57. Pelvic Fractures

Question 1

Optimal time to repair pelvic fx

Answer 1

Pelvic fx (in comparison w long bone fx) are time dep—best completed win 7-10 days

Question 2

Pelvic malunion and narrowing of what percent lead to constipation/obstipation

Answer 2

50% or greater (particular concern for cat—subtotal colectomy)

Question 3

Muscle attachments of origin at the ischium (ischiatic tuberosity)

Answer 3

Ischiatic tuberosity (site of origin)SemimembranosusSemitendinosusBiceps femorisIschium–Adductor musclesProne to avulsions that may require repair

Question 4

Most common ilial fx

Answer 4

Long oblique mid body fx (cranioventral to caudodorsal)caudal fragment is usually displaced medially and cranially (pelvic narrowing, injury to LS trunk)

Question 5

Surgery approach to ilium/ ilial fx

Answer 5

Lateral approach w “gluteal roll” up for lateral plate; 3 methods of reduction#1 Bone forceps on cd fragment (or greater trochanter) w lateral traction #2 Place cd portion of plate first (place screws cd to cr)#3 Use bone forceps and rotational movement to counteract oblique fragments (sliding technique)Caution: LS trunk–Sciatic n

Question 6

Surgery repair options for ilial fx

Answer 6

1. Bone plates: lateral (most common), ventral (tension surface; may decrease screw pull out in dogs), or dorsal (cats–more bone purchase) 2. Lag screws3. ESF (uncommon)

Question 7

Lateral plating technique/principals for ilial fx

Answer 7

At least 3 screws cr and cd1-2 cranial screws penetrate sacral wing w/o going into canal (cranial prone to pull out due to thin, soft bone)Good plate contouring (twist)2.7 mm small2.7-3.5mm med-lgMay also utilize lag screws (2-3) placed ventral to dorsal

Question 8

Conclusion of Vet surgery in 2009 Langley Hobbs et al Dorsal vs lateral plating in cat ilial fx

Answer 8

Lateral vs dorsal plateDorsal plate position in cats seemed to help reduce screw loosening at 4-6 wk post opMore screws available (7 vs 6), better bone purchase (89 vs 33 mm), sign less pelvic narrowingLateral plate >45% pelvic narrowing led to constipation

Question 9

percentage/location of acetabulum that carries majority of weight

Answer 9

Cranial 2/3 of acetabulum carries most of the weight bearing forces

Question 10

Historical long term outcome of nonsx fx of caudal acetabulum fractures

Answer 10

1988 JAVMA Boudrieau et al 15 casesSecondary arthritis worsens w nonsx tx based on rads in 13/15 dogs12/15 decr ROM7/15 lameUnsatisfactory results

Question 11

Surgery repair options for acetabulum fx

Answer 11

Dorsal approach w Internal fixation to dorsal acetabulum + osteotomy of greater trochanterBone forceps on ischium or separate approach to ischiatic table w cd retraction w Kern. maintain reduction manually, KWire, bone forceps, interfrag wire/screws–Bone plate (straight, recon, acetabular, oblique angle plates, SOP, other locking plates)–lag screws (if oblique fx)– plate w interfrag screws/wire–plate w PMMA luting (vet surgery 2002 D Lewis–stronger/stiffer vs wo PMMA)–combo screws, pins, wire, PMMASalvage (if severe comminution or severe medial wall fx w persistent femoral head lux)–FHO–partial reconstruction w THR planned after healing–amputationCAUTION: sciatic nerve near/dorsal to ischiatic notch

Question 12

Bone plate principles for acetabulum repair

Answer 12

Good contour after perfect anatomical reductionIdeally 3 screws cr and cd (often limited to 2 screws caudally)Direct screws away from articular cartilage

Question 13

Prognosis following internal fixation w bone plate for acetabular fx

Answer 13

GoodHistorically 83% had occasional to no clinical lameness (1988 ref)

Question 14

Most common cause of sciatic nerve injury in dogs according to vet surgery 2007

Answer 14

Vet surgery 2007 Forterre et al Iatrogenic injury during acetabular fx repair

Question 15

Percentage of dogs with unilateral vs bilateral SI luxation

Answer 15

Historical (1985 Vet Surgery Decamp)77% unilateral23% bilateral85% had severe ortho injury to disable both hindlimbs Caution: sacral nerve root & LS trunk injury

Question 16

Approaches described for SI repair

Answer 16

Dorsal* ( can visualize sacral wing )Ventral ( no direct view of sacral wing)MI fluoroscopy

Question 17

Methods of stabilization for SI repair

Answer 17

–Lag screw fixation w 1-2 screws**One screw should be 60% length of sacral body for max strength NOT WIDELY USED–trans iliosacral rods–trans ilial pins– tension band & wire

Question 18

Location of the drill hole into the sacrum during SI repair

Answer 18

40% from the ventral aspect and just caudal to an imaginary line drawn from dorsocranial to ventral in the sacral wing (1 cm^2 area)ORPalpate the cranial sacral notch, just caudal to the notch**different in CATS–just cranial to the C shaped cartilage (do not use cranial sacral notch)

Question 19

Prognosis w SI screws for SI lux repair according to Tonks, Tomilson et al in Vet Surgery 2008

Answer 19

24 cases lag screw–mean screw depth 64% w only 8.3% screw looseningLoosened fixation does not mean poor functional result It means loss of reduction and slight decrease in pelvic canal diameter

Question 20

Surgical repair for sacral fractures

Answer 20

screw placement (open vs closed with fluoroscopy approaches)lag screw placement based on fractured area (not same landmarks for SI repair

Question 21

Repair options for avulsion fractures of the ischiatic tuberosity

Answer 21

Lag screwsPins/wireCAUTION SCIATIC NERVE