Comparing Functional and Anatomic Reference Planes with Variations in Pelvic Tilt

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Many surgeons wonder: which type of patient reference plane leads to better accuracy during navigation – functional or anatomic? A key consideration for this topic is: how do these reference planes cope with variation in pelvic tilt in the patient population? Watch this slideshow to find out why a functional reference plane is better than an anatomic reference plane for accommodating variations in patient pelvic tilt for supine hip replacement.

In the slideshow, we use data from a study of 1517 patients1 to illustrate the differences between functional and anatomic reference planes. These patients were from consecutive Australian surgeries in 2014 and 2015, with an average patient age of 63 years and with 53% male, 47% female. Appropriate caution should be used in applying the learnings from this patient group to other patient demographics.

If you would like to see how this theory translates to practice, see our clinical results comparing the accuracy of functional and anatomic reference planes2.


  1. Pierrepont J, Walter L, Miles B, et al. Pelvic tilt in the standing, supine and seated positions. Orthopaedic Proceedings 2016;98-B(SUPP_9):30-30. doi: 10.1302/1358-992X.98BSUPP_9.ISTA2015-030
  2. Farey J, Chai Y, Xu J, et al. Evaluating alternative registration planes for imageless, computer-assisted navigation during supine total hip arthroplasty. Orthopaedic Proceedings 2021;103-B(SUPP_14):9-9. doi: 10.1302/1358-992X.2021.14.009