Management of the Multiple Ligament-Injured Knee
Lindsey N. Dietrich
Dustin L. Richter
Daniel C. Wascher
Andrew J. Veitch
Robert C. Schenck
DEFINITION
Multiligament knee injuries result from both high-energy (eg, motor vehicle collisions) and low-energy (eg, athletic injuries, falls) events. Ultra-low velocity dislocations are those described in obese patients with minimal trauma. Dislocation of the tibiofemoral joint is common, with or without spontaneous reduction.
ANATOMY
Put very simply, knee dislocations can be viewed as injuries to one or both cruciate ligaments (ie, anterior cruciate ligament [ACL] or posterior cruciate ligament [PCL]), with variable involvement of the collateral ligaments (ie, the medial collateral ligament [MCL] and the fibular collateral ligament [FCL]) along with the popliteofibular ligament (PFL)/arcuate complex posterolaterally and the posterior oblique ligament (POL) medially. There are also important musculotendinous stabilizers—the biceps femoris and popliteus posterolaterally and the pes anserine complex medially, all of which must be considered in restoring knee function. Palpable bony landmarks about the knee are crucial to aid in orientation for examination and when planning subsequent surgical approaches.
The lateral femoral epicondyle, Gerdy tubercle, and the fibular head are critical to identify the placement of lateral incisions, as are anatomic structures such as the FCL and peroneal nerve. Medially, the femoral epicondyle, tibial tubercle, pes insertion site, and posteromedial tibial edge are crucial landmarks for medial surgical exposures for inlay and MCL reconstruction.
The intrinsic structure of the vascular system of the knee consists of an anastomotic ring of five geniculates: the superomedial, superolateral, inferomedial, inferolateral, and middle geniculates as well as muscular and articular branches.
The extrinsic system plays a crucial role when parallel medial or lateral incisions are made about the knee in the sagittal plane.
Proper planning should allow 7 to 10 cm between superficial parallel incisions to greatly lessen the risk of skin bridge loss, but it has been our experience that such incisions should be avoided if possible. This anastomotic network alone cannot support vascularity distal to the knee with popliteal vessel occlusion.
The surgical anatomy of the knee usually is described in layers, going from the superficial structures to the deep structures.42
Layer I is commonly described as consisting of the Marshall layer (arciform) anteriorly, the sartorius medially, and the iliotibial (IT) band and biceps femoris fascia laterally.
Layer II includes the FCL, patellar tendon, and superficial MCL.
Layer III includes the posterior oblique, arcuate ligament, and deep portion of the MCL. Layer III is thin anteriorly and has distinct, structurally important thickenings posteromedially (POL) and posterolaterally (arcuate ligament). A Segond fracture is caused by avulsion of the thickened middle third of the lateral knee capsule in this layer. Layer III is simplistically described as variations in the joint capsule.
Posterolateral reconstructions are complex because of this anatomy and variability and require restoration of both the FCL and PFL as well as the proximity of the peroneal nerve. Because the lateral aspect of the knee is less commonly explored, some authors have described it as “the dark side of the knee.”
The surgeon should understand the important anatomic relationships of the posterior structures of the knee, especially in regard to the popliteal neurovascular bundle.
The medial and lateral heads of the gastrocnemius are the borders of the popliteal fossa distally, the pes anserinus tendons medially, and the biceps femoris tendon laterally. The popliteus, posterior joint capsule, oblique popliteal ligament, and posterior femoral cortex form the floor of the fossa. Through this fossa run the plantaris muscle and the neurovascular structures. The popliteal artery enters through the adductor magnus superiorly as it leaves Hunter canal, courses through the fossa, and exits through the soleal arch. The popliteal vein enters superolateral to the artery and continues superficial to the artery but is located deep to the tibial and common peroneal nerves, leaving the fossa medial to the popliteal artery.
The vascular structures are located directly behind the posterior horns of the medial and lateral menisci. The vascular structures are protected during posteromedial and posterolateral approaches if the surgeon remains anterior to the medial and lateral heads of the gastrocnemius during dissection and careful retraction; the surgeon should be cautioned that further dissection toward the midline can injure the neurovascular bundle with either approach.
With the advent of posterior procedures to the tibial side of the PCL, it is critical to understand the posterior neurovascular anatomy. The posteromedial approach also is useful to gain access to the tibial insertion of the PCL.
Deep dissection along the posterior tibial surface and femoral condyles provides additional safety for this approach. Use of a tourniquet during dissection provides improved visualization of the surgical planes.
Unlike the vascular surgeon, who uses a posteromedial approach for the neurovascular (popliteal) bundle, the
orthopaedic surgeon dissecting posteromedially should avoid the neurovascular bundle. Staying anterior to the medial gastrocnemius and hugging the posterior aspect of the knee joint protects the bundle in the orthopaedic approach.
It is important to stop the dissection at the PCL because further dissection laterally with this approach eventually will reach and potentially injure the bundle.
NATURAL HISTORY
Before the development of modern surgical techniques for management of multiligament injuries, scores of patients were left with stiff, unstable, or even amputated limbs. Today, even with aggressive evaluation and treatment, patients ultimately may have residual instability with a lower level of activity, decreased range of motion (ROM), osteoarthritis, and even amputation. The use of allografts in multiligamentinjured knees is a recent advance, although occasionally, it is complicated by deep infection or rejection.
PATIENT HISTORY AND PHYSICAL FINDINGS
During the initial evaluation of a patient with a suspected multiligament knee injury, the clinician should be cognizant of the potential for concomitant injuries. High- or lowenergy knee trauma can have potentially life- or limbthreatening injuries, which must be identified acutely.
Once any life-threatening injuries have been treated, a careful injury history should be obtained if possible, including prehospital neurovascular status of the limb, time of injury, and mechanism. Patients often relate a history of hyperextension of the knee in sporting events or a flexed knee that struck the dashboard during a motor vehicle accident.
Complete examination of the injured limb focuses both above and below the knee to evaluate for fracture as well as continuity of the extensor mechanism. In suspected knee dislocations, a complete ligamentous examination is crucial. Increased varus or valgus laxity in full extension as compared to 30 degrees of flexion may indicate collateral and concomitant cruciate disruption. The dial test in the prone position is useful for evaluating posterolateral corner (PLC) and PCL injuries. A posterior Lachman maneuver can also be used to evaluate PCL continuity. For the obese, swollen, or painful patient, a stabilized Lachman maneuver can be performed in which the examiner places his/her thigh behind the patient’s thigh to bolster and stabilize the femur.
Any evidence of current dislocation of the tibiofemoral joint should be addressed emergently, with attempted reduction under sedation, splinting, careful neurovascular examination pre- and postreduction, and high-quality radiographic evaluation following reduction.
The radiographic evaluation should include an anteroposterior and a lateral radiograph of the knee with the limb in a long-leg splint to demonstrate that a successful reduction has been achieved.
Medial furrowing of the soft tissues of the knee along the joint line usually suggests a posterolateral dislocation with buttonholing of the medial femoral condyle through the joint capsule, MCL incarceration into the joint, and irreducibility with closed methods of reduction (an irreducible or complex dislocation).12,41
Any asymmetry in the vascular examination from the uninjured extremity, even prehospital, necessitates further evaluation, with the specifics often dictated by vascular surgery protocols and regional preference.37
Many clinicians routinely obtain angiograms regardless of the vascular examination findings with multiligament injured knees.4 Nonetheless, the current trend toward using sequential clinical examinations in reduced dislocation with normal pulses (including normal neurovascular examination) is becoming more popular and is considered safe. FIG 1 describes the Stannard protocol for selective arteriography.
Use of Doppler or other noninvasive vascular laboratory studies in conjunction with an ankle-brachial index is very useful because these studies can provide objective information (rather than the subjective findings of pulses) and also avoid the invasiveness of angiography.27
Multislice computed tomographic angiography (MCTA) is a noninvasive imaging modality that is an alternative to the traditional gold standard of catheter-based angiography. It has been shown to be both sensitive and specific for arterial evaluation in the injured lower extremity.17
The surgeon must be aggressive in the management of any abnormal vascular findings, with immediate vascular consultation and immediate surgical exploration of ischemia in the reduced knee dislocation. Ischemia in the dislocated knee requires reduction and pulse or vascularity reevaluation. Continued ischemia from a popliteal artery injury for more than 6 to 8 hours results in amputation rates of up to 80%.15
IMAGING AND OTHER DIAGNOSTIC STUDIES
An integral part of evaluation of the multiligamentously injured knee is plain radiographs before and after reduction to confirm congruity of the joint, evaluate for associated fractures, and detect ligament avulsion injuries that may aid in timing of the treatment plan. Note that 50% of patients with a dislocated knee will have a reduced tibiofemoral joint on plain radiographs at the time of initial evaluation.
Magnetic resonance imaging (MRI) is an excellent adjunct to delineation of the extent of injury and pattern of ligament injury and musculotendinous and osteoarticular injuries. These studies are combined with a careful examination of the ligamentous structures, with and without anesthesia, which are compared with those in the uninjured extremity.
MRI cannot replace a careful clinical examination under anesthesia (EUA), which can determine functional ligamentous injury and the need for ligament reconstruction. EUA is particularly useful in these patients given the severity of injury and associated pain.
Arthroscopic EUA can be helpful to further evaluate injury to the medial and lateral structures in addition to MRI and physical exam findings at the time of definitive ligamentous reconstruction.
CLASSIFICATION
Multiple classification systems have been used to describe dislocations of the knee.
Historically, the most commonly used system has been based on a positional description of the tibial position
with respect to the femur when the knee is dislocated.14 However, this system is not without limitations.
FIG 1 • Stannard protocol for selective arteriography.
First, up to 50% of knee dislocations present spontaneously reduced, making classification based on position at the time of injury difficult, if not impossible.43
Second, this system does not provide information regarding the energy of the injury, the ligaments injured, or associated neurovascular injuries, all of which play a part in the overall treatment plan.
Classifying dislocations based on the anatomic injury pattern (ie, ligaments torn and associated neurovascular injuries) allows for adequate physician communication (especially for future reconstructions) and preoperative planning.5 The anatomic classification is shown in Table 1.
Fracture-dislocation of the knee as described by Moore29 in 1981 involves a ligamentous injury in association with a fracture of the tibial or femoral condyles. This entity should be distinguished from the purely ligamentous definition of the dislocated knee as outlined in Table 1. Avulsion injuries such as the Segond fracture, fibular head avulsion fractures, patellar tendon or biceps femoris tendon avulsions, and cruciate avulsions may occur in knee dislocations, but they should be considered ligamentous or tendinous injuries and not condylar injuries that destabilize the bony architecture of the knee.
Table 1 Anatomic Classification of Knee Dislocations | ||||||||||||||
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DIFFERENTIAL DIAGNOSIS
Knee dislocations can be difficult to assess in the presence of gross knee swelling or with the presentation of multitrauma or associated fractures.
Accurate detection of associated neurovascular injuries is critical.
Identification of the ligaments injured is based on the initial examination, imaging studies, and EUA.
NONOPERATIVE MANAGEMENT
Many patients today are treated with surgical management of some type; however, depending on their injury pattern, there are still subsets who are treated nonoperatively. These include patients with severe comorbidities that increase the risks of surgery or those with open dislocations or greatly damaged soft tissue envelopes, where the focus is on restoring the envelope and treating infection.
Cast Immobilization
Although the cast immobilization technique was used for many years to treat multiligament injuries to the knee before modern reconstructive procedures were available, closed treatment as definitive management rarely is indicated.
Immobilization in extension/slight flexion for 6 weeks, as described by Taylor et al,39 can result in a stable knee but, in our experience, should be used only in circumstances where the preferred technique of ligamentous reconstruction is not applicable or feasible (arterial injury, open knee dislocation with severe soft tissue envelope injury).
External Fixation
External fixation may be used to span the knee joint with fixation in the tibia and femur and is useful in patients who have poor rehabilitation potential. It also may be used as a temporary stabilizing measure in open knee dislocations, severe soft tissue injuries, unstable reductions (especially KD IV injuries), and vascular reconstructions while awaiting optimal conditions for operative ligamentous reconstructions.
Advantages include adequate maintenance of reduction, access to soft tissue wounds, patient mobilization, and protection of maturing reverse saphenous vein grafts.
However, the potential for loss of knee motion, arthrofibrosis, and heterotopic ossification in greater than 40% of knees exists.21 These often require later manipulation under anesthesia and lysis of adhesions.
Hinged Knee Brace
The patient is placed in a hinged knee brace and reduction of the knee joint confirmed radiographically. Supervised ROM exercises are initiated in the first few weeks following the injury.
This treatment method is ineffective in creating a stable knee but is an extremely important step in the process to a successful multiligamentous reconstruction.
Gaining extension, a more normal gait pattern, full flexion, and decreased swelling (resolution of inflammation) add to an easier postoperative course, with avoidance of postoperative stiffness and heterotopic ossification with multiligamentous reconstruction. In our experience, multiligamentous reconstruction within 10 days of injury can have significant risks of stiffness and a clinically inferior outcome.
The work of Shelbourne34 and others with ACL/MCL injuries with preoperative rehabilitation is even more applicable to multiligament knee injuries. Obtaining preoperative ROM before PCL, ACL, and collateral ligament reconstruction is extremely useful in obtaining a stable, pain-free knee after dislocation.
SURGICAL MANAGEMENT
Indications
Surgical intervention produces better clinical outcomes than nonoperative management of the multiligament injured knee.21
Operative reconstruction is recommended to most patients with multiligament knee injuries. In some cases, an external fixator is used temporarily, followed by surgical reconstruction; in most cases, early braced knee motion is instituted with delay of reconstruction of ligament injuries undertaken only after motion is restored and inflammation is resolved.
Ligamentous repair (ie, suture repair) is now only occasionally used. Failure rates of up to 40% have been reported with primary repair of the FCL/PLC,20 whereas loss of flexion and inferior return to preinjury levels of activity have been documented with cruciate repairs.23 It is noteworthy, however, that revision reconstructions after failed repair of collateral structures may yield results similar to those of primary reconstructions.
Crucial to the immediate care of these injuries is a meticulous neurovascular examination. Any vascular deficit necessitates emergent vascular surgery consultation and consideration for an open popliteal artery exploration and reverse saphenous vein graft reconstruction.
The optimal timing for surgical intervention is not clearly defined. Multiple investigators have advocated acute (within 3 weeks) surgical management of knee dislocations.9,34 However, these findings are not universal and caution should be used in selecting early surgical candidates because higher energy injuries, concomitant vascular insult, and soft tissue integrity all play a role in optimizing the timing of surgery. Generally, the authors advocate waiting for several weeks after the injury before performing surgical reconstruction of these multiligamentous injuries in order to regain motion, decrease inflammation, and allow maturation of vascular grafts or repairs when performed.
Both single procedure and staged reconstructions are described for multiligamentous injuries. The decision is based on surgeon experience as well as the pattern and severity of the collateral injuries. If staged reconstruction is undertaken, collateral reconstruction precedes cruciate reconstruction.21
Authors’ Preference
In our experience, it is best to wait for preoperative motion, gait, and swelling to improve. Over 22 years of experience with knee dislocations has led to the following guidelines:
Delayed reconstruction is better than immediate surgery.
Preoperative rehabilitation is useful to regain motion, and resolution of swelling and inflammation is critical to surgical success.
Reconstruction is done with allo- and autografts, avoiding surgical repairs unless combined with reconstruction.
Both cruciates and involved collateral(s) are reconstructed simultaneously.
Approach
Graft Choice
Many graft choices are available for ACL reconstruction in the multiligament-injured knee. We prefer a bone-patellar tendon-bone (BTB) or soft tissue allograft.
Although a BTB autograft is the gold standard in an isolated ACL reconstruction, the comorbidities of ipsilateral graft harvest in combined ACL-PCL injuries can result in stiffness, especially in simultaneous cruciate reconstruction.
The ipsilateral hamstring autograft should not be considered for a cruciate graft in a type III knee dislocation (KD IIIM) because the hamstrings provide a secondary restraint to valgus load and are preferentially used for MCL reconstruction.
Allografts are ideal for the multiligamentous knee injury. Allograft Achilles tendon and quadriceps tendon with bone blocks work well for PCL and PLC reconstructions, respectively, whereas hamstring allografts can be useful for ACL and MCL reconstructions.
The following graft selections represent autograft options for patients who decline the use of allograft tissue:
PCL reconstruction: ipsilateral or contralateral quadriceps tendon autograft
ACL reconstruction: ipsilateral or contralateral patella BTB tendon autograft
KD IIIM: contralateral semitendinosus and gracilis (ACL), ipsilateral quadriceps (PCL), and ipsilateral semitendinosus (MCL)
KD IIIL or KD IV: Arciero-type lateral reconstruction using ipsilateral or contralateral semitendinosus or biceps femoris tenodesis procedure
Posterior Cruciate Ligament Reconstruction
A number of approaches to modern PCL reconstruction are available, including (1) transtibial and femoral tunnels (with or without dual femoral socket) and (2) tibial inlay using a single or dual femoral tunnel in which tibial fixation is achieved by securing a bone plug into a trough positioned at the anatomic insertion of the PCL.
Significant differences in graft thinning and elongation, as well as differences in failure rates (32% transtibial, 0% inlay), have been shown in a biomechanical model of the two techniques, favoring the inlay technique. However, significant clinical differences have not been demonstrated between tibial tunnel and inlay PCL reconstructions and indeed transtibial PCL reconstructions have excellent long-term clinical stability.26
There is no consensus on single versus double-bundle reconstruction of the PCL. Although many investigators have demonstrated decreased residual laxity with doublebundle reconstructions,46,48 clinical and functional superiority has not been definitively established.6Related posts:
Arthroscopic Treatment of Posterior Shoulder Instability
Glenoid Bone Graft for Instability with Bone Loss
Snapping Hip/Lateral Hip
Repair of Acute and Chronic Patella Tendon Tears
Anterior Cruciate Ligament Reconstruction in the Skeletally Immature Patient
Modified Brostrom and Brostrom-Evans Procedures
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