Teeter Matthew G, Howard James L, McCalden Richard W, Naudie Douglas D
Division of Orthopaedic Surgery, Schulich School of Medicine & Dentistry, Western University and London Health Sciences Centre, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada; Surgical Innovation Program, Lawson Health Research Institute, London, ON, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada.
Division of Orthopaedic Surgery, Schulich School of Medicine & Dentistry, Western University and London Health Sciences Centre, London, ON, Canada.
Knee. 2017 Mar;24(2):429-433. doi: 10.1016/j.knee.2016.12.010. Epub 2017 Feb 8.
Unicompartmental knee replacement (UKR) is an alternative to total knee replacement for selected patients with isolated medial or lateral compartment osteoarthritis. One of the most popular UKR implants was introduced as a mobile-bearing design in part to reduce polyethylene wear. However, backside wear of the mobile-bearing implant has not been examined independently from the articular surface.
Sixteen retrieved polyethylene inserts from a medial mobile-bearing UKR from 16 patients were examined after an average of 4.2years implantation (range 1.5 to 10.0years). Reasons for revision included aseptic loosening, pain, and progression of osteoarthritis. Each retrieved insert was evaluated using visual damage scoring across the articular and backside surfaces. Inserts were also micro-CT scanned and compared to a reference insert of the same size, to measure wear on the articular and backside surfaces.
The total damage scores were greater (p=0.01) on the articular surface (27.2±5.7 (standard deviation)) than the backside surface (23.8±6.2). Burnishing, abrasions, and pitting were the most common damage modes on both surfaces, with only pitting greater (p=0.03) on the articular surface than the backside surface. There was no difference (p=0.46) in wear rate between the articular surface (0.028±0.025mm/year) and backside surface (0.029±0.017mm/year).
The retrieved mobile-bearing UKR polyethylenes demonstrated good overall wear resistance, with no evidence of severe damage. However, backside wear was equal to articular wear, suggesting that the backside surface is a potential source of polyethylene wear debris.
单髁膝关节置换术（UKR）是针对特定的孤立性内侧或外侧间室骨关节炎患者的全膝关节置换术的替代方案。最受欢迎的UKR植入物之一采用了活动平台设计，部分原因是为了减少聚乙烯磨损。然而，活动平台植入物的背面磨损尚未与关节表面分开进行研究。
对16例患者的内侧活动平台UKR中取出的16个聚乙烯衬垫进行检查，平均植入时间为4.2年（范围1.5至10.0年）。翻修原因包括无菌性松动、疼痛和骨关节炎进展。对每个取出的衬垫在关节面和背面进行视觉损伤评分评估。衬垫还进行了显微CT扫描，并与相同尺寸的参考衬垫进行比较，以测量关节面和背面的磨损情况。
关节面的总损伤评分（27.2±5.7（标准差））高于背面（23.8±6.2）（p=0.01）。打磨、擦伤和点蚀是两个表面最常见的损伤模式，只有关节面的点蚀比背面更严重（p=0.03）。关节面（0.028±0.025mm/年）和背面（0.029±0.017mm/年）的磨损率无差异（p=0.46）。
取出的活动平台UKR聚乙烯材料显示出良好的整体耐磨性，没有严重损伤的迹象。然而，背面磨损与关节面磨损相当，表明背面是聚乙烯磨损碎屑的潜在来源。
