Histological and Radiographic Evaluation of Equine Bone Structure after Implantation of Castor Oil Polymer.

The study investigates the effectiveness of using a plant-based polymeric biomaterial, made from castor oil, as a substitute for bone in horses.

Study Plan and Methods

• The research was conducted on six horses, with each undergoing an osteotomy (surgical cutting of the bone) on the dorsal side of both left and right third metacarpal bones (the long bone in the lower leg of the horse that typically ends in the hoof).
• One bone defect from each horse was treated with the biopolymer, while the other was left untreated, serving as a control for the study.
• The bone density of both the treated and untreated defects was monitored using radiography (X-rays) after the surgery.
• Bone biopsy samples were collected at the end of a 120-day follow-up period for further investigation.
• These biopsy fragments were analysed using light microscopy and scanning electron microscopy to examine new bone growth and the quality of bone formation.

Key Findings

• The study found that at 120 days post-surgery, mean bone density, measured in millimeters of Aluminium (mmAl), was higher in the untreated (control) defects (16.33 ± 1.6) as compared to the polymer-treated defects (14.17 ± 1.7).
• Light microscopic examination revealed an increased percentage of new bone formation in the untreated defects (50.15 ± 14.8) then in the polymer-treated ones (26.94 ± 12.1) after the same period.
• Scanning electron microscopy revealed no discernable difference in quality between existing bone and new bone formed in the presence of the biomaterial.

Conclusions

• The absence of any visible negative reactions to the biomaterial supports its biocompatibility, suggesting that it does not cause any harmful effects to the equine tissue.
• The biomaterial demonstrated osteoconducting capacity, which means it provided an environment conducive to bone regeneration and growth. Despite lower bone density and new bone formation percentage compared to the control, the new bone in the polymer-treated defects had comparable quality.
• The study concludes that the castor oil polymer shows promise as a substitute for natural bone in the treatment of bone defects in horses. This positive result could potentially lead to wider use of plant-based biomaterials in other similar applications.