In-vivo 6 degrees-of-freedom kinematics of metal-on-polyethylene total hip arthroplasty during gait.
Knowledge of accurate in-vivo 6 degree-of-freedom (6-DOF) kinematics of total hip arthroplasty (THA) during daily activities is critical for improvement of longevity of the components. Previous studies assessed in-vivo THA kinematics using skin marker-based motion analysis. However, skin markers are prone to move with respect to the underlying bones. A non-invasive dual fluoroscopic imaging system (DFIS) based tracking technique has been used to avoid skin artifacts and provide accurate 6-DOF kinematic measurement. This study aimed to quantify in-vivo 6-DOF THA kinematics during gait using DFIS. Twenty eight well-functioning THAs were evaluated during treadmill gait under DFIS surveillance. The maximum translations of the femoral head were 0.46±0.10mm and 0.45±0.10mm during the stance and swing phases (p=0.57), respectively. The range of hip flexion was from 8.7° to 47.6°, adduction from 3.0° to 12.5° and external rotation from 19.2° to 29.7°. The THA was flexed, externally rotated and adducted throughout the gait. The magnitudes of the femoral head translations were found to be within the manufacture tolerance of the components, suggesting that in-vivo hip "pistoning" during gait cycle may be minimal in well-functioning THAs. The 6-DOF kinematics could be used as the baseline knowledge for further improvement of wear-testing of hip implant, implants manufacturing and implant positioning during surgery.
Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
Tsung-Yuan
TY
Tsai
Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
Jing-Sheng
JS
Li
Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
Shaobai
S
Wang
Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
Donna
D
Scarborough
Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA. Electronic address: ymkwon@mgh.harvard.edu.
Young-Min
YM
Kwon
D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006615:Hip / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D020959:Polyethylene; D011859:Radiography; D016059:Range of Motion, Articular; D012399:Rotation; D016138:Walking / Q000502:physiology
D008670:Metals; D020959:Polyethylene
Fluoroscope; Gait; Kinematics; Total hip arthroplasty; in vivo