Accuracy of augmented reality with computed tomography-based navigation in total hip arthroplasty

Use of augmented reality surgical navigation reduces intraoperative fluoroscopic imaging in anterior total hip arthroplasty with equivalent accuracy for component positioning

Background

Computer-assisted surgical navigation was designed to reduce the rates of acetabular component malpositioning, a common cause for revision following primary total hip arthroplasty (THA). We compared intraoperative measures such as radiation exposure, radiographic acetabular cup placement, and outcomes of patients who underwent a THA using computer-assisted surgical navigation with augmented reality (AR) compared to those who underwent traditional manual THA with fluoroscopic assistance (FA).

Methods

We retrospectively reviewed 115 hips who underwent primary direct anterior THAs using the intraoperative AR surgical navigation system between 3/30/2021 and 12/30/2022. These were compared to a matched cohort of 115 primary THAs performed with FA through a direct anterior approach during the same time period. Patients were matched based on age, gender, American Society of Anesthesiologists score (ASA), and BMI. Goal inclination and anteversion were set to 42° (°) and 22°, respectively.

Results

THA with AR patients had decreased intraoperative radiation exposure (mean 2.0 versus 3.2 mGy, p < 0.001) and radiation time (mean 0.2 versus 0.4 min, p < 0.001). Deviation from the preoperative plan was similar between AR and FA for both radiographic inclination and anteversion. There was no difference in the operative time, estimated blood loss, or reoperations, all of which were for infection (1.7 versus 0.0 %, p = 0.5).

Conclusion

AR surgical navigation in primary THA has similar radiographic, operative and clinical results as THA with intraoperative FA. However, AR surgical navigation is associated with decreased intraoperative fluoroscopic radiation and time. Further research is needed to evaluate accuracy of acetabular component positioning and complications.

A novel patient-specific free-hand method using fluoroscopic templating for accurate cup placement in supine position total hip arthroplasty

INTRODUCTION

We developed a fluoroscopic templating technique for accurate cup placement based on the acetabular morphology of individual patients during supine position total hip arthroplasty (THA) to reduce the risk of dislocation. This study aimed to evaluate cup positioning accuracy with and without this technique.

MATERIALS AND METHODS

We evaluated 75 consecutive hips of 70 patients undergoing cementless anterolateral supine THA. The target angle for radiographic inclination (RI) and radiographic anteversion (RA) were set using a computed tomography (CT)-based functional pelvic plane. In 25 hips, we implanted the cup using a mechanical alignment guide (C-group). A fluoroscopic templating technique was used in 50 hips (FT-group), and a reference line based on the acetabular morphology was preoperatively set in each patient for the RI guide. A reference diagram was made for the RA guide. Postoperative CT scans were used to compare cup positioning accuracy between groups.

RESULTS

The absolute values of the error from the target angle were 3.2 ± 2.0° (RI) and 6.5 ± 3.8° (RA) in the C-group, and 1.5 ± 1.2° (RI) and 2.6 ± 1.9° (RA) in the FT-group. The errors of both RI and RA were significantly smaller in the FT-group than in the C-group. The rates of cases within ± 5° of the target angles for both RI and RA were 48% (C-group) and 92% (FT-group). The mean fluoroscopic times were 32.2 s (C-group) and 17.4 s (FT-group).

CONCLUSION

Our simple patient-specific technique achieved accurate cup positioning; this may reduce the risk of dislocation.

Accuracy of Acetabular Component Positioning Using a Mixed Reality-Guided Navigation System During Total Hip Arthroplasty

Background

Surgeons increasingly recognize the importance of patient-specific considerations in determining ideal cup alignments. In addition, various surgical navigation systems have been reported to improve cup placement accuracy during total hip arthroplasty (THA). Recently, a novel computed tomography (CT)-based planning and mixed-reality (MR) guidance system was developed to enable patient-specific 3-dimensional planning of the ideal cup position and further improve intraoperative achievement of the planned orientation.

Methods

This is retrospective, observational study of 40 patients (40 hips) who underwent MR-guided THA. Patient-specific CT-based surgical planning with definition of target operative anteversion and inclination of the acetabular cup in relation to the anterior pelvic plane was performed. 3D holograms of the cup and cup impactor in the selected target position were created and exported. Intraoperatively, automatic holographic registration was performed using a smart tool-based linked-paired-point matching method. Patient-specific content was displayed on a head-mounted display, and the acetabular component was inserted by matching the spatial position of the cup impactor with the hologram of the cup impactor in the target position. Postoperatively, patients underwent biplane simultaneous imaging for measurement of achieved cup alignment using a validated measurement method.

Results

Mean planned operative anteversion and inclination angles were 28.4° ± 1.6° (95% confidence interval [CI], 27.9°-28.8°) and 39.9° ± 0.3° (95% CI, 39.8°-40.0°), respectively. The mean absolute target error between preoperative target operative anteversion and the achieved operative anteversion was 0.7° ± 1.1° (95% CI, 0.3°-1.0°; range, 0°-4°). The mean absolute target error between preoperative target operative inclination and the achieved operative inclination was 1.1° ± 1.2° (95% CI, 0.7°-1.4°; range, 0°-4°).

Conclusion

Acetabular component positioning using a mixed reality guidance system during THA was highly accurate and well within the accuracy reported for other navigation systems.

Level of Evidence

Level III. See Instructions for Authors for a complete description of levels of evidence.

Accuracy of leg length changes in total hip arthroplasty using a computed tomography-based augmented reality navigation system

INTRODUCTION

Leg length is an important consideration in total hip arthroplasty (THA) as leg length discrepancies (LLD) after THA cause poor outcomes and medical litigation. This study aimed to investigate the accuracy of computed tomography (CT)-based navigation with augmented reality (AR) technology for measuring intra-operative leg length change using anteroposterior radiography (two-dimensional, 2D) and CT (three-dimensional, 3D).

MATERIALS AND METHODS

This study included 71 patients (75 hips) who underwent primary cementless THA in the supine position between June 2022 and November 2023 using the HoloNavi One. To assess the accuracy of the HoloNavi One based on 2D and 3D measurements, the absolute error between the intra-operative leg length change and the 2D and 3D measurements was evaluated, and the correlations were investigated. Additionally, factors affecting the absolute error were examined using multivariate analysis.

RESULTS

The mean intra-operative leg length change when using the HoloNavi One was 6.5 ± 5.0 mm, while the mean leg length change on the 2D and 3D measurements were 5.9 ± 4.8 mm and 4.6 ± 5.7 mm, respectively. The mean absolute errors were 2.3 ± 2.7 mm between the HoloNavi One and 2D measurements, and 3.8 ± 3.3 mm between HoloNavi One and 3D measurements. The absolute errors in leg length changes for the 3D measurements were greater than those for the 2D measurements (p < 0.01). Positive correlations of leg length changes were found between the HoloNavi One and the 2D and 3D measurements. In the multiple regression analysis, no significant factors affecting the absolute error were identified in either the 2D or 3D measurements.

CONCLUSIONS

CT-based navigation with AR technology in the supine position provided acceptable accuracy for leg length change measurements.

Accuracy of cup placement and pelvic motion in total hip arthroplasty in the lateral decubitus position using a new computed tomography-based navigation system with augmented reality technology

INTRODUCTION

This study aimed to investigate the accuracy of cup position and assess the changes in pelvic tilt during primary total hip arthroplasty (THA) in the lateral decubitus position using a new computed tomography (CT)-based navigation system with augmented reality (AR) technology.

MATERIALS AND METHODS

There were 37 cementless THAs performed using a CT-based navigation system with AR technology in the lateral decubitus position and 63 cementless THAs performed using manual implant techniques in the lateral decubitus position in this retrospective study. Postoperative cup radiographic inclination and anteversion were measured using postoperative CT, and the proportion of hips within Lewinnek's safe zone was analyzed and compared between the two groups. The mean absolute values of navigation error were assessed. Intraoperative pelvic tilt angles were also recorded using navigation system.

RESULTS

The percentage of cups inside Lewinnek's safe zone was 100% in the navigation group and 35% in the control group (p < 0.001). The mean absolute values of navigation error in inclination and anteversion were 2.9° ± 2.1° and 3.3° ± 2.4°, respectively. The mean abduction angle of the pelvis was 5.1° ± 4.8° after placing the patients in the lateral decubitus position and 4.1° ± 6.0° after cup placement. The mean posterior tilt angle was 6.8° ± 5.1° after placing the patients in the lateral decubitus position and 9.3° ± 5.9° after cup placement. The mean internal rotation angle was 14.8° ± 7.4° after cup placement. There were no correlations between the navigation error in inclination or anteversion and the absolute values of changes of the pelvic tilt angle at any phase.

CONCLUSIONS

Although progressive pelvic motion occurred in THA in the lateral decubitus position, especially during cup placement, the CT-based navigation system with AR technology improved cup placement accuracy.

Comparison between accuracy of augmented reality computed tomography-based and portable augmented reality-based navigation systems for cup insertion in total hip arthroplasty

Augmented reality (AR) has been used for navigation during total hip arthroplasty (THA). AR computed tomography (CT)-based navigation systems and AR-based portable navigation systems that use smartphones can also be used. This study compared the accuracy of cup insertion during THA using AR-CT-based and portable AR-based navigation systems. Patients with symptomatic hip disease who underwent primary THA in the supine position using both AR CT-based and portable AR-based navigation systems simultaneously between October 2021 and July 2023 were included. The primary outcome of this study was the absolute difference between cup angles in the intraoperative navigation record and those measured on postoperative CT. The secondary outcome was to determine the factors affecting the absolute value of the navigation error in radiographic inclination (RI) and radiographic anteversion (RA) of the cup, including sex, age, body mass index, left or right side, approach, and preoperative pelvic tilt. This study included 94 consecutive patients. There were 11 men and 83 women, with a mean age of 68 years. The mean absolute errors of RI were 2.7° ± 2.0° in the AR CT-based and 3.3° ± 2.4° in the portable AR-based navigation system. The mean absolute errors of RA were 2.5° ± 2.1° in the AR CT-based navigation system and 2.3° ± 2.2° in the portable AR-based navigation system. No significant differences were observed in RI or RA of the cup between the two navigation systems (RI: p = 0.706; RA: p = 0.329). No significant factors affected the absolute value of the navigation errors in RI and RA. In conclusion, there were no differences in the accuracy of cup insertion between the AR CT-based and portable AR-based navigation systems.