Introduction

Accurate implantation is important for total hip arthroplasty to achieve a maximized, stable range of motion and to reduce the risk of dislocation. We had estimated total cup and stem anteversion(AV) visually during operations without navigation system. The purpose of this study is to assess the correlation between total AV estimated visually during operation and total AV evaluated with CT and X-ray postoperatively.

The purposes of this study were to report the accuracy of stem anteversion for Exeter cemented stems with the Mako hip enhanced mode and to compare it to Accolade cementless stems.

We reviewed the data of 25 hips in 20 patients who underwent THA through the posterior approach with Exeter stems and 25 hips in 19 patients with Accolade stems were matched for age, gender, height, weight, disease, and approaches. There was no difference in the target stem anteversion (20°–30°) between the groups. Two weeks after surgery, CT images were taken to measure stem anteversion.

The difference in stem anteversion between the plan and the postoperative CT measurements was 1.2° ± 3.8° (SD) on average with cemented stems and 4.2° ± 4.2° with cementless stems, respectively (P <0.05). The difference in stem anteversion between the intraoperative measurements and the postoperative CT measurements was 0.75° ± 1.8° with Exeter stems and 2.2° ± 2.3° with Accolade stems, respectively (P <0.05).

This study demonstrated a high precision of anteversion for Exeter cemented stems with the Mako enhanced mode and its clinical accuracy was better with the cemented stems than that with the cementless stems. Although intraoperative stem anteversion measurements with the Mako system were more accurate with the cemented stems than that with the cementless stem, the difference was about 1° and the accuracy of intra-operative anteversion measurements was quite high even with the cementless stems. The smaller difference in stem anteversion between the plan and postoperative measurements with the cemented stems suggested that stem anteversion control was easier with cemented stems under the Mako enhanced mode than that with cementless stems.

Intraoperative stem anteversion measurement with Mako total hip enhanced mode was accurate and it was useful in controlling cemented stem anteversion to the target angle.

Aims

Femoral component anteversion is an important factor in the success of total hip arthroplasty (THA). This retrospective study aimed to investigate the accuracy of femoral component anteversion with the Mako THA system and software using the Exeter cemented femoral component, compared to the Accolade II cementless femoral component.

Introduction. Femoral stem anteversion after total hip arthroplasty (THA) has always been assessed using CT scan in supine position. In this study, we evaluated the anteversion of the femoral prosthesis neck in functional standing position using EOS® technology with repeatability and reproducibility of the measurements. The data obtained were compared with conventional anatomic measurements. Materials and Methods. We measured the anteversion of the femoral prosthesis neck in 45 consecutive patients who had THA performed in nine hospitals. All measurements were obtained using the EOS® imaging system with patients in comfortable standing position. The orientation of the final vector representing the femoral neck was measured on 3-dimensional reconstructions. The anatomic femoral anteversion was calculated as in a transverse plane relative to the scanner and to the plane of the reconstructed bicondylar femoral segment (femoral prosthesis neck against the femoral condyles). Functional femoral anteversion (FFA) was measured in the horizontal plane relative to the frontal plane of the patient through the center of two femoral heads. FFA embodies true anteversion of the femoral prosthesis neck relative to the pelvis, representing the combined lower extremity anteversion. Results. The average anatomic anteversion was 8.7° (−42.2 to 32.8; SD 15.2). The average functional anteversion was −0.2° (−32.7 to 30.2; SD 14.3). The paired Student t test showed a significant difference between these values (p = 0.036). Discussion. In a significant number of cases, the anatomic orientation of the prosthesis in relation to the posterior bicondylar plane does not correlate with the functional orientation of the frontal plane of the standing patient. Other factors such as tibial, femoral and acetabular anatomic features determine the overall posture of the lower limb and the functional anteversion of the femoral neck prosthesis, highlighting adaptations related to hip-knee relations. EOS® technology can assess patients in functional positions of standing, sitting, squatting or bending forward at the cost of very low exposure to irradiation. These data may be useful in future studies of the orientation of the acetabulum that explore both qualitatively and quantitatively the combined functional anatomy of hip joint and, more precisely, the phenomena of instability and subluxation