New combined anteversion technique in hybrid THA: cup-first procedure with CT-based navigation.

PURPOSE: Combined anteversion (CA) technique (stem-first procedure) is generally accepted as the optimal technique to attain an appropriate CA value in total hip arthroplasty (THA). However, cup anteversion is strongly influenced by the native femoral anteversion. Accordingly, anterior protrusion of the cup in the acetabulum might occur. The purpose of the present study is to investigate the achievement of the optimal CA while avoiding anterior cup protrusion and examine the significance of our new CA technique with cup-first procedure in hybrid THA. METHODS: Seventy-nine hybrid THAs with the cup-first procedure used a CT-based navigation system for cup positioning. In the preoperative planning, cup anteversion was aimed at approximately 20°. However, in actuality, sufficient cup coverage in the original acetabulum based on individual anatomy is given priority over cup placement based on CT-based planning to ensure adequate cup coverage. The target stem anteversion was determined following Widmer's mathematical formula (37.3 = femoral stem anteversion × 0.7 + cup anteversion). Cemented stem was inserted according to the target stem anteversion angle. RESULTS: Regarding the assessment of overall alignment, the calculated Widmer's CA values during surgery and postoperative CT evaluation were 34.1° ± 6.0° (range 20.7°-51.2°) and 35.1° ± 6.7° (range 21.6°-50.7°). There were 72 hips (91.1%) within 25°-50° of CA. Cup protrusion length averaged 2.0 mm ± 2.6 mm (0-8.8 mm) in the axial view and 0.4 mm ± 1.0 mm (0-3.6 mm) in the sagittal view. Cup protrusion length of more than 5 mm was indicated in 10 hips, and no hips observed more than 10 mm. CONCLUSION: Our new CA technique (cup-first procedure) with hybrid THA was able to achieve optimal CA value while avoiding anterior cup protrusion.

Curved periacetabular osteotomy using intraoperative real-time 3-dimensional computed tomography with a robotic C-arm system: A case report.

RATIONALE: Curved periacetabular osteotomy (CPO) is a procedure with excellent surgical outcome that has been proposed for patients with development dysplasia of the hip (DDH). However, the surgical outcomes depend on the surgeon's experience and proficiency. PATIENT CONCERNS: A 38-year-old female indicated she was experiencing left hip pain while walking. DIAGNOSES: The patient was diagnosed with early-stage hip osteoarthritis due to DDH. INTERVENTIONS: The patient underwent CPO while a 3-dimensional flat-panel C-arm (Artis zeego; Sciemens Healthcare, Forchheim, Germany) was used to confirm the real-time 3-dimensional computed tomography (CT) images during surgery. It was possible to confirm the accurate osteotomy curve using CT images twice during surgery: at the time of the ischial osteotomy and the quadrilateral surface osteotomy. OUTCOMES: An ideal C-shaped osteotomy line was created as shown on the postoperative CT images. In addition, neither posterior column fracture nor intra-articular osteotomy was confirmed. LESSONS: The CPO using Artis zeego resulted is a satisfactory outcome, and this is the 1st report in the world to discuss the benefits of Artis zeego in pelvic osteotomy.