Objective To determine the relationship between preoperative static knee joint laxity and non-invasive quantitative pivot shift (QPS) in patients with anterior cruciate ligament (ACL) rupture.
Methods Patients with an ACL injury participating in a multicentre trial were analysed if they had complete preoperative data on the following laxity tests: the rolimeter, the KT-1000 (134 N and manual maximum force), the Lachman, the anterior drawer and QPS. The QPS was assessed via a non-invasive inertial sensor system and an image analysis system for tibial acceleration and lateral tibial translation, respectively. Awake examination and examination under anaesthesia (EUA) were performed. Correlation between absolute values of static laxity and the QPS for each leg was assessed by Spearman’s rho. The Lachman and the anterior drawer were dichotomised into low- and high-grade, and differences between the groups in terms of continuous values of QPS were assessed.
Results A total of 58 patients were included (41.4% women, mean age 27.1±9.8 years). Awake static laxity and QPS acceleration were negatively correlated in the ACL-deficient knee, meaning that a greater acceleration correlated to a lesser static tibial translation, and vice versa. The mean QPS acceleration correlated with the static tests as follows: the rolimeter r=−0.30 (P=0.024), the KT-1000 134 N r=−0.25 (P=0.06) and the KT-1000 manual maximum r=−0.37 (P=0.004). A negative correlation between awake QPS acceleration and the static tests was also shown for the non-involved knee. Patients with a high-grade Lachman’s test in the EUA had significantly greater QPS acceleration (P=0.0002) and QPS translation (P<0.001) compared with patients with a low-grade. The corresponding analysis for the anterior drawer showed a significantly greater QPS translation in the high-grade group (P=0.01), while no differences were found in the QPS acceleration.
Conclusion Static anteroposterior and dynamic knee laxities, as presented by QPS, are poorly correlated in the ACL-deficient knee and should therefore be considered as separate entities of the knee examination. These findings strengthen the implementation of non-invasive technology for quantification of the pivot shift when establishing treatment algorithms for ACL reconstruction.
Level of evidence Level III, prospective cohort.
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Contributors ES and EHS have substantially contributed to the acquisition of data, analysis of data and are responsible for drafting the work and revising it critically for important intellectual content. JM, VM and KS have substantially contributed to the acquisition of data, analysis of data and critically revising the work for important intellectual content. RK, SZ and JK have done large contributions to revise and design the manuscript. All authors have given their final approval of the manuscript to be published. In addition, all authors are in agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding The study was funded through a grant from the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) and the Orthopaedic Research and Education Foundation (OREF) (research grant no. 708661).
Competing interests RK reports personal fees from Medacta International, personal fees from Arthrex Inc., personal fees from B. Braun Aesculap Japan, personal fees from Zimmer Biomet, personal fees from Arthrex Japan GK, personal fees from Smith & Nephew KK, personal fees from Johnson & Johnson KK, grants from Stryker Japan KK, grants from Zimmer Biomet, grants from Smith & Nephew Orthopedics KK, grants from Astellas Pharm Inc., grants from Chugai Pharmaceutical Co., Ltd, grants from Taisyo Toyama Pharmaceutical Co., Ltd, grants from Pfizer Japan Inc., outside the submitted work. VM reports other (consulting) from Smith & Nephew, outside the submitted work.
Provenance and peer review Not commissioned; externally peer reviewed.
Collaborators The Pivot Study Group: James J Irrgang, Freddie H Fu, Adam Popchak, Paulo Araujo, Darren De SA, Neel Patel, Jayson Lian (Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA); Yuichi Hoshino, Masahiro Kurosaka, Kouki Nagamune (Kobe University, Kobe, Japan); Giulio Maria Marcheggiani Muccioli, Cecilia Signorelli, Nicola Lopomo, Alberto Grassi, Federico Raggi (Istituto Ortopedico Rizzoli, Bologna, Italy); David Sundemo (Sahlgrenska University Hospital, Gothenburg, Sweden).
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