In situ forces in the posterolateral structures of the knee under posterior tibial loading in the intact and posterior cruciate ligament‐deficient knee

Abstract

The posterolateral structures of the knee consist of a complex anatomical architecture that includes several components with both static and dynamic functions. Injuries of the posterolateral structures occur frequently in conjunction with ruptures of the posterior cruciate ligament. To investigate the role of the posterolateral structures in maintaining posterior knee stability, we measured the in situ forces in the posterolateral structures and the distribution of force within the structures' major components, i.e., the popliteus complex and the lateral collateral ligament, in response to a posterior tibial load. Eight cadaveric knees were tested. With use of a robotic/universal force-moment sensor testing system, a posterior tibial load of 110 N was applied to the knee, and the resulting five-degree-of-freedom kinematics were measured at flexion angles of 0, 30, 60, 75, and 90 degrees. The knees were tested first in the intact state and then after the posterior cruciate ligament had been resected. These tests were also performed with an additional load of 44 N applied at the aponeurosis to simulate contraction of the popliteus muscle. In the intact knee, the in situ forces in the posterolateral structures were found to decrease with increasing knee flexion. After the posterior cruciate ligament was sectioned, these forces increased significantly at all angles of flexion. With no load applied to the popliteus muscle, the in situ forces in the popliteus complex were similar to those in the lateral collateral ligament. However, with a load of 44 N applied to the popliteus muscle, in situ forces in the popliteus complex were three to five times higher than those in the lateral collateral ligament. These results reveal that in response to posterior tibial loads, the posterolateral structures play an important role at full extension in intact knees and at all angles of flexion in posterior cruciate ligament-deficient knees. The popliteus muscle appears to be a major stabilizer under this loading condition; thus, the inability to restore its function may be a cause of unsatisfactory results in reconstructive procedures of the posterolateral structures of the knee.

Double-bundle PCL and Posterolateral Corner Reconstruction Components are Codominant

“…Contributing to the unsatisfactory results from PCL reconstruction is the failure to address associated injuries to supporting structures such as those of the posterolateral corner (PLC) of the knee [6,8,18,25]. Numerous studies describe the importance of these structures and their synergistic relationship with the PCL in controlling knee translation and rotation [15,17,22,30,32]. In addition, failure to treat injuries to the PLC places the knee at risk for continued instability and development of premature degenerative arthritis, even with a surgically reconstructed PCL [12,15,25,30].…”

“…This study also showed that double-bundle PCL reconstruction alone, without simultaneous reconstruction of the PLC, may result in significant increases in posterior tibial translation, external tibial rotation, and in situ forces in the PCL grafts. The ability of a PLC reconstruction to limit external tibial rotation and affect forces in a PCL graft in response to various loading conditions has been studied [13,15,17,20,21,28]. All previous studies, however, have reported the effects of the loading conditions on the PCL or PLC as a whole, without focusing attention on the specific components of the reconstruction.…”

Role of High Tibial Osteotomy in Chronic Posterior Cruciate Ligament and Posterolateral Corner Knee Instability

“…Soft tissue effects occur mainly on ACL, which presents a decrease in number, diameter and density of collagen fibers (Ochi et al, 1999) and on PLC. Indeed, forces on PLC increase from 34±25N with PCL to 63±24N without PCL at 30° of knee flexion and from 38±46N with PCL to 86±53N without PCL at 90° of knee flexion (Hoher et al, 1998).…”

Posterolaterale Rekonstruktion des Kniegelenks nach Larson

“…Die wichtigsten Strukturen der posterolateralen Gelenkecke sind das Ligamentum collaterale laterale (LCL), der mit der Gelenkkapsel verwachsene Kopf des lateralen Musculus gastrocnemius (Polkappe), das Ligamentum popliteum obliquum, das Ligamentum popliteum arcuatum, das Ligamentum popliteofibulare und die Ansatzsehne des Musculus popliteus [1-4, 8, 9, 11, 13, 15, 16, 19, 20] (Abbildung 1a). Die posterolaterale Gelenkecke und das HKB sichern das Kniegelenk gegen posteriore Translation und gegen Außenrotation [5,6,12,14,[21][22][23]. Somit führt eine Verletzung oder Insuffizienz der posterolateralen Strukturen zu einer posterolateralen Rotationsinstabilität.…”

“…Nach frischer Verletzung der posterolateralen Stabilisatoren sollte versucht werden, eine anatomische Naht durchzuführen. Hierbei sind insbesondere das LCL und die Sehne des Musculus popliteus zu berücksichtigen [5,6,12,14,17,[21][22][23]. Die Orientierungen der Insertionen des LCL und der posterolateralen Stukturen unterscheiden sich in Extension und 90° Flexion des Kniegelenks (Abbildungen 1a bis 1c).…”