The modern state of ACL repair and how ACL tear treatment has progressed

Anterior cruciate ligament (ACL) tears are one of the most common knee injuries for athletes and non-athletes alike. With decades of concentrated research and medical advancements, are ACL tears still the career-haunting injury they have a reputation for?

We spoke with Christopher Kaeding, MD, executive director of Sports Medicine at The Ohio State University Wexner Medical Center, to explain how ACL tears rehabilitation and treatment has evolved.

Dr. Kaeding is also an orthopedic specialist and surgeon at the Jameson Crane Sports Medicine Institute, the lead orthopedic physician for the Ohio State Buckeyes football team and the Judson Wilson Professor in the Department of Orthopaedics at The Ohio State University College of Medicine.

Why do ACLs tear?

The anterior cruciate ligament is one of the ligaments that connects your thigh bone to your shin bone at the knee. While modern medicine doesn’t yet have a full understanding of why ACLs tear, extensive research has determined the biggest risk factors and movements that lead to this type of injury, Dr. Kaeding says.

“Most commonly, ACL injuries occur in competitive sports that involve what we call a 'cutting' motion — abrupt slowing and changing of direction,” he says.

In the United States, the vast majority of ACL tears occur in soccer, football, basketball, rugby and lacrosse.

More than 60% of ACL injuries are non-contact, meaning another player or object did not strike the knee. The actions that can put your ACL at risk are actually common athletic motions such as...

• Pivoting with one foot planted
• Stopping suddenly
• Landing awkwardly (hips and/or knees unaligned)
• Slowing down and changing direction (cutting)

“These motions have the potential to put substantial tension on the ACL and contribute to a partial or full tear.”

Are PCL tears common?

The posterior cruciate ligament (PCL) runs across the ACL in the center of the knee, forming an X inside of the knee, hence the name “cruciate.”

“PCL tears are a less common injury, especially compared to ACL tears,” Dr. Kaeding says. “The ACL is thinner than the PCL, drastically raising the chance of injury.”

Why are ACL injuries more severe than other ligament tears?

The vast majority of ACL tears are “complete,” meaning that the function of the ligament has been entirely lost.

“Athletes tear ligaments all the time,” Dr. Kaeding says. “However, unlike an ankle sprain, where you can tear a ligament and have a full recovery with rest and appropriate care, a complete ACL tear has very limited ability to heal itself on its own.

“Based on what we know about these ligaments today, we believe this is due to the ligament being bathed in joint fluid, which impairs healing.”

What is a torn ACL recovery process like?

These days, a full reconstruction of the ACL (building a new ligament with new tissue) is far more common than a repair (reattachment of existing tissue). In the past decade, newer techniques have been explored to “repair” the torn ACL, but reconstruction is still the gold standard of treatment.

“The goal of ACL reconstruction is to stabilize the knee,” Dr. Kaeding says. “After a tear, surgeons will likely use a tissue graft to replace the torn ligament and have the graft biologically incorporated into the knee. Following surgery, the recipient can expect a multi-month recovery and rehabilitation timeline. However, the ‘full recovery’ date is dependent on the individual and their goals.”

Several studies show that it typically takes two years for the bone and graft in a reconstructed knee to be 100% recovered.

“However, athletes who are committed to rehabilitation can typically get back to playing in around nine months,” Dr. Kaeding says. ”For non-athletes recovering from ACL surgery, the recovery timeline for activities of daily living is much quicker than for the recovery goal of higher-level athletes. You can be off crutches and driving within a few weeks and doing non-cutting exercise within two to three months.”

How has ACL injury treatment changed over the past 30 years?

Over the past 30 years, treatment plans, outcomes and perception around ACL reconstruction have changed drastically.

“Prior to the early ‘90s, recovery and rehabilitation plans following ACL surgery were almost entirely the reverse of today’s approach,” Dr. Kaeding says. “In the past, doctors attempted to approach ACL recovery by immobilizing and/or limiting motion. Today, we have both advanced surgical techniques and the knowledge that an early reintroduction to movement following surgery leads to drastically improved patient outcomes.

“Reports show that over 90% of athletes experience a successful restoration of stability and return to full usage of their knee after ACL reconstruction surgery.”

While vast improvements in rehabilitation and surgical techniques have led to more successful long-term results for those recovering from ACL tears today, not all athletes have returned to their sport, Dr. Kaeding notes.

For athletes without the incentive of a college scholarship or payment from a professional league, return to higher-level sport becomes less desirable when considering the risk of a re-tear and enduring another lengthy recovery. This fear of re-injury is known as kinesiophobia.

For others, a change in their life situation, such as graduating from high school and no longer participating in organized sports, affects their reported return to sport after surgery.

“Public perception of the knee’s ability to return to full function after an ACL injury has also changed drastically,” he points out. “Even during the early ‘90s, history of an ACL tear could disqualify you from military service due to the assumption that the knee couldn’t hold up over time. By the turn of the millennium, recruits were able to join as long as they could prove to have completed a sufficient recovery.”

Are ACL injuries as common as they used to be?

Full prevention of an ACL tear remains impossible, especially in sports that feature lots of sharp cutting motions, Dr. Kaeding says.

“However, present-day ACL reconstruction and rehabilitation techniques are allowing individuals to return to daily life more quickly and safely than previously thought possible, as well as sustaining the careers of athletes. What used to be a 12-month minimum recovery for an athlete’s return to sport is now five to six months in some cases. While this depends on several factors such as personal incentives and medical support, it demonstrates the significant advancements in ACL care.

“Advancements in neuromuscular training also offer preventive measures to improve the strength of athletes’ knees. Prevention training is a modern development with growing popularity, due to its demonstrated effectiveness in reducing the chance of an ACL injury.”