Wasielewski R C, Galante J O, Leighty R M, Natarajan R N, Rosenberg A G
Department of Orthopaedic Surgery, Ohio State University Hospital, Columbus 43210.
Clin Orthop Relat Res. 1994 Feb(299):31-43.
Fifty-five unconstrained polyethylene tibial inserts were retrieved at revision total knee arthroplasty and examined for evidence of wear after a mean implantation time of 34.2 months (2.5-80 months). Twenty inserts were ultra-high molecular weight polyethylene (UHMWPE) and 35 were carbon-reinforced polyethylene. Topographic maps of the articular and metal-backed surfaces of each component were constructed to characterize the extent and location of polyethylene degradation, identified visually by mode. In 32 of the retrieved inserts, pre- and postarthroplasty or prerevision radiographs were analyzed for component positioning, sizing, and extremity alignment. These factors then were compared with the patterns and severity of polyethylene wear on the inserts to establish correlations. Severe generalized articular wear was seen in inserts with third body wear from patellar metal-backed failure and cement debris. Severe localized delamination wear was seen in inserts with rotational-subluxation patterns of wear (p = 0.05). The external rotation subluxation wear pattern was strongly associated with knees that had lateral subluxation of the patella (p = 0.0002). Articular wear and cold flow into screw holes tended to be greater in the tightest prearthroplasty compartment (medial in the varus knee [p = 0.0157]; lateral in the valgus knees [p = 0.0226]). Fourteen of 16 knees with a preoperative varus deformities--even when corrected to a normal postarthroplasty anatomic axis--still had greater medial compartment articular wear (p = 0.001). Twelve of these knees did not have a medial release at the time of initial arthroplasty. Preoperative varus also was found to be related to the occurrence of posteromedial cold flow of polyethylene into tibial tray screw holes (p = 0.007). Increasing tibial insert posterior slope was associated with increasingly posterior articular wear track location (p = 0.03). This study indicates that unconstrained tibial component wear patterns and severity may be associated with clinical and mechanical factors under the surgeon's control, including component size and position, and knee alignment and ligament balance.
在翻修全膝关节置换术中取出55个非限制性聚乙烯胫骨衬垫，在平均植入时间34.2个月（2.5 - 80个月）后检查磨损迹象。20个衬垫为超高分子量聚乙烯（UHMWPE），35个为碳增强聚乙烯。构建每个部件的关节面和金属背面的地形图，以表征聚乙烯降解的程度和位置，通过模式直观识别。在32个取出的衬垫中，分析了置换术前和术后或翻修术前的X线片，以确定部件的位置、尺寸和肢体对线情况。然后将这些因素与衬垫上聚乙烯磨损的模式和严重程度进行比较，以建立相关性。在因髌骨金属背衬失效和骨水泥碎片导致三体磨损的衬垫中，可见严重的广泛性关节磨损。在具有旋转半脱位磨损模式的衬垫中，可见严重的局部分层磨损（p = 0.05）。外旋半脱位磨损模式与髌骨外侧半脱位的膝关节密切相关（p = 0.0002）。在置换术前最紧的间隙中（内翻膝为内侧间隙 [p = 0.015７]；外翻膝为外侧间隙 [p = 0.0226]）关节磨损和向螺钉孔内的冷流往往更严重。16个术前有内翻畸形的膝关节中，有14个——即使在置换术后矫正至正常解剖轴线——内侧间隙的关节磨损仍更严重（p = 0.001）。其中12个膝关节在初次置换时未进行内侧松解。术前内翻还被发现与聚乙烯向胫骨托螺钉孔的后内侧冷流的发生有关（p = 0.007）。胫骨衬垫后倾增加与关节磨损轨迹位置越来越靠后有关（p = 0.03）。本研究表明，非限制性胫骨部件的磨损模式和严重程度可能与外科医生可控制的临床和机械因素有关，包括部件尺寸和位置、膝关节对线和韧带平衡。
