Combined anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) disruptions are uncommon orthopaedic injuries. They are usually caused by high- or low-velocity knee dislocations. Because knee dislocations might spontaneously reduce before initial evaluation, the true incidence is unknown. Dislocation involves injury to multiple ligaments of the knee. Both of the cruciate ligaments are usually disrupted, and they are often combined with a third ligamentous disruption (medial collateral ligament or lateral collateral ligament and/or posterior lateral complex). Associated neurovascular, meniscal, and osteochondral injuries are often present and complicate treatment.

Classification Knee dislocations are classified by relating the position of the displaced tibia on the femur; anterior, posterior, medial, lateral, or rotational. Both cruciate ligaments might be disrupted in all these injuries. A rotatory knee dislocation occurs around one of the collateral ligaments (LCL) leading to a combined ACL and PCL injury and a tear of the remaining collateral ligament. Knee dislocations that spontaneously reduce are classified according to the direction of instability. Knee dislocations are classified as acute (< 3 weeks) or chronic (> 3 weeks).

Initial management The vascular status of the limb must be determined quickly. The knee should be reduced immediately through gentle traction-countertraction with the patient under anesthesia. After reduction, repeat vascular examination. If the limb remains ischemic, emergent surgical exploration and revascularisation is required. If the initial vascular examination is normal, postreduction a formal angiogram should be done especially if the patient has a high velocity injury, is polytraumatized or have altered mental status. Compartment syndrome, open injury, and irreducible dislocation are other indications for emergent surgery.

Definitive management Many authors have noted superior results of surgical treatment of bicruciate injuries when compared to nonsurgical treatment. In most cases early ligament surgery (at the second or third week) seems to produce better results compared to late reconstructions. Still the management of knee dislocations remains controversial. Controversies persist regarding surgical timing, technique, graft selection, and rehabilitation. The goal of operative treatment is to retain knee stability, motion, and function.

The most common injury patterns include both cruciate ligaments and either medial collateral ligament (MCL) or lateral collateral ligament (LCL) and/or posterolateral structures. Less commonly both collateral ligaments are disrupted. Our policy has been early (from 7 to 21 days) simultaneous reconstruction of both cruciate ligaments and repairing of grade III LCL and posterolateral structures. Most acute grade III MCL tears are successfully treated with brace treatment when ACL and PCL are reconstructed early.

Most cruciate ligament injuries are midsubstance tears that need to be reconstructed with autografts or allografts. Repairs can be done in cases of bony avulsion of cruciate ligaments or grade III collateral ligament or capsular injuries. Bone-patellar tendon-bone (BPTB) autograft has mainly used in our clinics to reconstruct the ACL. In some cases BTPB allograft or hamstring tendon autografts has been used. For PCL reconstruction, BPTB allograft (11 mm in diameter) or Achilles tendon allograft has been used.

Intrasubstance grade III tears of the LCL can be repaired (in early state) but may need to be augmented with tendon allograft. The LCL and/or the popliteofibular ligament are reconstructed either with an Achilles tendon allograft, hamstring tendon autograft/allograft, tibialis anterior tendon allograft, or the BPTB allograft.

Both cruciate ligaments are reconstructed arthroscopically. The ACL tunnels are placed in the center of its anatomic insertion in tibia and in its isometric or anatomic insertion in femur. A transtibial tunnel technique for PCL reconstruction is used. The PCL tibial tunnel is drilled first under arthroscopic guidance using the PCL guide. The ACL tibial guide is drilled at least 2 cm proximal to the PCL tunnel to ensure that wide enough bone bridge remains between these tunnels. Fluoroscopy is used to ensure the right guidewire placement.

Sequence of bicruciate ligament reconstruction with BPTB grafts

Drill PCL tibial tunnel first, then ACL tibial tunnel

Drill ACL femoral tunnel, then PCL femoral tunnel

Pass PCL graft through tibial tunnel and fix in femoral tunnel

Pass ACL graft through tibial tunnel and fix in femoral tunnel

Fix PCL graft on tibia at 90° of flexion with anteromedial step off

Fix ACL graft on tibia at extension

Rehabilitation Our protocol after bicruciate ligament reconstruction with MPTB grafts has been very active. Progressive range of motion is started early after the operation with an unlocked functional brace. If simultaneous suturation of a meniscus tear has been performed, motion is limited to 60° of flexion during the first 4 weeks. Progression from partial to full weight bearing is done over the first 6 weeks. Quadriceps exercises are progressed to open-chain knee extension exercises early as well as closed-chain hamstring exercises. Brace is discontinued after 12 weeks.