60. SX managment for HD Flashcards
what bones make up the canine pelvis
paired os coxae (ilium, ischium, pubis, acetabulum)sacrumfirst caudal vertebra
when does the femoral head ossify
8 weeks of age
when do the bones of the os coxae fuse
12 weeks of ageilium, ischium, pubis, acetabulum
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
FALSEDOES NOT INCLUDE TRANSVERSUS ABDOMINIS MUSCLE
what muscle originates at the iliopectineal eminence
pectineus muscle
T/Facetabular anteversion leads to coxofemoral luxation
TRUEacetabulum is normally directed slightly caudally in relation to midline–acetabular retroversion
normal angle of femoral neck anteversion
27 degrees (ranges 12-40)
T/Ffemoral retroversion leads to coxofemoral luxation follow THR
TRUEfemoral is normally 27 anteversion
muscles that insert to the greater trochanter, lesser trochanter and third trochanter
greater—middle and deep gluteals, piriformis musclelesser–iliopsoas musclethird–superficial gluteal
options for juvenile or skeletally immature dogs for treatment of HD
- 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
Juvenile pubic symphodesis
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
procedures for TPO
–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
ways to decrease screw loosening/pullout with pelvic osteotomy plates
- 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
complication with pelvic osteotomies
- 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
historical documented outcome in small dogs vs large dog with FHO
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
low vs high osteotomy cuts for CFX/BFX THR implants
CFX favors lower osteotomy cuts to decr varus stem placementBFX favors high osteotomy cuts
amount of antibiotic in PMMA cement
1 gm cefazolin: 40 gm PMMA
Types of cement mixing techniques
- vaccum mixing–reduces porosity, increases fatigue strength and evacuates fumes2. cement injection3. pressurized–forces cement into small irregularities to max cement bone interface
direction of the ace tabular implant in THR
RETROVERTED 10-20 degrees (directed caudally)CLOSED 5-10 degrees
T/FPulsatile lavage and suction remove bone and blood fragments after drill, ream, and broaching therefore improving push out strength of cement 185%
TRUE
what is the primary cause of craniodorsal laxations following CFX THR
femoral stem anteversion–crdorsal luxfemoral stem retroversion–cdventral lux
complication rate with Kyon–Zurich and Biomedtrix BFX
Kyon has a higher complication rate 17%
list complications of THR
- 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
when performing pubic osteotomy for TPO what structures must be protected
- medial acetabular wall2. obturator nerve3. medial circumflex femoral vessels
complication range for CFX
12-13% (17% Kyon)
aseptic loosening complication for CFX
common-likely to occur at cement bone interfaceresult of accelerate bone resorption adjacent to implant in response to metal, plastic or cement
two ways to removal femoral stem implant
- lateral window in lateral femoral cortex2. linear lateral osteotomy and drive out with proximally directed force
treatment for post op luxation with THR
- reposition malpositioned implants2. prosthetic capsulorrhapy repair/soft tissue techniques3. FHO/remove implant4. TPO
T/Fincreasing femoral neck decrease post op luxation
TRUElong neck decr luxshort neck incr lux
radiographic appearance of infected THR compared to aseptic loosening
initially they may look similar (lytic around implant) but infection is associated with greater periosteal reaction, increased bone lysis, sclerosis, cloacae and draining tracts
what is subsidence and pistoning
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
Lister, Roush et al coxofemoral dennervation
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
other discarded therapies for hip dysplasia
- 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
