Neither lateral patellar facet nor patellar size are altered in patellofemoral unstable patients: a comparative magnetic resonance imaging analysis

Alexander Otto, Philippe M. Tscholl, Reedik Pääsuke, Elmar Herbst, Lukas Willinger, Andreas B. Imhoff, P. U. Brucker

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Purpose: It remains unclear if morphologic patterns of the patella itself predispose to patellar instability. This study examined established patellar landmarks in relation to the femoral condyle width to clarify differences of patellar morphologies in patellofemoral stable and unstable patients. Methods: Magnetic Resonance Imaging of 50 subjects (20.7 ± 4.4 years; 17 males, 33 females) with patellofemoral instability (study group, SG) and 50 subjects (25.3 ± 5.8 years; 31 males, 19 females) with anterior cruciate ligament rupture (control group, CG) were analyzed. Corresponding patellar value indices (PW-I; LPF-I 1; LPF-I 2) in relation to the femoral condyle width (FCW) were evaluated after the measurement of absolute patellar dimension [patellar width (PW); direct length of the lateral patellar facet (LPF-1); projected length of the lateral patellar facet (LPF-2)]. The patellar shape according to Wiberg, trochlear dysplasia, patellar height, and tibial tubercle–trochlear groove (TT–TG) distance were determined. Results: The SG showed a significantly longer absolute (LPF 2) (P = 0.041) and relative (LPF-I 1, LPF-I 2) (P < 0.001) lateral facet of the patella. No significant differences were evaluable for the relative patellar width (PW-I) (ns). A patellar shape type 3 (P = 0.001) as well as a higher position of the patella and TT–TG-distance (P < 0.001) were significantly more often present in the SG. Conclusion: There are several bony alterations associated with patellofemoral instability, but our data did not show a significantly smaller lateral patellar facet or relative patellar width that could facilitate a patellar dislocation. This helps surgeons, that are considering to surgically address the patella in cases of patellofemoral instability, to better understand its morphologic pattern. Level of evidence: III.

Original languageEnglish
Pages (from-to)1064-1071
Number of pages8
JournalKnee Surgery, Sports Traumatology, Arthroscopy
Volume28
Issue number4
DOIs
StatePublished - 1 Apr 2020

Keywords

  • Patella
  • Patellar dysplasia
  • Patellar facet
  • Patellar morphology
  • Patellar size
  • Patellofemoral instability
  • Trochlear dysplasia

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