Patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing

Atsushi Takahashi, Hirotaka Sano, Masahiro Ohnuma, Mitsuhiro Kashiwaba, Daisuke Chiba, Masayuki Kamimura, Takehiko Sugita, Eiji Itoi

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Purpose: The objective of this study was to determine the effect of patellar morphology and implant design on patellofemoral contact stress in total knee arthroplasty (TKA) without patellar resurfacing. Methods: Radiographic investigation: One hundred and fifty-seven knees of 127 patients were included in the study. Implants used in the present series were Low Contact Stress (LCS), Genesis II and NexGen. The relationship between the pre-operative patellar facet angle and newly identified post-operative osteosclerosis was assessed. Finite element analysis: Using patient-specific patellar three-dimensional finite element models, the relationship between the patellar facet angle and mean von Mises stress within the patella was calculated at flexion angles of 15°, 45°, 75° and 105°. Results: Radiographic investigation: Post-operative osteosclerosis was observed with decreasing patellar facet angle in the Genesis II (odds ratio = 0. 72; 95% confidence interval, 0. 55-0. 93; P = 0. 012) and NexGen implants (odds ratio = 0. 87; 95% confidence interval, 0. 77-0. 99; P = 0. 029). Patients treated with the Genesis II had significantly more advanced osteosclerosis than those treated with the other two implants. Finite element analysis: A negative correlation was found between the patellar facet angle and the mean von Mises stress for all three implants. The Genesis II showed significantly higher von Mises stress than the other two implants at flexion angles of 15°, 45° and 105°. Conclusions: Both patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing. Level of evidence: Case control study, Level III.

Original languageEnglish
Pages (from-to)1787-1795
Number of pages9
JournalKnee Surgery, Sports Traumatology, Arthroscopy
Volume20
Issue number9
DOIs
Publication statusPublished - 2012 Aug 1

Keywords

  • Finite element analysis
  • Patellar morphology
  • Patellofemoral contact pressure
  • Total knee arthroplasty

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

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