Correlation between trochlear dysplasia and the notch index

J Orthop Surg (Hong Kong). 2013 Dec;21(3):290-3. doi: 10.1177/230949901302100305.

Abstract

Purpose: To evaluate the correlation between trochlear dysplasia and the notch index.

Methods: Magnetic resonance images (MRI) of 95 knees in 54 male and 36 female patients aged 4 to 74 (mean, 28) years were reviewed by 2 musculoskeletal radiologists. Standard MRI sequences were used. Based on the Dejour classification of trochlear dysplasia, the knees were classified into normal or types A, B, C, and D. A notch index of <0.2 was considered narrow. Normal knees and knees with trochlear dysplasia were compared.

Results: 60 of the 95 knees had trochlear dysplasia, of which 39 were Dejour type A, 13 were type B, 7 were type C, and one was type D. Dejour types B, C, and D were combined as non-type A. Inter-observer agreement in assessing the notch index was good (Kappa=0.6). The mean notch indices in normal knees and knees with trochlear dysplasia were comparable (0.161 vs. 0.157, p=0.18), as were in Dejour type A and non-type A knees (0.154 vs. 0.160, p=0.54) and in Dejour types A, B, C, and D knees (0.154 vs. 0.165 vs 0.153 vs. 0.2, p=0.17-0.7). The rate of ACL injuries was similar in patients with normal knees and those with type-A trochlear dysplasia. A low notch index (narrow notch) was not associated with ACL injury.

Conclusion: The notch index and trochlear morphology are 2 independent entities. A narrow notch does not imply a shallow trochlear grove.

Keywords: anterior cruciate ligament; knee injuries.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anterior Cruciate Ligament / pathology
  • Anterior Cruciate Ligament Injuries*
  • Child
  • Child, Preschool
  • Female
  • Femur / abnormalities*
  • Humans
  • Knee Injuries / diagnosis*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Patellofemoral Joint / abnormalities*
  • Severity of Illness Index
  • Young Adult