title: In vivo kinematic evaluation of total hip arthroplasty during stair climbing.
abstract: Stair climbing is a physically demanding task and a painful limitation for patients suffering from severe hip osteoarthritis. Although total hip arthroplasty (THA) is the definitive treatment for end-stage osteoarthritis, it is not well understood whether THA restores hip kinematics during strenuous activities. The purpose of this study was to compare the 3D kinematics of THA and native hip during physically demanding tasks and correlate potential differences with THA components orientations/positions in patients with unilateral THA. In vivo hip kinematics were determined during step-up and leg stance activities using a validated combination of 3D CT-based computer modeling and dual fluoroscopic imaging system (DFIS). The THA side demonstrated an average 3.4° (±6.5°, range: -5.9° to 15.2°) greater internal rotation than the contralateral native hip, during the step-up activity but not during leg stance. The difference in internal rotation was highly correlated to the difference in femoral anteversion and anterior translation of hip joint center between implanted and native hip (R(2)  = 0.71, p < 0.01). The results suggest the importance of accurate THA component placement in restoring normal hip kinematics during functional activities.
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Dimitris
authors: D
authors: Dimitriou
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Tsung-Yuan
authors: TY
authors: Tsai
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Jing-Sheng
authors: JS
authors: Li
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.|Department of Orthopedic Surgery, Jeju National University, School of Medicine, Jeju, South Korea.
authors: Kwang Woo
authors: KW
authors: Nam
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.|Department of Orthopedic Surgery, Yonsei University, College of Medicine, Seoul, South Korea.
authors: Kwan Kyu
authors: KK
authors: Park
authors: Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Young-Min
authors: YM
authors: Kwon
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011859:Radiography
keywords: biomechanics; component orientation; in vivo kinematics; step-up; total hip arthroplasty