A Retensionable Inlay/Onlay Hybrid Double-Bundle Medial Collateral Ligament Reconstruction Produces Superior Restoration of the Uninjured State When Compared to a Single-Bundle Inlay Reconstruction.

BACKGROUND

Traditional superficial medial collateral ligament (sMCL) reconstruction techniques have not consistently restored native laxity.

PURPOSE/HYPOTHESIS: The purpose of this study was to develop a retensionable inlay/onlay hybrid medial collateral ligament (MCL) reconstruction through comparison to a biomechanically and clinically validated reconstruction. It was hypothesized that increasing the distal footprint on the tibia through a double-bundle construct and a retensionable construct would better restore native laxity.

STUDY

DESIGN

Controlled laboratory study.

METHODS

A total of 27 cadaveric knees were tested on a 6 degrees of freedom robot system. Knees were tested with valgus and external rotation (ER). Each knee was tested in a native state and an injured state after sectioning of the sMCL. One of 3 reconstructions using an anterior tibialis allograft was then performed: (1) single-bundle inlay reconstruction, (2) double-bundle inlay/onlay hybrid reconstruction with tibial fixation at both the proximal and distal (PD) tibial insertions of the sMCL footprint, or (3) double-bundle inlay/onlay hybrid reconstruction with tibial fixation at the anterior and posterior (AP) aspects of the distal sMCL tibial insertion. The constructs used retensionable variable-loop devices, allowing for retensioning after knee cycling. The constructs were tested after cycling and retensioning.

RESULTS

Sectioning of the sMCL resulted in significantly increased laxity compared to the native state for both valgus and ER laxity testing (P < .001). After flexion cycling and subsequent retensioning, both AP and PD double-bundle reconstructions demonstrated significantly higher restoration of stability compared to cycled single-bundle reconstructions (P < .001). Both double-bundle reconstructions were significantly closer to the native state than the single-bundle reconstruction for valgus rotation (P < .001) and ER (P < .05). For valgus testing, there was no difference between retensioned double-bundle constructs and the native state, with a pooled valgus difference of 0.56° (95% CI, 0.05°-1.06°; P = .032). For ER testing, no differences were found between the retensioned AP double-bundle and the native state (P = .836), suggesting more complete restoration was achieved by AP double-bundle restoration.

CONCLUSION

A retensionable inlay/onlay hybrid double-bundle MCL reconstruction with a larger femoral footprint and 2 distal anterior-posterior tibial footprints produced superior restoration of the uninjured state when compared to a traditional single-bundle inlay reconstruction. For double-bundle reconstructions, an anterior-posterior tibial fixation achieved mean values closer to the native state than proximal-distal fixation.

CLINICAL RELEVANCE: A double-bundle retensionable inlay/onlay hybrid reconstruction is an effective alternative to a single-bundle inlay reconstruction technique. The double-bundle reconstruction may better withstand early unrestricted range of motion during postoperative phases.