Lutz Patricia M, Achtnich Andrea, Schütte Vincent, Woertler Klaus, Imhoff Andreas B, Willinger Lukas
Department for Orthopedic Sports Medicine, Technical University Munich, Ismaninger Strasse 22, 81675, Munich, Germany.
Department for Orthopedic and Trauma Surgery, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Strasse 40, 06120, Halle (Saale), Germany.
Knee Surg Sports Traumatol Arthrosc. 2022 Oct;30(10):3258-3267. doi: 10.1007/s00167-021-06777-4. Epub 2021 Nov 5.
Magnetic resonance imaging (MRI) signal intensity is correlated to structural postoperative changes of the anterior cruciate ligament (ACL) autograft. The purpose of this study was to investigate the ACL autograft maturation process via MRI over 2 years postoperatively, compare it to a native ACL signal and correlate the results with clinical outcome, return to preinjury sports levels, and knee laxity measurements.
ACL autograft signal intensity was measured in 17 male patients (age, 28.3 ± 7.0 years) who underwent ACL reconstruction with hamstring autograft at 6 weeks, 3-, 6-, 12-, and 24 months postoperatively by 3 Tesla MRI. Controls with an intact ACL served as control group (22 males, 8 females; age, 26.7 ± 6.8 years). An ACL/PCL ratio (APR) and ACL/muscle ratio (AMR) was calculated to normalize signals to soft tissue signal. APR and AMR were compared across time and to native ACL signal. Clinical outcome scores (IKDC, Lysholm), return to preinjury sports levels (Tegner activity scale), and knee laxity measurement (KT-1000) were obtained and correlated to APR and AMR at the respective time points.
The APR and AMR of the ACL graft changed significantly from the lowest values at 6 weeks to reach the highest intensity after 6 months (p < 0.001). Then, the APR and AMR were significantly different from a native ACL 6 months after surgery (p < 0.01) but approached the APR and AMR of the native ACL at 1- and 2 years after surgery (p < 0.05). The APR changed significantly during the first 2 years postoperatively in the proximal (p < 0.001), mid-substance (p < 0.001), and distal (p < 0.01) intraarticular portion of the ACL autograft. A hypo-intense ACL MRI signal was associated with return to the preinjury sports level (p < 0.05). No correlation was found between ACL MRI graft signal and clinical outcome scores or KT-1000 measurements.
ACL grafts undergo a continuous maturation process in the first 2 years after surgery. The ACL graft signals became hyper-intense 6 months postoperatively and approximated the signal of a native intact ACL at 12- and 24 months. Patients with a hypo-intense ACL graft signal at 2 years follow-up were more likely to return to preinjury sports levels. The results of the present study provide a template for monitoring the normal ACL maturation process via MRI in case of prolonged clinical symptoms. However, subjective outcome and clinical examination of knee laxity remain important to assess the treatment success and to allow to return to sports.
III.
磁共振成像（MRI）信号强度与前交叉韧带（ACL）自体移植物术后的结构变化相关。本研究的目的是通过术后2年的MRI来研究ACL自体移植物的成熟过程，将其与天然ACL信号进行比较，并将结果与临床结果、恢复到伤前运动水平以及膝关节松弛度测量结果相关联。
对17例男性患者（年龄28.3±7.0岁）进行了研究，这些患者在术后6周、3个月、6个月、12个月和24个月时接受了3特斯拉MRI检查，他们均采用自体腘绳肌腱进行了ACL重建。ACL完整的对照组（22例男性，8例女性；年龄26.7±6.8岁）。计算ACL/后交叉韧带比值（APR）和ACL/肌肉比值（AMR），以便将信号标准化为软组织信号。对APR和AMR随时间变化情况以及与天然ACL信号进行比较。获取临床结果评分（IKDC、Lysholm）、恢复到伤前运动水平（Tegner活动量表）以及膝关节松弛度测量结果（KT-1000），并将其与相应时间点的APR和AMR相关联。
ACL移植物的APR和AMR从术后6周的最低值显著变化，在6个月后达到最高强度（p<0.001）。然后，术后6个月时APR和AMR与天然ACL有显著差异（p<0.01），但在术后1年和2年时接近天然ACL的APR和AMR（p<0.05）。术后头2年，ACL自体移植物关节内近端（p<0.001）、中间部分（p<0.001）和远端（p<0.01）的APR有显著变化。ACL MRI信号低强度与恢复到伤前运动水平相关（p<0.05）。未发现ACL MRI移植物信号与临床结果评分或KT-1000测量结果之间存在相关性。
ACL移植物在术后头2年经历持续的成熟过程。ACL移植物信号在术后6个月时变为高强度，并在12个月和24个月时接近天然完整ACL的信号。在2年随访时ACL移植物信号低强度的患者更有可能恢复到伤前运动水平。本研究结果为在临床症状持续存在的情况下通过MRI监测正常ACL成熟过程提供了一个模板。然而，主观结果和膝关节松弛度的临床检查对于评估治疗成功与否以及允许恢复运动仍然很重要。
III级。
