The potential use of tetracalcium phosphate in vertebral augmentation: A study in a sheep model

Percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) are widely used to treat vertebral frac-tures. However, the standard filler material, polymethylmethacrylate (PMMA), presents significant drawbacks, including thermal dam-age, allergic reactions, and poor biocompatibility. Tetracalcium phosphate (TTCP), a calcium phosphate cement (CPC), has emerged as a promising alternative due to its superior biocompatibility, osteoconductivity, and ability to integrate with natural bone. This study aimed to evaluate the feasibility of TTCP for vertebral augmentation in a preclinical sheep model, focusing on biomechanical stability, biocompatibility, and osteogenic potential.

Five Akkaraman sheep underwent PKP with TTCP at three lumbar vertebral levels (L2-L4). Under general anesthesia, TTCP cement was injected into cavities prepared according to the standard PKP procedure. Postoperative care included analgesia and antibiotics. Four animals were followed for 12-14 weeks, and one for 25 weeks. At the end of the study period, the animals were euthanized and vertebrae were harvested for biomechanical testing using a Shimadzu AG-IS 100 kN machine. Histological evaluation was performed to assess ossification stages according to Shapiro's classification. Statistical analysis was conducted using paired t-tests (p<0.05).

One animal was euthanized prematurely due to infection, while four completed the study without complications. Biomechanical analysis demonstrated no significant difference in compressive strength between treated and untreated vertebrae (p>0.05). Histological examination revealed osteoblastic activity, progressive mineralization, and successful bone integration.

TTCP demonstrated promising biomechanical and biophysiological properties for vertebral augmentation. However, its use in infected sites and in the presence of metabolic bone disorders may be limited. Further clinical studies are required to validate its long-term efficacy.