Comparison of a mechanical acetabular alignment guide with computer placement of the socket

The efficiency of patient-specific instrumentation and technological assistance in cementless total hip arthroplasty via the direct anterior approach

BACKGROUND

Patient-specific instrumentation for total hip arthroplasty (PSI-THA) is an emerging technology that improves the accuracy of femoral neck osteotomy and implant positioning. Unlike conventional 2D radiograph-based planning, PSI-THA leverages 3D CT reconstructions for personalized, technology-assisted positioning. This study sought to assess the intraoperative efficiency of PSI-THA in terms of surgery duration and blood loss by comparing PSI incorporating image-based guides and 3D planning with conventional surgery and 2D planning for cementless THA performed via the direct anterior approach (DAA).

METHODS

Two consecutive cohorts of 100 patients each were retrospectively analysed. All patients underwent cementless THA with a straight quadrangular stem and a ceramic-on-ceramic head and liners. Two-dimensional templating was performed for the first cohort, whereas a 3D template with CT-based PSI for femoral neck osteotomy and acetabular cup positioning was performed for the second cohort. A laser guidance system was employed to increase implant placement accuracy. Operating time and intraoperative blood loss were compared between the groups.

RESULTS

The demographic characteristics of the two groups were comparable. The average operating time was 45.7 min (SD: 16.11) in the conventional group and 31.9 min (SD: 9.92) in the PSI group (p < 0.001). Blood loss was also significantly lower in the PSI group (319 ml) than in the conventional group (407 ml; p < 0.017).

CONCLUSIONS

Compared with conventional planning, PSI with 3D planning and technological assistance significantly reduced the operating time by an average of over 10 min as well as the amount of blood loss. The improved planning and execution accuracy of PSI minimizes the need for intraoperative adjustments, improves confidence in implant positioning, and reduces the need for compromises and the identification of multiple landmarks, underscoring the value of this planning technology in DAA THA.

CLINICAL TRIAL NUMBER

Not applicable.

Reducing variability in apparent operative inclination (AOI) during total hip arthroplasty: comparing the ball in cage mechanical alignment device to a digital inclinometer

INTRODUCTION

When operating in lateral decubitus apparent operative inclination (AOI) is the angle between the handle of the acetabular cup introducer and the theatre floor. A digital inclinometer has demonstrated optimal control of AOI. This study aims to compare the deviation from a target AOI with a novel autoclavable ball-in-cage mechanical alignment guide (MAG) as compared to a digital inclinometer.

METHODS

90 primary total hip arthroplasty cases performed in lateral decubitus using a posterior approach were included. The ball-in-cage mechanical alignment guide on a standard Pinnacle cup introducer handle was used to achieve the target AOI of 35° ± 2.5°. Final AOI was measured with a digital inclinometer. These readings were compared to a published historical series of 90 patients using a digital inclinometer.

RESULTS

The ball-in-cage MAG mean inclination was 35.0° (range 32.5-37.4°), with 100% falling within target. This compared to a mean inclination of 34.0° (range 27.5-37.5°), with the digital inclinometer where 87.8% fell within target. However, the range of postoperative radiographic inclination for the ball-in-cage MAG was 23.4-53.9° with 31.1% being outside a ±5° target.

CONCLUSIONS

These results indicate that this simple autoclavable ball-in-cage MAG consistently achieves an intraoperative AOI within target range. In isolation this does not guarantee a postoperative radiographic inclination within target range.

How Much Does a Computed Tomography-Based Mixed-Reality Navigation System Change Freehand Acetabular Component Position?

Background

This study evaluates how a computed tomography-based mixed-reality (MR) navigation system impacts acetabular component orientation compared to freehand positioning in total hip arthroplasty.

Methods

A series of 79 patients who underwent total hip arthroplasty utilizing a computed tomography-based MR navigation system were reviewed. The surgeon initially placed the acetabular cup freehand, attempting to achieve the preoperative plan, and this initial intraoperative orientation was recorded. The cup was then adjusted to the planned position. The difference between freehand and planned tilt-adjusted operative anteversion (OA) and inclination (OI) determined the navigation tool's impact.

Results

The mean preoperative planned OA was 30.1 ± 2.0 (range: 25, 35) degrees, and the mean freehand intraoperative OA was 30.2 ± 9.1 (range: 4, 57) degrees (P = .885), requiring a mean adjustment of 6.8 ± 5.1 (range: 0, 23) degrees. Freehand OA was corrected at least 5 degrees in 54.4% (43/79) of cases. The mean preoperative planned OI was 40.8 ± 0.6 (range: 39, 42) degrees, and the mean freehand intraoperative OI was 37.8 ± 6.6 (range: 18, 53) degrees (P < .001), requiring a mean adjustment of 5.7 ± 4.5 (range: 0, 22) degrees to achieve. Freehand OI was corrected at least 5 degrees in 43.0% (34/79) of cases.

Conclusions

Freehand acetabular component positioning in the lateral position is variable when attempting to execute patient-specific numerical cup orientation targets. Use of this navigation tool led the surgeon to correct more than 5 degrees in both OA and OI in roughly half of the hips.

Accuracy of Implant Positioning in Total Hip Arthroplasty via a Supine Direct Anterior Approach Using Fluoroscopy

Background: Adequate implantation is important to avoid complications following total hip arthroplasty (THA). This study aimed to evaluate the accuracy and precision of implant placement in the direct anterior approach (DAA) using fluoroscopy in comparison with the anterolateral approach in lateral decubitus position (OCM) using a single implant. Methods: We retrospectively compared propensity score-matched THAs in DAA with fluoroscopy and in OCM. The achievement ratio of the Lewinnek cup safe zone, absolute difference in alignment, and positioning from preoperative planning was evaluated and compared between each approach. Results: 33 patients in both groups were eligible for this study. Significantly more cups were inside the safe zone in the DAA group than in the OCM group (33/33 vs. 25/33, p=0.0048). No significant differences were found between the DAA group and OCM group regarding the discrepancy from the target cup inclination, anteversion, and three-dimensional positioning. No significant difference was noted in stem alignment; however, the equality of coronal alignment variances was smaller in the DAA group (p=0.0047). No significant differences were found in the clinical score and complication rate. Conclusion: The DAA using fluoroscopy may provide more accuracy for cup placement and precision for stem placement than OCM.

Knee-Sparing Resection and Reconstruction Surgery for Bone Sarcoma Using 3D-Surgical Approach: Average of 5-Year Follow-Up

Background and Objectives: To date, the gold standard of care for bone sarcomas is limb salvage surgical resection. In cases where the tumor arises in the distal femur or proximal tibia near the joint line, knee-sacrificing surgery is typically performed, followed by reconstruction with oncological megaprostheses. This study aims to evaluate the effectiveness of a precise 3D-based surgical approach for knee-sparing tumor resections, assessing its feasibility and its impact on surgical, oncological, and functional outcomes. Materials and Methods: This single-center retrospective study presents the surgical and oncological outcomes of knee-sparing surgeries following bone sarcoma resections. All patients underwent either intercalary or geographic resection, and reconstruction was tailored to each patient, using either an allograft or a titanium alloy Ti64 implant, depending on the specific requirements of the case. Results: A total of 23 patients (average age 21.04 years, 14 males) were included, with an average postoperative follow-up of 58 months (range: 12-102 months). Clear surgical margins were achieved in all patients, with 16 patients (69.5%) showing wide negative margins (R0) and the rest showing close negative margins (R1). Resections were primarily intercalary (17 patients, 73.9%), with 6 patients (26.1%) undergoing geographic resections. Reconstruction methods included allografts (9 patients, 39.3%), vascularized fibula and allograft (8 patients, 34.7%), and printed Ti64 cage reconstructions (6 patients, 26.0%). At the last follow-up, 19 patients (82.6%) were disease-free, 3 patients (13.4%) were alive with evidence of disease, and 1 patient (4%) was dead of disease. Complications included four cases of non-union that required revision surgery, as well as two local recurrences, which necessitated revision surgery to a modular endoprosthesis and above-knee amputation. The average MSTS at the final follow-up was 23.16 ± 5.91. Conclusions: The use of 3D-printed PSIs for knee-sparing bone tumor resections has emerged as the gold standard, enhancing both surgical and oncological outcomes. A future challenge lies in improving reconstruction techniques, shifting from traditional allografts to customized Ti64 printed lattice implants. As personalized healthcare and additive manufacturing continue to advance, the future of orthopedic oncology will likely see more precise, durable, and biologically integrated implants, further improving patient outcomes.

Evaluating the Accuracy of a Computed Tomography-Based Mixed-Reality Navigation Tool for Acetabular Component Positioning in Total Hip Arthroplasty

BACKGROUND

Robotics and navigation systems have improved the accuracy and precision of acetabular component placement in total hip arthroplasty (THA). The purpose of this study was to determine if the intraoperative use of a novel mixed-reality (MR) navigation system resulted in accurate acetabular component placement with minimal outliers.

METHODS

A series of 79 patients who underwent THA performed by a single surgeon using a novel MR navigation system were retrospectively reviewed. The preoperative planned acetabular component operative inclination (OI) and tilt-adjusted operative anteversion (OA) were collected for each case. At the six-week follow-up, each patient underwent three-dimensional EOS imaging, which was used to measure the acetabular component placement via validated measuring software. Patients who had bilateral THAs or three-dimensional images that did not have critical bony landmarks visible for measurement were excluded from the study. Absolute error was calculated for both inclination and anteversion. Outliers were defined as any cup position that was outside a range of ± 10 degrees from the preoperatively planned target. A total of 39 patients met the inclusion criteria.

RESULTS

The mean planned OI for each patient was 40.8 (range, 40 to 41) degrees, and the mean measured postoperative OI was 40.4 (range, 37 to 46) degrees (P = 0.40), resulting in a mean absolute error of 1.8 (range, zero to five) degrees. The mean planned OA was 30.2 (range, 25 to 35) degrees, and the mean measured postoperative OA was 31.1 (range, 27 to 42) degrees (P = 0.11), resulting in a mean absolute error of 2.0 (range, zero to six) degrees. There were no outliers in either OI or OA.

CONCLUSIONS

The results of this study suggest that the use of MR navigation during THA results in accurate postoperative acetabular component inclination and anteversion relative to the preoperative plan without outliers.

Computer-aided robotics for applications in fracture reduction surgery: Advances, challenges, and opportunities

The advancement of information technology and AI has boosted global economic and social development. Robot systems (RS) and computer-aided technology (CAT) are used in various domains, including social production and human existence. Traditional fracture reduction surgery relies on the expertise and surgical skills of surgeons to realign fractures in patients. Researchers have developed robotic and assisted systems to automate fracture reduction surgery in recent decades. Computer-aided fracture reduction robot system (CARS) is used to replace the manual reduction performed by conventional physicians. A partial CARS has been used successfully in clinical fracture reduction surgery. This study provides an overview of CARS. First, the RS and CAT used in fracture reduction surgery are overviewed. Furthermore, a comprehensive analysis of CARS is presented, encompassing their design, experimental validation, and clinical applications, while highlighting recent advancements and potential future directions in this domain. The suggested CARS for fracture reduction are compared in different ways. The learning curve and technical ethics of CARS are summarized. The paper addresses unresolved research gaps and technical challenges, providing recommendations to guide future study.

Accelerometer-based portable navigation system shows no superior accuracy over pelvic alignment guide for acetabular cup placement in total hip arthroplasty in lateral decubitus position

BACKGROUND

Total hip arthroplasty (THA) using a portable navigation system (PNS) incurs costs per procedure. However, it does not require a large console. This study aimed to compare the accuracy of acetabular cup placement using a pelvic alignment guide (PAG) attached to the pelvis and an accelerometer-based PNS in THA performed in the lateral decubitus position.

METHODS

We retrospectively analyzed 100 hips that underwent primary THA in the lateral decubitus position between July 2018 and January 2021. The PAG was used in 50 hips, whereas the PNS was used in the other 50. Cup placement accuracy was measured using postoperative computed tomography scans, comparing errors in inclination and anteversion angles. The surgical time, blood loss, and complications were recorded. The follow-up period was at least 2 years in all cases.

RESULTS

The mean absolute error of the inclination angle was similar between the groups (the PAG group: 3.7° ± 2.3° [range, 0.0-9.0]; the PNS group: 3.7° ± 2.3° [range, 0.2-10.5], p = 0.705). The mean absolute error of the anteversion angle was significantly smaller in the PAG group than in the PNS group (3.0° ± 2.4° [range, 0.0-9.7] vs. 6.5° ± 4.8° [range, 0.3-17.3], p < 0.001). The PAG group had a higher proportion of hips within 5° and 10° of the target angle (64 vs. 42%, P = 0.028, and 100 vs. 74%, p < 0.001, respectively). The PNS group had six hips with anteversion errors of 15° or more. Surgical time and blood loss were lower in the PAG group. The PNS group had one dislocation, whereas the PAG group did not.

CONCLUSION

The accelerometer-based PNS did not demonstrate superior cup alignment accuracy compared to the PAG in THA performed in the lateral decubitus position. This finding informs surgeons that computer-assisted surgery is not necessarily superior to conventional THA using a PAG.

Functional Acetabular Component Positioning During Direct Anterior Approach Hip Arthroplasty Using a Novel Three-Dimensional Virtual Mesh Imaging System With Fluoroscopy

BACKGROUND

Optimal position of total hip arthroplasty (THA) components is critical for joint mechanics and stability. Acetabular component positioning during supine surgery in direct anterior approach (DAA) THA may be different in the standing position postoperatively, which traditional fluoroscopy is unable to predict. A novel 3-dimensional (3D) image analysis technology (IAT) that uses artificial intelligence to measure the tilt and rotation of the pelvis has enabled prediction of component positioning from supine to standing. The purpose of this study was to compare intraoperative fluoroscopy, non-3D-IAT, and 3D-IAT with postoperative standing radiographs to assess the accuracy of component positioning.

METHODS

From 2022 to 2023, 30 consecutive patients (86.6% women, mean age 59 [range, 55 to 67]) undergoing primary DAA THA with the use of the 3D-IAT were identified. A separate cohort of 148 patients from 2020 to 2021 (85% women, mean age 65 [range, 55 to 69]) who underwent DAA THA with non-3D-IAT was used for comparison. Leg length discrepancy (LLD), cup anteversion, and inclination were manually measured on intraoperative fluoroscopic images and digitally measured using IAT. Follow-up evaluation occurred at 1 month with standing pelvis radiographs measured using Ein Bild Röntgen Analyze-Cup software. Measurements were compared via Wilcoxon signed rank tests where P ≤ .05 indicates significantly different measurements.

RESULTS

Median LLD, inclination, and anteversion measurements via non-3D-IAT and fluoroscopy were significantly different compared to postoperative standing radiographs (P < .001). The 3D-IAT more accurately predicted LLD, abduction, and anteversion, with values not significantly different from postoperative standing measurements (P = .23, P = .93, and P = .36, respectively).

CONCLUSIONS

The use of the 3D-IAT during DAA THA allowed for the more accurate prediction of acetabular component position in the standing position postoperatively.

Use of Computer Navigation for Optimal Acetabular Cup Placement in Revision Total Hip Arthroplasty: Case Reports and Surgical Techniques

Background

The outcomes of revision total hip arthroplasty (rTHA) have become increasingly important as their volume increases. Computer navigation, a reliable method to improve component positioning during primary total hip arthroplasty (THA), is not well studied in the rTHA setting. Given that dislocation rates following rTHA are significantly higher than those of primary THA, component positioning becomes paramount in these cases.

Methods

Here, we present two case reports and surgical techniques, one of a 77-year-old man undergoing rTHA for recurrent hip instability following primary THA, and one of a 61-year-old woman undergoing rTHA for severe iliopsoas bursitis who was at increased risk for instability and dislocation given her history of large segment spinal fusion.

Results

Both patients achieved optimal acetabular component positioning after rTHA with imageless computer navigation.

Conclusions

The use of imageless computer navigation in rTHA provides accurate and reproducible component positioning during acetabular rTHA.

Accuracy of cup placement compared with preoperative surgeon targets in primary total hip arthroplasty using standard instrumentation and techniques: a global, multicenter study

BACKGROUND

Acetabular cup positioning in total hip arthroplasty (THA) is closely related to outcomes. The literature has suggested cup parameters defined by the Lewinnek safe zone; however, the validity of such measures is in question. Several studies have raised concerns about the benefits of using the Lewinnek safe zone as a predictor of success. In this study we elected to use prospective surgeon targets as the basis for comparison to see how successful surgeons are positioning their cup using standard instruments and techniques.

METHODS

A prospective, global, multicenter study was conducted. Cup positioning success was defined as a composite endpoint. Both cup inclination and version needed to be within 10° of the surgeon target to be considered a success. Radiographic analysis was conducted by a third-party reviewer.

RESULTS

In 170 subjects, inclination, target versus actual, was 44.8° [standard deviation (SD 0.9°)] and 43.1° (SD 7.6°), respectively (p = 0.0029). Inclination was considered successful in 84.1% of cases. Mean version, target versus actual, was 19.4° (SD 3.9°) and 27.2° (SD 5.6°), respectively (p < 0.0001). Version was considered successful in 63.4% of cases, and combined position (inclination and version) was considered successful in 53.1%.

CONCLUSION

This study shows that with traditional methods of placing the cup intraoperatively, surgeons are only accurate 53.1% of the time compared with a predicted preoperative plan. This study suggests that the inconsistency in cup positioning based on the surgeon's planned target is potentially another important variable to consider while using a mechanical guide or in freehand techniques for cup placement in THA.

TRIAL REGISTRATION

This study is registered on ClinicalTrials.gov, NCT03189303.

Contemporary analysis of the learning curve for robotic-assisted total hip arthroplasty emerging technologies

Robotic assisted (RA) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting novel platforms challenging. Therefore, we conducted a systematic review to assess the learning curve associated with RA-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA). PubMed, MEDLINE, EBSCOhost, and Google Scholar were searched on June 16, 2023, to identify studies published between January 1, 2000 and June 16, 2023 (PROSPERO registration: CRD42023437339). The query yielded 655 unique articles, which were screened for eligibility. The final analysis included 11 articles, evaluating 1351 THA procedures. Risk of bias was assessed via the Methodological Index for Nonrandomized Studies (MINORS) tool. The mean MINORS score was 21.3 ± 0.9. RA-THA provided immediate improvements in acetabular component placement accuracy and radiographic outcomes compared to M-THA, with little to no experience required to achieve peak proficiency. A modest learning curve (12-17 cases) was associated with operative time, which was elevated compared to M-THA (+ 9-13 min). RA-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes. Surgeons should expect to experience increased operative times, which become less pronounced or equivalent to M-THA after a modest caseload.

Navigating the learning curve: assessing caseload and comparing outcomes before and after the learning curve of computer-navigated total hip arthroplasty

PURPOSE

Computer-navigated (CN) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting a novel platform challenging. Therefore, we conducted a systematic review to assess the learning curve associated with CN-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA).

METHODS

A search was conducted using PubMed, MEDLINE, EBSCOhost, and Google Scholar on June 16, 2023 to find research articles published after January 1, 2000 (PROSPERO registration: CRD4202339403) that investigated the learning curve associated with CN-THA. 655 distinct articles were retrieved and subsequently screened for eligibility. In the final analysis, nine publications totaling 847 THAs were evaluated. The Methodological Index for Nonrandomized Studies (MINORS) tool was utilized to evaluate the potential for bias, with the mean MINORS score of 21.3 ± 1.2.

RESULTS

CN-THA showed early advantages to M-THA for component placement accuracy and radiographic outcomes but longer operative times (+ 3- 20 min). There was a learning curve required to achieve peak proficiency in these metrics, though mixed methodologies made the required caseload unclear.

CONCLUSIONS

CN-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes, though CN-THA's advantages become more pronounced with experience. Surgeons should anticipate longer operative times during the learning curve for CN-THA, which lessen following a modest caseload. A more thorough evaluation of novel computer-navigated technologies would be enhanced by adopting a more uniform method of defining learning curves for outcomes of interest. Registration PROSPERO registration of the study protocol: CRD42023394031, 27 June 2023.

Optimization of Acetabular Cup Abduction by Adjusting Pelvic Pitch

Background

The purposes of this study were to determine the accuracy of our cup positioning method and to evaluate the dislocation rate after total hip arthroplasty (THA).

Methods

After positioning the patient in the lateral decubitus position on the operation table, an anteroposterior view of the hip was taken. The pelvic pitch was measured on the X-ray. A positive pitch was defined as the caudal rotation of the upper hemipelvis. Our target abduction of the cup was 43°. We used the cup holder to guesstimate the cup abduction. In a preliminary study, we found that the weight of the cup holder increased the pelvic pitch by 5°. Thus, the target abduction of the cup holder was calculated by a formula: 43° - pelvic pitch - 5°. During the cup insertion, the cup holder was anteverted to the calculated target according to the concept of combined anteversion. We evaluated 478 THAs (429 patients), which were done with the use of the method.

Results

The mean cup abduction was 43.9° (range, 32.0°-53.0°) and the mean error of cup abduction was 2.4° (standard deviation [SD], 2.0°; range, 0.0°-11.0°). The mean cup anteversion was 28.5° (range, 10.0°-42.0°) and the mean error of cup anteversion was 6.7° (SD, 5.2°; range, 0.0°-27.6°). Of all, 82.4% of the cups (394 / 478) were within the safe zone: 30°-50° abduction and 10°-35° anteversion. During 2- to 5-year follow-up, no hip dislocated.

Conclusions

Our adjusting method according to the pelvic pitch can be a reliable option for optimizing the cup abduction in THA.

Advancements in robotic surgery: innovations, challenges and future prospects

The use of robots has revolutionized healthcare, wherein further innovations have led to improved precision and accuracy. Conceived in the late 1960s, robot-assisted surgeries have evolved to become an integral part of various surgical specialties. Modern robotic surgical systems are equipped with highly dexterous arms and miniaturized instruments that reduce tremors and enable delicate maneuvers. Implementation of advanced materials and designs along with the integration of imaging and visualization technologies have enhanced surgical accuracy and made robots safer and more adaptable to various procedures. Further, the haptic feedback system allows surgeons to determine the consistency of the tissues they are operating upon, without physical contact, thereby preventing injuries due to the application of excess force. With the implementation of teleoperation, surgeons can now overcome geographical limitations and provide specialized healthcare remotely. The use of artificial intelligence (AI) and machine learning (ML) aids in surgical decision-making by improving the recognition of minute and complex anatomical structures. All these advancements have led to faster recovery and fewer complications in patients. However, the substantial cost of robotic systems, their maintenance, the size of the systems and proper surgeon training pose major challenges. Nevertheless, with future advancements such as AI-driven automation, nanorobots, microscopic incision surgeries, semi-automated telerobotic systems, and the impact of 5G connectivity on remote surgery, the growth curve of robotic surgery points to innovation and stands as a testament to the persistent pursuit of progress in healthcare.

Rigid fixation of pelvic tracker essential for accurate cup placement in CT-based navigation total hip arthroplasty

Research is lacking on the effect of intraoperative pelvic tracker displacement relative to the pelvis on cup orientation accuracy in computed tomography (CT)-based navigation (CTN) or multivariable analysis to detect factors associated with CTN accuracy. Here, we asked: (1) how pelvic tracker displacement influences the CTN accuracy of cup orientation in total hip arthroplasty (THA)? and (2) what factors are associated with CTN accuracy on multivariable analysis? Regarding cup orientation in 446 THA procedures using CTN, we evaluated clinical error defined as the difference between postoperative measurement and preoperative planning and measurement error defined as the difference between postoperative and intraoperative measurements. Multivariable regression analyses detected the associated factors. Subjects with an intraoperative tracker displacement of < 2 mm were classified in the verified group. Mean absolute clinical and measurement errors were < 1.5° in the verified group, whereas the measurement error of 2.6° for cup inclination and 1.3° for anteversion was larger in the non-verified versus verified group. Tracker displacement and screw fixation were associated with larger clinical errors, while tracker displacement and surgeon inexperience were associated with larger measurement errors. Clinical and measurement accuracies were high for CTN cup placement with rigid pelvic tracker fixation.

Artificially Intelligent Three-Dimensionally-Printed Patient-Specific Instrument Improves Total Hip Arthroplasty Accuracy

BACKGROUND

Patient-specific instrumentation (PSI) has the potential to improve the accuracy of implant positioning in total hip arthroplasty (THA). This prospective clinical study aimed to develop artificial intelligence to increase PSI production efficiency and assess accuracy, clinical outcomes, and learning curves.

METHODS

A convolutional neural network was applied to automatically process computer tomography images. PSI size and position were designed to guide the acetabular preparation and femoral neck resection. Thirty patients who underwent PSI-assisted THAs were matched to thirty patients who underwent free-hand THAs, and the component positions, as well as radiographic and clinical outcomes were analyzed.

RESULTS

PSI-assisted THA was significantly more accurate than free-hand THA at achieving the target component position. The mean absolute errors of cup inclination (P = .004) and anteversion (P < .001) were significantly smaller in the PSI group with fewer outliers. Calcar length (P = .002) and neck length (P = .026) were also more accurate in the PSI group. The leg length discrepancy was significantly lower in the PSI group (P = .002). There were no significant differences in operation time, blood loss, leg length discrepancy, or cup position among the first, second, and last 10 cases.

CONCLUSION

PSI-assisted THA offered more accurate component positions and better radiographic outcomes than free-hand THA. There was no evidence of a learning curve. Our findings suggest that PSI is a convenient and practical option to help surgeons achieve accurate surgical outcomes.

Does robot-assisted surgery reduce leg length discrepancy in total hip replacement? Robot-assisted posterior approach versus direct anterior approach and manual posterior approach: a propensity score-matching study

BACKGROUND

Advocates of robot-assisted technique argue that robots could improve leg length restoration in total hip replacement. However, there were few studies to compare the robot-assisted posterior approach (RPA) with conventional posterior approach (PA) THA and direct anterior approach (DAA) THA in LLD. This study aimed to determine whether robot-assisted techniques could significantly reduce LLD compared to manual DAA and manual PA.

METHODS

We retrospectively reviewed the cohort of consecutive ONFH patients who underwent THA robot-assisted posterior, manual posterior, and manual DAA from January 2018 to December 2020 in one institution. One experienced surgeon performed all procedures. We calculated the propensity score to match similar patients in different groups by multivariate logistic regression analysis for each patient. We included confounders consisting of age at the time of surgery, sex, body mass index (BMI), and preoperative LLD. Postoperative LLD and Harris hip scores (HHS) at two years after surgery of different cohorts were compared.

RESULT

We analyzed 267 ONFH patients treated with RPA, DAA, or PA (73 RPA patients, 99 DAA patients, and 95 PA patients). After propensity score matching, we generated cohorts of 40 patients in DAA and RPA groups. And we found no significant difference in postoperative LLD between RPA and DAA cohorts (4.10 ± 3.50 mm vs 4.60 ± 4.14 mm, p = 0.577) in this study. The HHS at 2 years postoperatively were 87.04 ± 7.06 vs 85.33 ± 8.34 p = 0.202. After propensity score matching, we generated cohorts of 58 patients in manual PA and RPA groups. And there were significant differences in postoperative LLD between the RPA and PA cohorts. (3.98 ± 3.27 mm vs 5.38 ± 3.68 mm, p = 0.031). The HHS at 2 years postoperatively were 89.38 ± 6.81 vs 85.33 ± 8.81 p = 0.019. After propensity score matching, we generated cohorts of 75 patients in manual DAA and PA groups. And there were significant differences in postoperative LLD between the DAA and PA cohorts. (4.03 ± 3.93 mm vs 5.39 ± 3.83 mm, p = 0.031) The HHS at 2 years postoperatively were 89.71 ± 6.18 vs 86.91 ± 7.20 p = 0.012.

CONCLUSION

This study found no significant difference in postoperative LLD between RPA and DAA, but we found a significant difference between RPA and manual PA, DAA and manual PA in ONFH patients. We found a significant advantage in leg length restoration in primary total hip arthroplasty with robot-assisted surgery.

Accuracy of cup placement using computed tomography-based navigation system in total hip arthroplasty through the direct anterior approach

BACKGROUND

This study aimed to elucidate the accuracy of cup placement with the computed tomography (CT)-based navigation system (CTN) in the direct anterior approach (DAA)-total hip arthroplasty (THA) in the supine position compared with the mechanical cup alignment guide (MG) or the fluoroscopy (FS).

METHODS

A total of 171 hips of 156 patients undergone primary THA were classified into the following three groups (the MG group: 63 hips, the FS group: 58 hips, the CTN group: 50 hips). Comparing the preoperative planning with postoperative CT measurement by three-dimensional templating software, the accuracy of cup placement was investigated in the three groups.

RESULTS

There were significant differences in the mean absolute error of radiographic inclination (RI) between the MG group (4.4° ± 3.2°) and the CTN group (2.8° ± 2.5°) (p = 0.01). The mean absolute error of radiographic anteversion (RA) also showed significant differences between the CTN group (2.8° ± 1.9°) and the MG group (5.8° ± 4.7°) (p = 0.0001) or the FS group (4.8° ± 4.1°) (p = 0.02). Regarding the cup center position, the mean absolute error of vertical position from preoperative planning was the smallest in the CTN group (1.8 ± 1.4 mm) compared with those in other groups (MG: 3.3 ± 3.2 mm, p = 0.007, FS: 3.2 ± 3.0 mm, p = 0.017).

CONCLUSION

The CTN guarantees accurate cup placement in the DAA-THA in the supine position compared with the MG and FS groups.

Investigating sagittal spinal alignment, low back pain, and clinical outcomes after total hip arthroplasty for lumbar hyperlordosis: a retrospective study

INTRODUCTION

Hip-spine syndrome, wherein flexion deformity of the hip might exaggerate normal lumbar lordosis (LL), was first described in 1983. It could result in subluxation of the posterior facets and cause low back pain (LBP). However, the clinical outcomes of total hip arthroplasty (THA) and spinal alignment changes in patients with lumbar hyperlordosis (hyper LL) remain unknown. We aimed to clarify the proportion of patients with hyper LL before THA and compare pre- and post-operative sagittal spinal alignment, LBP, and clinical outcomes between patients with hyper LL and those with normal LL.

MATERIALS AND METHODS

We investigated 278 patients who underwent primary THA between December 2015 and December 2019. Spine radiographs in the standing position were examined preoperatively and 1 year postoperatively. Patients with hyper LL were defined as having a pelvic incidence (PI) minus LL of < - 9° preoperatively. The control group included age- and sex-matched patients with normal LL, defined by a PI minus LL of - 9° to 9°. Clinical outcomes were evaluated using the visual analogue scale (VAS) for LBP, Harris hip score (HHS), Oxford hip score (OHS), and University of California, Los Angeles (UCLA) activity score.

RESULTS

Thirty-eight patients (13.7%) had hyper LL, and they exhibited a lower pelvic tilt, lower sagittal vertical axis, and greater sigmoid curvature than did the controls. Evaluation of changes in the spinal alignment after surgery showed that the pelvis tilted more posteriorly, and LL decreased more in the hyper LL group than in the control group. Pre- and post-operative VAS for LBP, HHS, OHS, and UCLA activity scores were not significantly different between the two groups.

CONCLUSION

Hyper LL in patients with hip osteoarthritis had no adverse effects on LBP and the clinical outcomes of THA. Hyper LL may partially result from a flexible and adaptable lumbo-pelvic structure.

Digital Radiography During Total Hip Arthroplasty: Early Results With a Combined Anteversion Technique

Ideal component positioning is critical to outcomes in total hip arthroplasty. We describe our early results using digital radiographs with a combined ante-version technique. We report the incidence of component adjustments made based on digital radiographs and show how this technology can be used during patient positioning to achieve appropriate starting pelvic alignment. We reviewed 176 cases of primary total hip arthroplasty performed by a single arthroplasty surgeon using a posterior approach. Mean follow-up was 1 year (range, 3 months to 2.7 years). Digital radiographs (Surgeon's Checklist Hip; Radlink) and a combined anteversion technique were used for component positioning. For a subset of 100 patients, we recorded the incidence of pelvic mal-positioning found on digital radiographs obtained during initial positioning of the patient. For this same subset we also detail the component changes made as a result of intraoperative radiographs during trialing. Among 176 cases we have had 2 (1.1%) postoperative dislocations. Both underwent closed reduction with no further dislocation. We have had no revisions and 1 intraoperative calcar fracture. For our 100-case subset, digital radiographs during patient positioning identified pelvic malpositioning greater than 5° (coronal or axial plane) among 17% of cases. During trialing, we made component adjustments 71% of the time because of findings on intraoperative imaging. Digital radiography can be a valuable tool for component positioning during total hip arthroplasty. We experienced favorable early outcomes and show the utility of digital radiographs for proper pelvic positioning and making intraoperative adjustments to achieve optimal component placement. [Orthopedics. 2022;45(4):221-226.].

Orthopedic Surgeons' Accuracy When Orienting an Acetabular Cup. A Comparison with Untrained Individuals

Background and Objectives: Previous studies demonstrated a huge variability among surgeons when it comes to reproducing the position of an acetabular cup in total hip arthroplasty. Our main objective is to determine if orthopedic surgeons can replicate a given orientation on a pelvic model better than untrained individuals. Our secondary objective is to determine if experience has any influence on their ability for this task. Materials and Methods: A group of specialist orthopedic hip surgeons and a group of volunteers with no medical training were asked to reproduce three given (randomly generated) acetabular cup orientations (inclination and anteversion) on a pelvic model. Error was measured by means of a hip navigation system and comparisons between groups were made using the appropriate statistical methods. Results: The study included 107 individuals, 36 orthopedic surgeons and 71 untrained volunteers. The mean error among surgeons was slightly greater as regards both inclination (7.84 ± 5.53 vs. 6.70 ± 4.03) and anteversion (5.85 ± 4.52 vs. 5.48 ± 3.44), although statistical significance was not reached (p = 0.226 and p = 0.639, respectively). Similarly, although surgeons with more than 100 procedures a year obtained better results than those with less surgical experience (8.01 vs. 7.67 degrees of error in inclination and 5.83 vs. 5.87 in anteversion), this difference was not statistically significant, either (p = 0.852 and p = 0.981). Conclusions: No differences were found in the average error made by orthopedic surgeons and untrained individuals. Furthermore, the surgeons' cup orientation accuracy was not seen to improve significantly with experience.

Robotic total hip arthroplasty for fused hips in ankylosing spondylitis patients: Our experience with robotic arm technology

The conversion from a fused hip to conventional total hip arthroplasty (THA) in patients with ankylosing spondylitis can be challenging. The problems are related to patient positioning, surgical exposure, femoral neck osteotomy, identifying the true acetabulum, and proper implant positioning. This case series describes our experience using the Mako Robotic-Arm in four bilateral THA procedures (each conducted in a single session) and one unilateral procedure in a fifth patient. Robotic total hip arthroplasty (RTHA) simplified THA by providing real-time information on the relative positions of the femur, pelvis, instruments, and implants to guide the surgery and implant placement.

Cup placement in primary total hip arthroplasty: how to get it right without navigation or robotics

Acetabular component orientation and position are important factors in the short- and long-term outcomes of total hip arthroplasty.

Different definitions of inclination and anteversion are used in the orthopaedic literature and surgeons should be aware of these differences and understand their relationships.

There is no universal safe zone.

Preoperative planning should be used to determine the optimum position and orientation of the cup and assess spinopelvic characteristics to adjust cup orientation accordingly.

A peripheral reaming technique leads to a more accurate restoration of the centre of rotation with less variability compared with a standard reaming technique.

Several intraoperative landmarks can be used to control the version of the cup, the most commonly used and studied is the transverse acetabular ligament.

The use of an inclinometer reduces the variability associated with the use of freehand or mechanical alignment guides.

A method combining the use of a mobile application and a dedicated pelvic positioner for acetabular cup insertion

Background

We developed a mobile device application and dedicated pelvic positioner with the aim of improving the acetabular cup placement accuracy in patients undergoing total hip arthroplasty (THA). The function of the application was to display the intra-operative cup angle. The accuracy and clinical usefulness of this combined method were verified through comparison with the conventional alignment guide method.

Methods

In total, 60 patients who underwent cementless THA were included in this study. We compared the cup alignment when using this combined method with that when using the conventional alignment guide method. The absolute value error between the intra- and post-operative angles of inclination and anteversion of the cup was calculated.

Results

The absolute value error of inclination was 2.4° ± 2.1° in the study group and 4.0° ± 3.3° in the control group (P = 0.107). The absolute value error of anteversion was 2.8° ± 2.6° in the study group and 7.4° ± 5.3° in the control group (P < 0.001).

Conclusion

Using the application and pelvic positioner is simple and can be introduced at a low cost. The more accurate measurement of the intra-operative cup angle using this combined method has improved the cup insertion accuracy compared with that of the conventional alignment guide method.

THA with Use of Patient-Specific Resurfacing Jigs and a Novel Customized Implant Design

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Conventional total hip arthroplasty (THA) largely remains an unguided procedure dependent on the ability and experience of the surgeon. New technologies, such as patient-specific instrumentation and robotics, have shown promising results in improving implant positioning, which has the potential to improve patient outcomes.

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The use of off-the-shelf (OTS) implant designs, however, limits the success of the technological advances since they are unable to recreate the native anatomy of the joint. The inability to restore femoral offset and version or the presence of implant-related leg-length discrepancies often lead to suboptimal surgical results that increase the risk of dislocation, fractures, and component wear, compromising postoperative functional outcomes and implant longevity.

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A customized THA system, whereby the femoral stem is designed to restore patient anatomy, has recently been introduced. The THA system uses computed tomography (CT)-derived 3D imaging to create a custom stem, patient-specific component placement, and patient-specific instrumentation that matches the patient's native anatomy.

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The purpose of this article is to provide information on the design and manufacturing process of this new THA implant, to illustrate the associated preoperative planning, and to describe the surgical technique; 3 surgical cases are presented.

Computer Navigation for Revision Total Hip Arthroplasty Reduces Dislocation Rates

Purpose

Computer navigation in total hip arthroplasty (THA) offers potential for more accurate placement of acetabular components, avoiding impingement, edge loading, and dislocation, all of which can necessitate revision THA (rTHA). Therefore, the use of computer navigation may be particularly beneficial in patients undergoing rTHA. The purpose of this study was to determine if the use of computer-assisted hip navigation reduces the rate of dislocation in patients undergoing rTHA.

Methods

A retrospective review of 72 patients undergoing computer-navigated rTHA between February 2016 and May 2017 was performed. Demographics, indications for revision, type of procedure performed, and incidence of postoperative dislocation were collected for all patients. Clinical follow-up was recorded at 3 months, 1 year and 2 years.

Results

All 72 patients (48% female; 52% male) were included for analysis. The mean age was 70.4 ± 11.2 years and mean BMI was 26.4 ± 5.2 kg/m². 22 of 72 patients (31%) required a rTHA procedure due to instability resulting in dislocation. At 3 months, 1 year, and 2 years, there were no dislocations (0%). There was a significant reduction in dislocation rate after computer-navigated rTHA (0%) relative to that following primary THA in the same patient cohort (31%; p < 0.05).

Conclusion

Our study demonstrates a significant reduction in dislocation rate following rTHA with computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer navigation may help to curtail femoral and acetabular malalignment in rTHA.

Level of Evidence

Level III: retrospective.

The Use of Technology to Achieve the Functional Acetabular Safe Zone in Total Hip Arthroplasty

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Functional acetabular safe zones based on patient-specific factors during total hip arthroplasty are theorized to result in more optimal component stability than the use of traditional safe zones based on static targets.

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Preoperative planning that takes into account functional pelvic positions and spinopelvic mobility is increasingly recommended.

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Computer navigation and robotics can be utilized to help accurately achieve the targeted cup position within the functional safe zone.

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Each technology platform (imageless and image-based computer navigation and robotics) utilizes a specific referencing method for the pelvis, which influences anteversion and inclination values.

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The purpose of this article is to summarize how these different systems reconcile differences in pelvic referencing to ensure that the surgeon achieves the targeted functional cup position.

Comparison between freehand technique and computed tomography-based navigation in acetabular cup placement through direct anterior approach for total hip arthroplasty

INTRODUCTION

In total hip arthroplasty (THA), improper cup orientation can result in dislocation, early excessive polyethylene wear, and pain following THA. The supine position during THA provides a more reproducible functional pelvic position than the lateral decubitus position and may allow freehand cup placement as reliable as that obtained by computer navigation. The purpose of this study was to investigate the accuracy of freehand cup placement through a supine direct anterior approach (DAA) compared with computed tomography (CT)-based navigation.

MATERIALS AND METHODS

The same surgeon performed primary cementless THA through the DAA in 144 supine patients. Seventy-two patients underwent freehand cup placement with standard mechanical guidance-oriented radiographic target cup positioning, and 72 underwent placement with CT-based navigation guidance. Using three-dimensional templating software, the study group calculated cup inclination and anteversion on postoperative CT scans.

RESULTS

The navigation method resulted in a significantly smaller deviation of inclination from the target (p < 0.05); the difference in anteversion was not significant. In addition, the navigation method resulted in significantly fewer cups placed ± 10° outside the target position (0% for inclination, 0% for anteversion) than did the freehand procedure (26% for inclination, 25% for anteversion) (p < 0.0001).

CONCLUSIONS

Freehand cup placement is less reliable even in the supine position. Use of a CT-based navigation system can significantly improve cup positioning in THA through the DAA by reducing the incidence of outliers.

Differences in the setting of acetabular component alignment guides between the supine and lateral positions for total hip arthroplasty

The acetabular component orientation in total hip arthroplasty is of critical importance to clinical results. Although navigation systems and surgical robots have been introduced, most surgeons still use acetabular component alignment guides. This study aimed to compare the accuracy between modern acetabular component alignment guides for the lateral position and those for the supine position. Thirteen alignment guides for the lateral position and 10 for the supine position were investigated. All the lateral position alignment guides indicated cup alignment in operative definition, and the supine position alignment guides indicated cup alignment in radiographic definition. For lateral position alignment guides, the anteversion actually indicated by the alignment guide itself was smaller than that indicated by the manufacturer by a mean of 6° (maximum, 9°), and the inclination actually indicated by alignment guides themselves was larger than that by the manufacturer (p < 0.01) by a mean of 2° (maximum, 4°). For supine position alignment guides, the inclination and anteversion indicated by the alignment guide itself were identical with those indicated by the manufacturer. The current study showed that the angles actually indicated and those stated by manufacturers were not identical for lateral position alignment guides.

Mechanical and Anatomical Alignment Guide Techniques Are Superior to Freehand in Achieving Target Orientation of an Acetabular Component

Background

Achieving accurate and consistent acetabular component orientation remains a major challenge in total hip arthroplasty.

Methods

We used a pelvic model to compare freehand techniques vs mechanical and anatomical alignment guides in achieving a target operative inclination (OI) and operative anteversion (OA). Thirty subjects comprising consultant orthopedic surgeons, orthopedic trainees, and nonsurgical staff positioned an acetabular component in a pelvic model using 3 different methods for guiding inclination and another 3 for guiding version.

Results

Using either a standard mechanical alignment guide (MAG) or a spirit level MAG technique eliminated outliers from target OI, while the freehand method resulted in 46.7% of measurements outside the OI target range. The spirit level MAG technique significantly outperformed the standard MAG technique in median unsigned deviation from target OI (0.8° vs 2.1°, P < .001). Either method of referencing the transverse acetabular ligament for version yielded lower deviations from target OA than the freehand method and fewer outliers from the ±5° target range. Surgical experience was not a significant factor for accurately achieving target OI and OA.

Conclusions

Even in an idealized in vitro model, a wide range of OI and OA is seen with the freehand technique of cup placement by subjects of all levels of surgical experience. Using either a standard MAG or a spirit level MAG reduces deviations in target OI, with the spirit level MAG method yielding the best accuracy. Using the transverse acetabular ligament to guide cup anteversion yields more accurate OA.

The Accuracy of Patient-Specific Instrumentation with Laser Guidance in a Dynamic Total Hip Arthroplasty: A Radiological Evaluation

The functional positioning of components in a total hip arthroplasty (THA) and its relationship with individual lumbopelvic kinematics and a patient’s anatomy are being extensively studied. Patient-specific kinematic planning could be a game-changer; however, it should be accurately delivered intraoperatively. The main purpose of this study was to verify the reliability and accuracy of a patient-specific instrumentation (PSI) and laser-guided technique to replicate preoperative dynamic planning. Thirty-six patients were prospectively enrolled and received dynamic hip preoperative planning based on three functional lateral spinopelvic X-rays and a low dose CT scan. Three-dimensional (3D) printed PSI guides and laser-guided instrumentation were used intraoperatively. The orientation of the components, osteotomy level and change in hip length and offset were measured on postoperative CT scans and compared with the planned preoperative values. The length of surgery was compared with that of a matched group of thirty-six patients who underwent a conventional THA. The mean absolute deviation from the planned inclination and anteversion was 3.9° and 4.4°, respectively. In 92% of cases, both the inclination and anteversion were within +/− 10° of the planned values. Regarding the osteotomy level, offset change and limb length change, the mean deviation was, respectively, 1.6 mm, 2.6 mm and 2 mm. No statistically significant difference was detected when comparing the planned values with the achieved values. The mean surgical time was 71.4 min in the PSI group and 60.4 min in the conventional THA group (p < 0.05). Patient-specific and laser-guided instrumentation is safe and accurately reproduces dynamic planning in terms of the orientation of the components, osteotomy level, leg length and offset. Moreover, the increase in surgical time is negligible.

Comparison of the accuracy of the cup position and orientation in total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip between the Mako robotic arm-assisted system and computed tomography-based navigation

PURPOSE

We investigated the accuracy of the acetabular cup position and orientation in robotic-assisted total hip arthroplasty (rTHA) compared to navigated THA (nTHA) using computed tomography (CT) for patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH).

METHODS

We studied 31 hips of 28 patients who underwent rTHA and 119 hips of 112 patients who underwent nTHA with the same target cup orientation. After propensity score matching, each group comprised 29 hips. Post-operative cup position and orientation were measured from the postoperative CT data. Errors from the target cup position and orientation were compared between the two groups.

RESULTS

Post-operatively, the absolute error of the anteroposterior and superoinferior cup positions from the target position was significantly lower in the rTHA group than in the nTHA group. The change in the post-operative radiographic inclination from the target orientation was lower in the rTHA group than in the nTHA group. Screw fixation for cup implantation was required for three hips in the nTHA group but not in the rTHA group.

CONCLUSION

rTHA achieved more precise cup implantation with reduced variation from the target orientation compared to nTHA in patients with osteoarthritis secondary to DDH.

Accuracy of a portable accelerometer-based navigation system for cup placement and intraoperative leg length measurement in total hip arthroplasty: a cross-sectional study

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 a leg length measurement function. The purposes of this study were to investigate cup positioning and to examine the accuracy of leg length measurement with New HipAlign.

Methods

Cups were implanted and intraoperative leg length change was measured using New HipAlign in 60 THAs through a posterior approach in the lateral decubitus position. The cup position and radiographic leg length change were determined postoperatively on pelvic radiograph and computed tomography scans. We previously compared cup positioning with a previous version of a portable, accelerometer-based hip navigation system (Previous HipAlign) and conventional surgical techniques. Cup positioning in this study was compared with the results of out previous study using Previous HipAlign.

Results

The mean cup abduction of 40.3° ± 4.9° (range, 26° to 53°) and the mean cup anteversion of 15.8° ± 5.6° (range, 6.7° to 29.5°) were found. The deviation of the postoperative measured angles from the target cup position was 3.7° ± 3.3° for cup abduction and 5.9° ± 3.6° for cup anteversion. 56/60 of the cups were inside the Lewinnek safe zone. Compared with our previous study using Previous HipAlign, there were no significant differences with regard to cup abduction, cup anteversion, the deviation from the target cup position for cup abduction, the value of deviation for cup anteversion, and the number of cups inside the Lewinnek safe zone (P = 0.218, 0.334, 0.651, 0.797, 0.592). The mean difference between the intraoperative and radiographic leg length changes was + 0.8 ± 3.4 mm. There was significant correlation between the intraoperative and radiographic leg length changes (r = 0.804, P = 0.000).

Conclusions

Use of New HipAlign allowed for accurate cup placement and reliable leg length measurement during THA.

Trial registration

Clinical trial is defined as ‘any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcome’ by the World Health Organization (WHO). Because this study is not a clinical trial, trial registration is not needed.

Anterior pelvic plane registration accuracy and cup position measurement using ultrasound- and pointer-based navigation in primary total hip arthroplasty

BACKGROUND

Incorrect cup positioning in primary total hip arthroplasty is known as a risk factor for early implant failure. The use of navigation systems leads to more accurate cup positioning.

OBJECTIVE

The aim of this study was to compare the registration accuracy of the anterior pelvic plane and the measurement accuracy of the definite cup position for a pointer computer-assisted orthopaedic navigation system (P-CAOS) and an ultrasound-based navigation tool (US-CAOS) in an intra-individual study design.

METHODS

Anterior pelvic plane registration was performed in 44 patients receiving a primary total hip arthroplasty with P-CAOS and US-CAOS. The cup implantation was performed using US-CAOS. Intraoperatively, the cup position was assessed using P-CAOS and US-CAOS. The postoperative cup position was determined via CT scan. Inclination and anteversion errors were calculated using intraoperative values and CT data. All operations were performed by a single, high-volume surgeon using a minimally invasive anterolateral approach.

RESULTS

The mean inclination error was 0.9∘ in the US-CAOS group and -1.1∘ in the P-CAOS group. This was not statistically significant. The mean anteversion error was significantly reduced (p< 0.001) in the US-CAOS group (1.4∘) compared to the P-CAOS group (-8.0∘). Significantly more cups (23 of 44; 52%) in the P-CAOS group were outliers regarding to the defined anteversion error range of 15∘± 10∘. Outliers in the US-CAOS group amounted to two (of 44; 5%) (p< 0.001). The number of outliers regarding the inclination error range of 40∘± 10∘, did not differ significantly between the P-CAOS (2; 5%) and US-CAOS (1; 2%) group.

CONCLUSION

We were able to show a systematic anterior pelvic plane registration error in this intraindividual study design. US-CAOS based APP landmark registration showed to be significantly more precise compared to P-CAOS registration. The anteversion error of the cup using US-CAOS showed to be significantly reduced compared to the P-CAOS method.

Accuracy of cup placement in total hip arthroplasty by means of a mechanical positioning device: a comprehensive cadaveric 3d analysis of 16 specimens

INTRODUCTION

We tested whether a mechanical device (such as Hipsecure) to pinpoint the anterior pelvic plane (APP) as a guide can improve acetabular cup placement. To assess accuracy we asked: (1) is the APP an effective guide to position acetabular cup placement within acceptable ° of divergence from the optimal 40° inclination and 15° anteversion; (2) could a mechanical device increase the number of acetabular cup placements within Lewinnek's safe zone (i.e. inclination 30° to 50°; anteversion 5° to 25°)?

METHODS

16 cadaveric specimens were used to assess the 3D surgical success of using a mechanical device APP to guide acetabular cup placement along the APP. We used the Hipsecure mechanical device to implant acetabular cups at 40° inclination and 15° anteversion. Subequently, all cadaveric specimens with implants were scanned with a CT and 3D models were created of the pelvis and acetabular cups to assess the outcome in terms of Lewinnek's safe zones.

RESULTS

The mean inclination of the 16 implants was 40.6° (95% CI, 37.7-43.4) and the mean anteversion angle was 13.4° (95% CI, 10.7-16.1). All 16 cup placements were within Lewinnek's safe zone for inclination (between 30° and 50°) and all but 2 were within Lewinnek's safe zone for anteversion (between 5° and 25°).

CONCLUSION

In cadaveric specimens, the use of a mechanical device and the APP as a guide for acetabular cup placement resulted in good positioning with respect to both of Lewinnek's safe zones.

Electromagnetic navigation system for acetabular component placement in total hip arthroplasty is more precise and accurate than the freehand technique: a randomized, controlled trial with 84 patients

Background and purpose - The accuracy of conventional navigation systems depends on precise registration of bony landmarks. We investigated the clinical use of electromagnetic navigation (EMN), with a unique device for precise determination of the anterior pelvic plane. Patients and methods - We randomly allocated patients scheduled for total hip arthroplasty into 2 groups of 42 patients each. In the study group, cups were placed at the predetermined target angles (inclination: 42.5°; anteversion: 15°) with the support of EMN. In the control group, cups were placed freehand aiming at the same target angles. Postoperatively the true position of the cup was determined using computed tomography scan of the pelvis. Precision (root mean squared error, RMSE) bias (mean bias error, ME), accuracy, and duration of surgery were compared between the methods. Results - Cup anteversion was more accurate and precise in the navigated group. The ME in the navigated and freehand group was -1.7° (95% CI -2.4 to 1.1) and -4.5° (CI -6.5 to 2.5), respectively. The RMSE in the navigated and freehand group was 2.8° (CI 2.3-3.2) and 8.0° (CI 6.3-9.5), respectively. The inclination was also more precise in the navigated group, with the RMSE in the navigated and freehand group at 4.6° (CI 3.4-5.9) and 6.5° (CI 5.4-7.5), respectively. The accuracy of the inclination and the duration of surgeries were similar between the groups. Interpretation - Cup placement with the help of EMN is more precise than the freehand technique and it does not affect the duration of surgery.

Validation of use of transverse acetabular ligament and mechanical angle guide device to orient the acetabular cup

AIM

To verify if transverse acetabular ligament (TAL) can be used as an anatomical landmark to reliably orient the cup in primary total hip arthroplasty and compare it to acetabular cups placed with the help of mechanical angle guide (MAG) device.

MATERIALS AND METHODS

Thirty Five patients with primary total hip arthroplasty, all performed by the same surgeon were included in the study. All patients had undergone surgery by anterolateral approach and all were cementless total hip arthroplasty. TAL was used as a reference guide for positioning of the cup in one group while MAG device was used in the other. Post operatively CT was done to confirm the version and inclination of the acetabular cup and the femoral stem version. SPSS was used for statistical analysis.

RESULTS

18 males and 17 females were included. The most common etiological cause for THR was secondary osteoarthritis due to AVN (40%). At 18 months follow up, there was just 1 case of dislocation in group in which angle guide device was used. The mean anteversion of the acetabular cup on CT findings was 23.82° by using TAL while 18.35° with help of MAG device (P < 0.05). All were within Leweniks safe zone.

CONCLUSIONS

The TAL and MAG device both can be effectively used to align the acetabulum component. TAL is patient specific intraoperative landmark which is not affected by patient positioning while angle guide device can give false positive assessment of cup version.

Personalized Cup Positioning Guides Improved Cup Positioning and Hip Ranges of Motion in Robotic Assisted Total Hip Arthroplasty

Objective

Precise hip cup positioning is essential for the prevention of component impingement and dislocation in robotic assisted total hip arthroplasty (THA). Currently, the robotic system uses a mechanical alignment guide (MAG) for cup placement, which is one-size-fits-all, and the optimal cup positioning is controversial. Robotic assisted THA has not used any personalized cup positioning guides. The goal of this study was to identify an optimal guide for cup placement in robotic assisted THA to improve prognosis and life quality after THA.

Materials and Methods

Pelvis and femoral CT data of 47 participants were retrospectively collected for preoperative planning of robotic THA. The universal MAG guide and three personalized guides, including acetabular rim labrum guide (ARLG), transverse acetabular ligament guide (TALG), and ischiatic-pubis line guide (IPLG), were used to pose cups in the acetabulum of each participant. The position of cups was evaluated by inclination and anteversion; the function of hip joints was evaluated by hip ranges of motion, including abduction, adduction, extension, flexion, internal rotation, and external rotation.

Results

In terms of cup positioning, ARLG provided a bigger cup inclination (p < 0.0001), while IPLG and TALG provided smaller cup inclination (p < 0.001) than MAG; the three personalized guides provided larger cup anteversion (p < 0.0001) than MAG. In terms of HROMs, compared with the use of MAG, the use of three personalized guides significantly decreased abduction (p < 0.0001), extension (p < 0.0001), and external rotation (p < 0.0001), but increased significantly flexion (p < 0.0001) and internal rotation (p < 0.0001); the use of ARLG significantly reduced adduction (p < 0.0001), but the use of IPLG and TALG increased adduction (p < 0.0001).

Conclusion

Compared with MAG, personalized guides provided greater flexion and internal rotation, which may reduce the risk of posterior dislocation. Among the three personalized guides, IPLG is the most reliable one for the preoperative planning of robotic assisted THA.

Analysis of four methods of measuring three-dimensional pelvic tilt in the lateral decubitus position

Proper alignment of acetabular implantation is necessary for good patient outcomes and preventing complications or additional surgeries in total hip arthroplasty (THA). Rotation of the pelvis in lateral decubitus (LD) is typically not accounted for as surgeons use the surgery table as a reference plane to align implants. This study compared four techniques to measure 3D pelvic rotations in LD position using computer models. CT scans of 19 subjects in LD position were used to create 3D pelvis models. Pelvic rotations were measured by three users using four techniques: landmark (LM), defined plane (DP), anterior pelvic plane (APP), and plane of best symmetry (POBS) methods. Measurements were analysed for intra-user reliability and relationships between methods were assessed using intraclass correlation coefficient, standard error of measurement, and coefficient of determination. The POBS method exhibited the highest inter-observer reliability and is recommended as a new measurement technique to measure pelvic rotations before THA surgery. The LM method exhibited low reliability but may be suitable for expert users familiar with pelvic landmarks. The APP method should only be used when the patients' APP planes are known in neutral standing and side-lying postures. The DP method is not recommended due to substantial individual variability. Graphical abstract.

Does difference in stem design affect accuracy of stem alignment in total hip arthroplasty with a CT-based navigation system?

The efficacy of a computed tomography (CT)-based navigation system to accurately position the stem for intended alignment is unclear. In addition, the influence of stem design on the accuracy of insertion is unknown. We therefore retrospectively compared the accuracy and precision for the intended alignment of two different designs of femoral stem which were implanted with or without the navigation system. Forty-nine total hip arthroplasties (THAs) using a tapered wedge stem and 91 THAs using an anatomic stem were evaluated for the navigation group. Thirty-three THAs using the tapered wedge stem and 15 THAs using the anatomic stem were controls for the non-navigation group. Differences between postoperative measurement and preoperative planning were compared among the groups. In the navigation groups, accuracy (mean absolute difference) and precision (95% limits of agreement) of stem anteversion were 4.3° and ± 10.1° in the tapered wedge stem and 3.1° and ± 6.9° in the anatomic stem. In the non-navigation groups, these were 6.0° and ± 15.2° and 4.8° and ± 12.4°, respectively. The accuracy and precision in the navigation groups were significantly superior to those in the non-navigation group, and those in the anatomic stem group were significantly superior to those in the tapered wedge group. Using the CT-based navigation system, the accuracy and precision for intended stem anteversion were improved. When compared under guidance of navigation system, the accuracy and precision for intended stem anteversion in the anatomic stem were superior to those in the tapered wedge stem.

Total Hip Arthroplasty Using Imageless Computer-Assisted Navigation-2-Year Follow-Up of a Prospective Randomized Study

The purpose of this study is to compare computer-assisted to manual implantation-techniques in total hip arthroplasty (THA) and to find out if the computer-assisted surgery is able to improve the clinical and functional results and reduce the dislocation rate in short-terms after THA. We performed a concise minimum 2-year follow-up of the patient cohort of a prospective randomized study published in 2014 and evaluated if the higher implantation accuracy in the navigated group can be seen as an important determinant of success in total hip arthroplasty. Although a significant difference was found in mean postoperative acetabular component anteversion and in the outliers regarding inclination and anteversion (p < 0.05) between the computer-assisted and the manual-placed group, we could not find significant differences regarding clinical outcome or revision rates at 2-years follow-up. The implantation accuracy in the navigated group can be regarded as an important determinant of success in THA, although no significant differences in clinical outcome could be detected at short-term follow-up. Therefore, further long-term follow-up of our patient group is needed.

A simple angle-measuring instrument for measuring cemented stem anteversion during total hip arthroplasty

Background

During total hip arthroplasty (THA), the accurate placement of the femoral components is an important determinant of the success of the procedure. This study assessed the accuracy of cemented stem placement using a new angle-measuring instrument. The primary objective was to investigate the accuracy of the intraoperative measurements of cemented stem anteversion obtained using the angle-measuring instrument. Our secondary objective was to evaluate the accuracy of stem positioning performed using the angle-measuring instrument.

Methods

We compared the intraoperative stem anteversion measurements obtained using the angle-measuring instrument with postoperative stem anteversion measurements obtained using computed tomography in 149 hips (measurement accuracy). We also compared the target angle and postoperative stem anteversion in 105 hips (implantation accuracy).

Results

The mean amount of intraoperative stem anteversion was 37.9° ± 10.1°, and the mean amount of postoperative stem anteversion was 37.0° ± 10.4°. The mean measurement accuracy was 0.9° ± 6.1°, and the absolute measurement accuracy was 4.9° ± 3.7°. The correlation coefficient for the relationship between the intraoperative and postoperative stem anteversion measurements was 0.824 (p = 0.000). The mean amount of target angle was 37.4° ± 7.6°, and the mean amount of postoperative stem anteversion was 35.9° ± 9.1°. The mean implantation accuracy was 1.4° ± 5.6°, and the mean absolute implantation accuracy was 4.3° ± 3.6°. The correlation coefficient for the relationship between the target angle and postoperative stem anteversion was 0.795 (p = 0.000).

Conclusions

The angle-measuring instrument measured intraoperative stem anteversion accurately, and cemented stem was implanted accurately during THA with the angle-measuring instrument.

Portable Accelerometer-Based Navigation System for Cup Placement of Total Hip Arthroplasty: A Prospective, Randomized, Controlled Study

BACKGROUND

Malposition of the acetabular component during total hip arthroplasty (THA) is associated with increased risk of dislocation, reduced range of motion, and accelerated wear. The purpose of this study is to compare cup positioning with a portable, accelerometer-based hip navigation system and conventional surgical technique.

METHODS

In a prospective, randomized, clinical study, cups were implanted with a portable, accelerometer-based hip navigation system (navigation group; n = 55) or conventional technique (conventional group; n = 55). THA was conducted in the lateral position and through posterior approach. The cup position was determined postoperatively on pelvic radiograph and computed tomography scans.

RESULTS

An average cup abduction of 39.2° ± 4.6° (range, 27° to 50°) and an average cup anteversion of 14.6° ± 6.1° (range, 1° to 27.5°) were found in the navigation group, and an average cup abduction of 42.9° ± 8.0° (range, 23° to 73°) and an average cup anteversion of 11.6° ± 7.7° (range, -12.1° to 25°) in the conventional group. A smaller variation in the navigation group was indicated for cup abduction (P = .001). The deviations from the target cup position were significantly lower in the navigation group (P = .001, .016). While only 37 of 55 cups in the conventional group were inside the Lewinnek safe zone, 51 of 55 cups in the navigation group were placed inside this safe zone (P = .006). The navigation procedure took a mean of 10 minutes longer than the conventional technique.

CONCLUSION

Use of the portable, accelerometer-based hip navigation system can improve cup positioning in THA.

Innovative Force-PRO device to measure force and implant position in total hip arthroplasty

Total hip arthroplasty (THA) is the appropriate treatment for hip pain, dislocation, and dysfunction. THA refers to surgery to replace a hip implant, which is an effective way to recover normal hip function. The design of an implant imitates hip functions and allows bone growth in the implant area. However, it should be noted that the implant can dislocate after surgery. The main factor that should be considered during surgery is the correct position of the implant component. The acetabular cup of the hip implant should be positioned at [Formula: see text] anteversion and [Formula: see text] inclination. The evaluation of the implant inclination and anteversion during the operation decrease the risk of the implant dislocation after surgery. Developing a new innovative Force-PRO device can aid the doctor in evaluating the force on the surface of the acetabular liner and the angle of the acetabular liner during the hip implant operation. This device consists of two main sensors-force sensors and inertial measurement unit sensors. Furthermore, the 3D printings of an implant's parts should be specifically designed to integrate with these sensors. To develop the graphical user interface application, C[Formula: see text] should be the programming language of use. The graphical user interface application communicates between the device and user via a wireless communication system. CT-based imaging and force gauge measurement are the methods to evaluate the efficiency of this device. For this purpose, the sterile method is considered.

Recent Trends, Technical Concepts and Components of Computer-Assisted Orthopedic Surgery Systems: A Comprehensive Review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.

Is the alignment guide technique in total hip arthroplasty sufficient for accurate cup positioning with a modified Watson Jones approach?

PURPOSE:

Cup setting with only an alignment guide has been reported to be inaccurate in the lateral decubitus position in total hip arthroplasty (THA). We assessed the accuracy of cup positioning using only the alignment guide technique via a modified Watson Jones approach in the lateral decubitus position.

METHODS:

Two hundred hips of 189 patients underwent THA from October 2014 to September 2016 via a modified Watson Jones approach. In the final sample, 181 hips of 171 patients (35 males, 136 females) were included in this investigation. The alignment of the cup was evaluated by an anteroposterior radiograph of the pelvis 1 week after surgery. Measurements were divided into safe zone determined by Callanan and Lewinnek.

RESULTS:

There were 168 (92.8%) acetabular cups that were placed within the safe zone for both inclination and anteversion based on the safe zones defined by Lewinnek, and 134 (74%) acetabular cups that were placed within the safe zone defined by Callanan. Multiple logistic analysis showed that the laterality and the addition of the confirmation method were indicators for malpositioning of combined inclination and anteversion.

CONCLUSION:

Our data suggested that even if special tools were not used in the lateral decubitus position, using only the alignment guide enabled cup positioning to be achieved with 92.8% accuracy in the Lewinnek safe zone and 74% accuracy in the Callanan safe zone. Multiple logistic analysis showed that the laterality and the addition of a confirmation alignment guide influenced the accuracy of cup positioning.