Plancher Kevin D, Alwine Jeffrey T, Chan Jimmy J, Petterson Stephanie C
Department of Orthopaedics, Albert Einstein College of Medicine, New York, New York, USA.
Department of Orthopaedic Surgery, Weill Cornell Medical College, New York, New York, USA.
Orthop J Sports Med. 2020 Sep 25;8(9):2325967120952674. doi: 10.1177/2325967120952674. eCollection 2020 Sep.
The accessory medial portal (AMP) used for anatomic anterior cruciate ligament reconstruction (ACLR) is gaining popularity. This portal is routinely created at 60° of knee flexion, placing the infrapatellar branch of the saphenous nerve (IBSN) and, less commonly, the descending and superior medial genicular arteries at risk.
PURPOSE/HYPOTHESIS: The purpose of this study was to identify a safe zone for AMP placement in ACLR to minimize the risk of injury to the IBSN. We hypothesized that increased knee flexion angles would decrease the risk to neurovascular structures when creating an AMP.
Descriptive laboratory study.
A total of 20 cadaveric (10 matched pairs) knees were used for dissection to identify the IBSN and other neurovascular structures. A 30° arthroscope was used to make the central medial portal and AMP at 3 knee flexion angles (60°, 90°, and 110°). Distances were measured from the AMP to branches of the IBSN. Safety of AMP placement was analyzed by assessing the frequency at which spinal needles pierced a neurovascular structure or violated a safe zone.
The superior IBSN was significantly closer to the AMP than inferior IBSN. The AMP was significantly farther from the superior IBSN at 110° (8.56 ± 5.28 mm) compared with 60° (5.63 ± 5.00 mm; = .015) and 90° (6.69 ± 5.03 mm; = .006). A triangular safe zone was identified at 110° of knee flexion. No neurovascular structures were pierced, and the IBSN was not present in the safe zone. At 90°, the IBSN was not pierced; however, the IBSN did violate the safe zone at 90° of knee flexion.
The superior IBSN is at risk for iatrogenic injury with an AMP placed at 60° of knee flexion. The nerve moved distally with knee flexion. While no neurovascular structures were compromised at 90° of knee flexion, the nerve was found to course through the safe zone. A safe zone at 110° of knee flexion decreases the risk of neurovascular injury and makes the AMP safe for ACLR.
The AMP at 60° of knee flexion for ACLR poses risk to the IBSN. The IBSN did violate the safe zone at 90° of flexion. We recommend creating an AMP with increased knee flexion to 110° to decrease the risk of iatrogenic injury. When establishing an AMP, one should aim for the center of the defined safe zone, given that the spinal needle used in this study has a smaller diameter than a stab incision.
用于解剖学前交叉韧带重建（ACLR）的辅助内侧入路（AMP）越来越受欢迎。该入路通常在膝关节屈曲60°时建立，使隐神经髌下支（IBSN）以及较少见的膝降动脉和膝上内侧动脉处于危险之中。
目的/假设：本研究的目的是确定ACLR中AMP放置的安全区域，以尽量减少IBSN损伤的风险。我们假设增加膝关节屈曲角度会降低建立AMP时对神经血管结构的风险。
描述性实验室研究。
共使用20具尸体（10对配对）膝关节进行解剖，以识别IBSN和其他神经血管结构。使用30°关节镜在3个膝关节屈曲角度（60°、90°和110°）制作中央内侧入路和AMP。测量从AMP到IBSN分支的距离。通过评估脊柱穿刺针穿刺神经血管结构或侵犯安全区域的频率来分析AMP放置的安全性。
IBSN上支比下支明显更靠近AMP。与60°（5.63±5.00mm；P = 0.015）和90°（6.69±5.03mm；P = 0.006）相比，110°时AMP与IBSN上支的距离明显更远（8.56±5.28mm）。在膝关节屈曲110°时确定了一个三角形安全区域。没有神经血管结构被穿刺，并且安全区域内不存在IBSN。在90°时，IBSN未被穿刺；然而，在膝关节屈曲90°时IBSN确实侵犯了安全区域。
在膝关节屈曲60°时放置AMP，IBSN上支有医源性损伤的风险。神经随着膝关节屈曲向远端移动。虽然在膝关节屈曲90°时没有神经血管结构受到损害，但发现神经穿过安全区域。膝关节屈曲110°时的安全区域可降低神经血管损伤的风险，并使AMP在ACLR中安全。
ACLR中膝关节屈曲60°时的AMP对IBSN构成风险。在屈曲90°时IBSN确实侵犯了安全区域。我们建议将膝关节屈曲增加到110°来建立AMP，以降低医源性损伤的风险。在建立AMP时，应瞄准定义安全区域的中心，因为本研究中使用的脊柱穿刺针直径小于刺切口。
