ACL Tears: Partial vs. Complete: When Is Surgery Needed?

ACL injuries are one of the most significant knee injuries in sport, especially in gymnastics, where cutting, landing, and pivoting demands are high.

Not all ACL tears are the same. Understanding the difference between partial and complete tears, and when surgery is actually necessary, is key to making the right decision for both recovery and long-term performance.

Understanding ACL Injuries

The ACL (anterior cruciate ligament) helps stabilize the knee, particularly during:

• Cutting

• Pivoting

• Landing

ACL injuries exist on a spectrum:

• Mild sprain: ligament is stretched but still intact, with minimal instability

• Partial tear: some fibers are torn, but part of the ligament remains intact

• Complete rupture: the ligament is fully torn, often resulting in significant instability

Clinical tests such as the Lachman test, anterior drawer, and pivot shift help determine the integrity of the ligament and the level of instability.

Partial ACL Tears

Partial ACL tears are less common but can sometimes be managed without surgery.

What They Look Like:

• Often classified as Grade II injuries

• Ligament is stretched or partially torn, but not fully disrupted

• May still feel stable depending on severity

Treatment Approach:

Many partial tears can be successfully managed with conservative treatment, including:

• Strength training (quadriceps and hamstrings)

• Neuromuscular control and stability work

• Activity modification

When Surgery May Be Considered:

• Persistent instability or “giving way”

• High-grade partial tears

• Failure to progress with structured rehabilitation

Close monitoring is essential, as some partial tears, especially in younger, active athletes, can progress to complete ruptures over time.

Complete ACL Ruptures

Complete ACL tears typically result in mechanical instability of the knee.

What They Look Like:

• Full ligament rupture

• Episodes of instability with movement

• Difficulty with cutting, pivoting, and sometimes even daily activities

Treatment Considerations:

Individuals who experience instability during:

• Walking

• Stairs

• Squatting

• Sport-specific movement

are more likely to benefit from ACL reconstruction surgery.

Who Typically Chooses Surgery:

• Young, active individuals

• Athletes in cutting and pivoting sports (like gymnastics)

• Those seeking a full return to high-level performance

Non-surgical management may still be an option, but typically requires modifying activity levels and avoiding high-risk movements.

The Role of Athlete Goals & Function

Treatment decisions are not based on imaging alone—they depend heavily on function, symptoms, and goals.

High School Gymnasts

• If the knee is stable, with no swelling, locking, or giving way, a trial of 8–12 weeks of structured rehab is often appropriate for partial tears

• Surgery is more commonly considered with complete tears or ongoing instability, especially if full return to sport is the goal

NCAA/Competitive Athletes

• Higher performance demands often lead to surgical reconstruction when instability is present

Elite Athletes

• Surgical reconstruction is frequently recommended to:

  • Maximize performance

  • Reduce risk of further injury (meniscus or cartilage damage)

  • Ensure long-term joint stability

    
    

Non-Surgical Management

Non-surgical care may be appropriate for:

• Stable partial tears

• Lower-demand individuals

• Athletes willing to modify activity

Rehabilitation focuses on:

• Quadriceps and hamstring strength

• Neuromuscular control

• Movement quality and stability

Success depends on maintaining stability and avoiding episodes of giving way.

Why This Matters

The biggest risk after an ACL injury isn’t just the ligament, it’s instability.

Repeated instability can lead to:

• Meniscus damage

• Cartilage injury

• Long-term joint degeneration

This is why decision-making must go beyond “tear vs. no tear” and focus on:

• Function

• Stability

• Sport demands

Bottom Line

• Partial ACL tears: often begin with conservative care if the knee is stable

• Complete ACL ruptures: frequently benefit from reconstruction, especially in athletes

• Instability, not just imaging, drives the decision

• Treatment should always be individualized based on goals, function, and sport demands

References:

1. ACL Injury: Does It Require Surgery? OrthoInfo. American Academy of Orthopaedic Surgeons; 2026.

2. Variations in common operations in athletes and non-Athletes. PMC. 2022.

3. A PT’s Guide to Rehabilitation After ACL Surgery. EliteLearning.

4. Do You Need Surgery for a Partially Torn ACL? Biology Insights.

5. Appropriate Use Criteria for Treatment of ACL Injuries. AAOS.

6. Identification of characteristics of patients who choose operative vs non-operative management after ACL injury. Sports Med-Open.