Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
Department of Rehabilitation Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
Am J Sports Med. 2018 Oct;46(12):2859-2864. doi: 10.1177/0363546518793854. Epub 2018 Sep 7.
The presence of pivot shift after anterior cruciate ligament (ACL) reconstruction is correlated with worse clinical outcomes. An orthopaedic navigation system is a useful tool for quantifying laxity in the ACL-deficient knee.
To investigate the relationship between preoperative knee laxity measured by a navigation system and postoperative pivot shift (PPS) after ACL reconstruction.
Case-control study; Level of evidence, 3.
One hundred patients who underwent primary ACL reconstruction (62 hamstring tendon grafts, 38 patellar tendon grafts) were grouped according to the presence or absence of pivot shift at the 2-year follow-up, and the groups were compared retrospectively. Before surgery, knee laxity was assessed with a navigation system to quantify posterior tibial reduction (PTR) during pivot-shift tests and anterior tibial translation (ATT) during Lachman tests. PTR and ATT cutoff values were determined by receiver operator characteristic (ROC) analysis.
Preoperative PTR and ATT were significantly larger for patients with PPS (PPS-positive group) than those without (PPS-negative group). In the ROC analysis, the PTR had an area under the curve of 0.871 (95% CI, 0.763-0.979; P < .0001) for predicting a PPS; this was larger than that obtained for the ATT, which had an area under the curve of 0.825 (95% CI, 0.705-0.946; P = .001). Because the ROC curve of the ATT had 2 peaks, the ATT alone was not a suitable predictor for PPS. Based on the ROC curve, the optimal PTR cutoff value was 7 mm, with 88.9% sensitivity and 71.4% specificity for PPS (adjusted odds ratio = 19.7; 95% CI, 2.1-187.9; P = .009). Setting the cutoff value as a combination of the PTR (≧7 mm) and ATT (≧12 mm) improved the specificity (88.9% sensitivity and 84.6% specificity; adjusted odds ratio = 149.8; 95% CI, 5.9-3822.7; P = .002) over that with the PTR alone.
ACL injuries in knees with a large PTR had a higher risk of PPS. When reconstructing the ACL in a knee with a high degree of laxity, surgeons may need to adopt strategies to prevent PPS.
前交叉韧带（ACL）重建后出现枢轴点移位与临床结果较差相关。矫形导航系统是定量测量 ACL 缺失膝关节松弛度的有用工具。
研究导航系统测量的术前膝关节松弛度与 ACL 重建后术后枢轴点移位（PPS）之间的关系。
病例对照研究；证据水平，3 级。
100 例患者接受了初次 ACL 重建（62 例腘绳肌腱移植物，38 例髌腱移植物），根据 2 年随访时是否存在 PPS 进行分组，并进行回顾性比较。在手术前，使用导航系统评估膝关节松弛度，以量化枢轴点移位试验中的胫骨后移（PTR）和 Lachman 试验中的胫骨前移（ATT）。通过接受者操作特征（ROC）分析确定 PTR 和 ATT 的截断值。
PPS 阳性组患者的术前 PTR 和 ATT 明显大于 PPS 阴性组患者。ROC 分析显示，PTR 预测 PPS 的曲线下面积为 0.871（95%CI，0.763-0.979；P<0.0001），大于 ATT 的曲线下面积 0.825（95%CI，0.705-0.946；P=0.001）。由于 ATT 的 ROC 曲线有 2 个峰值，因此 ATT 本身并不是 PPS 的合适预测指标。基于 ROC 曲线，最佳 PTR 截断值为 7mm，PPS 的敏感性为 88.9%，特异性为 71.4%（调整优势比=19.7；95%CI，2.1-187.9；P=0.009）。将 PTR（≧7mm）和 ATT（≧12mm）的截断值组合起来，可以提高特异性（88.9%的敏感性和 84.6%的特异性；调整优势比=149.8；95%CI，5.9-3822.7；P=0.002），优于仅使用 PTR。
PTR 较大的 ACL 损伤膝关节发生 PPS 的风险更高。在膝关节高度松弛的情况下重建 ACL 时，外科医生可能需要采取策略来预防 PPS。
