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Anatomical Adaptive Device for Fracture Reduction in the Femorotibial Joint
ANATOMICAL ADAPTIVE DEVICE FOR FRACTURE
REDUCTION IN THE FEMOROTIBIAL JOINT
Dan Putineanu PhD. Student MD. Senior Orthopaedic Surgeon 1, Professor Assistant, Comşa Stanca PhD. Eng. 2, Ion
Mihail R&D assist. 2, Pacioga Adrian Eng2.,
1
Floreasca Emergency Hospital, Floreasca Road 8, 1st District, Bucharest, Romania, E-mail: [email protected],
2
National Institute of Research and Development for Mechatronics and Measurement Technique 6-8 Pantelimon Road,
2nd District, Bucharest, Romania, 021631, E-mail: [email protected], [email protected],
[email protected]
Abstract: The goal of surgical treatment in femorotibial fractures is a perfect reduction of the bone
fragments especially when articular surface is involved, the final step being realization of stable fixation.
This enables less painful motion of the knee in the initial postoperative period, while stabilizing the
fracture in the reduced position. Muscle forces acting on the bone fragments often determine their
displacement. Traction alone can restore their normal position, but may result in an axial misalignment,
instead of correcting it. The options available to stabilize these fractures have multiplied during the past
few years, but the main problem remains the correct positioning of the bone fragments in the anatomical
position, followed by the use of screws and implants to provide greater initial stability. Because of the
large forces needed to reposition the bone fragments which are displaced into unexpected positions and
because the fragments must be kept in the right position until the stabilisation is achieved, it is practically
impossible for one orthopaedist to make the fracture reduction, usually two or three specialists being
needed for the procedure completion. That’s why the authors conceived a dedicated device.
Keywords: knee, fracture reduction, anatomical adaptive device.
1. Introduction
In knee fractures, comminution of the articular surface
may be significant, so that an exact reduction is very
difficult. The surgeon must reduce the fracture and
maintain the normal mechanical alignment of the knee.
Fortunately, the knee can tolerate some degree of
articular incongruity, due to the presence of the
meniscal cartilage. The displacement of the bone
fragments into the right position and maintaining this
position requires large forces, so that only one surgeon
is not enough for such a surgery. The presence of two or
three surgeons into the operator field diminishes very
much the working space, making sometimes impossible
realization of the surgical procedure. For this reason the
authors imagined an anatomical adaptive device for
fracture reduction in the femorotibial joint, the device
having the role to realize displacement of fractured
bones into the original position and to maintain it until
the final stabilization is made. Because of the existence
multiple translations and rotations, the device is
adaptive to the various anatomy of each patient in terms
of dimensions and position.
The knee includes the following structures (see Figure 1):
1) Bones:
- femur (thigh bone);
- tibia (shin bone);
- patella (knee-cap).
2) Ligaments:
- medial collateral ligament (MCL);
- lateral collateral ligament (LCL);
- anterior cruciate ligament (ACL);
- posterior cruciate ligament (PCL).
3) Menisci (cartilages):
2. Anatomy of the Knee
The anatomy and function of the knee are quite
complex, and only the basics are described below, in
order to facilitate the understanding of the functionality
of the anatomical adaptive device for fracture reduction.
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Figure 1: Anterior view of the knee structures
- medial meniscus
- lateral meniscus
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2012, No. 42
Anatomical Adaptive Device for Fracture Reduction in the Femorotibial Joint
4) Joint capsule
The glossary at the end of the article explains the
medical terms which are used in this paper.
The tibial plateau articulates with the femoral condyles,
and the patellofemoral groove (located anteriorly
between the femoral condyles) accepts the patella. The
tibia and patella do not articulate. The gliding motion of
the patella across the femur allows smooth extension at
the knee and increases the mechanical advantage of the
quadriceps.
The extra-articular muscle-tendon units include the
quadriceps and patellar tendons (responsible for knee
extension), medial and lateral hamstrings (chiefly
responsible for knee flexion), gastrocnemius muscle,
popliteal ligament and iliotibial band (see Figure 2).
likely to cause a tibial plateau fracture as the weight
drives the femur into the tibia. Twisting and bending
injuries are more common with sports and these can
cause any of the supracondylar fractures depicted above.
In the elderly, supracondylar fractures and plateau
fractures are considered fragility fractures. These
fractures may have occurred as a result of osteoporosis
[2].
a. Patellar
fractures
b.
Supracondy
lar fractures
c. Tibial
plateau and
fibula
fractures
Figure 2.Anterior and posterior views of the muscles
associated with the knee
The extra-articular ligamentous structures include the
tibial and fibular collateral ligaments (see Figure 1).
These ligaments act as the principal extra-articular static
stabilizing structures (i.e., they provide stability for the
medial and lateral aspects of the knee).
The intra-articular structures include the medial and
lateral menisci and the anterior and posterior cruciate
ligaments (see Figure 1). The menisci are
fibrocartilaginous wedges that rim and cushion each
femorotibial articulation. The anterior and posterior
cruciate ligaments provide stability for the knee joint [1].
3. Knee Fracture Types and Treatment
Fractures of the knee are very complex and often
involve articular surfaces. Fractures may occur in the
patella, femoral condyles, tibial plateau or fibula (see
Figure 3.a, b, and c) and can be displaced or
undisplaced.
Large forces are required to fracture the knee joint.
These may be the result of a direct force (e.g. being hit
by the bumper bar of a car, or getting a stop kick to the
knee) or an indirect force (e.g. a sudden contraction of
the thigh muscle can fracture the patella). The two main
mechanisms of patellar fracture are direct trauma to the
anterior aspect of the knee or a powerful contraction of
the quadriceps muscle (transverse, upper pole and lower
pole fractures). Falls from a height would be more
Figure 3: Knee fracture types
For undisplaced fractures of any part of the knee,
immobilization of the knee is an option. This is the
normal treatment for knee fractures, unless ligament
reconstruction surgery is also needed. The cast is
applied from thigh to ankle leaving the foot out of the
cast. If the cast treatment is for an undisplaced
supracondylar fracture or a tibial plateau fracture, the
knee is usually held in 45 degrees flexion inside the
cast. Undisplaced fractures of the kneecap are rare but
may be treated in a cast with the knee straight. Cast
treatment has disadvantages because it makes full
recovery longer (cast immobilization is continued until
healing has occurred) and the fracture fragments may
not be accurately reduced or may displace during the
healing period leading to malunion.
The most popular method of surgical treatment
of knee fractures is the opened reduction with internal
fixation. This means that the fracture site is exposed
through an incision in the skin (open), the fracture
fragments are moved back into the correct position
(reduction) and then held in place by metal implants
such as pins, screws and plates (fixation). The fixation
devices are left on the bone and the wound is closed [2].
The main problem in this case is the displacement of the
bone fragments into the normal position, because as
described above, in the knee joint the muscles and
ligaments tends to move the fragments in to unexpected
positions once the bone has been broken. Large forces
are often needed in order to bring back into original
position these fragments and maintain this position until
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2012, No. 42
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Anatomical Adaptive Device for Fracture Reduction in the Femorotibial Joint
the fixation is completed. That’s why the specialists
from INCDMTM in collaboration with a Senior
Orthopaedic Surgeon from Floreasca Emergency
Hospital designed and manufactured the anatomical
adaptive device for fracture reduction in the
femorotibial joint which is described below.
4. Description of the device
reduced, paying particular attention to the joint surface.
If there are small bone fragments, these must be
removed. Only the large fragments are taken into
account and the size of these fragments should allow
screwing the threaded K wire with diamond tip and
single end (see Figure 5). If parts of the joint surface
which are broken were pushed inside the bone, these
fragments need to be lifted up, or elevated, and held in
position until fixation is done.
The conception of the device and its components are
presented in figure 4.
Figure 5: Kirschner threaded wire with diamond tip and
single end
Figure 4: Anatomical adaptive device for fracture
reduction in the femorotibial joint
The device consists of the following main items:
1. Base plate. Through it, the device is rigidly
attached to the operating table, and its length
ensures the possibility of adaptation to the specific
dimensions of the patient anatomy.
2. Oval holes. They are provided in order to make the
necessary adjustments according to the joint size.
3. Knob to adjust the distance between the two pillars
according to the joint size. By loosening those
knobs, the orthopaedist moves the two pillars
depending on the joint size.
4. Vertical pillar. It sustains the orientation (X, Y, Z)
and lock in position mechanism.
5. Kirschner threaded wire with diamond tip and
single end. The threaded end is inserted in the bone
fragment which must be displaced in to the original
position.
6. Knob for adjusting the distance on the X axis
direction. Using this knob, the surgeon moves
(rotation, translation) the bone fragment in the
desired position on X axis direction and locks the K
threaded wire in the desired position.
7. Knob for adjusting the distance on the Y axis
direction.
8. Knob for adjusting the distance on the Z axis
direction.
The surgical protocol depends on the anatomy
of the fracture, but in most cases the broken bone is
exposed. Exposing a fracture means that an incision is
made and enough of the tissue surrounding the fracture
is moved aside so that the fracture can be seen good
enough to repair it. The fracture fragments are then
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First, the anatomical adaptive device is mounted on the
operating table and after securing it the surgeon adapts
the distance between the two vertical pillars according
to the patient size and locks them into position. After
the K wire is inserted into the bone fragment which
must be repositioned, the surgeon uses the other end of
the wire which acts as a joystick. The orthopaedist uses
the four degrees of freedom of the anatomical adaptive
device (three rotations and one translation) in order to
move the bone fragment into the functional position and
then the fragment is locked in this position using the
dedicated knobs of the device. Sometimes a pointed
reduction forceps can be useful, as rotational control of
the bone is also needed. A special attention is accorded
to any intra-articular fragments, which must be reduced
accurately and fixed with pins or screws in order to
ensure that the joint surface is restored to smoothness.
After bone fragment positioning, before definitive
fixation is inserted, the fracture is clamped. Usually, one
to two K-wires are inserted for provisional fixation. In
this stage, it is very important to check the
biomechanical axis of the lower limb. The normal
biomechanical axis follows a line from the center of the
femoral head, through the center of the proximal tibia
and then through the center of the ankle joint. This axis
should be checked intraoperatively, to give an
approximate estimate of the axis (see Figure 6).
Figure 6: Checking the biomechanical axis of the lower
limb
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Anatomical Adaptive Device for Fracture Reduction in the Femorotibial Joint
Before definitive fixation, the correct position of the
nail/plate and the rotation of the femur must also be
verified. Not only the biomechanical axis must be
restored, but care should be taken to ensure that there is
no accidental rotation between the proximal and the
distal end of bone [3].
The final fixation can be made using nail or plates.
Regardless the type of fixation used (nails or plates), the
fixing device should extend up/down to the intact part
of the bone and fixed with transverse screws. The
fractured part of the bone is also fixed to the nail/plate.
Thus all fracture fragments are held immobile and in
good position by the fixing device and fixation is
obtained above and below the fracture site.
If there are more bone fragments (comminuted fracture),
this reduction procedure is repeated as many times as
necessary, for each pair of bone fragments which are
displaced from their original position. If necessary, bone
graft can be used to add support for the depressed
fragments [4].
The manufactured functional model of the anatomical
adaptive device for fracture reduction in the
femorotibial joint is presented in figure 7.a. and a detail
with the orientation and lock into position mechanism is
shown in figure 7.b.
a. Overall view
b. Detail of the orientation mechanism
Figure 7: Functional model of the anatomical adaptive device for fracture reduction in the femorotibial joint
The device is all stainless steel, and was used by the
M.D. of the research team (who is a senior orthopaedic
surgeon) for some experiments on cadavers. The
obtained results were very promising opening the way
for the clinical use of the device. During these
experiments, studies were made in order to see if this
adaptive device can be utilized for indirect reduction of
the fracture fragments with minimal exposure
(minimally invasive technique). According to this
technique, the fracture site is not entirely exposed, the
fixing device being slid up under the muscle and the
screws being inserted through small incisions into the
skin, so that the blood supply is not disturbed. The
results were also satisfactory, but in this case, the
experiments were carried out under image intensifier
guidance, producing high quality intraoperative images
in order to ensure correct reposition of the bone
fragments.
Considering these results, the research team aims to
patent the device and to obtain medical certification, so
that that it could be soon used into current medical
practice.
5. Glossary
Anterior - Situated at the front;
Extension - Moving a limb so that the two posts are
straightened;
Flexion - Moving a limb so that the two parts are bent;
Fracture - Broken or cracked bone;
Comminuted (fracture): A fracture in which the bone
has broken into a number of pieces;
Invasive (procedure): when a break in the skin is
created and there is direct contact with the mucosa, or
internal body cavity;
Lateral - A position away from the centre of the body
(opposite to "medial");
Medial - A position toward the centre of the body;
Posterior - Situated at the back;
Meniscus - Cartilage inside knee joint;
Rotation - Twisting.
6. References
[1] Howard, B., Tandeter, Pesach Shvartzman: “Acute
Knee Injuries: Use of Decision Rules for Selective
Radiograph Ordering” American Family Physician,
1999 Dec 1;60(9):2599-2608.
[2] ***:
“Adult
knee
fractures”,
http://www.eorthopod.com/content/adult-knee-fractures
[3] Florian Gebhard, Phil Kregor, Chris Oliver:
“Retrograde Nailing
of the Distal Femur”, AO
Foundation References, Online reference in clinical life,
https://www2.aofoundation.org/wps/portal/surgery?sho
wPage=redfix&bone=Femur&segment=Distal&classific
ation=33-C2
[4] S., Vidyadhara, Carlos, J., Lavernia: “Tibial Plateau
Fractures Treatment & Management”, Medscape
Reference,
http://emedicine.medscape.com/article/1249872-treatment
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