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Accuracy of cup height and medialization in THA for dysplastic hip osteoarthritis using an imageless navigation
Fumiaki Inori1, Hirotsugu Ohashi, Hirotake Yo
1Department of Orthopaedic Surgery, Osaka Saiseikai Nakatsu Hospital, Osaka, Japan.
Insights
This study introduces an imageless navigation technique for total hip arthroplasty in dysplastic hips, improving cup positioning accuracy. The system demonstrated acceptable precision for cup height and medialization in complex cases.
Area of Science:
- Orthopedic Surgery
- Medical Imaging
- Biomechanical Engineering
Background:
- Dysplastic hip osteoarthritis presents challenges in total hip arthroplasty (THA) due to bony deformities affecting acetabular component placement.
- Accurate cup height and medialization are critical for successful THA outcomes, particularly in dysplastic hips.
Purpose of the Study:
- To evaluate the efficacy of a novel imageless navigation system for precise acetabular cup placement in total hip arthroplasty for dysplastic hips.
- To assess the accuracy of navigated cup height, medialization, inclination, anteversion, and leg lengthening compared to radiographic measurements.
Main Methods:
- A prospective study involving 80 patients with dysplastic hips (Crowe types I-III) undergoing THA.
- Utilized an imageless navigation system for registration of the anterior pelvic plane and femur, followed by acetabular landmark registration (teardrop, posterior rim, medial wall).
- Navigated parameters included cup height, medialization, inclination, anteversion, and leg lengthening; accuracy was assessed against radiographic data.
Main Results:
- The system achieved acceptable accuracy for cup height (4.5 ± 4.0 mm), medialization (3.0 ± 2.5 mm), inclination (4.3° ± 3.1°), anteversion (5.5° ± 3.8°), and leg lengthening (3.7 ± 3.0 mm).
- A significant improvement in cup medialization accuracy was observed between the first 20 and last 20 cases.
- Accuracy was not significantly influenced by Crowe type or surgical position (supine vs. lateral).
Conclusions:
- The developed imageless navigation technique provides acceptable accuracy for acetabular cup height and medialization in total hip arthroplasty for dysplastic hips.
- This system offers a viable solution for improving surgical precision in complex hip osteoarthritis cases.
- Further refinement may enhance accuracy, particularly for challenging Crowe type dysplastic hips.
Abstract:
In total hip arthroplasty (THA) for dysplastic hip osteoarthritis, bony deformity makes it difficult to identify the correct cup height and medialization. The authors developed a new technique for registration and navigation of cup position for dysplastic hips using an imageless navigation system. Eighty dysplastic hips (Crowe type I, n=58; type II, n=18; type III, n=4) underwent THA. Thirty-four hips were operated on while in the supine position and 46 hips were operated on while in the lateral position. Before capsulectomy, the anterior pelvic plane and the position of the femur were registered. After exposure of the acetabulum, the teardrop, posterior rim, and medial wall of the acetabulum were registered. Then the cup height, cup medialization, cup inclination, anteversion, and leg lengthening were navigated. The difference between the navigated and radiographic cup heights was 4.5 ± 4.0 mm, the difference in cup medialization was 3.0 ± 2.5 mm, the difference in cup inclination was 4.3° ± 3.1°, the difference in cup anteversion was 5.5° ± 3.8°, and the difference in leg lengthening was 3.7 ± 3.0 mm. Comparison of the first 20 cases with the last 20 cases showed that the accuracy of cup medialization was significantly improved. These differences were not affected by Crowe type or surgical position. Because the correct cup height and medialization are key issues in THA for dysplastic hip osteoarthritis, the accuracy of cup height and medialization in this imageless navigation system were acceptable for clinical application.
