title: Peripheral snap-fit locking mechanisms and smooth surface finish of tibial trays reduce backside wear in fixed-bearing total knee arthroplasty.
abstract: Background and purpose - Severe backside wear, observed in older generations of total knee replacements (TKRs), led to redesign of locking mechanisms to reduce micromotions between tibial tray and inlay. Since little is known about whether this effectively reduces backside wear in modern designs, we examined backside damage in retrievals of various contemporary fixed-bearing TKRs. Patients and methods - A consecutive series of 102 inlays with a peripheral (Stryker Triathlon, Stryker Scorpio, DePuy PFC Sigma, Aesculap Search Evolution) or dovetail locking mechanism (Zimmer NexGen, Smith and Nephew Genesis II) was examined. Articular and backside surface damage was evaluated using the semiquantitative Hood scale. Inlays were examined using scanning electron microscopy (SEM) to determine backside wear mechanisms. Results - Mean Hood scores for articular (A) and backside (B) surfaces were similar in most implants-Triathlon (A: 46, B: 22), Genesis II (A: 55, B: 24), Scorpio (A: 57, B: 24), PFC (A: 52, B: 20); Search (A: 56, B: 24)-except the NexGen knee (A: 57, B: 60), which had statistically significantly higher backside wear scores. SEM studies showed backside damage caused by abrasion related to micromotion in designs with dovetail locking mechanisms, especially in the unpolished NexGen trays. In implants with peripheral liner locking mechanism, there were no signs of micromotion or abrasion. Instead, "tray transfer" of polyethylene and flattening of machining was observed. Interpretation - Although this retrieval study may not represent well-functioning TKRs, we found that a smooth surface finish and a peripheral locking mechanism reduce backside wear in vivo, but further studies are required to determine whether this actually leads to reduced osteolysis and lower failure rates.
authors: a Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery , Poznań University of Medical Sciences.
authors: Łukasz
authors: Ł
authors: Łapaj
authors: b Metal Forming Institute.
authors: Adrian
authors: A
authors: Mróz
authors: a Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery , Poznań University of Medical Sciences.
authors: Paweł
authors: P
authors: Kokoszka
authors: a Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery , Poznań University of Medical Sciences.
authors: Jacek
authors: J
authors: Markuszewski
authors: a Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery , Poznań University of Medical Sciences.
authors: Justyna
authors: J
authors: Wendland
authors: c Department of Bioinformatics and Computational Biology , Poznań University of Medical Sciences.|d Clinical Eye Unit and Pediatric Ophtalmology Service , Heliodor Swiecicki University Hospital, Poznań University of Medical Sciences , Poznań , Poland.
authors: Celina
authors: C
authors: Helak-Łapaj
authors: a Department of General Orthopaedics, Musculoskeletal Oncology and Trauma Surgery , Poznań University of Medical Sciences.
authors: Jacek
authors: J
authors: Kruczyński
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D020959:Polyethylene; D011379:Prognosis; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D013499:Surface Properties; D013977:Tibia / Q000601:surgery*
chemical_list: D020959:Polyethylene