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Multiligament knee reconstruction: Avoiding tunnel convergence and optimal graft fixation order


OVERVIEW

Chapter synopsis

When reconstructing several knee ligaments, there is an increased risk of reconstruction tunnel convergence on both the tibia and femur; therefore, planning tunnel position and orientation is crucial. Tunnel convergence can compromise ligament reconstructions and fixation, ultimately leading to reconstruction graft failure. The ligament tensioning sequence influences the final tibiofemoral orientation and knee kinematics.

Important points

  • A comprehensive physical exam, stress x-rays, and MRI are key to fully diagnose associated lesions.

  • Surgical management is recommended for most multiligamentary knee injuries (MLKIs) in order to restore knee kinematics and function.

  • These lesions should be treated in the acute setting whenever possible; however, surgical management should be delayed in cases of soft tissue compromise or vascular injuries.

  • Ligament reconstruction has superior outcomes to repair.

  • Good surgical planning to avoid tunnel convergence is important.

  • Proper ligament reconstruction sequence is recommended in order to restore knee kinematics.

Clinical/surgical pearls

  • If feasible, address all the pathology during a single surgery.

  • In chronic cases, assess the limb alignment so it can be addressed prior to or concurrent with the reconstruction to prevent graft failure

  • An open posterolateral and/or posteromedial surgical approach is performed prior to arthroscopy to allow for improved soft tissue visualization and to limit fluid extravasation into the surgical site.

  • Identify and mark ligament attachment footprints for tunnel placement.

  • Plan tunnel length and diameter to minimize the risk of convergence and failure.

  • Ream sockets and tunnels for cruciate ligaments first because it is easier to change tunnel orientation for collateral ligaments than cruciate ligaments.

  • Place guide-pins for collateral ligaments and visualize with an arthroscope to ensure no tunnel convergence.

  • Consider using a C-arm after guide-pin placement and before reaming.

  • Aiming the superficial medial collateral ligament (sMCL) tunnel 40 degrees anteriorly and 20 to 40 degrees proximally, and the posterior oblique ligament (POL) tunnel 20 degrees anteriorly and proximally minimizes the risk of tunnel convergence.

  • A 35- to 40-degree angulation in the axial plane and 0 degrees in the coronal plane (35 to 40 degrees anteriorly) for fibular collateral ligament (FCL) and popliteus femoral tunnels is safe, and avoids tunnel convergence.

  • Ream all tunnels (sockets) before passing grafts.

  • Leaving passing sutures after drilling each tunnel facilitates later graft passage.

  • Recommended graft tensioning sequence: posterior cruciate ligament (PCL), anterior cruciate ligament (ACL), FCL, Popliteus, and MCL.

Clinical/surgical pitfalls

  • Non-anatomic placement of the tunnels (sockets) can jeopardize the reconstruction; thus, only ream the tunnels after verifying that the guide-pins are in the correct position.

  • Tunnel convergence can damage graft and fixation leading to failure.

  • Passing grafts before reaming all tunnels can make visualization difficult and increases the risk of graft or fixation damage.

  • Tensioning and fixing the collaterals first increases the risk of rotating the tibia and altering knee kinematics and loading.

  • Tensioning the ACL first subluxates the tibia posteriorly.

  • A brace to protect the grafts and allow early ROM should be utilized after surgery.

  • Early rehabilitation is important to regain function and minimize the risk of joint stiffness.

Introduction

A multiligament knee injury (MLKI) is commonly defined as a high-grade tear of at least two of the four major knee ligament complexes: the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the posterolateral corner (PLC), and the posteromedial corner (PMC). , These injuries are challenging to treat because of the complexity, concomitant injuries, and challenges with postoperative rehabilitation. A high level of suspicion, and a thorough and systematic evaluation, is imperative to avoid missing the diagnosis. This is particularly important because missed and untreated concomitant injuries, including ligament, chondral, and meniscal lesions, can lead to inferior patient outcomes and an increased risk of failure of ligament reconstructions. Early diagnosis and treatment of all injured structures are recommended in order to restore knee anatomy and biomechanics. Furthermore, early surgery will allow for early rehabilitation in order to reduce the risk of joint stiffness, which is high in these injuries. When reconstructing several ligaments in multiligament injured knees, there are certain challenges the surgeon should be aware of in order to optimize the reconstruction and minimize the risk of graft failure. This includes the high risk of tunnel convergence and the graft tensioning sequence that can influence the tibiofemoral orientation and hence knee kinematics. In this chapter, we will discuss technical tips on avoiding reconstruction tunnel convergence and the reconstruction graft fixation sequence during multiligament reconstructions.

Epidemiology and concomitant injuries

Multiligament knee injuries (MLKIs) are not as rare as previously reported. Historically, studies reported on MLKIs caused by knee dislocation; however, with the advent of magnetic resonance imaging (MRI) and increased awareness, more MLKIs that are not associated with knee dislocation have been reported. Some recent studies have reported that 44% to 47% of MLKIs were caused by sporting injuries , ; therefore, it is important to be aware of the possibility of these complex knee injuries, despite apparent low energy. The morbidly obese are at risk of sustaining ultra-low velocity MLKI with a high risk of neurovascular injury and postoperative complications.

The medial side is the most commonly injured side of the knee, and up to 78% of high-grade (grade III) MCL injuries have an associated lesion, especially cruciate ligament and/or meniscus injuries. , Geeslin et al. reported that only about 28% of PLC knee injuries were isolated injuries, suggesting that most PLC injuries occur as part of an MLKI. Moatshe et al. found that injuries with three ligaments torn (KD III) were the most common, with medial-sided injuries (KD III-M) constituting 52.4% and lateral-sided injuries (KD III-L) 28.1%, when evaluating 303 patients with knee dislocations.

Concomitant meniscal injuries in conjunction with a MLKI have been reported in 37% to 55%, while the incidence of a concomitant cartilage injury is 28% to 30%. , The incidence of injury to the peroneal nerve in patients with knee dislocations has been reported to range from 19% to 40%, while the rate of popliteal artery injury has been reported to range between 7% and 48%. In a systematic review, Medina et al. reported a frequency of 25% and 18% for nerve and vascular injuries respectively. Moatshe et al. found that patients who had a PLC injury had 42 times greater odds of experiencing a peroneal nerve injury and 9.2 times greater odds of experiencing a popliteal artery injury than patients without a PLC injury. Furthermore, patients with peroneal nerve injury had 20 times greater odds of experiencing a concomitant vascular injury. Together, these studies highlight the importance of evaluating for concomitant neurovascular injuries in patients with MLKI.

Preoperative considerations

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