Do ethnicity and gender influence posterior tibial slope?
BACKGROUND
Ethnicity and gender can affect posterior tibial slope; however, studies on this topic have limitations and are in disagreement. The aim of the present study was to evaluate posterior tibial slope in a large group of consecutive patients, determining whether ethnicity and gender can influence its value. Secondly, to determine intra- and inter-rater reliability of the two radiographic methods adopted.


METHODS
Posterior tibial slope was calculated (rater 1) in lateral view X-rays of the knee according to the posterior tibial cortex (PTC) and tibial proximal anatomical axis (TPAA) methods. Data were matched with ethnicity and gender. For determination of intra- and inter-rater reliability, 50 random X-rays were selected, and blindly measured by two other raters (2 and 3).


RESULTS
A total of 581 radiographs were included (413 white and 168 black knees). Comparing white and black subjects, a statistically significant difference was found for both PTC (4.9 ± 1.2 vs 7.1 ± 2.9, p < 0.0001), and for TPAA (7.7 ± 1.1 vs 10.2 ± 3.0, p < 0.0001). In white subjects, an influence of gender was found only for TPAA (6.4 ± 1.1 in males vs 7.6 ± 1.1 in females, p < 0.0001). In black subjects, an influence of gender was found only for PTC (7.4 ± 3.0 in males vs 6.2 ± 2.9 in females, p = 0.01). Intra-rater reliability was good for both methods for rater 1, and very good for rater 2. Inter-rater reliability among the 3 raters was very good for both methods.


CONCLUSIONS
Differences in posterior tibial slope between different ethnic groups exist. Differences observed between genders are conflicting and might be too small to have implications in clinical practice. The TPAA method is recommended for the evaluation of posterior tibial slope because of higher intra- and inter-rater reliability. Level of evidence 3 Case-control study.
Ospedale San Pietro Fatebenefratelli, Rome, Italy.|Department of Orthopaedic Surgery, Sport Traumatology Unit, University of Rome "Tor Vergata", Viale Oxford 81, 00133, Rome, Italy.
Salvatore
http://orcid.org/0000-0002-4019-4810
S
Bisicchia
Department of Orthopaedic Surgery, Sport Traumatology Unit, University of Rome "Tor Vergata", Viale Oxford 81, 00133, Rome, Italy.
Gavinca M
GM
Scordo
Life Little Company of Mary Hospital, Pretoria, South Africa.
Johan
J
Prins
Department of Orthopaedic Surgery, Sport Traumatology Unit, University of Rome "Tor Vergata", Viale Oxford 81, 00133, Rome, Italy. cosimo.tudisco@uniroma2.it.
Cosimo
C
Tudisco
D000328:Adult; D044383:Black People; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012737:Sex Factors; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D044465:White People
Ethnicity; Gender; Knee; Tibial slope