Medial Unicondylar Knee Arthroplasty Improves Patellofemoral Congruence: a Possible Mechanistic Explanation for Poor Association Between Patellofemoral Degeneration and Clinical Outcome

J Arthroplasty. 2015 Nov;30(11):1917-22. doi: 10.1016/j.arth.2015.05.034. Epub 2015 May 23.

Abstract

The purpose was to determine the effect of medial fixed bearing unicondylar knee arthroplasty (UKA) on postoperative patellofemoral joint (PFJ) congruence and analyze the relationship of preoperative PFJ degeneration on clinical outcome. We retrospectively reviewed 110 patients (113 knees) who underwent medial UKA. Radiographs were evaluated to ascertain PFJ degenerative changes and congruence. Clinical outcomes were assessed preoperatively and postoperatively. The postoperative absolute patellar congruence angle (10.05 ± 10.28) was significantly improved compared with the preoperative value (14.23 ± 11.22) (P = 0.0038). No correlation was found between preoperative PFJ congruence or degeneration severity, and WOMAC scores at two-year follow up. Pre-operative PFJ congruence and degenerative changes do not affect UKA clinical outcomes. This finding may be explained by the post-op PFJ congruence improvement.

Keywords: clinical follow-up; congruence; fixed bearing; patellofemoral joint; unicondylar knee arthroplasty.

MeSH terms

  • Aged
  • Arthroplasty, Replacement, Knee / statistics & numerical data*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / surgery
  • Patella / diagnostic imaging
  • Patella / physiology
  • Patellofemoral Joint / diagnostic imaging
  • Patellofemoral Joint / physiology*
  • Radiography
  • Retrospective Studies