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.
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.
Timing of Surgery
The timing of surgery may be a controversial topic for the surgical management of multiligament injured knees. In general, acute surgery is desired for most multiligament knee injuries. However, in cases of other potential life-threatening injuries, significant stiffness, or surrounding soft tissue injury, a delay in surgery may be required. Acute management (<3 weeks from injury) is generally advocated by most authors because scarring of the tissue has yet to occur and tissues may have sufficient integrity for reapproximation and suture placement, especially when dealing with lateral-sided injuries; whereas delay of surgery is favored by some authors to allow for capsular sealing and subsidence of soft tissue swelling. Levy et al. performed a review of the literature to find the most optimal choice. They reported that most studies reported greater improvement in functional and clinical outcomes in cases receiving early treatment, although some studies suggested the avoidance of acute management owing to the higher incidence of arthrofibrosis; study results specific to arthrofibrosis were heavily weighted on the rehabilitation protocol administered to each patient.
In addition, the severity of injury, including knee dislocations and the use of external fixators, may contribute to the risk of developing arthrofibrosis. Although some studies have reported high rates of return to activity and relatively high proportions of excellent outcomes at 2-year and 3-year follow-up, in a comparison study, late (>4 weeks) surgical treatment of multiligament injuries reported significantly lower scores for International Knee Documentation Committee (IKDC), Noyes, and activity relative to early (<4 weeks) treatment. Levy et al. therefore concluded that acute management of multiligament injuries yields superior outcomes as opposed to delayed surgical management. Thus delayed surgery and the use of external fixators in those with knee dislocations should be avoided at all costs if possible when treating patients with multiligament knee 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.
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.
Deep Vein Thrombosis/Pulmonary Embolism
Multiligament knee injuries occasionally require extended tourniquet and surgical times and are vulnerable to sustaining concomitant vascular and neurologic injuries, which creates a potential for patients acquiring a venous thromboembolism (VTE). This complication has been reported to occur between 2% and 3.53% of multiligament cases, , which is comparable with the incidence seen in arthroscopic ACL cases. It is still unclear what risk factors place patients at greater risk of developing VTE/DVT), but obesity and substance abuse have been suggested in prior studies. Other general risk factors include personal and/or family history of previous VTE/DVT, smoking, oral contraceptive use or hormone replacement therapy, chronic venous insufficiency, and history of inherited hypercoagulopathy (i.e., factor V Leiden mutation). Patients with these risk factors should be considered for more definite anticoagulation therapies to minimize their risks for a DVT.
Intraoperative complications during surgical treatment of multiligament injuries have a higher risk of technical issues owing to local trauma, nondisplaced fractures, and poorer tissue quality. Limb- or life-threatening damage to vascular or neurologic structures within the knee requires a thorough examination because damage to structures like the CPN and popliteal artery can be easily overlooked in the face of high-velocity knee dislocations. In additional, although physicians may be up to date on the most optimal surgical protocol for isolated reconstruction procedures, failing to account for additional structure injuries in multiligament procedures could result in issues such as tunnel convergence, which may ultimately result in graft failure. The routine use of prophylactic antibiotics should help to minimize the risk of infection, and a well-prepared and knowledgeable surgical team can help to decrease the operative time and lead to reduced pain and swelling postoperatively.
Surgical Management of Vascular and Neurological Injuries
Treatment of vascular injuries requires immediate action, because delayed treatment may result in the need for amputation of the limb. Earlier literature advocated for nonoperative treatment of patients with vascular injuries, but this has recently been overruled by the support of data suggesting surgical treatment provides patients with significantly better IKDC subjective outcome scores and higher rates of return to work/sport following surgery. , , , ,
Open-wound injuries should be managed immediately, whereas closed-wound injuries should be given a necessary period to heal; when surgical management is needed, transfer procedures to include nerve repair have yielded enhanced neural regeneration and positive outcomes in some studies, but much work still needs to be done to improve outcomes for these procedures. For injuries involving the CPN, nerve function should be thoroughly evaluated and documented preoperatively, intraoperatively, and immediately postoperatively.
Surgically, most CPN injuries, including those classified as neuropraxia or axonotmesis, can be treated with a neurolysis followed by observation postoperatively to evaluate the return of sensory-motor function. It is extremely important to release sufficient scarring and tissues around the nerve to account for postoperative swelling and avoid a foot drop complication postoperatively. In addition, the proximal aspect of the peroneus longus fascia may be incised to ensure ample space for the course of the CPN postoperatively. For CPN injuries classified as neurotmesis with an associated foot drop, a multiligament knee reconstruction surgery can be performed in the first stage followed by a posterior tibial tendon transfer surgery in the second stage. However, motor function and chronicity should be determined to evaluate the chance of success with and without tendon transfer surgery. In chronic cases with an associated foot drop, the posterior tibial tendon transfer surgery may be performed before the multiligament knee reconstruction.
The optimal tunnel positioning for isolated anatomic reconstructions have been well described in the literature, but in cases of multiligament knee injuries, deviations of the tunnel trajectories are required. Tunnel convergence is the occurrence of reconstruction tunnels being placed too close in proximity to each other, and ultimately results in an elevated risk of graft failure caused by the lack of sufficient bone between graft tunnels for fixation and incorporation, in addition to the possibility of damaging the fixation devices or the reconstruction graft itself.
Recent studies have significantly improved the optimal treatment protocol for PCL injuries through a greater understanding of the anatomic attachments of both the posteromedial and anterolateral bundles and the codominant relationship between these bundles during loading, , and have validated this treatment protocol through outcomes studies with findings demonstrating comparable results with ACL reconstructions. However, the additional tunnels created through this improved technique create the potential for tunnel convergence, which needs to be kept in mind during multiligament surgeries that involve femoral-based reconstruction tunnels for the posterior oblique ligament (POL) or superficial medial collateral ligament (sMCL). Moatshe et al. and Camarda et al. suggested that lateral femoral tunnels for the FCL and POL should be angled between 35 and 40 degrees in the axial plane and 0 degrees in the coronal plane, and medial femoral tunnels for the sMCL should be angled at 40 degrees axial and 20 degrees coronal ( Fig. 19.3 ).