title: Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability.
abstract: Little information is available to surgeons regarding how the lateral structures prevent instability in the replaced knee. The aim of this study was to quantify the lateral soft-tissue contributions to stability following cruciate-retaining total knee arthroplasty (CR TKA). Nine cadaveric knees were tested in a robotic system at full extension, 30°, 60°, and 90° flexion angles. In both native and CR implanted states, ±90 N anterior-posterior force, ±8 Nm varus-valgus, and ±5 Nm internal-external torque were applied. The anterolateral structures (ALS, including the iliotibial band), the lateral collateral ligament (LCL), the popliteus tendon complex (Pop T), and the posterior cruciate ligament (PCL) were transected and their relative contributions to stabilizing the applied loads were quantified. The LCL was found to be the primary restraint to varus laxity (an average 56% across all flexion angles), and was significant in internal-external rotational stability (28% and 26%, respectively) and anterior drawer (16%). The ALS restrained 25% of internal rotation, while the PCL was significant in posterior drawer only at 60° and 90° flexion. The Pop T was not found to be significant in any tests. Therefore, the LCL was confirmed as the major lateral structure in CR TKA stability throughout the arc of flexion and deficiency could present a complex rotational laxity that cannot be overcome by the other passive lateral structures or the PCL. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1902-1909, 2017.
authors.affiliation: Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Kiron K
authors.initials: KK
authors.lastname: Athwal
authors.affiliation: Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Hadi
authors.initials: H
authors.lastname: El Daou
authors.affiliation: Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Breck
authors.initials: B
authors.lastname: Lord
authors.affiliation: Guy's Hospital, Great Maze Pond, London SE1 9RT, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Davies
authors.affiliation: Department of Orthopaedic Surgery, Newcastle Freeman University Hospital, Newcastle, upon Tyne, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Manning
authors.affiliation: Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Rodriguez Y Baena
authors.affiliation: Department of Orthopaedic Surgery, Newcastle Freeman University Hospital, Newcastle, upon Tyne, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Deehan
authors.affiliation: Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.|Musculoskeletal Surgery Group, Department of Surgery and Cancer, Imperial College London School of Medicine, Charing Cross Hospital, London W6 8RF, United Kingdom.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Amis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007593:Joint Instability; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012399:Rotation
keywords: biomechanics; lateral collateral ligament; stability; total knee arthroplasty