Anterior cruciate ligament (ACL) reconstruction is the most common type of surgery for a completely torn acutely or chronic insufficient ACL with associated instability. ACL-deficient knees are at marked risk for developing meniscal injury. The loss of meniscal tissue is associated with degeneration. On the other hand, an isolated ACL tear without meniscal or chondral injury may not predispose to arthritis. It is rare to be able to repair the torn ACL by simply reconnecting the torn ends.
However, in very specific injuries when the ACL is detached from the femoral attachment site (such as in certain types of skiing accidents), it may be possible to perform a primary repair. Nevertheless, the mainstay of ACL tear management is reconstruction. Most surgeons now favor reconstruction of the ACL using a piece of tendon to replace the torn ACL.
Successful ACL reconstruction is dependent on a number of factors, including surgical technique, post-operative rehabilitation and associated secondary ligament instability. Today, ACL reconstruction is usually performed with arthroscopic assistance. The surgeon uses a graft, to replace the torn ACL. The graft may be taken from elsewhere in the patient's extremity (autograft), harvested from a cadaver (allograft) or may be synthetic.
Read Frequently Asked Questions about ACL injury and repair here.
Autograft is the most widely performed orthopedic ACL reconstruction. The technique involves moving (harvesting) the patient’s own tissue. Commonly used autografts are the mid-third of the patellar tendon with bone attached at both ends, one or two medial hamstrings, or the quadriceps tendon with bone at one end. Results are somewhat similar and secondary effects are unique to the harvest site. Surgeon preference is the primary factor in selection.
Your surgeon, however, is limited by the amount of tissue he can remove. A possible effect in some patients undergoing an autograft is that the donor site may be painful after surgery. In the light of this pain, in certain circumstances surgeons may consider other donor tissue – allograft or a synthetics.
An allograft is tissue that is harvested from a cadaver. (Donor tissue is kept at a tissue bank where it is screened for infection and then stored-most commonly frozen.) The advantage of using an allograft is obvious. The patient's own tissue is not disturbed and thus there is no harvest site morbidity. The operation also takes less time because harvesting time is deleted. The typical candidate for allograft ACL reconstruction is an active person whose has ACL deficient instability or at risk for instability who wishes to avoid graft harvest site pain. Often, these are busy individuals with an active family and work life, who desire the potential earlier return to work than an autograft.
The advantages of synthetic grafts are the lack of harvest site morbidity, off the shelf availability, and no disease transmission. However, the failure rates of synthetic grafts tested in the USA were unacceptable. Synthetic grafts currently have inherent mechanical properties that do not closely resemble the normal ligament and as they are not living, they cannot repair themselves, as can natural ligaments. Work on an acceptable synthetic ligament continues in the USA and implantation is still performed outside the USA.
Orthopedic surgeon (Often Knee and/or Sports Medicine Subspecialty)
ACL reconstruction is usually not performed until a few weeks after the injury. Studies have shown improved results when the knee has recovered from the acute injury response. At this time, swelling and pain have decreased and the patient has regained near full motion and strength.
Before the procedure:
- The doctor will perform a standard knee exam and discuss with the patient the pros and cons of operative and non-operative management.
- The doctor will discuss the surgery including ACL graft options, the risks and complications and achieve fully informed consent.
During the procedure:
The patient is anesthetized using general, spinal/epidural, regional or in some centers, local anesthetic with sedation. Arthroscopy allows determination of associated injuries, which are usually treated at the same setting (e.g., meniscal tears or chondral trauma). The space in the knee where the PCL and ACL reside, the notch, is often narrow and in those cases it is widened (notchplasty) to accommodate the graft.
Then through a small separate accessory incision, a tunnel is drilled through the tibia (lower leg bone) and through the femur (the upper bone) in the same position as the original ligament attachment sites. The graft is fashioned to fit into these tunnels. The graft is fixed to the femur and tibia (upper and lower leg bones) by a variety of means. Once secure, the graft is checked for proper tension. The knee is placed in a compressive dressing with allowance for cryotherapy. Usually the patient is released as an outpatient.
While resting during the first 3 or 4 days, efforts are directed at minimizing the swelling and reestablishing quadriceps function. During this time cryotherapy and elevation of the knee, leg and ankle are emphasized. Moving frequently increases blood flow return from the extremity (e.g. ankle pumps).
- Crutches are used to walk bearing weight as per doctor's orders. The emphasis is on a normal gait without limping.
- Wear comfortable shoes.
- Stay within your safe range of motion as directed by your doctor.
- Bathe and shower after surgery as your surgeon directs.
Most surgeries are being done on an outpatient basis, although some patients stay overnight. After surgery, you will begin a rehabilitation program. The patient alone may do rehabilitation, with a certified athletic trainer or with a physical therapist. Formal therapy usually last 2-12 weeks and then is followed by a “home program” which will last until full strength and agility are achieved which usually takes four to six months. Following the rehabilitation, you may be placed on a return to sport program using a functional progression approach.
The course after allograft is the same as autograft except that patients often experience less pain in the first week or two allowing an earlier return to light duty work or school.
- Graft failure due to re-injury, graft specific factors, tunnel placement, tensioning, or fixation methods
- Blood clots (very rare)
- Surgical wound infection
- Risk of developing arthritis
- Weakening of muscles
- Lack of full range of motion
Prescription and non-prescription pain relievers.
See Your Doctor If:
- Pain, swelling, redness, drainage or bleeding increases in the knee.
- You experience any symptoms suggestive of infection or concerns of a blood clot.
Last updated: 24-Jan-06