Peripheral fixation of meniscal allograft does not reduce coronal extrusion under physiological load

Meniscal graft extrusion is a concern following meniscal allograft transplantation (MAT). MAT surgical techniques continue to evolve in an effort to reduce extrusion; however, improvements remain difficult to measure in vivo. A novel MRI-compatible in vitro loading device capable of applying physiologically relevant loads has been developed, allowing for the measurement of extrusion under a variety of controllable conditions. The objective of this study was to compare maximal medial MAT extrusion (1) with and (2) without an additional peripheral third point of fixation on the tibial plateau.

Twelve human cadaveric knees underwent medial MAT, utilizing soft tissue anterior and posterior root fixation via transosseous suture, with a third transosseous suture tied over a button providing peripheral fixation on the tibial plateau. The joint was positioned at 5 degrees of flexion and loaded to 1 × body weight (647.7 ± 159.0 N) during MR image acquisition, with and without peripheral fixation. The joint was then positioned at 30 degrees of flexion and the process was repeated. Maximal coronal extrusion was measured.

An increase in maximal coronal meniscal extrusion was noted between the unloaded and loaded states. At 30 degrees of flexion, with the addition of a peripheral fixation point, a statistically significant difference in absolute extrusion (p = 0.02) and relative percent extrusion (p = 0.04) between the unloaded and loaded state was found. The addition of a peripheral fixation suture resulted in an overall mean percent difference of - 2.49% (SD 14.1; 95% CI - 11.95, 6.97; n.s.) in extrusion at 5 degrees of flexion and a mean percent difference of - 0.95% (SD 7.3; 95% CI - 5.62, 3.71; n.s.) in extrusion at 30 degrees of flexion. These differences were not statistically significant.

These results suggest that the addition of a peripheral anchor in medial MAT does not reduce the amount of maximal coronal extrusion and, therefore, may not confer any clinical benefit. Surgical techniques utilized to reduce MAT extrusion need further investigation to understand if the added technical difficulty and potential expense is warranted.