Wahbeh Jenna M, Sangiorgio Sophia N, Park Sang-Hyun, Cornwall G Bryan, Kulkarni Neha V, Chiesa Roberto, Ebramzadeh Edward
The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, The Luskin Orthopaedic Institute for Children in Alliance with UCLA, Los Angeles, CA, United States.
Henry Samueli School of Engineering Department of Bioengineering, University of California, Los Angeles, CA, United States.
N Am Spine Soc J. 2025 Jul 5;23:100768. doi: 10.1016/j.xnsj.2025.100768. eCollection 2025 Sep.
The Porous Coated Motion (PCM) is a ball-and-socket cervical disc replacement with excellent reported short-term clinical outcome. However, longer-term studies identified migration as a common cause of implant removal and the device was withdrawn from the market. Given these discrepancies, retrieval analyses are crucial to assess whether preclinical testing accurately predicts clinical performance. This study aimed to quantitatively and qualitatively analyze retrieved PCM devices to identify primary reasons for removal and assess the impact of observed damage on overall device fixation.
Thirty-seven PCM devices were received for postmarket surveillance. Nondestructive analysis included visual examination, photographic documentation, and radiographic review. Analytical measurements were performed using a coordinate measuring machine to assess articulating surfaces or a digital microscope for endplate surface feature characterization. Oxidation analysis was performed on all devices with adequate handling and storage conditions, and histopathology was performed when tissue samples were available.
Twenty-five devices met the inclusion criteria for this study. The mean patient age at retrieval was 45.3±13.5 years, with an average time-in-vivo of 121±15.6 days. Anterior migration was the most common reason for removal, reported in 17 cases, with the inferior convex polyethylene component predominately migrating. Additionally, 17 devices had a focalized deviation on the posterior quadrant of the articulating polyethylene ball, 11 of which had evidence of radiographic clinical migration. Histopathology and metrology findings indicated that wear debris did not contribute to clinical failure.
The findings of the present study, specifically the minimal bony ongrowth, lack of extraction damage, and radiographic imaging, indicated that most devices were removed due to migration. Metrology analysis revealed a depression on the posterior edge of the inferior endplate polyethylene ball, which correlated with anterior slippage. This may be a distinctive feature of the PCM's relatively large ball-and-socket design that led to increased stress during extension, causing anterior migration.
多孔涂层活动型（PCM）是一种球窝式颈椎间盘置换物，据报道其短期临床效果良好。然而，长期研究发现移位是植入物取出的常见原因，该装置已退出市场。鉴于这些差异，取出物分析对于评估临床前测试是否能准确预测临床性能至关重要。本研究旨在对取出的PCM装置进行定量和定性分析，以确定取出的主要原因，并评估观察到的损伤对整体装置固定的影响。
接收了37个用于上市后监测的PCM装置。非破坏性分析包括目视检查、摄影记录和放射学检查。使用坐标测量机对关节表面进行分析测量，或使用数字显微镜对终板表面特征进行表征。对所有处理和储存条件合适的装置进行氧化分析，有组织样本时进行组织病理学检查。
25个装置符合本研究的纳入标准。取出时患者的平均年龄为45.3±13.5岁，体内平均时间为121±15.6天。向前移位是最常见的取出原因，17例报告为此原因取出，其中下凸聚乙烯部件移位占主导。此外，17个装置在关节聚乙烯球的后象限有局部偏差，其中11个有放射学临床移位的证据。组织病理学和计量学结果表明磨损碎屑不是临床失败的原因。
本研究的结果，特别是最小的骨长入、无取出损伤和放射影像学表现，表明大多数装置是因移位而取出。计量学分析显示下终板聚乙烯球后缘有凹陷，这与向前滑动相关。这可能是PCM相对较大的球窝设计的一个独特特征，导致伸展时应力增加，引起向前移位。
