Comparison of Knee Kinematics and Kinetics during Stair Ascent in Single-Radius and Multiradius Total Knee Arthroplasty

Abstract

Traditionally total knee arthroplasty (TKA) design has been based on theories of the movement of the healthy knee joint. Currently, there are two competing theories on the flexion/extension axis of rotation of the knee with disparate radii of rotation, and thus differing movement patterns. The purpose of our study was to compare stair ascent kinematics and kinetics of single-radius (SR) and multiradius (MR) TKA subjects. We hypothesized that the knee kinematics and kinetics of SR TKA patients would more closely replicate healthy age matched controls during stair ascent than MR TKA patients, 1 year after TKA. Both patient groups had large improvements in biomechanical and clinical outcome measures following surgical intervention. However, the SR knee design performs closer to healthy controls than MR knees during stair ascent, supporting results that have been previously obtained for level walking. SR TKA subjects demonstrated reduced power production and sagittal moment compared with controls, albeit more than MR TKA subjects. This study demonstrates that patients who receive SR TKA have kinematics more closely aligned to normal patterns postoperatively than those who received an MR TKA. The power production and sagittal moment of the healthy controls most closely match previously published values of younger adults, SR TKA group most closely matches older adults, while the MR TKA group has lower power production and sagittal moments than either previously published age group. This strongly suggests that the biomechanical differences found in this study are evidence of functional deficiencies. Further research is needed to determine how these deficiencies progress with patient aging.

Sagittal radius of curvature, trochlea design and ultracongruent insert in total knee arthroplasty

“…16 There are also other studies which report better knee kinematics in SR than MR TKA. 10,11,21 However, MP TKA and more recently GR TKA have been shown to more closely mimic normal knee kinematics and produce a medial pivot pattern. 13,19,22,23…”

“…24 There are biomechanical and clinical studies which have shown improved quadricep strength and function in SR TKA as compared to MR TKA. 11,21,25,26 However, a recent randomized controlled trial by Kim et al comparing SR TKA (Triathlon®, Stryker, Mahwah, New Jersey) and MR TKR (PFC Sigma®, Depuy Synthes, Warsaw, Indiana), showed no difference in quadricep strength and recovery at one year postoperatively. 27…”

Comparison of Knee Kinematics and Kinetics during Stair Descent in Single- and Multi-Radius Total Knee Arthroplasty

“…The three ADLs had similar reductions in knee extensor moment and knee power for MR subjects in comparison to age-matched controls. During stair ascent SR subjects also had reduced knee extensor moment and knee power compared with controls, 18 while SR were statistically indistinguishable from controls for level walking and stair descent. 17 Along with the reduction seen in ADL, a reduction in the internal extension moment was found during flexion/extension leg press exercises and in cadaveric knees.…”

“…Previous research in our laboratory found that the SR design TKA more closely replicates normal walking and stair ascent kinematics and kinetics than the MR design 1 year after surgery. 17,18 Specifically, knees implanted with MR TKAs had decreased knee flexion, internal extension moment, and power absorption than age-matched controls during level walking. In contrast, no significant differences were identified between 1-year postoperative SR TKAs and age-matched controls in any biomechanical parameters.…”