Medial Collateral Ligament Reconstruction: A Gracilis Tenodesis for Anteromedial Knee Instability

An anteromedial stabilization procedure has the most protective effect on the anterior cruciate ligament in tibial external rotation. A human knee model study

INTRODUCTION

Anterior cruciate ligament (ACL) reconstruction remains associated with the risk of re-rupture and persisting rotational instability. Additional extraarticular anterolateral stabilization procedures stabilize the tibial internal rotation and lead to lower ACL failure rate and improved knee stability. However, data for additional stabilization of tibial external rotation is lacking and the importance of an anteromedial stabilization procedure is less well evaluated. Aim of this study is to investigate the influence of an extraarticular anteromedial stabilization procedure for the stabilization of the tibial external rotation and protection of the ACL from these rotational forces.

METHODS

Internal and external rotations of the tibia were applied to a finite element (FE) model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Five additional anatomic structures (Anteromedial stabilization/anteromedial ligament, AML, augmented superficial medial collateral ligament, sMCL, posterior oblique ligament, POL, anterolateral ligament, ALL, and popliteal tendon, PLT) were added to the FE model separately and then combined. The force histories within all structures were measured and determined for each case.

RESULTS

The anteromedial stabilization or imaginary AML was the main secondary stabilizer of tibial external rotation (90% of overall ACL force reduction). The AML reduced the load on the ACL by 9% in tibial external rotation which could not be achieved by an augmented sMCL (-1%). The AML had no influence in tibial internal rotation (-1%). In the combined measurements with all additional structures (AML, ALL, PLT, POL) the load on the ACL was reduced by 10% in tibial external rotation.

CONCLUSION

This study showed that an additional anteromedial stabilization procedure secures the tibial external rotation and has the most protective effect on the ACL during these external rotational forces.

Single-Strand "Short Isometric Construct" Medial Collateral Ligament Reconstruction Restores Valgus and Rotational Stability While Isolated Deep MCL and Superficial MCL Reconstruction Do Not

BACKGROUND

Historical MCL (medial collateral ligament) reconstruction (MCLR) techniques have focused on the superficial MCL (sMCL) to restore valgus stability while frequently ignoring the importance of the deep MCL (dMCL) in controlling tibial external rotation. The recent recognition of the medial ligament complex importance has multiple studies revisiting medial anatomy and questioning contemporary MCLR techniques.

PURPOSE

To assess whether (1) an isolated sMCL reconstruction (sMCLR), (2) an isolated dMCL reconstruction (dMCLR), or (3) a novel single-strand short isometric construct (SIC) would restore translational and rotational stability to a knee with a dMCL and sMCL injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Biomechanical testing was performed on 14 fresh-frozen cadaveric knee specimens using a custom multiaxial knee activity simulator. The specimens were divided into 2 groups. The first group was tested in 4 states: intact, after sectioning the sMCL and dMCL, isolated sMCLR, and isolated dMCLR. The second group was tested in 3 states: intact, after sectioning the sMCL and dMCL, and after single-strand SIC reconstruction (SICR). In each state, 4 loading conditions were applied at 0°, 20°, 40°, 60°, and 90° of knee flexion: 8-N·m valgus torque, 5-N·m external rotation torque, 90-N anterior drawer, and combined 90-N anterior drawer plus 5-N·m tibial external rotation torque. Anterior translation, valgus rotation, and external rotation of the knee were measured for each state and loading condition using an optical motion capture system.

RESULTS

sMCL and dMCL transection resulted in increased laxity for all loading conditions at all flexion angles. Isolated dMCLR restored external rotation stability to intact levels throughout all degrees of flexion, yet valgus stability was restored only at 0° of flexion. Isolated sMCLR restored valgus and external rotation stability at 0°, 20°, and 40° of flexion but not at 60° or 90° of flexion. Single-strand SICR restored valgus and external rotation stability at all flexion angles. In the combined anterior drawer plus external rotation test, isolated dMCL and single-strand SICR restored stability to the intact level at all flexion angles, while the isolated sMCL restored stability at 20° and 40° of flexion but not at 60° or 90° of flexion.

CONCLUSION

In the cadaveric model, single-strand SICR restored valgus and rotational stability throughout the range of motion. dMCLR restored rotational stability to the knee throughout the range of motion but did not restore valgus stability. Isolated sMCLR restored external rotation and valgus stability in early flexion.

CLINICAL RELEVANCE

In patients with anteromedial rotatory instability in the knee, neither an sMCLR nor a dMCLR is sufficient to restore stability.

Editorial Commentary: Don't Neglect the Medial Side of the Knee in Patients With Anterior Cruciate Ligament Injury

The medial collateral ligament (MCL) of the knee, as well as the posteromedial complex (including the posterior oblique ligament [POL] and ramp lesions of the meniscus) is often considered the "neglected" ligament or corner because of the belief that these anatomic structures have enormous regenerative potential and therefore hardly ever need surgical treatment. In patients with anterior ligament cruciate (ACL) tears, the overall combined prevalence of MCL (superficial [sMCL] and deep [dMCL]) and isolated dMCL injuries is high (16.5% + 24.8% = 41.3%). In terms of the POL, with a restraint to both internal tibial rotation and valgus rotation during extension, I have some doubts regarding its role in anteromedial instability (AMRI). In fact, AMRI of the knee is caused mainly by injury to both the ACL and the MCLs, resulting in coupled anterior tibial translation and external rotation, causing the medial tibial plateau to subluxate anteriorly. The sMCL provides the most substantial restraint, and the dMCL and POL play more minor roles. Finally, in ACL-deficient knees, ramp lesions are prevalent (9.3%-24.0%), and failing to identify and treat these lesions results in knee instability. In my experience, all unstable ramp lesions should be repaired. In ACL-deficient knees in patients with a tibial slope >5°, an occult ramp lesion should be strongly suspected. In summary, the medial compartment of the knee is complex and encompasses many structures (MCL, POL, ramp, tibial slope), and I believe that we will increasingly move toward individualized treatment.

[Injuries of the medial side of the knee : When and how should they be treated?]

Different medial structures are responsible for restraining valgus rotation, external rotation, and anteromedial rotation. When injured this can result in various degrees of isolated and combined instabilities. In contrast to earlier speculation, the posterior oblique ligament (POL) is no longer considered to be the main stabilizer of anteromedial rotatory instability (AMRI). Acute proximal medial ruptures are typically managed conservatively with very good clinical results. Conversely, acute distal ruptures usually require a surgical intervention. Chronic instabilities mostly occur in combination with instabilities of the anterior cruciate ligament (ACL). The clinical examination is a particularly important component in these cases to determine the indications for surgery for an additional medial reconstruction. In cases of severe medial and anteromedial instabilities, surgical treatment should be considered. Biomechanically, a combined medial and anteromedial reconstruction appears to be superior to other reconstruction methods; however, there is currently a lack of clinical studies to confirm this biomechanical advantage.

Anatomic Flat Double-Bundle Medial Collateral Ligament Reconstruction

Several surgical techniques have been described to restore the anatomy of the medial collateral ligament, involving suture repair and reconstruction, with the latter having been associated with superior postoperative outcomes. Recently, a growing interest in anatomic isometric medial collateral ligament reconstruction (MCLR) has been developed, involving careful evaluation and finding the most appropriate location for the femoral placement of the allograft. Therefore, the purpose of this article is to describe anatomic MCLR aiming to restore medial knee stability by focusing on isometric positions within the native anatomy of the MCL.

Reduction of Collision Risk in Multi-ligament Knee Injury KD-III-M and KD-IV Surgery-Superficial Medial Collateral Ligament Reconstruction with Suture Anchors

Surgical reconstruction of the medial collateral ligament (MCL) can be challenging during multi-ligament knee injury surgery due to the limited working space. There is risk of collision between the guide pin, pulling sutures, reamer, tunnel, implant, and graft of the different ligament reconstructions. In this Technical Note, we detail our senior author's technique for superficial MCL reconstruction using suture anchors and cruciate ligament reconstruction with all-inside techniques. The technique mitigates the risk of collision by confining the reconstruction process and implants for MCL fixation on the medial femoral condyle and medial proximal tibia.

Instabilität des Kniegelenks – medial oder anteromedial?

Hintergrund

Verletzungen des medialen Bandkomplexes gehören zu den häufigsten Knieverletzungen. Sie heilen zwar meist mit konservativer Therapie problemlos aus, persistierende Instabilitäten erhöhen aber die Belastung der Kreuzbänder und benötigen speziell bei deren Beteiligung eine adäquate Therapie.

Anatomie und Biomechanik

Der mediale Seitenbandkomplex besteht im Wesentlichen aus dem oberflächlichen Seitenband (sMCL), welches der primäre Stabilisator gegen Valgus ist, dem tiefen Seitenband (dMCL) mit dessen schräg verlaufendem ventralem Anteil (AML), die nur sekundäre Stabilisatoren gegen Valgus darstellen, aber primär gegen Außenrotation stabilisieren, und dem hinteren Schrägband (POL), das in vollständiger Streckung gegen Valgus sowie gegen Innenrotation stabilisiert.

Therapie

Chronische Instabilitäten bzw. höhergradige Verletzungen mit Dislokation der Bandstümpfe oder multiligamentäre Verletzungen bedürfen einer operativen Versorgung. Im Akutstadium zeigen Avulsionsverletzungen bei anatomischer Refixation gutes Heilungspotenzial, während bei intraligamentären Verletzungen zusätzlich zur Naht der Bandanteile eine Augmentation mit Sehnenmaterial empfohlen wird. Bei chronischen Instabilitäten ist die Differenzierung des Instabilitätsmusters ausschlaggebend für die Wahl der Rekonstruktionstechnik (reine sMCL-Rekonstruktion oder kombinierte Rekonstruktion von sMCL und AML). In beiden Fällen kommt die hier beschriebene Technik mit flachem Transplantat der Anatomie näher als bei konventionellen Verfahren.

Diskussion

Rekonstruktionstechniken unter Verwendung flacher Sehnentransplantate, die alle betroffenen Bandanteile adressieren, haben sich biomechanisch als sehr effektiv erwiesen, komplexe mediale Instabilitäten suffizient zu behandeln. Ob diese auch klinisch überlegen sind, werden zukünftige klinische Studien zeigen müssen.