In vivo contact kinematics and contact forces of the knee after total knee arthroplasty during dynamic weight-bearing activities

Abstract

Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous, in vivo measurement of tibiofemoral articular contact forces and contact kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants during dynamic single leg lunge and chair risingsitting. The measured forces and contact locations were also used to determine mediolateral distribution of axial contact forces. Contact kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising-sitting (224% body weight vs. 187% body weight). In this study we measured peak anteroposterior and mediolateral forces averaging 13.3% BW, during lunge and 18.5% BW during chair rising-sitting. Mediolateral distributions of axial contact force were both patient and activity specific. All patients showed equitable medial-lateral loading during lunge but greater loads at the lateral compartment during chair rising-sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs.

Response to the Letter to the Editor—Comments on “Validation of a non-invasive fluoroscopic imaging technique for the measurement of dynamic knee motion”

“…We concluded in the manuscript that the accuracy in recreating dynamic motion might indeed decrease with increasing velocity. More recently the high accuracy of the dual fluoroscopic technique was validated using cadaveric knees and a robotic testing system for speeds up to 0.5 m/s and the technique was successfully applied to study of TKA kinematics during dynamic lunge and chair rising/sitting activities (Varadarajan et al, 2008). Without doubt, we agree that the restriction of motion analysis to activities performed at moderate velocity is a limitation of the system as clearly indicated in our paper.…”

“…This was also the primary objective of our paper. In this regard we would also like to direct readers to our recent study of dynamic weight-bearing activities following TKA (Varadarajan et al, 2008).…”

“…This can be done without compromising accuracy when analyzing clinically relevant daily activities at moderate velocity (stair ascent/descent, lunge, chair rising/sitting, treadmill gait, etc.). It is for these reasons that fluoroscopy has been validated and used by various research centers to study dynamic knee joint motion (Stiehl et al, 1995;Banks and Hodge, 1996;Komistek et al, 2003;Zihlmann et al, 2006;Varadarajan et al, 2008). Fig.…”

The 2011 ABJS Nicolas Andry Award: ‘Lab’-in-a-Knee: In Vivo Knee Forces, Kinematics, and Contact Analysis

“…Previously reported knee forces and fluoroscopic kinematics measured during walking, stair ascent, dynamic single-leg lunge, and chair rising-sitting were used to evaluate the inverse finite element optimization algorithm [13,55,61]. From each implanted subject, 10 different force and kinematic vectors were selected.…”

A novel multi-planar radiography method for three dimensional pose reconstruction of the patellofemoral and tibiofemoral joints after arthroplasty

“…Conventional bi-planar fluoroscopy cannot generally be used to measure patellofemoral kinematics after knee arthroplasty, although this method has been used to accurately measure the kinematics of the natural tibiofemoral (TF) and PF joints (Asano et al, 2001;Valstar et al, 2001;You et al, 2001;Kaptein et al, 2003;Varadarajan et al, 2008;Suggs et al, 2009). The challenge with the PF joint after arthroplasty is that the patellar component is only visible (and not even fully visible) in a projection that is sagittal or slightly deviated from the sagittal plane; otherwise it is obscured by the projection of the metal femoral component.…”