Infection After ACL Reconstruction Remains Rare

All surgical procedures have some risks. Complications can vary from mild infection to something as serious as death. In this study, the risk of infection after anterior cruciate ligament (ACL) reconstructive surgery is calculated. Surgeons from the Hospital for Special Surgery in New York City present data from a review of over 3000 patients who had ACL surgery in their clinic.

This study helps put into perspective concerns about infection when using tendon grafts to replace the ruptured anterior cruciate ligament in the knee. There is always a niggling concern in the back of the surgeon’s mind about this problem.

Four main factors enter into the equation. There are two choices for graft tissue: taking the donor tissue directly from the patient (an autograft) or taking tissue from a donor bank (an allograft). Allografts have become increasingly popular with surgeons based on the fact that these are easy to use, come in a wide variety of sizes to choose from, decrease the time the patient is in surgery, and eliminate pain and problems at the donor site when patients use their own tissue.

But the question arises: is the risk of infection higher with donated tissue? And there are two types of graft collection sites: the hamstring tendon or the patellar tendon. The same question arises: is the risk of infection greater using one type over another?

The authors reviewed the charts of 3126 patients at their facility who had this type of surgery. They separated out these four variables and found that the overall incidence of infection is very low (less than one-half of one per cent). The rate of infection wasn’t any higher in the allograft (donor bank) tissue than for patients using their own tissue (autograft).

However, hamstring autografts do seem to have a higher risk of infection than patellar tendon grafts. This result has been reported by other researchers. There is some thought that the way in which the hamstring tendon grafts are sterilized might be the reason for an increased risk of infection with these grafts.

Even though this complication is rare, when it happens, it can still be devastating. The patient experiences fever, pain, and drainage with swelling and redness around the joint. The main danger is that the graft will have to be removed and the surgery done over. Surgeons do everything they can to save the graft and avoid a re-operation.

What can be done? Well, first the infection is confirmed by removing some fluid from the joint and testing it for bacteria. Staphylococcus aureus (staph infection) is the most common organism found. Then the joint is irrigated with a cleansing liquid called saline solution. The surgeon removes any infected tissue through a procedure called debridement. And finally, intravenous (IV) antibiotics are given for at least six weeks.

The process of irrigation and debridement may have to be repeated more than once. In this study, one-third of the patients needed this type of repeated surgery. That’s about average for what is reported in other studies of this kind. In the end, the authors were able to salvage (save) 72 per cent of the ACL grafts that got infected.

In summary, ACL graft infections are rare. Using allografts (donor tissue) doesn’t increase the risk of an infection. Most of the grafts can be saved with irrigation and debridement, though this treatment might have to be repeated more than once.

Hamstring autografts (taken from the patient) have the highest rate of infection probably due to the way the graft material is sterilized. The hamstring autograft were the least likely to be saved and kept intact. The authors suggest long-term studies now to see how well patients with graft infection and salvage procedures do over time (10 years or more).