ACL Tear

Overview

The anterior cruciate ligament, commonly known as the ACL, is one of four major ligaments that stabilize the knee joint. It runs diagonally through the center of the knee, connecting the thighbone to the shinbone and preventing the tibia from sliding forward. When the ACL tears, the knee loses a critical source of rotational stability, which can make pivoting, cutting, and even routine walking feel unreliable.

ACL injuries are among the most common serious knee injuries, affecting an estimated 200,000 people in the United States each year. While they are closely associated with sports, ACL tears can happen to anyone. At our San Diego practice, we evaluate every ACL injury individually and always consider non-surgical treatment options before recommending reconstruction.

Causes

ACL tears typically result from sudden movements that place excessive stress on the ligament. The most common mechanisms include:

• Sudden deceleration or direction change — planting your foot and pivoting quickly, common in basketball, soccer, and football
• Awkward landings — coming down from a jump with the knee extended or twisted, frequently seen in volleyball, gymnastics, and skiing
• Direct contact — a blow to the side of the knee during a tackle or collision
• Falls — slipping on uneven surfaces or losing balance during physical activity
• Motor vehicle and workplace accidents — high-energy trauma can cause ACL tears along with other knee injuries

Women are two to eight times more likely to sustain an ACL tear than men in the same sports, which researchers attribute to differences in anatomy, muscle strength patterns, and hormonal factors. Understanding your personal risk factors can help inform prevention strategies.

Symptoms

An ACL tear often announces itself dramatically. Most patients report:

• A popping sensation or audible pop — many people hear or feel a distinct pop in the knee at the moment of injury
• Severe pain — immediate, sharp pain that may make it impossible to continue your activity
• Rapid swelling — the knee often swells significantly within the first few hours as blood fills the joint, a condition called hemarthrosis
• Loss of range of motion — difficulty fully bending or straightening the knee due to swelling and pain
• Instability — a feeling that the knee is giving way or buckling, particularly when attempting to pivot or change direction
• Tenderness along the joint line — pain when pressing along the inner or outer edges of the knee

Some patients with partial tears experience milder symptoms. Regardless of severity, any knee injury with swelling and instability warrants prompt medical evaluation.

Diagnosis

Accurate diagnosis begins with a thorough physical examination. Your orthopedic surgeon will assess the knee for swelling, tenderness, and range of motion, and perform specific stability tests such as the Lachman test and the pivot shift test to evaluate the integrity of the ACL.

An MRI is the gold standard imaging study for confirming an ACL tear. It provides detailed images of soft tissues, revealing the extent of the ligament injury and identifying any associated damage to the meniscus, cartilage, or other ligaments. X-rays may also be taken to rule out bone fractures.

Treatment Options

Not every ACL tear requires surgery. The right treatment depends on several factors, including the severity of the tear, your activity level, your age, and whether other structures in the knee are damaged. Our approach is to thoroughly evaluate your situation and present all options so you can make an informed decision.

Non-Surgical Treatment

Non-surgical management may be appropriate for patients with partial tears, lower activity demands, or those who do not participate in cutting and pivoting sports. A conservative treatment plan typically includes:

• Bracing — a functional knee brace provides external stability and protects the knee during daily activities and low-impact exercise
• Physical therapy — a structured rehabilitation program focuses on strengthening the muscles around the knee, particularly the quadriceps and hamstrings, to compensate for the injured ligament
• Activity modification — adjusting your exercise routine to avoid high-risk movements while maintaining overall fitness
• Anti-inflammatory medication — managing pain and swelling during the initial recovery period

Many patients, especially those whose daily activities do not involve aggressive pivoting or cutting motions, function well with a rehabilitated but ACL-deficient knee.

Surgical Treatment — ACL Reconstruction

When surgery is necessary, ACL reconstruction is the standard procedure. Rather than repairing the torn ligament, the surgeon replaces it with a graft, typically harvested from the patient’s own patellar tendon, hamstring tendon, or quadriceps tendon. In some cases, donor tissue may be used.

The procedure is performed arthroscopically through small incisions, which allows for less tissue disruption and a faster recovery compared to open surgery. During reconstruction, the graft is positioned to replicate the original ACL’s path and secured with biocompatible fixation devices.

Surgery is generally recommended for active individuals who wish to return to sports involving pivoting and cutting, patients with combined ligament injuries, and those who experience persistent instability despite physical therapy.

Recovery

Recovery from an ACL injury, whether treated surgically or conservatively, requires patience and commitment to rehabilitation.

Non-surgical recovery typically involves 3-6 months of progressive physical therapy before returning to full activity. Patients often notice significant improvement in stability within the first few weeks of dedicated strengthening exercises.

Post-surgical recovery follows a more structured timeline:

• Weeks 1-2 — rest, ice, elevation, and gentle range-of-motion exercises; most patients use crutches
• Weeks 2-6 — progressive weight bearing and increasing range of motion
• Months 2-4 — strengthening exercises, stationary cycling, and light jogging when cleared
• Months 4-6 — sport-specific training and agility drills
• Months 6-9 — gradual return to full sports participation based on strength testing and functional assessments

Prevention

While ACL tears cannot always be prevented, research has shown that neuromuscular training programs can significantly reduce the risk. Effective prevention strategies include:

• Strengthening the muscles around the knee — particularly the hamstrings and quadriceps
• Improving balance and proprioception — single-leg exercises and balance board training
• Practicing proper landing and cutting technique — bending the knees and hips during landings
• Warming up thoroughly before activity
• Wearing appropriate footwear for your sport and surface

If you have experienced a knee injury or are dealing with knee instability, contact our San Diego office for a comprehensive evaluation. Our team will work with you to determine the most effective treatment plan for your individual needs and goals.