Over the last two decades, single-bundle anterior cruciate ligament (ACL) reconstruction has largely been a successful operation.¹ Many patients over the short term have been able to return to sports with an improvement in subjective instability of their knee. However, recent studies have also found that a subset of patients experience persistent subjective knee instability and therefore are not able to return to prior activity.² Furthermore, long-term evaluation of patients suggests that osteoarthritic changes occur at the same rate as in knees that have not undergone surgery.^3,4 For example, a recent randomized controlled trial found radiographic degenerative changes in 84% of the subjects 11 years after ACL reconstruction.⁵ Results such as this, presented in many other papers,^3,4,6 have pushed the focus of ACL reconstruction toward an anatomic approach to more closely restore normal knee function and avoid long-term osteoarthritic changes.

Anatomic reconstruction of the ACL is defined as the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites.⁷ The aim of anatomic ACL reconstruction is to provide the patient with the greatest potential for a successful outcome. Four fundamental principles should be observed for achievement of this goal. The first is to carefully note the patient’s native anatomy. The second is to individualize each surgery with respect to the patient’s anatomy. The third is to place the tunnels and grafts in the center of the patient’s native footprints. The fourth is to reestablish knee biomechanics by tensioning the grafts to mimic the native ACL as closely as possible.⁸

The traditional anteromedial (AM)-based single-bundle ACL reconstruction was shown to successfully resist anteroposterior (AP) translation forces, but failed to correct rotational instability of the injured knee leading to abnormal knee kinematics.9,10 It is presumed that with this condition there is an altered wear pattern and subsequent premature evidence of osteoarthritis. Therefore, increasing efforts have been made during the past decade to restore normal knee kinematics. The “forgotten” posterolateral (PL) bundle, which plays an important role in both knee stability in extension and knee rotation in flexion, was found to be indispensable. Several studies have shown the clinical superiority of double-bundle (DB) reconstruction in restoring AP and rotational stability compared with the traditional single-bundle (SB) procedure.^11–17

The anatomic ACL DB concept views the ACL as two functionally different bundles that work synergistically. Hence the goal of the anatomic ACL reconstruction, which can be accomplished with an SB or a DB technique, is to restore the ACL anatomy as closely as possible and consequently to approximate normal knee kinematics. This chapter discusses the indications, contraindications, and surgical technique of anatomic SB and DB ACL reconstruction.

Preoperative Considerations

Patient Evaluation

A detailed history and careful physical examination are fundamental to diagnosis of an ACL injury. The mechanism of injury can support the diagnosis and also help discern if there are associated injuries. Certain symptoms are typically related to an ACL injury: an immediate knee effusion and pain along with initial difficulty in bearing weight. These symptoms tend to diminish over the weeks, and eventually the patient will be able to regain a complete range of motion. Sporadic pain and subjective instability of the knee are consistent with a more chronic lesion of the ACL. Clicking and popping in the knee associated with joint line tenderness indicate a simultaneous meniscal injury.

A physical examination should always be conducted on both legs for comparison. The examination includes observation of knee alignment while the patient is seated, standing, and walking and close examination for a joint effusion, muscular atrophy, and ecchymoses. Next, range of motion is assessed, followed by careful palpation of the knee joint to identify tender areas that may indicate concomitant injuries. In the acute setting it can be difficult to perform specific tests including the anterior drawer, posterior drawer, Lachman, pivot shift, reverse pivot shift, McMurray, dial, and varus and valgus stress tests. However, these tests are necessary for a complete knee evaluation and should be performed as soon as possible. In addition to standard physical examination tests, the KT1000 (MEDmetric, San Diego, CA) can quantify the degree of anterior laxity. A 3-mm or greater side-to-side difference suggests an ACL injury.

Imaging

A complete radiographic series including Merchant view for patellar evaluation, weight-bearing posteroanterior (PA) view in 45 degrees of flexion, lateral radiographs in 45 degrees of knee flexion, and full-extension AP radiographs is fundamental to the initial assessment of the injured knee. These films allow evaluation of degenerative changes, previous deformities, and associated fractures or avulsions.

High-quality magnetic resonance imaging (MRI) is used to help identify the rupture pattern of the ACL and associated injuries. Special sequences such as oblique coronal and oblique sagittal views enhance ACL visualization (Fig. 77-1A and B) by cutting MRI sections in the same anatomic alignment as the ACL. MRI also plays a definitive role in preoperative planning for individualized surgery. Measurements of the tibial insertion site, ACL length, ACL inclination angle, and quadriceps and patellar tendon thickness on sagittal view are routinely employed to help determine reconstruction technique and graft choice (Fig. 77-1C to F). For example, DB reconstruction is indicated if the tibial insertion site measures more than 18 mm. An insertion site size less than 14 mm does not easily permit the drilling of two separate tunnels while a 2-mm bone bridge is maintained between them. In this scenario, an SB reconstruction would be the better option.^18–20 In insertion sites between 14 and 18 mm, either an SB or a DB procedure can be performed.