Humeral Fractures

Question 1

Shipov, Vet Surg, 2015:

1. What sized IM pin is recommended for dogs 25-35kg?
2. Issue(s) associated with IM pins >45% the diameter of the medullary canal?
3. Issue(s) associated with IM pins <36% the diameter of the medullary canal?

Answer 1

Shipov, Vet Surg, 2015:

1. IM pins 36-45% (40%) of the medullary canal was recommended for dogs 25-35kg
2. IM pins >45% of the medullary canal diameter were associated with a high fracture rate and suboptimal exit point in the proximal humerus
3. IM 25-35% of the medullary canal diameter were associated with suboptimal exit points and blanching of the medial cortex of the medial epicondyle

Question 2

Guiot, Vet Surg, 2019:
Minimally invasive percutaneous medial plate-rod osteosynthesis

1. Rod-to-medullary canal ratio?
2. Plate-span ratio?

Answer 2

Guiot, Vet Surg, 2019:

1. Rod-to-medullary canal ratio was 30%
2. Plate-span ratio was 5.8

Question 3

Hurt, VCOT, 2014:
Unilateral and bilateral SOP plates for distal humeral metaphyseal fractures

1. Which construct had higher stiffness in axial loading and torsion?
2. Which construct had lower failure loads and lower ultimate strength?
3. Mechanisms of failure for unilateral vs bilateral SOP plate constructs?
4. It is recommended that a bicortical transcondylar screw be incorporated in the distal screw hole of the caudomedial plate when possible - true or false?

Answer 3

Hurt, VCOT, 2014:

1. Bilateral plate construct had higher stiffness
2. Bilateral plate construct had lower failure loads and lower ultimate strength despite having higher stiffness
3. Unilateral plate: failed by screw and plate bending and subsequent collapse of the lateral transcortex
   Bilateral plates: failed by screw pullout
4. True

Question 4

Coggeshall, Vet Surg, 2014:
IOHC treated with F2T2 screws vs cortical screws

1. Were mechanical properties superior in the isolated F2T2 screw or the isolated 4.5mm cortical screw?
2. Mechanism of failure for the F2T2 screw vs cortical screw in isolation?
3. Mechanism of failure for the applied F2T2 screw?
4. Any difference in mean stiffness, yield load and load at failure between humeri stabilized with the F2T2 screw vs the cortical screw?

Answer 4

Coggeshall, Vet Surg, 2014:

1. Mechanical properties were superior in the F2T2 screw
2. F2T2 screws failed by fracture through the fenestration in the midsection of the implant, whereas the cortical screws failed by bending
3. F2T2 screw constructs failed by a toggling mechanism in a “windshield wiper” fashion as the capitulum was loaded, due to not having a head
4. No difference between constructs in mean stiffness, yield load and load at failure

Question 5

Moores, VCOT, 2014:
Shaft screw for humeral condylar stabilization

1. Did IOHC cases have a greater complication rate than humeral condylar fracture cases?
2. Median time to fracture union?

Answer 5

Moores, VCOT, 2014:

1. No difference in complication rates
2. 7 weeks to fracture union

Question 6

Barnes, Vet Surg, 2014:
Safe corridor for transcondylar screw insertion

1. Guidelines for lateral entry/exit points?
2. Guidelines for medial entry/exit points?
3. Radiographic vs CT measurement of humeral condylar diameter?
4. Is intra-articular penetration of the screw more likely when drilling from medial to lateral or lateral to medial?

Answer 6

Barnes, Vet Surg, 2014:

1. Lateral entry/exit points: 0.3 x humeral condylar diameter cranial and distal to the lateral epicondyle
2. Medial entry/exit points: 0.3 x humeral condylar diameter cranial and 0.2 x humeral condylar diameter distal to the medial epicondyle
3. Strong agreement between radiographic and CT measurements of humeral condylar diameter
4. Intra-articular penetration of the screw is more likely when drilling from medial to lateral

Question 7

Perry, Vet Surg, 2015:
Humeral condylar fractures

1. What % had a visible fracture gap on immediate post-op radiographs?
2. Complication rate?
3. Outcomes at a median of 7 weeks post-op?
4. Was IOHC associated with a higher complication rate or poorer outcomes?

Answer 7

Perry, Vet Surg, 2015:

1. 42% had a visible fracture gap on immediate post-op radiographs
2. 42% complication rate
3. At a median of 7 weeks post-op, 50% had excellent outcomes, 21% had good outcomes, 23% had fair outcomes and 5% had poor outcomes
4. IOHC was not associated with a higher complication rate or poorer outcomes

Question 8

Gonsalves, VCOT, 2016:
3.0mm headless compression screw vs 3.5mm cortical screw for humeral condylar fractures

1. Stiffness of the headless compression screw vs cortical screw?
2. AMI of the headless compression screw vs cortical screw?
3. Regardless of screw selection, supplementation with an anti-rotational device is recommended - true or false?

Answer 8

Gonsalves, VCOT, 2016:

1. Cortical screw constructs had a 36% higher stiffness compared to headless compression screw constructs
2. AMI of the cortical screw was 2.7 times larger than that of the headless compression screw
3. True

Question 9

Vaughn, VCOT, 2016:

1. Were bicortical screws or monocortical screws stronger in pullout?
2. What was the correlation between screw working length and pullout forces?

Answer 9

Vaughn, VCOT, 2016:

1. Bicortical screws were stronger in pullout than monocortical screws, except in the lateral epicondylar crest where there was no difference
2. Strong linear correlation between screw working length and pullout forces - screw working lengths should be maximised when strength of fixation is a concern, and even if a bicortical screw cannot be placed, maximizing the length of the monocortical screw may improve fixation strength

Question 10

Cinti, VCOT, 2017:
Lateral humeral condylar fractures

1. Differences between number, diameter and direction (convergent or parallel) of K wires/Steinmann pins with regard to time to bone healing or incidence of complications?
2. % of implant migration in K wires that were bent vs not bent before cutting?
3. What % had a persistent radiolucent fracture line at 4 weeks post-op?

Answer 10

Cinti, VCOT, 2017:

1. No differences in time to bone healing or incidence of complications between number, diameter and direction of K wires/Steinmann pins
2. Implant migration occurred in 5% of K wires that were bent vs 31% of K wires that were not bent
3. 11% had a persistent radiolucent fracture line at 4 weeks post-op

Question 11

Coggeshall, Vet Surg, 2017:
Adjunct fixation with a K wire or plate for lateral unicondylar humeral fractures

Which was biomechanically superior - adjunct plate fixation or adjunct K wire placement?

Answer 11

Coggeshall, Vet Surg, 2017:

Adjunct plate fixation was biomechanically superior to adjunct K wire placement as plate constructs reached higher stiffness, yield load and failure load

Question 12

Chase, Vet Surg, 2019:
Transcondylar screw for IOHC

1. Post-op complication rate?
2. What % of the post-op complications were SSI?
3. How much more likely were dogs with a SSI to have unsatisfactory long-term outcomes than dogs without a SSI?

Answer 12

Chase, Vet Surg, 2019:

1. 69% post-op complication rate
2. 61% of the post-op complications were SSI
3. Dogs with SSI were 28 times more likely to have unsatisfactory long-term outcomes than dogs without SSI - 100% of dogs with SSI had an unsatisfactory long-term outcome vs 52% of dogs without SSI

Question 13

Moffatt, VCOT, 2019:
Repair of T-Y humeral condylar fractures with LCPs

1. What % had a post-op articular step defect of <1mm?
2. Short-term outcomes?
3. Complication rate?

Answer 13

Moffatt, VCOT, 2019:

1. 94% had a post-op articular step defect of <1mm
2. Full functional outcome in 69% and acceptable functional outcome in 31% in the short-term
3. 15% complication rate