Hello, my name is Daniel Song, and I'm an orthopedic surgeon from Walter Reed National Military Medical Center in Bethesda, Maryland. None of these disclosures are relevant to this presentation. For slides with videos, please press the speaker button at the bottom of the slide to play the audio file. This is what I will be covering in this presentation. I will focus on the two most common methods of ACL tibial fixation, but will also cover additional methods. ACL reconstruction is a very common surgery. Stable fixation is paramount to the success of this surgery. The tibial fixation is particularly important because of the lower bone marrow density than in the femur. Tibial fixation aims to provide secure fixation that avoids displacement, allows for the integration of the graft into the tibial tunnel, and withstands the stress of early physical therapy. There are a lot of different fixation options. Many standard fixation methods have biomechanical and clinical data to support their use. It is crucial to be familiar with all techniques in case your primary or secondary preferred fixation method is compromised. Interference screws are one of the most common modes of tibial fixation. This method provides compression of the graft against the cancellous tibial tunnel wall. There are many screw options with their advantages and disadvantages. As a whole, interference or compression tibial fixation provides aperture or intratunnel fixation that theoretically provides decreased graft tunnel micromotion and tunnel widening. Some potential disadvantages are listed here and include graft damage by the screw threads during insertion, graft slippage as you are placing tension on the graft in the opposite direction the screw is advancing, it is less common in the tibia but screw tunnel divergence is also a potential disadvantage. Metal interference screws can make subsequent MRIs less helpful and there is some evidence of screw breakage, osteolysis, and bone reaction to the various material of non-metal screws. Overall, there is biomechanical and clinical evidence to support the use of interference screws for tibial fixation in ACL reconstruction. Sensory tibial fixation is another common method of ACL tibial fixation with strong biomechanical and clinical studies supporting its effectiveness. Theoretically, it allows 360 degrees of graft healing to the tibial tunnel. Other advantages include that it is minimally evasive, allows for re-tensioning depending on the design, and provides strong cortical fixation rather than the mostly cancellous fixation that occurs with interference screw fixation. Some disadvantages include increased graft tunnel motion due to the bungee cording or windshield wiping causing tunnel widening. A less common method of tibial fixation include a sheath and a screw. Theoretically, this provides 360 degree graft compression to the tunnel wall while also minimizing graft tunnel micromotion and tunnel widening similar to interference fixation. This type of tibial fixation has disadvantages similar to interference screw fixation including graft damage. One paper has shown an increase in infection with this type of tibial fixation and studies are showing no difference in biomechanical and clinical differences compared to an interference screw type fixation. Anecdotally, certain sheath and screw constructs can be complicated to remove in revision circumstances. Screw and washer is another less common method of ACL tibial fixation. The washer can be smooth or spiked and provides circumferential tunnel healing but has been associated with hardware prominence and can be difficult to remove. This can also be utilized for backup or supplementary fixation. This type of fixation requires sutures from the ACL graft to be tied over a post. It relies on the strength of the suture as well as the strength of the knot. There are many screw options to include cortical and cancellous. While this method is technically simple and there is no risk of graft damage seen in interference fixation, there are concerns for tunnel widening, hardware irritation, and inferior biomechanical properties. This can also be used as backup fixation. This is another method of both primary or secondary ACL tibial fixation. It is relatively easy to use and may decrease convergence with other tunnels with concomitant procedures during ACL reconstruction. Similar to other fixation methods, there is a risk of hardware irritation and graft damage, particularly with grafts with bone blocks. While the utilization varies from surgeon to surgeon and case dependent, there are many supplemental fixation options in ACL reconstructions. Some of these options include a suture anchor, post and screw, screw and washer, as well as cortical fixation. In conclusion, tibial fixation is a critical step in ACL reconstruction surgery. There are many options for tibial fixation, each with its advantages and disadvantages. It is important to understand how each technique can fit into a different surgical situation and is worthwhile to be comfortable with all techniques so you can be proficient if the circumstance arises. These are my sources.

ACL tibial fixation

interference screws

cortical fixation

orthopedic surgery

ACL reconstruction

sensory tibial fixation

graft integration