In primary total hip arthroplasty (THA) for patients with Crowe II or higher classes developmental dysplasia of the hip (DDH) or rapidly destructive coxopathy (RDC), the placement of the cup can be challenging due to superior and lateral acetabular bone defects. Traditionally, bone grafts from resected femoral heads were used to fill these defects, but bulk graft poses a risk of collapse, especially in DDH with hypoplastic femoral heads or in RDC where good quality bone is scarce. Recently, porous metal augments have shown promising outcomes in revision surgeries, yet reports on their efficacy in primary THA are limited.

This study retrospectively evaluated 27 patients (30 hips) who underwent primary THA using cementless cups and porous titanium acetabular augments for DDH or RDC, with follow-up periods ranging from 2 to 10 years (average 4.1 years). The cohort included 22 females (24 hips) and 5 males (6 hips), with an average age of 67 years at the time of surgery.

The findings at the final follow-up showed no radiographic evidence of loosening or radiolucency around the cups and augments, indicating successful biological fixation in all cases. Clinically, there was a significant improvement in the WOMAC score from an average of 39.1±14.7 preoperatively to 5.1±6.4 postoperatively. These results suggest that the use of cementless cups and porous titanium acetabular augments in primary THA for DDH and RDC can lead to high levels of clinical improvement and reliable biological fixation, indicating their potential as a viable solution for managing challenging acetabular defects in these conditions.

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.

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.

The purpose of this preliminary study was to evaluate the feasibility and accuracy of HipAlign (OrthAlign, Inc., USA) system for cup orientation in total hip arthroplasty (THA). The subjects of this study were 5 hips that underwent primary cementless THA via a posterior approach in the lateral decubitus position. Evaluation 1; after reaming acetabular bone, a trial cup was placed in the reamed acetabulum in an aimed alignment using HipAlign. Then, the trial cup alignment was measured using HipAlign and CT-based navigation system in the radiographic definition. Evaluation 2; a cementless cup was placed in the reamed acetabular in an aimed alignment using CT-based navigation and cup alignment was measured using both methods. After operation, we measured the cup alignment using postoperative CT in each patient. In the results, the average cup inclination measured with HipAlign was around 5 degrees of true cup inclination angles. The average cup anteversion with HipAlign tended to be larger than that with CT-based navigation or postoperative CT in both evaluations. That is because there is a difference in the pelvic sagittal tilt between the lateral position and supine position. In conclusion, this study suggests that guiding cup alignment with the use of HipAlign is feasible through a posterior approach and the mean cup inclination measured with HipAlign showed an acceptable level of accuracy, but the mean cup anteversion is not reliable. We need a further modification for pelvic registration to improve the accuracy of cup anteversion.

The purpose of this retrospective study was to estimate the outcome improvements after Total Hip Arthroplasty (THA) using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in patients who underwent THA with a navigation system in our institutions, and to compare them with those undergoing THA without a navigation system that had been reported in the literatures. The subjects in this study comprised 245 patients (39 males, 206 females; mean age, 59.9±12.0 years; mean BMI, 22.8±3.2 kg/m2) who underwent THA. All patients had adequate data to allow complete scoring of the WOMAC for a minimum one-year postoperative follow-up. CT-based navigation was used in all THAs. Postoperatively, no restrictions were imposed. A MEDLINE search was conducted using the search terms ‘Total hip’, ‘Quality of life (QOL)’, and ‘WOMAC’. 10 articles evaluated all WOMAC subscales one to two years after THA. The WOMAC subscale scores were compared statistically between our study and the results reported in the 10 articles using Welch's t-test. The present physical function subscale scores were the best of the 10 studies, and in 8 of the 10 studies, the differences were significant. WOMAC subscale results in our study were significantly better than those reported in most articles in which THA was performed without navigation. These results show that THA using navigation can improve patients' postoperative QOL.

The occurrence of impingement can lead to instability, accelerated wear, and unexplained pain after THA. While implant and bony impingement were widely investigated, importance of soft tissue impingement was unclear. In the THA through posterior approach, it is known that posterior soft tissue repair can decrease the risk of dislocation. However, it is not known whether anterior soft tissue impingement by anterior hip capsule will influence hip ROM. The purpose of this study is to quantitatively measure the effect of anterior capsule resection on hip ROM in vivo during posterior approach THA using hip navigation system.

From June 2011, 26 hips (25 patients) that underwent primary THA using Stryker CT-based hip navigation system were the subjects. All were female osteoarthritis patients and the average age at the operation was 59 (47–76) years. Intraoperatively, acetabular cup and femoral stem placement were performed through posterior approach under the navigation system. After reduction of the joint, we measured hip ROM using the same navigation system. We measured them before and after the resection of anterior hip capsule and compared the difference.

After the resection of anterior hip capsule, the average increases of ROM were 0.7±3.5 degrees for flexion, 2.3±2.3 degrees for extension, 1.1±2.3 degrees for abduction and 2.1±2.9 degrees for external rotation at flexion 0 degree compared with ROM before the resection. However, it significantly increased 7.5±5.1 degrees for internal rotation at flexion 90 degree (range; −3–20, paired t-test p<0.001) and 6.1±5.5 degrees for internal rotation at flexion 45 degree (range; −4–18, p<0.001).

In this study, we used navigation system for assessment of soft tissue impingement. We found that during posterior approach THA, resection of anterior hip capsule brought about significant increase of ROM, especially in the direction of flexion with internal rotation. We also found that this procedure did not change ROM of flexion, extension, abduction and external rotation. These results indicated that, during THA through posterior approach, resection of anterior hip capsule could reduce the risk of posterior instability without increasing the risk of anterior instability.