A three-dimensional dynamic model of the tibiofemoral and patellofemoral articulations was developed to predict the motions of knee implants during a step-up activity. Patterns of muscle activity, initial joint angles and velocities, and kinematics of the hip and tinkle were measured experimentally and used as inputs to the simulation. Prosthetic knee kinematics were determined by integration o...

Saddle position affects mechanical variables during submaximal cycling, but little is known about its effect on mechanical performance during maximal cycling. Therefore, this study relates saddle position to experimentally obtained maximal power output and theoretically calculated moment generating capacity of hip, knee and ankle muscles during isokinetic cycling. Ten subjects performed maximal...

We quantify how the hip energetics and knee torque required for an above-knee prosthesis user to walk with the kinematics of able-bodied humans vary with the inertial properties of the prosthesis. We also select and optimize passive mechanical components for a prosthetic knee to accurately reproduce the required knee torque. Previous theoretical studies have typically investigated the effects o...

Kinematics in osteoarthritic knees may be impeding efforts to reproduce "normal" knee kinematics in the prosthetic knee. Fourteen subjects with unilateral symptomatic knee osteoarthritis performed a supine leg press from 0 degrees to 90 degrees flexion against a 150-N load. The tibiofemoral contact pattern was recorded for both knees using sagittal T1-weighted magnetic resonance imaging. Severi...

The pivot shift test is the only clinical test that has been shown to correlate with subjective criteria of knee joint function following rupture of the anterior cruciate ligament. The grade of the pivot shift is important in predicting short- and long-term outcome. However, because this grade is established by a clinician in a subjective manner, the pivot shift's value as a clinical tool is re...

The goal of this study was to determine whether single-tunnel-double-bundle-equivalent posterior cruciate ligament (PCL) reconstruction using an aperture femoral fixation device better replicated normal knee kinematics than single-bundle reconstruction. Eight fresh-frozen human cadaver knees underwent arthroscopically assisted PCL reconstruction and were examined with a robotic testing system t...

STUDY DESIGN Randomized controlled trial. OBJECTIVE To determine if the addition of real-time feedback (RTF) to postresponse feedback (PRF) improves jump-landing kinematics compared to PRF alone and a no-feedback control group. BACKGROUND Injury-prevention programs to reduce risk of anterior cruciate ligament injury have shown promising results in altering jump-landing biomechanics. Real-ti...

Our research aims to design low-cost, high-performance, passive prosthetic knees for developing countries. In this study, we determine optimal stiffness, damping, and engagement parameters for a low-cost, passive prosthetic knee that consists of simple mechanical elements and may enable users to walk with the normative kinematics of able-bodied humans. Knee joint power was analyzed to divide ga...

BACKGROUND Our aim was to evaluate the outcomes of combined hamstring release and rectus transfer in children with crouch gait using physical examination and gait analysis. MATERIALS AND METHODS A total of 19 patients (38 knee joints) with crouch were evaluated by static examination and computerized analysis with dynamic EMG. The Ely test was positive together with prolonged and increased act...

We quantify how the hip energetics and knee torque required for an above-knee prosthesis user to walk with the kinematics of able-bodied humans vary with the inertial properties of the prosthesis. We also select and optimize passive mechanical components for a prosthetic knee to accurately reproduce the required knee torque. Previous theoretical studies have typically investigated the effects o...