Two-Dimensional Magnetic Resonance Imaging in Preparation for Autograft Anterior Cruciate Ligament Reconstruction Demonstrates Quadriceps Tendon Is Thicker Than Patellar Tendon

Effect of Quadriceps Tendon Autograft Preparation and Fixation on Graft Laxity During Suspensory Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis

Background

Favorable collagen fibril density and thickness combined with advances in graft preparation and fixation have significantly increased interest in the quadriceps tendon (QT) autograft for anterior cruciate ligament (ACL) reconstruction. While various suspensory techniques have been described, the biomechanical profile of these constructs is largely undefined.

Purpose

To compare the biomechanics of suspensory techniques for soft tissue QT autograft fixation in an in vitro model of ACL reconstruction.

Study Design

Controlled laboratory study.

Methods

Full-thickness QT grafts were harvested using a 9-mm graft blade. Adjustable-loop devices (ALDs) were secured to the graft (n = 6 per group) with a combination implant containing the ALD and suture tape-reinforced whipstitching (tape-reinforced [TR] group), tethered superficially to the graft with a whipstitch (onlay [OL] group), luggage-tagged through and around the graft (luggage tag [LT] group), or staggered behind superficial suturing (staggered [SG] group). Grafts were tested on an electromechanical testing machine following a validated in vitro reconstruction model of intraoperative workflow and postoperative ACL kinematics, cyclic loading, and load to failure.

Results

The TR group had significantly less postcyclic tension loss (mean, 24%) compared with the OL (56%; P = .002), LT (69%; P < .001), and SG (90%; P < .001) constructs. Cyclic elongation was below the 3.0-mm threshold defined as clinical failure for TR (1.6 mm), but not for OL (3.3 mm), LT (7.9 mm), and SG (11.3 mm). All constructs were within native ACL stiffness limits (220 ± 72 N/mm) without significant differences. Ultimate loads significantly exceeded a normal ACL loading limit of 454 N for TR (739 N; P = .023), OL (547 N; P = .020), and LT (769 N; P = .001), but not for SG (346 N; P = .236).

Conclusion

The TR ALD construct demonstrated the most favorable time-zero biomechanical properties of modern soft tissue QT suspensory constructs, with 32% less tension loss and 52% less cyclic elongation versus the closest construct. Failure loading of all constructs was acceptable with respect to the native ACL except for the SG group, which had suboptimal ultimate load.

Clinical Relevance

TR ALD implants may protect soft tissue QT autografts before graft-bone healing in ACL reconstruction by minimizing time-zero laxity and fixation failure.

Minimally Invasive Quadriceps Tendon Harvest for Anterior Cruciate Ligament Reconstruction Using the Quadriceps Tendon Harvest Guide (QUADTRAC) System and Repair Augmentation With a Bioinductive Implant

Quadriceps tendon autografts are an increasingly popular choice for anterior cruciate ligament (ACL) reconstruction, with decreased donor-site morbidity alongside good patient outcomes. Although harvesting of the tendon can be done in a minimally invasive fashion, this introduces some difficulty with visualization and consistency of graft sizing. The purpose of this Technical Note and video is to provide a method of quadriceps tendon autograft harvesting using the Quadriceps Tendon Harvest Guide System (QUADTRAC) in a single-bundle ACL reconstruction.