There are certain circumstances where it is inappropriate to attempt revision ACL surgery.

ACL revision should not be undertaken in patients with:

Partial function in a prior ACL reconstruction

Patients who have had a prior ACL reconstruction in which partial function remains are not candidates for revision surgery. Partial function is defined as either an increase of 3 to 5 millimeters of anterior tibial translation (tibia can be pulled forward this amount) compared to the opposite, normal knee, or a grade 1 "soft" pivot-shift test in which a definite endpoint is detected. In these knees, careful yearly examinations are recommended to monitor the joint for any signs of complete failure of the graft or arthritic deterioration. If a patient with partial function of a prior reconstruction sustains a new knee injury, then immediate consultation should be undertaken to assess the integrity of the graft. If the graft has indeed completely failed, then revision should be considered as soon as possible if the patient is athletically active or has an occupation that places great demands on the knee joint.

No symptoms (pain, swelling, giving way) in a patient who does not participate in strenuous or high risk activities

Patients with a failed ACL reconstruction who decide not to participate in activities considered "high risk" for further injuries, and who do not experience symptoms such as pain, swelling, or giving-way, do not require revision reconstruction. High risk activities include any sports or occupations that involve turning, twisting, pivoting, cutting, and jumping. The conservative treatment program for these patients is similar to that prescribed for ACL-deficient patients who decide not to undergo any surgery. This includes maintenance of adequate muscle strength and fitness levels, periodic evaluations, and education regarding avoidance of any activity which could result in a reinjury.

Prior joint infection

Patients who had a prior joint infection with subsequent joint deterioration are usually not candidates for ACL revision reconstruction. This is because the joint deterioration is usually extensive and will not be improved by the revision procedure - in fact, the knee joint could be made worse if a postoperative complication occurs.

Obesity (body mass index >30)

Patients with a body mass index greater than 30 are not considered candidates for this operation until weight loss has occurred and the index is brought below 30. The forces placed on the ACL graft are too great with increased body weight and there would be a high expectation for subsequent graft failure. Patients with this problem are counselled and referred if required to a managed weight loss treatment centre.

Bowed legs where the patient refuses to undergo a high tibial osteotomy before or with the ACL revision reconstruction

Because a bowed leg (termed varus malalignment) causes abnormally high forces on an ACL graft and is a common cause of failure of this operation, this problem must be solved either before or during an ACL revision reconstruction. If the bowed leg is not corrected, the revision graft will have an unacceptably high risk of failure. We have seen many unfortunate patients in our Centre over the last 3 decades in whom this problem existed and was not solved - some of these individuals underwent 2 or even 3 ACL reconstructions, all of which failed. The bowed leg problem is corrected with an operation called a high tibial osteotomy. In some patients, the osteotomy and subsequent rehabilitation provides enough stability that an ACL revision is not required. That is why we prefer to stage these procedures - perform the osteotomy first, rehabilitate the knee for at least 4 to 6 months, and then discuss the necessity for the ACL revision procedure.

Severe muscle atrophy (wasting)

Patients with a prior failed ACL reconstruction who have severe muscle atrophy and weakness must first undergo a program of rehabilitation to regain normal muscle strength before consideration is given for the revision procedure. Typically, several months are required to restore adequate strength. Otherwise, these patients have an increased risk for serious postoperative complications including quadriceps muscle shutdown, patella infera, and arthrofibrosis. In some cases, the restoration of muscle function may lead to better knee stability, and the ACL revision is not required.

Poor patient motivation or expectations

Patients with poor motivation and in whom the clinician believes will not comply with the postoperative rehabilitation program are not considered candidates for ACL revision.

It is important that the patient understands the realistic outcomes of a revision reconstruction, which usually are not the same as a primary reconstruction. This is because most revision knees have pre-existing joint damage (arthritis) and partial or total loss of meniscus function. Others have problems with other knee ligaments, or require staged procedures to correct bowed legs or to fill in misplaced tunnels with bone grafts. 

Many patients that have joint stability restored following their revision reconstruction believe their pre-injury athletic activities may be possible without modification. This is ill-advised, as the joint damage will only worsen if high-impact activities are resumed after surgery. The goal is to allow an active lifestyle, using mostly low-impact activities such as bicycling, swimming, low-impact aerobics, to keep fit and healthy.

Knee arthrofibrosis

Patients with pre-existing and permanent arthrofibrosis, or a severe limitation of knee motion, are not candidates for ACL revision reconstruction. This is because the revision reconstruction would not be expected to improve the arthrofibrotic condition, and may in fact worsen the problem.

Deficiency of the posterolateral structures where the patient refuses to undergo an associated posterolateral reconstruction with the ACL revision

Deficiency of the lateral collateral ligament and other posterolateral structures of the knee causes abnormally high forces on an ACL graft and has been noted to be a cause of failure of this operation. A patient with this associated problem must be willing to undergo a combined posterolateral ligament - ACL revision reconstruction. To ignore the posterolateral ligament deficiency carries a high risk of failure of the ACL revision graft - too high, in my opinion, to accept. There are now graft reconstructive procedures for the LCL and posterolateral structures which have a very good success rate. In our Centre, patients who undergo this combined operation begin rehabilitation the 1st day after surgery and are allowed to move their knee, do basic muscle exercises, and bear part of their body weight using crutches.

Symptomatic Arthritis

The presence of symptomatic arthritis is a general contraindication to ACL revision surgery, as the pain symptoms will not be solved by this operation. Although pain symptoms  may be lessened by restoring knee stability, the arthritis will still limit daily activities. Weight bearing 45° posteroanterior X-rays are important to obtain to measure the millimeters of remaining joint space. Patients in whom the joint space is absent or nearly absent are treated with conservative measures until such time that partial or total joint replacement is warranted.

Complex Regional Pain Syndrome

The presence of residual signs and symptoms of a complex regional pain syndrome (CRPS), also called Reflex Sympathetic Dystrophy, requires careful examination and questioning regarding the presence of burning pain, abnormal skin hypersensitivity, extremity discoloration, and intolerance to cold and ice. Patients with active, or "quiet" CRPS/RSD usually are not considered candidates for ACL revision reconstruction. This is because that, even after resolution of the CRPS/RSD, there is an increased frequency for return of the syndrome after knee surgery.