Vol.:(0123456789) 1 3 Knee Surgery, Sports Traumatology, Arthroscopy https://doi.org/10.1007/s00167-020-06209-9 KNEE Partial meniscectomy does not afect the biomechanics of anterior cruciate ligament reconstructed knee with a lateral posterior meniscal root tear Xin Tang 1,2  · Brandon Marshall 3  · Joon Ho Wang 2  · Junjun Zhu 3  · Jian Li 1  · Monica A. Linde 2  · Patrick Smolinski 2,3  · Freddie H. Fu 2,3 Received: 28 May 2020 / Accepted: 3 August 2020 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2020 Abstract Purpose The purpose of this study was to determine the efects of a lateral meniscus posterior root tear, partial meniscectomy, and total meniscectomy on knee biomechanics in the setting of anterior cruciate ligament (ACL) reconstruction. Methods Thirteen fresh-frozen cadaver knees were tested with a robotic testing system under an 89.0-N anterior tibial load at full extension (FE), 15°, 30°, 60° and 90° of knee fexion and a simulated pivot-shift loading (7.0 Nm valgus and 5.0 Nm internal tibial rotation) at FE, 15° and 30° of knee fexion. Anterior tibial translation (ATT) and the in-situ force of ACL graft under the diferent loadings were measured in four knee states: (1) ACL reconstruction with intact lateral meniscus (Intact meniscus), (2) ACL reconstruction with lateral meniscal posterior root tear (Root tear), (3) ACL reconstruction with lateral posterior partial meniscectomy (Partial meniscectomy) and (4) ACL reconstruction with total lateral meniscectomy (Total meniscectomy). Results Under anterior tibial loading, compared with an intact meniscus, root tear signifcantly increased ATT at 15° and 30° of knee fexion (p < 0.05) and partial meniscectomy had almost same increased ATT as with root tear at any knee fexion between FE and 90°. Under simulated pivot-shift loading, total meniscectomy increased ATT compared with intact meniscus, root tear, partial meniscectomy at FE (p < 0.05). Conclusion Under anterior tibial and simulated pivot-shift loading, partial meniscectomy has no signifcant efect on the stability of ACL-reconstructed knee with lateral meniscal posterior root tear, while total meniscectomy increased laxity at less than 30° of knee fexion. Clinically, in cases of irreparable meniscal root tears or persistent pain a partial meniscectomy can be considered in the setting of ACL reconstruction. Keywords Anterior tibial translation (ATT) · Pivot shift · Anterior cruciate ligament (ACL) · Meniscectomy Introduction The menisci have been recognized as the secondary restraint to anterior–posterior translation and rotational movement in the knee [21, 26, 38]. Injuries to the posterior medial meniscus root attachments have been shown to be related to clinically signifcant meniscal extrusion [20], which patently afects meniscal biomechanics, fnally resulting in degen- erative changes within the knee joint [4, 14, 16, 30]. Clini- cally, meniscal injuries are common and frequently involved in ACL injury [3, 5, 13]. Several studies recently have reported that posterior lateral meniscus root tears occurred in 6.6–14% of patients with ACL tear [6–8, 24, 34]. Regarding posterior lateral meniscus root tear, the best treatment currently remains controversy [28]. The treatment * Freddie H. Fu fu@upmc.edu 1 Department of Orthopaedic Surgery, West China Hospital, Sichuan University, Chengdu, China 2 Department of Orthopaedic Surgery, University of Pittsburgh, 3471 Fifth Avenue, Suite 1011, Pittsburgh, PA 15213, USA 3 Department of Mechanical Engineering and Material Science Engineering, University of Pittsburgh, Pittsburgh, PA, USA