Surgical treatment of acl-pcl-medial side-lateral-side injuries of the knee

Anatomy 

Stability of the knee is due to several anatomic structures. The articulation of the femorotibial joint is maintained in part by the bony anatomy of the femoral condyles and the tibial plateau. The menisci serve to increase the contact area between femur and tibia and thus increase stability of the joint. The 4 major ligaments (ACL, PCL, MCL, LCL) and the posterior medial and posterior lateral corners are the most significant ligamentous stabilizers of the knee. In addition to these static anatomic structures, dynamic anatomic structures, such as the musculature that crosses the knee joint, also play a role in stabilization. In any knee injury, examination must include evaluation of all these anatomic structures.

When evaluating a dislocated knee, it is imperative to evaluate the structural integrity of any remaining ligamentous structure; consequently, the functions of these structures must be well understood. The ACL primarily prevents anterior translation of the tibia relative to the femur, and accounts for about 86% of the total resistance to anterior tibial translation.1 It is also involved in limiting internal and external rotation of the tibia relative to the femur when the knee is in extension.2 The ACL will also limit varus and valgus stress in the face of either LCL or MCL injury.

The PCL may be considered the primary static stabilizer of the knee, given its location near the center of rotation of the knee and its relative strength.3 The PCL has been shown to provide 95% of the total restraint to posterior tibial displacement forces acting on the tibia.1 The PCL works in concert with structures of the posterior lateral corner, and injury to both structures is required to significantly increase posterior translation.4

The MCL and LCL act alone to resist valgus and varus stresses, respectively, at 30° of knee flexion. Together, they act in a secondary fashion to limit anterior and posterior translation, and rotation of the tibia on the femur. The anatomy of the posterior lateral corner of the knee is complex; its major structures consist of the following: 1) the LCL; 2) the arcurate complex; 3) the popliteal tendon; and 4) the popliteal-fibular ligament.5 The posterolateral corner primarily resists posterior lateral rotation of the tibia relative to the femur, but also contributes to resisting posterior tibial transation. The posteromedial corner of the knee consists primarily of the posterior oblique portion of the MCL and associated joint capsule. These structures provide resistance to valgus stress and posterior medial tibial translation. Evaluation of traumatic knee dislocation must include these anatomical structures; typically, 3 areas or more are injured in knee dislocation. Failure to recognize and treat capsular and ligamentous injury, besides the obvious ACL/PCL injury, will result in less than optimal results.6, 7, 8

Neurovascular structures are also at risk of injury. The popliteal fossa is defined by the tendons of the pes anserinus and semimembranosus medially and the biceps tendon laterally. The space is closed distally by the medial and lateral heads of the gastrocnemius and proximally by the hamstrings. Within this space, the popliteal artery and vein and the tibial and peroneal branches of the sciatic nerve are located. The popliteal artery may be most at risk to injury in knee dislocations. The popliteal artery is tethered proximally at the adductor hiatus as it exits from Hunter’s canal, and distally as it passes under the soleus arch, making it vulnerable to injury in these areas. This artery is considered to be an “end artery” of the lower limb; if it is injured, the surrounding geniculate arteries are not sufficient to maintain collateral blood flow to the lower extremity. The popliteal vein is in close association with the artery, but seems less at risk during injury than the popliteal artery. From a surgical standpoint, the popliteal vessels are located directly posterior to the posterior horns of the medial and lateral meniscus, and dissection in this area may put these structures at risk if not adequately protected. The sciatic nerve divides into its peroneal and tibial divisions within the popliteal space. These nerves are less likely to be injured with knee dislocation, probably because they are not tethered as is the popliteal artery. The peroneal nerve does seem to be at higher risk, because its course around the fibular head functionally decreases its potential excursion, and violent varus injuries may result in traction injury to this nerve. Its location must be identified during dissections to reconstruct the posterolateral corner.

Classification 

Classification of knee dislocation is primarily based on the direction the tibia dislocates relative to the femur.9, 10 This results in 5 different catagories: anterior, posterior, lateral, medial, and rotatory. The anterior—medial and lateral posterior-medial and lateral dislocations are classified as “rotatory” dislocation. Other factors to be considered include the following: 1) whether the injury is open or closed; 2) whether the injury is due to “high-energy” or “low-energy” trauma; 3) whether the knee is completely dislocated or subluxed; and 4) whether there is neurovascular involvement. Furthermore, one should be acutely conscious of the fact that a complete dislocation may spontaneously reduce, and any triple-ligament knee injury constitutes a frank dislocation.7, 11, 12

Reports vary, but anterior and/or posterior dislocation appear to be the most common direction of dislocation. Frassica et al13 found a 70% incidence of posterior, 25% incidence of anterior, and 5% incidence of rotatory dislocations in their series. Green14 reported a 31% anterior, 25% posterior, and 3% rotatory dislocation in his series. Rotatory dislocations occur less frequently; however, the posterolateral dislocation seems to be the most common combination. This particular pattern may be irreducible secondary to the medial femoral condyle becoming “button-holed” through the anteromedial joint capsule. In addition, the MCL invaginates into the joint space, blocking reduction. This “button-holing” results in a “skin furrow” along the medial joint line, as the subcutaneous tissue attachments to the joint capsule drag the skin into the joint.15 Attempts at reduction in this senerio make the skin furrow more pronounced.

The actual incidence of different directional dislocation is not as important as correctly diagnosing the direction of injury, and determining how it relates to potential neurovascular injury. Hyperextension injuries (or posterior dislocations), because of the tethered popliteal artery and vein, may have the highest incidence of associated vascular injury; however, any dislocation, if initial displacement is severe enough, will result in injury to the popliteal artery. The common peroneal nerve is less at risk because it has a greater excursion than the popliteal vessels, but it is still susceptible when a varus force is applied to the knee. Posterolateral dislocation is associated with a high incidence of injury to the common peroneal nerve.16, 17

Open knee dislocations are not uncommon. Reported incidence is between 19% and 35% of all dislocations.17, 18 An open knee dislocation, in general, caries a worse prognosis secondary to severe injury to the soft-tissue envelop. Furthermore, an open injury may require an open ligament reconstruction, or staged reconstruction, because arthroscopically assisted techniques cannot be performed in the acute setting with these open injuries.

Distinguishing between low- and high-energy injuries is important. Low-energy or low-velocity injuries, usually associated with sports injuries, have a decreased incidence of associated vascular injury. High-energy or high-velocity injuries, secondary to motor vehicle accidents or falls from height, tend to have an increased incidence of vascular compromise. With decreased pulses in an injured limb and the history of a high-energy injury, one should obtain vascular studies urgently.

Mechanism of injury 

The mechanism of injury for the 2 most common knee-dislocation patterns, anterior and posterior, are reasonably well described. Kennedy16 was able to reproduce anterior dislocation by a hyperextension force acting on the knee. At 30° of hyperextension, Kennedy found that the posterior capsule failed. When extended further, to about 50°, the ACL, PCL, and popliteal artery fail. There is some question as to whether the ACL or the PCL fails first with hyperextension;16, 19 however, in our clinical experience,7 both the ACL and PCL fail with dislocation. Others’ series have demonstrated both ACL and PCL tears with complete knee dislocation.13, 20, 21

A posterior directed force applied to the proximal tibia when the knee is flexed to 90° is thought to produce a posterior dislocation, the so-called “dashboard” injury.20 Medial and lateral dislocations result from varus/valgus stresses applied to the knee. A combination of varus/valgus stress with hyperextension/blow to proximal tibia will likely produce one of the rotatory dislocations.

Associated injuries 

Several anatomic structures are at risk in the dislocated knee. The 4 major ligaments of the knee and the posterior medial and lateral corners can be compromised. Vascular and nerve injuries are common. There may be also associated bony lesions, avulsion fractures of the ACL or PCL, frank tibial plateau or distal femur condylar fractures, or ipsilateral tibial or femoral shaft fractures.

There is evidence in the literature that a frank dislocation may not result in complete rupture of 3 of the 4 major ligaments;16, 17, 22 however, this seems to be the exception rather than the rule. Several authors in their series have found that a frank dislocation of the knee invariably results in the rupture of at least 3 of the 4 major ligaments. Sisto and Warren21 found that all knees in their series had 3 or more ligaments compromised. In the Frassica et al13 series, all 13 patients treated operatively were found to have ACL, PCL, and MCL disruptions. In the Fanelli et al7 series, 19 of 20 were found to have a third component (posterior lateral corner or MCL) in addition to complete ACL and PCL disruption. With a frank dislocation of the knee, careful ligament examination is necessary to fully diagnose the extent of the injury.

The incidence of vascular compromise in knee dislocations has been estimated to be about 32%.14 When limited to anterior or posterior dislocation, the incidence may be as high as 50%.23 Recent studies confirm the significant incidence of arterial injury,13, 21, 24, 25 reaffirming the need for careful vascular evaluation. The popliteal artery is an “end-artery” to the leg, with minimal collateral circulation through the genicular arteries. Furthermore, the popliteal vein is responsible to the majority of venous outflow from the knee. If either structure is compromised to the point of prolonged obstruction, then ischemia and eventual amputation is often the result.26, 27

Two mechanisms have been described for injury to the popliteal artery. One is a “stretching” mechanism, seen with hyperextension, until the vessel ruptures. This may occur secondary to the “tethered” nature of the artery at the adductor hiatus and the entrance through the gastroc—soleus complex. This type of injury should be suspected with an anterior dislocation. Posterior dislocations may cause direct contusion of the vessel by the posterior plateau, resulting in intimal damage. Under no circumstance should compromised vascular status be attributed to arterial spasm; in this circumstance, there is often intimal damage and impending thrombosis formation. Cone28 points out that initial examination may be normal; however, thrombus formation can occur hours to days later,28, 29, 30, 31 and recent series have demonstrated delayed thrombus formation.13, 21 Furthermore, bicruciate ligament ruptures presenting as a “reduced” dislocated knee may have as high an incidence of arterial injury as a frank dislocation.12

Popliteal vein injury occurs much less frequently, or at least has not been reported historically. Despite this, venous occlusion must also be recognized and appropriately treated. Historically, whether to repair venous injury seemed controversial. Ligating the popliteal vein, which was a common practice during the Vietnam conflict, led to severe edema, phlebitis, and chronic venous stasis changes. Venous repair was thought to lead to thrombophlebitis and pulmonary embolism. Currently, if obstruction to outflow is recognized, then surgical repair of the popliteal vein is warranted.32

Injury to either the peroneal nerve or the tibial nerve has been documented 16, 17, 21, 22, 23, 24, 25, 33 with an incidence of about 20% to 30%. The nervous structures about the knee are not as tightly anchored as the popliteal vessels; this probably accounts for the lower incidence of injury compared with neighboring vascular structures. The mechanism of injury is usually one of stretch. The peroneal nerve seems to be more frequently involved than the tibial nerve, probably due to its anatomical location. With any varus loading of the knee, the peroneal nerve is placed under tension. In Shields’17 series, posterior dislocation caused the majority of the nerve injuries.

Given the fact that knee dislocation is usually secondary to violent trauma, associated fractures are common; the incidence may be as high as 60%.22 Tibial plateau fractures and avulsion fractures from the proximal tibia or distal femur are common.13, 18, 21, 22, 33, 34 Recognition of these injuries is also important because additional bony involvement has implications on definitive treatment. Associated distal femur fractures and proximal tibial fractures treated with intramedullary nailing make bone-tunnel placement for ACL and PCL reconstruction difficult. With violent trauma, any fracture or avulsion conceivable may occur with a dislocated knee; however, there is suggestion that medial and lateral dislocations are associated with some increased frequency of minor bony lesions.35

Fracture—dislocations represent a separate entity in the spectrum of pure knee dislocation to tibial plateau fractures. Pure knee dislocation requires only soft-tissue reconstruction to gain stability; tibial plateau fractures require purely bony stabilization. Fracture—dislocations of the knee often involve both bony and ligamentous repair or reconstruction, adding an element of complexity to their treatment.10, 36 Long-term outcome of fracture—dislocation injuries to the knee joint falls somewhere between tibial plateau fractures and pure dislocations, with tibial plateau fractures doing the best and dislocations the worst.36

Initial evaluation and management 

General considerations and physical examination 

Obvious deformity may be present on initial examination. However, in a polytrauma patient who is intubated and sedated, the injury may escape initial evaluation (Fig 1). Abrasions or contusions about the knee, gross crepitus, or laxity may allude to injury in an otherwise normal-appearing knee. This importance of immediate recognition of knee dislocation or fracture dislocation lay not with the treatment of instability, but the recognition of potential vascular injury and possible vascular compromise.12 Neurovascular status must be assessed on both lower extremities. Neurologic examination may be difficult in the polytrauma patient, and is not as important initially as serial neurologic examination. Vascular examination is more pressing because ischemia greater than 8 hours usually results in amputation.14 In the reduced knee, a white, cool limb that is obvious on physical examination and denotes arterial damage requires immediate arteriogram. However, normal pulses, Doppler signals, and capillary refill do not rule out an arterial injury.28 Thrombosis may occur hours to days later, necessitating serial examination. If there is any question of perfusion of the limb, then arteriogram is warranted.

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Fig 1. Multiple-trauma patient with left knee ACL/PCL/MCL tears, and right knee ACL/posterolateral corner tears.

The presence of a “dimple sign”37 on the antero-medial surface should be recognized. This indicates a postero-lateral dislocation and is associated with a high incidence of irreduceability and potential skin necrosis.37 In this circumstance, open reduction is warranted.

Imaging studies 

Before any manipulation, anteroposterior and lateral radiographs of the affected extremity should be completed. This is important to confirm the direction of dislocation and any associated fractures and aids in planning the reduction maneuver. In the presence of cyanosis, pallor, weak capillary refill, and decreased peripheral temperature after reduction, arteriography must be considered (Fig 2, A and B). Venography may be required if the clinical picture indicates adequate limb perfusion but obstruction of outflow.

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Fig 2. (A) Lateral radiograph of anterior tibiofemoral knee dislocation. (B) Arteriogram after closed reduction of dislocated knee documenting vascular status of the extremity.

After acute management of the dislocated knee, a magnetic resonance image may be obtained subacutely to confirm, and aid in planning the reconstruction of, compromised ligamentous structures.

Definitive surgical management 

Graft selection 

The ideal graft material should be strong, provide secure fixation, be easy to pass, be readily available, and have low donor-site morbidity. The available options in the United States are autograft and allograft sources. Our preferred graft for the PCL is the Achilles tendon allograft because of its large cross-sectional area and strength, the absence of donor-site morbidity, and easy passage with secure fixation (Fig 3). We prefer Achilles tendon allograft or bone—patellar tendon—bone allograft for ACL reconstruction. The preferred graft material for the posterolateral corner is a split biceps tendon transfer, or free autograft (semitentinosus) or allograft (Achilles tendon) tissue when the biceps tendon is not available.46, 47 Cases requiring MCL and posteromedial corner surgery may have primary repair, reconstruction, or a combination of both. Our preferred method for MCL and posteromedial reconstructions is a posteromedial capsular advancement with autograft or allograft supplementation as needed.

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Fig 3. Prepared Achilles tendon allograft. The graft is tubed for easy passage and to fill the bone tunnels. No. 5 braided permanent sutures are woven through the ends of the graft for traction and/or fixation.

Surgical approach 

Our preferred surgical approach is a single-stage arthroscopic combined ACL/PCL reconstruction by using the transtibial technique with collateral/capsular ligament surgery as indicated. The posterolateral corner is repaired, and than augmented with a split biceps tendon transfer, biceps tendon transfer, semitendinous free graft, or allograft tissue. Acute medial injuries not amenable to brace treatment undergo primary repair and posteromedial capsular shift or allograft reconstruction as indicated. The operating surgeon must be prepared to convert to a dry arthroscopic procedure, or to an open procedure if fluid extravasation becomes a problem (Fig 4).

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Fig 4. Open ACL/PCL/MCL reconstruction in a dislocated knee. Severe capsular destruction prevented an arthroscopic procedure from being performed.

Surgical technique 

The principals of reconstruction in the multiple-injured knee are to identify and treat all pathology, accurate tunnel placement, anatomic graft insertion sites, utilize strong graft material, secure graft fixation, and a deliberate postoperative rehabilitation program.

The patient is positioned supine on the operating-room table. The surgical leg hangs over the side of the operating table, and the well leg is supported by the fully extended operating table. A lateral post is used for control of the surgical leg. We do not use a leg holder. The surgery is performed under tourniquet control, unless prior arterial or venous repair contraindicates the use of a tourniquet. Fluid inflow is by gravity. We do not use an atthroscopic fluid pump.

Allograft tissue is prepared before bringing the patient into the operating room. Arthroscopic instruments are placed with the inflow in the superior lateral portal, arthroscope in the inferior lateral patellar portal, and instruments in the inferior medial patellar portal. An accessory extracapsular extra-articular posteromedial safety incision is used to protect the neurovascular structures, and to confirm the accuracy of tibial tunnel placement (Fig 5).

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Fig 5. A 1- to 2-cm extracapsular extra-articular posteromedial safety incision allows the surgeon’s finger to protect the neurovascular structures, confirm the position of the PCL instruments and drill guide on the posterior aspect of the proximal tibia, and assure the accuracy of PCL tibial tunnel placement both in the medial-lateral and proximal-distal planes.

The notchplasty is performed first and consists of ACL and PCL stump debridement, bone removal, and contouring of the medial wall of the lateral femoral condyle and the intercondylar roof. This allows visualization of the over-the-top position, and prevents ACL graft impingement throughout the full range of motion. Specially curved PCL instruments are used to elevate the capsule from the posterior aspect of the tibia (Arthrotek, Warsaw, IN; Fig 6).

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Fig 6. Curved PCL instruments enable the surgeon to elevate the capsule from the posterior proximal tibia (Arthrotek).

The PCL tibial and femoral tunnels are created with the help of a PCL/ACL drill guide (Arthrotek; Fig 7). The transtibial PCL tunnel goes from the anteromedial aspect of the proximal tibial 1 cm below the tibial tubercle to exit in the inferior lateral aspect of the PCL anatomic insertion site (Fig 8). The PCL femoral tunnel originates externally between the medial femoral epicondyle and the medial femoral condylar articular surface to emerge through the center of the stump of the anterolateral bundle of the PCL (Fig 9). The PCL graft is positioned and anchored on the femoral or tibial side, and left free on the opposite side.

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Fig 7. The PCL/ACL drill guide enables the surgeon to drill the PCL and ACL tibial and femoral tunnels.

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Fig 8. The PCL tibial tunnel should exit at the inferior and lateral aspect of the anatomic insertion site of the PCL.

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Fig 9. The PCL femoral tunnel enters the joint through the center of the anterolateral fiber region or bundle of the PCL anatomic insertion site. The single-bundle PCL reconstruction technique reproduces the anterolateral bundle of the PCL. The femoral drill hole is in the center of the anterolateral bundle of the PCL.

The ACL tunnels are created using the single-incision technique. The tibial tunnel begins externally at a point 1 cm proximal to the tibial tubercle on the anteromedial surface of the proximal tibia to emerge through the center of the stump in the ACL tibial footprint. The femoral tunnel is positioned next to the over-the-top position on the medial wall of the lateral femoral condyle near the ACL anatomic insertion site. The tunnel is created to leave a 1- to 2-mm posterior cortical wall so that interference fixation can be used. The ACL graft is positioned, and anchored on the femoral side, with the tibial side left free. Attention is then turned to the posterior lateral corner.

Our preferred technique for posterolateral reconstruction is the split biceps tendon transfer to the lateral femoral epicondyle (Fig 10). The requirements for this procedure include an intact proximal tibiofibular joint, the posterolateral capsular attachments to the common biceps tendon should be intact, and the biceps femoris tendon insertion into the fibular head must be intact. This technique creates a new popliteofibular ligament and lateral collateral ligament, tightens the posterolateral capsule, and provides a post of strong autogenous tissue to reinforce the posterolateral corner.

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Fig 10. The posterolateral reconstruction is performed by using a split biceps tendon transfer combined with a posterolateral capsular shift. This technique recreates the function of the popliteofibular ligament, and lateral collateral ligament, and eliminates the posterolateral capsular redundancy. The anterior two thirds of the long head and common biceps femoris tendon are isolated from the short head muscle. The tendon is detatched proximally and left attached distally to its anatomic insertion site. The peroneal nerve is protected. The split biceps tendon is passed medial to the iliotibial band, and secured to the lateral femoral epicondyle approximately 1 cm anterior to the fibular collateral ligament femoral insertion by using a cancellous screw and spiked ligament washer.

A lateral hockey-stick incision is made. The peroneal nerve is dissected free and protected throughout the procedure. The long head and common biceps femoris tendon is isolated, and the anterior two thirds is separated from the short head muscle. The tendon is detached proximal and left attached distally to its anatomic insertion site on the fibular head. The strip of biceps tendon should be 12 to 14 cm long. The iliotibial band is incised in line with its fibers, and the fibular collateral ligament and popliteus tendons are exposed. A drill hole is made 1 cm anterior to the fibular collateral ligament femoral insertion. A longitudinal incision is made in the lateral capsule just posterior to the fibular collateral ligament. The split biceps tendon is passed medial to the iliotibial band, and secured to the lateral femoral epicondylar region with a screw and spiked ligament washer at the abovementioned point. The residual tail of the transferred split biceps tendon is passed medial to the iliotibial band, and secured to the fibular head. The posterolateral capsule that had been previously incised is then shifted and sewn into the strut of transferred biceps tendon to eliminate posterolateral capsular redundancy.

Posteromedial and medial reconstructions are performed through a medial hockey stick incision (Fig 11). Care is taken to maintain adequate skin bridges between incisions. The superficial MCL is exposed, and a longitudinal incision is made just posterior to the posterior border of the MCL. Care is taken not to damage the medial meniscus during the capsular incision. The interval between the posteromedial capsule and medial meniscus is developed. The posteromedial capsule is shifted anterosuperiorly. The medial meniscus is repaired to the new capsular position, and the shifted capsule is sewn into the MCL. When superficial MCL reconstruction is indicated, this is performed with allograft tissue or semitendinosus autograft. This graft material is attached at the anatomic insertion sites of the superficial MCL on the femur and tibia. The posteromedial capsular advancement is performed, and sewn into the newly reconstructed MCL.

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Fig 11. Posteromedial reconstruction performed through a medial hockey-stick incision by using posteromedial capsular shift procedure.

Graft tensioning and fixation 

The PCL is reconstructed first, followed by the anterior cruciate, followed by the posterolateral complex and/or posterior medial corner. Tension is placed on the PCL graft distally, and the knee is cycled through a full range of motion 25 times to allow pretensioning and settling of the graft. The knee is placed in 70° to 90° of flexion, a firm anterior drawer force is applied to the proximal tibia to restore the normal tibial step-off, and fixation is achieved on the tibial or femoral side of the PCL graft with a screw and spiked ligament washer and a bioabsorable interference screw. The knee is then placed in 30° of flexion, the tibial internally rotated, slight valgus force applied to the knee, and final tensioning and fixation of the posterolateral corner is achieved. The knee is returned to 70° to 90° of flexion, a posterior drawer force is applied to the proximal tibia with tension on the ACL graft, and final fixation is achieved of the ACL graft with a bioabsorbable interference screw and spiked ligament washer back-up fixation. Reconstruction and tensioning of the MCL and posteromedial corner are performed after the ACP, PCL, and PLC reconstructions, and are performed in 30° of knee flexion.

Technical hints 

The posteromedial safety incision protects the neurovascular structures, confirms accurate tibial tunnel placement, and allows the surgical procedure to be performed at an accelerated pace. The single-incision ACL reconstruction technique prevents lateral cortex crowding and eliminates multiple through-and-through drill holes in the distal femur, reducing the stress riser effect. It is important to be aware of the 2 tibial tunnel directions, and to have a 1-cm bone bridge between the PCL and ACL tibial tunnels (Fig 12). This will reduce the possibility of fracture. We have found it useful to use primary and back-up fixation. Primary fixation is with resorbable interference screws, and back-up fixation is performed with a screw and spiked ligament washer. Secure fixation is critical to the success of this surgical procedure.

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Fig 12. A model showing the tibial tunnel positions for combined ACL/PCL reconstructions. It is essential to have an adequate bone bridge between the 2 tunnels.

Results 

We have previously published the results of our arthroscopically assisted combined ACL/PCL and PCL/posterolateral complex reconstructions by using the reconstructive technique described in this chapter.6, 7, 8 Our most recently published 2 to 10 year results of combined ACL/PCL reconstructions are presented here.48

This study presented the 2- to 10-year (24–120 month) results of 35 arthroscopically assisted combined ACL/PCL reconstructions evaluated pre- and postoperatively by using Lysholm, Tegner, and Hospital for Special Surgery knee-ligament rating scales, KT 1000 arthrometer testing, stress radiography, and physical examination.

This study population included 26 males, 9 females, 19 acute, and 16 chronic knee injuries. Ligament injuries included 19 ACL/PCL/posterolateral instabilities, 9 ACL/PCL/MCL instabilities, 6 ACL/PCL/posterolateral/MCL instabilities, and 1 ACL/PCL instability. All knees had grade III preoperative ACL/PCL laxity, and were assessed pre- and postoperatively with arthrometer testing, 3 different knee-ligament rating scales, stress radiography, and physical examination. Arthroscopically assisted combined ACL/PCL reconstructions were performed by using the single-incision endoscopic ACL technique and the single femoral tunnel single-bundle transtibial tunnel PCL technique. PCLs were reconstructed with allograft Achilles tendon,26 autograft bone-tendon-bone,7 and autograft semitendinosus/gracilis.2 ACLs were reconstructed with autograft bone-tendon-bone,16 allograft bone-tendon-bone,12 Achilles tendon allograft,6 and autograft semitendinosus/gracilis.1 MCL injuries were treated with bracing or open reconstruction. Posterolateral instability was treated with biceps femoris tendon transfer, with or without primary repair, and posterolateral capsular shift procedures as indicated.

Postoperative physical examination results revealed normal posterior drawer/tibial step off in 16/35 (46%) of knees and normal Lackman and pivot shift tests in 33/35 (94%) of knees. Posterolateral stability was restored to normal in 6/25 (24%) of knees, and tighter than the normal knee in 19/25 (76%) of knees evaluated with the external rotation thigh foot angle test. Thirty-degree varus stress testing was normal in 22/25 (88%) of knees, and grade 1 laxity in 3/25 (12%) of knees. Thirty-degree valgus stress testing was normal in 7/7 (100%) of surgically treated MCL tears, and normal in 7/8 (87.5%) of brace-treated knees. Postoperative KT 1000 arthrometer testing mean side-to-side difference measurements were 2.7 mm (PCL screen), 2.6 mm (corrected posterior), and 1.0 mm (corrected anterior) measurements, a statistically significant improvement from preoperative status (P = 0.001). Postoperative stress radiographic side-to-side difference measurements measured at 90° of knee flexion and 32 lb of posteriorly directed proximal force were 0 to 3 mm in 11/21 (52.3%), 4 to 5 mm in 5/21 (23.8%), and 6 to 10 mm in 4/21 (19%) of knees. Postoperative Lysholm, Tegner, and HSS knee-ligament rating-scale mean values were 91.2, 5.3, and 86.8, respectively, demonstrating a statistically significant improvement from preoperative status (P = 0.001).

The conclusions drawn from the study were that combined ACL/PCL instabilities could be successfully treated with arthroscopic reconstruction and the appropriate collateral ligament surgery. Statistically significant improvement was noted from the preoperative condition at 2-to-10-year follow-up by using objective parameters of knee-ligament rating scales, arthrometer testing, stress radiography, and physical examination. Postoperatively, these knees are not normal, but they are functionally stable. Continuing technical improvements will most likely improve future results.

Another group of multiple-ligament reconstructions that warrant attention are our 2-to-10-year results of combined PCL-posterolateral reconstruction.49 This study presented the 2-to-10-year (24–120 month) results of 41 chronic arthroscopically assisted combined PCL/posterolateral reconstructions evaluated pre- and postoperatively by using Lysholm, Tegner, and Hospital for Special Surgery knee-ligament rating scales, KT 1000 arthrometer testing, stress radiography, and physical examination.

This study population included 31 males, 10 females, 24 left, and 17 right chronic PCL/posterolateral knee injuries with functional instability. The knees were assessed pre-and postoperatively with arthrometer testing, 3 different knee-ligament rating scales, stress radiography, and physical examination. PCL reconstructions were performed by using the arthroscopically assisted single femoral tunnel single-bundle transtibial tunnel PCL reconstruction technique with fresh frozen Achilles tendon allografts in all 41 cases. In all 41 cases, posterolateral instability reconstruction was performed with combined biceps femoris tendon tenodesis and posterolateral capsular shift procedures. The paired t-test and power analysis were the statistical tests used. Ninety-five percent confidence intervals were used throughout the analysis.

Postoperative physical examination revealed normal posterior drawer/tibial step off in 29/41 (70%) of knees. Posterolateral stability was restored to normal in 11/41 (27%) of knees, and tighter than the normal knee in 29/41 (71%) of knees evaluated with the external rotation thigh foot angle test. Thirty-degree varus stress testing was normal in 40/41 (97%) of knees, and grade 1 laxity in 1/41 (3%) of knees. Postoperative KT 1000 arthrometer testing mean side-to-side difference measurements were 1.80 mm (PCL screen), 2.11 mm (corrected posterior), and 0.63 mm (corrected anterior) measurements. This is a statistically significant improvement from preoperative status for the PCL screen and the corrected posterior measurements (P = 0.001). The postoperative stress radiographic mean side-to-side difference measurement measured at 90° of knee flexion, and 32 lb of posterior directed force applied to the proximal tibia by using the Telos device was 2.26 mm. This is a statistically significant improvement from preoperative measurements (P = 0.001). Postoperative Lysholm, Tegner, and Hospital for Special Surgery knee-ligament rating-scale mean values were 91.7, 4.92, and 88.7, respectively, demonstrating a statistically significant improvement from preoperative status (P = 0.001).

Conclusions drawn from this study were that chronic combined PCL/posterolateral instabilities could be successfully treated with arthroscopic PCL reconstruction by using fresh frozen Achilles tendon allograft combined with posterolateral corner reconstruction with biceps tendon transfer combined with posterolateral capsular shift procedure. Statistically significant improvement is noted (P = 0.001) from the preoperative condition at 2-to-10-year follow-up by using objective parameters of knee-ligament rating scales, arthrometer testing, stress radiography, and physical examination.

Conclusions 

Multiple-ligament injuries of the knee are complex injuries that require a systematic approach to evaluation and treatment. Gentle reduction and documentation and treatment of vascular injuries are primary concerns in the acute dislocated/multiple-ligament-injured knee. Arthroscopically assisted combined ACL/PCL reconstruction with appropriate collateral ligament surgery is a reproducible procedure. Knee stability is improved postoperatively when evaluated with knee-ligament rating scales, arthrometer testing, and stress radiographic analysis. Acute MCL tears when combined with ACL/PCL tears in certain cases may be treated with bracing. Posterolateral corner injuries combined with ACL/PCL tears are best treated with primary repair as indicated, combined with reconstruction by using a post of strong autograft (split biceps tendon, biceps tendon, semitendinosus) or allograft tissue. Surgical timing depends on the ligaments injured, the vascular status of the extremity, reduction stability, and the overall health of the patient. We prefer the use of allograft tissue for reconstruction in these cases because of the strength of these large grafts and the absence of donor-site morbidity.