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What method of spinal fixation requires the largest force to disrupt the bone-implant interface?
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A 35-year-old patient is involved in a motor vehicle accident and sustains multiple fractures including a closed comminuted proximal meta-diaphyseal tibia fracture. The surgeon is considering bridge plating the fracture using a minimally invasive approach. Which of the following is true regarding bridge plating?
A locked plate construct (locked screws) or hybrid construct (locked and non-locked screws) is necessary.
Periosteal stripping is performed through two incisions proximal and distal to the fracture.
Bridge plating is performed following direct reduction of the fracture.
AO Type A diaphyseal fractures are best treated with this technique.
Bridge plating with a long working length creates a flexible, axially stable construct.
After application of a unilateral tibial external fixator, it is observed that the frame does not provide sufficient rigidity across the fracture site. Altering the external fixator in which of the following ways will have the greatest impact on frame stiffness?
Increasing the distance between pins in each fragment
Increasing the pin diameter
Reducing the distance between bone and connecting bar
Increasing the connecting bar diameter
Adding one stacked connecting bar
Which of the following techniques increases strength and stability to an external fixation construct?
Unicortical pin fixation
Decreasing total pin separation distance
Increased working distance from the pin to fracture site
Decreasing the distance between the bone and the construct
Using smaller diameter pins
A 27-year-old male undergoes intramedullary nailing of a midshaft tibia fracture with static locking proximally and distally. There is minimal healing noted 3 months postoperatively and the decision is made to dynamize the nail. For intramedullary nail dynamization, an interlocking screw should be placed in which of the holes shown in Figure A?
A and C
C and B
A locked plate used in a bridge plate fashion is biomechanically most similar to which of the following fixation methods?
Lag screw plus non-locked neutralization plate
External fixator without compression
Lag screw plus locked neutralization plate
External fixator used in compression mode
Which of the following defines the working distance of a plate in a plate/screw fracture fixation construct?
The length of the interfragmentary lag screw
The length between the 2 screws closest to the fracture on each end of the fracture
The distance from the bone to the plate
The length from the screw closest to the fracture to the screw furthest from the fracture on the same end of the plate
The length between the 2 screws furthest from the fracture on each end of the plate
A 24-year-old female presents with a transverse midshaft humerus fracture. Which of the following implants would create the most compression on both the far and near cortices?
Compression plate with concave bend (ends bowed towards bone)
Large fragment locking plate with 3 bicortical locking screws proximal and distal to the fracture
Compression plate with convex bend (ends bowed away from the bone)
Sarmiento style fracture brace
Which of the following is true regarding rigid locking plate constructs in fracture fixation?
Locking plates always enhance fracture healing more than non-locking plating
Locking plates reduce interfragmentary strain more than non-locking plating
Locking plates are best utilized in diaphyseal fractures
Locking plates are contraindicated in patients with osteoporosis
Fractures treated with anatomic reduction and locked plate fixation demonstrate more strain than fractures treated with intramedullary fixation
A surgeon chooses a periarticular locking plate with unicortical proximal locking screws for an extra-articular distal femur fracture as seen in Figure A. Compared to an identical construct with bicortical unlocked proximal screw fixation, the periarticular locking plate with unicortical locking screws has which biomechanical properties?
Greater torsional and axial fixation strength
Less torsional but greater axial fixation strength
Equal torsional and axial fixation strength
Greater torsional but less axial fixation strength
Less torsional and axial fixation strength
Which of the following scenarios of treatment of a humerus fracture best achieves low strain at the fracture site and high stiffness of the treatment construct?
Functional bracing of a transverse midshaft fracture
Comminuted midshaft fracture with locked bridge plating
Short oblique fracture with interfragmentary lag screw and locked neutralization plate
Uniplane external fixation of a spiral open fracture
Oblique fracture with intramedullary nail fixation
The greatest biomechanical difference between unicortical and bicortical locking screws is seen when what force is applied?
Bending on the side of the plate
Bending on the surface perpendicular to the plate
Which of the following fracture patterns (Figures A through E) has the least amount of evidence-based support for use of locking or hybrid plating techniques?
Which of the following Figures shows a fixation construct achieving absolute stability?
A 25-year-old male sustained the fracture seen in Figure A and undergoes open reduction internal fixation of the injury. What type of plating technique is used for the ulna?
Figure A is a radiograph taken after an open reduction and internal fixation of a periprosthetic distal femur fracture. With this type of hybrid locked plate fixation, what is the difference between screw A and screw B?
Screw A can assist in fracture reduction while screw B provides a fixed angle support
Screw A provides improved axial stiffness while screw B provides a fixed angle support
Screw A can be used to reduce the plate to bone while screw B can be used to lag fracture fragments together
Screw A provides a fixed angle support while screw B can be used to reduce the plate to the bone
Screw A can be used to lag fracture fragments together and screw B increases the plate bone frictional stability
An adolescent patient is treated with a 6mm solid intramedullary nail. Compared to a 12mm solid nail of the same material, the 6mm nail has:
1/2 the torsional rigidity
1/4 the torsional rigidity
1/16 the torsional rigidity
1/8 the torsional rigidity
the same torsional rigidity
The resistance to pullout of a screw in osteoporotic bone is increased by all of the following EXCEPT?
Placement parallel to the trabecular pattern
Purchase in cortical bone
Use of a fixed angle (locking screw construct)
Tapping prior to screw placement
Augmentation with polymethylmethacrylate
Locking plate technology has relative indications for use in all of the following, EXCEPT:
As a bridge for severely comminuted fractures
Osteoporotic metaphyseal fractures
Short fracture segments
Oligotrophic diaphyseal nonunions
Indirect fracture reduction techniques
How does a dynamic compression plate achieve compression at the fracture of a long bone?
Eccentric placement of a cortical screw into a hole in the plate
Placing a cortical screw in lag fashion by overdrilling the near cortex
Locking of the head of the screw into a threaded hole in the plate
Concentric placement of a cortical screw into the center of the hole in the plate
The plate allows secondary healing of bone and does not acheive compression at the fracture site
Assuming all other variables are the same, which of the following increases fixation construct stiffness in a locking plate model?
Unicortical locking screws compared to bicortical locking screws
Angular cross-threading screws into a plate
Overdrilling the near cortex for the screw holes
Far cortical locking screws
Increased number of screws in the plate
A long oblique diaphyseal fracture is internally fixed with 2 lag screws. There is 2 mm of residual fracture fragment gap following screw fixation. This construct has which of the following compared to a comminuted diaphyseal fracture internally fixed with a long bridge plating technique?
Greater interfragmental strain
Greater primary Haversian remodeling
Greater union rate
Greater callus volume formation
The distance of bone traversed by a screw is defined as which of the following terms?
Area moment of inertia
Limited contact dynamic compression (LCDC) plates have what advantage over standard dynamic compression plates?
Less implant-bone and fracture gap micromotion
More fracture site compression
Less implant-bone contact induced osteopenia
Stiffer fracture fixation construct
More stress shielding
All of the following are indications for locked plating technology EXCEPT:
Periarticular fracture with metaphyseal comminution
Fracture in osteoporotic bone
Bridge plating for severely comminuted fractures
Compression plating of transverse fracture
Plating of fractures where anatomical constraints prevent plating on the tension side of the bone
Which statement is true regarding standard open plating techniques compared to minimally invasive submuscular plating techniques?
standard plating results in greater compromise to both medullary and periosteal bloodflow
standard plating results in greater compromise to periosteal bloodflow only
standard plating results in greater compromise to medullary bloodflow only
standard plating results in less compromise to both medullary and periosteal bloodflow
there is no difference between the two techniques with respect to periosteal and medullary bloodflow
A patient sustains the fracture shown in Figures A and B. Compared with open reduction and internal fixation with a conventional, non-locking condylar buttress plate, what potential complication is more likely to occur if this fracture is treated with closed reduction and minimally-invasive, locking screw-only fixation with a distal femur locking plate?
Non-anatomic reduction of the articular surface
Soft tissue stripping
Absence of visible callus
Devascularization of fracture fragments
You are planning an intramedullary nail to treat a geriatric patient with a peritrochanteric femur fracture. Which of the following preoperative considerations is correct regarding your implant?
The radius of curvature of an intramedullary nail is generally greater than the radius of curvature of the femur
Closed section nails have less stiffness than slotted nails
The medial/lateral nail starting point relative to the greater trochanter does not affect varus/valgus position in the fracture
The bending stiffness of your nail is proportional to the second power of the radius
Intramedullary nails allow for mostly direct intramembranous bone healing
Which of the following is the most accurate definition of stress shielding?
The decrease in physiologic stress in bone due to a stiffer structure sharing load
Electrochemical potential created between two metals in physical contact and immersed in a conductive medium
Degradation from exposure to a harsh environment
Physical movement of two plates against each other leading to mechanical wear and material transfer at the surface
Bone death secondary to compromise in blood supply