KNEE
Measurements of knee morphometrics using MRI
and arthroscopy: a comparative study between ACL-injured
and non-injured subjects
Sharon H. A. Vrooijink
•
Femke Wolters
•
Carola F. Van Eck
•
Freddie H. Fu
Received: 3 February 2011 / Accepted: 21 March 2011 / Published online: 7 April 2011
Ó Springer-Verlag 2011
Abstract
Purpose The primary purpose of this study was as follows:
(1) to compare bony morphology in subjects with and
without ACL injury. The secondary purposes were the fol-
lowing: (2) to compare bony morphology between men and
women and (3) to determine whether MRI measurements of
the notch correlate with intra-operative measurements.
Methods MRI measurements of NW, bicondylar width,
medial condyle size and lateral condyle size, and medial-
to-lateral condyle ratio (M:L) were taken from 45 subjects
with ACL injury and 44 subjects without ACL injury, by
two independent observers. In addition, notch width mea-
surements were taken arthroscopically in the 45 injured
subjects. Knee morphometrics were compared between
men and women. Additionally, values of ACL-injured and
non-injured subjects were compared for male and female
subjects separately. Correlations between notch measure-
ments taken from MRI and measured arthroscopically were
determined. Reliability of the MRI measurements was
calculated.
Results Significant differences were found for bicondylar
width (P = 0.001), medial condyle width (P = 0.002), and
lateral condyle width (P = 0.002) between male and
female subjects. When bony morphology was compared
between ACL-injured and non-injured subjects, the male
subjects showed significant differences for bicondylar
width (P = 0.002) and medial condyle width (P = 0.008).
For the female subjects, significant differences were found
for bicondylar width (P = 0.009) and lateral condyle width
(P = 0.002). There was no correlation between notch
width measured on the MRI’s and NW measured intra-
operatively. The intra- and inter-observer reliability of the
MRI measurements was satisfactory.
Conclusions There were differences in bony morphology
between men and women and between subjects with and
without ACL injury. The bony morphology that was dif-
ferent between ACL-injured and non-injured subjects var-
ied between male and female subjects.
Level of evidence Case–control study, Level III.
Keywords ACL Á Morphometrics Á Notch Á Gender
Introduction
Some people are at greater risk of tearing their ACL than
others. In general, women have a higher injury risk compared
with men [6, 12, 17, 18]. Several studies have tried to identify
risk factors contributing to ACL injury with different results.
Factors that have been proposed to contribute in the devel-
opment of an ACL tear are notch width (NW) and notch
width index (NWI), but the results of studies on this topic are
not unanimous [9, 13, 19–23]. Possible explanations for the
differences in outcomes are the fact that these were cadaver
studies, a small study population or because of the variation
in methods used to measure the notch. Besides notch size, the
relationship between other bony morphologic characteristics
could influence ACL injury risk. For example, the size of the
femoral condyles and the ratio between medial and femoral
condyle size. Differences in medial-to-lateral femoral con-
dyle size ratio, change the amount of rotation of the knee,
S. H. A. Vrooijink Á F. Wolters Á C. F. Van Eck Á F. H. Fu (&)
Department of Orthopaedic Surgery, University of Pittsburgh
Medical Center, Kaufmann Bldg Ste 1011, 3471 Fifth Ave,
Pittsburgh, PA 15213-3221, USA
e-mail: ffu@upmc.edu
S. H. A. Vrooijink Á F. Wolters
University of Nijmegen, School of Medicine,
Nijmegen, The Netherlands
123
Knee Surg Sports Traumatol Arthrosc (2011) 19 (Suppl 1):S12–S16
DOI 10.1007/s00167-011-1502-4