Surgical Technique

ACL RECONSTRUCTION TECHNIQUE

Once harvested, the graft is then prepared for implantation. This involves trimming the tendon so that it most closely resembles the native ACL. This intra-operative preparation is typically done by a surgical assistant while the surgeon continues to prepare the knee for placement of the graft. Preparation also includes sizing the graft and placing sutures in the graft to aid in the passage of the graft into the knee joint.

While an assistant is preparing the graft, the surgeon begins the arthroscopic portion of the case. Small arthroscopic portal incisions are made on either side of the patellar tendon measuring about one centimeter each. These two incisions allow access to the entire knee joint, utilizing an arthroscope (a digital movie camera that is able to be sterilized) and specialized arthroscopic tools. The lateral portal (the incision on the outer-side of the patellar tendon) is typically used to insert the camera, while the medial portal is used to shuttle skinny tools in and out of the knee joint. The knee joint is then systematically examined, looking for any abnormalities. Possible injuries include articular cartilage damage or meniscal tears. Once these other areas are addressed, preparation of the bone tunnels is commenced.

As mentioned earlier, the ACL spans between the femur and the tibia. On either end, the ACL is attached via a complex combination of tissues. This allows the ACL to “grab onto” the bone. In the middle of the ACL the fibers are exclusively connective tissue that is stretchy (but only to a point) and pliable. As the ACL nears the bone there is a transition to a stiffer connective tissue that has “fibrocartilage”. Further closer to the bone the ACL actually becomes partially calcified, resulting in further stiffening. These spicules of bone extend all the way to the hard cortical bone surface where the ACL is anchored. Careful scientific studies over the last two decades have helped us understand where exactly the ACL attachment sites are located. Because no surgeon is able to sew the ACL to the bone with the requisite strength it would need to survive, we drill tunnels starting at the attachment sites and deeper into the bone. Conceptually, bony tunnels must be (very accurately!) placed at the precise locations of the native ACL. As mentioned, it’s “location, location, location” when it comes to performing the best possible ACL reconstruction. The tunnels are created with motorized drills that create holes that are typically 8 to 10 millimeters in diameter.

Once the tunnels are complete the graft is pulled within the tunnels. Major advances have occurred in our ability to fixate the graft within the tunnel. Presented above were the biomechanical data regarding the strength of the graft itself, but there are dozens of studies regarding the strength of the numerous fixation devices surgeons use to place the graft within the tunnels. Year after year new devices are brought to the market that are stronger and stronger, promising lower re-injury rates and better healing. I presently use the Biomet Togglec femoral fixation device, and the Cayenne tibial fixation device coupled with the BIomet Washerloc. Click here to see video demonstrations of device deployment.

Risks

Surgery always entails risks and benefits. For all the benefits of gaining normal stability of the knee there are some important considerations. No trip to the doctor is risk free, although the overall complication rate for ACL reconstruction is quite low. Major complications, such as heart attack, blood clots to the lungs, and deep infection to the knee joint are exceptionally rare. Minor complications, while still rare, include knee stiffness, superficial skin infections, tenderness around the knee, and numbness around the skin incisions. In the U.S., the overall infection rate for knee arthroscopy is 0.04 per cent, or 4 in 10,000; stated another way, 1 in 2,500 operations. The re-rupture of the reconstructed ACL is also rare, especially when one uses their own tissues for the graft. The failure rate of ACL reconstruction in the U.S. is less than 5% when using autograft tissues. Blood clots, or Deep Venous Thrombosis (DVT), can occur after surgery or trauma. The incidence of DVT is higher in obese patients, among smokers, among those who are sedentary (not moving), and in those who have a family history of DVT. Patients who have multiple risk factors are treated with blood thinners in the post-operative time period.