Dear Editor,
The following is a Technical Explanation for a Lay Audience about the process of
Anterior Cruciate Ligament reconstructive surgery. I expected this TELA to be
published in your Sports Science magazine. Because of this the intended audience
for the article is doctors and athletes who wish to learn more about this surgery.
The overall format for this article is ‘compare and contrast’. It is meant to compare
the pros and cons of each of the different types of reconstructive surgery available.
I wish to publish this article in your magazine because I think it will greatly benefit
the sports community, by giving those that suffer from this injury a better chance at
recovery. Also a better understanding of each procedure will better equip the
doctors who wish to perform this surgery.
Please consider this article in the next publication of your magazine.
Anterior Cruciate Ligament Reconstruction
What is the purpose of the Anterior Cruciate Ligament (ACL), especially to
athletes participating in high-impact sports? The ACL is a very important ligament
for proper knee movement and stability. A tear in the ACL is a very serious injury
and reconstructive surgery is very important to athletes that wish to return to the
sport.
Background:
The ACL is one of four major ligaments in the knee: Medial Collateral
Ligament (MCL), Lateral Collateral Ligament (LCL), ACL, and Posterior Cruciate
Ligament (PCL). The ACL connects the tibia, also known as the shinbone, to the
medial meniscus- that in turn is connected to the femur. The ACL prevents the tibia
from rotating or sliding forward during agility, running, or jumping movements.
Tearing of the ACL usually is termed “the terrible triad” because it usually consists
of simultaneous tearing of the ACL, medial collateral ligament (MCL), and medial
meniscus. ACL Tears are one of the most common knee injuries and are often a
result of landing or planting in cutting or pivoting sports.
When undergoing ACL reconstruction the selection of what ‘graft’ to use is
the most important decision and contributes most to the ‘success’ of the operation.
There are two types of ‘grafts’ available: Patellar Tendon Autografts and FreshFrozen Patellar Tendon Allografts. Autografts essentially use bone or tissue that has
been harvested from the patient’s body; whole Allografts use bone or tissue from a
‘donors’ body, typically a cadaver’s body. The choice between the two options
depends on the age and lifestyle of the patient. The study being discussed compares
autograft and allograft ligament reconstruction in goats, and can be used to
determine which graft is better for athletes who wish to rejoin their sport.
The Experiment:
The following is an experiment that was performed on goats with ACL tears
to determine which of the two grafts had a higher success rate. For each graft type
20 goats underwent the surgery (20 autografts and 20 allografts), and all donors
were matched for age, sex, weight, and height to the recipient. The surgical
procedure is the same for each graft: exposing and removing the torn ACL then
creating ‘bone-tunnels’ in both the tibia and femur for the new ligaments to be
grafted into, all grafts were placed under ‘tension’ in the knee. A Lachman test is
then administered- resistance to approximately 7 pounds of force and full range of
motion test. Six weeks after the surgery a battery of tests were run: anteriorposterior translation, degenerative changes, and mechanical properties; this test
was then run again after 6 months.
The Anterior-Posterior translation test includes a range of motion test and
loading test. In this experiment a load of 50N was applied to the tibia, a
measurement of anterior-posterior displacement from midline was taken to graph
load versus displacement curve. ‘Stiffness’ of the joint can then be calculated at a
certain load by taking the tangent to the curve.
Degenerative articular cartilage change test is basically an examination of the
knee. The knee is divided into nine anatomic areas and given a graded score for
degenerative changes. This change is compared to goats that have torn their ACL but
did not undergo reconstructive surgery. The examiner is unbiased to the type of
graft performed, and all goats experienced the same amount of maintenance during
recovery. At both the 6-week and 6-month mark, the articular cartilage in the
allograft and autograft reconstruction groups showed minimal increase in changes,
compared to the control knee. Meaning that neither is favorable.
Mechanical testing placed the tibia and femur at 30 of flexion and at full
extension. Tensile failure tests were then conducted and measurements of the
displacement of the bones were taken. The test allowed us the following
information: ligament stiffness in linear loading, maximum force of the femur-ACLtibia before failure, and energy and elongation till maximum force. At 6-months after
the surgery strengths of the allografts and autografts were 27% and 62% of the
control ACL strength, respectively.
The Results:
Based on the information gathered from each test, after six months, the graft
with the highest success is allografts. However, this is based on time of
rehabilitation, after a longer period autografts proofed to be better. Therefore the
overall conclusion is that both grafts have different strengths and weaknesses, and
the selection of a graft should depend on the patient’s lifestyle. If the patient wishes
to continue a career in sports an allograft is recommended. If the patient has a low
impact lifestyle, either graft is acceptable.