Review on Evolution of Silicon Nitride in the
Field of Orthopedics
Sachin Ghalme* and Yogesh Falak
Department of Mechanical Engineering, Sandip Institute of Technology and Research Centre, India
Submission: January 19, 2018; Published: February 02, 2018
*Corresponding author: Sachin Ghalme, Department of Mechanical Engineering, Sandip Institute of Technology and Research Centre, Nashik (MS), India, Tel: +919890464305; Email: firstname.lastname@example.org
How to cite this article: Sachin G, Yogesh F. Review on Evolution of Silicon Nitride in the Field of Orthopedics. Curr Trends Biomedical Eng & Biosci.
2018; 11(5): 555824. DOI: 10.19080/
Knee and hip replacements offer great relief to number of patients around the world. Silicon Nitride (Si3N4) is a no-oxide ceramic material initially developed for industrial applications operating at extreme conditions and demanding high strength along with fracture resistance. Recently silicon nitride is applied in the field of orthopedic for replacement of hip and knee. This review covers the information and generation of silicon nitride for joint replacement in the field of orthopedic, which will be useful for engineering and biomedical professionals.
Silicon nitride is a non-oxide ceramic. It is an inorganic and non-metallic compound, made of silicon and nitrogen, vital elements for life [1-3]. It was discovered firstly 1857, but first synthetic silicon nitride was developed by Deville and Wohler in 1859 and came into picture when its commercial application began in 1950’s . Silicon nitride is a strong, having low thermal expansion, high temperature stability, high wear resistance
material to abrasion, corrosion and inert to most chemicals. It
has highest fracture resistance than any other ceramic materials. All these properties made it suitable for various industrial applications suitable for extreme operating conditions also. In 1994 Poper  published a paper on the application of Si3N4 ceramics, which was based on computer-searching in the American chemical abstracts system from the years 1967-1992, carried out by the Gmelin Institute (Staffordshire, UK). Table 1 shows properties of silicon nitride.
In 1970’s Alumina (Al2O3) and zirconia (ZrO2) ceramic introduced in orthopedic for replacement of hip and knee instead of CoCr because of less wear than metal surface [7-9]. Silicon nitride is non-oxide ceramic and has shown properties compatible for orthopedic surgery, various literature have presented suitability of silicon nitride for hip/knee joint replacement. It is biocompatible along with having higher strength and toughness [10,11]. Silicon nitride has two principle modes of wear: mechanical and tribo-chemical.the mechanical mode of wear observes at high load, low speed and start-stop
conditions. While, the tribo-chemical wear occurs during
dissolution of silicon nitride in lubricating environment. In
tribo-chemical wear hydrated silicon oxide layer forms between
articulating surfaces and it occurs during low load, low speed,
and continue motion. Wear testing of silicon nitride in presence
of water based lubrication shown very low coefficient of
friction and low wear rate . The wear of silicon nitride in
water mainly occurs due to tribochemical dissolution without
release of any solid wear particles. Sliding wear of silicon
nitride against silicon nitride in presence of water releases
silica. Some of investigations have reported that released silica
degrades in Phosphate Buffered Saline (PBS) and that Si ions
can be incorporated into bone tissue [13,14]. Boshiitskaya et
al.  in their work presented that silicon nitride dissolve in
blood serum, gastric juice and a synthetic biochemical media
at pH 7.4., suggesting that silicon nitride is biocompatible
and biodegradable along with compatible wear rate. Johanna
Olofsson et al.  evaluated the wear performance of silicon
nitride against silicon nitride in presence of PBS and bovine
serum, test result showed comparative wear rate than other
wear pairs and formation of tribo-film on surface controlling
friction and wear.
Any material used in orthopedic application must be bio inert.
Silicon nitride along with its superior mechanical properties
it is biocompatible. Kue et al.  assessed biocompatibility if
silicon nitride in vitro model using human osteoblast- like MG-
63 cell lines. They concluded that silicon nitride is a non-toxic,
biocompatible ceramic for propagation of functional human cells
in vitro. Guedes et al.  used silicon nitride implant in rabbit
tibias for 8 week and found no adverse reaction, with bone in
growth into and around the implants.
Silicon nitride is extensively used in orthopedic bearings
since from decades, because of its low wear rate and low
coefficient of friction than cobalt-chrome metal bearing.
Compared to oxide ceramic used in orthopedic, silicon nitride
has unique property to be formulated into a porous substrate
as well as a hard glassy bearing surface. As a porous material,
it is capable of bone in growth. Total joint replacement, like
prosthetic hip and knee replacement requires material with
low wear rate and low frictional coefficients. Silicon nitride
sliding against itself, or metal, or polyethylene becomes ultrasmooth
due to tribochemical polishing, and friction becomes
very low at increasing sliding distance . Thus silicon nitride
is very favorable for hip/knee joint replacement, considering its
tribological properties when articulating against itself in water.
Silicon nitride is radiolucent, so that both the implant and the
underlying bone can be visualized on plain radiography, which is
not possible with metal implants.
Silicon nitride has favorable properties, presenting
its potential for use in the biomedical field expecting
biocompatibility, strength, and endurance. With rise in number
of joint replacement surgeries demand for material with
high strength increased, so that life expectancy of joint can
be improved. Silicon nitride with its mechanical properties
and biocompatibility will play major role in joint replacement