Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Caspar Theyß Strasse 27-31, Grunewald, 14193, Berlin, Germany,
Arch Orthop Trauma Surg. 2014 Aug;134(8):1147-53. doi: 10.1007/s00402-014-2013-9. Epub 2014 Jun 5.
Interference screw fixation is a standard procedure in anterior cruciate ligament (ACL) replacement. Aim of this study was to evaluate the degradation process of Poly-D-L-lactide (PDLLA) interference screws used for tibial ACL graft fixation.
We evaluated magnetic resonance imaging (MRI) scans of 18 patients who underwent ACL revision surgery at different time points after anatomic ACL reconstruction. At primary surgery, a tibial hybrid fixation was performed with a degradable interference (IF) screw made of PDLLA (Megafix(®)) and a button.
MRI revealed three different phases of degradation of the PDLLA screw. 6-8 months after surgery the IF screw was clearly visible as a well-defined structure on MRI and CT scan. After 12-16 months, the screws appeared less defined with central ingrowths' of connective tissue. In some cases only fragmented screw material was visible. At these time points, there was a slight edema surrounding the tunnel visible on MRI. After 22 months and later, the mean screw site densities were comparable with the surrounding bone density. There was no edema or signs of inflammation around the bone tunnels visible. Presence of cystic or osteolytic changes was not detected.
After 22 months, a PDLLA screw may not interfere with ACL revision surgery. Regarding the degradation process of PDLLA screws, we noted three different phases. Furthermore, the degradation process observed by MRI resembles to that described by animal studies. The PDLLA screws fully absorb and are partially replaced by bone. The degradation process in humans seems to be longer than that described in animals.
在前交叉韧带（ACL）重建中，干扰螺钉固定是一种标准程序。本研究旨在评估用于胫骨 ACL 移植物固定的聚-D-乳酸（PDLLA）干扰螺钉的降解过程。
我们评估了 18 例接受 ACL 翻修手术的患者的磁共振成像（MRI）扫描结果，这些患者在解剖学 ACL 重建后不同时间点进行了检查。在初次手术中，使用 PDLLA（Megafix®）制成的可降解干扰（IF）螺钉和纽扣进行胫骨混合固定。
MRI 显示 PDLLA 螺钉的降解过程分为三个不同阶段。术后 6-8 个月，IF 螺钉在 MRI 和 CT 扫描中清晰可见，呈明确结构。12-16 个月后，螺钉的定义变得不那么明确，出现了结缔组织的中心内生长。在某些情况下，仅可见碎片状的螺钉材料。在这些时间点，MRI 上可见隧道周围有轻微的水肿。22 个月及以后，平均螺钉部位密度与周围骨密度相当。在骨隧道周围没有水肿或炎症迹象。未发现囊性或溶骨性改变。
22 个月后，PDLLA 螺钉可能不会干扰 ACL 翻修手术。关于 PDLLA 螺钉的降解过程，我们观察到了三个不同的阶段。此外，MRI 观察到的降解过程与动物研究中描述的过程相似。PDLLA 螺钉完全吸收并部分被骨取代。人类的降解过程似乎比动物研究中描述的时间更长。
