Adjustable or fixed loops in ACL surgery The GAP Study
Research type
Research Study
Full title
A Prospective, Randomised Study Investigating the use of a Fixed Loop versus an Adjustable Suspensory Loop in Anterior Cruciate Ligament Reconstruction - a Comparison of Clinical and Functional Outcome. The GAP Study.
IRAS ID
225470
Contact name
Chris Gardner
Contact email
Sponsor organisation
RD+E Hospital NHSFT
Duration of Study in the UK
5 years, 8 months, 1 days
Research summary
Summary of Research:
The anterior cruciate ligament (ACL) is one of the major stabilising ligaments in the knee. If torn, younger and sportier patients will often have this ligament reconstructed to allow them to return to sport with a knee joint that they can trust.
Hamstring tendons are taken from the back of the knee and create a graft to replace the torn ACL. A tunnel is drilled in the lower end of the thigh bone, and the upper end of the shin bone and the graft passes through this. On the shin bone side it is fixed in place using a screw. In the thigh bone, it is attached to a device known as a suspensory loop which passes through the tunnel and is held in place via a small metal button.
The length of the graft and the tunnels in the bone vary. It is important to get a good length of the graft material in both. With the fixed loop system, once the metal button attached to the thigh bone is in place, the length of the loop cannot be adjusted and the amount of hamstring graft in the bone tunnels cannot be changed. The adjustable loop allows the amount of graft in either bone tunnel to vary to ensure sufficient graft is accurately placed.
Patients for inclusion will be identified by their surgeon and if they consent will be randomly allocated to receive one of the 2 ACL reconstruction options as outlined above. We will monitor their progress for 2 years after the operation examining the results with questionnaires to measure how well the patients feel their knee is performing, and tests to measure knee function. All aspects of their surgical care will be as routine practice apart from the decision to use an adjustable or fixed suspensory loop.Summary of Findings:
Thank you to study participants:
We would like to acknowledge and thank all the patients who took part in this study. Their willingness to participate made an important contribution to improving the understanding of ACL femoral graft fixation. We are very grateful for the time and commitment they gave to this research.Study Title:
A Prospective, Randomised Study Investigating the use of a Fixed Loop versus an Adjustable Suspensory Loop in Anterior Cruciate Ligament Reconstruction - a Comparison of Clinical and Functional Outcome. The GAP Study.Who carried out the research?
This research was carried out by staff at the Exeter Knee Reconstruction Unit based at the Royal Devon University Healthcare NHS Foundation Trust. The study was sponsored by the Research Department at the Royal Devon University Healthcare NHS Foundation Trust.Public involvement in the study:
Patients were actively involved in designing the study. They reviewed the patient information leaflet and consent form to ensure that the information was clear and easy to understand. Our patient representatives emphasised the importance of making sure participants were fully informed about what taking part would involve, including the clinical assessments and the time commitment. All of their suggestions were incorporated into the final materials provided to participants.Where and when the study took place:
The study was conducted at Royal Devon University Healthcare NHS Foundation Trust:
• The operating theatres
• The orthopaedic outpatient department
The study ran from July 2017 to December 2024.Why was the research needed?
During ACL reconstruction surgery, the ACL graft needs to be securely fixed inside the thigh bone. There are different devices available to do this, but it was not known whether one type provides better knee stability or leads to a better recovery.
This study aimed to help surgeons and patients make informed choices by comparing two commonly used devices:
• a fixed-length suspensory loop, and
• an adjustable-length suspensory loop.What were the main questions the study looked at?
The study aimed to answer:
1. Does one type of device lead to better knee stability after ACL reconstruction?
2. Are there any differences in recovery or patient-reported outcomes between the two devices?
3. Are both devices equally effective and safe for patients?What did the study find? (Results)
A total of 164 patients with ACL injuries took part in the study. Half of them (82 patients) were randomly assigned to receive the fixed-loop device, and the other half (82 patients) received the adjustable-loop device. The two groups were very similar at the start of the study, with no important differences in age, gender, or other treatments they were receiving.Of these, 121 patients completed their 1-year follow-up assessments, which were used to look at the main outcomes of the study. Their average age was 31 years, and around 62% were male. At follow-up, 58 participants had received the fixed-length device and 63 had received the adjustable-length device.
The study looked at how stable participants’ knees were by using a device that gently applied pressure to the leg and measured how much the knee moved. This allowed us to assess knee looseness, known as “laxity.”One year after surgery, the results showed that the operated knees were equally stable in both groups. There were no meaningful differences between the fixed-length and adjustable-length devices.
Participants also completed questionnaires about their pain, symptoms, everyday function, and ability to return to sport. These included the IKDC, Lysholm score, KOOS, and Tegner activity scale. There were no differences between the two groups in any of these patient-reported outcomes.
What do these results mean? (Conclusion) This is the first study to directly compare these two ACL graft fixation devices in a randomised and blinded way. The results clearly show that:
• Both devices perform equally well in stabilising the knee after ACL reconstruction.
• Patients reported similar levels of knee function and recovery, regardless of which device they received.
• There is no evidence that one device leads to better outcomes than the other.
These findings are important for helping surgeons and patients choose between fixation devices, knowing that both options are safe and effective. The study also provides new reference data on typical knee stability measurements one year after ACL reconstruction, which may be useful for future research and clinical practice.The study findings have been presented at national knee conferences, and the full manuscript has now been submitted to a peer-reviewed journal.
REC name
Wales REC 1
REC reference
17/WA/0169
Date of REC Opinion
13 Jun 2017
REC opinion
Further Information Favourable Opinion