Surgical Intervention and Considerations

Patients treated with surgical reconstruction of the ACL have long-term success rates of 82 percent to 95 percent. Recurrent instability and graft failure are seen in approximately 8 percent of patients. The goal of the ACL reconstruction surgery is to prevent instability and restore the function of the torn ligament, creating a stable knee. This allows the patient to return to sports. There are certain factors that the patient must consider when deciding for or against ACL surgery.

Patient considerations

Active patients involved in sports or jobs that require pivoting, turning or hard-cutting as well as heavy manual work are encouraged to consider surgical treatment. This includes older patients who have previously been excluded from consideration for ACL surgery. Activity, not age, should determine if surgical intervention should be considered.

In young children or adolescents with ACL tears, early ACL reconstruction creates a possible risk of growth plate injury, leading to bone growth problems. The surgeon can delay ACL surgery until the child is closer to skeletal maturity or the surgeon may modify the ACL surgery technique to decrease the risk of growth plate injury.

A patient with a torn ACL and significant functional instability has a high risk of developing secondary knee damage and should therefore consider ACL reconstruction.

It is common to see ACL injuries combined with damage to the menisci (50 percent), articular cartilage (30 percent), collateral ligaments (30 percent), joint capsule, or a combination of the above. The “unhappy triad”, frequently seen in football players and skiers, consists of injuries to the ACL, the MCL and the medial meniscus. In cases of combined injuries, surgical treatment may be warranted and generally produces better outcomes. As many as 50 percent of meniscus tears may be repairable and may heal better if the repair is done in combination with the ACL reconstruction.

Surgical choices

The middle third of the patellar tendon of the patient, along with a bone plug from the shin and the knee cap is used in the patellar tendon autograft . Occasionally referred to by some surgeons as the “gold standard” for ACL reconstruction, it is often recommended for high-demand athletes and patients whose jobs do not require a significant amount of kneeling. In studies comparing outcomes of patellar tendon and hamstring autograft ACL reconstruction, the rate of graft failure was lower in the patellar tendon group (1.9 percent versus 4.9 percent). In addition, most studies show equal or better outcomes in terms of postoperative tests for knee laxity (Lachman’s, anterior drawer and instrumented tests) when this graft is compared to others. However, patellar tendon autografts have a greater incidence of postoperative patellofemoral pain (pain behind the kneecap) complaints and other problems. The pitfalls of the patellar tendon autograft are:

• Postoperative pain behind the kneecap
• Pain with kneeling
• Slightly increased risk of postoperative stiffness
• Low risk of patella fracture

The semitendinosus hamstring tendon on the inner side of the knee is used in creating the hamstring tendon autograft for ACL Reconstruction. Some surgeons use an additional tendon, the gracilis, which is attached below the knee in the same area. This creates a two- or four-strand tendon graft (Figure 8). Hamstring graft proponents claim there are fewer problems associated with harvesting of the graft compared to the patellar tendon autograft including:

• Fewer problems with anterior knee pain or kneecap pain after surgery
• Less postoperative stiffness problems
• Smaller incision
• Faster recovery

The graft function may be limited by the strength and type of fixation in the bone tunnels, as the graft does not have bone plugs. There have been conflicting results in research studies as to whether hamstring grafts are slightly more susceptible to graft elongation (stretching), which may lead to increased laxity during objective testing. Recently, some studies have demonstrated decreased hamstring strength in patients after surgery.

The quadriceps tendon autograft is often used for patients who have already failed ACL reconstruction. The middle third of the patient’s quadriceps tendon and a bone plug from the upper end of the knee cap are used. This yields a larger graft for taller and heavier patients. Because there is a bone plug on one side only, the fixation is not as solid as for the patellar tendon graft. There is a high association with postoperative anterior knee pain and a low risk of patella fracture. Patients may find the incision is not cosmetically appealing.

Allografts are grafts taken from cadavers (Figure 10) and are becoming increasingly popular. These grafts are also used for patients who have failed ACL reconstruction before and in surgery to repair or reconstruct more than one knee ligament. Advantages of using allograft tissue include elimination of pain caused by obtaining the graft from the patient, decreased surgery time and smaller incisions. The patellar tendon allograft allows for strong bony fixation in the tibial and femoral bone tunnels with screws. However, allografts are associated with a risk of viral transmission, including HIV and Hepatitis C, despite careful screening and processing. Several deaths linked to bacterial infection from allograft tissue (due to improper procurement and sterilization techniques) have led to improvements in allograft tissue testing and processing techniques. There have also been conflicting results in research studies as to whether allografts are slightly more susceptible to graft elongation (stretching), which may lead to increased laxity during testing.