60. SX managment for HD

Question 1

what bones make up the canine pelvis

Answer 1

paired os coxae (ilium, ischium, pubis, acetabulum)sacrumfirst caudal vertebra

Question 2

when does the femoral head ossify

Answer 2

8 weeks of age

Question 3

when do the bones of the os coxae fuse

Answer 3

12 weeks of ageilium, ischium, pubis, acetabulum

Question 4

T/Fcranial border of the pubis is the insertion of the prepubic tendon which is made up of all the fascia of the abdominal wall musculature

Answer 4

FALSEDOES NOT INCLUDE TRANSVERSUS ABDOMINIS MUSCLE

Question 5

what muscle originates at the iliopectineal eminence

Answer 5

pectineus muscle

Question 6

T/Facetabular anteversion leads to coxofemoral luxation

Answer 6

TRUEacetabulum is normally directed slightly caudally in relation to midline–acetabular retroversion

Question 7

normal angle of femoral neck anteversion

Answer 7

27 degrees (ranges 12-40)

Question 8

T/Ffemoral retroversion leads to coxofemoral luxation follow THR

Answer 8

TRUEfemoral is normally 27 anteversion

Question 9

muscles that insert to the greater trochanter, lesser trochanter and third trochanter

Answer 9

greater—middle and deep gluteals, piriformis musclelesser–iliopsoas musclethird–superficial gluteal

Question 10

options for juvenile or skeletally immature dogs for treatment of HD

Answer 10

1. juvenile pubic symphodesis (JPS)–12-16 weeks2. triple or double pelvic osteotomy (TPO/DPO)– < 10 months with no OA with min femoral head coverage3. FHO

Question 11

Juvenile pubic symphodesis

Answer 11

12-16 weeks of age (Ineffective at 22 weeks of age)–ventral midline/ CASTRATE/OHE–cautery thermal destruction 40 W 10-30 sec 2-3 mm cranial 1/3 pubis –closes growth plates and results in shortened pubic bones and increases ventral rotation of acetabulum (ventroversion) to increase femoral head coverage–decr OA at 2 yrs of age when performed early, improved 10-15 degrees by 6 weeks; also no difference seen in JPS vs TPO treated

Question 12

procedures for TPO

Answer 12

–transverse incision over pectineus muscle–transect from iliopubic eminence, pubic osteotomy 1 cm wrongers (save as graft) CAUTION obturator n and don’t go into medial acetabular wall–ischiatic osteotomy–horizontal or vertical incision, elevate int obturator muscles dorsal and Semi muscles ventral; Gigli, osteotome or saw aim lateral foramen; can pre drill holes for wire–lateral approach to ilium with gluteal roll up; sagittal saw just caudal to caudal dorsal iliac crest; secure plate to caudal segment first, then cancellous screws on cranial segment

Question 13

ways to decrease screw loosening/pullout with pelvic osteotomy plates

Answer 13

1. cancellous screws cranially2. purchase sacrum3. lockin plate (self tapping screws decr risk pullout)4. hemicerclage in ischial segment to decr movement5. addition of ventral ilial plate6. cage restrictionhemi cerclage into TPO plate had NO effect on screw loosening

Question 14

complication with pelvic osteotomies

Answer 14

1. sciatic nerve damage2. obturator nerve damage3. pelvic narrowing–constipation, dysuria4. loosening of cranial screws 62%5. overrotation and impingement of femoral neck; decr abduction6. relux7. progression OA

Question 15

historical documented outcome in small dogs vs large dog with FHO

Answer 15

small dogs < 17 kg did better than larger dogsOff et al VCOT 2010kinematic/kinetic data should functional deficits in small and large dogs38% good function42% poor functionbut owners were >90% satisfied with results

Question 16

low vs high osteotomy cuts for CFX/BFX THR implants

Answer 16

CFX favors lower osteotomy cuts to decr varus stem placementBFX favors high osteotomy cuts

Question 17

amount of antibiotic in PMMA cement

Answer 17

1 gm cefazolin: 40 gm PMMA

Question 18

Types of cement mixing techniques

Answer 18

1. vaccum mixing–reduces porosity, increases fatigue strength and evacuates fumes2. cement injection3. pressurized–forces cement into small irregularities to max cement bone interface

Question 19

direction of the ace tabular implant in THR

Answer 19

RETROVERTED 10-20 degrees (directed caudally)CLOSED 5-10 degrees

Question 20

T/FPulsatile lavage and suction remove bone and blood fragments after drill, ream, and broaching therefore improving push out strength of cement 185%

Answer 20

TRUE

Question 21

what is the primary cause of craniodorsal laxations following CFX THR

Answer 21

femoral stem anteversion–crdorsal luxfemoral stem retroversion–cdventral lux

Question 22

complication rate with Kyon–Zurich and Biomedtrix BFX

Answer 22

Kyon has a higher complication rate 17%

Question 23

list complications of THR

Answer 23

1. incisional 2. Aseptic loosening–more so w CFX3. luxation–up to 2 weeks post op4. infection–moreso with CFX5. femoral fracture–more so with BFX 3%6. Subsidence and pistoning–moreso with BFX (normal 2-5 mm)7. neurapraxia8. PTE

Question 24

when performing pubic osteotomy for TPO what structures must be protected

Answer 24

1. medial acetabular wall2. obturator nerve3. medial circumflex femoral vessels

Question 25

complication range for CFX

Answer 25

12-13% (17% Kyon)

Question 26

aseptic loosening complication for CFX

Answer 26

common-likely to occur at cement bone interfaceresult of accelerate bone resorption adjacent to implant in response to metal, plastic or cement

Question 27

two ways to removal femoral stem implant

Answer 27

1. lateral window in lateral femoral cortex2. linear lateral osteotomy and drive out with proximally directed force

Question 28

treatment for post op luxation with THR

Answer 28

1. reposition malpositioned implants2. prosthetic capsulorrhapy repair/soft tissue techniques3. FHO/remove implant4. TPO

Question 29

T/Fincreasing femoral neck decrease post op luxation

Answer 29

TRUElong neck decr luxshort neck incr lux

Question 30

radiographic appearance of infected THR compared to aseptic loosening

Answer 30

initially they may look similar (lytic around implant) but infection is associated with greater periosteal reaction, increased bone lysis, sclerosis, cloacae and draining tracts

Question 31

what is subsidence and pistoning

Answer 31

subsidence is “settling” or distal displacement; 5 mm may risk luxationpistoning is when the bone fails to incorporate into stem and stem moves proximal and distal with weight bearing

Question 32

Lister, Roush et al coxofemoral dennervation

Answer 32

relief of hip pain sciatic n innervates CAUDOLATERAL jt capsulecranial gluteal n innervates CRANIOLATERAL jt capsuleuse bone curette or elevator to scrape lateral periosteum cranial to acetabulum (in area of rectus femoris muscle origin) to dorsal of the acetabulumno change in fore plate data 24 weeks post op

Question 33

other discarded therapies for hip dysplasia

Answer 33

1. dennervation of coxofemoral jt2. intertrochanteric osteotomy (medial closing wedge and plate)3. pectineus myectomy 4. shelf arthroplastyNO results show improvement and progression of OA is likely to continue–not recommended