Assessment of SiCaP-30 in a Rabbit Posterolateral Fusion Model with Concurrent Chemotherapy

Chemotherapy derivatives of the rabbit posterolateral fusion model are considered a challenging environment in which to test bone graft materials. The purpose of this study was to determine the performance characteristics of SiCaP-30 as a bone graft substitute relative to autograft (iliac crest bone graft [ICBG]), Actifuse ABX and β-Tricalcium Phosphate-Bioactive Glass-Type I Collagen (βTCP-BG) in a rabbit posterolateral spine fusion model with concurrent chemotherapy treatment This was a randomized, controlled study in a laboratory setting with blinded assessment of fusion by manual palpation and flexibility testing. Sixty rabbits were entered into the study with 45 used for analysis. Chemotherapeutic agents, doxorubicin and cis-platin (2.5 mg/kg), were administered one week prior to surgery, and one, two and three weeks post surgery. Bilateral posterolateral lumbar intertransverse process fusions were performed at L5-L6. The lateral two thirds of the transverse processes were decorticated and covered with 3cc/side of one of the following graft materials: autologous ICBG, Actifuse ABX (ApaTech Ltd, UK), Vitoss BA (Orthovita, USA) or SiCaP-30 (ApaTech Ltd., UK). Animals were euthanized 12 weeks post surgery. The ICBG group had a 45% (5/11) manual palpation fusion rate and correlated with motion analysis fusion results of 36% (4/11). The Actifuse ABX group had a 33% (4/12) manual palpation fusion rate and a motion analysis fusion rate of 25% (3/12). No motion segments in the Vitoss BA group (0/11) showed any signs of fusion. The SiCaP-30 group demonstrated a statistically higher manual palpation and motion analysis fusion rate of 82% (9/11; p<0.05) and produced superior bone formation compared with Actifuse ABX and βTCP-BG.