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![Cup positions relative to Lewinnek safe zone [2] in the new version group. The number of cups inside the Lewinnek safe zone was 51/55 (93%) and 56/60 (93%) in the previous version group and new version group (P = 0.592). Results of previous version group were from our previous study [24]](publication/350340071/figure/fig4/AS:1004764741529603@1616565990686/Cup-positions-relative-to-Lewinnek-safe-zone-2-in-the-new-version-group-The-number-of.png)
Cup positions relative to Lewinnek safe zone [2] in the new version group. The number of cups inside the Lewinnek safe zone was 51/55 (93%) and 56/60 (93%) in the previous version group and new version group (P = 0.592). Results of previous version group were from our previous study [24]
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![Cup positions relative to Lewinnek safe zone [2] in the new version...](publication/350340071/figure/fig4/AS:1004764741529603@1616565990686/Cup-positions-relative-to-Lewinnek-safe-zone-2-in-the-new-version-group-The-number-of_Q320.jpg)
Background
Complications after total hip arthroplasty (THA) are frequently the consequence of malpositioned components or leg length discrepancy after surgery. Recently, a new version of a portable, accelerometer-based hip navigation system (New HipAlign) was made available with a change in the method of measuring cup abduction and the addition of...
Citations
... Navigation systems that can place the acetabular cup at the target angle for individual patients will play an even greater role. Among them, portable navigation systems that not only enable accurate acetabular cup placement but are also inexpensive and portable may help promote widespread use [4][5][6]. ...
... Image-based and robotic-assisted navigation systems, which use preoperative CT images to create a patient-specific 3D pelvic coordinate system for intraoperative guidance, have reported absolute errors in both inclination and anteversion angles of 1° to 4° [8,9,24]. The high cost of large image-based and robot-assisted navigation systems is a concern in terms of their widespread use [4][5][6]. In the were 1.7° in inclination and 2.5° in anteversion, which was statistically significant, but the values themselves were relatively small. ...
Introduction
The accuracy of acetabular cup placement using conventional portable imageless navigation systems in total hip arthroplasty (THA) in the lateral decubitus position remains challenging. Several novel portable imageless navigation systems have been developed recently to improve cup placement accuracy in THA. This study compared the accuracy of acetabular cup placement using a conventional accelerometer-based portable navigation (c-APN) system and a novel accelerometer-based portable navigation (n-APN) system during THA in the lateral decubitus position.
Materials and methods
This retrospective cohort study compared 45 THAs using the c-APN and 45 THAs using the n-APN system. The primary outcomes were the absolute errors between the intraoperative and postoperative values of acetabular cup radiographic inclination and anteversion angles and the percentage of cases with absolute errors within 5°. Intraoperative values were shown on navigation systems, and postoperative measurements were conducted using computed tomography images.
Results
The median absolute errors of the cup inclination angles were significantly smaller in the n-APN group than in the c-APN group (3.9° [interquartile range 2.2°–6.0°] versus 2.2° [interquartile range 1.0°–3.3°]; P = 0.002). Additionally, the median absolute errors of the cup anteversion angles were significantly smaller in the n-APN group than in the c-APN group (4.4° [interquartile range 2.4°–6.5°] versus 1.9° [interquartile range 0.8°–2.7°]; P < 0.001). Significant differences were observed in the percentage of cases with absolute errors within 5° of inclination (c-APN group 67% versus n-APN group 84%; P = 0.049) and anteversion angles (c-APN group 62% versus n-APN group 91%; P = 0.001).
Conclusions
The n-APN system improved the accuracy of the cup placement compared to the c-APN system for THA in the lateral decubitus position.
... Previous studies revealed that fPNS achieves sufficient accuracy for THA conducted in the supine position [6][7][8][9][10][11]. However, fPNS do not provide sufficient accuracy for THA conducted in the lateral decubitus position as the patient's body axis has to be registered after position placement [12][13][14][15][16]. Recently, second-generation PNS (sPNS) have been developed using augmented reality (AR) based on smartphones (AR-Hip; Zimmer Biomet Japan, Tokyo, Japan) and handheld infrared stereo cameras based on accelerometers (Naviswiss; Naviswiss AG, Brugg, Switzerland). ...
Background
The use of portable navigation systems (PNS) in total hip arthroplasty (THA) has become increasingly prevalent, with second-generation PNS (sPNS) demonstrating superior accuracy in the lateral decubitus position compared to first-generation PNS. However, few studies have compared different types of sPNS. This study retrospectively compares the accuracy and clinical outcomes of two different types of sPNS instruments in patients undergoing THA.
Methods
A total of 158 eligible patients who underwent THA at a single institution between 2019 and 2022 were enrolled in the study, including 89 who used an accelerometer-based PNS with handheld infrared stereo cameras in the Naviswiss group (group N) and 69 who used an augmented reality (AR)-based PNS in the AR-Hip group (group A). Accuracy error, navigation error, clinical outcomes, and preparation time were compared between the two groups.
Results
Accuracy errors for Inclination were comparable between group N (3.5° ± 3.0°) and group A (3.5° ± 3.1°) (p = 0.92). Accuracy errors for anteversion were comparable between group N (4.1° ± 3.1°) and group A (4.5° ± 4.0°) (p = 0.57). The navigation errors for inclination (group N: 2.9° ± 2.7°, group A: 3.0° ± 3.2°) and anteversion (group N: 4.3° ± 3.5°, group A: 4.3° ± 4.1°) were comparable between the groups (p = 0.86 and 0.94, respectively). The preparation time was shorter in group A than in group N (p = 0.036). There were no significant differences in operative time (p = 0.255), intraoperative blood loss (p = 0.387), or complications (p = 0.248) between the two groups.
Conclusion
An Accelerometer-based PNS using handheld infrared stereo cameras and AR-based PNS provide similar accuracy during THA in the lateral decubitus position, with a mean error of 3°–4° for both inclination and anteversion, though the AR-based PNS required a shorter preparation time.
... All patients underwent THA using INS (Navbit Sprint; Navbit Pty Ltd., Sydney, Australia) for cup placement. The surgical team had used several other portable hip navigation systems for more than four hundred THA prior to the present study [21][22][23] . INS contains inertial sensors, including accelerometers and gyroscopes, and consists of a disposable navigation unit (Navigation Device), Device Mount, bone pins, and Impactor Fitting (Fig. 1). ...
... On axial CT images obtained through the central position of the cup, cup anteversion was measured perpendicular to a line drawn across the ischial spines. Digital measurements of postoperative cup angles (ViewR; YOKOGAWA, Japan) were performed by one observer, as previously reported [21][22][23] . Data obtained for cup anteversion were converted to radiographic definitions and then analyzed 28 . ...
Accurate cup placement is critical to ensure satisfactory outcomes after total hip arthroplasty. Portable hip navigation systems are novel intraoperative guidance tools that achieve accurate cup placement in the supine position; however, accuracy in the lateral decubitus position is under debate. A new inertial portable navigation system has recently become available. The present study investigated the accuracy of measurements of the cup position in 54 patients in the lateral decubitus position using this system and compared it with that by a goniometer. After cup placement, cup abduction and anteversion were measured using the system and by the goniometer, and were then compared with postoperatively measured angles. Absolute measurement errors with the system were 2.8° ± 2.6° for cup abduction and 3.9° ± 2.9° for anteversion. The system achieved 98 and 96% measurement accuracies within 10° for cup abduction and anteversion, respectively. The system was more accurate than the goniometer for cup anteversion (p < 0.001), but not for abduction (p = 0.537). The system uses a new registration method of the pelvic reference plane and corrects intraoperative pelvic motion errors, which may affect measurement accuracy. In the present study, reliable and reproducible intraoperative measurements of the cup position were obtained using the inertial portable navigation system.
... However, several reasons, such as high costs, complicated procedures, and the need for space for a large console, have prevented their widespread use in actual clinical practice. Portable navigation systems have been expected to offer low costs, ease of use, and portability, without requiring a large space, regardless of the surgeon's experience and hospital size [8][9][10]. ...
... The accuracy of the cup placement, especially in terms of cup anteversion, in THA in the lateral decubitus position using the previous accelerometer-based portable navigation (APN) systems was worse than that in the supine position [6][7][8][9][10][11][12][13][14][15][16]. Many studies demonstrated that the accuracy of cup placement in THA in the supine position using the previous APN system was better than that using a conventional alignment guide, a manual goniometer, or fluoroscopy [9,12,[14][15][16]. ...
... and a median body mass index (BMI) of 23.3 kg/m 2 (IQR 21.0-26.8). The median follow-up period was 12 months (IQR [6][7][8][9][10][11][12][13][14][15][16][17][18]. There were 45 hips in the supine group and 44 in the lateral group (Fig. 1). ...
Introduction
No studies have compared the accuracy of acetabular cup placement in total hip arthroplasty (THA) in the supine and lateral decubitus positions using the same portable navigation system. Thus, this study aimed to compare the accuracy of acetabular cup placement using a new accelerometer-based portable navigation system combined with an infrared stereo camera and inertial measurement unit between the supine and lateral decubitus positions.
Materials and methods
This retrospective study compared 45 THAs performed in the supine position (supine group) and 44 THAs performed in the lateral decubitus position (lateral group) using the same portable navigation system. The primary outcome was the absolute errors of cup placement angles, defined as the absolute values of the differences between cup radiographic inclination and anteversion angles displayed on the navigation system and those measured on postoperative computed tomography images.
Results
No significant difference in the median absolute error of the cup inclination angle (supine group 1.7° [interquartile range 0.8°–3.1°] vs. lateral group 2.1° [interquartile range 1.0°–3.7°]; p = 0.07) was found between the two groups. Similarly, no significant difference in the median absolute error of the anteversion angle (supine group 1.9° [interquartile range 0.8°–3.4°] vs. lateral group 2.1° [interquartile range 0.9°–3.1°]; p = 0.42) was found.
Conclusion
This new accelerometer-based portable navigation system may provide high accuracy of the cup placement in THA in the lateral decubitus and supine positions.
... Therefore, cup placement accuracy was expected to improve through portable navigation system use. Several reports have demonstrated the accuracy of cup placement using portable navigation system [14][15][16][27][28][29]. Cross et al. reported that the absolute values of inclination errors were 4.2° ± 3.2° and the anteversion errors were 4.0° ± 4.0° using 3-D mini-optical navigation in the lateral position [29]. ...
Introduction
This study compared the accuracy of three dimensional (3D) mini-optical navigation and accelerometer-based portable navigation systems for cup positioning during a total hip arthroplasty (THA) in the supine position.
Materials and methods
This retrospective cohort study assessed data for 77 hips using 3D mini-optical navigation (n = 37) and accelerometer-based portable navigation (n = 40). The patients underwent THA through the mini-anterolateral approach in the supine position using a portable navigation system. We assessed the preoperative target angles, recorded intraoperative cup angles, postoperative CT imaging angles, cup angle measurement errors, and other clinical parameters.
Results
The mean absolute differences in radiographic inclination were similar between 3D mini-optical navigation and accelerometer-based portable navigation systems during THA in the supine position (2.8° ± 1.7° vs 2.8° ± 1.9°, p = 0.637). The mean absolute differences in radiographic anteversion were also similar (2.6° ± 2.3° vs 2.5° ± 1.9°, p = 0.737). Cup malalignment (absolute difference of inclination or anteversion between postoperative CT and preoperative target angle of > 5°) was significantly associated with body mass index (BMI) in accelerometer-based portable navigation but not in 3D mini-optical navigation.
Conclusions
This is the first study to compare the accuracy of cup positioning between 3D mini-optical and accelerometer-based navigations in THA in the supine position. Both portable navigation systems accurately identified the orientation of cup placement. The accuracy of 3D mini-optical navigation is not affected by high BMI and may be preferred over other options in such patients.
... The costs are much lower for portable navigation systems than for large console navigation systems. An accelerometer-based portable navigation system (HipAlign; OrthAlign, Aliso Viejo, CA) has been used in THA, comprising accelerometers, gyroscopes, and inertial detectors to communicate between a reference sensor and the display unit [6][7][8][9][10][11][12][13]. Several studies have reported that HipAlign has significantly improved the accuracy of cup inclination and anteversion [6][7][8][9][10][11][12][13]. ...
... An accelerometer-based portable navigation system (HipAlign; OrthAlign, Aliso Viejo, CA) has been used in THA, comprising accelerometers, gyroscopes, and inertial detectors to communicate between a reference sensor and the display unit [6][7][8][9][10][11][12][13]. Several studies have reported that HipAlign has significantly improved the accuracy of cup inclination and anteversion [6][7][8][9][10][11][12][13]. ...
... The absolute value of navigation error in inclination was reported as 3.2° and navigation error in anteversion was 6.0° in the lateral decubitus position [13]. The absolute deviation of the postoperative measured angle from the target position was 3.7°in inclination, and the values in anteversion were ranged from 5.9° to 6.0° [11,12]. HipAlign of the supine position seemed to be better for anteversion accuracy compared with that of the lateral decubitus position. ...
Background
This study aimed to determine the accuracy of acetabular cup insertion using a novel accelerometer-based navigation system in total hip arthroplasty (THA).
Methods
A single-surgeon study was conducted in which 62 prospective patients with navigation and 42 retrospective patients without navigation in a supine position were compared. Absolute values for errors of radiographic inclination and anteversion were calculated. Navigation error was also calculated. Factors that affected absolute value of navigation error in cup alignment were determined.
Results
In the navigation group, mean absolute errors for radiographic inclination and anteversion were 4.1° and 4.3°, respectively. In the control group, mean absolute errors were 6.6° in inclination ( p < 0.01) and 5.9° in anteversion ( p = 0.04). Mean absolute values of navigation error were 2.8° in inclination and 2.8°in anteversion. Factors affecting navigation errors were not found.
Conclusion
This novel accelerometer-based navigation system significantly increased the accuracy of cup placement during THA in the supine position.
Navigation-assisted surgical procedures in orthopedics and trauma surgery have become increasingly widespread over the last 20 years. In addition to applications in spinal surgery, they are primarily available for knee and hip endoprosthetics. On the one hand, computer-assisted procedures have been increasingly expanded with robotic assistance systems in recent years, and on the other hand, so-called handheld navigation systems have been developed, which enable specialized use directly in the operating field at lower acquisition costs. The aim of this overview is to describe current handheld systems and to present the respective technical principles and the available scientific results. Three handheld systems for TKA use, two for THA use and one system to support pedicle screw placement on the spine are presented.
Background
The aim of this study was examining the accuracy of accelerometer-based portable navigation systems (HipAlign) when measuring leg length changes using two-dimensional (2D) and three-dimensional (3D) methods.
Methods
Inclusion criteria were patients ≥ 20 years old with symptomatic hip disease who underwent primary total hip arthroplasty (THA) in the supine position using HipAlign between June 2019 and April 2020. The exclusion criteria were patients who underwent THA via a posterior approach. We examined correlations between the leg length change measurement with HipAlign and either 2D or 3D measurement. We performed a multivariate analysis to determine which factors may have influenced the absolute error results.
Results
This study included 34 patients. The absolute error in leg length change between the HipAlign and 3D measurement (4.0 mm) was greater than the HipAlign and 2D measurement (1.7 mm). There were positive correlations between leg length change with HipAlign and 2D and 3D measurements. Male patients had larger errors with 2D measurement. No significant factors were identified for 3D measurement.
Conclusion
HipAlign provided acceptable measurement accuracy for leg length changes.
Aiming for a combined cup and stem anteversion within a target range is one way to assess appropriate prosthetic component orientation and restoration of functional range of motion. We describe a surgical technique that allows the surgeon to assess the combined anteversion using a handheld accelerometer-based navigation system for total hip arthroplasty through a posterior approach. The femur is prepared first, at which time the femoral version is estimated by the surgeon. The acetabular component is then positioned using the navigation system to estimate anteversion, with the goal of providing a combined version of 37° ± 7°. The described technique allows surgeons to achieve the desired intraoperative combined anteversion.
Level of evidence
IV (technical note).
Background:
Portable hip navigation systems have been developed to combine the accuracy of cup positioning by large console navigation systems with the ease of use and convenience of conventional surgical techniques. Although a novel augmented reality-based portable hip navigation system using a smartphone (AR navigation) has become available recently, no studies, to our knowledge, have compared commercially available AR navigation with the conventional technique. Additionally, no studies, except for those from designer-surgeon series, have demonstrated the results of AR navigation.
Questions/purposes:
(1) Does intraoperative use of commercially available AR navigation improve cup positioning compared with the conventional technique? (2) Are operative factors, clinical scores, and postoperative course different between the two groups?
Methods:
In this randomized trial, 72 patients undergoing THA were randomly assigned to undergo either commercially available AR navigation or a conventional technique for cup placement. All patients received the same cementless acetabular cups through a posterior approach in the lateral decubitus position. The primary outcome of the present study was cup positioning, including the absolute differences between the intended target and angle achieved, as well as the number of cups inside the Lewinnek safe zone. Our target cup position was 40° abduction and 20° anteversion. Secondary outcomes were operative factors, between-group difference in improvement in the Hip Disability and Osteoarthritis Outcome Score (HOOS), and the postoperative course, including the operative time (between the start of the surgical approach and skin closure), procedure time (between the first incision and skin closure, including the time to insert pins, registration, and transfer and redrape patients in the navigation group), time taken to insert pins and complete registration in the navigation group, intraoperative and postoperative complications, and reoperations. The minimum follow-up period was 6 months, because data regarding the primary outcome-cup positioning-were collected within 1 week after surgery. The between-group difference in improvement in HOOS, which was the secondary outcome, was much lower than the minimum clinically important difference for the HOOS. No patients in either group were lost to follow-up, and there was no crossover (the randomized treatment was performed in all patients, so there was no difference between an intention-to-treat and a per-protocol analysis).
Results:
The use of the commercially available AR navigation slightly improved cup positioning compared with the conventional technique in terms of the absolute difference between the desired and achieved amounts of cup abduction and anteversion (which we defined as "absolute differences"; median 1° [IQR 0° to 4.0°] versus median 5° [IQR 3.0° to 7.5°], difference of medians 4°; p < 0.001 and median 2° [IQR 1.9° to 3.7°] versus median 5° [IQR 3.2° to 9.7°], difference of medians 2°; p = 0.001). A higher proportion of cups were placed inside the Lewinnek safe zone in the navigation group than in the control group (94% [34 of 36] compared with 64% [23 of 36]; p < 0.001). Median operative times were not different between the two groups (58 minutes [IQR 49 to 72 minutes] versus 57 minutes [IQR 49 to 69 minutes], difference of medians 1 minute; p = 0.99). The median procedure time was longer in the navigation group (95 minutes [IQR 84 to 109 minutes] versus 57 minutes [IQR 49 to 69 minutes], difference of medians 38 minutes; p < 0.001). There were no differences between the two groups in improvement in HOOS (27 ± 17 versus 28 ± 19, mean difference -1 [95% CI -9.5 to 7.4]; p = 0.81). In the navigation group, no complications occurred in the pin sites; however, one anterior dislocation occurred. In the conventional group, one hip underwent reoperation because of a deep infection.
Conclusion:
Although the use of commercially available AR navigation improved cup positioning in THA, the improvement in clinical scores and postoperative complication rates were not different between the two groups, and the overall magnitude of the difference in accuracy was small. Future studies will need to determine whether the improvement in the percentage of hips inside the Lewinnek safe zone results in differences in late dislocation or polyethylene wear, and whether such benefits-if any-justify the added costs and surgical time. Until or unless more compelling evidence in favor of the new system emerges, we recommend against widespread use of the system in clinical practice.
Level of evidence:
Level Ⅱ, therapeutic study.
