Technical Considerations in Revision Anterior Cruciate Ligament (ACL) Reconstruction for Operative Techniques in Orthopaedics

Abstract

As the incidence of anterior cruciate ligament (ACL) reconstruction continues to increase, the rate of revision surgery continues to climb. Revision surgery has inherent challenges that must be addressed in order to achieve successful results. The cause of the primary ACL reconstruction failure should be determined, and careful preoperative planning should be performed to address the cause(s) of failure. Each patient undergoing revision surgery should undergo a thorough history and physical examination, receive full length alignment radiographs, lateral radiographs, 45-degree flexion weight-bearing postero-anterior radiographs, and patellofemoral radiographs. 3-dimensional computed topography (CT) scan should be performed to assess tunnel position and widening. Magnetic resonance imaging (MRI) should be used to assess for intra-articular soft tissue pathology. Meniscal tears, meniscal deficiency, anterolateral capsule injuries, bony morphology, age, activity level, connective tissue diseases, infection, graft choice, and tunnel position can all impact the success of ACL reconstruction surgery. Meniscal lesions should be repaired, and in cases of persistent rotatory instability, extra-articular procedures may be indicated. Furthermore, osteotomies may be needed to correct malalignment or excess posterior tibial slope. Depending on the placement and condition of the original femoral and tibial tunnels, revision surgery may be performed in a single procedure or in a staged manner. In most cases, the surgery can be performed in one procedure. Regardless, the surgeon must communicate with the patient openly regarding the implications of revision ACL surgery and the treatment plan should be developed in a shared fashion between the surgeon and the patient.

Figure 1. Quantitative Pivot Shift Measurement

An iPad Screenshot demonstrates a graphical representation of a quantitative pivot shift measurement. Surface markers (not shown) are placed on the lateral femoral epicondyle, Gerdy’s tubercle, and the fibular head. The iPad video camera then records the pivot shift maneuver and calculates the lateral compartment translation. The 4.027mm distance displaced in this figure is then multiplied by a factor of 3 (surface markers on the skin translate 3 times less during pivot shift than the actual bone) for a total of 12.081mm of lateral tibial translation.

Figure 2. 3-Dimensional CT Scan for Tunnel Assessment

A 3D CT scan demonstrates the primary reconstruction tibial (A) and femoral tunnels (B). An asterisk indicates the center of the actual ACL footprint, and the goal location of the new tunnels. In this case, the previous tunnels have been placed in a non-antomic position, and the revision can be performed utilizing completely new tunnels, with little risk of convergence of the pre-existing tunnels.

Figure 3. Algorithm for Staging of Revision ACL Reconstruction

When revising a previous ACL reconstruction which utilized anatomic tunnel positions, a primary single stage surgery can be performed if there is no excessive tunnel widening. If there is tunnel widening >16mm, a staged procedure with bone grafting can be performed, a graft with a large bone block can be utilized, or the femoral fixation can be performed using the over-the-top technique. Similarly, if the tunnels are in a semi-anatomic position, alternative options may be indicated if tunnel widening is present. If the tunnels are in a completely non-anatomic position, revision surgery can often be performed utilizing completely new tunnels.

Figure 4. Magnetic Resonance Imaging Demonstrating Meniscal Insufficiency

T2 magnetic resonance imaging (MRI) demonstrating significant medial meniscal deficiency. An asterisk is placed near the diminutive meniscus in the coronal (A) and sagittal (B) cuts. In the case of extreme meniscal deficiency, the meniscal allograft may be indicated in a an active patient with minimal arthritic changes.

Figure 5. Technique for Measurement of Tibial Slope

Sagittal 1-Tesla magnetic resonance imaging (MRI) demonstrating the technique to measure posterior tibial slope. A) A line is drawn going through the center of concentric circles to localize the anatomic axis of the tibia. B) The angle between the anatomic tibial axis and the articular surface is measured to provide posterior tibial slope.