Biomechanical Properties of a Bone Plug Versus Soft Tissue Allograft for Medial Meniscus Root Fixation and the Effect of Peripheral Stabilization

Abstract

Background:

Root fixation for medial meniscal transplantation can be performed with or without bone plugs. Bone plug fixation has generally been shown to have superior time-zero biomechanical characteristics. Little is known about the biomechanics of peripheral stabilization for meniscal allograft transplantation (MAT) and its ability to improve time-zero biomechanics.

Purpose/Hypothesis:

The purpose was to compare the biomechanical effectiveness of modern soft tissue (ST) root fixation versus bone plug (BP) root fixation as well as peripheral stabilization in MAT. The hypothesis was that, while BP root fixation likely has better time-zero biomechanical characteristics with regard to contact forces and laxity, the addition of peripheral stabilization would mitigate these differences for either type of root fixation in a cadaveric model.

Study Design:

Controlled laboratory study.

Methods:

A total of 8 matched-pair cadaveric knees with a mean age of 55 ± 10 years (5 female and 3 male) were used. The knees were tested in the following states: intact, meniscectomy, MAT (with either BP or ST root fixation) with peripheral stabilization, and MAT (with either BP or ST root fixation) without peripheral stabilization. Medial tibiofemoral joint contact area and pressure as well as knee laxity for anterior-posterior tibial translation, external-internal rotation, and varus-valgus were quantified at 0°, 30°, 60°, and 90° of knee flexion. A paired t test with a significance level at .05 was used for statistical analysis.

Results:

There were small but significant differences between ST and BP MAT with or without peripheral stabilization in contact forces and most laxity measurements. While both groups demonstrated improved stability with peripheral stabilization, the BP MAT group exhibited greater influence from stabilization in laxity with internal-external rotation (P = .010), contact area with internal-external rotation (P = .022), and contact area with varus (P < .005).

Conclusion:

This study demonstrated the slight superiority of BP versus ST root fixation and that the addition of peripheral stabilization for ST and BP MAT decreased medial tibiofemoral joint contact pressure and increased medial tibiofemoral joint contact area at time zero. While the time-zero biomechanical characteristics of BP MAT were more influenced by peripheral stabilization than the ST technique, this is most likely because of graft size mismatch.

Clinical Relevance:

With current root fixation devices, both ST and BP MAT had generally similar biomechanical characteristics at time zero, and peripheral stabilization seemed to improve both modes of fixation.