This document summarizes a study measuring bone growth on bioactive implants. Histological slides of implants with bone growth were analyzed to assess bone ingrowth percentage and bone coverage using standard measurement techniques. The results showed silicon-substituted hydroxyapatite implants had 11% more bone ingrowth and 31% more bone coverage than hydroxyapatite implants alone. Literature references suggest silicon increases hydroxyapatite solubility and the rate of bone apposition to the implant surface.

1. Aravind Baskar | A0136344 | ME 6505 | October 20, 2015
Measurement of
Bone growth on a
Bioactive Implant
ENGINEERING MATERIALS IN MEDICINE

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PROJECT DESCRIPTION:
In this assignment, the group is asked to study histological slides of bioactive implants into which bone has grown, and
the group is required to assess how much bone integration has occurred, using standard measurement techniques.
PERCENTAGE OF BONE INGROWTH
Quadrant Line HBI AZBI Average Quadrant Line HBC AZBI Average
1 1 1 1
2 1 2 2
3 1 3 1
4 1 4 2
5 0 5 1
6 1 6 1
7 1 7 0
1 0 1 2
2 3 2 1
3 1 3 0
4 0 4 1
5 2 5 1
6 0 6 0
7 2 7 4
1 0 1 2
2 2 2 2
3 3 3 3
4 1 4 1
5 3 5 5
6 1 6 1
7 4 7 2
1 1 1 4
2 1 2 2
3 1 3 5
4 0 4 4
5 1 5 2
6 3 6 3
7 1 7 0
21%
III 33% III 38%
Percentage of bone ingrowth
Micrograph - I Micrograph - II
I 14%
21%
I 19%
32%
II
IV 19% IV 48%
19% II

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COVERAGE OF BONE ON IMPLANT SURFACES
RESULTS & DISCUSSION:
From the literature study it is understood that Si-HA has a better bone apposition rate than HA. From the results obtained
it is inferred that the graphs I & III belong to HA and graphs II & IV belong to Si-HA. Percentage of change of Si-HA from
HA in bone ingrowth is about 11% and in bone coverage it is 31%. Therefore, over time, a Si-HA implant will have
significantly better as well as faster bonding with the human system than a HA implant. Ref. text is as follows: “The
quantitative histomorphometry results indicate that the percentage of bone ingrowth for Silicon-substituted hydroxyapatite
(Si-HA) was significantly greater than that for phase pure hydroxyapatite (HA). In addition, the percentage of bone/implant
Quadrant Line HBC HIS ZBC Average Quadrant Line HBC HIS ZBC Average
1 1 9 1 6 1
2 2 8 2 3 0
3 2 2 3 2 1
4 2 6 4 3 0
5 1 3 5 5 0
6 2 1 6 5 1
1 4 3 1 1 0
2 6 1 2 3 0
3 3 4 3 3 0
4 5 1 4 1 0
5 2 3 5 4 1
6 3 2 6 4 0
1 3 1 1 2 0
2 3 2 2 3 1
3 2 1 3 3 1
4 5 2 4 1 3
5 3 3 5 1 0
6 3 2 6 0 1
1 2 3 1 6 1
2 2 2 2 6 0
3 5 2 3 4 0
4 4 3 4 4 2
5 6 0 5 4 1
6 3 3 6 2 2
COVERAGE OF BONE ON IMPLANT SURFACES
I
II
III
IV
52%
26%
62%
63%
63%
Micrograph - IV
I
II
III
IV
Micrograph - III
89%
83%
94%
63%
81%

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coverage was significantly greater for Si-HA when compared to hydroxyapatite (HA) (Patel N, et al. J Mater Sci Mater Med
2002;13:1199 –1206)”. “It is suggested that an increase in the density of triple junctions in Si-HA is the mechanism by which Si
increases the solubility of HA and the subsequent rate at which bone apposes to Si-HA ceramics (Alexandra E. Porter, Serena
M. Best, William Bonfield.).” Solution methodology is detailed as below:
Fig. (a) Details – Weibel Grid

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Fig. (b) Details – Merz Grid

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REFERENCES:
(a) Patel, N., Best, S.M. & Bonfield, W. 2002, "A comparative study on the in vivo behavior of hydroxyapatite and silicon
substituted hydroxyapatite granules", Journal of Materials Science: Materials in Medicine [H.W. Wilson - AST], vol. 13,
no. 12, pp. 1199.
(b) Porter, A.E., Buckland, T., Hing, K., Best, S.M. & Bonfield, W. 2006, "The structure of the bond between bone and porous
silicon-substituted hydroxyapatite bioceramic implants", Journal of biomedical materials research. Part A,vol. 78, no. 1,
pp. 25-33.