Updated: Nov 3, 2022
This month's blog is written by Dr. Jason Wilcox of Orthopedic Physicians Associates. Dr. Wilcox is an orthopedic surgeon that has a special interest in ACL reconstruction. For further info on Dr. Wilcox and further specialties please click on the link at the bottom of the blog.
ACL reconstruction is one of the most common procedures performed in orthopedics. The rate at which ACLs are being injured and thus reconstructed continues to increase. This increase is mostly being driven by high-level athletics being performed by an ever-widening age spectrum with an ever-increasing expectation of performance over a longer period.
When an injury occurs, the athlete often reports hearing and/or feeling a “pop.” In the setting of an ACL injury, most athletes develop the rapid onset of swelling, typically a hemarthrosis, where blood fills the knee after injury. The most common mechanism of injury is a non-contact pivoting mechanism that accompanies a sudden change in speed via deceleration and/or changes in direction. A second common mechanism is via a direct blow to the knee. Common sports of injury include soccer, basketball, skiing, and football, but can occur in a multitude of sports and even non-athletic endeavors.
Though a small number of athletes can return to the sport of injury without surgical treatment of an ACL-deficient knee, most athletes wishing to return to cutting sports require surgical treatment. Additionally, there is a cohort of patients that require surgical stabilization to prevent knee instability even during non-athletic pursuits including activities of daily living. Another consideration when treating an ACL-deficient knee is the potential risk to other structures within the knee. The ACL is the primary restraint to anterior tibial translation as well as internal rotation. In its absence, the medial meniscus, which is a secondary stabilizer in an otherwise structurally sound knee, becomes a more primary restraint due to its anatomic location. Given this new level of stress on the meniscus, the risk of developing a tear continues to increase over time. Additionally, given the increased translation of the tibia and the risk of developing a medial meniscal tear, the effect this has on chondral injuries to the knee also continues to increase, resulting in a higher risk of developing osteoarthritis.
Though there is a growing number of cases being treated with repair or augmentation, the majority of ACLs require reconstruction, which is rebuilding the ACL out of other tissue. Reconstruction options include using the patient’s own tissue called autograft or using donor tissue, which is called allograft. Among autograft tissue options are the patellar tendon, hamstring tendons, and quad tendon. The advantages of allograft include being able to predetermine the size of the graft as well as the absence of additional morbidity of graft harvest, the need to rehabilitate the area of graft harvest or the loss of function from the harvested tissue. The advantages of autograft include a higher success rate in terms of graft healing at all age ranges, especially in patients under the age of twenty, in addition to quicker graft incorporation time. While many surgeons, therapists, friends, or even family have their preferences, the decision as to which tissue to reconstruct the ACL should be based upon individual factors, including the risk tolerance for each individual graft.
Rehabilitation often begins prior to surgery given the swelling, loss of motion, bone bruising, limitations in weight bearing, and lack of strength. Following reconstruction, rehabilitation of the knee is quite critical. For a procedure that often takes an hour or less to complete, the timeline for return to the sport of injury is between six months and two years. Each phase is progressive, building upon the last phase, and is done in conjunction with the different phases of graft incorporation into the body. The first phase of rehabilitation involves treating the swelling, loss of motion, and quad dysfunction that comes from the surgery itself. Restoring the range of motion is a priority as it is not only a requirement for optimal pain control but for restoring something as simple as normal gait. The second phase involves regaining most strength and neuromuscular control. Most patients are initially shocked by the amount of quad atrophy experienced after ACL surgery and the accompanying loss of strength. A third phase involves a return to running, improving agility, and even developing proper mechanics of landing and other deceleration. As many if not most ACL injuries occur via a deceleration type injury, having the proper strength and motion is necessary to enter this phase, and the mastery of proper landing and pivoting techniques during this phase is obviously critical prior to returning to sport. The last phase is the return to sport. The variability in return to sport is often more due to factors outside the knee. Though the ACL reconstruction may be fully incorporated and strong at six months after surgery, especially for autografts, it is often the preinjury loss of strength, balance, coordination, mechanics, or the acquired deficiencies in these areas due to the injury that determine return to sport.