Treating a Torn ACL Knee in Children and Teens

Treating a Child with a Torn ACL: Knee Surgery and Rehab

The anterior cruciate ligament (ACL) is a ligament within the knee important for joint stability. In the past, surgeons may have hesitated to repair a torn ACL in children for fear of damaging the growth plates near the knee. They wanted to wait until after the bones stopped growing in the teen years.

Given the improved surgical techniques to treat ACL injuries in young people, that's no longer true. Research shows that it's better to fix the ACL rather than wait, and that waiting itself may cause further damage to the growth plates. Surgery is likely to be the best option in many cases.

This article explains the types of available ACL surgery for children and teens, and why it may be recommended. It also looks at strategies that can help your child heal after ACL surgery.

Teen girl playing soccer
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ACL Treatment Options

The knee joint connects the long bone in your thigh, called the femur, with the shorter shin bone of the lower leg, called the tibia. The ACL connects the two and is one of four ligaments that keep the knee working properly. It also is the one that's most often injured.

People who have torn the ACL will often hear a "pop" at the knee, and have pain or swelling at the injury site. An ACL injury can range from a relatively mild sprain to a complete tear that makes the knee unstable.

The severity of an ACL injury is determined by a physical exam, which may include several tests used to evaluate stability and motion. A healthcare provider also will look at X-ray and MRI images to better understand the degree of ACL damage. Treatment will depend on how serious the injury is.

Until the bones in teens and children stop growing, they are considered skeletally immature. The bone tissue at the physes, or growth plates, on the ends of the femur and tibia bones where the knee joint forms, may not be fully formed. For this reason, surgeons were hesitant to perform ACL repair in young people in the past. That's no longer the case. Research has shown that surgery is the better option in most cases, and there are newer techniques to protect the still-growing tissue.

Surgery

One of the key criteria for deciding whether or not surgery is needed is the extent of the tear. A system for grading ACL injuries ranges from Grade 1 (a minor sprain) to Grade 3 (a full ACL tear). A partial Grade 2 ACL tear is rare, but in some cases surgery may be the best course of action. If your child has a Grade 3 tear, then surgery is almost always needed to repair the ACL and unstable knee.

Surgery for a full ACL tear tends to be the best option in people who:

  • Are young and active, as most teens and children are
  • Participate in sports that involve a lot of jumps, turns, and rapid speed or direction changes
  • Experience significant knee instability

Non-Surgical Treatments

Not everyone who has an ACL injury needs to have surgery. If your child has a minor sprain or a rare partial tear, alternatives may include basic first aid along the R-I-C-E model. This acronym means:

  • Rest: Avoid weight bearing on the injured knee.
  • Ice: Ice packs can help decrease pain and swelling.
  • Compression: Use an elastic bandage or compression wrap around your knee.
  • Elevate: Lie with your injured knee propped up.

These interventions may be all that's needed, or they can be the initial care given to your child before a healthcare provider is able to further treat the ACL injury. Wearing a brace at the joint can keep the knee stable while the ACL injury heals.

Physical therapy (PT) also may be used in place of surgery, but for more than one reason. It may be all that's needed for a relatively minor ACL injury. It also may be used in people who cannot have or do not want surgery, because of age, activity level, overall health, or other reasons.

In most cases, though, PT comes after ACL surgery. It's a significant commitment that typically lasts for weeks and months. If you are considering surgery for your child's ACL tear, be sure to discuss PT requirements with your healthcare provider too.

Types of Surgery

In both children and adults, ACL repairs are usually done as arthroscopic surgeries. This means that a surgeon makes a number of small incisions at the knee joint. A tiny camera used to see inside the knee is threaded through these openings, along with long, thin surgical instruments.

In most cases, the ACL repair is a minimally invasive procedure that can be done in a few hours on an outpatient basis. The surgeon also will drill small holes to replace the damaged ACL and reconnect the joint. The new tendon used in the surgery may be one of two types. They are:

  • Autograft surgery, which means that the tendon comes from your child's own body. It may be taken from the knee, the back of the thigh (hamstring) or front of the thigh (quadricep).
  • Allograft surgery, which means the new tendon comes from an organ donor

ACL Surgery Modification for Children

There is a potentially important difference in how ACL surgery is done in children and teens. It has to do with the angle of approach when a surgeon drills into the bones of the affected knee.

When surgeons are performing a transphyseal ACL reconstruction, which is considered safe in teens and children, they need to drill small holes in parts of the active growth plates. These are the bone tissue areas that need to be protected as much as possible in young people.

A surgeon may use what's known as the independent drilling technique in ACL surgery. That's because in adults, the alignment of the drilling may lead to better outcomes and more natural knee motion when recovery is complete. In children and teens, though, it may cause more damage to the growth plates because the angle of approach during the drilling causes more disruption to them.

Some researchers have instead suggested that the more standard transtibial technique, which uses drill angles that better protect the growth plates, may be safer in younger people who have ACL repair surgery. While more research is needed to better understand the difference in teens and children, it's important to talk with your surgeon about the techniques they plan to use.

Recap

Not all ACL injuries require surgery, but a full tear of the ACL almost always will. This is usually done on an outpatient basis. A surgeon will replace the damaged ACL with a tendon taken from your child's own body or a donor, often while using a slightly different technique that spares the still-growing bone tissue in teens and children. The ACL repair is followed by physical therapy to ensure the best possible outcome after surgery.

Post-Surgery Therapy

If you're deciding whether or not to have a child's ACL tear surgically repaired, you also will need to consider physical therapy. Children and teens, in particular, are eager to get back to sports and other activities. They may think surgery is the end of ACL repair, but it's not.

Most young people will need physical therapy to restore as much function as possible, but there are differences when compared with what adults need to achieve that. Strengthening the front thigh muscles, for example, may take longer in young people than it does in adults. And targets across time may vary widely when it comes to range of motion exercises and how long they continue.

Physical therapy guidelines developed at Children's Hospital of Philadelphia place an emphasis on both time and tasks when measuring recovery after ACL surgery. They begin with keeping the knee braced and pain managed in the first week, but call for increased activity levels and targets during a recovery that lasts for nine months. Many factors will be key to your child's success, but perhaps none is more important than family support.

Prognosis

The prognosis for teens and children who have ACL surgery is generally good. There is a possibility of reinjury after the procedure, but the risk of meniscus tears and cartilage injury because of an unrepaired injury in an unstable knee is likely higher.

Despite improvements in the techniques used in ACL surgery for children, a surgeon will still need to drill holes that may affect the growth plates in the affected knee joint. This could affect the growth plates, leading to slightly different leg lengths or angular deformity.

Such deformity could, in turn, lead to knock knees (genu valgus) and bow legs (genu varus). These conditions progressively worsen with further growth and could lead to increased risk of problems such as joint damage and arthritis.

Summary

Surgery is generally accepted as safe for teens and children who have a torn ACL that needs repair. It may not be necessary in all cases, but when it is, there is a good chance the knee function will be restored. The procedure is much the same as it is in adults, with some changes in how the surgery is done so that it protects the still-growing bones as much as possible.

The ACL repair isn't the end of the road, though, and in some ways is just the beginning. Your child's recovery will likely require physical therapy once the procedure is complete, and that may take the better part of a year, depending on PT recommendations. You'll want to talk this over with your child to make sure they understand the commitment before a full return to sports and other activities.

A Word From Verywell

When considering surgery for your child because of a torn ACL, it's important to remember that there are risks to the surgery because their bones are still growing. But there are risks that are perhaps more serious if you wait. Talk to your healthcare provider before making a decision.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Cimino F, Volk B, Setter D. Anterior cruciate ligament injury: Diagnosis, management, and preventionAmerican Family Physician. 2010; 82(8):917-922.

  3. Hagino T, Ochiai S, Senga S, et al. Meniscal tears associated with anterior cruciate ligament injury. Arch Orthop Trauma Surg. 2015;135(12):1701-1706. doi:10.1007/s00402-015-2309-4

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Additional Reading
  • American Orthopaedic Society for Sports Medicine (AOSSM) Annual Meeting, July 2009.