Intraoperative assessment of midflexion laxity in total knee prosthesis

• Published in: The knee Vol. 21; no. 4; pp. 810 - 814
• Main Authors: Minoda, Yukihide, Nakagawa, Shigeru, Sugama, Ryo, Ikawa, Tessyu, Noguchi, Takahiro, Hirakawa, Masashi, Nakamura, Hiroaki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2014; Elsevier Limited
• Subjects: Aged; Aged, 80 and over; Arthritis; Biomechanical Phenomena; Design; Female; Humans; Intra-operative joint kinematics; Intraoperative Period; Joint Instability - pathology; Joint surgery; Knee; Knee Joint - pathology; Knee Joint - physiopathology; Knee Prosthesis; Male; Middle Aged; Midflexion instability; Orthopedics; Patient satisfaction; Polyethylene; Prostheses; Prosthesis Design; Range of Motion, Articular - physiology; Recovery of Function; Sports injuries; Studies; Tensor device; Total knee arthroplasty; Total knee arthroplasty; Intra-operative joint kinematics; Midflexion instability; Tensor device
• DOI: 10.1016/j.knee.2014.04.010
• ISSN: 0968-0160

Abstract Background Soft-tissue balancing of the knee is fundamental to the success of a total knee arthroplasty (TKA). In posterior-stabilized TKA, there is no stabilizer of the anterior–posterior translation in the midflexion range in which the cam-post mechanism does not engage yet. Therefore, instability in the midflexion range is suspected to occur in posterior-stabilized TKA. The purpose of this study was to measure the joint gap throughout a full range of motion and to analyze the joint gap laxity in the midflexion range after implantation of a mobile-bearing posterior-stabilized total knee prosthesis. Methods Joint gap kinematics in 259 knees with varus osteoarthritis were measured during TKAs using a tensor device with the same shape of a total knee prosthesis of the same design was used. After the implantation of a mobile-bearing posterior-stabilized prosthesis and the reduction of the patellofemoral joint, the joint gap was measured at 0°, 30°, 60°, 90°, 120°, and 145° of flexion. Results The center size of the joint gap was tight in extension and deep flexion and loose at midflexion ranges, especially at 30° of flexion ( p < 0.001). The symmetry of the joint gap was varus at 0° and 145° of flexion ( p < 0.001). Conclusions Our results showed the joint gap laxity in the midflexion range after the implantation of a mobile-bearing posterior-stabilized prosthesis. Our new tensor device, which can attach the polyethylene insert trial, will provide the important information about the joint gap kinematics after implantation of total knee prostheses. Level of evidence IV.