2010 Volume No 19 – pages 117-126
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Title: Surface polishing positively influences ease of plate and screw removal |
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Author: JS Hayes, U Seidenglanz, AI Pearce, SG Pearce, CW Archer, RG Richards |
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Address: AO Research Institute Davos, AO Foundation, Clavadelerstrasse, 8, CH-7270, Davos Platz, Switzerland |
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E-mail: geoff.richards at aofoundation.org |
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Key Words: Implant removal, in vivo, locking compression plate, screw removal, commercially pure titanium, titanium-6%aluminium-7%niobium. |
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Publication date: February 26th 2010 |
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Abstract: Difficulties removing temporary fracture fixation devices due to excessive bony on-growth results in extended surgical time leading to excessive blood loss, debris contamination and potentially refracture. Commercially available locking plates and screws are manufactured for clinics with a micro-rough surface, which contributes to the excessive bony on-growth reported. We have applied polishing technology to commercially pure titanium locking compression plates (LCP) and titanium-6%aluminium-7%niobium (TAN) plates and screws to assess if it can alleviate problems with strong bony overgrowth. Samples were implanted for 6, 12 and 18 months in a bilateral sheep tibia non fracture model and assessed for screw removal torque, percentage of bone contact and tissue-material response. Both electropolishing (p=0.001) and paste polishing (p=0.010) of TAN screws significantly reduced the mean torque required for removal compared to their micro-rough counterparts. This was accompanied by a trend for a lower percentage of bone contact for polished screws. This difference in bone contact was significant for paste polished TAN screws (p<0.001) but not electropolished TAN screws (p=0.066). Ex vivo, soft tissue removal was much easier (~five minutes) for polished constructs, which was difficult and at least four times longer for standard micro-rough constructs. We suggest that polishing of locked plate/screw systems will improve ease of removal and reduce implant related removal complications encountered due to excessive strong bony on-growth while maintaining biocompatibility and implant stability. Future studies aim to assess the potential of this technology in the next level of complication, a fracture model. |
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Article download: Pages
117-126 (PDF file) |
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