Reports demonstrate up to 20% of total knee arthroplasty (TKA) patients are not satisfied and claim their knee does not feel normal. Failure to replicate native anterior cruciate ligament (ACL)-intact knee tibiofemoral kinematics and stability may contribute to this dissatisfaction. Originally described as medial-pivot pattern throughout flexion, recent studies have elucidated the more modern understanding of a complex motion pattern in ACL-intact knees, where walking and early flexion activities near extension exhibit a lateral-pivot pattern and medial-pivot pattern is observed in deeper flexion. A contemporary TKA design (EMPOWR 3-D; DJO Global, Vista, CA) has the potential to promote natural motion and stability by incorporating a conforming spherical lateral compartment to recreate the dual-pivot kinematics. In vivo fluoroscopic studies have confirmed this optimal kinematic pattern of medial-pivot motion during squatting and kneeling activities, with a lateral-pivot motion during walking. Further, near normal knee strength and minimized hamstrings co-contraction provide evidence for optimal intrinsic tibiofemoral stability. Emerging clinical results have been encouraging and support the modern dual-pivot kinematic understanding and in vivo function studies. Recent studies have revealed intraoperative dual-pivot femoral contact patterns optimize patient outcomes. Clinical results comparing the dual-pivot TKA and a traditional TKA design demonstrate patients with the dual-pivot TKA experience a higher level of function and a greater likelihood of a normal feeling knee. Merging the modern understanding of kinematics in ACL-intact knees with a contemporary dual-pivot TKA design may improve outcomes through optimal knee motion and stability, which may narrow the elusive 20% of TKA patients currently not satisfied.
*Department of Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL
†IU Health Saxony Hospital, Indiana University School of Medicine, Indianapolis, IN
S.A.B. and R.M.M. receive royalties and consulting fees from DJO Surgical.
For reprint requests, or additional information and guidance on the techniques described in the article, please contact Robert M. Meneghini, MD, at or by mail at Department of Orthopaedic Surgery, Indiana University Health Physicians Orthopedics and Sports Medicine, Indiana University School of Medicine, 13100 East 136th Street, Suite 2000, Fishers, IN 46037. You may inquire whether the author(s) will agree to phone conferences and/or visits regarding these techniques.