Multiple Ligament Injury

Introduction

Multiligament injuries can pose challenging scenarios in terms of treatment protocols because of the complex nature of the injury mechanisms and potential complications that may occur. A knee dislocation is defined as an episode where at least two of the four major ligaments of the knee, being the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and/or the fibular/lateral collateral ligament (FCL/LCL), are injured. , , Although the reported prevalence of knee dislocations is low relative to reported knee injuries, earlier literature failed to account for occurrence of multiligament knee injuries presented in the reduced position. ^, For instance, the common peroneal nerve (CPN) has been reported to be damaged in 23% of traumatic knee dislocations, and this rate may be as high as 45% when the posterolateral corner (PLC) and posterior cruciate ligament (PCL) are among the injured ligaments involved in the dislocation.

To manage complex injuries and the respective complications, careful examination/execution upon each step of treatment should be conducted, beginning with imaging of the respective vascular region for possible damage, leading into taking precautions for intraoperative tunnel convergence, ^, and continuing to the use of postoperative protocols to avoid the development of arthrofibrosis or heterotopic ossification. ^, The following review will assess common complications that may occur in the preoperative, intraoperative, and postoperative phases of multiligament treatment, as well as how to best avoid and treat these complications upon occurrence.

Preoperative Issues

Complex knee injuries requiring multiligament reconstruction commonly occur following knee dislocations, and because of the severity of these injuries, serious damage may occur to neighboring structures and may even result in life-threatening conditions if safeguards are not taken upon patient presentation when admitted to the hospital/clinic. Therefore it is important to be aware of potential complications or technical difficulties and to be prepared to preemptively avoid many of them. In particular, it is important to recognize potential differences in high versus low or ultra-low velocity knee dislocations and the degree of potential systemic and neurovascular complications which may occur.

Vascular Injuries

Recent studies have also reported an incidence of vascular injury in high-velocity knee dislocations to range from 7.5% to 14%. ^{, ,} The popliteal artery is situated against the femur proximally by the adductor hiatus and distally against the tibia by the fibrous arch of the soleus muscle (shown in Fig. 19.1 ), placing it at an elevated risk to injury following the occurrence of knee dislocations. Major vascular injuries have been noted following knee dislocations in all directions, but the greatest occurrence has been reported in posterior knee dislocations. ^,

Injury can occur by complete arterial disruption, occlusive thrombus, or intimal tears. The simplest means for diagnosis can be achieved by checking the peripheral pulses, but imaging such as Doppler ultrasound may be necessary to either confirm or deny the presence of vascular injuries. In general, if the ankle-brachial index (ABI) is over 0.9, continued observation is generally indicated. If pulses are present but with an ABI of less than 0.9, a Doppler ultrasound should be performed. If pulses are absent, confirm the knee joint is reduced and consider referral to a vascular surgeon for immediate surgical exploration because an ischemia time over 8 hours has amputation rates as high as 86%. In addition, computer tomography angiography should be considered for presurgical planning of revision or chronic multiligament knee reconstruction, especially with injuries involving the PCL or a previous vascular repair. For those multiligament knee injured patients who present with a current deep vein thrombosis (DVT) and are on anticoagulant agents, referral may be made for placement of an inferior vena cava (IVC) filter before multiligament knee surgery, especially in patients with repairable meniscus tears (bucket handle, radial, root tears) and rather than discontinuing anticoagulant therapy.

Neurological Injuries

Ligaments of the knee are not the only focal point in acute high-velocity knee dislocations, because it has been commonly reported that neurological and vascular structures of the knee are quite vulnerable as well; this can be easily imagined upon reading the definition of an acute knee dislocation: complete disruption of the integrity of the tibiofemoral articulation. In cases of acute high-velocity knee dislocations, the CPN has been reported to be injured in 14% to 25% of cases ^{, ,} , and as high as 45% in cases where damage to the PLC and PCL has occurred, because of traction along the posterior aspect of the lateral femoral condyle.

The CPN is located in the posterolateral aspect of the knee ( Fig. 19.2 ). After its course around the fibular head it becomes two separate nerves: the lateral peroneal and deep peroneal nerves. The deep peroneal nerve supplies the inferior portion of the lateral capsule and the lateral collateral ligament from its origin at the joint line superior and posterior to the fibular head. The lateral peroneal nerve trifurcates around the fibular head and enters the joint at the anterolateral joint line through the substance of the peroneus longus muscle. The success of CPN regeneration following injury is dependent on the severity of the injury: crush injuries have been reported to have a less likely chance of a successful recovery relative to sharp injuries and severe dislocations.