RecruitingInterventional

The ACL Repair vs Reconstruction Study (ACL STARR)

The anterior cruciate ligament (ACL) is a tough band of tissue that keeps your knee steady. When it tears, your knee can give way, cause pain, and increase the risk of future joint problems. Standard surgery usually involves 'reconstruction', where a surgeon replaces the torn ligament with a piece of tendon taken from another part of your body, like your hamstring. A newer option is 'repair', where the surgeon stitches your own torn ligament directly back onto the bone, saving your natural tissue. The ACL STARR study is an NHS trial comparing these two operations in people aged 14 and older. Participants are placed by chance into one of the two surgery groups. Researchers will track their healing, pain levels, and knee stability for two years using simple questionnaires to determine which surgical approach works best.

At a glance

Status

Recruiting

Sponsor

Cambridge University Hospitals NHS Foundation Trust

Enrolment target

286

Start

03 Jul 2025

Estimated completion

30 Jun 2027

Anterior cruciate ligament injuries

What is this study about?

The knee is one of the hardest-working joints in the body. Running through the middle of it is the anterior cruciate ligament (ACL), a strong band of tissue that connects your thigh bone to your shin bone. It acts like a stabilising rope, stopping the bones from sliding out of place. Tearing the ACL is a common injury in sports and physical work. An unstable knee can give way, cause swelling, and lead to early arthritis if left unmanaged.

For many years, the most common operation has been ACL reconstruction. During this procedure, the surgeon creates a replacement ligament using a piece of tendon taken from elsewhere in your leg. While this works well, it means removing healthy tissue from another site and drilling larger holes into the bone. Modern surgical advances now allow some torn ligaments to be stitched directly back onto the bone instead. This is called an ACL repair. Repairing the natural ligament avoids taking tissue from other areas and may support a faster recovery, but doctors do not yet know which method provides better long-term results.

The ACL STARR trial is designed to answer this question fairly. By comparing repair directly against reconstruction, researchers want to see which operation leads to better knee strength, fewer complications, and better overall quality of life over two years. The findings will help future patients and NHS doctors make more informed choices about knee surgery.

Key takeaways

The study compares stitching a torn ACL (repair) with replacing it using other tissue (reconstruction).
Open to patients aged 14 and over with a recent proximal ACL tear.
Treatment is chosen randomly by a computer to ensure a fair scientific comparison.
Follow-up lasts for two years and is done via simple questionnaires completed from home.
Both operations carry standard surgical risks, and taking part does not require extra hospital visits.

Who may be eligible?

This trial is open to people aged 14 and over who have recently torn their ACL. To be eligible, your tear must be a specific type where the ligament has pulled directly away from the upper bone. This means your injury is physically suitable for either a repair or a reconstruction. You must also be happy to let a computer randomly choose which of the two operations you receive.

You cannot join the study if you have had major surgery on the same knee before, though minor keyhole checks or small cartilage trims are usually acceptable. You will also not be able to participate if you have severe tears in multiple knee ligaments at the same time, or if you have a serious injury to your other knee.

Your hospital orthopaedic team will review your knee scans and physical examination to confirm whether your specific tear pattern makes you suitable for the study.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am 14 years of age or older.
I have recently torn my anterior cruciate ligament (ACL).
My surgeon has confirmed my tear is suitable for either repair or reconstruction.
I have not had major surgery on this knee in the past.
I do not have severe damage to other main ligaments in the same knee.
I am happy to let a computer randomly decide which operation I receive.

Answer every question to see your result.

What does participation involve?

If you choose to take part, you will be randomly assigned to receive either an ACL repair or an ACL reconstruction. Both procedures are carried out in hospital under general anaesthetic by experienced surgical teams.

After your surgery, you will follow a standard knee rehabilitation plan. Taking part in the study does not require extra hospital visits beyond your normal NHS appointments. Instead, you will be asked to score your pain levels at 3 and 6 weeks after surgery. You will then complete simple questionnaires about your knee function, daily activities, and recovery at 6, 12, and 24 months. These surveys can be completed at home, either online or on paper. In total, your participation lasts for two years after your operation.

Potential risks and benefits

Both operations aim to restore knee stability, ease your symptoms, and help you return to your normal routine. However, because this is research, doctors cannot guarantee that one approach will be better than the other. Both surgeries carry typical risks, including knee stiffness, swelling, wound infection, blood clots, nerve irritation, or the possibility that the ligament tears again in the future. These risks are the same whether you join the study or have standard NHS knee surgery outside of it. Joining the study is completely voluntary, and you are free to withdraw at any time without your regular NHS care being affected.

Locations (20)

Cambridge University Hospitals NHS Foundation Trust
City only
Cambridge, England
Sheffield Children's NHS Foundation Trust
City only
Sheffield, England
University Hospitals Birmingham NHS Foundation Trust
City only
Birmingham, England
University Hospitals Coventry and Warwickshire NHS Trust
City only
Coventry, England
Nuffield Orthopaedic Centre
Approximate
Oxford, England
Lanarkshire University Hospitals
Unverified
Glasgow, Scotland
Barts Health NHS Trust
Unverified
London, England
Northumbria Healthcare NHS Foundation Trust
Unverified
North Shields, England
North Bristol NHS Trust
Unverified
Bristol, England
Sandwell & W Birmingham NHS Trust
Unverified
Birmingham, England
NHS Ayrshire and Arran
Unverified
Ayr, Scotland
Sheffield Teaching Hospitals NHS Foundation Trust
Unverified
Sheffield, England

Common questions

How is my type of surgery decided?

A computer programme uses random selection to assign you to either repair or reconstruction. This ensures both groups are balanced fairly so the results are accurate.

Will I need to travel to extra hospital visits?

No. Your clinic check-ups follow normal NHS care. The trial follow-ups are simple questionnaires that you can complete from home online or on paper.

Can teenagers take part?

Yes, young people aged 14 and older can take part, provided they and their parent or guardian agree and meet the medical requirements.

Is the repair surgery completely new?

Stitching ligaments has been done before, but modern techniques and tools are newer. While promising, doctors need this trial to confirm if it works as well as standard reconstruction.

What happens if I change my mind?

You can leave the study at any point. Deciding to withdraw will not change your relationship with your surgical team or the standard of care you receive.

How to find out more

Jennifer O'Callaghan

jennifer.ocallaghan@nihr.ac.uk +44 1223 768010 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.