Evolution of Technology

ACL Reconstruction

The first ACL reconstruction techniques were done by suturing the graft directly to the bone, however this did not allow for tensioning the graft and was overall a poor fixation technique. Tension on the reconstructive graft is extremely important for it to provide stability. Later, sutures that were attached to the graft were fixed to the bone by a screw.

The screw was a stronger fixation point and allowed for graft tensioning. Washers have been developed to help with fixation strength. Problems arose with the screw and washer systems as they can be symptomatic and in the unfortunate case of revision, reconstructions can be difficult to remove and potentially lead to bone loss. To reduce incision number and size, arthroscopic techniques have been developed to fixation. This includes interference screws and cortical buttons.

Interference screws work by producing large amounts of friction between the graft and the tunnel wall within each bone. This compression and friction prevent the graft from loosening. For cortical buttons the graft is attached to sutures which hold tension on the graft after being affixed to the bone by use of the implant. Cortical button fixation has been shown to provide the strongest load to failure of fixation techniques.

Evolution of Procedure

ACL Reconstruction

Historically the first ACL reconstructions were done through a large incision and putting part of a tendon taken from another part of the body into the knee to act as a stabilizer. However, as technology and surgery have advanced, current ACL reconstructions are performed arthroscopically. This means with small incisions around the knee and using a small camera that is placed into the joint.

The first procedures using arthroscopy were done with a single drill tunnel extending from the tibia into the femur. Usually, now two separate tunnels are drilled, one in the tibia and one in the femur, as this allows for improved recreation of the body’s normal path for the ligament. To recreate the ligament itself, two main tissue categories exist: autograft (tissue is taken from the patient themselves), and allograft (donated tissue from another person).

Autograft can come from the hamstring muscle tendons, quadricep muscle tendon, and patellar tendon. The quadriceps and patellar tendon options can have bone attached to the graft to help with healing. Each graft source has its advantages and disadvantages. Autograft often heals faster and there is not a risk for immune reaction. However, there is an associated risk of harvest site morbidity to include hamstring weakness, anterior knee pain, and a limited number of sources.

Allograft has the benefit of not having harvest site morbidity but is slower to heal and 1 in a million chance of viral transmission between donor and recipient. For most patients, there is not a significant difference in outcomes between allograft and autograft reconstructions.

Evolution of Diagnosis

ACL Rupture

Anterior cruciate ligament (ACL) ruptures are extremely common sports-related injuries. These often occur due to non-contact pivoting motions or after direct hits to the outside of the knee while playing sports. Patients will often feel a pop with sudden onset pain and significant swelling of the knee and inability to bear weight.

The ACL normally functions to prevent movement of the tibia (shin bone) forward in relation to the femur (thigh bone) and provides stability to the knee during rotational movements such as pivoting and cutting. In children, these types of injuries rarely can be treated direct repair of the ligament, but there is a high rate of failure.

The vast majority of patients a reconstructive procedure is required. While the option to treat these without reconstruction exists, most healthy and active patients greatly benefit from reconstruction.