeding potential may be important for treatment
* may also see behavioural changes associated with oestrus
* RER has been shown to be more common in female TB and event horses (recurrent equine rhabdomyolitis)
* anecdotally lameness has been implicated in cryptorchid animals
History: signalment
* Knowledge of the discipline and breed of the animal is extremely important
* certain disciplines will place unique strains on animals
* some manifestations of lameness are seen in all groups of animals
What history questions to ask for lameness
Conformation
Posture
Symmetry
Palpation
Cervical
- When did the owner first notice the problem? Is there a history of trauma?
- Have any treatments been attempted?
- What is the nature of the lameness?
- Does it improve with exercise? Is it worse on different surfaces/with different tack?
- Have there been any recent changes in management/exercise level/paraprofessional
involvement? - Is there any previous history of lameness?
- Understanding how conformation affects lameness is very important
- severe conformational abnormalities are easy to appreciate
- asymmetry of conformation is often particularly important
- there may be important breed characteristics that lead to lameness e.g. long toe/low heeled TBs
Hock conformation - hind limb suspensory desmopathy - poor prognosis with straight hocks
Posture - Careful observation from a distance is extremely important
* laminitis or severe skeletal injuries might be readily obvious
* pointing or reduced weight-bearing
* “dropped elbow” indicates failure of the triceps apparatus - olecranon fracture
* cervical pain
* upward fixation of the patella
* (neurological conditions)
- Asymmetry is often very important in lameness evaluation
- muscle atrophy (disuse or neurogenic)
- foot size
- fetlock height/angle
- localised swelling (synovitis, cellulitis, exostosis/callus formation)
- bony asymmetry (e.g. scapular height, tuber coxae/sacrale)
Looking for muscle atrophy – looking front or side – undeveloped – not using or
neurogenic
Foot size – chronic lameness
Fetlock – more weight – hyperextension – or failure of suspensory apparatus
Swelling – effusion of synovial structures, exosthosis – bone spurs
A good and systematic routine is vitally important
* always use the same system every time
* this will vary amongst individuals but choose a system that suits you
* examine limbs during weight-bearing and elevated from the ground
* ideally perform static examination before dynamic examination
- This should include assessment of:
- asymmetry
- signs of inflammation
- pain (by both deep palpation and induced movement)
- loss of function e.g. range of movement
- crepitus
- peripheral pulses
- Examination of the poll including wings of the atlas
- Palpation of the para-spinal musculature
- Palpation of the brachiocephalicus muscle
- If indicated assessment of the range of cervical movement using food
What are we assessing with forelimb lameness assessment
Shoulder and bicipital region
* Elbow and antebrachium
* Carpus
* Metacarpal region
* Fetlock
* Pastern
* Foot
* should include use of hoof testers
How to test thoracolumbar spine
- Use digital pressure to assess dorsal contour
- Deep digital pressure of the epaxial muscles is resented by many horses and is not pathognomomic for back pain
- pressure over the thoracic and cranial lumbar region usually results on lordosis
- pressure over the caudal lumbar and sacral region results in kyphosis
- often lack of these actions more indicative of back pain
- Often back pain is secondary to hindlimb lameness
What structures are we assessing for hindlimb lameness assessment
- Femoral region
- Stifle
- Tibia
- Tarsus
- capped hock, bog spavin, bone spavin, curb and thoroughpin
- Metatarsophalangeal region
- Fetlock
- Pastern
- Foot
Capped hock –
Bog spavin – swelling of tarsocrurual joint
Spavin – OA of small tarsal joints
Curb – swelling of plantar ligament
Thoroughpin – effusion of dft tarsal sheath
How to assess pelvis
- Often externally palpable abnormalities of the pelvis appreciated during observation
- include gentle rocking of the pelvis to detect crepitus
- generally performed last due to inherent risks
- include basic neurological assessment (tail tone, lower motor neurone function)
General clinical exam for lameness
- This should not be overlooked
- pyrexia may be concurrent with septic arthritis especially in the foal
- Lameness and gait abnormalities may also result from other conditions
- peritonitis/pleuritis, abscessation, genito-urinary disease
- One should never forget that “common things are common”
- however, good and systematic examination will help identify those uncommon cases
How to do dynamic exam
- Select an appropriate environment and surface
- safety of the horse and handler are paramount
- select an even, straight, firm surface free from distractions; however, alternate surfaces can be useful
- explain to inexperienced handlers exactly what you require
- Examination should attempt to assess:
- baseline lameness (i.e. before provocative tests) or lamenesses
- attempt to identify multiple limb lameness, and also establish whether these are primary or secondary problems, or if they are artefactual
- any lameness identified should be graded and immediately recorded to attempt to create a degree of objectivity
Lameness grading
- Several systems exist
- Ten point grading system (more commonly adopted in
Europe) - Five point systems usually attempt to be more objective
- care as different systems exist
- especially in the UK clinicians will refer to a 5 point system
without appreciating any objective nature
1 - Lameness difficult to observe and not consistently apparent regardless of circumstances (such as weight carrying, circling, inclines, hard surfaces)
2 - Lameness difficult to observe at a walk or trotting a straight line but is consistently apparent under certain circumstances (such as weight carrying, circling, inclines, hard surfaces)
3 - Lameness consistently observable at a trot under all circumstances
4 - Obvious lameness with marked nodding, hitching, or shortened stride
5 - Lameness characterized by minimal weight bearing in motion or at rest and the inability to move
Assessment at walk
- The horse should be walked at a steady pace away from and towards the observer
- observe horses carefully during the turn
- Careful attention should be placed upon
- foot placement
- gait abnormalities (e.g. “dishing”, “plaiting”)
- Include lateral observation to assess:
- foot flight
- “tracking up”
- cranial and caudal phases of the stride
Dishing – moving feet outwards
Plaiting – moving feet inwards towards straight line
Tracking up – hindlimb placement should be in footprints of forelimbs
Caudal how far back before picking limb up, cranial how far forward placing foot
Mechanical and neurological lameness
- Alternative/mechanical causes of lameness:
- “stringhalt”
- fibrotic myopathy
- upward fixation of the patella
- “shivers” syndrome
- Always remember to assess neurological function especially in young horses
- ataxia is difficult to define but important to remember that the etymology is from Greek (without order/regular arrangement i.e. inconsistent)
Stringhalt – hyperflexion of hind – uni or bi. No lack of performance – plant toxin in
Aus and UK
Fibrotic myopathy – scarring of muscles of hindlimb
Upwards fixation of patella – locking
Ataxia is not lameness
Examination at trot
Examination at trot
* Horse should again be moved at a steady pace away from and towards the observer
* ensure that the handler does not constrain the horse’s natural movement
* pace can sometimes mask or complicate assessment so different speeds can be useful
* assessment now focuses less on the foot placement and more on other alterations in gait
Forelimb lameness
- “Head nodding” is the most useful method of forelimb lameness assessment
- head elevation begins just before the stance phase of the lame limb
- results in reduced ground reaction force (GRF) due to upwards acceleration of the head and neck, and caudal movement of the centre of gravity
- consequently the horse appears to nod when the “good” leg is in contact with the ground
Hindlimb lameness
- Relative excursion of the tuber coxae is generally the accepted visual method of assessing hindlimb lameness
- often given terms like hip or pelvic “hike”
- the limb with the greater degree of movement is the lame limb
- visual cues can be improved by placing tape on each hindlimb running between the tuber coxae and tuber sacrale
- Hind limb lameness is harder to appreciate than forelimb lameness
Hindlimb lameness can mimic forelimb lameness at trot
* when the lame limb hits the ground the horse moves it centre of gravity cranially to help unload the limb
* the two-beat gait means that there will be a head nod during the stance phase of the contralateral forelimb
* therefore the horse appears to be lame on the ipsilateral forelimb to the lame hindlimb
* It should be noted that this is generally apparent only if moderate lameness is present
Additional assessments
* There are many other visual (and audible) clues which may help with lameness
* Unless riders are very experienced try to avoid their advice
* it is very difficult to differentiate forelimb and hindlimb lameness from the saddle
* owners are also more likely to be biased following diagnostic anaesthesia
* this does not, however, suggest that riders input is not valuable during lameness assessment
Additional assessments
Sound
* excluding all visual clues and listening to syncopation can be extremely useful (remembering the beats of the four standard gaits)
Fetlock drop
* at trot because there is a higher GRF in the sound (less lame limb) the fetlock will drop further
* structural disruption of the suspensory apparatus and flexor tendons will typically result in over-extension of the affected limb at walk
- Most lameness results from pain during limb loading
- therefore horses will attempt to reduce the duration of the stance phase
- can be especially useful in the assessment of hindlimb lameness during lunging exercise
Lunging
- Helpful in ascertaining there might be a bilateral component to lameness
- Lunging on different surfaces can also be extremely
useful - Beware of over interpretation
- “soft tissue lameness is worse with the limb on the outside/when lunged on soft ground”
- very tight circles on hard ground can evoke forelimb lameness of questionable significance, especially in heavier horses
At canter
Three beat gait
* L lead: LF, RF and LH, RH
* although RH contacts the ground on its own, stance phase, GRF and degree of flexion in the proximal joints is greater in the LH
* therefore a horse with a RH lameness may possibly prefer to canter on a left lead
* R lead: RF, LF and RH, LH
Ridden
The additional weight of the rider can elicit lameness in either the forelimbs or the hindlimbs
* subtle changes in weight can also mask signs of lameness
* having an experienced rider can be extremely useful especially when evaluating subtle poor performance issues
Flexion tests
Important to remember that these are not specific to one particular structure
* Different clinicians will also apply different forces
* consequently you need to be familiar with the normal responses to flexion
* it is possible to induce lameness
* studies show that 100-150N is optimal (????)
* aim to flex the limb to a point slightly before a withdrawal response is elicited
* No clear guidelines as to how long flexion should be applied
* most clinicians use 60 seconds
* however, it has been shown that 5 seconds of flexion generally produces similar results to 60 seconds in many cases
Horse temperament in lameness exam
- Safety of the horse and handler should be the first consideration
- acepromazine can be useful in calming fractious horses without providing analgesia
- some clinicians advocate low doses of xylazine; however, this will be analgesic and may result in ataxia
- more frequently xylazine is used to facilitate local anaesthesia in which case it is important to allow sufficient time for the effects to wear off
Forelimb static exam
Restrain and calm to examine
Palpate both legs
Look for heat, pain and swelling - synovial effusion
Dont jump to conclusions - may be old or insignificant - good records, history, dynamic and diagnostic tests
Principles of forelimb diagnostic anaesthesia
Aseptic, new bottle, sterile needle/syringe, prep (dont need to clip unless very hairy)
Mepivicaine - least tissue reaction. Bupivicaine slightly longer action but expensive
Place down leg
Needle seperate
VAN - nerve more palmar
DO NOT if
Suspect fracture of severe soft tissue injruy - DDFT rupture as will weight bear and catastrophic
Risk of infection - existing skin disease or cannot clean
Cannot perform safely
Start distally and work proximally
Palmar digital
Abaxial sesamoid
Low four point - fetlock and below
High four - metacarpal and below
Lateral palmar nerve - proximal suspensory
Static hindlimb examination
Stand square, both sides, conformation, asymmetry, muscle wastage, swelling - from side
Scoliosis - sway back or roach back
Hock conformation - straight hocks
Flexural conformation distal limb - hyperflexed fetlock
Symmetry of gluteal muscles
Tuber sacrum top
Tuber coxae
Tuber ischii
Bow legged (valgus - hocks out) or cow hocked (varus - hocks in)
Palpate for heat, pain, swelling
Stifle - will feel femoropatellar - patella ligament - effusion
Medial - feel effusion in medial femorotibial joint - lateral much harder
Hock - tibiotarsal most motion joint
Distal intertarsal and tarsometatasal
Fetlock - plantar pouch effusion, DFT sheath effusion,
is it dorsal or plantar to suspensory branch - plantar is flexor tendon, dorsal is fetlock joint
Remember with limb elevation - hock and stifle move together - suspensory apparatus
Hoof exam
How to make hindlimb regional anaesthesia safer?
Restraint of patient - handler, nose twitch, chemical restraint, lift ipsilateral forelimb
Personal safety - hat, case by case
Clipping - may well increase skin contamination - only clip if makes identifying landmarks easier
When is low 6 point used in hind limb over a low four point
Dorsal metatarsal nerves are the 5th and 6th point - important for skin sensitivity
What is main difference between perineural blocks and synovial blocks?
Synovial -into synovial structure - much more specific to structure injected - can return to block more distal structures
Perineural - need to work sequentially distal to proximal - each block adds additional areas of desensitisation
Where to start with hindlimb anaesthesia
Acute lameness, positive to proximal limb flexion (unilateral), effusion of medial femorotibial joint
Stifle
Where to start hindlimb anaesthesia
Chronic bilateral lameness in sports horse - mild to moderate positive to proximal flexion
Tarsal region - small tarsal joints or proximal suspensory ligaments
Where to start hindlimb anaesthesia
Acute unilateral lameness in native pony with marked digital flexor tendon sheath effusion
DFTS
What perineural nerve blocks can we do in hindlimb?
Plantar digital
Abaxial sesamoid
Low 4 point
Deep branch of lateral palmar
Tibial and peroneal
Deep branch of lateral palmar nerve - DBLPN
How to do
Fairly specific block for proximal suspensory ligament
- Limb is held flexed and rested on the vets knee
- The flexor tendons are pulled medially to open up injection site
- Needle is advanced along the axial surface of the lateral splint bone
- 3ml of local anaesthetic solution is injected (resistance should be low)
- The horse is re-examined after 10 minutes
What factors classify a fracture in horse
Location - which bone and where
Structures involved - articular vs non articular - synovial sepsis or not
Contamination - open or closed - bone contamination or skin barier
Extent of damage - complete vs incomplete, simple vs comminuted, complete both sides of bone or multiple pieces
Size of fragment - chip vs slab vs shaft fracture - shape or direction, chips
Fracture configuration - transverse, oblique, spiral, avulsion, growth plate
Displacement, fragments, margins
What are the different fracture types for pedal (p3) bone
Type 1 - wing fracture
Type 2 - articular wing fracture
3 - straight down middle - articular
4 - extensor process fracture
5 - comminuted fracture
6 - chip fracture
7 - foal - chip
Causes of fracture in the horse
Trauma - most common cuase, can be acute (kick, fall), or chronic repetative (stress in racehorses, general wear and tear)
Developmental - msot commonly due to OCD or other developmental orthopaedic disease
Secondary to other disease conditions - neoplasia or infection - uncommon but important
Common fracture sites - kick
splint bones, stifle bones (tibia, patella), olecranon, head
Common trauma/fall fracture sites
Head, vertebrae, long bones - femoral or cannon in anaesthetic recovery, joints during competitions - patella from hitting fence
Common repetative wear fracture sites
Distal phalangeal (pedal, p3), middle phalangeal (p2, pastern), distal sesamoidean (navicular bone)
Navicular disease and remodelling - secondary to wear and tear with mechanical changes
Common stress fracture sites
In racehorses - anywhere
Carpal bones - radius, radiocarpal, third carpal
Third metacarpal bone (cannon), middle phalangeal (pastern), proximal sesamoidean bones, radius, tibia, pelvis, vertebrae
Clinical signs of fracture
Range from mild / subtle to marked / severe!
Acute, severe or displaced fractures will have obvious conformational abnormalities, severe lameness, pain and crepitus at the fracture site
Non-displaced fractures (including stress fractures) and small chip fractures may have
minimal lameness and localising signs
Articular fractures normally have joint effusion
Know your anatomy, palpate carefully!
Diagnostic approach to fractures - history
Physical exam
Major red flags for fractures are history of trauma (e.g. kick or fall), acute onset severe lameness, acute onset joint effusion, heat, pain, swelling and palpable crepitus
Non-displaced stress fractures may present as acute onset lameness following exercise, which resolves over a few days
Non-displaced, repairable fractures can progress to catastrophic irreparable fractures if not recognised and treated appropriately
Physical exam
Careful and detailed palpation for heat, pain, swelling and crepitus.
Crepitus due to air/gas under skin is usually diffuse and non painful. Crepitus due to bone fragments is painful and localised.
Administer sedation and analgesia as needed until horse is calm and can be examined thoroughly
If attending event / accident and examine immediately, then consider re-examining later.
Exhausted or excited horses may mask some of the signs initially. Swelling and heat can take a few hours to appear.
Consider what underlying / associated structures may be affected
Diagnostic tests for fracture
Nerve or joint blocks – avoid if possible, only use is in chronic, mild, small fractures
Radiography – first line approach for most fractures
Minimum of two views
Some regions may not be accessible for radiography
Non-displaced fractures may not show any radiographic changes
Ultrasound – main use is in pelvic fractures in racehorses#
Gamma scintigraphy - valuable for non displaced stress fractures or areas which cannot be accessed with radioraphy - vertebrae, ribs, scapula, pelvis
CT - gold standard but availability of facilities and cost
Possible fracture complications
Articular involvement –> degenerative joint disease
Contamination -> osteomyelitis, synovial sepsis, soft tissue infection
Soft tissue involvement -> tendon, ligament, muscle or neurovascular damage
Unstable -> non-healing or malunion
Damage to periosteal vascular supply -> sequestrum formation
Mechanical overload of contralateral limb -> laminitis
Avoided by
- Recognise fracture promptly, adequate stabilisation
Do NOT nerve block or exercise if risk of fracture
Provide adequate support, splinting to prevent further damage - if travelling or moving as well
Cover and protect open wounds
Assess carefully for involvement of other structures - radiography for articular involvement, US to assess soft tissue, neuro for suspect nerve damage
Articular fractures
- Remove small unstable articular fractures which are non an integral part of articular surface and will cause trauma if left
- Stabilise large fragments which are an integral part of articular surface - screw, plate
- Arthrodesis is viable option for low motion joints - pastern, carpometacarpal, distal tarsal joints
Contamination
Internal fixation of open fractures is rarely successful
Open contamination / infection of a major fracture is a major complication
Identify, flush and protect and any wounds
Administer systemic antibiotics
Soft tissue involement may be limiting factor
- Complete tendon rupture - will drastically change prognosis of simple fracture
Which fractures to euthanase
Open, comminuted long bone fractures
Complete fractures of scapula, humerus, radius, femur and tibia in horses over 500kg
Consult insurance where possible
Seek advice from senior partner or referral surgeon as needed
If fracture is irreperable
Cannot be stabilised, transported for appropriate treatment
Quality of life long term will be poor - articular damage to arthritis
Owner cannot affort
Horse will not tolerate box rest, rehabilitation - preexisting conditions, temperament, behaviour
Horse will not return to previous work
Needs to be dialogue with owner - human factors and owner circumstances
Equine welfare long and short term
4 levels of triage
1 - immediate action or might die - head or spinal traima, internal injury, haemorrhage
2 - do not move or come become unfixable - fracture, tendon rupture, laceration, joint instability, vascular or neurological damage
3 - Urgent attention or prognosis wil be compromised - synovial or bony involvement, contaminated wounds
4 - delayed action - does not need urgent emergency visit
What to look for to triage on physical exam
Crepitus - fracture or emphysema
Degree of contamination
Soft tissue involvement
Bony involvement
Swellings and effusions
