gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019)

22. - 25.10.2019, Berlin

Navigated cup placement in total hip arthroplasty is more precise and accurate than free-hand technique – a prospective and randomized study

Meeting Abstract

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  • presenting/speaker Rene Mihalic - Valdoltra Orthopaedic Hospital, Ankaran, Slovenia
  • Jurij Zdovc - University of Ljubljana, Faculty of Pharmacy, Ljubljana, Slovenia
  • Rihard Trebse - Valdoltra Orthopaedic Hospital, Ankaran, Slovenia

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019). Berlin, 22.-25.10.2019. Düsseldorf: German Medical Science GMS Publishing House; 2019. DocIN39-906

doi: 10.3205/19dkou713, urn:nbn:de:0183-19dkou7130

Veröffentlicht: 22. Oktober 2019

© 2019 Mihalic et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe http://creativecommons.org/licenses/by/4.0/.


Gliederung

Text

Objectives: In the total hip arthroplasty (THA) the gold standard for component placement is still free-hand technique. The reality of such technique is, that up to 75% of cups are placed out of the safe zone, and thus prone to higher dislocation rates and lower survival rates of the implants. To avoid cup position inaccuracies in the future, we designed a study to investigate, if the use of the electro-magnetic navigation (EMN) system in THA is more precise and accurate than free-hand technique and how it's use affects surgical time.

Methods: Study was approved by National Ethics Committee. The inclusion criteria were: hip osteoarthritis, patient's consent, age higher than 18 years and no previous surgery on the affected hip joint. Patients were randomly assigned to the test (EHIP) and to the control group. In the EHIP group, anterior pelvic plane (APP) was defined immediately before skin incision, with the help of EMN and specially designed hardware tool. In all patients THA was performed through Hardinge approach and cement-less cups of the same producer were implanted. In the EHIP group, cups were implanted with the help of EMN, which provided the real-time measurement of inclination and anteversion angles. In the control group, free-hand technique was used with target angles of 42,5° and 15° for inclination and anteversion, respectively. After surgery CT scans of patient's pelvises were performed, and the true cup position was determined by an independent person. From the differences between the target angle and the true angle for every patient we calculated the mean bias error (ME) and root mean squared error (RMSE). Time of surgery was compared using two-tailed independent samples t-test.

Results and conclusion: We included 42 patients in each group. In EHIP group, there were 21 females, median age was 67.1 years and median body mass index (BMI) was 29.6 kg/m2. In the control group there were 22 females, median age was 65.8 years and median BMI was 28.9 kg/m2. We observed no significant differences between groups with respect to sex (p=0.83), age (p=0.62) and BMI (p=0.53). ME of inclination were 1.7° and 1.9° in the EHIP group and control group, respectively and ME of anteversion were -1.7° and -4.5° in the EHIP group and control group, respectively (p<0.01). RMSE for inclination were 4.6 and 6.5° in the EHIP group and control group, respectively and RMSE for anteversion were 2.8° and 8.0° in the EHIP group and control group, respectively (p<0.01). Median time of surgery was 70.4 minutes and 69.6 minutes in the EHIP group and control group, respectively (p=0.78).

We proved that the EMN is more precise and accurate than free-hand technique, especially with respect to cup anteversion. Furthermore, there was no apparent significant difference of surgical time comparing both groups. Use of EMN systems is recommended for anatomically complex cases or in minimally invasive procedures, where surgical land marks are difficult to define.