Cruciate ligament tears are among the most common sports injuries in Hong Kong. But what exactly causes a cruciate ligament tear? And what’s the difference between an anterior cruciate ligament (ACL) tear and a posterior cruciate ligament (PCL) tear?
In this guide, OneEssential explains everything you need to know about cruciate ligament injuries — from their causes to treatment options.
What Is the Cruciate Ligament?
The cruciate ligaments are key stabilizing structures located in the center of the knee joint. They consist of two main parts — the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) — which cross each other in an “X” shape, hence the name “cruciate.”
These ligaments connect the femur (thigh bone) to the tibia (shin bone) and prevent excessive forward or backward movement of the tibia. Together, they maintain knee stability during activities such as running, jumping, and sudden changes in direction.
Anterior Cruciate Ligament (ACL)
The ACL lies in the center of the knee and prevents the tibia from moving too far forward. It plays a crucial role in maintaining stability during rapid direction changes, landings, or sudden stops.
Because of the high forces involved, ACL tears are one of the most frequent sports injuries, especially in activities such as football, basketball, skiing, and running.
Posterior Cruciate Ligament (PCL)
The PCL, also located in the center of the knee, prevents the tibia from moving too far backward. It helps stabilize the joint during actions such as squatting or walking downstairs.
Compared to ACL injuries, PCL tears are less common and usually result from trauma, such as car accidents, falls, or direct impact to the knee.
Causes of Cruciate Ligament Tear
1. Anterior Cruciate Ligament (ACL) Tear
The ACL is the most frequently injured ligament in the knee, accounting for 70–80% of all cruciate ligament tears. Common causes include:
- Sudden twisting or rapid change in direction
- Poor landing mechanics during jumps
- Direct collision or impact
- Overuse during high-intensity sports
As a result, ACL tears often occur during sports such as basketball, football, and other activities involving quick movement and jumping.
2. Posterior Cruciate Ligament (PCL) Tear
PCL injuries are less frequent and typically occur only under strong external forces, such as:
- Traffic accidents
- Falls with direct knee impact
- Heavy compression or blunt trauma to the front of the knee
Symptoms of Cruciate Ligament Tear
1. Symptoms of ACL Tear
- A “popping” sound at the time of injury
- Immediate and severe pain
- Knee swelling
- Bruising or internal bleeding in the knee joint
- Limited range of motion
- Knee weakness or instability, especially when bending
2. Symptoms of PCL Tear
- Dull or aching pain in the knee
- Backward movement of the knee joint (posterior instability)
- Difficulty squatting, climbing stairs, or walking downhill
- Knee swelling and stiffness
| Category | Anterior Cruciate Ligament (ACL) Tear | Posterior Cruciate Ligament (PCL) Tear |
|---|---|---|
| Cause of Injury | Sudden twisting or turning, abrupt stopping, or poor landing posture during jumps and collisions. | Traffic accidents, direct knee impact, or compression injuries from falls or blunt force. |
| “Pop” Sound at Injury | Common — many patients report hearing a distinct “pop” sound at the time of rupture. | Rare — sound is often faint or not noticeable. |
| Swelling | Rapid and severe swelling within a few hours due to joint bleeding (hemarthrosis). | Mild swelling that develops gradually over several hours or days. |
| Pain Location | Deep pain within the knee joint, often accompanied by surrounding tenderness. | Deep knee pain, often felt at the back of the knee with dull or diffuse discomfort. |
| Joint Stability | Obvious instability — patients may feel their knee “give way” or unable to support weight, especially when walking or changing direction. | Feeling of looseness or unsteadiness when walking downhill or descending stairs. |
| Impact on Daily Life | Significantly affects walking, running, and sports performance. | May cause minimal symptoms initially but can lead to gait changes, instability, and early joint degeneration over time. |
Cruciate Ligament Injury Grades
| Injury Grade | Characteristics | Common Symptoms | Impact | Treatment Approach | Estimated Recovery Time |
|---|---|---|---|---|---|
| Grade 1 (Mild Sprain) | Mild stretching of the ligament fibers without visible tearing. | Mild pain, slight swelling, minor discomfort during movement but still able to walk. | Knee joint remains largely stable. | Rest, ice therapy, physiotherapy, and muscle strengthening exercises. | 2–4 weeks |
| Grade 2 (Partial Tear) | Partial tearing of the ligament. | Moderate pain, swelling, limited movement; occasional feeling of knee looseness. | Decreased stability, difficulty performing sports. | Strengthening and stabilization training; may require bracing or, in severe cases, surgical consideration. | 6–12 weeks |
| Grade 3 (Complete Tear) | Complete rupture of the ligament. | Audible “pop” sound at injury, sharp pain, rapid swelling, significant instability and weakness when bending the knee. | Knee joint becomes highly unstable; unable to participate in sports, affecting daily walking. | Surgery is often required, followed by long-term physiotherapy and rehabilitation exercises. | 6–12 months |
Diagnosis of Cruciate Ligament Tears
Doctors or physiotherapists will perform clinical examinations such as the Lachman Test, Anterior Drawer Test, and Posterior Drawer Test to assess ligament stability and integrity.
In addition, an MRI (Magnetic Resonance Imaging) scan is often recommended to confirm whether the cruciate ligament is torn or damaged. MRI scans can also reveal associated injuries, such as meniscus tears or cartilage damage.
Treatment Options for Cruciate Ligament Tears
Treatment for cruciate ligament injuries is generally divided into conservative (non-surgical) and surgical approaches.
The choice of treatment depends on several factors, including which ligament is injured (ACL or PCL), the severity of the tear, the patient’s age, and activity level.
1. Physiotherapy
For acute injuries, physiotherapists will follow the RICE protocol —
Rest, Ice, Compression, and Elevation — to help reduce pain and swelling during the initial phase.
Once the acute symptoms have improved, the physiotherapist will design a personalized rehabilitation plan, which may include:
- Shockwave therapy or laser therapy to promote tissue healing.
- Functional movement training to restore joint coordination.
- Muscle strengthening and stability exercises.
- Balance and proprioception training.
- Joint mobility and flexibility exercises.
These combined methods aim to help patients regain full knee function and safely return to daily activities or sports.
2. Medication
During the early stages of injury, doctors may prescribe pain relief or anti-inflammatory medication to ease discomfort and reduce inflammation.
3. Surgical Treatment — Cruciate Ligament Reconstruction
Surgery is typically required only for complete anterior cruciate ligament (ACL) ruptures, as these cannot heal on their own.
In ACL reconstruction surgery, the surgeon removes the torn ligament and replaces it with a graft — usually taken from the patellar tendon or hamstring tendon.
The operation usually lasts 1 to 2 hours, and about 80% of patients are able to return to their previous level of activity after proper rehabilitation.
However, post-surgery physiotherapy remains essential to restore full mobility, muscle strength, and joint stability.
Can a Cruciate Ligament Tear Happen Again?
Yes. Studies show that 10–20% of patients who have had an ACL tear may experience a re-injury within a few years.
Common causes include:
- Inadequate rehabilitation after surgery.
- Returning to high-intensity sports too early.
- Not completing the full physiotherapy program.
Proper rehabilitation and muscle strengthening are crucial to reduce the risk of recurrence.
How Long Does Recovery Take?
Recovery time varies depending on the severity of the injury:
- Mild ACL injuries: usually recover within 3 to 6 months.
- Severe or complete tears: may require 9 to 12 months for full recovery, especially after reconstruction surgery.
Consistent physiotherapy and adherence to a guided rehabilitation plan greatly improve recovery outcomes.
Cruciate Ligament Rehabilitation Exercises
1. Terminal Knee Extension (TKE)
- Anchor a resistance band at a fixed point and loop it around the injured leg just below the knee.
- Keep the knee slightly bent, then slowly straighten it until fully extended.
- Hold for 2–3 seconds, then return to the starting position.
- Repeat 10–15 reps, 2–3 sets.
2. Backward Lunges
- Stand upright with feet shoulder-width apart.
- Step one foot backward and lower your body until the front knee reaches a 90-degree angle.
- Return to the standing position and repeat on the opposite side.
- Perform 8–12 reps per leg, 2–3 sets.
3. Hip Thrusts
- Sit on the floor with your upper back resting against a bench or sturdy surface, and feet flat on the floor.
- Slowly lift your hips upward until your thighs and torso form a straight line.
- Hold for 2–3 seconds, tightening your glutes, then lower back down.
- Perform 10–15 reps, 2–3 sets.
OneEssential Cruciate Ligament Tear Treatment Process
OneEssential ACL Rehabilitation and Physiotherapy Services
OneEssential provides specialized physiotherapy for cruciate ligament injuries, helping patients recover after injury or post-surgery.
Our rehabilitation programs include shockwave therapy, laser therapy, and progressive functional training — designed not only to relieve pain and accelerate healing but also to prevent premature return to high-intensity sports, which can worsen the injury or cause reinjury.
Book your appointment today to start your recovery journey with OneEssential!
Frequently Asked Questions About Cruciate Ligament Tears
Do All Cruciate Ligament Tears Require Surgery?
Not necessarily. Not all cruciate ligament tears require surgical intervention. For posterior cruciate ligament (PCL) or partial tears, especially in patients with low activity levels, physiotherapy and knee bracing may be sufficient to restore normal daily function.
However, for anterior cruciate ligament (ACL) tears — particularly among younger patients or athletes — surgery is often recommended due to the higher risk of knee instability.
ACL reconstruction surgery, followed by physiotherapy, is usually advised to restore joint stability and prevent future injuries.
Recent studies also show that non-surgical (conservative) treatment for complete ACL tears can sometimes achieve comparable results to surgery, depending on individual assessment and rehabilitation quality.
Can a Cruciate Ligament Tear Heal Naturally?
In some cases, yes — but it depends on the severity.
Mild or partial ligament injuries may heal naturally with appropriate physiotherapy and rest.
However, complete ACL tears often cause significant instability and require structured rehabilitation or bracing to restore knee function and prevent additional injuries such as meniscus or cartilage damage.
Without proper treatment, long-term complications and degeneration may occur.
How Can I Check If I Have a Cruciate Ligament Tear?
Doctors diagnose cruciate ligament injuries through a knee stability test to assess tibial movement relative to the femur.
They may also recommend an MRI scan to confirm ligament damage and detect any associated injuries such as meniscus tears or cartilage lesions.
Can I Exercise After a Cruciate Ligament Injury?
Acute phase (early stage): Avoid any high-impact activities or movements involving jumping, sudden turning, or twisting, as these can worsen the injury.
Rehabilitation phase: Under the guidance of a physiotherapist, low-impact exercises such as stationary cycling or swimming can be introduced progressively.
Full recovery: Return to high-intensity sports only after completing functional assessments confirming that the knee joint is stable and strong.
Source:
American Academy of Orthopaedic Surgeons (AAOS)：ACL Injury: Does It Require Surgery? https://orthoinfo.aaos.org/en/treatment/acl-injury-does-it-require-surgery/
What is ACL (anterior cruciate ligament) surgery? https://www.nhs.uk/tests-and-treatments/acl-anterior-cruciate-ligament-surgery/what-it-is/
British Orthopaedic Association, British Association for Surgery of the Knee, & British Orthopaedic Sports Trauma and Arthroscopy Association. (2020). Best practice for management of anterior cruciate ligament injuries. Retrieved September 16, 2025, from https://www.boa.ac.uk/static/88a4c3e3-df3e-4e51-a92e7d2f86d7d82a/Best-Practice-Book-for-management-of-Anterior-Cruciate-Ligament-injuries.pdf
Chong, C., Sit, C. H. P., Tse, P. W., Ngai, W. K., & Chan, K. M. (2015). Anterior cruciate ligament tear in Hong Kong Chinese patients: A case series. Hong Kong Medical Journal, 21(2), 131–136. Retrieved September 16, 2025, from https://www.hkmj.org/abstracts/v21n2/131.htm
Sanford Health. (2018). Posterior cruciate ligament (PCL) nonoperative rehabilitation guideline. Retrieved September 16, 2025, from https://www.sanfordhealth.org/-/media/org/files/medical-professionals/resources-and-education/3-pcl-nonoperative-rehabilitation-guideline.pdf