Returning to sport after ACL surgery is often one of the biggest goals for young athletes recovering from a knee injury. Whether it’s returning to competitive sport, school sport, or regular physical activity, recovery after ACL reconstruction involves more than simply waiting for the knee to heal.

Strength, movement quality, confidence, and overall knee function all play an important role in determining when an athlete may be ready to return safely to activity.

Dr Alex Nicholls has contributed to research examining strength recovery and muscle balance in paediatric patients following ACL reconstruction surgery.

What Is ACL Reconstruction?

ACL reconstruction is surgery performed to restore stability to the knee after an anterior cruciate ligament (ACL) injury.

The ACL is one of the key stabilising ligaments of the knee and is commonly injured during sports involving:

• Pivoting

• Jumping

• Rapid direction changes

• Twisting movements

Sports commonly associated with ACL injuries include:

• Soccer

• AFL

• Basketball

• Netball

• Rugby

• Skiing

Following surgery, rehabilitation plays a major role in recovery and return to sport.

Why Is Return to Sport Important?

For many young athletes, returning to sport is a major milestone after ACL surgery.

However, returning too early — before strength, stability, and movement control have recovered adequately — may increase the risk of:

• Re-injury to the ACL

• Injury to the opposite knee

• Ongoing instability

• Reduced performance

Because of this, return to sport is usually based on recovery progression rather than a fixed timeline alone.

What Does ACL Rehabilitation Involve?

ACL rehabilitation is typically divided into stages.

Early Recovery Phase

The initial focus is on:

• Managing swelling

• Restoring knee movement

• Walking mechanics

• Protecting the surgical reconstruction

Strength and Control Phase

As recovery progresses, rehabilitation shifts toward:

• Quadriceps strengthening

• Hamstring strengthening

• Balance and control exercises

• Improving movement quality

Restoring strength around the knee is particularly important in young athletes returning to sport.

Sport-Specific Rehabilitation

Later stages of rehabilitation may involve:

• Running progression

• Jumping and landing drills

• Agility exercises

• Pivoting movements

• Sport-specific training

The aim is to gradually reintroduce the physical demands required for sport participation.

Why Does Strength Matter After ACL Surgery?

Strength recovery is an important part of ACL rehabilitation.

Research has shown that deficits in:

• Quadriceps strength

• Hamstring strength

• Limb symmetry

may persist even after an athlete feels subjectively “better.”

Reduced strength can affect:

• Knee stability

• Movement control

• Jumping and landing mechanics

• Confidence during sport

This is one reason why return-to-sport assessment often includes formal strength testing.

What Are Hamstring-to-Quadriceps Ratios?

The hamstrings and quadriceps work together to stabilise the knee joint.

Following ACL reconstruction, restoring an appropriate balance between these muscle groups is important for:

• Knee function

• Stability

• Movement efficiency

• Return to sport readiness

Research examining hamstring-to-quadriceps ratios helps clinicians better understand how young athletes recover after ACL surgery.

Dr Alex Nicholls has contributed to research investigating quadriceps strength and hamstring-to-quadriceps ratios in paediatric patients following ACL reconstruction.

Does Recovery Differ in Children and Teenagers?

Yes.

Children and adolescents are not simply “small adults.” Recovery considerations may differ due to:

• Growth and skeletal maturity

• Sport participation levels

• Movement patterns

• Psychological readiness

• Ongoing physical development

This is why rehabilitation and return-to-sport planning in younger athletes is often individualised.

How Long Does Return to Sport Take?

Recovery timelines vary between individuals.

Factors influencing recovery include:

• Type of ACL injury

• Associated meniscal or cartilage injuries

• Surgical technique

• Rehabilitation progression

• Strength recovery

• Sport demands

Return to sport is generally guided by:

• Functional testing

• Strength assessment

• Knee stability

• Movement quality

• Overall recovery progression

Rather than relying on a single timeframe, clinicians assess multiple factors before clearing an athlete for return to higher-level activity.

Why Is Return-to-Sport Testing Important?

Returning to sport involves more than simply feeling pain-free.

Return-to-sport testing may include assessment of:

• Strength

• Balance

• Jumping mechanics

• Agility

• Limb symmetry

• Movement control

These assessments help determine whether the athlete is physically prepared to return to sport safely.

Current Research in ACL Recovery

Research in ACL rehabilitation continues to evolve, particularly in younger athletes.

Areas of ongoing research include:

• Strength recovery after ACL surgery

• Return-to-sport outcomes

• Muscle balance and function

• Re-injury risk

• Rehabilitation progression in adolescents

Dr Alex Nicholls has contributed to research examining strength recovery and hamstring-to-quadriceps ratios following paediatric ACL reconstruction.

Summary

Returning to sport after ACL surgery is a gradual process that involves more than healing alone. Strength, movement quality, stability, and functional recovery all play an important role in determining when a young athlete may be ready to return safely to activity.

ACL rehabilitation and return-to-sport planning are typically individualised, particularly in children and teenagers where growth and development remain important considerations.

This article is based in part on Dr Alex Nicholls’ research examining strength recovery and hamstring-to-quadriceps ratios following ACL reconstruction in paediatric patients.

Read the full publication:
Quadriceps Strength and Hamstring-to-Quadriceps Ratios in Pediatric Patients After ACL Reconstruction: Revisiting Norms from Adult Data