Hip dysplasia Flashcards
What is the heritability percentage of hip dysplasia?
20-30%
Are dogs with HD born with bad hips?
No, HD is a developmental disease as dogs are born with normal hips, but have a genetic predisposition to hip joint laxity
At what age can the inciting laxity start?
As early as 30 days old
When can HD be diagnosed clinically?
From four months old, subluxation and poor congruency between femoral head and the acetabulum.
What are the secondary changes of HD and why?
Forces are not transmitted across the joint normally, leading to overload of areas of articular cartilage resulting in degeneration, development of joint capsule thickening, periarticular fibrosis and healing of microfractures.
what is the typical distribution of clinical signs of hip dysplasia?
Bimodal - at early age (<12m) when hip laxity is seen and pain as a consequence - fibrosis stabilizes the joint, then again with OA at a later stage in life (>2yrs)
Which breed dogs are prevalent?
Medium to large breed dogs
Labrador retrievers
Clinical signs of HD?
mild stifness on rising, reluctance to jump, wiggle walk
bunny hop
Diagnosis of HD on clinical exam?
Barlow test
Bardens hip lift test
Ortolani test
Are done under sedation/anesthesia!
Radiographic changes in HD of young animals?
Acetabular coverage of femoral head should be more than 50%
Early secondary changes can be seen
! Beware of insertion of capital ligament !
Radiographic changes of HD in older animals?
Osteophytes - new bone formation
Flattening of femoral heat
Flattening of acetabulum
New bone formation of femoral neck
Thickening and/or capsule mineralization
Subluxation to completely luxoid
Treatment - conservative management - indications?
First line in young and old dogs
75% of young animals with HD will go on to have minimal gait abnormalities when 15months old
What is part of conservative treatment in HD?
Rest
Weight control
Regular low inpack excercise, hydrotherapy
NSAID
Nutraceuticals, chondroprotective drugs
Preventative surgical treatment?
TPO - tripple pelvic osteotomy
DPO - Double pelvic osteotomy
Pubic symphyiodesis
What patients can be included or excluded for a TPO?
What is the outcome?
TPO - tripple pelvic osteotomy
Only young patients (<9m) without secondary (OA) changes, and an angle for eduction <30 degrees and >10 degree subluxation
Good, excellent result in 76-92% of cases
What is a DPO? Compared to a TPO?
Double pelvic osteotomy - bilateral operation
Most favourable prognosis in patients having minimal degenerative changes, and angle reduction >45 degrees and angle of subluxation <15 degrees
What is pubic symphysiodesis? Patient inclusion criteria?
(Juvenile) Pubic symphysiodesis - electrocautery is used to damage the pubic symphysis in young puppies, causing altered pelvic development.
Patients must be younger than 16w (max 18w in giant breeds)
Patients MUST be neutered due to reduced pelvic inlet!
Salvage procedures for HD?
FHNE - femoral head and neck exision/ostectomy
THR - Total hip replacement
Other treatments of note for HD?
1) Pectineal myectomy - removing part/all of pectineus - procedure outdated, unjustified
2) Intertrochanteric osteotomy - no longer recommended
3) DARthroplasty - corticancellous bone graft to form a “shelf” - largely unproven procedure
How does a FHNE work?
Surgical removal of femoral head and part of next - remove direct skeletal contact -> “pseudoarthrosis” - “false joint”.
Advantages of FHNE?
1) Relatively simple, straightforward procedure
2) Minimal costs compared with alternatives
3) Low risk (peri- and post op)
4) Minimal post-op rest needed
5) A treatment option for many problems with the hip joint
6) Minimally veterinary follow up (does require some hydro/physio)
Disadvantages of FHNE?
1) Limb function will not be normal - a degree of lameness will be permanent
2) Muscle atrophy will persist (to a degree)
3) Some may have discomfort on full hip extension
4) Correct surgical cut is essential
5) excellent post-op rehabilitation needed
6) Salvage procedure - no turning back!
Indications for FHNE?
1) Hip pain/lameness - unrespinsive to conservative treatment (HD, OA)
2) Chronic hip luxation, non-reducible luxation, significant articular damage
3) non-repairable/chronic femoral head fracture, femoral neck fracture, slippet capital physeal fractures
4) non repairable acetabular fractures
5) Legg Calve Perthes
6) Septic hip unresponsive to medical management
7) Neoplasia fo the femoral head
8) Failure of a previous surgery (open hip luxation repair, THR)
Contraindications to FHNE?
When there is no hip pain on examination or conservative treatment has not been fully explored.
Wherever a THR is a good and realistic option.
What are the characteristics of first-generation total hip replacements?
- limited bone-bed preparation
- unplugged femur
- stiff, doughy cement introduced by hand
- digital pressurisation
- hand mixing of cement
What are the characteristics of second-generation total hip replacements?
- bone-bed preparation (bulb syringe irrigation/drying)
- distal cement restrictor (bone/plastic)
- retrograde cement application via cement gun
- femoral and acetabular cement pressurisation
- open atmosphere cement mixing by hand
What are the characteristics of third-generation total hip replacements?
- thorough bone-bed preparation (pulsatile lavage)
- improved distal cement restrictor
- retrograde cement application via cement gun
- femoral pressuriser, acetabular pressuriser
- vacuum mixing/centrifugation of bone cement, stem centralizers/cement spacers
what are the two main mechamisms of cementless total hip replacement?
1) Implants press-fitted into the bone
2) implants secured by screws
What approach to total hip replacement has the lowest complication rate based on retrospective studies?
The hybrid technique - with cemented femoral prothesis with cementless cup
What options are available for small dogs and cats for total hip replacement?
Biomedic micro and nano total hip replacement
Which is the most common type of hip luxation?
craniodorsal
What are the main stabilizers of the hip joint and how many must be injured for a hip luxation to occur?
Joint capsule
Round ligament
Acetabular rim
At least two
What is the clinical presentation of hip luxation patients?
Craniodorsal luxations -> shortened limb, hold leg adducted, externally rotated
What will be noted on clinical exam with hip luxation?
Assymetry on pelvic examination
Palpation: Greater trochanter - ichiatic tuberosity and dorsal ilial wing does NOT form a triangle (as it normally should)
What diagnostic tests can be done clinically to increase suspicion of a hip luxation?
Palpation - not a triangle
Thumb displacement test - thumb pressed firmly into the depression between the greater trochanter and the ischial tuberosity - if displaced when limb rotated externally -> NOT luxated
What image diagnostics are required for diagnosis of hip luxation?
VD and lateral XR
What should also be assessed on XR when diagnosing hip luxation?
Concurrent injuries - dorsal acetabular rim damage and HD -> affect surgical success
What is the success rate of closed reduction in cats and dogs?
Successrate:
50% in dogs
60% in cats
What are the indications of closed reduction?
Always closed reduction first - if there is not significant bony damage on radiographs
Indications of surgery with hip luxation?
Significant bony damage
Lack of stability, reluxation
Bilateral luxation
Other orthopaedic trauma in another limb
Which type of sling is indicated for what type of luxation?
Craniodorsal - Ehmer sling
Caudoventral - Hobbles
What surgical options are there for hip luxations?
1) Capsulorrhapy - can be combined
2) Iliofemoral suture (not ventral lux!)
3) Modified Knowles Toggle (all directions, can cause articular surface damage)
Is hip dysplasia a biphasic disease?
No. It was previously thought, bud HD is a monophasic disease
Differential diagnosis of CHRONIC pelvic limb lameness
in skeletally IMMATURE animals?
1: Avascular necrosis of the femoral head
2: Slipped capital femoral epiphysis
3: Panosteitis
4: Patellar luxation
5: Cranial cruciate ligament avulsion
6: Cranial cruciate ligament disease
7: Stifle OC(D)
8: Septic arthritis
9: Spinal disorders
10: Myopathies
11: Myasthenia gravis
Differential diagnosis of CHRONIC pelvic limb lameness in skeletally MATURE animals?
1: Cranial cruciate ligament disease
2: Patellar luxation
3: Lumbosacral disease
4: Other spinal disorders
5: Common calcanean tendinopathy
6: Septic arthritis
7: Myopathies
