Elsevier

The Journal of Arthroplasty

Volume 25, Issue 6, September 2010, Pages 920-925
The Journal of Arthroplasty

Mobile-Bearing Total Knee Arthroplasty Improves Patellar Tracking and Patellofemoral Contact Stress: In Vivo Measurements in the Same Patients

https://doi.org/10.1016/j.arth.2009.07.024Get rights and content

Abstract

Controversies exist in clinical study concerning the effect of rotating platform on patellar tracking. The aim of this in vivo study was to compare tibial rotation, patellar tracking, and patellofemoral contact stress in mobile and fixed-bearing platform intraoperatively in the same knee. Sixty-six knees of posterior-stabilized total knee prostheses were evaluated using a computed tomography–guided navigation system. Medial shift and lateral tilt of patella were significantly smaller in mobile knee. Averaged maximum contact stress was significantly smaller in mobile knee than fixed knee. However, tibial rotation during flexion has no significant difference. This study showed that mobile platform total knee arthroplasty significantly improved patellar tracking and decreased patellofemoral contact stress.

Section snippets

Methods

Sixty-six osteoarthritic knees from 56 female and 10 male with mean age of 69.6 ± 8.6 years underwent a unilateral primary posterior-stabilized total knee prostheses (PFC Sigma RP-F; DePuy, Warsaw, Ind) between 2006 and 2008. Among these patients, coronal plane alignment was 10.0° ± 5.53° in varus preoperatively. There were neither patients with valgus knee nor severe bony defects in the present study. Surgery was performed by single surgeon using subvastus approach to eliminate the influence

Results

Tibial rotation from extension to flexion of the knee has no significant difference between fixed knee (6.93° ± 3.54°) and mobile knee (7.83° ± 3.89°) (Table 1). Medial shift of patella occurs in proportion to knee flexion in all knees. Medial shift of patella was significantly larger in fixed knee (4.20 ± 1.73 mm) than that in mobile knee (3.35 ± 1.51 mm) (P < .05). Lateral tilt of patella increased during knee flexion in both of the bearing. In fixed knee, lateral tilt angle is significantly

Discussion

Rotation of the rotating platform polyethylene insert with the femoral component, independent of the rotation of the firmly fixed tibial tray, should reduce stresses transmitted to the fixation interface between component and bone and create the potential for self-alignment of the polyethylene bearing with the femoral component. Self-alignment is advantageous for optimal TKA kinematics and for maintenance of acceptable polyethylene surface stresses and stresses exerted on posterior

References (13)

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Cited by (41)

  • Mobile-bearing insert reduced patellar contact force at knee flexion during posterior stabilized total knee arthroplasty

    2020, Clinical Biomechanics
    Citation Excerpt :

    In fixed-bearing TKA, if substantial internal fixation of the tibial component is present, the tibial tubercle is lateralized relative to the femoral component, enhancing the risk of patellar subluxation. A rotating platform design, through bearing rotation, permits greater self-correction of component rotational malalignment, allowing better centralization of the extensor mechanism (Sawaguchi et al., 2010). Rees et al. reported that the PF kinematics of mobile-bearing TKAs more closely resembled the normal knee than that of fixed-bearing TKAs (Rees et al., 2005).

  • The influence of intraoperative soft tissue balance on patellar pressure in posterior-stabilized total knee arthroplasty

    2016, Knee
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    Previous in vitro studies indicated that patellar resurfacing decreased the patellar contact area and increased patellar pressure and shear stress [16–19]. Majima and colleagues recently reported using a pressure sensor intraoperatively, and found that a mobile-bearing insert, intraoperative medial pivot pattern, and external rotation of the femoral component decreased PF contact stress [20–22]. However, the relationship between intraoperative soft tissue balance and patellar pressure has not been investigated.

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No benefits or funds were received in support of the study.

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