Anterior Cruciate Ligament Surgery? What is exactly is an ACL?

Anterior Cruciate Ligament tears, more commonly known as the ACL have become well known in the last few years. The ACL is one of the main ligaments controlling stability in the knee. A ligament is a dense band of connective tissue that connects bone to bone, in this case, it connects and controls movement between the femur and the tibia bone. The word cruciate in fact comes from the Latin word cruci meaning “cross or cross-shaped” as it crosses with another if the knee ligaments (the posterior cruciate ligament).

I’m sure we’ve all heard the tale from a friend, family member, or a famous athlete whose season was cut short ill-timed knee twist and the dreaded “pop” noise. This injury tends to occur more within the female population and with sports requiring landing or pivoting movements (i.e. netball, football, touch, basketball). In the majority of cases, this injury is caused by non-contact movement (i.e. pivoting or rapidly changing direction) rather than direct contact with another person. Non-contact injuries make up a shocking 70% of all cases.

What options do I have?

Broadly speaking there are two options for ACL ruptures – conservative or surgical management. Consideration of the person’s age, the current level of function, and past medical history can be an indicator as to the suitability of either treatment. Generally speaking people with more sedentary and lower physical activity requirements may elect for conservative rehabilitation programs, rather than undoing surgery.

With conservative (non-surgical) management, a program of physiotherapy and rehabilitation is recommended to restore the knee to your previous mobility. With surgical management, rehabilitation takes approximately >9months tailored with a specific physiotherapy exercise program to restore strength and function.

What happens in the surgery?

Essentially ACL reconstructions replace the injured or ruptured ACL. Commonly the surgery is minimally invasive via keyhole or arthroscope. The surgeon will then remove any reminisce of the old ACL and insert the new ACL graft. They will stabilize the graft by drilling this into the bone.

The type of graft is variable as well. Here are a few examples of the types of grafts that can be harvested:

  • Autografts – done from another part of the person body (i.e. Hamstring, Patellar tendon)
  • Allograft – donor from another person (Family member or cadaver)
  • Synthetic – artificial donor.

What can I do right now before surgery?

The main goals of physiotherapy for pre-post ACL reconstruction involve regaining stability within the joint, restoring muscle strength and range of movement, and decrease the risk of re-injury.

A study by Kim,.et. al (2015) looked at pre-operative ACL participants who undertook a four-week knee extensor exercise program. This study found that the exercise group experienced lower post-operative deficits in quadriceps strength and improving single-leg hop distance compared to patients who did not participate in a preoperative exercise program. [3] This study highlights how completing exercise pre-operatively can assist with post-op strengthening and function.

Initial Stages of ACL rupture (~ in the hours to days post rupture)

During this stage, in the first few hours or days after an ACL tear, it is important to aim to minimize the swelling, reduce pain, and begin a gentle range of movement exercises.

These may include:

  1. Gentle heel slides
  2. Static quadriceps exercises
  3. Tummy knee bends

Secondary Stages of ACL Rupture – When the swelling/ pain has subsided

Now that the swelling and pain have resolved it is a good time to begin some more challenging exercises to begin strengthening the knee joint. As your knee is probably feeling pretty weak and wobbly right now

These may include:

  1. Single leg balance: Aiming for 30-sec balance holds with soft knees.
  2. Heel raises: Aiming for a rise time of 1sec and a lower time of 2sec. Aim for 20x reps on each leg
  3. Passive knee extensions: Sometimes using a towel under the towel can be a good way to gain a nice knee/hamstring stretch.

Hewett TE. et al. Anterior Cruciate Ligament Injuries in Female Athletes: Part 1, Mechanisms and Risk Factors. Am J Sports Med. 2006; 34:299-311.

Herrington L, Wrapson C, Matthews M, et al. : Anterior cruciate ligament reconstruction, hamstring versus bone-patella tendon-bone grafts: a systematic literature review of outcome from surgery. Knee, 2005, 12: 41–50.

Kim, D. K., Hwang, J. H., & Park, W. H. (2015). Effects of 4 weeks preoperative exercise on knee extensor strength after anterior cruciate ligament reconstruction. Journal of physical therapy science, 27(9), 2693–2696.


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