Anatomic
Double-Bundle ACL Reconstruction
Patient
Information Handout / Frequently Asked Questions
Freddie H. Fu, MD, DSc (Hon), DPs (Hon)
Marvin Y. Lo, MD
Brian Forsythe, MD
Updated: 03/10/2009
What is the ACL and what does it
do?
§
The
anterior cruciate ligament (ACL) connects the femur bone to the tibia bone in
the center of the knee joint. (Ligaments connect bones to bones.)
§
When
athletes “blow out” their knees – this is the ligament that is commonly torn.
§
The
ACL is important during daily activities but absolutely critical
to the stability of the knee during sports.
What is the native anatomy of
the ACL?
§
The
ACL is made up of two functional bundles of tissue, the anteromedial (AM) and
posterolateral (PL) bundles. These bundles are first seen during fetal
development and persist throughout life. [1]
§
The AM
bundle of the ACL primarily controls anterior (forward) movement of the tibia
underneath the femur, and the PL bundle controls rotational stability of the
knee, such as in pivoting, twisting, running, and jumping. [9,10]
§
In
other words, each bundle has a different function, and this is reflected in the
anatomy. When the knee is straight the AM and PL bundles are parallel. As the
knee is flexed, the two bundles cross each other:
§
Here
is a closer look at the femoral attachment sites – we can see the upper margin
of the ACL attachment site (intercondylar ridge) and the bifurcate ridge (probe
on ridge) which separates the insertion sites of both the AM and PL bundles.
§
Interestingly
– different animals have different numbers of ACL bundles – likely a reflection
of Darwinian selection.
§
This
is seen in both the bone and soft tissues. Above is a comparison of the human
bony ridge (left) for the ACL insertion, and on the right is the bony ridge of
the ACL in monkeys – reflecting different ACL bundles.
§
Here
is a goat with 3 bundles on the left, and a rhesus monkey also with 3 bundles
on the right.
§
Here
are some normal human knees showing both the AM and PL bundles of the ACL - on
MRI scan and during arthroscopy:
Are ACL tears common?
§
ACL
tears are very common. Over 200,000 ACL tears occur each year in the
How is an ACL tear diagnosed?
§
Tear
of the ACL can be diagnosed by a history of trauma to the knee (contact or
non-contact) and physical examination. MRI scan can confirm the diagnosis:
§
At the
time of arthroscopic surgery, severe stretching or complete tearing of the AM
and PL bundles of the ACL may be observed, as pictured below:
Is surgery absolutely necessary
for my ACL tear?
§
No.
There are some patients who are able to function without an intact ACL. These
patients modify their activity, by eliminating pivoting and cutting movements
and sports, in order to minimize subluxation, or “giving away” episodes.
However, sometimes during regular activities the ACL-deficient knee can buckle
or “give way” (subluxate) resulting in painful episodes with swelling.
§
Importantly,
there is a risk for damage to the menisci (cartilage shock absorbers) and
articular coating cartilage inside the knee joint with each subluxation event.
This damage can lead to degenerative arthritis.
§
Because
of these concerns, a majority of active patients elect to undergo ACL surgery
when the ligament tears.
Can the ACL be repaired or does
it have to be reconstructed?
In
general, the fibers of the ACL can not be sewn back together again (or repaired
‘primarily’). This is due to irreversible stretching and damage to the ligament
sustained at the time of injury. Therefore, damaged ligaments are removed and
replaced with new ones.
I just tore my ACL—when will I
be ready for surgery?
§
In
general, there are three criteria that must be met before the ACL can be
surgically reconstructed:
1) Swelling in the knee must go down to
near-normal
2) Range-of-motion (flexion and extension) of
the injured knee must be nearly equal to the uninjured knee
3) Good Quadriceps muscle control must be
present (able to do a straight-leg raise)
§
Usually
it takes a couple of weeks after injury before ACL reconstruction can be
performed.
§
The
presence of any associated injuries to the knee joint involving cartilage,
meniscus, or other ligaments may change the time-frame for surgery.
What are the key principles and
concepts to consider when thinking about ACL reconstruction? What is an anatomic
reconstruction, and what is a double bundle reconstruction?
§
Anatomic
reconstruction - everybody has different anatomy – therefore in order to properly
reconstruct the ACL – it is important to reproduce each individual’s native
anatomy. Our philosophy is to match the ACL graft sizes to the patient’s native
anatomy, which means that the ACL tunnel placement, size, and tensioning
patterns are restored to reproduce normal knee stability and function.
What are the goals of anatomic
ACL reconstruction?
§
To
restore 80-90% of native ACL anatomy
§
To
maintain a long term knee health
What surgical techniques are
used for ACL reconstruction?
§
A
standard technique of ACL surgery during a “single bundle” reconstruction
involves removing a piece of bone and cartilage. This is called a
“notchplasty.” A drill guide is then used to drill a single tunnel on both the
tibia and femur. A single ACL graft is then passed through the tunnels.
My Simple and Efficient ACL Reconstruction 1989 – 2002
§
Historically,
this standard technique provides good results. At UPMC, we have performed over
5000 Single-Bundle ACL reconstructions in this manner, from 1982-2003.
§
However,
instead of reproducing the native anatomy, this traditional method may result
in a tunnel “mismatch”. In another word, instead of connecting the tibial AM
site (A) to femoral AM site (A) and tibial PL site (B) to femoral PL site (B),
it may produce some kind of mismatch by connecting tibial PL site (B) to
femoral AM site (A), or tibial PL site (B) to a high AM site (high). The
pictures below illustrate a few of the “mismatch” combinations.
§
Since
2003, we have changed our approach by utilizing the concept of anatomic
reconstruction. By avoiding a “notchplasty,” we preserve more of the native ACL
anatomy- the bony ridges and soft tissues. This allows us to more accurately
reproduce the two native AM and PL bundle insertions on both the femoral and
tibial bones, and connecting the bundles from A to A, and from B to B.
§
At
UPMC, we have performed over 500 anatomic Double-Bundle ACL reconstructions
since 2003, with excellent results. [20]
Why is Anatomic
Double-Bundle ACL reconstruction performed instead of Single-Bundle?
There
is a significant amount of scientific evidence supporting double bundle surgery:
§
The
ACL is composed of two functional bundles, the anteromedial (AM) bundle and the
posterolateral (PL) bundle, not just one. [1]
§
Between
10% and 30% of patients complain of pain and residual instability following
Single-Bundle ACL reconstruction. [2-7]
§
Arthritis
has been observed on x-rays in up to 90% of patients at long-term follow-up
after Single-Bundle ACL reconstruction. [8]
§
Single-Bundle
ACL reconstruction does not adequately restore normal knee stability,
particularly tibial rotation [11-16]
§
Anatomic
Double-Bundle reconstruction better restores knee stability compared to Single-Bundle
reconstruction. [12,14,16,17]
To
better understand how “Double-Bundle” ACL reconstruction has evolved from
“Single-Bundle” surgery, one should consider a door hinge. A door with one
hinge is like a Single-Bundle reconstruction—it will open and close, but the
hinge is required to work excessively. Over time the hinge will loosen and the
door will wobble. In comparison, a Double-Bundle reconstruction is like a door
with two or three hinges. The work is shared between the hinges, and the door
can open and close smoothly for long periods of time without falling apart. One
hinge doors were used in log cabins, while in medieval times two hinges were
used. Today’s doors have three hinges, representing an evolution in design.
The Principle of
Anatomic Reduction in Orthopedic Surgery
§
Reproducing
anatomy is essential to the treatment of broken bones. Below is an example of a
broken fibula bone, along with a dislocated ankle. After restoring the fibula’s
anatomy with a metal plate and screws, the dislocated ankle is subsequently
relocated. The anatomy and function of the ankle joint are thus restored.
§
Anatomic
ACL reconstruction shares this principle: by restoring the ACL with
anatomically placed AM and PL bundles, the knee joint’s anatomy and alignment
are restored. The knee should function just as well as the reconstructed ankle,
by following the principle of anatomic reduction.
The Principle of anatomic double bundle ACL reconstruction surgery
§
Our
objective is to reproduce the anatomy of the ACL by reconstructing both the AM
and PL bundles.
§
We
reproduce the insertion sites of the ACL by identifying and measuring them via
careful dissection. Bone tunnels for the new ligaments are thus placed
precisely where they belong.
§
The AM
and PL bundles of the ACL are differentially tightened to reproduce the normal
tensioning pattern of the ACL.
§
A La
Carte surgery (i.e. individualizing each surgery for each patient)
§
As shown
above, the tibial insertion sites between two patients are markedly different -
17mm on the left, and only 12mm on the right. Our approach is to tailor the ACL
reconstruction to the respective sizes measured at the time of surgery.
What are the details of the surgery?
§
For
ACL reconstruction, we typically use four small incisions:
o Three arthroscopic incisions:
o
One
tibial incision for the bone tunnels
o
Occasionally,
an additional incision is made on the lateral (outer) aspect of the knee joint
over the femur to help secure the grafts.
§
ACL
reconstruction usually takes 60 to 90 minutes.
§
First,
the insertion sites of both bundles (AM and PL) of the old ACL are marked on
the femur and tibia.
§
The
injured ACL is then removed with arthroscopic equipment.
§ The insertion sites of the AM and PL bundle are measured to decide what graft size to use for each patient.
- Care is taken to place the new tissue grafts in the exact position of the original bundles of the ACL, creating an “Anatomic” reconstruction.
- For each
bundle of graft tissue (AM and PL) one tunnel is created in the femur and
one in the tibia (total = 4).
- Each tunnel
measures anywhere from 5 to 9mm in diameter, and this dictates final graft
size
- Tunnels are
created by drilling over guide wires, and sutures are passed.
- The grafts
are then passed through the tunnels and fixed to the femur and tibia with
a combination of special fasteners, screws and sometimes staples:
§
MRI,
CT scan, & X-rays demonstrating the Double-Bundle
ACL reconstruction:
- After Double-Bundle reconstruction, most patients achieve excellent range-of-motion, typically equal to the other knee. These results are typically realized as early as 1 to 3 months after surgery:
Is it possible to tear just one
bundle?
§
Yes –
this is rare but does happen
§
Clinically
an isolated tear of the:
- AM bundle leads to anterior-posterior instability
- PL bundle leads to rotatory instability
§
In either
case we save the intact bundle and “augment” the ACL with a single bundle
reconstruction – either the AM or PL… whichever one is torn
§
On the
left is a picture of a PL intact, AM (only) reconstruction
§
On the
right is a picture of a AM intact PL (only) reconstruction
Do we perform single bundle ACL
reconstruction?
§
Yes –
we perform single bundle ACL reconstruction in approximately 30 % of our
patients.
§
Except
for the one bundle tear described above, there are a few other scenarios where
we prefer to perform single bundle surgery:
- Patient has a very small native ACL insertion
site. This typically can only
determined at the time of surgery
- Patient is still growing and his or her growth plate is
not closed
- Patient has severe arthritis
- Patient with multiple knee ligament injuries or knee
dislocation
- Severe bone bruising and narrow intercondylar notch
- Patients who cannot wait 9-12 months
to return to sports
- Professional or highly competitive
athletes
Is anatomic single-bundle
ACL reconstruction technique the same as had been performed years ago?
§
No, we have learned a great deal from our
development of the double-bundle technique.
We use these principles to perform a “Matched Anatomic Single Bundle” ACL reconstruction.
§
Just
as with double-bundle ACL technique, we carefully investigate the rupture
pattern of the ACL and we identify the native ACL insertion sites.
§ The tibial and femoral bone tunnels are then drilled in a matched anatomic fashion. (See picture on the right)
§
Advantages of “Matched Anatomic” Single
Bundle ACL Reconstruction
Can be performed with various autograft options
§
Bone-patellar tendon- bone (BPTB)
§
Hamstring
tendons
§
Quadriceps tendon (single tunnel on thigh
bone, single or double tunnel on shin bone)
- Allows for faster biologic healing and earlier return to full activity (6months)
§
Limitations of “Matched Anatomic” Single
Bundle ACL Reconstruction
- Cannot
fully recreate the entire ACL
- 65-85% of
the ACL insertion site is typically recreated
- Use of
autograft = additional surgery
- Slightly
longer operative time
- More
pain and discomfort compared to allograft surgery
- Is enough
to return to sports quickly, but may still be some slightly higher risk
of later arthritis.
Where do the grafts for ACL
reconstruction come from?
§
The
graft tissue can come from your own body (autograft) or from a cadaver
(allograft). We most commonly use Hamstring Tendon when autograft is used.
§
Disadvantages
to autograft primarily relate to harvest-site morbidity and increased operative
time.
§
Multiple
types of allograft tissue are commonly used including Hamstring tendon,
Tibialis tendon, and Achilles tendon.
§
Allograft
tissue is comprehensively screened by tissue banks for diseases such as
Hepatitis and HIV. Overall, it is a safe option for graft tissue and disease
transmission is very uncommon. [19]
§
For
Double-Bundle ACL reconstruction, allograft tissue is commonly used as it
provides more flexibility in terms of graft size and length.
Postoperative
Instructions:
How
do I take care of my surgical incisions after surgery?
- The
Cryocuff and wound dressings should be left on for 48 hours
- After
48 hours:
o
Remove
the wound dressing and apply clean band-aids over the incisions. Do not apply
any cream, ointments, lotions or other substances to your incisions.
o
Use
the Cryocuff as needed for swelling, 3 to 5 times a day for 20 minutes
o
You
may shower as long as you keep your incisions dry. Do not soak or submerge your incisions under
water. When dry apply new band-aids daily.
What should I
be aware of after surgery?
The signs and symptoms of wound infection and deep
venous thrombosis (DVT, clots of the leg veins), should be paid close attention
to after surgery. Although rare, these complications can be very serious.
If you experience any of the following symptoms
after surgery, call our office immediately at 412-432-3611, or go to the
nearest Emergency Room for immediate evaluation:
- Fever
(>101.5˚F)
- Chills
- Excessive redness or
swelling around the incision
- Yellow drainage (Pus)
from the incision
- Deep pain and/or
excessive swelling in the calf
- Chest pain, shortness
of breath, or pain with breathing
When do I
follow-up after my surgery?
- After
surgery, you will be evaluated in the clinic at 1 week, 1 month, 3 months,
6 months, 12 months, 18 months, and 24 months.
- A
physical examination will be performed at each visit, measuring knee
range-of-motion and stability. Radiographs of the knee will also be taken
periodically.
How long do I
have to wear my brace?
In
most cases, a hinged-knee brace will be required for 6 weeks after surgery.
How long do I
have to use crutches?
In most cases, crutches will be required for 4
weeks after surgery. This may vary if additional surgical procedures are
performed on the meniscus, cartilage, or other knee ligaments.
How much weight
can I put on my leg after surgery?
In most cases, full weight-bearing is permitted
immediately with the use of crutches. This may vary if additional surgical
procedures are performed on the meniscus, cartilage or other knee ligaments.
What is a CPM
machine, and how often do I have to use it?
- A
CPM machine is a Continuous Passive Motion device. It straightens and
bends the knee immediately after surgery, until adequate muscle control
and range-of-motion is regained.
- Typically,
the CPM is initially set from 0 to 45 degrees and used 2 times daily for 2
hours each time. The flexion is increased 10 degrees a day until
range-of-motion from 0 to 120 degrees is achieved. This typically occurs
over 2-3 weeks after surgery, at which point the CPM can be discontinued.
When do I start
Physical Therapy?
A
prescription for Physical Therapy is given at the first postoperative visit.
The schedule is 1X / Week for 6 weeks, then 2-3 X / Week for 6 - 9 months. A
detailed rehabilitation protocol is provided to the Physical Therapist for
Double-Bundle ACL reconstruction.
When can I
drive?
Driving
is permitted after:
- 1 week for left knee
surgery (automatic transmission)
- 6 weeks for left knee
surgery (manual transmission)
- 6 weeks for right
knee surgery (manual or automatic transmission)
When can I
return to competitive sports?
After
Double-Bundle ACL reconstruction, rehabilitation guidelines are usually as
follows:
- Day of Surgery:
Walking with crutches
- 1 Month: Discontinue
crutches
- 1.5 Months: Discontinue brace
- 3 Months: Jogging /
Running In-Line
- 6 Months:
Sport-specific agility training
- 9-12 Months: Return
to competitive sports
- A functional knee brace
is often recommended for 1 year after return to sports
11/08: All images
are from Dr. Freddie Fu’s patients,
Contact
Information:
Phone: Appointment: 412.687.3900
Email: arrisherlm@upmc.edu
Frequently
Asked Questions:
Why
bother with an “anatomic” or “double-bundle” reconstruction if it takes longer,
with respect to operating time and time to return to sports?
This method of
ACL reconstruction (anatomic) regardless of whether we do single (30%) or
double bundle surgery is meant to reproduce YOUR OWN ACL, both in regard to
ligament placement and ligament size. We believe that this more closely
reproduces “your” native anatomy. The analogy is akin to a suit. Why wouldn’t
you want a custom tailored hand-made suit versus “off the rack”… even if it
takes longer to make?
What happens
to the knee joint if anatomy is not restored?
This entire
discussion is a “game of millimeters”. The answer to this should be considered
in two stages: the short term and the long term.
In the short
term – a well-placed ACL reconstruction allows good restraint to both AP and
rotational stability. This “macro-stabilization” allows patients to feel stable
both subjectively and objectively and is key to returning to sports at a high
level.
In the long
term – subtle or “micro” motion about the knee likely accounts for the increased
incidence of early arthritis in the affected knee (in addition to the damage
from the initial trauma to that knee). Because my bone and ligament anatomy is
different from yours, the forces across my ACL will be different. Because of
this variation, a ligament meant for me will not work as well for you. Although
this may be close enough to reproduce the “macro-stability” mentioned above,
this will not stabilize the micro-motion that occurs around the knee in the
long term.
Again, this is
a game of millimeters and also the subject of millions of dollars in research
today. We have been and are continuing to study this in an effort to continue
to improve both our methods and your outcomes – both short and long term.
What
is the main advantage of a double bundle reconstruction?
More precision
in regards to the ACL reconstruction. You were born with 2 bundles, why would
you want a reconstruction that only replaces one of them?
Do we
do a double bundle reconstruction in every patient with a torn ACL?
No, we don’t.
We perform single bundle ACL surgery on 30% of patients. There are cases
(taking the rest of the knee and patient into account) where single bundle is
better: 1) too small of a knee to safely place two bundles (technical issue),
2) Open growth plates 3) severe arthritic changes, 4) multiple ligament
surgery. Again, your ACL surgery should be what is best for YOU as a patient
and this includes age, activity level, bony anatomy, size of knee, open vs.
closed growth plates, etc….
Is allograft, donor tissue safe?
Long
answer - Nothing is ever 100% safe. There are risks to allograft and they
include a possible risk of disease transmission. The often quoted numbers
include risk of HIV transmission which is 1 in 1.6 million and hepatitis C
which is 1 in 421,000.
A
recent of survery of the AOSSM (sports academy) in 2006 showed that 86% of the
surveyed surgeons use allografts – so they are very commonly used in the sports
medicine world.
Short
answer – Yes allograft is safe. Your risk of being struck by lightening is
higher (73 people are struck and die each year from lightening!) than your risk
of contracting disease from allograft tissue.
Is allograft, donor tissue durable?
Yes.
Both autograft and allograft undergo a process of ligamentization whereby the
body’s own tissue remodels the graft. During the remodeling phase, the graft
itself becomes weaker before regaining its strength. However, the athlete feels
great and so will want to be more aggressive with his/her knee. It is
imperative not to return too soon as this puts “our” grafts in danger. The use
of allograft does require a longer time for biological healing.
When
can I go back to Sports?
Generally,
jogging begins at 3-4 months after surgery. Sport specific training begins at 6
months. Return to competition is allowed at 9-12 months following surgery.
Remember, returning earlier increases the chances of ACL re-rupture. Although
you may feel fine otherwise, biologically, the ACL graft takes about 9 months
to heal.
Is
rehab any different after a double bundle reconstruction?
No. All
aspects of rehab are the same for single and double bundle ACL surgery.
If
I’ve already failed a previous ACL reconstruction, can I still do a double
bundle ACL reconstruction on my knee?
Yes. In fact,
if you’ve already failed single bundle ACL reconstruction, a double bundle
reconstruction is a very good option since it provides more rotational
stability.
Acknowledgement: We would like to thank Drs. Jay
Irrgang, Eric Kropf, Margaret Lo, Sam Robinson, Mathew Pombo, Alexis Colvin,
Wei Shen, and Ms. Rebecca Singleton for their help in preparing this handout.
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1263-74.
The
goal is to restore native insertion sites and the native anatomy of the ACL.
