Length-change patterns of the medial collateral ligament and posterior oblique ligament in relation to their function and surgery

Abstract

Purpose To define the length-change patterns of the superficial medial collateral ligament (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL) across knee flexion and with applied anterior and rotational loads, and to relate these findings to their functions in knee stability and to surgical repair or reconstruction. Methods Ten cadaveric knees were mounted in a kinematics rig with loaded quadriceps, ITB, and hamstrings. Length changes of the anterior and posterior fibres of the sMCL, dMCL, and POL were recorded from 0° to 100° flexion by use of a linear displacement transducer and normalised to lengths at 0° flexion. Measurements were repeated with no external load, 90 N anterior draw force, and 5 Nm internal and 5 Nm external rotation torque applied. Results The anterior sMCL lengthened with flexion (p < 0.01) and further lengthened by external rotation (p < 0.001). The posterior sMCL slackened with flexion (p < 0.001), but was lengthened by internal rotation (p < 0.05). External rotation lengthened the anterior dMCL fibres by 10% throughout flexion (p < 0.001). sMCL release allowed the dMCL to become taut with valgus rotation (p < 0.001). The anterior and posterior POL fibres slackened with flexion (p < 0.001), but were elongated by internal rotation (p < 0.001). Conclusion The structures of the medial ligament complex react differently to knee flexion and applied loads. Structures attaching posterior to the medial epicondyle are taut in extension, whereas the anterior sMCL, attaching anterior to the epicondyle, is tensioned during flexion. The anterior dMCL is elongated by external rotation. These data offer the basis for MCL repair and reconstruction techniques regarding graft positioning and tensioning.

The medial ligaments and the ACL restrain anteromedial laxity of the knee

“…The importance of the dMCL in the control of tibial external rotation might be unexpected, in view of its relatively small size and its failure strength being less than that of the sMCL [23]. However, we have found that the fibres of the dMCL are oriented antero-distally from the femur when the tibia is externally rotated, and are obviously stretched by that motion [35] (Fig. 1).…”

The bone attachments of the medial collateral and posterior oblique ligaments are defined anatomically and radiographically

“…In contrast, one study [20] described the centre of the femoral sMCL attachment 5 mm posterior and 3 mm proximal to the ME, which is outside the mean limit of the attachment area in the present study. The exact femoral attachment site is important: if a graft is placed posteriorly it will slacken with knee flexion [34], or could be too tight in extension. The centre of the femoral attachment of the sMCL is at the same distance from the distal and posterior surfaces of the medial femoral condyle, which suggests that a reconstruction placed on the ME will be isometric.…”

“…and over-constraint of the knee, or an insufficient and loose reconstruction, across the arc of knee motion [3,35]. There are significant differences of isometry, or length-change behaviour, across the widths of each of the medial ligaments [34], so it is apparent that accurate positioning is important if the normal patterns of restraint are to be reproduced.…”

O Complexo Medial do Joelho: o Lado que Caiu em Esquecimento

“…Na prática clínica a designação ligamento colateral medial é utilizada para identificar o ligamento colateral superficial (LCMs), sendo este a estrutura mais frequentemente lesionada após trauma do joelho. [1][2][3][4][5] Ele pertence a uma unidade ligamentar, miotendinosa e meniscal cujos elementos funcionam em sinergia: complexo medial do joelho (CMJ).…”

“…No entanto, sublinhamos que o LCA é o principal estabilizador da RI. 2,6 Já face a forças de rotação externa (RE), o LCMp e o LCMs são os estabilizadores principais em todo o arco, e LOP contribui em extensão. 2,4,6,9 O SM, ao promover a RI da tíbia e ao tensionar estruturas do CPM com a flexão do joelho, torna-se num estabilizador dinâmico face a forças de RE e de translação anterior da tíbia.…”