Repeat revision ACL reconstruction presents unique challenges to the orthopaedic surgeon. Patient needs and expectations must be balanced with the risks, potential complications, and the guarded prognosis associated with the multi-operated knee. Consideration must be given to the patient’s chief complaint and the specific goals of the surgical procedures. As stated previously, most patients will present complaining of recurrent instability, pain, stiffness, or some combination thereof. The available revision ACL literature suggests that the greatest chance for a positive outcome results from revision surgery performed for recurrent instability [7–15]. An anatomically placed and appropriately tensioned graft in a patient who has participated in a focused rehabilitation program will reliably restore translational and rotational stability. However, it is important to note that the correlation between objective laxity and subjective outcomes is not linear [7, 15] and the problems associated with pain and stiffness may not be solved by a revision ligament reconstruction. When pain is the chief patient concern and the preoperative evaluation uncovers extensive meniscal or chondral pathology, revision surgery should be discouraged despite the presence of objective laxity. Conversely, if pain is associated with recurrent giving-way episodes and no other significant cause is identified, revision reconstruction may be entertained. Likewise, unless graft placement is nonanatomic, loss of motion should be addressed by physiotherapy or non-reconstructive surgery such as arthroscopic debridement.

The two most important questions to answer when planning for revision ACL surgery are: (1) is there a need for concomitant procedures? and (2) should these procedures be staged? Associated instability patterns resulting from collateral ligament and/or PCL deficiencies may need to be addressed at the time of the revision ACL reconstruction. Likewise, malalignment correction with an osteotomy may also be required. Meniscal and articular cartilage procedures should also be incorporated into the operative plan. The need for staging is dependent upon the presence of massive tunnel expansion and/or malposition that precludes proper tunnel placement without bone grafting prior to revision surgery. The most common scenario is a femoral tunnel that was placed too anterior, too vertical, or a combination of both. This can be addressed in the vast majority of cases by either drilling an entirely new femoral tunnel or creating a blended tunnel (with or without bone grafting). Another option is to utilize the existing femoral tunnel while adding a second femoral tunnel in order to employ a double-bundle reconstruction in an attempt to improve rotational stability.

Other important factors to consider before surgery include the source of the previous graft, as well as the type and location of hardware. Revision ACL reconstruction graft options depend on which grafts were used in the previous surgical procedures. These options include autograft (ipsilateral or contralateral patellar tendon, hamstring, and quadriceps tendons) and allograft (patellar, Achilles, tibialis anterior, quadriceps tendons). We consider autograft tissue if the prior procedure utilized allograft and prefer allograft tissue if the prior procedures utilized autograft. Allograft has the advantages of no donor site morbidity and decreased operative time. Additionally, allogeneic tissue with bone blocks also allows for filling of the preexisting bone tunnels.

The patient is placed supine on the operating table. A spinal anesthetic or a general anesthetic is administered in addition to a femoral nerve block. Routine prophylactic antibiotics are given intravenously. The patient is positioned on the table to allow for maximal knee flexion during surgery and a lateral post helps facilitate valgus stress.

A thorough examination of both knees is performed under anesthesia before prepping the leg. It is important to assess the integrity of the ACL as well as the collateral ligaments, PCL, and posterolateral corner by varus/valgus stress testing in full extension and 30° of flexion, the posterior sag and drawer tests, and posterolateral drawer and dial tests (external rotation at 30 and 90° of flexion).

After sterile prep and drape, a standard diagnostic knee arthroscopy is performed to assess the previous ACL graft, menisci, articular cartilage, and PCL. Remnants of the previous graft are removed, the posterior and distal margins on the medial wall of the lateral femoral condyle are identified and a notchplasty is performed if necessary to prevent graft impingement. The notchplasty may also help to facilitate removal of existing hardware if necessary and to aid in the placement of new tunnels if needed. The previous tibial tunnel entrance is identified and the hardware is removed if necessary. If the tunnel location is acceptable, a guidewire is placed through the existing tibial tunnel. Based on preoperative evaluation of imaging and the intra-operative findings, decisions are made on tunnel position and diameter, the need for bone grafting, and the type of fixation to be used.

While most revision ACL reconstructions can be performed with bone grafting as necessary at the time of the revision operation, massive tunnel expansion (16 mm or greater) may require a two-stage approach with hardware removal and bone grafting performed as the initial procedure (see Fig. 24.1a, b). Femoral tunnel malposition may also necessitate a two-stage revision if previous tunnel placement interferes with the placement of the new tunnel. Other required procedures such as osteotomy, articular cartilage, or meniscal surgery can also be completed during this first stage. Revision ACL reconstruction is then performed after the bone graft is incorporated, typically 6–9 months later (see Fig. 24.2a, b).

After all hardware and soft tissue remnants have been removed from the femoral and tibial tunnels, a guidewire is placed in each tunnel to allow compaction reaming. If necessary, tunnels can be grafted with cancellous autograft or allograft, bone dowels, or bone substitutes. When grafting the tibial tunnel, an instrument should be used to cover the tunnel exit site in the joint with graft placed through the entrance site on the anterior tibia. Graft can then be packed against the instrument using a bone tamp.