ACL Graft Fixation - Wheeless' Textbook of Orthopaedics

- Discussion:
- see Arthrex, Mitek, Linvatec, Smith-Nephew
- in choosing a fixation technqiue consider the need for the following:
- circumferential (360 deg) healing of graft against tunnel wall (interference screws do not permit this);
- bioabsorbable material
- strong initial fixation (greater than 120-140 Newtons)
    - interference screw insertion:
             - typically a 8 x 25 mm screw will be selected;
- nitinol guide wire can be inserted thru the medial arthroscopic portal, or may be inserted thru a stab incision made in fat pad, below the portal;
- knee is flexed an additional 30 deg to facilitate insertion of Nitinol guide wire;
- a sheath is required to protect the tendinous portion of the graft from the screw threads;
    - appropriate graft tension:
- usually about 40 N or 10 lbs of tension is applied;
- typically graft is secured in 20-30 deg of knee flexion;
             - references
                    - Effects of Initial Tension and Anterior Load-Displacement Behavior of High-Stiffness ACL Graft Constructs.
                    - A Prospectively Randomized Double-Blind Study on the Effect of Initial Graft Tension on Knee Stability
                    - Viscoelasticity and temperature variations decrease tension and stiffness of hamstring tendon grafts following ACL reconstruction.
                    - Effects of Initial Graft Tension on the Tibiofemoral Compressive Forces and Joint Position After ACL Reconstruction.
                    - Effects of initial graft tension on clinical outcome after ACL reconstruction.    Autogenous doubled hamstring tendons connected in series with polyester tapes
                    - The Effect of Initial Graft Tension in ACL Reconstruction on the Mechanical Behaviors   of the Femur-Graft-Tibia Complex During Cyclic Loading
                    - A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the ACL
                    - Graft tension in ACL reconstruction. An in vivo study in dogs.
    - appropriate knee flexion during fixation:
             - if patient has gross instability to lachman and pivot shift then tensioning at 15 lbs at 30 deg is indicated;
- if patient has hyperextension of the knees on both sides or if graft tightens or shortens 5 mm or more with knee extension, then tension closer to full extension;
             - references:
                    - Loss of Knee Extension After Anterior Cruciate Ligament Reconstruction: Effects of Knee Position and Graft Tensioning

- references:

- Multistranded Hamstring Tendon Graft Fixation with a Central Four-Quadrant or a Standard Tibial Interference Screw for Anterior Cruciate Ligament Reconstruction.

- Reconstruction of the anterior cruciate ligament using bone-patellar tendon-bone graft with double biodegradable femoral pin fixation.

- The effect of soft-tissue graft fixation in anterior cruciate ligament reconstruction on graft-tunnel motion under anterior tibial loading.