The Effects of Grade III Posterolateral Knee Complex Injuries on Anterior Cruciate Ligament Graft Force

Abstract

To determine if untreated grade III injuries of the posterolateral structures contribute to increased force on an anterior cruciate ligament graft, we measured the force in the graft in cadaveric knees during joint loading after reconstruction with otherwise intact structures and in the same reconstructed knees after selected cutting of specific posterolateral knee structures. Tests were first performed on the knee with the posterolateral structures intact and then after sequential sectioning of the fibular collateral ligament, popliteofibular ligament, and popliteus tendon. The graft force was significantly higher after fibular collateral ligament transection during varus loading at both 0 degree and 30 degrees of knee flexion than it was for the same loading of the joint with intact posterolateral structures. In addition, coupled loading of varus and internal rotation moments at 0 degree and 30 degrees of flexion further increased graft force beyond that with varus force alone. The increase in graft force remained significant with additional sequential cutting of the popliteofibular ligament and popliteus tendon. We believe this study supports the clinical observation that untreated grade III posterolateral structure injuries contribute to anterior cruciate ligament graft failure by allowing higher forces to stress the graft.

Anatomy of the posterolateral aspect of the goat knee

“…We chose to study the goat posterolateral knee further, because although we were able to create a posterolateral knee instability model in the rabbit, 11 we believe the rabbit model is too small to perform in vivo verification of the effects of posterolateral knee instability on anterior or posterior cruciate ligament reconstructions. 4,5 In addition, goats are noted to have locomotion and activity patterns which are greater than cage-confined rabbits.…”

“…[1][2][3][4][5][6][7][8][9] It has been well documented that the fibular collateral ligament, popliteus tendon, and popliteofibular ligament are the primary stabilizers to abnormal varus, external rotation, and coupled posterolateral rotation for the human knee. 1,2,10 However, in vivo studies on animal models, other than the rabbit, 11 demonstrating the natural history of injuries to the posterolateral aspect of the knee have not yet been performed.…”

Anatomic Posterolateral Corner Reconstruction

“…9 Chronic posterolateral instability has also been shown to increase forces on the ACL and PCL, which can potentially lead to graft failure in the setting of multiligament injury. [10][11][12] Historically, both repair and reconstruction have been used for treating PLC tears. PLC repairs have been reported to have a higher reoperation rate when compared with reconstructive techniques.…”

Can Stress Radiography of the Knee Help Characterize Posterolateral Corner Injury?

“…Delay in diagnosis complicates surgical treatment, rendering repair less reliable and more difficult, with excessive scar tissue potentially concealing vital ligamentous, capsular, and neurovascular structures [3,14,17,18,23,24]. Deficiency of the PLC generates excessive force on anterior cruciate ligament (ACL) [15] and posterior cruciate ligament (PCL) [14] grafts, and unrecognized injury is associated with failure of cruciate reconstruction [21].…”