Date of Award


Document Type


Degree Name

Master of Science (MS)



Committee Member

Dr. John DesJardins, PhD, Committee Chair

Committee Member

Dr. Marian Kennedy, PhD

Committee Member

Dr. Jeremy Tzeng, PhD


Infections have been reported to occur in up to 91% of patients after orthopaedic procedures. Many of these infections are caused by bacterial biofilm growth on the surface of the implanted device. Surface modifications of fracture fixation implants have been taken into consideration in order to reduce infection rates and improve clinical results in orthopaedic procedures. Effective surface treatments will also reduce the need for antibiotics and prevent formation of drug-resistant bacteria. Titanium alloy sample discs (N=144) were prepared with six surface roughness treatments through polishing as well as with four different concentrations of chitosan through spin coating. In vitro testing with Staphylococcus aureus bacteria (ATCC 25923) then determined the degree of biofilm resistance for the treated samples. Resulting trends indicate that surfaces with low to intermediate average roughness values (between 0.1-1.5 m) best prevent biofilm adhesion. Also, higher concentration of chitosan on these surfaces significantly reduce the amount of biofilm recovered from the surface. Biofilm concentration was seen to be significantly affected by surface roughness [F(5, 120) = 36.45, p = 1.45E-22] as well as chitosan concentration [F(3, 120) = 3.85, p = 0.0114]. The interaction between these two independent variables was also significant [F(15, 120) = 7.88, p = 4.56E-12]. This supplements the results of previous research studies and confirms that Staphylococcus aureus biofilms can be manipulated through surface treatment variations. These findings open doors for the medical industry through an increased awareness of the valuable use of physical and chemical surface modifications on orthopaedic implant devices.



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