Ch. 38-41: Fracture Misc

Question 1

Schrock VCOT 2022

Outcomes and complications associated with acute gunshot fractures in cats and dogs

• MC fx location?
• % with extensive ST trauma?
• % with poor fracture outcome after sx?
• increased likelihood of poor outcome with what?

Answer 1

Report outcomes and complications of gunshot fractures
Poor outcome = death, major postop complication, or amputation of a limb

Results:
40% distal long bone > 26% proximal long bone > 15% maxillofacial > 12% vertebral column > 6% rib
45% had “extensive” soft tissue trauma

21 animals underwent orthopedic surgery
55% incurred poor fracture outcome

Increased likelihood of poor outcome when extensive soft tissue trauma at the fracture site was present

Poor outcomes reported:
7 amputations
3 osteomyelitis/SSI
4 delayed/non-unions

Conclusions:
Gunshot fractures have a poor outcome 54% of cases; worse if extensive soft tissue trauma

Question 2

Linder JVECC 2023

Ballistic trauma to the axial skeleton in 13 animals

• conclusion re: px and outcome?

Answer 2

Retrospective, multicenter observational study

12/13 animals survived to discharge; 1 animal was euthanized shortly after presentation.
Two animals had ophthalmic abnormalities, 9 animals had neurologic lesions, and 2 animals had no significant ophthalmic or neurologic deficits.

7 dogs underwent surgical intervention:
5 neurosurgical
1 enucleation
1 laparotomy
Median hospitalization time was 6 days with a range from 1 to 31 days.

Conclusions: Overall prognosis and outcome are variable and dependent on specific injury location and degree of injury.

Question 3

Salmelin VCOT 2023

Comparison of Trauma in Dogs due to Direct Motor Vehicle Collision or Fall from Open Pick-up Truck Bed during Transportation (2002-2020)

• diff between groups in % ortho trauma?
• ST injuries?
• Thoracic trauma?
• discharge?
• conclusions re: MVC? PTB?

Answer 3

Motor vehicle-related injuries can be subclassified as motor vehicle collision (MVC) or falling out of an open pickup truck bed (PTB)

Ortho Trauma: PTB (90%)&raquo_space; MVC (75%) [significant]
ST injuries were similar: PTB (70%) vs MCV (75%)
Thoracic Trauma: PTB (5%) &laquo_space;MVC (25%) [significant]
Abdominal Trauma: PTB (0%) &laquo_space;MVC (13%) [significant]
Surgery: PTB (7%)&raquo_space; MVC (50%) [significant]
Rate of discharge: PTB (95%)&raquo_space; MVC (85%) [significant]
Aftercare: More difficult in PTB (reported 76% difficulty)&raquo_space; MVC (34%) [significant]

Conclusions:
MVC and PTB incur different types of trauma
- PTB tends to be more orthopedic
- MVC tends to be more thoracoabdominal
- PTB has a better survival to discharge

Question 4

Castilla VCOT 2023

Long-Term Assessment of Bone Regeneration in Nonunion Fractures Treated with Compression- Resistant Matrix and Recombinant Human Bone Morphogenetic Protein-2(rhBMP-2) in Dogs

• what are BMPs?
• What do BMPs do in MSK system?
• BMP use?
• what do BMPs need? types?
• conclusion in their 6 cases?

Answer 4

Of nonunions in dogs, 60% are in the distal RU (likely due to reduced vascularity in toy breeds) and 25% in tibia
BMPs are multifunctional growth factors that play a important roles in embryogenesis and maintenance of adult tissue homeostasis
In skeletal system, BMPs promote new bone formation by stimulating differentiation of pluripotent MSCs into osteoprogenitor cells, osteoblasts and osteocytes
In VetMed, BMP has been used for treatment of nonunion long bone fractures, mandibular reconstruction and arthrodesis
Carriers are needed for optimal delivery and maintenance of BMP concentration at the treatment site
Four major categories of carrier materials include: inorganic materials, synthetic polymers, natural polymers and composites
Compression-resistant matrix (CRM): natural polymer composed of collagen sponge w/ embedded granules of hydroxyapatite and tricalcium phosphate

Study:
Prospective study of 6 dogs that had distal long bone fracture nonunions treated w/ fixation, CRM and rhBMP-2
CT scans were performed for quantitative measurements and compared to contralateral limbs

Results:
rhBMP-2 treated bones had higher density at the periphery and lower density in the center which is similar to the normal contralateral limb

Median density (entire cross section) in rhBMP-2 bones was similar to contralateral bone

Median cortical density rhBMP-2 was similar to contralateral bone

Median medullary density rhBMP-2 was 414 HU vs contralateral bone -45 HU (not significantly different)

All patients healed and were weight-bearing at 1 year follow-up (3 had good return to function, 3 acceptable pain-free)

Conclusions:
rhBMP-2 treated fractures were restored to normal architecture and density

Question 5

Cabassu VCOT 2019

MIPO using fracture reduction under the plate without intraop fluoroscopy to stabilize diaphyseal fractures of tibia and femur in dogs and cats

• differences in alignment and torsion?
• conclusion?

Answer 5

21 tibial and 20 femoral fractures stabilized (14 plate rod)

Mean postop operated tibial length 1.4% shorter; femur 2% shorter

No difference in tibial torsion noticed;
No significant difference in MMPTA, MMDTA, ALDFA, and femoral neck anteversion observed

5 cases (3 plate rod) needed immediate revision

Conclusion: MIPO with FRUP leads to acceptable alignment, but pin placement needs to be correct

Question 6

Von Pfeil Vet Sx 2020

Development of a novel fracture fragment stabilization system for minimally invasive osteosynthesis and in vitro comparison to traditional Kern bone reduction forceps

• what novel system?
• 3 findings?

Answer 6

develop and evaluate a novel fracture fragment stabilization system, the Sirius minimally invasive bone reduction handle system (SMH), in an artificial fracture model using MIO approach

The developed SMH consisted of modified Kern forceps connected with existing external skeletal fixation components.

The SMH was more difficult and took longer to assemble
SMH resulted in a smaller final fragment reduction gap
More surgical experience resulted in faster surgery times but was not correlated with final fracture gap formation.

Question 7

Mund VCOT 2023 PQ

Management of Feline Femoral , Tibial and Humeral Fractures Using a 3.5mm Titanium Interlocking Nail

• ILN provide what? subject to less what?
• Diff in AMI between ILN and plate?
• ILN they used?
• % complications? % major?
• comp higher in what bone?
• conclusions re nail?

Answer 7

• ILN provide rotation, axial, bending and compression stability in fracture repairs; positioned in the neutral axis of a long bone so the nail is subjected to less bending forces
• ILN has an AMI 4X > bone plate = greater rigidity
• Current ILN complication rates are b/w 6-25%
• Revision rates reported as 14%
  Screw malpositioning intraop reported in 0-38% of cats (commonly the most distal screws are affected)
  Postop complications include nail breakage and bending, screw breakage and bending, screw loosning, non-unions, delayed unions, infection, soft tissue injury, neurapraxia
• 67 cat fractures with 3.5mm titanium ILN-screws (Ti-6AI-4V)
• 16% complications
• Major complications in 12%:
  Screw breakage with fragment displacement (3/8), nail breakage (2/8), nail bending (1/8), screw loosening (1/8), non-union (1/8)
  7/8 major complications were in the femur (88%) and 1/8 were in the tibia (12%)
• Conclusions:
  Titanium ILN is feasible for repair of feline humerus, femur or tibia fractures
  Major complication rate was 12% with the femur having the highest risk of major complications (statistically significant)

Question 8

Mascellino VCOT 2023

A Retrospective Short-Term Evaluation Using a Polyaxial Plating System in 60 Small Animal Fractures

• what plate system?
• mean time to radiographic healing?
• % union?
• % comps?

Answer 8

Study:
Retrospective of 60 fracture repairs performed with Liberty Locking System (57 long bone, 3 axial)

Results:
Mean time to radiographic healing ~ 6 weeks (range 4-16)
Union was achieved in 100% of cases
5 complications (8%): 1 minor (superficial dehiscence), 4 major (3 had SSI and 1 had screw irritation of flexor tendons during RU repair and required explantation)

Conclusions:
LLS is amenable to fracture repair

Question 9

Mazdarani VCOT 2023

Ideal Anchor Points for Patellar Anti-rotational Sutures for Management of Medial Patellar Luxation in Dogs: A Radiographic Survey

• abnormalities associated with Patellar lux?
• what did they study?
• fabellar center had larger what?
• best fit circle compared to fabellar?
• conclusions re fabella? best fit circle?

Answer 9

Patellar luxations associated abnormalities: malalignment of quadriceps mechanism, CFJ conformation (abnormal angles of inclination and anteversion, decreased acetabular coverage, hip dysplasia), distal femoral torsion and angulation, medial deviation of the tibial crest, tightness/atrophy of the quadriceps muscles, shallow femoral trochlear groove, hypoplasia of the medial femoral condyle; occasionally, the cause is traumatic w/ femoropatellar instability occurring due to tearing or stretching of the parapatellar joint capsule and/or fascia

Soft tissue techniques for MPL: medial desmotomy, lateral imbrication, medial musculature release, patellar or tibial anti-rotational sutures
Patellar anti-rotational sutures –> creating a synthetic lateral femoropatellar ligament by anchoring the lateral fabella to the patella w/ a nonabsorbable suture; this is performed b/c the fabella has been assumed to be the center of the arc of rotation of the patella, such that the fabellopatellar suture would remain taut at all stifle angles

Study: Identify ideal anchor point for patellar anti-rotational sutures

Results:
- Fabellar center had a larger radii than a best-fit trochlear circle for most
- Best-fit circle radius was less varied than the fabellar center radius
- Significant differences were seen in location for centers of the best-fit circle and the fabella across all patient categories

Conclusions:
The fabella is not likely to be the best choice for anchoring a patellar antirotation suture
Use of the best-fit circle center to place a suture anchor should be preferred to maximize isometry during joint flexion and extension in small and large breeds

Question 10

Lloyd 2023 VCOT

The Effect of Location of a Unicortical Defect on the Mechanical Properties of Rabbit Tibiae: A Model of the Distal Jig Pin Hole in Tibial Plateau Levelling Osteotomy

difference in mid diaphysis jig pin vs distal diaphysis re:
- torque? stiffness?
- energy? angle?
- conclusions re distal jig placement?

Answer 10

Postop TPLO fractures reported from 0.02-9%, but it is not known what percent of these are due to jig pins holes which can fracture due to stress concentration under torsional and bending loads
TPLO jig
Proximal pin –> caudal to MCL
No consistent recommendations for distal jig pin - compared 3 groups:
1) intact
2) Mid-diaphysis (MD group)
3) Distal metaphysis (DM group)

All tibia fractured in a spiral configuration, with ALL fractures occurring only in the MD group (33% of MD tibia) and 0% of DM group
No differences noted b/w torque and stiffness amongst the 3 groups
Energy was reduced in the MD group relative to the intact tibia
Angle was also reduced in the MD group compared to the intact tibia

Conclusions:
Study suggests the distal jig pin should be placed in the distal metaphysis (in dogs) to have a lesser effect on the torsional properties of the tibia