Tendon Graft Fixation Techniques in ACL Surgery: Self-Tapping Screw and Adjustable-Loop Button

The ACL surgery is common in orthopedic surgery, especially among athletes and physically active people. With advances in sports medicine, the operation no longer involves only replacing the ligament; its success now depends substantially on the technique used to secure the tendon graft inside the bone. The main devices used at this stage include the self-tapping interference screw and adjustable-loop button, two modern techniques that secure the graft inside the bone tunnel in either the femur or tibia.

This article examines tendon graft fixation techniques in ACL surgery in detail, explaining each device separately, comparing their advantages and disadvantages, and analyzing how these techniques improve surgical outcomes and accelerate the return to activity.

 ACL Surgery and Graft Fixation

When the anterior cruciate ligament tears, it is usually replaced with a tendon graft taken either from the patient's own body (autograft) or from a donor (allograft). This graft is inserted into two bone tunnels drilled precisely in the femur and tibia. It must be secured firmly to prevent movement or slipping while the tissues heal. The greatest challenge is choosing the ideal fixation method, which is where modern techniques are important.

Self-Tapping Interference Screw

This type of screw is designed specifically to secure the tendon graft inside the bone tunnel by pressing it sideways against the tunnel wall. The screw is inserted beside the graft, producing direct pressure that holds the graft against the bone and secures it in place.

Advantages of the Self-Tapping Interference Screw

• Strong mechanical fixation: provides high immediate stability that prevents graft movement during the initial healing stage.
• Ease of use: its self-tapping design requires no advance preparation or dedicated threading, reducing surgical time.
• Multiple material options: available in various materials, such as titanium or bioabsorbable materials.
• Good compatibility with autografts: widely used with tendon grafts taken from the patellar tendon or hamstring.

Disadvantages of the Self-Tapping Interference Screw

• Risk of graft damage: in some cases, excessive screw pressure may cut or damage the graft, especially if it is thin or uneven.
• Possible graft displacement: when used in an incorrectly sized tunnel or fragile bone, fixation may be lost.
• Requires a highly precise angle: an incorrect insertion angle may weaken fixation or cause the screw to emerge partially from the tunnel.

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Adjustable-Loop Button

This device is secured at the upper end of the graft, usually in the femoral tunnel. It consists of a small metal button pulled through the bone tunnel and locked on the other side of the bone, while the graft is tightened and secured with an adjustable loop suture.

Advantages of the Adjustable-Loop Button

• Modern technique that does not damage the graft: it does not place direct pressure on the tendon fibers as a screw does.
• Adjustable length: allows graft tension to be adjusted during surgery, ensuring ideal tension.
• Reduced risk of movement inside the tunnel: its precise mechanical design provides excellent dynamic stability.
• Effective in complex casesespecially in ACL Reconstruction after a previous surgery has failed or when bone deformities are present.

Disadvantages of the Adjustable-Loop Button

• Relatively complex to apply: requires specialized surgical training and experience using tensioning and fixation instruments.
• Risk of early slippage: if the suture is not tightened sufficiently, the graft may slip inside the tunnel.
• Higher cost: this technique is more expensive than the self-tapping interference screw, which may limit its use in some institutions.

You may also be interested in:- Types of Tendon Grafts in ACL Surgery

 Comparison of the Two Techniques

• Item	Self-Tapping Interference Screw	Adjustable-Loop Button
  Fixation Type	Mechanical lateral compression	Dynamic upper tension
  Fixation Site	Usually in the tibial tunnel	Usually in the femoral tunnel
  Graft Compatibility	Ideal for rigid grafts	Ideal for soft grafts
  Ease of Use	Relatively easy	Requires experience
  Risk of graft damage	Higher	Very low
  Ability to Adjust Tension	Limited	High
  Cost	Low to moderate	Relatively high
  Reuse in Complex Surgery	Moderate	Excellent

 How Does the Fixation Technique Affect Surgical Outcomes?

• The success of ACL surgery depends not only on surgical skill but also on the quality of the graft's mechanical fixation. Choosing the right technique determines how well the graft integrates with the bone and reduces the likelihood of ligament laxity or surgical failure over time. Recent studies indicate that the adjustable-loop button allows greater adjustment of tension and reduces problems with early rupture, while the self-tapping screw remains the best option for thick grafts and patients with moderate activity levels.

Some surgeons now combine the two techniques, securing one end with a screw and the other with an adjustable-loop button to achieve the best mechanical stability. Hybrid devices combining a screw and adjustable suture have also emerged, along with bioabsorbable materials that reduce the need for future surgery.

In conclusion, given the major advances in orthopedic surgical techniques, tendon graft fixation in ACL surgery clearly plays a central role in determining the operation's outcome and speed of recovery. The self-tapping interference screw is an effective option when direct stability is needed, while the adjustable-loop button offers more precise control and ideal tension for different clinical cases. The surgeon must choose the most appropriate device based on the graft type, bone tunnel shape and medical team's experience. Continued study and precise evaluation of each patient remain the foundation for achieving the best surgical and functional outcomes.