Single-Bundle Augmentation for Posterior Cruciate Ligament Reconstruction

Christopher A. Radkowski MD

Christopher D. Harner MD

History of the Technique

Posterior cruciate ligament (PCL) injuries are relatively infrequent occurrences that present a challenge to the orthopedic surgeon. Traditionally, nonsurgical treatment has been recommended for lower-grade isolated PCL ruptures, while some surgical results have shown persistent posterior laxity of the knee.¹^,²^,³^,⁴^,⁵^,⁶ However, other studies have shown degenerative changes and poor objective outcomes associated with conservative treatment of PCL injuries.⁷^,⁸^,⁹^,¹⁰^,¹¹ Advances in the understanding of the anatomy and biomechanics of the PCL have led to an increased interest in arthroscopic reconstruction of the PCL. Anatomic studies have delineated separate characteristics of the anterolateral (AL) and posteromedial (PM) bundles within the PCL.¹²^,¹³^,¹⁴^,¹⁵ The larger AL bundle has increased tension in flexion while the PM bundle has more tension in extension. The smaller meniscofemoral ligaments also contribute to the overall strength of the PCL.¹⁴

Other investigations have shown different biomechanical properties of the different PCL bundles, with the AL bundle possessing increased stiffness and ultimate strength.¹⁴^,¹⁶^,¹⁷ Single-bundle PCL reconstruction may not completely restore normal knee kinematics.¹⁸^,¹⁹^,²⁰^,²¹ Biomechanical and clinical studies revealed encouraging results with double-bundle PCL reconstruction.¹⁸^,¹⁹^,²²^,²³^,²⁴^,²⁵^,²⁶ Despite the increased understanding of the PCL and improving techniques for reconstruction, clinical results remain suboptimal and lag behind its ACL reconstruction counterpart.

Rationale

PCL reconstruction with augmentation of a single bundle offers advantages over other techniques in the treatment of PCL injuries. In addition to the intact AL or PM bundle, reconstruction of the injured bundle provides the equivalent of a double-bundle reconstruction, which has been shown to more closely restore normal knee laxity.¹⁴^,²⁶ Preservation of the intact native tissue can promote healing of the single bundle reconstruction. Magnetic resonance imaging (MRI) studies have demonstrated the capacity of the PCL to spontaneously heal and regain continuity.²⁷^,²⁸ In addition, some surgeons have favored preservation of native tissue as well. Wang et al.²⁹ recommend saving the PCL remnants and the surrounding synovium to benefit ligament reconstruction healing. Yoon et al.³⁰ describe their technique of preserving PCL remnant tissue during arthroscopic double-bundle augmentation of PCL with a split Achilles tendon allograft. We believe that although this technique can be time consuming and difficult, preservation of PCL tissue can provide enhanced posterior stability of the knee and promote graft healing. Preservation of the entire remnant PCL bundle is recommended by Ahn et al.²²^,³¹ for the same reasons.

Due to the reasons above and concerns over removing intact AL or PM bundle tissue in PCL reconstruction, the senior author (CDH) began single-bundle PCL augmentation with preservation of intact PCL tissue in 2000.

Indications and Contraindications

Single-bundle augmentation for PCL reconstruction is indicated in patients with an intact AL or PM bundle undergoing PCL reconstruction, usually for persistent posterior instability symptoms or a multiple ligament injury to the knee.

This technique is not recommended if there is complete rupture of both PCL bundles, although remnant tissue is preserved whenever possible. Single bundles with intact fibers
that appear lax upon arthroscopic evaluation are also preserved unless located directly at the insertion site of the target bundle.

Surgical Technique

Preoperative Assessment

A thorough history and physical examination are obtained preoperatively in a clinic setting. It is important to determine the chronicity of the injury. Note is made of the active range of motion (ROM) of both knees and any positive findings that may suggest associated pathology. An MRI is frequently obtained to determine the location of the PCL injury (Fig. 44-1) and to assess for meniscal pathology, which can be difficult to elucidate with a large effusion and a guarded physical examination. The lower extremity neurovascular examination is documented.

Anesthesia

The patient is identified in the preoperative holding area and the operative site is signed. The anesthesiology staff performs sciatic and femoral nerve blocks for postoperative pain management. The patient is taken to the operating room where spinal or general anesthesia is induced.

Patient Positioning

The patient is positioned supine on the operating room table. A padded bump is taped to the operating room table at the foot with the knee flexed to 90 degrees to hold the leg flexed during the case. A side post is placed on the operative side just distal to the greater trochanter to support the proximal leg with the knee in flexion. Padded cushions are placed under the nonoperative leg. A tourniquet is placed on the proximal thigh but is not routinely used.

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