SA developmental disease Flashcards
What is hip dysplasia?
Hip dysplasia is an inherited developmental disease of the hip joint, characterised by hip laxity and the development of osteoarthritis
How comon is hip dysplasia?
- Very common disease that usually affects both hips
- May not be devastating disease, with many dogs and cats showing minimal or no clinical signs
Who is effected by hip dysplasia?
- Affects all breeds of dog although prevalence is higher in large and giant breeds
- No sex predisposition
- In cats, higher prevalence in Maine Coon, Persian, Devon Rex and Himalayan
What can be seen here?
Hip dysplasia
Left: subluxated Right: completely luxated
Both can see femoral neck and acetabular changes
What is the causative pathogenesis of hip dysplasia?
Inherited, mechanism of inheritance is consistent with a polygenic trait (the phenotypic expression is influenced by genetic and non-genetic factors)
Variable estimates of heritability ranging from 0.2-0.6 depending on population studied
Non-genetic factors that may play a role in the expression of the disease include
- Body size
- Growth rate
- Nutrition
- Exercise
- Muscle mass
What is the aetiopathogenesis of hip dysplasia?
- Grossly normal at birth
- loss of congruency between articular surfaces of the acetabulum and femoral head
- This loss of congruency leads to the development of osteoarthritis and bone remodelling
- Pain in initial stages thought to be the result of stretching of the joint capsule and microfractures in the dorsal acetabular rim
- Pain subsides in many cases following the gradual increase in stability afforded by the intra-and periarticular changes (mainly, thickening of the joint capsule)
What can be seen in this image?
Red dots: show that the femoral head has subluxated they aren’t where they should be
Yellow wibbly line: remodelling changes that are trying to stabilise laxity
Yellow arrows: pointing to new bone growth/sclerosis.
What are the signs of osteoarthritis in Hip dysplasia?
- Changes in shape of the dorsal acetabular edge
- New bone formation in the acetabular fossa, the cranial and caudal acetabular edges, femoral head and neck
- Degree of remodelling of the femoral head and neck
What is the Norberg-Olsson angle?
Angle used to assess hip dysplasia
- Angles smaller than 105 degrees are considered abnormal
- To create mark centre of femoral head and draw straight line between them. Then a line going forwards that touches cranial aspect of acetabular ring and this angle is called the norberg-olsson angle.
What is the warning associated with radiographic interpretation of Hip Dysplasia?
- There is poor correlation between the severity of radiographic changes and the clinical signs
- Many dogs (and cats) show radiographic features of hip dysplasia but no clinical signs
What are the D/dx for Hip dysplasia in young dogs?
Differential diagnoses in the young dog
- Patellar luxation
- Cranial cruciate ligament disease
- Hock and stifle osteochindrosis
- Legg-Calve-Perthes disease
- Septic arthritis
- Spinal disorders
- Myasthenia gravis
- myopathies
What are the D/dx of hip dysplasia in the mature dog?
Differential diagnoses in the mature dog
- Cranial cruciate ligament disease
- Patellar luxation
- Degenerative lumbosacral disease
- Other spinal disorders
- Achilles tendinopathy
- Septic arthritis
What are the clinical signs of Hip dysplasia in young animals? (4-10 months of age)
Young dog (4-10 months of age)
- Variable degree of pelvic limb lameness
- Swaying of the pelvis when walking
- ‘Bunny-hopping’ gait at faster speeds
- Weakness of the pelvic limbs
- Reluctance to exercise
- Inability to jump
- Inactivity stiffness
What are the clinical signs of Hip Dysplasia in the adult dog (over 12 months of age)?
Adult dog (over 12 months of age)
- Difficulty rising
- Pelvic limb inactivity stiffness (often worse after exercise)
- Exercise intolerance
- Difficulty jumping
- Behavioural changes (e.g. aggression when hindquarters touched)
- Sudden onset lameness (uncommon)
Discuss bi-modal hip dysplasia clinical signs?
The clinical signs associated with HD typically have a bimodal age distribution:
- Although clinical signs can appear at any age, many dogs under 1 year that are affected present with signs related to hip instability and secondary synovitis
- Older dogs present with signs related to hip osteoarthritis
Be aware that because of the high prevalence amongst dogs, HD tends to be over-diagnosed in both immature and older dogs
Strictly define elbow dysplasia?
Elbow dysplasia may be strictly defined as the abnormal development of the cubital joint
In dogs, numerous disease processes have been included under the term elbow dysplasia; however, three main diseases predominate, these are?
- Un-united anconeal process (UAP)
- Fragmentation of the medial coronoid process (FCP)
- Osteochondritis dissecans (OCD) of the medial portion of the humeral condyle
Define Elbow dysplasia?
Elbow dysplasia may be strictly defined as the abnormal development of the cubital joint
What is the liklihood of having the conditions that predominate in causing elbow dysplasia?
Un-united anconeal process (UAP)
Fragmentation of the medial coronoid process (FCP)
Osteochondritis dissecans (OCD) of the medial portion of the humeral condyle
- Each condition is usually seen in isolation but any combination of the three is possible
- Having all three conditions at once is unlikely
Other diseases implicated in elbow dysplasia are?
- Joint incongruity
- Incomplete fusion of the medial epicondyle
- Idiopathic osteoarthritis of the medial compartment of the elbow joint
Do cats get elbow dysplasia?
Elbow dysplasia has not been reported in cats, although there is ever greater recognition of osteoarthritis of the elbow in this species
How does the anconeal process usually develop and how does this differ in the GSD?
Normally the anconeal process develops as part of the ulna diaphysis but in certain breeds (e.g. GSD) it develops as a separate centre of ossification
How does a UAP occur in a basset hound and other similar breeds?
In certain breeds (e.g. Basset Hound) separation is secondary to non-traumatic premature closure of the distal ulnar growth plate
The instability and irritation following separation of the anconeal process causes?
- osteoarthritis
- Often seen in association with FCP (diagnosed at arthroscopy)
Look at an image of a UAP?
What does A mark?
Anconeal process
How is a UAP diagnosed?
- One or both elbows
- Progressive thoracic limb lameness at about 4-5 months of age
- Strange gait with elbow abducted (may have outward rotation of the foot)
- Palpation/manipulation will reveal joint thickening and varying amounts of joint effusion
- Reduced joint movement, pain, maybe crepitus
What breeds is UAP common in?
Predominantly GSD although other large-breed dogs such as Wolfhound, Rottweiler, St. Bernard and Great Dane
How is diagnosis of UAP confirmed?
- Diagnosis confirmed by taking a fully flexed lateral radiograph of the joint (avoid superimposition of the medial epicondyle on the olecranon)
- Arthroscopy can be performed but is more useful for evaluation of the remainder of the joint for FCP and OCD
What is currently the commonest cause of elbow lameness in young, rapidly growing dogs of large and giant breeds •Rottweilers, Labrador retrievers, Bernese mountain dog (also GSD, golden retriever, St. Bernard, chow chow, Rhodesian ridgeback, Newfoundland)?
Fragmentation of the medial coronoid process
There is no separate centre of ossification for the coronoid process so why it becomes fragmented is less clear cut but possible causes are?
- osteochondrosis
- microfracture/fracture
- radioulnar incongruity
- humeroulnar incongruity
What is the pathology of FCP?
- Currently, one or more fragments of bone may have fractured from either the inner aspect of the medial coronoid process immediately adjacent to the radial head, or from the apex of the process
- Fragment/s often remain attached to the annular ligament
- The fragment/s may project causing erosion of adjacent medial humeral condyle (kissing lesion)
Illustrate where a FCP occurs?
Look at this FCP pathology?
What are the clinical signs of FCP?
- Outward rotation of pes
- Reduced range of flexion and extension
- Painful response to external rotation and hyperextension
- Crepitus in advanced cases
What can be seen on radiography of a FCP?
Difficult to see lesions on conventional radiographs (large fragments might been seen on craniocaudal or craniolateral-caudomedial oblique projections)
CT scans much better and will allow assessment of congruency as well
Arthroscopy –Will allow diagnosis of definitive type and severity of elbow dysplasia
Show how hard it is to see FCP on radiograph?
What is the best imaging modality to diagnose FCP?
What might you see on arthroscopy of FCP?
What is the aetiology of OCD of medial condyle?
- Aetiology and pathogenesis of OCD of the canine elbow joint is poorly understood
- Lesion initiates deep within the articular- epiphyseal cartilage complex in the developing joint
- Necrosis of vascular channels lead to development of a cartilage flap (?)
- Highest incidence in Labrador and golden retrievers
- Commonly, bilateral involvement
Where is the OCD lesion usually seen?
- Lesion is usually found near outer edge of the central weightbearing region of the articular surface of the medial part of the humeral condyle
- OCD may be identified in conjunction with FCP and medial compartment osteoarthritis
Outline where OCD, FCP and UAP can be seen?
What can be seen here?
OCD of medial condyle
How can OCD be diagnosed?
Clinical signs
- Clinical signs are very similar to FCP
Radiography
- Flexed lateral radiograph will show presence of osteoarthritis on the anconeal process
- craniocaudal or craniolateral-caudomedial oblique projections will usually reveal a defect in the subchondral bone of the medial part of the humeral condyle
- CT scans will allow for good assessment, etc.
Arthroscopy
- Diagnosis and treatment may be performed through arthroscopy
Compare radiographs and CT images of OCD?
How does OCD appear on arthroscopy?
Define Varus?
Varus = medial deviation of the distal limb
Define Valgus?
Valgus= lateral deviation of the distal limb
Unilateral angular limb deformities usually occur as a result of?
Usually occurs as a result of trauma to all or part of an active growth plate = immature dogs
It can also result from:
- other conditions involving abnormal endochondral ossification e.g. retained cartilagenous core
- other conditions affecting the growth plate e.g. metaphyseal osteopathy
Bilateral angular limb deformity usually occurs due to?
a systemic problem eg nutrition, growth rate etc
Most severe consequences of angular limb deformity are when?
One of a set of paired bones involved (e.g. radius and ulna, or tibia and fibula)
What is happening in each of these images?
1st image: growing normally
2nd image: Varus abnormality as medial half of the radial epiphysis has fused prematurely so ulna has continued to grow causing varus abnormality
3rd image: Lateral side of radial epiphysis has fused creating a valgus abnromality
4th image: distal ulna fused prematurely causing valgus abnormality
What are the clinical signs of angular limb deformity?
- ‘bent’ leg
- variable degree of lameness depending on severity of deformity
- most severe problems when animal cannot placed paw ‘flat’ on the ground
- lameness more severe when elbow affected
- Therefore lameness resulting from an ALD can have both painful and mechanical elements to it.
How should radiography be performed for ALD?
- Good quality orthogonal views of both legs
- Include all of antebrachium with elbow and carpal joints, and at least proximal ½ of metacarpals / metatarsals
- Straight elbow -let rest of leg do it’s own thing
- Measure and record degree of valgus / varus
- Measure and record length of radius and ulna
- Up to 15 degrees valgus angulation is usually clinically insignificant
Describe premature closure of the distal ulnar growth plate?
3D deformity:
- distal limb valgus
- external rotation of the foot
- cranial bowing of the radius
Can result in:
- elbow incongruity
- antebrachiocarpal joint incongruity (less commonly)
Compare normal and abnormal limbs?
What can be seen here?
Curvature has occurred as a result of early ulna closure causing the radius to curve
How is premature closure of the distal ulna GP –> leading to short ulna managed in the immature animal?
Immature animal:
- Main concern is elbow joint incongruity (= elbow pain) and secondary concern is the valgus deformity (= carpal pain/pad sores etc)
- Surgical techniques use the remaining growth of the radial growth plate to help correct the angular limb deformity slowly over time
How is premature closure of the distal ulna GP –> leading to short ulna managed in the mature animal?
Mature animal:
- main concern is elbow joint incongruity (= elbow pain) and secondary concern is the valgus deformity (= carpal pain/pad sores etc)
- radius is cut and re-aligned
What are the surgical options for ALD before skeletal maturity?
If the dog is young and still has considerable growth potential, consider:
- proximal ulnar osteotomy to improve elbow incongruity
- distal ulnar ostectomy to remove bow-string effect and preserve elbow joint
- stapling the medial side of the radius
What surgical procedure has been done here?
Proximal (‘dynamic’) ulnar osteotomy
Young dog still capable of growing can see incongruity in left image. Proximal ulna osteotomy has made elbow joint congruent again post op on the right.
What has been done here?
Ulnar ostectomy and radial stapling or use screws and wire
This aims to slow down the radial growth to discourage joint from moving in the hope dog may grow out of the problem
What are the treatment options for near skeletally mature dogs with ALD?
Elbow incongruity remains priority –proximal ulnar osteotomy if necessary
Bones have stopped growing, and so will not ‘self- correct’, therefore:
- distal ulnar ostectomy, and
- radial osteotomy with either:
- one stage correction and stabilisation using linear external skeletal fixator or bone plate
- ‘staged’ correction using Ilizarov fixator
What is going on here?
- Osteotomy & External Skeletal Fixator (one stage / static correction)
- This treatment is reserved to dog that is no longer growing
