Evaluation of firm fracture fixation of distal femoral locking compression plate and condylar buttress plate. Subjects and methods: Experimental, descriptive, cross-sectional and comparative study of firm fracture fixation of distal femoral locking compression plate and buttress condylar plate in treatment of femoral supracondylar fracture (type A2) and femoral intercondylar fracture (type C2).
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STUDYING FIRM FRACTURE FIXATION OF DISTAL FEMORAL
LOCKING COMPRESSION PLATE AND BUTTRESS CONDYLAR PLATE ON THE SAMPLE OF LABORATORY FRACTURE FIXATION
Hoang Ngoc Minh 1 ; Pham Dang Ninh 2 ; Nguyen Quang Trung 3
SUMMARY
Objectives: Evaluation of firm fracture fixation of distal femoral locking compression plate
and condylar buttress plate Subjects and methods: Experimental, descriptive, cross-sectional
and comparative study of firm fracture fixation of distal femoral locking compression plate and buttress condylar plate in treatment of femoral supracondylar fracture (type A2) and femoral intercondylar fracture (type C2) Results: The linkage breakdown force on the sample of laboratory fracture fixation of distal femoral locking compression plate: Compression KA-N: 4,010.37 ± 509.50 N and KC-N: 4,620.27 ± 315.85 N; bending KA-U: 704.33 ± 110.45 N and KC-U: 699.26 ± 125.60 N; torsion KA-X: 990.79 ± 166.54 N and KC-X: 1,071.00 ± 222.38 N was higher than that on the sample of laboratory fracture fixation of buttress condylar plate: Compression LA-N: 3,200.04 ± 243.62 N and LC-N: 4,139.28 ± 766.53 N; bending LA-U: 505.76 ± 62.83 N and LC-U: 476.05 ± 59.18 N; torsion LA-X: 888.84 ± 89.02 N and LC-X: 986.26 ± 116.33 N Conclusion: Load force on the sample of laboratory fracture fixation of distal femoral locking compression plate is stronger than load force on the sample of laboratory fracture fixation of buttress condylar plate
* Keywords: Distal femoral fracture; Distal femoral locking compression plate; Buttress condylar plate; Experimental bone fixation
INTRODUCTION
Distal femur fracture in adults consists
of supracondylar, intercondylar, medial
condyl, lateral condyle fractures, accounting
for about 6 - 7% of all types of femur
fractures, of which, 70% are supracondylar
and intercondylar fractures [7] Distal femur fracture is difficult to treat, leaving many sequelae due to high energy trauma that causes complex fractures, multiple combined lesions, or low-energy injuries seen in the elderly as a result of osteoporosis [6]
1 Sontay General Hospital
2 103 Military Hospital
3 Vietnam Military Medical University
Corresponding author: Hoang Ngoc Minh (drhoangngocminh@gmail.com)
Date received: 02/07/2019
Date accepted: 09/10/2019
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Indications for surgery for adult distal
femur fractures and bone combination are
agreed by the authors in the world and in
the country There are many methods and
facilities studied for fixation of distal femur
fractures such as screw plate, 950 angle
plate, DCS (Dynamic Condylar Screw)
plate, dual screw plate, condylar buttress
plate, locking plate, interlocking nail
Each of them has its own advantages and
disadvantages that have been reported in
conferences [1, 2, 4] At present, surgery
for bone combination with condylar
buttress plate and locking plate to treat
complex distal femur fractures is the first
choice as it limits the disadvantages of
other types of bone combination facilities
[3, 5] However, some reports indicate
that there is a failure rate, regardless of
condylar buttress plate or locking plate,
such as limited knee stretching, prosthetic
joint, slow bone healing or displacement
of bone To understand the cause of
failure, we should pay attention to the
postoperative firmness of these two
plates That’s why we conduct the topic
“Evaluation of firm fracture fixation of
distal femur locking compression plate
and condylar buttress plate on the sample
of laboratory fracture fixation” to grasp the
fracture fixation of plates and suggest
reasonable postoperative practice programs,
preventing complications from limited
movement and splinting, screwing off
during practice
MATERIALS AND METHODS
1 Materials
- Sets of 7-hole distal femur locking compression plates (LCP), hard bone lock screws and porous bone lock screws accompanied with sufficient quantity Intercus locking plate type, Germany pure titanium material, screws made from TiAl6V4 compound, ensuring compatibility, without auto-immune effect of the body
204 mm in length, 5.5 mm in thickness, 39.3 mm in width, 17.5 mm in width, 20.0
mm of body holes, screw types 6.5 and 5.0 mm This locking plate has good stiffness and elasticity, high biological similarity, it is designed to be suitable for distal femur anatomy The screw design is quite rigid, durable, resilient body, hard bone screws have a short pitch with a moderate depth, suitable for hard bone structure, porous bone screws have a wide and deep pitch to increase the fixing ability into porous bone, consistent with porous bone structure
- Sets of 7-hole condylar buttress plate, hard bone screws and spongy bone screws accompanied with sufficient quantity
- 72 fresh beef femurs are captured X-ray in an inclined straight posture to detect and eliminate bone diseases Bones are stored in 2-layer plastic bags at
a temperature of -200C Before the test, leave the bone at room temperature
2 Methods
* Design of research samples:
The bone combination process of distal femoral LCP and condylar buttress plate into the beef femur is done like the bone combination on clinically
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- Sample of plate - bone with fracture
line simulating a supracondylar fracture of
beef femur (type A2 fracture by AO
classification):
+ Sample KA: Locking plate system -
supracondylar fracture bone (type A2): 18
samples
+ Sample LA: Condylar buttress plate
system - supracondylar fracture bone
(type A2): 18 samples
- Sample of plate - bone with fracture
line simulating an intercondylar fracture of
beef femur (type C2 by AO classification):
+ Sample KC: Locking plate system -
intercondylar fracture bone (type C2): 18
samples
+ Sample LC: Locking plate system -
intercondylar fracture bone (type C2): 18
samples
- Force test sample:
+ Compression force test sample:
24 samples (KA-N: 6; LA-N: 6; KC-N: 6;
LC-N: 6)
+ Bending force test sample: 24
samples (KA-U: 6; LA-U: 6; KC-U: 6;
LC-U: 6)
+ Torsion test sample: 24 samples
(KA-X: 6; LA-X: 6; KC-X: 6; LC-X: 6)
Picture 1: Testing sample of distal
femoral LCP
Picture 2: Testing sample of condylar
buttress plate
* Location and testing machine:
- Location: At the Material Strengthening Laboratory, Department of Materials and Structural Mechanics, Hanoi University of Science and Technology
- Testing machine: MTS Alliance RF/300 with operating principle: The machine’s encoder will measure the compressive, horizontal bending and torsional forces acting on the test sample
as well as measure the corresponding deformation of the test sample under the impact forces Compression, horizontal bending and torsional indicators and deformation are continuously measured and transmitted to the computer The computer will automatically build up the graph of force, the deformation of the test specimen within the force limit From the graph, it is possible to calculate the strength of the sample
Test conditions: Temperature at 250C; air humidity 70% RH
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Picture 3: Measuring machine of
compression indicator of
distal femoral LCP
Picture 4: Measuring machine of
compression indicator of condylar
buttress plate
* Methods:
- Method of experimental, descriptive,
comparative research
- Research content: Study on firm
fracture fixation of the distal femoral LCP
and the condylar buttress plate - bone
- Conducting research:
+ Compressive test: Axial compression
of model of bone combination of 2 types
of fractures - bone with samples of supracondylar femoral fracture (KA-N, LA-N) and intercondylar femoral fracture (KC-N, LC-N)
+ Bending test: Done with 3-point horizontal bending conditions, the distance of 02 bearings is 200 mm, bending position is 3 mm The system of bone plates is fixed horizontally, the machine will create horizontal lateral bending forces with supracondylar (KA-U, LA-U) and intercondylar (KC-U, LC-U) bone cut samples
+ Torsion test: Done with 3-point torsion conditions, the distance of 02 bearings is 200 mm, bending position is
3 mm The system of bone plates is fixed horizontally, the machine will create torsional forces with the 900 axis
with supracondylar (KA-X, LA-X) and intercondylar (KC-X, LC-X) bone cut samples
Tests are designed based on the test
model of Dirk Wähner, assessing
durability of the bone combination means [8, 9], our research model evaluates firm fracture fixation and has a few adaptations suitable to the conditions of experiment in Vietnam
* Method of evaluating results: Plotting
graphs and calculating forces by statistical algorithm of Hanoi University of Science and Technology
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RESULTS
Table 1: Compression force on 2 plate systems - bones with supracondylar and
intercondylar fractures (n = 24)
Plate system - supracondylar (A2) and intercondylar (C2) fracture bones
Compression
force (N)
Fracture
movement
KA-N (Sd) (n = 6)
LA-N (Sd) (n = 6) p
KC-N (Sd) (n = 6)
LC-N (Sd) (n = 6) p
(± 355.90)
1,121.19 (± 230.17)
> 0.05 1,194.51
(± 210.07)
953.97 (± 287,56)
> 0.05
(± 384.83)
1,552.09 (± 256.04)
> 0.05 2,030.63
(± 241.84)
1,597.88 (± 527.67)
> 0.05
(± 641.66)
2,074.99 (± 263.24)
> 0.05 3,140.14
(± 288.16)
2,738.34 (± 703.88)
> 0.05
(± 427.18)
2,865.01 (± 548.70)
> 0.05 3,915.8
(± 295.43)
3,498.13 (± 787.61)
> 0.05
(± 509.50)
3,200.04 (± 243.62)
< 0.05 4,620.27
(± 315.85)
4,139.28 (± 766.53)
> 0.05
The increment of compression force acting on the models of plates - bones on the
two bone fractures of A2 and C2 had no difference in force causing the displacement of
a fracture from 0.5 - 2.0 mm with p > 0.05 But when displacing fracture to 2.5 mm, the
type A2 fracture had a significant change and difference of force acting on the distal
femoral locking compression plate (KA-N): 4,010.37 ± 509.50 N and the condylar
buttress plate - bone (LA-N): 3,200.04 ± 243.62 N with p < 0.05 As for C2 sample, the
force acting on the distal femoral locking compression plate - bone (KC-N): 4,620.27 ±
315.85 N and the condylar buttress plate - bone (LC-N): 4,139.28 ± 766.53 N, the difference was not statistically significant with p > 0.05
Table 2: Bending force on plate systems - fracture bones (type A2 and C2) (n = 24)
Plate system - supracondylar (A2) and intercondylar (C2) fracture bones
Bending force (N)
Fracture
movement
KA-U
(Sd) (n = 6)
LA-U (Sd) (n = 6) p
KC-U (Sd) (n = 6)
LC-U (Sd) (n = 6) p
(± 70.34)
155.86 (± 48.13)
> 0.05 139.43
(± 39.09)
105.3 (± 35.22)
> 0.05
(± 117.52)
314.52 (± 88.88)
> 0.05 271.34
(± 124.77)
216.28 (± 97.57)
> 0.05
(± 121.16)
499.78 (± 85.32)
> 0.05 447.57
(± 107.14)
416.75 (± 134.66)
> 0.05
(± 110.45)
505.76 (± 62.83)
< 0.05 699.26
(± 125.60)
476.05 (± 59.18)
< 0.05
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The increment of bending force displaced plates - bone from 1 - 3 mm on type A2
and type C2 femoral fractures that had a statistically insignificant difference with
p > 0.05 The greater the distortion, the further the difference force increment At 4 mm
level, there was a link breakdown, the horizontal bending force exerted on the distal
femoral locking plate system - bone (KA-U): 704.33 ± 110.45 N was higher than that of
condylar buttress plate - bone (LA-U): 505.76 ± 62.83 N and the force exerted on C2
sample, distal femoral locking plate - bone (KC-U): 699.26 ± 125.60 N was also higher
than that of condylar buttress plate - bone (LC-U): 476.05 ± 59.18 N The difference
was statistically significant with p < 0.05
Table 3: Torsion force on plate systems - fracture bones (type A2 and C2) (n = 24)
Plate system - supracondylar (A2) and intercondylar (C2)
fracture bones
Torsion force (N)
Fracture
movement
KA-X (Sd) (n = 6)
LA-X (Sd) (n = 6) p
KC-X (Sd) (n = 6)
LC-X (Sd) (n = 6) p
(± 54.73)
390.70 (± 81.15)
> 0.05 514.21
(± 135.30)
489.13 (± 81.64)
> 0.05
(± 88.51)
533.90 (± 95.10)
> 0.05 707.42
(± 213.60)
664.43 (± 98.04)
> 0.05
(± 134.66)
686.91 (± 80.48)
> 0.05 829.03
(± 162.50)
826.02 (± 112.04)
> 0.05
(± 166.54)
888.84 (± 89.02)
< 0.05 1,071.00
(± 222.38)
986.26 (± 116.33)
< 0.05
The increment of twisting force acting on the two systems of plate - bone also had a
change when it started with a 1 - 3 mm shift A type A2 fracture acting on the distal
femoral locking compression plate - bone (KA-X): 990.79 ± 166.54 N and condylar
buttress plate (LA-X): 888.84 ± 89.02 N with displacement to 4 mm began to have a
link breakage, the difference was not statistically significant with p > 0.05 With type C2
fracture, the force acting on the distal femoral locking compression plate - bone (KC-X):
1,071.00 ± 222.38 N and the condylar buttress plate (LC-X): 986.26 ± 116.33 N with a
fracture displacement to 4 mm began to have a link breakage, the difference was not
statistically significant with p > 0.05
DISCUSSION
The femur is the longest bone and the
body’s main bearing bone, in which the
distal femur has a diverse, complex
anatomical structure, an unmatched
mechanical and anatomical axis In daily
movement activities, the distal femur is subject to the main forces of compression along the axes, bending force, torsion force or a combination of these forces
Therefore, the facilities used to combine bones for distal femoral fractures must be
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sufficiently stiff to withstand high load
forces, the material must be good to prevent
from fatigue fractures when exercising,
must have flexibility when fixing complex
fractures and have fractures fixed firmly
by using connections with bones [6, 10, 12]
* Evaluation of sturdy fixation capacity
of fractures:
The system of locking plate - bone has
a higher hardness and durability than the
bone condylar buttress plate system
According to Jamie Alexander et al (2015)
[11], axial compression for fracture of
entire distal femur was 4,142.67 ±
178.71 N, hard bone shell bore a
maximum force of 456.64 ± 78.63 N/mm,
maximum axial compression force for
femoral supracondylar fracture was
2,533.57 ± 245.21 N Porous bone shell
was subjected to maximum force of 474.4
± 148.49 N/mm, axial compressive force
for femoral intercondylar fracture was
2,728.83 ± 235.83 N, so the system of
locking plate - bone with supracondylar
compressive force of 4,010 ± 509.50 N
and intercondylar fractures withstood the
maximum compressive force of KC-N:
4,620.27 ± 315.85 N that were higher
than the axial compression for fracture of
entire distal femur
The force increment of bending and
twisting effect on the plate - bone system
of the system of locking plate - bone
in both models of supracondylar and
intercondylar femoral fractures was higher
than that of the system of condylar
buttress plate - bone The bending force
to break down the linkage of the plate -
bone system with a 4 mm shift of the
locking plate - bone (KA-U: 704.33 ± 110.45 N and KC-U: 699.26 ± 125.60 N) was greater than the condylar buttress plate - bone (LA-U: 505.76 ± 62.83 N and LC-U: 476.05 ± 59,18 N) The torsion force with a 4 mm shift to break the linkage of the locking plate - bone (KA-X: 990.79 ± 166.54 N and KC-X: 1,071.00 ± 222.38 N) was also higher than the condylar buttress plate - bone system (LA-X: 888.84 ± 89.02 N and LC-X: 986.26 ± 116.33 N) on the same sample
On the experimental models of compression, bending, torsion of the locking plate - bone system with supracondylar and intercondylar beef femur fractures With intercondylar femoral fracture, compression force KC-N: 4,620.27 ± 315.85 N and twist bending KC-X: 1,071.00 ± 222.38 N of the locking plate - bone system were higher than intercondylar femoral fracture: KA-N: 4,010 ± 509.50 N and KA-X: 990.79 ± 166.54 N, while bending forces were not much different Supracondylar femoral fracture, therefore, some authors had a view that it is possible to combine bone with medullary nail with reverse flow pin, L angle plate, DCS plate [2, 4] , that also achieves therapeutic effect However, with intercondylar femoral fracture, joint breakage, the above-mentioned means
of bone combination revealed many disadvantages, now the authors choose
to combine bones with the distal femoral locking plate and condylar buttress plate
In cases of distal femoral fractures, articular fractures, complex fractures, multiple fragments, fractures in the elderly, fractures in osteoporosis patients, some authors recommend selecting a combination
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of distal femoral locking plate because the
locking plate - bone system withstands a
high compressive, horizontal bending, torsion
force and fixes fractures firmly [8, 9]
CONCLUSION
Studying firm fracture fixation of the
7-hole distal femoral locking compression
plate (intercus locking plate type, German
pure titanium material, screws made from
TiAl6V4 compound), on the type A2 and
C2 fracture test models gave results:
The bond of plate - bone under
compression force of type A2 (KA-N):
4,010.37 ± 509.50 N, type C2: 4,620.27 ±
315.85 N with a 2.5 mm fracture
displacement broke The bond of plate -
bone under horizontal bending force of
type A2 (KA-U): 704.33 ± 110.45 N, type
C2 (KC-U): 699.26 ± 125.60 N with a
4 mm fracture displacement broke The
bond of plate - bone under torsion force of
type A2 (KA-X): 990.79 ± 166.54 N, type
C2 (KC-X): 1,071.00 ± 222.38 N with a
4 mm fracture displacement broke
Comparing on the same testing model of
2 plates with supracondylar fracture and
intercondylar fracture in beef femurs, it
was found that the system of distal
femoral LCP - bone under compression,
and bending force was larger than the
system of condylar buttress plate - bone
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Distal femur fractures of the alderly: Different treatment options in a biomechanical comporation Injury Int J Care Injuried 2011, 42, pp.655-659
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Biomechanical evaluation of periprosthetic refractures following distal femur locking plate fixation Injury Int J Care Injuried 2015, 46, pp.2368-2373
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