Chapter 77 - Principles of fracture treatment Flashcards
1
Q
What are examples of severe fractures causing non-weight-bearing lameness?
A
Multiffragment failures of the third metacarpal/metatarsal bone (MCIII/MTIII).
2
Q
What fractures may be managed with a bandage alone?
A
Fractures of MCII/IV or MTII/IV.
3
Q
Why might radiography initially fail to detect fractures in horses?
A
Fractures may not be visible until 7–10 days after trauma.
4
Q
When is scintigraphy used in fracture diagnosis?
A
2–3 days after trauma to locate bony lesions.
5
Q
What fractures should always be treated surgically?
A
Fissure fractures penetrating a joint.
6
Q
What materials are preferred for casts?
A
Fiberglass.
7
Q
Why are fiberglass casts advantageous?
A
Lightweight and breathable, improving animal comfort.
8
Q
What is the first sign of complications under a cast?
A
Hot areas, edema, or foul odors.
9
Q
Why should the first cast change occur after 3–4 days?
A
To address subsiding swelling and prevent looseness.
10
Q
What interval is recommended for cast changes in foals?
A
Every 10–14 days.
11
Q
What can prolonged external coaptation lead to in joints?
A
Cartilage degeneration and joint disease.
12
Q
How does skin trauma from casts affect fracture healing?
A
It can lead to infection and compromise healing.
13
Q
What is the risk of “compartment syndrome” under a cast?
A
Tissue necrosis due to swelling and pressure.
14
Q
How can cast maintenance extend its usefulness?
A
Hosing with water daily.
15
Q
What causes foot pain after cast removal?
A
Expansion of the hoof after being constricted.
16
Q
What type of fractures are suitable for nonsurgical management?
A
Deltoid tubercle, nonarticular patellar fractures, and fissure fractures of radius/tibia.
17
Q
What causes loss of proteoglycans in articular cartilage?
A
Immobility during prolonged casting.
17
Q
Name the type of fractures amenable for stall rest
A
deltoid tubercle,
nonarticular patellar fractures,
fissure fractures of the radius and tibia,
fractures of the scapular spine
17
Q
Fissure fractures penetrating a joint should always…
A
Fissure fractures penetrating a joint should always be treated surgically.
17
Q
A
Figure 77-2. Craniocaudal (left) and lateromedial (right) radiographic views of a fissure fracture in the proximal metaphysis of the tibia of an adult horse.
18
Q
A
Figure 77-1. An adult horse suffering from a fissure fracture of the tibia, supported by a rescue net. The net, which is applied relatively snugly to allow the horse to rest in it, is tolerated very well.
18
Q
Why does equine bone healing occur more slowly compared to other species?
A
Equine bones have a slower remodeling process and less efficient healing than ruminants, small animals, and humans.
19
Q
What are two external fixation techniques used in horses?
A
Transfixation pin casts and external fixators.
20
Q
What is the main biomechanical principle behind the high bending stiffness of pins?
A
It depends on the modulus of elasticity and the area moment of inertia, which increases significantly with the pin diameter.
21
Why do multifragment fractures heal better than simple fractures with transfixation pin casting?
Micromotion is distributed across more fragments, reducing stress and strain in the fracture gaps.
21
what type of fractures is transfixation pin casting particularly effective for?
Comminuted fractures of the phalanges and distal MCIII/MTIII, and MCP joint injuries.
22
What is the recommended pin diameter range for transfixation pin casting in horses?
4 to 6.3 mm.
23
Why is pin divergence recommended during placement?
Divergence of 30 degrees strengthens fixation and lowers the risk of postoperative fracture.
24
Bending stiffness is defined by
Bending stiffness is defined by the product E (modulus of elasticity) × I (area moment of inertia)
24
Most pins and implants are made of
316L surgical steel
24
The area moment of inertia of cylindrical objects is defineda formula which is it?
The area moment of inertia of cylindrical objects is defined by
**I = π × r4/4.**
As I is calculated from the fourth power of the radius (r), **small increases in the diameter** have a **great effect on bending stiffness**
25
what is the recommended diameter of the pin?
Therefore it is recommended that pin tracts are in the range of 20% of bone diameter.
26
Each pin should diverge from the frontal plane for X to 15 degrees so that the pins diverge from each other by Y degrees, which results in a stronger fixation and lower risk for postoperative fracture
Each pin should diverge from the frontal plane for 10 to 15 degrees so that the pins diverge from each other by 30 degrees, which results in a stronger fixation and lower risk for postoperative fracture
26
27
The transifxation pins should be separated by
2 to 4 cm
28
what is the best way to reduce heat control?
An effective method of heat control is to initially drill a smaller hole, followed by stepwise enlargement through larger drill bits.
29
what is the temperature within the bone associated with bone necrosis in drilling?
55ºC = loosening
29
A pin with a diameter that is** X mm larger** than the prepared hole (radial preload of 0.1 mm) provides the best pin holding strength with the least weakening of the bone surrounding the implant.
A pin with a diameter that is **0.1 mm larger** than the prepared hole (radial preload of 0.1 mm) provides the best pin holding strength with the least weakening of the bone surrounding the implant.
30
What is the benefit of step drill bits compared to sequential drilling?
They allow quicker preparation of holes without exceeding the thermal damage threshold for bone.
31
What temperature threshold must not be exceeded to avoid thermal bone damage?
47°C for more than 1 minute.
31
What type of pins are recommended for transfixation pin casting, and why?
Positive-profile pins because they resist pullout forces and minimize loosening.
32
What can happen if pinholes exceed 10% of the bone's diameter?
Significant reduction in torsional strength and increased risk of fractures.
33
What is the purpose of using cold sterile saline during drilling?
To reduce heat and prevent thermal damage to the bone.
33
What materials are typically used for the fiberglass cast layer?
Fiberglass cast tape, applied over stockinet and padding.
33
Why should threaded pins engage both cortices?
To ensure stability and prevent loosening.
34
What additional step is taken to secure pin ends within the cast?
They are incorporated into the cast using dowels or acrylic layers.
35
What is the recommended action when a pin becomes loos
Immediate removal and possible replacement at a different location.
35
What is the most common complication of transfixation pin casting?
Pin tract infection leading to loosening.
35
What leads to ring sequestrum formation around pins?
Weight bearing and osteolysis around the pin.
36
Why should diaphyseal pins be avoided?
They have a higher risk of complications like sequestrum formation and pathologic fractures.
37
What complication can occur due to insufficient distance between skin and fixation devices?
Skin necrosis due to swelling.
38
Advantages of transfixation pin casting
minimal load on the fracture site
and minimal distraction
and movement between the fragments
39
what is the ideal cast padding layer in mm?
5 to 7mm layer of fiberglass cast
39
disadvantages of external coaptation
development of cast disease, osteoporosis,
contracted hooves,
tendon laxity, apply to this type of treatment
40
how much time can the transfixation be maintained before simple casting?
6 to 8 weeks
40
Pin tract infection with ring sequestrum formation can occur and is preceded by a sudden onset of lameness occurs typically in which type of horses?
heavy horse (>500kgs) after 2 weeks place a new pin after removal in a new place
40
Name types of external fixation
The Steinmann pins and Schanz screws pins with a threaded end)
41
Why has the use of external skeletal fixators in horses been largely abandoned?
Due to complex application and high complication rates.
42
What is a major determinant of axial stability in transfixation pin casting?
The fiberglass cast material.
42
What indicates pin tract infection?
Sudden onset of lameness.
42
How is drainage from a pin tract managed?
Curetting and flushing the tract.
43
What precautions are taken during a cast change involving pin removal?
Temporary filling of the tract with antiseptic-soaked sponges.
43
Why is early recognition of pin loosening critical?
To prevent severe complications such as pathologic fractures and sepsis.
43
What risk does osteoporosis pose during fixation?
It weakens the bone, increasing the likelihood of pathologic fractures.
43
What is "cast disease"?
Complications like osteoporosis, contracted hooves, and tendon laxity caused by prolonged casting.
43
What design feature of pins can prevent stress concentration?
A tapered thread-run-out (TRO) feature.
44
If several pins are loose what should you do?
Depending on the degree of fracture healing, it is important that pins be removed one at a time
44
What is ORIF in internal fixation?
Open Reduction and Internal Fixation, involving wide skin opening and tissue separation to stabilize fractures.
44
44
Why is minimally invasive plating preferred in some cases?
It preserves the hematoma and growth factors around the fracture, improving healing outcomes.
44
Why are multifragment radius fractures with caudal defects not suitable for surgery?
They have poor healing potential due to stress cycling leading to implant failure.
45
What is the purpose of a drill guide in fracture treatment?
Stabilizes the drill bit, reduces tissue trauma, and prevents bit slippage.
46
Why are sharp drill bits important in equine fracture treatment?
To minimize heat generation and improve precision during drilling.
47
How does the plate-bending press help in equine fracture treatment?
Allows precise contouring of plates to match bone curvature without damage.
48
What is the primary function of cortex screws?
Provide strong fixation in dense cortical bone.
49
Why are cancellous screws rarely used in equine fixation?
They are designed for soft bone and are less effective in equine cortical bone.
50
What is unique about cannulated screws?
They have a central canal for guide wires, improving accuracy.
51
What advantage do self-tapping screws offer?
Eliminate the need for pre-tapping, reducing time and effort.
51
Why are locking head screws beneficial in internal fixation?
Provide stable angular fixation and resist higher forces.
52
Why are unicortical screws rarely used in horses?
Bicortical fixation offers greater strength, which is critical in equine applications.
53
What are Acutrack screws, and when are they used?
Tapered, self-compressing screws used for specific equine fracture repairs.
54
How are locking compression plates (LCP) applied differently from DCPs?
LCPs are placed over the periosteum, reducing disruption to blood supply.
54
What is Halsted’s principle in surgical technique?
Gentle handling of tissues to minimize trauma and promote healing.
55
What are the mechanical advantages of locking screws?
They resist bending and shear forces better than traditional screws.
55
Why is the direction of screw insertion critical in LCPs?
Screws must align perpendicularly to ensure proper locking and stability.
56
What was the primary innovation of the AO’s locking head screws?
Self-centering, angular stability, and unicortical application capabilities
57
What is the significance of screw pitch in fixation?
Determines the holding power and insertion characteristics of the screw.
57
Why is the Herbert screw not commonly used in general equine fractures?
It’s specialized for small fractures like condylar breaks in MCIII/MTIII.
58
How does screw insertion torque vary among screw types?
Cannulated screws require higher torque than cancellous or cortex screws.
59
Cortex secrews 4.5 mm have a __mm thread width
0.7mm
59
Figure 77-8. Proper technique of plate contouring with the bending press. (A) Plate contouring should be performed with the lever in approximately the horizontal position. This allows the best control over the amount of bending achieved. (B) The resting plate for the plate to be bent (a) and the anvil (b) have complementary contours, allowing plate bending without damaging the plate. The resting plate can be moved up and down (arrow) with the turning nut (c) at the bottom of the bending press. (C) For a convex bend, the plate is positioned toward the center of the bending press matching the contours of the resting plate and anvil. (D) For a concave bend, the plate is positioned toward the front of the bending press, again matching the contours of the resting plate and anvil. (E) Trying to achieve a gentle bend in the plate with the lever in this position is not possible; an acute excessive bend will be the result. The turning nut should be turned to lower the resting plate until the lever is in a horizontal position.
60
Figure 77-10. Schematic drawing of a 7.3-mm cannulated screw with the guide pin inserted and half of the shaft removed. Insert: the reverse-cutting design of threads, which facilitates screw removal after healing of the fracture.
60
the LHS has more or less threads than the cortex screw?
The locking head screw has more threads than the standard cortex screw because its pitch is smaller
61
62
LHS can be inserted by hand?
yes but it takes long time because it has many threads so USE a POWER DRIVE and place 90 degrees relative to long axis
62
The size of a screw is determined by the outside __________ of the threads. The
The size of a screw is determined by the outside diameter of the threads.
63
Is the head of 4.5 mm cortex screw the same as 5.5 mm cortex screw?
because the screw head has the same size as the 4.5-mm cortex screw, the distance between the outside of the threads and the outside of the screw head is smaller (only 1.25 mm on either side).
64
Wich part of the combi-hole are the LHS introduced?
in the thread hole within the combi-hole, and cortex screws in dynamic compression unit (DCU ouside)
64
what are the strongest screws avaialble?
The 5.0-mm locking head screws are the strongest screws available for equine fracture treatment because of their large core diameter (4.3 mm; see Figure 77-11).
65
The 4.0-mm locking head screw can be used with the _____mm LCPs. They have the same head design as the 5.0-mm locking head screw but a thinner screw design. These screws are rarely used in equine osteosynthesis.
The 4.0-mm locking head screw can be used with the 4.5/5.0-mm LCPs. They have the same head design as the 5.0-mm locking head screw but a thinner screw design. These screws are rarely used in equine osteosynthesis.
66
Name the 3 screw functions
lag screws
position screws
plate screws
67
A cortex screw placed in position means it has glide hole or not?
cortex screw placed as a position screw (i.e., with no lag effect): its threads engage bone on both sides of a fracture, and because no glide hole was prepared in the near-cortex, no interfragmentary compression is achieved.
68
lag fashion what will the cortex screw provide?
lag technique is used to insert cortex screws so that they act in lag fashion, providing interfragmentary compression
69
In the lag technique describe the making of glide hole and thread hole
The cis-cortex or near-cortex is drilled with a drill bit having the same diameter as the outside thread diameter of the screw (Figure 77-13, A). This is referred to as overdrilling. Therefore, at insertion of the screw, the threads do not engage bone in that cortex but glide through; hence this portion of the hole is called the glide hole. The outside diameter of the insert drill sleeve is the same as that of the glide hole, and the inside diameter is the same as that of the smaller drill bit, which has, for practical purposes (see Table 77-1), an identical diameter as the core of the screw. Insertion of this drill sleeve into the glide hole ensures concentric drilling of the trans-cortex and subsequent accurate reduction of the fracture (see Figure 77-13, B). The hole drilled through this sleeve across the trans-cortex or far cortex is referred to as the thread hole.
70
In the end of the lag technique countersink is performed, what is it?
To allow a greater contact area between the screw head and the bone, a depression is created at the near-cortex using the countersink (see Figure 77-13, C). This decreases stress concentration at the screw head-bone interface
71
what is the 2 last steps?
The depth gauge is subsequently used to determine the total length of the screw, including the head (see Figure 77-13, D). Therefore, the length of the screw is measured to include the head. The depth gauge has a small hook at the end of its thin shaft that is inserted through the thread hole. By slightly tilting the instrument to one side, the hook catches the opposite cortex, and by sliding the movable portion toward the countersink depression, the exact length of the screw is determined.
The tap is inserted through the drill sleeve (here called the tap sleeve) into the glide hole and the threads are cut into the thread hole (see Figure 77-13, E). Flush and insert the screw
72
In equine because adequate bone stock is usually present to ensure fixation of the scrw in the prepared hole the size of the screw either is the same as the measured with depth gauge or
or is 1 to 2 mm shorter.
73
Figure 77-13. Lag technique, shown on a lateral condylar fracture of the distal MTIII. (A) The cis-cortex is overdrilled. (B) The insert drill bit is placed into the glide hole and advanced past the fracture plane, and the concentric thread hole is drilled across the trans-cortex. (C) A depression for the screw head is prepared with the countersink. (D) The required length of the screw is determined with the depth gauge. (E) The threads are cut into the thread hole with the tap. (F) The screw of predetermined length is inserted and solidly tightened with the hexagonal-tipped screwdriver.
74
lag screw technique is used in which type of screws?
cannulated or partially threaded cancellous screws
75
describe the principle of lag screw technique
a lag screw (a partially threaded cancellous screw or occasionally a cannulated screw) is inserted after using a drill bit of only one size (screw shaft diameter) across the entire bone. Threads are cut along the total length of the hole with the cancellous tap, and the lag screw is inserted. The threads in the near (cis)-cortex should not be engaged
by the screw threads but only those of the trans-cortex, allowing achievement of interfragmentary compression.1–4 Because the hardness of equine bone makes screw insertion difficult, it may be advisable to enlarge the cis-cortex with a 4.5-mm-diameter drill bit after first drilling the entire hole with the 3.6-mm
drill bit.
76
In the placement of cannulated screws it is advisable to select screws Xmm shorter than the length of the guide wire
It is advisable to select a screw 3 to 5 mm shorter than the length of the guide wire inserted within the bone, to ensure secure seating of the wire throughout the implantation procedure.
77
placement of a guide wire in the desired location. A special drill sleeve allows insertion of parallel screws close together. It is advisable to predrill equine cortical bone with a small drill bit before inserting the guide wire to prevent bending it. All instruments are cannulated to accept the guide wire. The size of the drill bit depends on the size of the screw to be implanted and the size of the guide wire. Once the guide wire is in place, its correct position and depth is ensured through radiography. If necessary, adjustments are made at this time. The measuring device is then placed over the portion protruding out of the bone. The length of guide wire located in the bone is determined, and this determines the length of screw required the cannulated drill bit is placed over the guide wire and the hole of predetermined length is prepared. The hole is tapped and finally the selected screw is inserted and firmly tightened (Figure 77-14). At the end, the guide wire is removed.
78
which type of screw is not advisable to insert if removal is thought to be done?
Cortex and locking head screws are easily removed because of their fully threaded design. However, after a fracture has healed, a cancellous screw may be impossible to remove from hard equine bone, because during fracture healing, the precut threads in the near-cortex fill in with solid bone.
79
which screw has hexagonal head? which screw has star head?
hexagonal head - cortex screw
star head - LHS
80
what is the name of the device devoleped to remove in case of the head of the screw is stripped?
A special screw-retrieval instrument, the so-called conical extraction screw, has been designed for such situations (Figure 77-15).
81
82
when a screw head is broken off and the shaft of the screw is visible what do you do?
you remove the bone around the screw with a bone gauge to a depth of 5 mm - insert hollow reamer or extraction bolt if it doesn't come out wih pliers
83
once the broken screw head with exposed shaft by the bone gauge what do you do?
The exposed screw shaft can be grasped with long-nosed pliers designed for screw removal and extracted by counterclockwise rotation of the pliers.
84
if the shaft of the broken head screw is not visible what do you do?
If the shaft of the broken screw is not visible, a special hollow reamer is used in a counterclockwise motion to remove bone surrounding the screw hole to a level of 5 mm below the top of the broken screw. Then the hollow reamer is removed and a designated extraction bolt is inserted with a counterclockwise rotational movement over the broken screw shaft. The threads of the extraction bolt will engage in the shaft of the broken screw and once adequate connection between the device and broken screw is established continued counterclockwise rotation removes the broken screw. A special screw-retrieval set containing the instruments described above has been developed for every screw size.
85
What tool is used if the screw shaft is not visible?
A hollow reamer.
86
What is the main advantage of LC-DCP over DCP?
Reduced contact with the bone, minimizing local bone resorption.
87
What feature differentiates narrow and broad DCP plates?
Narrow plates have straight holes; broad plates have offset holes.
88
What problem does the LC-DCP address compared to conventional plates?
Improved resistance to cyclic loading and stress distribution.
88
What happens when a screw is inserted in the loading position of a DCP?
It moves down the inclined hole, compressing the fractured bone ends
89
What angulation range do LC-DCP holes allow for screw insertion?
Up to 40 degrees.
89
How much compression can be achieved using two screws in load positions?
Up to 4 mm.
90
Why might DCP plates soon be eliminated?
They are being replaced by more advanced plates like the LCP.
91
Why is the LC-DCP drill guide unique?
It has undercuts matching those on the plate
91
What mechanical advantage does the LC-DCP offer over DCP?
Increased resistance to cycling failure.
92
What device measures depth during DCS implantation?
A measuring device placed over the guide pin.
92
Why is correct guide pin placement crucial for DCS plates?
To ensure proper alignment of the plate with the bone.
92
What is the barrel angle of a DCS plate?
95 degrees.
93
What is the primary application of DCS plates in equine surgery?
Treating long bone fractures.
94
What is a unique feature of the DCS lag screw shaft?
It has a flattened design to prevent rotation within the barrel.
95
96
97
98
99
Figure 77-24. Preoperative (A) and postoperative (B & C) radiographs of a metaphyseal fracture of MTIII in an adult Icelandic pony. The fracture was repaired with a laterally applied DCS plate and a shorter dorsal DCP.
100
101
What two treatment methods are combined in the LCP?
Compression plating and internal fixation.
102
What is the defining feature of the LCP's combi-hole?
It allows the use of both standard screws and locking head screws.
103
Why is the locking head screw inserted orthogonally?
To ensure proper locking within the combi-hole.
104
What type of screws provide greater strength in LCPs?
Locking head screws with a thick core and thin threads.
105
How do bevel modifications improve LCP design for equine use?
They allow insertion through smaller incisions.
105
What is the maximum compression achievable using a single plate?
4 mm with two loaded screws on either side of the fracture.
105
What allows LCPs to achieve precise interfragmentary compression?
Alternate tightening of cortex screws on either side of the fracture.
106
What is the role of pointed reduction forceps during plate application?
To maintain fracture reduction.
107
Figure 77-27. Repair of a simple oblique fracture of MCIII with two cortex screws applied in lag technique combined with a broad 12-hole LCP as a neutralization plate. (A) The large pointed reduction forceps maintains alignment of the fractured bone during implantation of the two 3.5-mm cortex screws. (B) The two screws are implanted and the reduction forceps is removed. (C) A 12-hole broad LCP is applied to the dorsolateral aspect of the bone. Note: in this plate only cortex screw are used. The plate was overbent at the fracture site, allowing introduction of an aluminum template between the bone and the plate. (D) A thread hole is drilled across the bone through the second most distal plate hole with the help of the universal drill guide in load position (no vertical pressure is applied to the drill bit and it is positioned at distal end of the DCU portion of the combi-hole).
Continued
107
What is the purpose of drilling screw holes in the neutral position?
To stabilize the plate without additional compression.
108
(E) The screw is inserted but not completely tightened, followed by preparation of a drill hole in neutral position (pressure is applied to the drill guide, which positions it in the neutral position of the DCU portion of the combi-hole). Note the central part of the drill guide is protruding over the drill guide at the opposite end of the plate. The second screw is inserted and both are alternately tightened, placing the fracture under axial compression. (F) An additional drill hole is prepared in neutral position in the distal fragment, followed by screw insertion and tightening. (G) A cortex screw is implanted in lag fashion across the fracture plane. (H) The remaining screw holes are prepared in neutral position, all the screws are inserted and tightened.
109
110
111
Figure 77-32. Application of two LCPs to an oblique midshaft MCIII fracture. (A) The fracture is reduced and stabilized by the two 3.5-mm cortex screws applied in lag fashion. A 10-hole broad veterinary LCP is applied to the bone with the plate holder and temporarily fixed in place with the push-pull device. By turning the piston clockwise (arrow), the plate is pressed onto the bone surface. (B) To facilitate good plate-bone contact along the entire plate, cortex screws are implanted and tightened using the plate screw technique at both ends and in the center near the fracture. Once in place, the lateral 11-hole narrow veterinary LCP is applied to the bone using the same technique. Note that the plate can be applied farther distad on the lateral aspect of the bone than on the dorsal aspect. (C) Next the holes where locking screws are to be inserted are selected and the drill guides twisted into the threaded portion of the combi-hole. Because the plate is solidly fixed to the bone, all four drill guides provided in the set are applied, followed by drilling all four holes. (D) The locking head screws are inserted and tightened. The four drill sleeves for the locking head screws are then placed into selected plate holes of the lateral plate, making sure that screws can be placed perpendicularly without interfering with previously inserted implants. (E) All the remaining plate holes are filled with cortex screws inserted using the plate screw technique. Where indicated, lag technique is applied to increase interfragmentary compression.
112
113
113
Figure 77-34. Preoperative (A) and postoperative (B) radiographs of an oblique, spiral radial fracture. The fracture was repaired with a 17-hole 5.5/5.0-mm veterinary LCP cranially and an 18-hole 4.5/5.0-mm human femoral LCP (a slightly axially bent plate) laterally.
114
115
116
117
Figure 77-43. This long oblique humeral fracture (A) was treated with an intramedullary interlocking nail. To provide a greater screw-bone contact area, washers were used. The craniocaudal (B) and lateromedial (C) 2-month follow-up radiographs show progressive bone healing in the fracture gap. Bone length is maintained.
117
How is the plate fixed initially during axial compression?
screws are inserted in a neutral position in one end of the fracture.
117
What is the purpose of the tension device in axial interfragmentary compression?
To pull the plate toward the device, applying compression to the fracture site.
118
What is the unique feature of LCP compared to other plates?
It functions as a locked internal fixator, eliminating the need for exact contouring.
119
What material is used in plate luting?
Methyl methacrylate bone cement.
119
Why must bone cement be kept out of fracture lines?
It retards or prevents bony union
120
What angle should locking screws ideally not exceed when inserted into bent plates?
More than 5 degrees.
121
What complication arises when inserting screws through a fracture line?
Instability unless the lag technique is applied.
121
What type of angulation is allowed for 4.5-mm screws in a 4.5/5.0-mm LCP?
40 degrees longitudinal and 7 degrees lateral.
121
What is the minimum screw requirement for long bone fractures in horses?
ore than four bicortical screws on each side of the fracture.
122
How does the LCP design prevent osteoporosis under the plate?
By leaving a 2-mm gap between the plate and bone.
122
What is the recommended positioning for a second plate?
At 90 degrees to the first plate's long axis.
123
How does a tension band plate work?
It transforms tensile forces into compressive forces.
124
What is the primary example of a tension band plate application?
Fixation of an olecranon fracture.
125
What should be placed in cortical bone defects to enhance stability?
A cancellous bone graft or bone-replacement material.
126
Why must every hole in a plate be filled with a screw?
To maximize stability and stiffness.
127
What is the preferred screw insertion angle in plate fixation?
Perpendicular to the bone surface.
128
How does the plate function change with a simple versus comminuted fracture?
Compression for simple fractures; neutralization for comminuted fractures.
129
What is the risk of using locking head screws without cortex screws first?
The plate cannot be pressed down onto the bone.
130
What should be done if bending LCPs is necessary?
Bend them between combi-holes over a longer segment.
131
Why is the human femoral LCP ideal for equine radius fractures?
Its slight bend matches the craniocaudal curvature of the equine radius.
132
What is the primary advantage of the human distal femoral plate in equine fracture repair?
It allows multiple locking head screws to be inserted at diverging angles, enhancing strength.
133
What is the purpose of the variable-angle LCP (VA-LCP)?
To allow screws to be angled within a 30-degree cone around the central axis of the plate hole.
134
Why are VA-LCP holes shaped like cloverleaves?
To facilitate locking screws at variable angles.
134
What material is used to manufacture LCPs?
Stainless steel.
135
What are bending screws used for in the Compact 2.4 UniLOCK system?
To assist in bending the plate during surgery.
136
What are the key features of the new 4.5-mm LCP T-plate?
It is thicker, accommodates cortex or locking screws, and is suited for areas with tension.
137
What is minimally invasive plate osteosynthesis (MIPO)?
A technique emphasizing minimal disruption of soft tissue and periosteal envelope during fixation.
138
Why is MIPO limited in adult horses?
Their size and weight make stability challenging with minimal fixation.
139
What is the main disadvantage of locking head screws in LCP applications?
They require insertion perpendicular to the plate axis.
140
What is a "stacked pin" method?
A technique involving multiple parallel pins to fill the medullary space for stability.
141
How does reaming impact intramedullary nail application in horses?
It destroys intramedullary blood supply, slowing healing.
142
What is the difference between cerclage and hemicerclage wires?
Cerclage wires encircle the bone fully, while hemicerclage wires pass through drilled holes.
143
What advantage does UHMWPE cable have over stainless steel cerclage wire?
Higher tensile strength and fatigue resistance.
144
Why are Rush pins unsuitable for comminuted fractures?
They cannot provide stability in fragmented bone structures.
145
What are the clinical applications of stainless steel cables in equine surgery?
Stabilizing atlantoaxial fractures and tension banding in sesamoid injuries.
146
What is the purpose of a tension band wire in mandibular fractures?
To stabilize fractures using a figure-of-eight configuration.
147
How does the funnel-shaped guide facilitate VA-LCP drilling?
It supports angled drilling up to 30 degrees.
148
What is the purpose of combi-holes in LCP designs?
They accommodate both cortex and locking screws.
149
What type of external coaptation may be used immediately after surgery?
A fiberglass cast or a heavy splint bandage.
150
Why is a plastic adhesive sheet used during pool recovery?
To protect the limb and skin incision.
151
What is the purpose of splitting a fiberglass cast in half?
To allow evaluation and wound management of the limb.
152
What complication might arise from excessive support in young foals?
Temporary weakness of the flexor tendons.
153
Why is it important to maintain some level of pain in postoperative management?
To ensure the patient protects the injured
154
What is the major complication after fracture repair aside from infection?
Laminitis.
155
Under what circumstances are cortex screws typically removed in horses?
If they cause pain or bone reactions, or upon the owner's request.
156
Why is the removal of cerclage wire usually unnecessary?
It does not typically cause complications unless it breaks.
157
When are screws typically removed in condylar fractures of MCIII/MTIII?
About two months postoperatively.
158
In which cases are plates generally removed in horses?
In foals or if the horse resumes an athletic career.
159
Why might implant removal be staggered when two plates are used?
To reduce the risk of refracturing through screw holes.
