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.

• 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

Are ACL tears common?

• ACL tears are very common. The highest occurrence (incidence) is in individuals between 15 to 25 years of age, who participate in pivoting sports (like soccer and football). However, ACL tears can occur at all ages and in all sporting activities.

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

 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.

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 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

What are the goals of anatomic ACL reconstruction? 

• To restore 80-90% of native ACL anatomy

• To maintain a long term knee health

Do we perform anatomic single bundle ACL reconstruction?

• Yes – we perform single bundle ACL reconstruction in approximately 30% of our patients.

• There are a few 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.

• We carefully investigate the rupture pattern of the ACL and identify the native ACL insertion sites.

• The tibial and femoral bone tunnels are then drilled in a matched anatomic fashion. (See pictures below)

• Previous single bundle techniques often utilized a PL to High AM, which led to impingement of the graft. The AM to AM approach leads to a more anatomical reconstruction. Today, we prefer to use a more anatomical approach with 50% middle tibial insertion to 50% middle femoral insertion.

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

Dr. Prateek Gupta
C2/5 Safdarjung Development Area (SDA),
Aurobindo Marg,
Newdelhi, India
Mobile : + 91 9810852876
For Appointment & 24 x 7 Helpline no: + 91 9810633876