title: Surface polishing positively influences ease of plate and screw removal.
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 parallel but not electropolished TAN screws (p=0.066). Ex vivo, soft tissue removal was much easier (approximately 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.
authors.affiliation: AO Research Institute Davos, AO Foundation, Clavadelerstrasse, 8, CH-7270, Davos Platz, Switzerland.
authors.forename: J S
authors.initials: JS
authors.lastname: Hayes
authors.forename: U
authors.initials: U
authors.lastname: Seidenglanz
authors.forename: A I
authors.initials: AI
authors.lastname: Pearce
authors.forename: S G
authors.initials: SG
authors.lastname: Pearce
authors.forename: C W
authors.initials: CW
authors.lastname: Archer
authors.forename: R G
authors.initials: RG
authors.lastname: Richards
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001860:Bone Plates / Q000009:adverse effects / Q000592:standards*; D001863:Bone Screws / Q000009:adverse effects / Q000592:standards*; D001842:Bone and Bones / Q000502:physiology / Q000601:surgery; D020878:Device Removal / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005549:Foreign-Body Reaction / Q000503:physiopathology / Q000517:prevention & control*; D005592:Fracture Fixation / Q000009:adverse effects / Q000379:methods*; D007219:Industrial Oils; D008422:Materials Testing / Q000379:methods; D010012:Osteogenesis / Q000502:physiology; D011474:Prosthesis Design / Q000379:methods*; D017755:Prosthesis Fitting / Q000379:methods; D012086:Reoperation; D034561:Sheep, Domestic; D014025:Titanium / Q000009:adverse effects / Q000592:standards
chemical_list: D001672:Biocompatible Materials; D014025:Titanium