Dynamics of acute-phase and endothelial responses and immune complex development during bone replacement of bone fragment fractures in dogs using germanium-doped calcium-phosphate ceramics

Abstract

Fragmentary bone fractures are associated with a higher rate of postoperative morbidity because of bone defect
formation. Therefore, bone replacement, specifically doped calcium-phosphate ceramics, is required to restore
bone structure and function. This study aims to biochemically evaluate acute-phase and endothelial responses, as
well as immunological complex development, after bone replacement of bone fragment fractures in dogs using
germanium-doped calcium-phosphate ceramics. Plate osteosynthesis was used on dogs with long tubular bone
fragment fractures. Bone defects in the experimental group (n = 10) were filled with germanium-doped calcium-
phosphate ceramics (H/-TCP/l-Gе-700), whereas those in the control group (n = 10) were left unfilled. following
the injury and again 3, 7, 14, 30, and 60 days following osteosynthesis, blood samples were collected. Recovery
of limb function was 1.3 times quicker (P 0.001) and complete recovery was 1.2 times faster (P 0.01) in the
experimental group compared to the control. Bone regenerate in the control animals did not have adequate density
and had a strong periosteal response, whereas in the experimental animals the defect was filled with a regenerate
of high X-ray density on day 60. Albumin and total protein levels were similarly within the normal range in both
samples. Protein C activity in the experimental group was 1.3% higher (P 0.001) on day 3, and 2% higher (P
0.001) on day 7 compared to the control group, before returning to baseline by day 14. By day 60, the concentration
of ceruloplasmin in the experimental mice had returned to normal after initially being 1.1-fold ( 0.001) greater
than in the control animals. After injury, small molecular circulating immune complexes (CIC) increased 1.1-fold
( 0.001), peaking on day 14 for both the control and experimental groups. By day 60, the CIC level in the
experimental group had returned to pre-injury levels. Nitric oxide (NO) levels rose from day 3 to day 30 (with a
high on day 7) in the experimental group and from day 7 to day 60 (with a peak on day 30) in the control group.
When fragments of long tubular bones are implanted with calcium-phosphate ceramics doped with geranium, the
inflammatory-resorptive stage of reparative osteogenesis is mildly suppressed and the proliferative stage is
strongly stimulated.