Ch 56 Pelvis fractures Flashcards

Question

sx options for acetabular fracture (4)

Answer 1

- **Bone plate** fixation applied to the dorsal surface > Curved acetabular, straight, reconstruction, and “T” or “L” plates - Comminuted acetabular fractures may require a longer plate than the acetabular plate - **Locking plates** with locking screws > aid in maintaining reduction because contour does not have to be perfect, no advnatge in strength - **screws placed in lag** fashion - **composite**: K-wires, screws, orthopedic wire (18 or 20 g), and PMMA (PROS: no need contouring, all # types, mechanically strong) - excessive volume of cement may cause interference with the sciatic nerve or hip joint Careful contouring of the bone plate is essential to maintain reduction of the articular surface | Plate luting with PMMA way of artificially improving the fit

Answer 2

generally very good! - 83% occassional or no lameness - 83% reduced mid-thigh circumference DJD of varying severity was observed. Sciatic nerve iatrogenic damage occurring during reduction and stabilization. Loose or broken implants were uncommon.

Answer 3

1. oblique iliac fracture is widely spaced from the acetabular fracture, allows several possible methods of fixation using one or two plates 2. comminuted iliac fracture is located in close proximity to a comminuted acetabular fracture, often characterized by a large triangular iliac/cranial acetabular fragment - requires combined gluteal roll-up and dorsal open surgical approach - Widely spaced: iliac fracture is often reduced and plated first - comminuted: triangular fragment is first reduced to the proximal ilium, kwire/lag srews for interfragmentary fixation of smaller fragments, caudal acetabular fragment is then reduced, consider single, long, straight plate can be used as primary fixation - recon plates not strong enought for large dogs

Answer 4

23% in dogs 18% in cats

Answer 5

- iliac wing in sacroiliac luxation usually occurs cranial and slightly dorsal to the sacrum - more severe displacement may occur during the recovery period - ischial and pubic fractures are frequently present - caudal hemipelvis displaces medially and compromises the diameter of the pelvic canal - ventrodorsal radiograph, the medial wall of the iliac body should transition smoothly in a gentle curve with the caudal aspect of the sacral wing - 85% have severe orthopedic injuries that disable both pelvic limbs Ex - severe weight-bearing or non–weight-bearing lameness - pain upon palpation of the joint or when attempting to stand. - Sacral nerve roots and the lumbosacral trunk > urinary bladder, anal sphincter, and sciatic nerve - STUDY: 81% of the cases had good functional neurologic recovery within 16 weeks

Answer 6

selected for cases that have severe pain or displacement that compromises the pelvic canal - conservative treatment often results in prolonged cage rest, recumbency, or discomfort - pelvic # repaired before the sacroiliac luxation (though implants may obscure the view of the sacral body with fluoroscopy) - dorsal approach (ventral possible) - Where available, intraoperative fluoroscopy - largest screws maximizes sacroiliac repair strength, and penetration 60% width of the sacrum minimize postop loosening

Answer 7

Lag screw Transiliosacral rod or screw Transilial pinning Pin and tension band Ventral screw placement

Answer 8

- drill hole in the sacral wing is made exactly perpendicular to the table - sacral wing surface will not be exactly parallel to the table > tilted approximately 10 degrees inward dorsally Inserted at 100 +/- 4.7 degrees in dogs 97 +/- 6.9 degrees in cats

Answer 9

- iliac glide hole is located by palpating the joint surface on the medial side of the ilium. - A prominence may be palpated on the medial joint surface of the adult dog - Screw length is determined by glide hole and the sacral wing hole or determined presurgically on appropriately calibrated preoperative radiographs - Bilateral sacroiliac repairs may be completed with screw fixation, in lag fashion, from each side - >> alternative: use an aiming device or fluoroscopy to drill 100% across the sacral body and place a single long trans-iliosacral screw or a rod - Fluoroscopy can greatly aid in the placement, Adequate positioning of the animal is essential (confirming the superposition of the lumbar transverse processes) small K- wire inserted across the sacroiliac joint, keyhole incision through middle gluteal muscle, hole is drilled to an appropriate depth, based on preoperative planning

Answer 10

2.0/2.7mm cats and small dogs 3.5/4.0mm for medium dogs 4.5/6.5mm for large dogs

Answer 11

Less than 60% of sacral width, 38% loosening More than 60% width, 7% loosening

Answer 12

- ventral to the sacral body - premature ventral exit of the sacral wing - cranial placement into IVD of L7-S1 - dorsal into the spinal canal (cauda equina) often result in short, shallow screw placements in the sacral wing and often lead to high rates of loosened fixation | area for correct screw position in an average large dog ~ 1 cm2

Answer 13

newer case series - mean screw depth of 79% sacral width was achieved, no loosened fixations were observed - 64% of sacral width was achieved, and 8.3% had loosened screws on follow-up radiographs - studies validate the concept that adequate screw depth in the sacral body is important for long-term stable Note that loosened fixation does not automatically lead to poor functional results

Answer 14

- strict rest for 4-8 weeks can have good clinical outcomes and high owner satisfaction (stecyk 2021, 17 dogs) pursued in patients without significant pelvic canal collapse, with minimal SI joint displacement and minimal concurrent orthopedic injury, or in circumstances of financial or patient constraints.

Answer 15

Abaxial - all fractures located lateral to the sacral foramina + spinous processes Axial - all fractures medial to the sacral foramina and ventral to the spinous processes. - more likely to have associated neurologic deficits. Type I: Alar Type II: Foraminal Type III: Transverse Type IV: Avulsion Type V: Comminuted | compared with SI, extreme pain and neurologic deficits are more common

Answer 16

- 69% have neuro dysfunction - 43% pelvic limbs (decreased CP or deep pain lateral aspect of the paw) - 28% to 34% perineal sensation deficit, loss of anal tone, and urinary tract deficits - 28% Tail denervation Euthanasia was performed in 5 of 23 dogs with sacral fracture, but of the remaining dogs had good outcomes

Answer 17

- screw, deeply seated in the sacral body in lag fashion - dorsal approach - fragment is usually attached to the iliac wing, and so sacral wing surface anatomy is irrelevant to screw location for this procedure. - open surgical approach vs closed fluoro -

Answer 18

no studies have been conducted to compare results of conservative versus surgical - dogs respond well to surgical stabilization with rapid reduction of pain and restoration of limb function - Kirschner wires used in combination with the lagged screws often loosened; therefore, their use cannot be recommended

Answer 19

Interfragmentary wire Plates Pin and tension band Lag screws

Answer 20

indications: - facilitate the repair of other pelvic fractures in an attempt to decrease the risk of pelvic collapse in cats - to decrease postoperative pain - in cases of traumatic ventral abdominal hernia to provide an anchor point for prepubic tendon - pain or severe displacement caused by the pull of the hamstring muscles on ischium

Answer 21

polytrauma patients that require significant effort in nursing care - analgesic, antiinflammatory drugs, and antibiotic medications - epidural catheter > spinal/sacral fracture and the presence of neurologic deficits are absolute and relative contraindications - bilateral injuries often have difficulty standing - Frequent baths, clean bedding, and good padding - Standing is encouraged early, recumbency care as required (promote circulation and prevent decubital ulceration of the skin) - Expression of the urinary bladder or indwelling catheterization - Stool softeners may be used to ease defecation - short leash walks for 1 to 2 months - Radiographs should be taken on a regular basis - healed within 6 to 8 weeks. - physio

Answer 22

2 short 3.5mm cortical screws spanning ~23% sacral body width → higher peak load, yield load and stiffness vs single long lag screw - placed with 3D-printed drill guide - no difference in positional or lag screw placement for short screws foraminal impingement 3 samples (12.5%) shorter > decrease the risk of injury to sensitive surrounding anatomy. 2 screws: greater resistance to rotational forces and an increased bone-implant interface providing additive resistance to bending and shear

Answer 23

Defining a safe corridor for trans-iliac pin placement in cats cats between 2.0 and 5.5 kg. A 1.2-mm pin > mid-iliac wing start point. more dorsal start point > 2.0-mm pin if correctly aligned to the sacrum. dorsal start point = 2 mm from most dorsal aspect particularly where a fluoroscopy-guided surgery cannot be performed. Safer> larger area for placement and the more distant to the vertebral canal and nervous tissue iliac wing compression achieved by trans-iliac implants is enough to reduce hemipelvis displacement healing is through fibrosis and therefore may not require the same stability as bone fracture heal

Answer 24

Likert scores that assessed the ease of the procedure were significantly greater (P = .04) and the incision length was significantly shorter (P = .016) in the 3-DP drill guide group compared with the freehand group. The time of the procedure, the number of attempts to obtain accurate Kirschner wire placement, and fluoroscopy images did not differ (P > .05) between application groups. Instead of freehand manipulation of a small drill sleeve, manipulation of a radiolucent 3-DP drill guide with multiple drill holes would seem simpler.

Answer 25

retrospective, Locking compression plates were used as a sole method of fixation in 11/15 cases, while with other ancillary implants in 4/15 cases. There were two minor complications > single screw backing out At the last clinical follow-up (median 46 days: 38–88 days 11/15 cats exhibited postoperative neuropraxia > All of our patients recovered function by the time of the first follow-up examination The stabilization of acetabular fractures with locking implants has recently been described in 17 dogs,18 while previous reports in cats only included a total of 4 cases.5,16

Answer 26

double 2.3mm headless compression screw vs 3.5mm cortical screw - more resistance to rotation, applied fluoro-guided with no vertabral or ventral sacral foramen breach

Answer 27

Locking plates/screws act as a single beam construct that transfers bending forces to compressive stress at the screw–bone interface. This construct requires higher forces in order to cause failure, in contrast with nonlocking constructs, where loosening of a single screw can initiate serial screw loosening. > shearing loads associated with nonlocking constructs, which consistently led to screw pullout and construct failure.

Answer 28

Retrospective clinical study. Animals: Eleven cats. Screw migration was not observed. PCDR and HCWR measured on postoperative radiographs indicated successful restoration of the pelvic canal width. Owners reported an excellent long-term functional outcome Sacroiliac craniocaudal reduction is considered optimal when it is >90% Cannulated cortical screws showed higher fatigue resistance compared to noncannulated screws, with fatigue being mainly dependent on the screw body diameter. Partially threaded screws allow the articular surfaces of the sacrum and ilium to be compressed to each other, increasing the stability of the fixation Moreover, a cadaveric study in dogs reported that ionizing radiation absorbed by surgeons is minimal during percutaneous fluoroscopically guided lag screw fixation of SIL should be 40% cortical bone diameter | AO recommendation, screw diameter

Answer 29

Ex vivo biomechanical. lateral plate repairs cats. ALPs 5, 6.5, LCP, Fixin and DCP in cycles to failure - ALPS 6.5 = LCP = Fixin > DCP and ALPS 5 - ALPS 5 failure by plate size rather than plate-screw interface - non-locking screws failed by loosening, locking screws failed by bone slicing The screw working length has significant effects on screw pull-out forces; the short cortical screws in our DCP specimens were therefore more susceptible to loosening.

Answer 30

Blinded, randomized, prospective ex vivo study. 3D-printed drill guide for sacral hole → increased accuracy for SI screw - drill end points improved → no inappropriate drill exit - press-fit of drills reportedly challenging - pre-operative planning on CT MPR → similar accuracy to drill guide - drill guide placement required complete displacement of ipsilateral ilial wing One recent study revealed higher accuracy in screw placement using fluoroscopy (92%) versus open reduction with internal fixation (58%)

Answer 31

Seventeen cats met the inclusion criteria, and 13 owners completed the questionnaire. Twelve cats had an excellent outcome, with no difficulty performing normal activities. One cat had a good outcome, with slight or occasional difficulty performing normal activities. Sacroiliac joint ankylosis and degenerative joint disease are thought to develop after conservative management of SILF indications for conservative management of SILF are - being ambulatory, - displacement of <50% of the joint surface, - minimal pain or instability, - absence of concurrent fractures of the weightbearing axis, - absence of neurological deficits - <45% narrowing of the pelvic canal

Answer 32

Cadavers from 10 adult dogs, A distraction of at least 2 cm was obtained Intraoperative skeletal traction provides a useful and reliable tool for the reduction in experimental oblique and transverse iliac fractures in dogs. There were strong correlations between body weight and the force required studies in human medicine have shown that the duration of traction is a critical feature because traction devices have been associated with iatrogenic damage.22 Excessive traction is associated with complications such as impairment of vascular and nerve integrity

Answer 33

Retrospective study. 59 SOP vs non-locking plates → higher implant failure with non-locking implants - 29% overall failure > 17/18 non-locking vs 1/18 SOP NLS (20x more likely) in short-term. If nonlocking fixation failure develops, the mode of failure is usually screw loosening or pullout, rather than plate or screw breakage. mixed results: two cadaveric studies did not show any difference biomechanically, clinical studies found a decrease in complications and screw loosening when locking plates were used double SOP plating versus single DCP > double SOP greater bending stiffness, bending strength, bending structural stiffness, and torsional stiffness locking dont rely on plate-to-bone friction to provide stability have been developed, and, consequently, eliminate the need for high shear load resistance at the screw-to-bone interface. 20,21,24,25 These systems provide more stable fracture repair, especially in poorer quality bone.2 In addition, diminished plate-to-bone contact in these systems minimizes the negative impact on local vascularity during fracture healing. | retro, not randomised, no objective outcomes, short-term

Answer 34

77 cats single vs double cuttable plate fixation of feline ilial fractures - implant failure (screw loosening) higher with single (14/29) vs double (6/48) plates - no difference in sacral index Screw loosening occurred in 45% of the SLP, compared to 13% double plate (increased screw purchase dt inc no.) Alternatively, single plating with locking implants or TPLO plates, dorsal plate The benefit of sacral screw engagement remains unclear. latereal plating associatedwith a high incidence (50–62%) of screw loosening when non-locking plates are used, | short term follow up, retrospective, clinical function unknown

Answer 35

The iliac fragments were fixed by a 2.7-mm lag screw (5/5 cases) and an additional 2 Kirschner wires 0.8mm (1/5 cases). bone decortication 4/5 cases or not 1/5 case The radiographic examination immediately postoperatively and 8 weeks postoperatively showed a mean pelvic canal enlargement of 20% (range 7–38%). Minor complication occurred in one case; this resolved 15 days postoperatively without any treatment. Complications and recurrence of obstipation did not occur during the final follow-up, ranging between 5 months and 1 year in any of these cases If clinical signs have been present for less than 6 months, widening the pelvic canal has been proposed as a treatment option for obstipation/megacolon, greater than 6 months, subtotal colectomy might be indicated The pelvic canal can be widened by revising the fracture malunion via ostectomy of impinging bone or corrective osteotomy and stabilization after correcting the pelvic canal narrowing, distraction of each hemipelvis after osteotomy of the entire pelvic symphysis is performed use of a single compression screw does not follow the AO23 principles of fracture management; however, the clinical results indicate that the screw positioned in this fashion gives sufficient stability to allow the healing of the osteotomy | more cases needed to deterimine success/risk

Answer 36

retrospective Locking Plate Canine Acetabular Fractures. 17. locking plate fixation (VetLOX, SOP and LCP) for canine acetabular fractures - overall good outcomes - complications: 9/17 mild sciatic neurapraxia, 2/17 longer term proprioceptive deficit - minor 2/18 screw loosening/breakage sole method of fixation in 10/18 acetabula, and as adjunctive fixation with other implants in 8/18 acetabula inaccurate fracture reduction and implant loosening were not fully avoided by use of locking implants but incidence was low.

Answer 37

Study design: Retrospective case study. Animals: Cats (n = 280). Twenty percent of cats did not survive to discharge. predictors of comorbidities and mortality in cats with pelvic fractures - mortality increased with fracture severity and mean number of concurrent body regions affected - each additional body system → 1.85x risk - bilateral injury → 27.6% mortality vs uni- 12.5% - neurological injury → reduced survival - no other individual body system associated euthanasia because of financial reasons > 50 (18%) cats in our study.

Answer 38

Twenty consecutive cats use of single transsacral screw and nut for bilateral SI luxation - VI instrumentation including aiming guide - reduction achieved in all cats → full function in all cats - tendency to widen pelvic canal diameter .All cats available at follow-up examination were able to walk without signs of discomfort unable to compare to other methods.

Answer 39

dorsal/lateral non-locking vs lateral locking vs lateral and dorsal non-locking plate constructs in feline ilial fracture gap model - double plate → higher stiffness and cycles to failure - single locking plate → more cycles to displacement than single non-locking - no screw loosening, locking lateral plate stronger than non-locking dorsal Locking implants extended fatigue life and resistance to screw loosening. Orthogonal plating offers a strong nonlocking alternative.

Answer 40

Retrospective study. Animals: Fifteen client-owned cats. – use of transiliosacral toggle suture (Arthrex mini-Tightrope > fiberwire) for bilateral SI luxation in cats - proposed to maintain motion at SI junction – benefit unknown - %reduction 88.1±11.2% on the right, 91±11.6% on the left - good functional outcome, pelvic canal width ratio 1.24±0.08 No major complication was reported sacral wing fracture

Answer 41

retrospective analysis dorsal brace construct consisting of paired transiliac locking plates would facilitate fracture healing non-ambulatory (n=8) or hindlimb lameness (n=4). Nine sacral fractures were considered Anderson type II and three Anderson type V. The plate fixation was augmented with additional surgical stabilisation in 11 cases. Eleven patients were ambulatory at discharge and all cases healed uneventfully without major surgical or postoperative complications implant-holding properties of the sacrum are poor due to thin cortices, whilst regional neurovascular structures make iatrogenic injury a significant risk. plate had only one locking screw engaging the iliac wing. It has not been biomechanically elucidated

Answer 42

pelvic osteotomy (with crank plate) and ventral fixation of the ischium using cortical screws and polymethylmethacrylate (PMMA) Postoperative improvements in constipation and defecatory difficulty were noted in all cases. The postoperative SI was significantly higher without implant failures. One case developed necrosis of the pubic surgical wound

Answer 43

Retrospective. n = 67 one lag and one positional. The mean sacral purchase for lag and positional screws were 46% and 31% Clinical follow up: 42/67 cats. full function in 81% Screw failure (4.7%) 1 canal penetration. Pelvic canal diameter was maintained in all cases. Conclusion: Excellent functional and radiographic outcomes

Answer 44

Retrospective. Client-owned cats (n = 125). No intraoperative complications no change in pelvic canal width observed Implant loosening radiographs in (13%) mean time to frame removal 37 ± 9 days. No long-term complications Long-term mobility score was 95 and median lameness was 0 provides good outcomes 1.6 mm diameter negative profile partially threaded pins. A three-pin frame was used for all SI cases. advantages - pins placed with almost limitless versatility to accommodate # configuration - transfixion pins as levers and in reduction without the need for reduction forceps comminuted acetabular > degree of fibro-osseus union expected at the fracture site. but still good functional outcomes .... smooth portion of the pin now acting as a reduction guide, reduction of the sacroiliac luxation was completed by sliding the ilial wing along the pin by axially applied compression over the ilial wings. The authors have termed this the “pin anchor slide technique” (PAST).

Ch 56 Pelvis fractures Flashcards

(70 cards)