Image based weighted center of proximity versus directly measured knee contact location during simulated gait.
To understand the mechanical consequences of knee injury requires a detailed analysis of the effect of that injury on joint contact mechanics during activities of daily living. Three-dimensional (3D) knee joint geometric models have been combined with knee joint kinematics to dynamically estimate the location of joint contact during physiological activities-using a weighted center of proximity (WCoP) method. However, the relationship between the estimated WCoP and the actual location of contact has not been defined. The objective of this study was to assess the relationship between knee joint contact location as estimated using the image-based WCoP method, and a directly measured weighted center of contact (WCoC) method during simulated walking. To achieve this goal, we created knee specific models of six human cadaveric knees from magnetic resonance imaging. All knees were then subjected to physiological loads on a knee simulator intended to mimic gait. Knee joint motion was captured using a motion capture system. Knee joint contact stresses were synchronously recorded using a thin electronic sensor throughout gait, and used to compute WCoC for the medial and lateral plateaus of each knee. WCoP was calculated by combining knee kinematics with the MRI-based knee specific model. Both metrics were compared throughout gait using linear regression. The anteroposterior (AP) location of WCoP was significantly correlated with that of WCoC on both tibial plateaus in all specimens (p<0.01, 95% confidence interval of Pearson׳s coefficient r>0), but the correlation was not significant in the mediolateral (ML) direction for 4/6 knees (p>0.05). Our study demonstrates that while the location of joint contact obtained from 3D knee joint contact model, using the WCoP method, is significantly correlated with the location of actual contact stresses in the AP direction, that relationship is less certain in the ML direction.
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Hongsheng
H
Wang
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Tony
T
Chen
Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY, USA.
Matthew F
MF
Koff
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Ian D
ID
Hutchinson
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Susannah
S
Gilbert
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Dan
D
Choi
Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, NY 10021, USA.
Russell F
RF
Warren
Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, NY 10021, USA.
Scott A
SA
Rodeo
Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA. Electronic address: mahers@hss.edu.
Suzanne A
SA
Maher
D000203:Activities of Daily Living; D000328:Adult; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005269:Femur / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007718:Knee Injuries; D007719:Knee Joint / Q000502:physiology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D013977:Tibia / Q000502:physiology*; D016138:Walking / Q000502:physiology
3D knee model; Cartilage contact; Tibiofemoral contact; Weighted center