Medial Collateral Ligament Reconstruction for Anteromedial Instability of the Knee: A Biomechanical Study In Vitro

Abstract

Background: Although a medial collateral ligament (MCL) injury is associated with anteromedial rotatory instability (AMRI) and often with an anterior cruciate ligament (ACL) injury, there has been little work to develop anteromedial (AM) reconstruction to address this laxity. Purpose: To measure the ability of a novel “anatomic” AM reconstruction technique to restore native knee laxity for isolated AM insufficiency and combined AM plus posteromedial insufficiency. Study Design: Controlled laboratory study. Methods: A total of 12 cadaveric knees were mounted in a kinematic testing rig that allowed the tibia to be loaded while the knee flexed-extended 0° to 100° with 88-N anteroposterior translation, 5-N·m internal rotation–external rotation (ER), 8-N·m valgus, and combined anterior translation plus ER to simulate AMRI. Joint motion was measured using optical trackers with the knee intact, after superficial MCL (sMCL) and deep MCL (dMCL) transection, and after AM reconstruction of the sMCL and dMCL with semitendinosus autografts. The posteromedial capsule (PMC)/posterior oblique ligament (POL) was then transected to induce a grade 3 medial injury, and kinematic measurements were repeated afterward and again after removing the grafts. Laxity changes were examined using repeated-measures analysis of variance and post-testing. Results: sMCL and dMCL deficiency increased valgus, ER, and AMRI laxities. These laxities did not differ from native values after AM reconstruction. Additional PMC/POL deficiency did not increase these laxities significantly but did increase internal rotation laxity near knee extension; this was not controlled by AM reconstruction. Conclusion: AM reconstruction eliminated AMRI after transection of the dMCL and sMCL, and also eliminated AMRI after additional PMC/POL transection. Clinical Relevance: Many MCL injuries occur in combination with ACL injuries, causing AMRI. These injuries may rupture the AM capsule and dMCL. Unaddressed MCL deficiency leads to an increased ACL reconstruction failure rate. A dMCL construct oriented anterodistally across the medial joint line, along with an sMCL graft, can restore native knee ER laxity. PMC/POL lesions did not contribute to AMRI.

A Triple-Strand Anatomic Medial Collateral Ligament Reconstruction Restores Knee Stability More Completely Than a Double-Strand Reconstruction: A Biomechanical Study In Vitro

“…Although the sMCL and dMCL are the main medial restraints to AMRI, 5 it is necessary to confirm that an sMCL + dMCL reconstruction will be effective in such a situation. 30 The POL needs consideration only in the relatively uncommon scenario of PMRI and/or excess hyperextension attributed to the MCL injury that also involves the posterior cruciate ligament and posterior capsule. Avoiding unnecessary surgery is desirable to save medical resources and reduce costs as well as morbidity.…”

Medial Collateral Ligament Tear

“…Although several methods exist, the three primary types of medical collateral ligament reconstruction are single-bundle anatomic, double-bundle nonanatomic, and double-bundle anatomic. For those patients who present with significant valgus malalignment, a two-stage procedure with distal femur osteotomy, followed by reconstruction, is likely most appropriate (Athwal et al, 2020; Encinas-Ullán & Rodríguez-Merchán, 2018; Helal et al, 2022; LaPrade et al, 2007; Laprade & Wijdicks, 2012; Miyaji et al, 2022; Ohliger et al, 2022; Ren et al, 2017; Wijdicks et al, 2010).…”

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

“…The lack of attention to rotatory stability is reflected in the multitude of surgical reconstruction techniques that have been developed to restore valgus stability, 10,18,21,24,46 usually with a superficial medial collateral ligament (sMCL) limb, while only recently have reconstructions included a deep MCL (dMCL) limb to restore rotatory stability. 5,20,26,40 While the MCL is the most injured ligament of the knee, surgical techniques for its repair and reconstruction have received less attention than the cruciate ligaments and the posterolateral corner, likely as a result of its excellent healing potential in the isolated setting. 8,12,13,25,29,31,38 This has begun to change, as multiple recent studies have highlighted the increased anterior cruciate ligament (ACL) rerupture rate if medial-sided instability is not addressed at the time of ACL reconstruction (ACLR), likely due to increased forces on the ACL graft.…”

“…In response, 2 novel techniques have been described, including an sMCL limb combined with a dMCL or ''anteromedial'' limb, which have successfully restored valgus and rotational stability. 5,26 While these constructs represent significant advances in the treatment of medial-sided knee injuries, the authors of this study wished to assess whether the same results could be accomplished using a single-strand construct in an effort to decrease the costs, the chances of tunnel convergence, and the complexity of surgical technique. 6,11 The decision was made to focus on the most common injury pattern noted in the clinical setting: an injury to the dMCL and sMCL with the POL remaining intact.…”