Surface bound bisphosphonate for implant fixation in bone

With improved implants, the high risk of implant failure for younger patients might be reduced. Further, indications for orthopaedic or odontologic procedures might be widened. The number of surgical procedures has been increased due to improved surgical techniques and implants. If the complications decrease further, it will be possible to treat even less severe cases with surgical procedures.

During the surgical preparation of bone, prior to insertion of an implant, bone will be traumatized which leads to local resorption. Consequently, early implant fixation might be reduced. Impaired early fixation, as evidenced by radiostereometry, has been associated with increased risk of late loosening. Bisphosphonates are known to inhibit bone resorption by osteoclasts and have shown to increase implant fixation when administered systemically or locally directly at the bone prior to implant insertion.A method to bind bisphosphonates directly to the implant was developed. Stainless steel screws were coated with crosslinked fibrinogen, serving as an anchor for bisphosphonate attachment. The screws were inserted in the tibial metaphysis in rats and implant fixation was analyzed with pullout measurements. Bisphosphonate coated screws turned out to have 28 % higher pullout force at 2 weeks compared to control screws with the fibrinogen coating only. The next experiment was designed to measure at what stage in the healing process the strongest bisphosphonate effect was gained. Bisphosphonate coated screws were expected to reduce the resorption of the traumatized bone. However, no decreased fixation was found in the control group. Instead, the fixation increased with time, and so did the effect of the bisphosphonates…


Implant fixation, clinical aspects
Why does fixation of implants in bone need to be improved?
Why do orthopaedic prostheses and dental fixtures come loose?
Implant fixation, biological aspects
What happens initially at the cellular level around the implant?
Implant screws in the cortex, in animals
Are there critical phases for fixation of implants in bone?
What constitutes the bone to implant interface?
What influence does micromotion have on endosseous implant fixation?
What is the bisphosphonate mechanism of action?
Do bisphosphonates influence other cells than osteoclasts?
Are bisphosphonates used in orthopaedics to improve implant fixation?
What is osteonecrosis of the jaw?
What has been done on bisphosphonate coated implants?
A novel coating technique
Screw coating
Measurements of coating thicknesses
Mechanical measurements
Pullout measurements
Removal torque measurements
Paper I. Surface-bound bisphosphonates enhance screw fixation in rats – increasing effect up to 8 weeks after insertion
Paper II. Bisphosphonate coating on titanium screws increases the
mechanical fixation in rat tibia after 2 weeks
Paper III. Stainless steel screws coated with bisphosphonates gave stronger
fixation and more surrounding bone. Histomorphometry in rats
Paper IV. A bisphosphonate coating improves the bony fixation of stainless
steel screws in ovariectomized rats
Pharmacological improvement of implant fixation
Effects of the fibrinogen layer
Stainless steel and titanium
Estrogen and implant fixation
Micromotion and hydroxyapatite
Osteonecrosis of the jaw
Future experiments

Author: Wermelin, Karin

Source: Linköping University

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