Anterior cruciate ligament (ACL) injuries are among the most common knee injuries seen in active teenagers and adults, particularly in sports involving pivoting, cutting, jumping, or sudden changes in direction. One of the first questions many patients ask after diagnosis is whether surgery is necessary.

The answer is not always straightforward.

While ACL reconstruction surgery is an appropriate option for some patients, not every ACL injury requires surgical treatment. Management depends on several factors including symptoms, knee stability, activity goals, associated injuries, and how the knee responds to rehabilitation.

Dr Alex Nicholls has contributed to research investigating which patients may be able to safely manage an ACL injury without surgery, and which patients are more likely to benefit from reconstruction.

What Is the ACL?

The anterior cruciate ligament (ACL) is one of the major stabilising ligaments of the knee. It helps control rotational movement and forward movement of the tibia relative to the femur.

When the ACL is torn or ruptured, the knee can become unstable, particularly during twisting or pivoting movements.

How Do ACL Injuries Happen?

ACL injuries commonly occur during:

• Soccer

• AFL

• Basketball

• Netball

• Skiing

• Rugby

In many cases, the injury occurs without direct contact.

Typical mechanisms include:

• Sudden changes in direction

• Landing awkwardly from a jump

• Twisting while the foot is planted

• Rapid deceleration movements

Symptoms of an ACL Tear

Common symptoms of an ACL injury include:

• A popping sensation at the time of injury

• Rapid swelling within the first 24 hours

• Pain and difficulty continuing activity

• Instability or “giving way” episodes

• Reduced confidence in the knee

Some people regain day-to-day function relatively quickly, while others continue to experience instability.

Does Every ACL Tear Require Surgery?

No.

Some patients are able to return to daily activities and even some sports with structured rehabilitation alone. Others continue to experience instability despite physiotherapy and strengthening.

Treatment decisions are based on several factors rather than MRI findings alone.

Factors That Influence ACL Treatment Decisions

Knee Stability

One of the main considerations is whether the knee feels stable during activity.

Some patients experience repeated episodes of the knee “giving way,” particularly during pivoting movements. Ongoing instability can increase the risk of further injury to the meniscus or cartilage.

Activity Level and Sporting Goals

Patients involved in high-demand sports that involve cutting, twisting, or pivoting are often more likely to consider ACL reconstruction surgery.

Examples include:

• Soccer

• Basketball

• Netball

• AFL

• Skiing

For patients with lower physical demands, rehabilitation alone may sometimes be appropriate.

Age and Skeletal Maturity

In children and adolescents, treatment planning also takes growth plates into consideration.

Paediatric and adolescent ACL injuries require careful assessment to balance knee stability, future activity, and growth-related factors.

Associated Injuries

ACL tears can occur alongside:

• Meniscal tears

• Cartilage injuries

• Bone bruising

• Other ligament injuries

The presence of associated injuries may influence treatment recommendations.

What Is Non-Surgical ACL Management?

Non-surgical management generally involves:

• Physiotherapy

• Strengthening programs

• Neuromuscular training

• Gradual return to activity

The goal is to improve strength, movement control, and knee stability.

Some patients function well without surgery, while others continue to experience instability despite rehabilitation.

What Is ACL Reconstruction Surgery?

ACL reconstruction involves replacing the torn ligament using a graft.

The procedure aims to restore knee stability and allow return to activity where appropriate.

There are different graft options and surgical techniques depending on the patient’s age, anatomy, sporting demands, and associated injuries.

What Does Recovery After ACL Reconstruction Involve?

Recovery after ACL surgery is gradual and structured.

Early Recovery

Focus is placed on:

• Swelling management

• Restoring movement

• Protecting the knee

Mid-Stage Rehabilitation

Rehabilitation progresses toward:

• Strength rebuilding

• Balance and control

• Movement quality

Return to Sport

Return to sport is based on:

• Strength testing

• Functional assessment

• Knee stability

• Movement confidence

Rather than a fixed timeline, progression is guided by recovery milestones.

What Does Current Research Show?

Research is increasingly showing that ACL injuries do not all follow the same pathway.

Some patients may cope well with structured rehabilitation alone, while others are more likely to benefit from surgical reconstruction due to instability or sporting demands.

Dr Alex Nicholls has contributed to research examining which patients may safely avoid surgery and which patients are more likely to require reconstruction for long-term knee stability and function.

When Should You See a Knee Specialist?

It is worth seeking specialist assessment if you experience:

• Ongoing instability

• Recurrent swelling

• Difficulty returning to sport

• Persistent pain

• Locking or catching symptoms

An assessment can help determine:

• Whether the ACL is injured

• Whether associated injuries are present

• What treatment options are appropriate

Summary

Not all ACL injuries require surgery. Treatment depends on the individual patient, their symptoms, stability, activity goals, and associated injuries.

For some people, structured rehabilitation may provide sufficient stability and function. For others, ACL reconstruction may be the more appropriate option to support return to higher-level activity and reduce ongoing instability.

This article is based in part on Dr Alex Nicholls’ research investigating which ACL injuries may be safely managed without surgery versus those more likely to benefit from reconstruction.

Read the full publication:
Do all ACL injuries need surgery? Prospectively identifying patients with ACL injury that can be safely managed with a structured non-surgical treatment program versus those in whom surgery is a safer option