It is estimated that more than 200,000 ACL injuries occur on an annual basis. Many of these are the direct result of sports related activities. Sudden stopping, twisting, or change in direction with the leg raises the risk for an ACL tear.
The purpose of the ACL is to provide rotational stability of knee. While not all ACL tears require surgery, many of these tears occur in combination with meniscal tears and other ligament tears that lead to instability and loss of function. Indications for surgery include combined injuries of the ACL and other supporting structures, a full tear that results in instability, and for those who participate in high demand activities or sports. The goal of surgery is to have a stable knee, restore functional ability, and return back to full activity.
Surgery for an ACL tear can often be performed arthroscopically by a highly trained orthopaedic surgeon who specializes in this type of procedure. The torn ligament is remove and replaced with a graft. The graft can be an autograft (from the patient) or from an allograft (cadaver). Common autografts include the patellar tendon (“gold standard”), quadriceps tendon and hamstrings tendon. Allografts reduce donor site morbidity but have the disadvantages of availability, cost, potential risk of bacterial infection, and graft failure. Traditionally, graft choice is made based on age and lifestyle. The graft is placed once a tunnel is drilled into the bone. The graft is secured with screws or other fixation devices.
This type of surgery can be performed on an outpatient basis. General or regional anesthesia (numbing below the waist) is commonly use.
Post-operatively, patients are placed into a knee immobilizer following surgery. Depending on the surgeons recommended rehabilitation protocol, early motion with the use of a continuous passive motion (CPM) machine is started the day of surgery. Weight-bearing with crutches is recommended for the first few weeks to protect the repair. A structured rehabilitation program is aimed at restoring motion, stability, and strengthening following surgery. This may take 4 to 6 months, or longer in some cases for full recovery.
Complications from this type of surgery are not that common. Some of the potential risks include infection, nerve and blood vessel injuries, delayed graft healing/failure, instability, bleeding and blood clots. There are also specific risks associated with anesthesia. Adherence to the rehabilitation protocol is important for a successful outcome.