The anterior and posterior cruciate ligaments allow for flexion and extension of the knee. Tears of these ligaments are a common result of sudden movements that cause strain. Injury can occur from sudden stops or from trauma to the knee as a result of sports activities. When the tear is severe, surgery is often needed. Rehabilitation and exercises to retain mobility of the joint and to preserver strength prior to surgery. After surgery, the recovery process follows a distinctive set of steps.

Anterior Cruciate Ligament Tears and Repairs

Introduction

Tears of the anterior and posterior cruciate ligaments are a common knee injury that affect people of all ages and activity levels. The injury can range from minor to severe, depending on the extent of the tearing. Some, but not all require surgery to restore range of motion to affected joint. The injury often requires extensive rehabilitation to regain function. The following explore the cycle of this injury further.

Physiology of the Injury

The knee consists of the intersection of three bones, the femur, tibia, and patella. The patella sits in front of the joint to provide protection to the soft tissues. Ligaments connect these bones and keep the knee stable. The cruciate ligaments are located on the inside of the knee joint. They form an X with the anterior cruciate ligament in the front and the posterior cruciate ligament in the back. These ligaments allow for the extension and flexion of the knee (OrthoInfo, 2019). A tear to these ligaments disrupts the ability to move the knee and can affect the ability to walk.

An injury to these ligaments can have an effect on the normal homeostasis of the body by reducing the ability to move the knee in the full range of motion and can interfere with stability when standing and with mobility (OrthoInfo, 2019). The injury will also activate the inflammatory and potentially the immune response. The injury can also have an impact on the body if the pain causes the person to lose sleep or be unable to perform daily activities. Pain from the injury can be a source of stress and activate the cortisol response. In addition, compensating for the injury can cause strain or damage to other joints in the body. The injury can have an impact on the overall health of the person and affect the body beyond the ability to move the knee.

The impact of the injury on the body depends on the grade of the injury. They are classified into Grade 1 sprains, which are mildly damaged ligaments that have been slightly stretched. Grade 2 sprains are where the ligament has been stretched to the point where it becomes loose and may have a partial tear (OrthoInfo, 2019). A Grade 3 sprain is where a complete tear of the ligament has occurred (OrthoInfo, 2019). The knee is unstable with a grade 3 strain and will typically require surgery to repair.

Etiology

The most common cause of a cruciate ligament tear is changing direction rapidly or stopping suddenly. It can also be caused by suddenly slowing down while running or landing incorrectly while jumping (OrthoInfo, 2019). One of the most common causes of a cruciate ligament tear is from impact due to contact sports such as football, soccer, or baseball (OrthoInfo, 2019). Improper alignment of the joint when bearing weight can cause a ligament strain or tear.

Female athletes have a tendency to experience ACL tears more frequently than males. It has been proposed that this is due to different in muscular strength and neuromuscular control (OrthoInfo, 2019). It has also been suggested that estrogen creates increased looseness in the ligaments, which increases the risk for injury (OrthoInfo, 2019). Regardless of age, physical conditioning and attention to proper alignment when performing any type of task will help to prevent damage to the knee joints and tissues.

Signs and Symptoms

When a cruciate ligament tear occurs, the symptoms are sudden and noticeable. The person may hear a pop and the knee may give out. There will also be pain and swelling at the injury site. The swelling will increase over the next 24 hours. The person typically loses range of motion and there is tenderness in the joint. The person may experience pain while walking, or when moving from sitting to standing. The pain and swelling may resolve in 24 hours, but returning to full activity runs the risk of further injury, possible damaging the meniscus (OrthoInfo, 2019).

Diagnosis of the injury includes a physical examination of the structures of the injured knee and imaging tests which may include an MRI. X-rays will sometimes be performed to determine if there has been damage to the surrounding bone (OrthoInfo, 2019). This is especially the case if the injury occurred in connection to a fall or impact. An MRI can help visualize the soft tissues, such as the cruciate ligament and is more useful for diagnostic purposes than an X-ray, in most cases.

Treatment and Return to Function

Several factors affect the speed of healing the return to full function. The first is the level of physical activity that is desired. The time it takes to heal also depends on the extent of the injury and whether there are any other injuries accompanying the ACL tear. The person’s overall physical health and age can also affect the recovery time.

The first six weeks after the injury are generally the same for all levels of injury. During this time, it is generally recommended that the person avoids full weight bearing, and the knee should be protected or immobilized (Massachusetts General Hospital, 2019). The first phase of the recovery process requires giving the knee protection, rest, and time to heal. Placing a pillow under the knee for comfort should be avoided, as this can lead to the knee becoming stiff (Massachusetts General Hospital, 2019). The pain and swelling typically subside in about three weeks and the person can then begin gentle motion to regain range of motion. A stationary cycle or swimming using the flutter kick and typically recommended as early stage recovery exercises (Massachusetts General Hospital, 2019).

An ACL tear is a complicated injury that significantly affects the stability and mobility of the knee joint. They often take significant time to heal and involve extensive rehabilitation, even for minor tears (Quinn, 2018). The most important goal of the early healing process to avoid compression through weight bearing and to retain as much strength as possible (Quinn, 2018). Exercising must be done in such a way as to avoid further injury to the joint. Even if surgery is needed to repair the tear, exercises are typically recommended to retain strength and to provide the best opportunity for optimal outcomes after the surgical procedure (Quinn, 2018). The exercises in the early stages of recovery focus on strengthening the muscles surrounding the knee, without compressing the knee (Quinn, 2018).

At the recommendation of the physician or a physical therapist, many of these exercises can be done at home or at a facility. The most important thing to avoid is further injury, which can significantly lengthen recovery time. The old saying of “no pain no gain” is not always applicable to the early stages of the healing process (Quinn, 2018). Pushing too hard, too fast can lengthen the time that it takes to heal. It is typically recommended that one waits until the swelling subsides before beginning exercises (Quinn, 2018). Healing from an ACL injury takes place in stages.

Stages of Recovery and Rehabilitation Exercises

Early Stages

In the early stages of the recovery phase, the emphasis is on rest. Exercises are typically not recommended until the swelling subsides, which is typically around three weeks for a moderate to severe strain (Quinn, 2018). When this phase has passed and it is time to begin exercising, the knee is still fragile and there is a greater risk of injury. It is recommended that early exercises go slow and it is typically best if they are performed under supervision. The following are some exercises that can be performed after the initial healing phase of the injury.

1. Heel Slides. Sit on the floor with the knees outstretched. Slowly bend the knee as you slide your heel across the floor toward you. Return the foot to the starting position slowly (Quinn, 2018).

2. Isometric Quad Contractions. Sit on the floor with the injured leg extended and the opposite leg ben. Slowly contract the quadriceps of the injured knee without moving the leg. Hold for 10 second and then slowly relax (Quinn, 2018).

3. Prone Knee Flexion. Lie on the stomach with the legs straight. Flex the injured knee and bring the heel towards the buttocks. Hold for 5 seconds and then slowly relax (Quinn, 2018).

It is recommended that these exercises be repeated 10 times, if possible. It is important to realize that in the beginning, you might not be able to do the entire 10 repetitions. One of the most important factors is that one does not push to the point of reinjury.

The first milestone in the recovery process is when the swelling in the knee subsides and the person has the ability to be able to stand squarely with both feet flat on the floor without favoring the uninjured leg. Once this point has been reached, additional exercises can be added to the regime (Quinn, 2018). However, it is important not to progress to the next phase until this milestone has been reached. One the ability to bear equal weight on both knees has been reached, the following can be added.

1. Passive knee extensions. Place two chairs of equal height facing each other with the seats facing each other. Sit on one chair and place the heel of the injured leg on the other. relax and allow the knee to softly straighten. Reset in this position for one or two minutes (Quinn, 2018).

2. Heel raises. Stand with one hand on the back of a chair for balance. Slowly raise up to stand on the tiptoes. Hold for 5-10 seconds (Quinn, 2018).

3. Half Squats. Hold a sturdy table with both hands. Slowly bend the knees until the hips are in a half squat. Hold of 10 second, then slowly return to a full standing position (Quinn, 2018).

4. Stand on one leg. Using the back of a chair or a table for support, stand on the injured leg for 10 seconds. This may take a few weeks to work up to, even with a mild form of the injury (Quinn, 2018).

These exercises represent examples of exercises that can be done in the early stages of the injury. The second set should not be added until the exercises in the first set are easy to perform and become easy. It is important not to become too anxious and progress too quickly. The injury needs time to heal as it continues to strengthen and rehabilitate. These exercises can be done regardless of whether the injury needs to be repaired with surgery or not. They focus on the tissues surround the knee rather than the cruciate ligaments themselves. If the injury does not require surgery, exercises may be added as the cruciate ligaments regains strength.

Presurgery Protocol with Rehab Exercises

After a cruciate ligament tear, there is a danger that leg strength, motion, and knee stability will be lost. It is important to regain strength as quickly as possible to aid return to full functionality. The protocols prior to surgery are similar to those, even when the healing process will involve rehab instead of surgery. The exercises mentioned early should still be used. However, the following are also recommended prior to surgery.

1. Straight leg raise to the front. Lie on your back with the injured leg straight and the uninjured leg bent. Point the toes straight up to the ceiling. Lift the heel off the floor, using the thigh muscles as the key group being used. Hold about 12 inches off the floor for about 5 second and then slowly lower the leg to the floor (Cigna, 2017).

2. Straight leg raise to the outside. Lie on your side with the injured leg on top. Keeping the leg straight, use the inner thigh muscles to raise the injured leg off the floor about 12 inches. Hold this for about 5 seconds, then slowly lower the leg to the floor (Cigna, 2017).

3. Hamstring Curls. Lie on your stomach with your knees straight. Life the foot of the injured leg so that the heel moves towards the buttocks. If this causes pain, it should be avoided until it can be done comfortably (Cigna, 2017). Ankle weights can be added once curls without the weights become easier (Cigna, 2017).

There are other exercises that can be added, but this set of exercises works the major muscle groups and is relatively safe with various degrees of injury. These exercises are recommended prior to surgery, but they are also used as the next phase of rehab, if physical therapy will be used without surgery.

Type of Surgery

ACL repair involves using a graft to replace the torn ligament. Graphs are typically from the person’s own body. The most common tendons used are the patellar tendon or one of the hamstring tendons (Healthlink BC, 2015). Sometimes the graft is taken from a deceased donor (Healthlink BC, 2015). In some cases, a piece of the bone is also separated and must be reattached during surgery (Healthlink BC, 2015). In most cases, the surgery can be done arteroscopically with only a few small incisions (Healthlink BC, 2015).

Post-surgery Protocols with Rehab Exercises

Many persons who undergo surgery for repair of the cruciate ligament are under the misconception that because it is usually possible to go home the same day as surgery, that the recovery process will be easy and fast (UMPC Orthopaedic Care, 2015). However, regardless of how long one must stay in the hospital, the recovery process to full functionality is a long process. Full recovery can take between 2 to 9 months post-surgery (UMPC Orthopaedic Care, 2015).

In the first two weeks after surgery, no weight bearing will be allowed. Crutches are typically required for the first four weeks after surgery (UMPC Orthopaedic Care, 2015). Sometimes, a passive motion machine is used that provides movement without relying on the knee muscles. Resting and caring for the incision site is a priority in the first few weeks (UMPC Orthopaedic Care, 2015).

In 2-4 weeks weight bearing will begin and physical therapy is typically 2-3 times per week. In weeks 2-9, the difficulty of the physical therapy increases with the goal of returning to regular physical activity (UMPC Orthopaedic Care, 2015). The individual goals of the patient will determine the intensity and length of the physical therapy after surgery (UMPC Orthopaedic Care, 2015).

Conclusion

A tear of the anterior and/or posterior cruciate ligament is a common injury caused by overexertion or trauma to the knee. The length of recovery time and whether it requires surgery depends on the grade of the injury. This injury requires a long healing process, even for minor injuries. If surgery is needed, a graft is taken from another portion of the body, in most cases. The rehabilitation process focuses on regaining strength, while avoiding reinjury. Full recovery is a long process, depending on the degree of strength and activity level of the person.

References

Cigna. (2017). ACL Injury: Exercises to Do Before Treatment. Retrieved from https://www.cigna.com/individuals-families/health-wellness/hw/medical-topics/acl-injury-ug2544

Healthlink BC. (2018). Anterior Cruciate Ligament (ACL) Surgery. Retrieved from https://www.healthlinkbc.ca/health-topics/hw28289

Massachusetts General Hospital. (2019). Exercises After Injury to the Anterior Cruciate Ligament (ACL) of the Knee. Retrieved from https://www.massgeneral.org/ortho-sports-medicine/conditions-treatments/pdfs/Acute%20ACL%20injury%20rehab.pdf

OrthoInfo (2019). Anterior Cruciate Ligament (ACL) Injuries. Retrieved from https://orthoinfo.aaos.org/en/diseases–conditions/anterior-cruciate-ligament-acl-injuries/

Quinn, E. (2018). 8 Best Exercises to Help with ACL Rehabilitation. VeryWell Health. Retrieved from https://www.verywellhealth.com/acl-rehab-exercises-3119304

UMPC Orthopaedic Care. (2015). ACL Reconstruction Surgery: Before and After Recovery Timeline. Retrieved from https://share.upmc.com/2015/04/recovery-time-for-acl-reconstruction-surgery/