This was a question from a young dancer that I helped rehab several years ago. She had fallen out of a jump and sustained a partial PCL tear. Lucky for her, the PCL can heal on its own. The young dancer was back to her normal leaps and turns in about 6 weeks. She had a fairly easy rehab because the injury was just to the PCL, and it was a partial tear rather than a complete tear. To learn more about the PCL, read on. We will start with anatomy!
The knee joint
The knee is the largest joint in the body. It is made up primarily by the tibiofemoral joint and patellofemoral joint. The tibiofemoral joint is what most of us think of as the knee. It is the joint made between the bottom of the femur (the thigh bone) and the top of the tibia (the larger lower leg bone). The patellofemoral joint is the joint made between the femur and the patella (the kneecap).
What are ligaments?
Every joint has ligaments. Their function is to control excessive motion of the joint. They are also a source of proprioception. Proprioception is knowing where you are in space. For the knee, this means that you would be able to determine the position of the knee without having to look at it. Ligaments are primarily made of collagen fibers and have very little elasticity. They are meant to add stability and are not flexible. You cannot stretch a ligament without damaging it.
What is the PCL?
The posterior cruciate ligament or PCL is located inside the knee joint. The PCL runs from the end of the femur (the thigh bone) to the top of the tibia (the shin bone). Its primary function is to prevent the tibia from sliding backward on the the femur. It also assists in limiting hyper extension, side to side movements, and rotation of the tibia. The PCL is twice as thick and twice as strong at the ACL. Thus it is injured less often than the ACL.
What is a sprain? Is it different than a strain?
A sprain is a tear or injury to a ligament. Whereas a strain is a tear or injury to a muscle or tendon. When the PCL is injured, it is considered a sprain because the PCL is a ligament at the knee.
How does the PCL get injured?
There are two main ways that injury occurs to the PCL.
- Motor vehicle accidents
- This is the most common cause of PCL injuries. It accounts for 45% of all PCL injuries.
- The most prevalent PCL injury is called a dashboard injury. It occurs when the top of the tibia is pushed up against the car dashboard.
- Sports
- This is the second most common cause of PCL injuries. It makes up about 40% of all PCL injuries.
- In most cases the PCL is injured when falling forward on a bent knee. However, hyper extension with knee rotation, an awkward landing from a jump, or a rapid change in direction could also lead to PCL injury.
- These are more likely to be isolated injuries to the PCL and not involve other knee structures.
- The most common sports for PCL injuries include dancing, soccer, football, baseball, and skiing.
How bad is the tear?
As with all sprains, there are grades to the severity of the injury. These grades include:
- Grade 1: This is the mildest sprain. The ligament fibers are stretched but not torn. Walking will, most likely, not be affected. Some swelling and tenderness to the touch might occur but no instability.
- Grade 2: This is a partial tear of the PCL, but it is not a complete tear. There is more pain and swelling in the knee. There will be some feelings of knee instability.
- Grade 3: This is a complete tear. There will be swelling and pain in the knee. There will be significant knee instability. This type of tear often occurs concomitant with an anterior cruciate ligament (ACL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and/or meniscus injury.
What are the symptoms of a PCL tear?
There are many symptoms associated with a PCL tear. However these symptoms will be different depending on if the tear is isolated to the PCL or if other structures in the knee are damaged.
- Symptoms of isolated PCL tear
- Pain in the back of the knee
- Mild or moderate swelling
- Knee feels unstable
- May have difficulty going up and down steps or walking on an incline
- Pain with squatting
- Knee stiffness
- Pain when running or jumping
- Typically no “pop” is heard when a PCL is torn
- Symptoms of PCL tear with additional ligament damage
- Increased swelling
- Knee pain
- Feelings of instability
- Decreased ability to bend and straighten the knee
- Difficulty walking
Will I need surgery?
The answer is probably not, but maybe. Partial PCL tears have the ability to heal on their own. Therefore, Grade 1 and grade 2 sprains can recover with physical therapy. Return to play usually occurs in 4-6 weeks. A grade 3 tear can also recover without surgery in some cases. Return to play usually occurs in 3-4 months in the case of an isolated grade 3 PCL tear. Surgery is warranted if there is significant knee instability from a recent or even a chronic grade 3 tear. Also surgery could be required if there were other ligamentous injuries present.
Who should I see?
- Physical therapist – A physical therapist is going to be an integral part of the healing process. Whether or not the person decides to have surgery, they will need physical therapy. Physical therapists can aid in decreasing pain and swelling, increasing strength and flexibility, and returning to sport safely. It is important to have a physical therapist assist in determining when the person is appropriate to return to sport and provide direction in how to prevent the injury from reoccurring.
- Orthopedist – An orthopedist is needed to determine the extent of the injury in the knee. Imaging and special tests will help determine the injury status of the knee. The orthopedist would then discuss options including surgical reconstruction and/or physical therapy.
What can I do at home?
There are many things you can do at home to aid in your recovery. These include:
- Relative rest – It is important to prevent further injury to the knee while you are recovering. If you are having pain with walking or bearing weight on the affected leg, then use crutches to help. If you are able to bear full weight through the leg and have full knee motion, but are still unable to return to your sport, then practice relative rest. This means that you perform an alternate activity that will not affect the injury. For example, biking, walking, or swimming while you are unable to participate in your sport is an excellent way to maintain cardiovascular levels and strength. Having equal strength in both legs and no instability in the knee is required before returning to sport or activity.
- Ice – This is very important right after the injury. Ice the knee with an ice pack several times a day right after the injury especially if there is a lot of swelling. Elevate the knee above the level of the heart while icing to decrease the swelling. This can be done by lying on a couch and propping the leg up on a few pillows. Ice for about 20 minutes. Place a thin barrier, like a pillowcase, between your skin and the ice pack. You can continue to ice even after the initial injury especially if there is still pain and swelling.
- Range of motion exercises – These are very important to perform after the initial injury. They are very simple exercises designed to increase mobility of the knee while preventing the knee from getting overly stiff while recovering. They should be performed several times a day during the initial recovery. See the video below for some range of motion exercises for the knee.
- Flexibility exercises – These exercises are focused mainly on stretching the hip flexors, quadriceps, hamstrings, and the calf muscles. These muscles surround the knee and will tighten up when there is an injury to the knee. Improving the flexibility of these muscles will aid in the mobility of the knee. See the video below for instructions on how to stretch these muscles. You will need a stretch strap, dog leash, yoga strap, or something similar.
- Strengthening exercises – There are a couple different phases of strengthening when rehabbing from an PCL tear. These include weight bearing and non-weight bearing exercises. Weight bearing refers to putting weight through the joint. Examples of weight bearing include standing, running, walking – basically anything performed when standing on your feet. Non-weight bearing exercises are to be performed first to start strengthening the muscles with no impact through the knee joint. Also to note is that after an acute PCL injury, the knee is usually placed in an extension brace that keeps it straight. This allows the PCL to heal. The brace is usually on for 2 weeks for less severe tears and longer for complete tears.
- Once the extension brace is discontinued, normal knee motion is regained, and the person can walk/stand with little discomfort, then it is time to progress to weight bearing exercises. All of these exercises will focus on strengthening muscles around the knee and hip, especially the quadriceps. The quadriceps is the large muscle in the front of the thigh. When there is an injury to the knee it tends to shut down. This can lead to the feeling of the knee giving out. It is important to turn that muscle back on asap. Using resistance bands or ankle weights can add resistance and strength. See the video below for weight bearing and non-weight bearing exercises.
- Bracing
- A brace can provide support and increase stability when returning to previous sports or recreational activities.
- A knee sleeve can be helpful in decreasing pain and swelling when returning to activity.
In review
- The posterior cruciate ligament or PCL is located inside the knee joint.
- Its primary function is to prevent the tibia from sliding backward on the the femur.
- It also assists in limiting hyper extension, side to side movements, and rotation of the tibia.
- The PCL is twice as thick and twice as strong at the ACL.
- Thus it is injured less often than the ACL.
- There are two main ways that the PCL is injured.
- Motor vehicle accidents
- Sports
- There are grades of injury, with grade 1 being mild and grade 3 being a complete tear.
- PCL tears can be isolated or occur with other ligamentous injuries.
- Most tear are treated conservatively with physical therapy.
- Surgery would be needed if the person is unable to stabilize the knee after a grade 3 acute or chronic tear of the PCL.
- There are things that you can do at home:
- Relative rest
- Ice
- Range of motion exercises
- Stretching
- Strengthening
- Bracing
As always, If you have questions about the content of this post or any other musculoskeletal questions, please e-mail me.
Additional resources
https://www.physio-pedia.com/Posterior_Cruciate_Ligament_Injury
https://www.statpearls.com/ArticleLibrary/viewarticle/27494
https://www.choosept.com/guide/physical-therapy-guide-posterior-cruciate-ligament-injury
https://www.orthobullets.com/knee-and-sports/3009/pcl-injury