Pelvic Tilt Angle Differences Between Symptom-Free Young Subjects and Elderly Patients Scheduled for THA: The Rationale for Tilt-Adjusted Acetabular Cup Implantation
Carlos J. Marques1, *, Tobias Martin2, 6, Andrzej Kochman7, Adrian Goral6, Frank Lampe4, 5, Viktor Breul3, Josef Kozak2, 6
1 Research Center of the Orthopaedic and Joint Replacement Department at the Schoen Klinik Hamburg Eilbek, Dehnhaide 120, D-22081 Hamburg, Germany
2 Navigation Lab, Aesculap AG, Am Aesculap-Platz, D-78532 Tuttlingen, Germany
3 Medical Scientific Affairs, Aesculap AG, Am Aesculap-Platz, D-78532 Tuttlingen, Germany
4 Orhtopaedic and Joint Replacement Department at the Schoen Klinik Hamburg Eilbek, Dehnhaide 120, D-22081 Hamburg, Germany
5 Faculty of Life Sciences at the Hamburg University of Applied Sciences, Lohbrügger Kirchstraße 65, D-21033 Hamburg, Germany
6 AGH University of Science and Technology, Krakow, Poland
7 Trauma and Orthopedic Department, Hospital of the Ministry of Internal Affairs, Wroclaw, Poland
The question whether Pelvic Tilt (PT) angles measured in the supine position are adequate for the alignment of the acetabular cup without an adjustment for anatomical differences between patients is of clinical importance. The aim of this work was to test for factors that can significantly affect PT angles.
In the present retrospective cohort comparison, the PT angles of 12 Symptom-Free Young Subjects (SFYS) and 45 patients scheduled for Total Hip Arthroplasty (THA) were compared. The data was collected during two studies with the use of a novel smartphone-based navigated ultrasound measurement system. Multi-factorial analysis of variance was run to determine which factors significantly affect PT.
Body position (F= 126.65; P< 0.001) and group (SFYS vs. THA patients) (F= 17.52; P< 0.001) had significant main effects on PT. There was also a significant interaction between body position and group (F= 25.59; P< 0.001). The mean PT increased by 8.1° from an interiorly to a neutral tilted position (P< 0.001) and 21.4° from a neutral to a posteriorly tilted position (P< 0.001) with the transition from the supine into the upright position for the SFYS and THA patients, respectively.
In both groups, PT changed significantly with a transition from the supine to the upright position. A position-dependent mean PT increase in the patient group showed that acetabular cup alignment based on PT in the supine position is not reliable without taking into consideration the inclination of the pelvis in standing position. This may lead to instability and dislocations.
Keywords: Ultrasonography, Computer assisted surgery, Total hip replacement, Anterior pelvic plane, Pelvic tilt, Hip arthroplasty (THA).
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* Address correspondence to this author at the Research Center of the Orthopaedic and Joint Replacement Department at the Schoen Klinik Hamburg Eilbek, Dehnhaide 120, D-22081 Hamburg, Germany; Tel: +4940 2092 1557; Fax: +4940 2092 1227; E-mail: firstname.lastname@example.org