Hydroxyapatite coating of threaded pins enhances fixation

Area of Science:

• Orthopedics
• Biomaterials Science
• Medical Device Engineering

Background:

• Osteoarthritis of the knee is a degenerative joint disease often requiring surgical intervention.
• External fixation is a common orthopedic technique for stabilizing fractures and bone segments.
• Hydroxyapatite (HA) coating is a biomaterial used to enhance bone integration and implant stability.

Purpose of the Study:

• To compare the insertion and extraction torque forces of standard tapered screws versus hydroxyapatite (HA)-coated screws in patients undergoing hemicallotasis for medial knee osteoarthritis.
• To evaluate the effect of HA coating on screw fixation stability in the proximal tibial metaphysis and diaphysis.

Main Methods:

• A randomized study involving 19 patients with medial knee osteoarthritis treated with hemicallotasis.
• 76 external fixation screws were used: standard tapered screws and HA-coated screws.
• Insertion and extraction torque forces were measured for screws placed in the proximal tibial metaphysis and diaphysis.

Main Results:

• No significant difference in insertion torque forces between standard and HA-coated screws.
• Extraction torque forces were significantly higher for HA-coated screws in the diaphysis (p < 0.005).
• Significantly fewer HA-coated screws loosened in the metaphysis (1/18) compared to standard screws (18/18).
• Standard screws in the diaphysis lost approximately 40% of fixation, while HA-coated screws retained full fixation.

Conclusions:

• Hydroxyapatite coating significantly enhances the long-term fixation stability of external fixation screws in the tibial diaphysis.
• HA coating reduces screw loosening in the tibial metaphysis, improving overall implant stability in knee osteoarthritis treatment.
• HA-coated screws represent a promising advancement for improving outcomes in external fixation procedures.