Anterior cruciate ligament (ACL) surgery is the most appropriate long-term treatment for some ACL tears that are not expected to heal on their own.

The main goal of the surgery is to restore stability to the injured knee.

Deciding to Have ACL Surgery

Whether or not a doctor recommends surgery to repair a torn ACL depends on many factors, such as:

  • Age. While there is no age cut-off for surgical intervention, it is rarely performed on individuals over age 55.
  • Activity level. Surgical reconstruction may also benefit young people and those who participate in occupations or sports that involve jumping, pivoting, cutting, or rapid deceleration.
  • Associated injuries. Patients with multiple knee injuries (ACL plus meniscus, fracture, or medial collateral ligament) generally benefit from surgery to prevent significant activity restrictions and minimize the risk of developing knee osteoarthritis.

An ACL tear increases the risk of developing knee osteoarthritis. Some people opt to have surgery hoping to reduce this risk. However, the effect of surgery on the development of knee osteoarthritis remains unclear.

See Knee Osteoarthritis Causes on Arthritis-health

A conversation about post-surgical expectations as well as long-term risks, such as arthritis, should occur before undergoing ACL reconstruction. Ultimately, it is up to the patient whether or not to have surgery.

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ACL Reconstruction

ACL surgery typically involves reconstructing the ligament using a graft. Reconstruction is often recommended because most injured ACLs cannot be stitched back together (repaired) due to the surrounding environment. Recent efforts have been made to find a way to improve this environment in order to repair the ACL without using a graft. The graft may be from:

  • The person’s own body (autograft)
  • A donor (allograft)

Researchers have experimented with synthetic grafts, but so far these have proven inferior to natural grafts.

Below are the most common tissues used for ACL grafts. The graft material acts as a scaffolding for new ligament tissue to grow on. Each type of graft material offers unique benefits.

  • Patellar tendon. A patellar tendon autograft utilizes the patient’s own tendon to replace the torn ACL. The patellar tendon is known to heal quickly, which makes it a popular choice for a graft.
  • Hamstring tendon. Autografts using the patient’s hamstring have become increasingly more common. They have shown decreased post-operative knee pain and easier surgical recovery compared to patellar tendon grafts.
  • Quadriceps tendon. Quadriceps autografts are often used on people who have previously had ACL reconstruction.
  • Cadaver tendon. Allografts, which are the utilization of cadaver tendons, are preferred by some surgeons because they do not require removal of the patient’s own tendon.

No specific graft type has proven to be superior aside from that with which a particular surgeon is most experienced.

ACL reconstruction is typically done using a minimally invasive, arthroscopic approach. Special surgical tools and a video camera are inserted through small incisions in the knee joint. The surgeon will secure the graft to the tibia (shin bone) and femur (thighbone) using sutures (special surgical thread).

See Guide to Knee Joint Anatomy

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ACL Surgery Recovery

Generally, ACL surgery does not require an overnight stay in the hospital. Most people can move the knee immediately following surgery. Within a few days, post-operative rehabilitation may begin. Rehabilitation is essential to:

  • Maximizing long-term outcomes
  • Improving range of motion
  • Increasing strength
  • Restoring balance and proprioception

See Advanced Exercises to Restore Proprioception

Formal physical therapy is often recommended after surgery. Some surgeons recommend the use of knee braces; however, there is no evidence demonstrating improved outcomes with their use.

Some research indicates that it may take more than 6 months to regain symmetrical knee functionality. In general, an athlete can return to his or her sport between 9 and 12 months following surgery. The orthopedic surgeon will determine when it is safe to return to athletic activities.

Dr. Michael Khadavi is a sports medicine physician specializing in spine care, musculoskeletal ultrasound, regenerative medicine, and sports-related injuries. He practices at Kansas City Orthopedic Alliance. Dr. Khadavi is an educator in regenerative medicine and has been an invited lecturer at the American Academy of Physical Medicine and Rehabilitation, Association of Academic Physiatrists, Major League Soccer, and Stanford University.

Dr. Michael Fredericson is a sports medicine physiatrist with more than 25 years of experience. He serves as a Professor and the Director of Physical Medicine and Rehabilitation Sports Medicine at Stanford University School of Medicine.

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