Methods: Randomized, controlled study in a laboratory setting. Blinded observations/assessment of study outcomes. Objective: The Purpose of this study is to determine the performance characteristics of Mastergraft(®) Strip with bone marrow aspirate (BMA) as a bone graft extender in a rabbit posterolateral spine fusion model.

Background: The rabbit posterolateral fusion model is an established environment for testing of fusion concepts. It offers the opportunity to obtain radiographic, histological, and biomechanical data on novel fusion materials.

Methods: Thirty six rabbits were entered into the study with 34 used for analysis. Bilateral posterolateral lumbar intertransverse fusions were performed at L5-L6. the lateral two thirds of the transverse processes were decorticated and covered with graft material: autograft only (2.5 - 3.0 cc/side), 75% Mastergraft(®) Strip + 5.0 cc BMA / 25% autograft (3.0 cc total per side), or 50% Mastergraft(®) Strip + 5.0cc BMA and 50% autograft (3.0 cc total per side). Animals were humanely euthanized at 8 weeks post surgery.

Results: The autograft group had a 60% radiographic fusion rate (6/10) and a manual palpation fusion rate of 50% (5/10). the 50% Mastergraft(®) Strip group had a 75% radiographic and manual palpation fusion rate (9/12). the 75% Mastergraft(®) Strip group demonstrated a 58% (7/12) radiographic and manual palpation fusion rate. Histologically, no adverse inflammatory reactions of significant size were present. The two Mastergraft(®) Strip groups demonstrated a tendency towards more bone development across the fusion bed.

Conclusions: In this commonly used rabbit posterolateral fusion model, Mastergraft(®) Strip with BMA in an autograft extender mode produces biomechanical and radiographic results similar to autograft fusion alone.