Anterior Cruciate Ligament (ACL) reconstruction

Date: 05 Aug 2015

The ACL is a ligament that connects the femur (thigh bone) to the tibia (shin bone) forming the knee joint. The ACL is one of 4 major ligaments contributing to stability of the knee. It is also the commonest ligament to rupture, especially in today’s active sporting lifestyle. The ACL does not need direct contact to rupture.

There are some who are fortunate to be able to return to pivoting sports (turning and changing directions) without an ACL. Many, however, find it difficult to participate in pivoting sports without an ACL, with the knee feeling unstable (and giving way) or having no confidence in the knee.

What is an ACL reconstruction?

A knee reconstruction is a term used to describe replacing a torn ligament with a new one. In the adult knee, a ligament repair (with stitches) often fails and this is now abandoned for ACL tears. Thus, the surgeon will harvest a graft of your own tissue (like hamstrings – don’t worry, it will not make your knee weaker, or patella tendon along with a small piece of adjacent bone). Alternatively, a synthetic graft may be used in conjunction or as a stand-alone replacement.

What do you do prior to surgery?

Pre-habilitation is a term used to describe maximizing knee strength and motion before undergoing ACL reconstruction. This is frequently neglected but its effects outlined in the American Journal of Sports Medicine in September 2013, “Effect of pre-habilitation on the outcome of anterior cruciate ligament reconstruction”, proves advantageous in post-operative outcomes, and a faster rehabilitation.

What is the surgery?

The surgery is an arthroscopic (keyhole) procedure that takes an hour to perform. This includes, harvesting the graft, cleaning any debris from inside the knee, repairing or trimming any torn meniscus/ cartilage, and performing the ACL procedure. The ACL surgery consists of drilling a bone tunnel inside the femur and tibia bones and passing the new ligament in the line of the native ACL. This is secured by special screws, staples or a specially made device.

How long before returning to sport?

This will depend on achieving the goals of rehabilitation to a certain degree. However, in hamstring reconstructions, the limiting factor is that the strength of the graft takes more than 6 months to mature and to have enough stiffness and durability to withstand the forces of full pivoting sports.

Risk of re-rupture

Unfortunately, there is a risk of graft re-rupture upon return to sports. This is very low and return to previous level of function is very high for anatomic ACL reconstruction. American Journal of Sports Medicine in May 2015 reviewed numerous studies. “Comparison of Graft Failure Rate between Autografts Placed via an Anatomic Anterior Cruciate Ligament Reconstruction Technique: A Systematic Review, Meta-analysis, and Meta-regression.” The overall re-rupture rate for hamstring graft is 4%.

Your surgeon at SWSO will discuss any concerns you may have regarding your ACL injury and the best course of management for your knee.

By Dr Ray Chin, MBBS, FRACS (orth)

Consultant orthopaedic surgeon at South West Sydney Orthopaedics

Director of orthopaedic training at Liverpool Hospital

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