Does unicondylar knee arthroplasty affect tibial bone strain? A paired cadaveric comparison of fixed- and mobile-bearing designs
Background Unexplained pain in the medial proximal tibia frequently leads to revision after unicondylar knee arthroplasty (UKA). As one of the most important factors for osteogenic adaptive response, increased bone strain following UKA has been suggested as a possible cause. Questions/purposes In this study we: (1) performed a cadaver-based kinematic analysis on paired cadaveric specimens before and after mobile-bearing and fixed-bearing UKA; and (2) simultaneously characterized the strain distribution in the anterior and posterior proximal tibia during squatting. Methods Five pairs of fresh, frozen full-leg cadaver specimens (four male, one female, 64 years to 87 years) were subjected to a dynamic squatting motion on a kinematic rig to simulate joint loading for a large ROM. Forces were applied to the quadriceps and hamstrings during the simulation while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Tibial cortical bone strain was measured with stacked strain gauge rosettes attached at predefined anterior and posterior positions on the medial cortex. Pairwise implantation of mobile-bearing (UKA(MB)) and fixed-bearing implants (UKA(FB)) allowed a direct comparison of right and left knees from the same donor through a linear mixed model. Results UKA(MB)more closely replicated native kinematics in terms of tibial rotation and in AP and mediolateral translation. Maximum principal bone strain values were consistently increased compared with native (anteromedial, mean [+/- SD] peak strain: 311 mu epsilon +/- 190 and posterior, mean peak strain: 321 mu epsilon +/- 147) with both designs in the anteromedial (UKA(FB), mean peak strain: 551 mu epsilon +/- 381, Cohen's d effect size 1.3 and UKA(MB), mean peak strain: 596 mu epsilon +/- 564, Cohen's d effect size 1.5) and posterior (UKA(FB), mean peak strain: 505 mu epsilon +/- 511, Cohen's d effect size 1.3 and UKA(MB), mean peak strain: 633 mu epsilon +/- 424, Cohen's d effect size 2.1) region. However, in the anterolateral region of the medial tibial bone, UKA(FB)demonstrated the overall largest increase in strain (mean peak strain: 1010 mu epsilon +/- 787, Cohen's d effect size 1.9), while UKA(MB)(613 mu epsilon +/- 395, Cohen's d effect size 0.2) closely replicated values of the native knee (563 mu epsilon +/- 234). Conclusion In this in vitro cadaver study both UKA(MB)and UKA(FB)led to an increase in bone strain in comparison with the native knee. However, in the anterolateral region of the medial tibial plateau, proximal tibial bone strain was lower after UKA(MB)and UKA(FB). Both UKA(MB)and UKA(FB)lead to comparable increases in anteromedial and posterior tibial strain in comparison with the native knee. In the anterolateral region of the medial tibial plateau UKA, proximal tibial bone strain was closer to the native knee after UKA(MB)than after UKA(FB). In an attempt to link kinematics and strain behavior of these designs there seemed to be no obvious relation.
Source (journal)
Clinical orthopaedics and related research. - Philadelphia, Pa, 1963, currens
Clinical Orthopaedics and Related Research
Source (book)
European-Knee-Society (EKS) Meeting, MAY 02-03, 2019, Valencia, SPAIN
Philadelphia, Pa : 2020
0009-921X [print]
1528-1132 [online]
478 :9 (2020) , p. 1990-2000
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Creation 19.12.2023
Last edited 20.12.2023
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