What causes an anterior cruciate ligament (ACL) injury in the knee?

Anterior cruciate ligament (ACL) injury of the knee may result from physiological factors or pathological conditions, such as meniscus injury or patellar dislocation. Appropriate management should be selected based on the specific cause. The detailed analysis is as follows:

I. Physiological Factors

If the injury is caused by sudden knee twisting, jumping, falling, or forced knee extension—situations that place excessive stress on the knee—knee immobilization is required. External fixation with a cast or brace should be applied as directed by a physician.

II. Pathological Factors

1. Meniscus Injury

If ACL injury results from traction due to meniscus damage, and the affected area is relatively small, external immobilization using a cast or brace is recommended. Additionally, pain relief can be achieved with medications such as diclofenac sodium sustained-release tablets, acetaminophen sustained-release tablets, or celecoxib capsules, as prescribed. If the meniscus injury is severe and medication proves ineffective, surgical treatment options such as arthroscopic meniscus repair or meniscectomy may be considered under medical advice.

2. Patellar Dislocation

If the ACL injury is secondary to patellar dislocation, external fixation with a brace or cast should be used according to medical instructions. Medications such as compound shaotong capsules, shujin huoxue tablets, or huoxue zhitong capsules may be taken as prescribed to promote blood circulation, reduce swelling, and relieve pain. In cases of severe ligament damage, surgical interventions such as lateral release or open reduction with internal fixation may be recommended by a physician.

In addition, ACL injury could also stem from congenital structural defects or insufficiency of the anterior cruciate ligament. Patients are advised to seek timely medical evaluation for accurate diagnosis.