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What is the difference between ACL injury and PCL injury?
A cruciate ligament rupture is when one of the two ligaments in your knee is torn. It can happen to either the anterior cruciate ligament (ACL) or the posterior cruciate ligament (PCL). Both ligaments are essential for the stability of the joint. While an ACL injury is more common and is usually caused by sport and exercise, a PCL injury is more likely to be caused by accidents. In rare cases, both ligaments can be torn.
“Cruciate ligament rupture” is the medical term for the complete severance of one of the knee ligaments. If the ligament is not entirely severed, it is known as a partial rupture. A PCL or an ACL rupture require immediate diagnosis and appropriate treatment so as to prevent long-term effects and prevent re-injury. With the right treatment you can make a quick recovery and soon return to your normal activities.
How does a cruciate ligament rupture happen? Causes and risk factors for ACL and PCL injury
A cruciate ligament can rupture if you twist your knee when exercising or if you have an everyday accident. Risk factors include weak muscles. An ACL or a PCL injury are often caused by the following activities:
Sporting accidents:
You are most likely to tear your ACL ligament due to quick changes in direction, jumps and decelerations – such as when playing football, hockey, basketball or when skiing or snowboarding.
Everyday accidents:
A PCL injury is more likely to be caused by an external force against the lower leg or, less commonly, by hyperextending the knee joint. This can cause the weight of the lower leg to shift backwards relative to the thigh. Car accidents and contact sports often lead to PCL injuries.
In general, men are more likely to sustain an ACL injury than women. A torn ACL or PCL often occurs in conjunction with other injuries such as trauma to the collateral ligaments, the meniscus or joint cartilage.
Ligaments do not always tear or rupture, they can also be sprained. The symptoms and treatment of a sprained ligament can be similar to those of a ruptured ligament. All cruciate ligament injuries require immediate medical attention in order to be diagnosed and treated quickly and correctly.
How to prevent a cruciate ligament injury?
A good way to prevent torn ligaments is to build up sufficient muscles to support your knee. Other preventative measures include:
- Tailoring your exercise routine
- Using good-quality equipment
- Specific coordination training
Signs and symptoms of an anterior cruciate ligament and a posterior cruciate ligament injury
Symptoms can vary depending on the type and severity of the injury. The main symptoms of a torn ACL or PCL are pain, swelling of the knee, instability and the feeling that your knee is about to give way. Particularly in the case of an ACL injury, you may hear an audible popping or tearing sound at the time of the injury. A PCL injury is usually inaudible. You will typically experience the following symptoms:
- Pain: a sudden stabbing pain in the knee usually happens when the injury occurs and may persist, especially when you move or put weight on the knee. If you experience a PCL injury, the pain will mainly be in the back of the knee.
- Swelling and bruising: your knee will usually swell up within a few hours of the injury. It will often be severe and may restrict movement in the joint. Bruising may be limited to the back of the knee with a PCL injury.
- Instability: after a cruciate ligament injury, your knee may be unstable. It might give way or – in the case of a PCL injury – feel like it’s “slipping”, especially when you put weight on it.
- Discomfort when walking or running: patients often report a feeling of instability in their knee, as if it’s about to give way. A torn ligament can make it difficult to extend or flex the knee. If you experience a PCL injury, you may have difficulty stretching the knee and feel that the joint is unstable, especially when going down stairs or slopes.
Different symptoms for anterior and posterior cruciate ligament ruptures
Anterior cruciate ligament rupture
- Pain and severe swelling in the knee area
- Feeling of instability under load
- Inhibition of extension and flexion in the knee joint
Posterior cruciate ligament rupture
- Pain and effusion, especially in the back of the knee
- Increased “slipping” of the knee joint when walking downhill
- Difficulty extending the knee joint
How is an ACL tear or a PCL injury diagnosed?
Diagnosing a cruciate ligament rupture requires a combination of medical tests and imaging techniques to confirm the injury and determine its severity. The most common methods include:
Clinical examination
A clinical examination will identify swelling, impaired movement and pain, and will also verify the stability of the knee.
Drawer test
The drawer test is the first-line clinical assessment used to diagnose a cruciate ligament rupture, determine the need for further examinations and begin appropriate treatment.
During the test, the knee is positioned so that the ligament function can be assessed. The aim is to detect instability of the knee joint, which is often associated with a torn ACL or PCL. If the ligament has not ruptured, the knee should remain stable; however, if it has torn, the tibia will move forward more relative to the femur (in the case of an ACL injury) or backward (in the case of a PCL injury). The Lachman test is a type of drawer test with a 20° flexion and can determine whether an ACL injury is present. If there is excessive forward or backward movement of the tibia, the drawer test is considered positive. The test is performed by a doctor.
Pivot shift test
If an ACL injury is present, the pivot shift test – a clinical examination to check the functionality of the anterior cruciate ligament – will also be positive.
Magnetic resonance imaging (MRI)
An MRI scan can provide detailed images of the knee joint. It gives an accurate picture of the ligaments, both anterior and posterior. MRIs can show whether the ACL or the PCL is partially or completely ruptured; it can also determine the severity of the tear and diagnose any associated injuries.
X-rays
Although X-rays do not actually show the torn ligament, medical professionals often use them to see if there are any associated bone injuries.
By combining various examination techniques, your doctor can make a precise diagnosis and assess the severity of the injury. This is crucial for the choosing the right treatment options, which can be either conservative with physiotherapy and rehabilitation, or operative with ligament reconstruction surgery.
Quick overview: differences in the diagnosis of anterior and posterior cruciate ligament ruptures
Anterior cruciate ligament rupture
- Snapping or tearing rupture noise
- Positive pivot shift test or anterior drawer test
Posterior cruciate ligament rupture
- Usually inaudible when tearing
- Folding of the lower leg backwards after rupture
- Positive posterior drawer test
Therapy and treatment for a torn cruciate ligament
RICE is a proven method for immediate treatment and first aid for many injuries including torn ligaments. It stands for:
Rest: immediately stop doing the activity that caused the ligament injury. Keep the knee still, avoid all movement and do not put weight on it.
Ice: placing a cold compress on the injury can help reduce pain and swelling. Wrap the compress in a towel and apply it to the injured knee. Make sure the coldness does not come into direct contact with the skin to prevent ice burn. Ice the knee for around 20 minutes at a time at regular intervals.
Compression: wrapping an elasticated bandage around the injured knee along with icing it can also help alleviate swelling and bruising. The bandage should be snug, but do not wrap it so tightly that it cuts off the blood circulation.
Elevation: after applying ice to your knee, elevate it on a cushion or any other kind of increase. This will increase return flow and can also help minimise swelling.
Further treatment will take your age, level of activity and severity of the injury into consideration.
Conservative treatment for a torn ligament
A PCL injury is more likely to be treated conservatively than an ACL injury. Conservative treatment in the form of physiotherapy and a knee brace (orthosis) may also be considered for injuries such as partial ruptures and/or if your general physical stress is low. The aim is to strengthen the surrounding muscle, restore mobility to the knee and improve stability. Physiotherapy can also help alleviate pain and accelerate recovery.
Wearing a medical device, such as a PTS knee brace, can improve stability during recuperation and protect against putting too much weight on the leg.
If you have a PCL injury and the drawer test is still positive after several weeks of conservative treatment, your doctor may recommend an operation.
Operative treatment for a torn ligament
Surgery is performed after the swelling has subsided. After the operation, you will immediately start load bearing if you have an ACL injury; however, this is a more gradual process in the case of a PCL injury.
Ligament surgery involves replacing the torn ligament with a piece of your own tissue, such as a piece of your patellar tendon or a graft, to restore stability to the knee. This surgical procedure is usually carried out using keyhole surgery (arthroscopy) and requires careful follow-up treatment and rehabilitation.
You will work with your doctor to decide which treatment is right for you. Without proper treatment, a torn ACL or a PCL injury can lead to long-term complications such as knee instability and cartilage damage. Therefore, it is important to follow you doctor’s advice to ensure the best possible outcome.
The most important differences in the treatment of anterior and posterior cruciate ligament ruptures at a glance:
Anterior cruciate ligament rupture
- The most common therapy is surgery with a cruciate ligament replacement
- Conservative therapy if general physical stress is low
- Rapid transition to the weight-bearing phase and increased load
Posterior cruciate ligament rupture
- Often conservative therapy
- Stabilisation and immobilisation with orthosis (PTS splint for posterior tibial support)
- Surgery if conservative therapy over several weeks does not have the desired effect
- Slow increase in mobility and weight bearing
Exercises as part of treatment for a PCL injury
Proper post-surgery care and specific exercises are crucial for strengthening the muscles, restoring mobility and stabilising the knee. Follow your doctor’s or physiotherapist’s instructions to ensure a successful recovery.
Returning to full activity after a cruciate ligament rupture
You, your doctor and your physiotherapist will decide together when you can get back to sport. The decision will be based on clinical examinations, physiotherapeutic progress and your own personal aims. Depending on the injury, the patient, the type of treatment (conservative vs. operative) and the healing process, returning to full activity can take between six months and one year.
Can a cruciate ligament repair itself?
The PCL is more likely to repair itself than the ACL. Thanks to new treatment concepts, conservative treatment can heal the injury with the right positioning. Targeted therapy is necessary in all cases to restore functionality and stability to the knee.
Which doctors treat an ACL or a PCL injury?
Orthopaedic and trauma clinics are the right places to go to if you have either an cruciate ligament ACL injury or a PCL injury as they are specialised in diagnosing and treating knee injuries.
medi products for cruciate ligament injuries
medi offers a range of products that can help you recover from a knee injury. These include knee bandages, knee braces and special compression stockings, all of which help to speed up recovery, reduce swelling and improve stability in the knee.
Anterior cruciate ligament rupture
Posterior cruciate ligament rupture
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