Does Robotic-Assisted Computer Navigation Affect Acetabular Cup Positioning in Total Hip Arthroplasty in the Obese Patient? A Comparison Study

Reduction in rate of implant waste associated with robotic-assisted total hip arthroplasty

Aims

Implant waste during total hip arthroplasty (THA) represents a significant cost to the USA healthcare system. While studies have explored methods to improve THA cost-effectiveness, the literature comparing the proportions of implant waste by intraoperative technology used during THA is limited. The aims of this study were to: 1) examine whether the use of enabling technologies during THA results in a smaller proportion of wasted implants compared to navigation-guided and conventional manual THA; 2) determine the proportion of wasted implants by implant type; and 3) examine the effects of surgeon experience on rates of implant waste by technology used.

Methods

We identified 104,420 implants either implanted or wasted during 18,329 primary THAs performed on 16,724 patients between January 2018 and June 2022 at our institution. THAs were separated by technology used: robotic-assisted (n = 4,171), imageless navigation (n = 6,887), and manual (n = 7,721). The primary outcome of interest was the rate of implant waste during primary THA.

Results

Robotic-assisted THA resulted in a lower proportion (1.5%) of implant waste compared to navigation-guided THA (2.0%) and manual THA (1.9%) (all p < 0.001). Both navigated and manual THA were more likely to waste acetabular shells (odds ratio (OR) 4.5 vs 3.1) and polyethylene liners (OR 2.2 vs 2.0) compared to robotic-assisted THA after adjusting for demographic and perioperative factors, such as surgeon experience (p < 0.001). While implant waste decreased with increasing experience for procedures performed manually (p < 0.001) or with navigation (p < 0.001), waste rates for robotic-assisted THA did not differ based on surgical experience.

Conclusion

Robotic-assisted THAs wasted a smaller proportion of acetabular shells and polyethylene liners than navigation-guided and manual THAs. Individual implant waste rates vary depending on the type of technology used intraoperatively. Future studies on implant waste during THA should examine reasons for non-implantation in order to better understand and develop methods for cost-saving.

Robotic-assisted total hip arthroplasty utilizing a fluoroscopy-guided system produced similar cup accuracy and precision relative to a computerized tomography-based robotic platform

Robotic assistance for total hip arthroplasty (THA) has been demonstrated to improve accuracy of acetabular cup placement relative to manual, unassisted technique. The purpose of this investigation was to compare the accuracy and precision between a fluoroscopy-based robotic total hip arthroplasty platform (FL-RTHA) and a computerized tomography-based (CT-RTHA) platform. The study included 98 consecutive FL-RTHA and 159 CT-RTHA procedures performed via direct anterior approach (DAA). All cases were performed for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Primary outcome variables included cup implantation accuracy and precision (variance). Implantation accuracy was calculated as the absolute value of the difference between pre-operative target cup angles (inclination and anteversion) and the same post-operative angles. Percentage placement in the Lewinnek safe zone was also measured for both cohorts. The FL-RTHA and CT-RTHA cohorts demonstrated a 1.2° difference in absolute values for cup inclination accuracy (4.6° ± 3.6 vs. 3.4 ± 2.7; p = 0.005), and no difference in absolute values for cup anteversion accuracy (4.7° ± 4.1 vs. 4.6 ± 3.4; p = 0.991). Cohorts demonstrated similar precision for cup inclination and anteversion placement parameters, as well as equivalent Lewinnek safe zone placement. The use of a fluoroscopy-based robotic assistance platform for primary DAA THA resulted in similar accuracy and precision of acetabular cup placement when compared to a CT-based robotic assistance system.

Robotic-assisted Total Hip Arthroplasty and Spinopelvic Parameters: A Review

Total hip arthroplasty (THA) is an effective treatment for osteoarthritis, and the popularity of the direct anterior approach has increased due to more rapid recovery and increased stability. Instability, commonly caused by component malposition, remains a significant concern. The dynamic relationship between the pelvis and lumbar spine, deemed spinopelvic motion, is considered an important factor in stability. Various parameters are used in evaluating spinopelvic motion. Understanding spinopelvic motion is critical, and executing a precise plan for positioning the implant can be difficult with manual instrumentation. Robotic and/or navigation systems have been developed in the effort to enhance THA outcomes and for implementing spinopelvic parameters. These systems can be classified into three categories: X-ray/fluoroscopy-based, imageless, and computed tomography (CT)-based. Each system has advantages and limitations. When using CT-based systems, preoperative CT scans are used to assist with preoperative planning and intraoperative execution, providing feedback on implant position and restoration of hip biomechanics within a functional safe zone developed according to each patient's specific spinopelvic parameters. Several studies have demonstrated the accuracy and reproducibility of robotic systems with regard to implant positioning and leg length discrepancy. Some studies have reported better radiographic and clinical outcomes with use of robotic-assisted THA. However, clinical outcomes comparable to those for manual THA have also been reported. Robotic systems offer advantages in terms of accuracy, precision, and potentially reduced rates of dislocation. Additional research, including conduct of randomized controlled trials, will be required in order to evaluate the long-term outcomes and cost-effectiveness of robotic-assisted THA.

Which way forward? Comparing radiological outcomes using three different surgical approaches in robotic assisted total hip arthroplasty

OBJECTIVES

To assess the accuracy and precision of acetabular component placement in robot-assisted surgery total hip arthroplasty (RAS-THA) using three different approaches.

METHODS

This study is a secondary analysis from a multicenter, randomized controlled trial comparing the Trex RS Hip 1.0 robot navigation system across different surgical approaches. It involved 145 patients treated at three Chinese medical centers from June 2021 to July 2022. Patients with end-stage joint disease were randomly assigned to either the RAS or control group. Acetabular component positioning was evaluated radiographically, and registration accuracy was measured using Root Mean Square Error (RMSE).

RESULTS

The overall RMSE was 0.72 mm (SD = 0.24 mm), indicating consistent accuracy regardless of surgical approach. Significant variations in anteversion were noted across groups (p = 0.001). Lateral RAS-THA showed enhanced precision. The RAS Direct Anterior Approach (DAA) group had the least deviation in the rotation center's horizontal distance (0.89 ± 1.14 mm, p = 0.0014) and minimal leg length discrepancy (2.41 ± 1.17 mm). The RAS DAA approach also produced more consistent results.

CONCLUSION

Robotic assistance in THA, especially via the DAA approach, enhances the accuracy and precision of acetabular component positioning. Consistent registration accuracy across various surgical approaches confirms the reliability of these methods for THA.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier is ChiCTR2100044124.

Fluoroscopy-based robotic assistance for total hip arthroplasty improves acetabular cup placement accuracy for obese patients compared to the manual, fluoroscopic- assisted technique

BACKGROUND

Patient obesity is a risk factor for poor acetabular cup positioning in total hip arthroplasty (THA).

OBJECTIVE

To assess the impact of using a novel, fluoroscopy-based robotic THA system on acetabular cup placement in obese versus non-obese patients.

METHODS

A review of 105 consecutive manual unassisted (mTHA) (47 Obese/58 Non-obese) and 102 robotic-assisted (RA-THA) (50 Obese/52 Non-obese) primary, direct anterior approach THA procedures was conducted. All cases were performed by a single surgeon, for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Obesity was defined as a Body Mass Index (BMI) ⩾ 30 kg/m2. Outcomes included acetabular cup inclination and anteversion, and the proportion of cups within the Lewinnek safe-zone.

RESULTS

Obese patients in the mTHA cohort had larger cup inclination angles on average compared to non-obese patients (44.82∘± 6.51 vs. 41.39∘± 6.75; p= 0.009). Obese mTHA patients were less likely to have cup placement within the Lewinnek zone compared to non-obese mTHA patients (0.48 vs. 0.67; p= 0.027). Obesity had no effect on the accuracy of RA-THA.

CONCLUSION

Obesity affects the placement of the acetabular component in manual THA. The novel, fluoroscopy-based robotic THA system in this study demonstrated accurate cup placement regardless of obesity status.

Lower 90-day inpatient readmission and 1-year reoperation in patients undergoing robotic versus manual total hip arthroplasty through an anterior approach

BACKGROUND

The value of robotic-assisted total hip arthroplasty (rTHA) has yet to be determined compared to conventional manual THA (mTHA).

OBJECTIVE

Evaluate 90-day inpatient readmission rates, rates of reoperation, and clinically significant improvement of patient-reported outcome measures (PROMs) at 1-year in a cohort of patients who underwent mTHA or rTHA through a direct anterior (DA) approach.

METHODS

A single-surgeon, prospective institutional cohort of 362 patients who underwent primary THA for osteoarthritis via the DA approach between February 2019 and November 2020 were included. Patient demographics, surgical time, discharge disposition, length of stay, acetabular cup size, 90-day inpatient readmission, 1-year reoperation, and 1-year PROMs were collected for 148 manual and 214 robotic THAs, respectively.

RESULTS

Patients undergoing rTHA had lower 90-day readmission (3.74% vs 9.46%, p= 0.04) and lower 1-year reoperation (0.93% vs 4.73% mTHA, p= 0.04). rTHA acetabular cup sizes were smaller (rTHA median 52, interquartile range [IQR] 50; 54, mTHA median 54, IQR 52; 58, p< 0.001). Surgical time was longer for rTHA (114 minutes vs 101 minutes, p< 0.001). At 1-year post-operatively, there was no difference in any of the PROMs evaluated.

CONCLUSION

Robotic THA demonstrated lower 90-day readmissions and 1-year reoperation rates than manual THA via the DA approach. PROMs were not significantly different between the two groups at one year.

CT-based, robotic-arm assisted total hip arthroplasty (Mako) through anterior approach provides improved cup placement accuracy but no difference in clinical outcomes when compared to conventional technique

BACKGROUND

With the restoration of the natural hip biomechanics, a successful total hip arthroplasty (THA) and long-term survival is pursued. Although robotic THA (rTHA) has been developed to increase accuracy of implant positioning, leg lengths and offsets, discussions about its radiological and clinical advantages over conventional THA (cTHA) continues.

OBJECTIVE

The aim of this study was to compare clinical and radiological outcomes of robotic and conventional THA.

METHODS

This retrospective study compares functional and radiological outcomes of 82 rTHA with a matched group of 82 cTHA in terms of age, sex, body mass index and preoperative functional scores. The minimum follow up was 12 months for all patients. Functional outcomes were Harris Hip Score (HHS) and the Western Ontario and McMaster University Osteoarthritis index (WOMAC) evaluated pre- and postoperatively. Radiological evaluations included position of cup placement according to Lewinnek and Callanan safe zones, Canal Fill Ratio (CFR), Leg Length Discrepancy (LLD), Lateral offset (LO) and Femoral Component Alignment (FCA). Complications were also evaluated.

RESULTS

In the rTHA group, 91.5% (75 out of 82) of the acetabular cups were positioned within the safe zone whereas it was 63.4% (52 out of 82) for the cTHA group (p< 0.001). According to Callanan, they were 84.1% and 50%, respectively (p< 0.001). Between the groups, no statistically significant difference was found in CFR, LLD, HO, FCA, AI, AA, WOMAC, HHS and major complication rates.

CONCLUSION

rTHA is superior to cTHA in terms of accuracy and reproducibility of the cup placement, however no apparent clinical benefit was found in short term follow.

Accuracy comparison of cup positioning during total hip arthroplasty using Hip Align and AR-Hip in the supine position

INTRODUCTION

The aim of this study is to compare the accuracy of acetabular cup positioning between the accelerometer-based navigation system and the augmented reality-based navigation system during THA in the supine position.

MATERIALS AND METHODS

This retrospective study included 66 patients (70 hips) who underwent THA using two types of portable navigation system, Hip Align or AR-Hip, in the spine position. The absolute difference between the intraoperative navigation record and postoperative measurement using computed tomography data was evaluated. Preoperative clinical factors that decreased the accuracy of cup positioning by ≥ 3° were analyzed via multiple logistic regression analyses.

RESULTS

The average absolute error of inclination was 2.8 ± 2.6° in Hip Align and 2.7 ± 1.8° in AR-Hip, and absolute anteversion error was 2.5 ± 2.0° in Hip Align and 2.6 ± 2.2° in AR-Hip, and there was no significantly different between the two navigation systems. There was a significant association between the absolute measurement error (≥ 3°) of cup inclination and patients' BMI in the Hip Align group [odds ratio (OR) 1.350; 95% confidence interval (CI) 1.035-1.760; p = 0.027], but not in the AR-Hip group.

CONCLUSIONS

The accuracy of the acetabular cup positioning between the Hip Align and AR-Hip showed no difference during THA in the spine position. The high BMI could have negative influence on the accuracy of cup positioning in THA using Hip Align, thus AR-Hip could be designable for obesity patients.

A review of robotic-assisted total hip arthroplasty

Total hip arthroplasty (THA) is a successful surgical method for hip replacement but still poses challenges and risks. Robotic-assisted THA (rTHA) using new generation robotic systems has emerged to improve surgical precision and outcomes. The purpose of this paper is to review the literature on rTHA, with a focus on its advantages, such as individualized preoperative planning, intraoperative assistance, and improved accuracy in implantation, especially in complex cases. Additionally, it aims to explore the disadvantages associated with the use of rTHA, including high costs, the learning curve, and prolonged operation time compared to manual THA (mTHA), which are critical drawbacks that require careful consideration and efforts for minimization. Some financial analyses suggest that rTHA may offer cost-effectiveness and reduced postoperative costs compared to mTHA. While technological advancements are expected to reduce technical complications, there are still debates surrounding long-term outcomes. Practical limitations, such as limited availability and accessibility, also warrant attention. Although the development of rTHA shows promise, it is still in its early stages, necessitating critical evaluation and further research to ensure optimal patient benefits.

Total Hip Arthroplasty: An Update on Navigation, Robotics, and Contemporary Advancements

While total hip arthroplasty (THA) remains effective for improvement of pain and function in patients with osteoarthritis and avascular necrosis, there remain areas of continued pursuit of excellence, including decreasing rates of dislocation, leg length discrepancy, implant loosening, and infection. This review article covers several bearing surfaces and articulations, computer-assisted navigation and robotic technology, and minimally invasive surgical approaches that have sought to improve such outcomes. Perhaps the most significant improvement to THA implant longevity has been the broad adoption of highly cross-linked polyethylene, with low wear rates. Similarly, navigation and robotic technology has proven to more reproducibly achieve intraoperative component positioning, which has demonstrated clinical benefit with decreased risk of dislocation in a number of studies. Given the projected increase in THA over the coming decades, continued investigation of effective incorporation of technology, soft tissue-sparing approaches, and durable implants is imperative to continued pursuit of improved outcomes in THA.

Does acetabular robotic-assisted total hip arthroplasty with femoral navigation improve clinical outcomes at 1-year post-operative? A case-matched propensity score study comparing 98 robotic-assisted versus 98 manual implantation hip arthroplasties

INTRODUCTION

Despite the optimization of implant positioning, the clinical benefit of the use of robotic assistance during THA remains uncertain. In this case-control study (robotic versus manual technique) we made a retrospective short-term comparison of: (1) the functional results, (2) the complications, (3) and the influence of radiological symmetrization of the hips on the functional result.

HYPOTHESIS

The use of a robotic arm improved the functional results of a THA.

MATERIALS AND METHOD

A retrospective case-control study was performed, including patients with unilateral hip osteoarthritis who underwent a robotic arm-assisted THA (THA-R). The controls (THA-C) were matched according to age, sex, body mass index and surgical approach. The Harris (HHS), Oxford (OHS) and Forgotten Joint (FJS) scores were collected preoperatively and 1 year postoperatively. At each review, complications were categorized into minor events, revision surgery with and without implant change. Radiographic analysis was performed on weight-bearing images of the pelvis 3 months postoperatively. The objective of the surgery was symmetrization of the THA in the contralateral healthy hip. For each measured parameter of the hip joint center of rotation (COR), global offset (GO) and articular leg length discrepancy (aLLD), the difference between the two sides corresponding to the delta symmetrization was compared.

RESULTS

Ninety-eight patients were included in the THA-R group and matched to 98 controls in the THA-C group. At 1 year postoperatively, the FJS and OHS scores were statistically higher in the THA-R group, respectively 82.1±22.3 [8.3; 100] and 40.8±8.8 [6; 48] vs. 71.2±27.8 [0; 100] and 38.1±9.7 [12; 48] in the THA-C group (p=0.004 and p=0.043). There was no difference in HHS (THA-R: 85.9±15.8 [31; 100] vs. THA-C: 85.8±13.3 [49-100] (p=0.962)). The implant revision rate at 1 year was significantly higher in the THA-C group (0% vs. 5.1% (p=0.025)). There was no difference in the reoperation without component exchange despite 3 dislocations (3.1%) in the THA-R group (5 (5.1%) vs. 9 (9.2%) (p=0.273)). The rate of abarticular pathologies (ilio-psoas irritation and greater trochanteric bursitis) was higher in the THA-C group (10 (10.8%) vs. 2 (2%) (p=0.016). Robotic acetabular assistance allowed a significantly better restitution of the horizontal position (THA-R: 1mm±4.8 [-11.7; 12.6] vs. THA-C: 4.1mm±7 [-29.6; 28] (p=0.0005)) and vertical COR (THA-R: 0.5mm±3.1 [-6; 8.3] vs. THA-C: 2mm±4.1 [-6; 14.6] (p=0.0068)). Navigated assistance of the femur did not significantly optimize the restitution of the Global Offset (THA-R: +2mm±6.4 [-16.4; 27.6] vs. THA-C: +0.5mm±7 .7 [-34; 30.2] (p=0.145)), or lower limb length (THA-R: +1.1mm±5 [-8.2; 13.5] vs. THA-C: +0.3mm±6 [-14.1; 22.5] (p=0.344). The FJS was statistically correlated with the restoration of the symmetry of the COR and the aLLD. A post-hoc power analysis confirmed sufficient potency (1-β=0.85).

CONCLUSION

Robotic acetabular assistance combined with femoral navigation improves clinical outcomes of THAs with fewer short-term complications. The precision of the positioning of the implants, optimized by the computer-assisted surgery system, is correlated with the missed joint score.

LEVEL OF EVIDENCE

III, retrospective case-control study.

The Safety and Efficacy of the Anterior Approach Total Hip Arthroplasty as per Body Mass Index

BACKGROUND

Obesity is associated with component malpositioning and increased revision risk after total hip arthroplasty (THA). With anterior approaches (AAs) becoming increasingly popular, the goal of this study was to assess whether clinical outcome post-AA-THA is affected by body mass index (BMI).

METHODS

This multicenter, multisurgeon, consecutive case series used a prospective database of 1,784 AA-THAs (1,597 patients) through bikini (n = 1,172) or standard (n = 612) incisions. Mean age was 63 years (range, 20-94 years) and there were 57.5% women, who had a mean follow-up of 2.7 years (range, 2.0-4.1 years). Patients were classified into the following BMI groups: normal (BMI < 25.0; n = 572); overweight (BMI: 25.0-29.9; n = 739); obese (BMI: 30.0-34.9; n = 330); and severely obese (BMI ≥ 35.0; n = 143). Outcomes evaluated included hip reconstruction (inclination/anteversion and leg-length, complications, and revision rates) and patient-reported outcomes including Oxford Hip Scores (OHS).

RESULTS

Mean postoperative leg-length difference was 2.0 mm (range: -17.5 to 39.0) with a mean cup inclination of 34.8° (range, 14.0-58.0°) and anteversion of 20.3° (range, 8.0-38.6°). Radiographic measurements were similar between BMI groups (P = .1-.7). Complication and revision rates were 2.5% and 1.7%, respectively. The most common complications were fracture (0.7%), periprosthetic joint infection (PJI) (0.5%), and dislocation (0.5%). There was no difference in dislocation (P = .885) or fracture rates (P = .588) between BMI groups. There was a higher rate of wound complications (1.8%; P = .053) and PJIs (2.1%; P = .029) among obese and severely obese patients. Wound complications were less common among obese patients with the 'bikini' incision (odds ratio 2.7). Preoperative OHS was worse among the severely obese (P < .001), which showed similar improvements (Change in OHS; P = .144).

CONCLUSION

AA-THA is a credible option for obese patients, with low dislocation or fracture risk and excellent ability to reconstruct the hip, leading to comparable functional improvements among BMI groups. Obese patients have a higher risk of PJIs. Bikini incision for AA-THA can help minimize the risk of wound complications.

Robotics in Total Hip Arthroplasty: Current Concepts

This current concepts article reviews the literature pertaining to the use of robot-assisted systems in total hip arthroplasty (THA). The bulk of the literature is regarding the MAKO (currently the most used system worldwide) and the historic ROBODOC robotic systems. There is a paucity of literature available on other systems, with several still in pilot-phase development. Whilst the evidence shows improved radiological outcomes with robotic THA, functional outcomes are equivocal between conventional and robotic techniques. Acceptance of robotic THA worldwide is limited by its accessibility including cost, and by already exceptional results with the conventional technique. It is, however, a rapidly developing area of orthopaedic surgery. This article discusses the history of robotics in THA, current surgical techniques, functional and radiological outcomes, and ongoing avenues for development.

Accuracy and Precision of Acetabular Component Position Does Not Differ Between the Anterior and Posterior Approaches to Total Hip Arthroplasty With Robotic Assistance: A Matched-Pair Analysis

Background

Deviation from planned component placement with robot-assisted total hip arthroplasty (RA-THA) may differ based on surgical approach. The purpose of this study was to compare radiographic accuracy and precision of acetabular component position using RA-THA with the direct anterior approach (DAA) or posterior approach (PA).

Methods

Between 2016 and 2019, 134 PA RA-THA patients were matched to 134 DAA RA-THA patients based on age (±10 years), body mass index (±5 kg/m²), and sex (exact). Acetabular component position was assessed using (1) planned position on preoperative computed tomography, (2) intraoperative position, and (3) position on 6-week postoperative radiographs using the digital Ein Bild Röntgen Analyse system.

Results

Accuracy of acetabular component inclination in the PA cohort was lower than that in the DAA cohort (PA: 4.3° ± 2.8° vs DAA: 3.1° ± 2.4°, P = .001). Inclination precision was not statistically different (PA: 3° ± 2.4° vs DAA: 2.5° ± 1.8°, P = .071). Anteversion accuracy was not statistically different (PA: 4.1° ± 3.7° vs DAA: 3.5° ± 2.5°, P = .091). Acetabular component anteversion was more precise with DAA (PA: 4.1° ± 3.7° vs DAA: 2.9° ± 2.0°, P = .001). Radiographic outliers (anteversion or inclination was >10° or <-10° from the planned target) were significantly more prevalent in the PA cohort than in the DAA cohort (12 vs 3, P = .016).

Conclusions

The acetabular component can be positioned with excellent precision and accuracy when using RA-THA regardless of approach. Although the DAA resulted in a slight increase in precise placement of cup anteversion and more accurate placement of cup abduction with fewer outliers, these small differences may not be clinically meaningful.

Robotic arm-assisted arthroplasty: The latest developments

Joint arthroplasty is an effective method for treating end-stage joint lesions and damages. Robotic arm-assisted arthroplasty, a rapidly developing technology that combines navigation technology, minimally invasive technology, and precise control technology of the robotic arm, can achieve accurate preoperative planning, optimal selection of implants, minimally invasive surgery, precise osteotomy, and accurate placement of the artificial joint. It has the characteristics of high accuracy and stability, and thus is more and more widely used in the field of joint surgery. In this paper, we systematically reviewed the application and clinical efficacy of robotic arm-assisted technology in hip and knee arthroplasty to provide reference for its future promotion.

Comparison of Surgical Time, Short-term Adverse Events, and Implant Placement Accuracy Between Manual, Robotic-assisted, and Computer-navigated Total Hip Arthroplasty: A Network Meta-analysis of Randomized Controlled Trials

INTRODUCTION

Recent years have observed the increasing utilization of robotic-assisted and computer navigation techniques in total hip arthroplasty (THA), given the proposed benefits of enhanced consistency and precision in implant placement. The purpose of this study was to conduct a systematic review of randomized controlled trials (RCTs) to determine whether differences in surgical times, adverse events, and implant positioning existed between manual, robotic-assisted, and computer navigation THA.

METHODS

PubMed, OVID/MEDLINE, and Cochrane databases were queried for RCTs comparing robotic-assisted versus manual THA and computer navigation versus manual THA at a minimum 1-year follow-up. Frequentist model network meta-analyses with P-scores were conducted to compare revisions, complications, and surgical times among the three treatment groups. A random-effects meta-analysis between computer navigation and manual THAs was conducted to analyze cup positioning because no robotic-assisted THA studies reported this outcome.

RESULTS

Five RCTs compared robotic-assisted and manual THAs, while seven compared computer navigation and manual THAs. manual THA was associated with significantly reduced surgical time in comparison with computer navigation (mean difference: 23.3 minutes) and robotic-assisted THAs (mean difference: 8.6 minutes; P < 0.001). No difference was observed in the incidence of all-cause complications (computer navigation: 1.7%, manual: 6.6%, and robotic-assisted: 16.2%) or revisions (computer navigation: 1.0%, manual: 1.7%, and robotic-assisted 4.8%) among the three treatment groups based on the network meta-analysis. In three studies that reported acetabular implant positioning, computer navigation had a significantly higher percentage of acetabular cups placed in the Lewinnek "safe zone" compared with manual THA (79% versus 52%; P = 0.02).

CONCLUSIONS

manual THA results in markedly shorter surgical times and a similar incidence of complications and revisions compared with robotic-assisted and computer navigation THAs, given the sample sizes available for study. However, computer navigation THA led to increased precision in the placement of acetabular implants.

Does robotic-assisted computer navigation improve acetabular cup positioning in total hip arthroplasty for Crowe III/IV hip dysplasia? A propensity score case-match analysis

AIMS

Total hip arthroplasty (THA) in patients with hip-dislocation dysplasia remains challenging. This study aims to evaluate whether these patients may benefit from robotic-assisted techniques.

METHODS

We reviewed 135 THAs (108 conventional THAs and 27 robotic-assisted THAs) for Crowe type III or IV from January 2017 to August 2019 in our institution. Robotic-assisted THAs were matched with conventional THAs at a 1:1 ratio (27 hips each group) using propensity score matching. The accuracy of cup positioning and clinical outcomes were compared between groups.

RESULTS

The inclination of the cup for conventional THAs and robotic THAs was 42.1 ± 5.7 and 41.3 ± 4.6 (p = 0.574), respectively. The anteversion of the cup for conventional THAs was significantly greater than that of robotic THAs (29.5 ± 8.1 and 18.0 ± 4.6; p < 0.001), respectively. The ratio of the acetabular cup in the Lewinnek safe zone was 37% (10/27) in conventional THAs and 96.3% (26/27) in robotic THAs (p < 0.001). Robotic THAs did not achieve better leg length discrepancy than that of conventional THAs (- 0.4 ± 10.9 mm vs. 0.4 ± 8.8 mm, p = 0.774). There was no difference in Harris Hip Score and WOMAC Osteoarthritis index between groups at the 2-year follow-up. No dislocation occurred in all cases at the final follow-up.

CONCLUSION

Robotic-assisted THA for patients with high dislocation improves the accuracy of the implantation of the acetabular component with respect to safe zone.

Does robotic assisted technology improve the accuracy of acetabular component positioning in patients with DDH?

BACKGROUND

Accurate positioning of the acetabular component is key in performing total hip arthroplasty (THA). However, reconstruction of the acetabulum in the setting of developmental dysplasia of the hip (DDH) is a challenge. Robotic assisted THA has the potential to improve the accuracy of implantation of the acetabular cup in cases with DDH. The purpose of this study was to assess whether robotic technology improves the accuracy of acetabular component positioning in patients with DDH.

MATERIAL AND METHODS

We included 59 THAs using robotic assisted technology from June 2019 to January 2020 as the study group. These were compared to conventional THAs without robotic technology after control for age, gender, body mass index (BMI), Crowe type and operation date. Radiographic measurements were taken by 2 blinded orthopaedic residents. The percentage of hips within the Lewinnek and Collanan safe zones were calculated, along with acetabular rotation centers for the "target zone." Surgical time and perioperative bleeding were also compared between both groups.

RESULTS

One patient suffered dislocation in conventional group while no dislocation occurred in robotic group. The acetabular components of the robotic assisted group had more cases located within the Lewinnek (p = 0.013) and Collanan (p = 0.008) safe zones than conventional group (94.9% vs 79.7% and 74.6% vs 50.8%). There were 7 cases in conventional group and 4 cases in robotic group that had more lateral or more superior rotational centers of THA, but did not reach statistical significance (p = 0.342). No statistical difference was detected between groups with regards to blood loss (p = 0.098) and surgical time (p = 0.602).

CONCLUSION

Robot assisted technology can assist surgeons with implanting acetabular cups more in Lewinnek and Callanan safe zone than conventional techniques without additional blood loss and surgical time.

LEVEL OF EVIDENCE

Therapeutic Level Ⅲ.

Primary Robotic-Arm Assisted Total Hip Arthroplasty: An Analysis of 501 Hips With 44-Month Follow-up

The aim of this study was to report patient-reported outcome measurements in a large group of patients who underwent robotic-arm assisted primary total hip arthroplasty (THA). Prospectively collected data were retrospectively reviewed between April 2012 and May 2017. Primary THAs using the Mako robotic-arm assisted (Mako Surgical Corp [Stryker]) with minimum 2-year follow-up for Harris Hip Score (HHS) and Forgotten Joint Score-12 (FJS-12) were included. Exclusion criteria were body mass index (BMI) of 40 kg/m² or greater, age younger than 21 years, workers' compensation, or unwillingness to participate. Visual analog scale (VAS) score for pain and patient satisfaction score were obtained. Intraoperative measurements for leg length, global offset, acetabular inclination, and version were documented. A total of 501 hips were included, with 57.29% of the patients being female. Mean follow-up was 43.99±15.59 months. Mean age was 58.70±9.41 years. Mean BMI was 28.41±4.55 kg/m². Mean HHS was 90.87±13.45, mean FJS-12 was 79.97±25.87, mean VAS score was 1.20±2.06, and mean patient satisfaction score was 8.85±2.08. Intraoperative values for acetabular inclination and version were 40.0°±2.2° and 20.5°±2.4°, respectively. The rate of revision due to instability was 0.2%. Patients who received primary robotic-arm assisted THA reported excellent results at 44-month follow-up for multiple patient-reported outcome measurements. Consistency in acetabular cup placement accuracy was achieved regarding the Lewinnek and Callanan safe zones. [Orthopedics. 2021;44(2):70-76.].

Short-term Clinical Outcomes of Robotic-Arm Assisted Total Hip Arthroplasty: A Pair-Matched Controlled Study

Advances have made robotic assistance a viable option in total hip arthroplasty (THA). However, the clinical outcomes of this procedure relative to manual THA are limited in the literature. This study compared robotic-arm assisted (RAA) THA and manual THA at minimum 2-year follow-up. Data were collected prospectively on all THAs performed from July 2011 to January 2015. Patients were included if they underwent RAA primary THA for idiopathic osteo-arthritis and had minimum follow-up of 2 years. The following patient-reported outcomes were compared: Harris Hip Score (HHS), Forgotten Joint Score (FJS-12), visual analog scale (VAS) pain score, and satisfaction. Postoperative radio-graphs were analyzed for cup inclination, cup version, leg-length discrepancy, and global offset. Robotic-arm assisted THA patients were matched 1:1 with manual THA patients for age, sex, body mass index, and surgical approach. Each study group included 85 patients. There were no significant differences in the demographic factors between the groups. Both HHS and FJS-12 were significantly higher in the RAA group at minimum 2-year follow-up. The VAS score was lower in the RAA group, but this difference was not statistically significant. A significantly higher proportion of patients were in the Lewinnek and Callanan safe zones for cup orientation. There was no difference between the groups in patient satisfaction. Robotic-arm assisted THA yielded improved short-term patient outcomes compared with manual THA and higher likelihood of cup placement in the safe zones. No differences were found regarding VAS scores, patient satisfaction, complication rates, or subsequent revisions between groups. [Orthopedics. 2021;44(2):e236-e242.].

Comparison of Outcomes After Robotic-Assisted or Conventional Total Hip Arthroplasty at a Minimum 2-Year Follow-up: A Systematic Review

BACKGROUND

This systematic review aimed to present an updated analysis of the evidence comparing outcomes between robotic-assisted total hip arthroplasty (robotic THA) and conventional manual total hip arthroplasty (manual THA).

METHODS

A PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) systematic review was performed using the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, PubMed, MEDLINE, and Embase. Controlled studies comparing primary robotic THA and manual THA utilizing patient-reported outcome measures (PROMs) at a minimum follow-up of 2 years were included. We also compared radiographic outcomes, dislocation rates, and revision surgical procedures between groups. The ROBINS-I (Risk of Bias in Non-Randomized Studies - of Interventions) and Cochrane Risk of Bias 2.0 tools were used to assess study quality and risk of bias.

RESULTS

Of 765 studies identified, 7 articles comparing robotic THA with manual THA met inclusion criteria. A total of 658 patients were assessed, 335 of whom underwent robotic THA. The majority of studies found no significant differences (p > 0.05) in PROMs between the 2 techniques. Two low-quality studies (Level III) found significantly better postoperative PROMs favoring robotic THA at 2 years. When assessing radiographic outcomes, 6 studies showed that robotic THA resulted in more consistent and accurate component placement. No differences in postoperative dislocations, complications, or revision rates were found between groups except in 1 study, which found significantly more dislocations and revisions in the robotic THA cohort. Reported operative times were a mean of 12 to 25 minutes longer when using robotic THA.

CONCLUSIONS

The existing literature comparing robotic THA and manual THA is scarce and low-quality, with findings limited by methodological flaws in study design. Although evidence exists to support increased accuracy and reproducibility of THA component placement with robotic THA, this has not been shown to reduce postoperative dislocation and revision rates. Based on the available evidence, functional outcomes are comparable between techniques, and robotic THA appears to be associated with longer operative times. To fully evaluate the utility of robotic THA, additional well-designed, prospective controlled studies with continuous long-term monitoring are required.

LEVEL OF EVIDENCE

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

Adoption of Robotic Arm-Assisted Total Hip Arthroplasty Results in Reliable Clinical and Radiographic Outcomes at Minimum Two-Year Follow Up

INTRODUCTION

Longevity and success of total hip arthroplasty (THA) is largely dependent on component positioning. While use of robotic platforms can improve this positioning, published evidence on its clinical benefits is limited. Therefore, the aim of this study was to assess the clinical outcomes of THA with robotic surgical assistance.

MATERIALS AND METHODS

We conducted an analysis of robotic arm-assisted primary THAs performed by a single surgeon utilizing a posterior approach. A total of 99 patients (107 cases) who had a minimum two-year follow up were identified. Their mean age was 61 years (range, 33 to 84 years), and their mean body mass index was 30.5 kg/m2 (range, 18.5 to 49.1 kg/m2). There were 56% female patients and primary osteoarthritis was the principal hip diagnosis in 88.8%. Operative times, lengths of hospital stay, and discharge dispositions were recorded, along with any complications. Modified Harris Hip Scores (HHS) were calculated to quantify clinical outcomes.

RESULTS

Mean postoperative increases in HHS at 2- to 5.7-year follow up was 33 points (range, 6 to 77 points). There were no complications attributable to the use of robotic assistance. Surgical-site complications were rare; one case underwent a revision for prosthetic joint infection (0.93%) but there were no dislocations, periprosthetic fractures, or cases of mechanical implant loosening. There was no evidence of progressive radiolucencies or radiographic failure.

DISCUSSION

Robotic arm-assisted THA resulted in low complication rates at minimum two-year follow up, with clinical outcomes comparable to those reported with manual surgery.1-4 The haptically-guided acetabular bone preparation enabled reliable cementless acetabular fixation and there were no adverse events related to the use of the robot. Dislocations were avoided in this case series. Randomized controlled clinical trials are needed to compare manual to robotic surgery and to investigate whether the precision found with this functional planning will reliably reduce the incidence of dislocations.

Accuracy of cup position following robot-assisted total hip arthroplasty may be associated with surgical approach and pelvic tilt

This study aimed to investigate the accuracy of cup placement and determine the predictive risk factors for inaccurate cup positioning in robot-assisted total hip arthroplasty (THA). We retrospectively analyzed 115 patients who underwent robot-assisted THA between August 2018 and November 2019. Acetabular cup alignment and three-dimensional (3D) position were measured using pre- or postoperative computed tomography (CT) data. Absolute differences in cup inclination, anteversion, and 3D position were assessed, and their relation to preoperative factors was evaluated. The average measurement of the absolute differences was 1.8° ± 2.0° (inclination) and 1.9° ± 2.3° (anteversion). The average absolute difference in the 3D cup position was 1.1 ± 1.2 mm (coronal plane) and 0.9 ± 1.0 mm (axial plane). Multivariate analysis revealed that a posterior pelvic tilt [odds ratio (OR, 1.1; 95% confidence interval (CI), 1.00–1.23] and anterior surgical approach (OR, 5.1; 95% CI, 1.69–15.38) were predictive factors for inaccurate cup positioning with robot-assisted THA. This is the first study to demonstrate the predictive risk factors (posterior pelvic tilt and anterior surgical approach) for inaccurate cup position in robot-assisted THA.

The Impact of Author Financial Conflicts on Robotic-Assisted Joint Arthroplasty Research

BACKGROUND

Recent studies have suggested clinical superiority with robotic-assisted arthroplasty compared to traditional techniques. However, concerns exist regarding the author's financial conflicts of interest (COI), which may influence research outcomes. This study aimed to determine whether COI relating to robotic-assisted arthroplasty influences the results of published outcomes following total hip (THA), total knee (TKA), and unicompartmental knee arthroplasty (UKA).

METHODS

We performed a systematic review to identify all studies evaluating the use of robotics in THA, TKA, and UKA. An author's financial COI was identified if they reported a relevant disclosure through the American Academy of Orthopedic Surgeons or within the study article. We then queried the Open Payments website to record all payments made from a robotic company in the year prior to publication. Each study was categorized as either favoring robotics (n = 42), neutral (n = 10), or favoring traditional techniques (n = 2). We then compared the number of conflicted authors, journal impact factor, level of evidence, and mean annual industry payment to each author.

RESULTS

Of the 54 studies meeting inclusion criteria, 49 (91%) had an author financial COI. Conflicted studies were more likely to report favorable results of robotics than nonconflicted studies. When compared to studies favoring conventional techniques, those demonstrating favorable robotics outcomes had a higher number of conflicted authors and a higher mean industry payment per author. There was no difference in the level of evidence or journal impact factor.

DISCUSSION

Nearly all studies comparing robotic THA, TKA, and UKA to conventional techniques involve financially conflicted authors. Further studies without COI may provide unbiased results.

Current concepts in robotic total hip arthroplasty

INTRODUCTION

Total hip replacement provides mostly fair functional and clinical results. Many factors play an essential role in hip stability and long-term outcomes. Surgical positioning remains fundamental for obtaining accurate implant fit and prevent hip dislocation or impingement. Different categories of robotic assistance have been established throughout the previous years and all of the technologies target accuracy and reliability to reduce complications, and enhance clinical outcomes.

MATERIALS AND METHODS

An overview is proposed over the principles of robotic assistance in hip arthroplasty surgery. Accuracy, reliability, management of the bone stock, clinical outcomes, constraints and limits of this technology are reported, based on recent literature.

RESULTS

Potential advantages regarding pre-operative planning accuracy, cup positioning, maintenance of the center of rotation, preservation of an adequate bone stock nay clinical short- and mid-term outcomes are balanced with some reported disadvantages and limits like hip anatomical specificity, cost-effectiveness, engineering dependence.

DISCUSSION

The use of robotic-assisted THA presents clear and evident benefits related to accurate implant positioning and maintenance of a minimal bone while allowing. For some authors, an early improvement in functional results and patient's recovery. This technology demonstrated a shorter surgical time and a short learning curve required to optimize its use and this technology presents promising outcomes and results and potential use in routine clinical application but its limitation of use is still present especially the cost of the robot, the need for the presence of an engineer during the surgery, its availability of use in all hospitals as well as the difficulty presented in dysplastic or dysmorphic hip joints.

Minimum 5-Year Outcomes of Robotic-assisted Primary Total Hip Arthroplasty With a Nested Comparison Against Manual Primary Total Hip Arthroplasty: A Propensity Score-Matched Study

BACKGROUND

Robotic-assisted technology has been a reliable tool in enhancing precision and accuracy of cup placement in total hip arthroplasty (THA). Still, questions remain on the clinical benefit of this technology.

METHODS

The purposes of the ongoing study were (1) to report on minimum 5-year outcomes in patients who underwent robotic-assisted primary THA (rTHA), (2) to compare those outcomes to a propensity score-matched manual primary THA (mTHA) control group, and (3) to compare radiographic measures between the groups regarding acetabular cup placement. Prospectively collected patient data were retrospectively reviewed for primary THA recipients during June 2008 to July 2013. Patients with minimum 5-year follow-up for Harris Hip Score, Forgotten Joint Score-12, Veterans RAND-12 Mental, Veterans RAND-12 Physical, 12-Item Short Form Survey Mental, 12-Item Short Form Survey Physical, visual analog scale, and satisfaction were included. Patient-reported outcomes, cup placement, and revision rate of the rTHA group were compared with those of a propensity score-matched mTHA control group.

RESULTS

Sixty-six rTHAs were matched to 66 mTHAs. The rTHA group reported significantly higher Harris Hip Score, Forgotten Joint Score-12, Veterans RAND-12 Physical, and 12-Item Short Form Survey Physical (P < 0.001, P = 0.002, P = 0.002, P = 0.001). The acetabular implant placement by rTHA had a 9 and 4.7-fold reduced risk of placement outside the Lewinnek and Callanan safe zones, respectively (relative risk, 0.11 [95% confidence interval, 0.03 to 0.46]; P = 0.002; relative risk, 0.21 [95% confidence interval, 0.01 to 0.47]; P = 0.001). In addition, rTHA recipients had lesser absolute values of leg length discrepancy and global offset (P = 0.091, P = 0.001).

CONCLUSIONS

Patients who received rTHA reported favorable outcomes at minimum 5-year follow-up. Furthermore, in comparison to a propensity score pair-matched mTHA group, rTHAs reported higher patient-reported outcome scores and had 89% reduced risk of acetabular implant placement beyond the Lewinnek safe zone and 79% reduced risk of placement beyond the Callanan safe zone.

LEVEL OF EVIDENCE

Level III.

Robot-Assisted Total Hip Arthroplasty for Arthrodesed Hips

Background

Conversion of arthrodesed hips to total hip arthroplasty (THA) remains technically demanding. This study aims to evaluate the safety and efficacy of robot-assisted THA in arthrodesed hips.

Methods

We retrospectively analyzed 45 ankylosing spondylitis patients with hip arthrodesis in the Chinese PLA General Hospital between August 2018 and August 2019. All surgeries were carried out by one single surgeon. The patients were followed at 3 months after surgery. Gender, body mass index, angle of hip arthrodesis, operating time, intraoperative fluoroscopic times, postoperative length of hospitalization, cup positioning, postoperative leg length discrepancy, offset discrepancy, intraoperative and postoperative complications, and postoperative Harris Hip Score were collected for all patients.

Results

Twenty-two patients (35 hips) who underwent robot-assisted THA and 23 patients (37 hips) who underwent manual THA were enrolled in this study. There were no significant differences in demographics and arthrodesed angles between the two groups. The fluoroscopic times during manual THA were significantly higher than those during robot-assisted THA (2.16±1.61 vs 0.47±0.61, respectively, p=0.000). In the robotic group, the percentage of acetabular cups within the safe zone was significantly greater than in the manual group (94.29% vs 67.56%, respectively, p=0.042). For manual THA, the anteversions were significantly different between the left and right sides (21.14±7.86 vs 16.00±6.32, respectively, p=0.042); however, no such significant difference was found in robot-assisted THA.

Conclusion

Compared with manual THA for arthrodesed hips, robot-assisted THA had significant advantages in improving the frequency of achieving cup positioning within the target zone with diminished radiation dose and no increase in operating time.

Robots in the Operating Room During Hip and Knee Arthroplasty

PURPOSE OF THE REVIEW

The utilization of technology has increased over the last decade across all surgical specialties. Robotic-assisted surgery, among the most advanced surgical technology, applied to hip and knee arthroplasty has experienced rapid growth in utilization, surgical applications, and robotic platforms. The goal of this study is to provide a comprehensive review of the most commonly utilized robotic platforms for hip and knee arthroplasty and the most up to date literature on the benefits and limitations of robotic arthroplasty.

RECENT FINDINGS

Studies consistently demonstrate that that robotic-assisted surgery during total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA) improves component position and alignment. There is also growing evidence that robotic-assisted UKA improves clinical outcomes and implant survivorship and, therefore, may be cost-effective. However, there remains to be convincing evidence that robotic-assisted arthroplasty improves clinical outcome measures or reduces revision rates for THA and TKA. Potential disadvantages of robotic arthroplasty remain, including a learning curve, potential for additional radiation exposure preoperatively, and the financial costs. Robotic hip and knee arthroplasty remains attactive as studies show that it consistently improves implant position and alignment over conventional techniques. There is growing evidence that robotic UKA may improve patient outcomes and reduce revision rates, but further study is needed. In addition, further and longer-term studies are needed to determine if improved component position and alignment in TKA and THA leads to improved clinical outcomes and reduced revision rates.

Use of Robotic-Arm Assisted Technique in Complex Primary Total Hip Arthroplasty

Background

There is a lack of data concerning the use of robotic devices in more complex total hip arthroplasty (THA) cases, such as hip dysplasia, ankylosing spondylolysis, and post‐traumatic arthritis.

Case Presentation

This case study presented three cases in which the Mako robotic device was used to help accurately implement the surgical plan. The operations went smoothly. The position and angle of the acetabular shells were placed as planned without any complications related to the operation. Postoperative Harris Hip Scores were good in two patients and poor in the patient with ankylosing spondylitis. Robotic‐arm assisted surgery may be considered for complex THA cases in order to optimize the accuracy of the reconstruction, especially in the absence of conventional boney landmarks.

Current topics in robotic-assisted total hip arthroplasty: a review

Total hip arthroplasty (THA) is among the most successful procedures of modern medicine, yet failures and complications continue to occur, leaving room for improvement. Robotics is a cutting-edge technology that tries to improve joint arthroplasty surgery. There is some evidence that shows that robotic-assisted THA improves implant positioning, but less is known about its effect on clinical outcomes or the rate of complications. This article reviews the literature on robotic-assisted THA to elucidate the history, advantages, disadvantages, and current clinical understanding of this procedure.

Computer Navigation vs Conventional Total Hip Arthroplasty: A Medicare Database Analysis

BACKGROUND

Computer-assisted surgery (CAS) is applied to total hip arthroplasty (THA) in an attempt to optimize implant positioning. The effect of CAS on postoperative complications after THA remains unknown. Our study aims to assess the change in complication rates when CAS is used in THA.

METHODS

The Medicare database was studied from 2005 to 2012. All THAs performed with CAS were identified. A total of 64,944 THAs were identified, including 5412 CAS-THAs and 59,532 conventional THAs. Medical and surgical adverse events were collected at various time points.

RESULTS

CAS-THA was not associated with a decreased rate of dislocation at 30 days (1.0% vs 1.2%; odds ratio [OR], 1.14; P = .310), 90 days (1.1% vs 1.4%; OR, 1.23; P = .090), or 2 years (2.3% vs 2.3%; OR, 1.01; P = .931). CAS-THA was associated with a significantly higher rate of periprosthetic fracture at 30 days (0.4% vs 0.6%; OR, 1.46; P = .040) as well as revision THA at 30 days (1.0% vs 1.4%; OR, 1.43; P = .003) and 90 days (1.2% vs 1.7%; OR, 1.42; P < .002) when compared to conventional THA. CAS-THA was associated with a significantly lower rate of deep vein thrombosis and pulmonary embolism when compared to conventional THA at all time points (P < .05).

CONCLUSION

Administrative coding data fail to demonstrate any clinically significant reduction in short-term adverse events with CAS-THA. Further study is warranted to evaluate whether the purported benefits of CAS result in a reduction of the adverse events after THA.

A review of the evolution of robotic-assisted total hip arthroplasty

INTRODUCTION

Total hip arthroplasty (THA) is currently a very successful operation but continues to evolve as we try to perfect techniques and improve outcomes for our patients. Robotic hip surgery (RHS) began with the 'active' ROBODOC system in the 1980s. There were drawbacks associated with the original ROBODOC and most recently, the MAKO robot was introduced with early promising results.

AIM

The aim of this paper is to provide an up-to-date review surrounding this area and discuss the pros and cons of this technique.

METHODS

A literature review searching Medline, Embase, Ovidsp, Cochrane library, pubmed database and google scholar was performed searching keywords including: 'Robotic hip surgery', 'Robotic orthopaedic surgery', 'Computer assisted hip surgery', 'robotic arthroplasty', and 'computer assisted orthopaedic surgery'.

CONCLUSION

Robotic hip surgery aims to tackle the limitations of the human factor in surgery by promising reproducible and reliable methods of component positioning in arthroplasty surgery. However, as orthopaedic surgeons, we must critically appraise all new technology and support the use providing there is sound robust evidence backing it.

Accuracy of acetabular cup placement using CT-based navigation in total hip arthroplasty: Comparison between obese and non-obese patients

BACKGROUND

In obese patients, malpositioning of the acetabular cup increases the risk of dislocation in total hip arthroplasty (THA). The aim of this study was to determine whether obesity affects the accuracy of acetabular cup positioning using a computed tomography (CT)-based navigation system.

METHODS

We retrospectively evaluated 226 consecutive patients who underwent cementless primary THAs assisted by the CT-based hip navigation system. We divided the patients into three groups according to body mass index (BMI) and examined the difference between preoperative planning and postoperative implantation angles from CT data.

RESULTS

There was no significant correlation between BMI and both inclination and anteversion differences (R = 0.028 and R = 0.045, respectively). There were no significant differences among the BMI < 25, 25 ≦ BMI < 30, and BMI ≧ 30 groups (p value: 0.725, 0.934, respectively); between the BMI < 25 and BMI ≧ 25 groups (p value: 0.542, 0.697, respectively); and between the BMI < 30 and BMI ≧ 30 groups with regard to inclination and anteversion (p value: 0.859, 0.456, respectively). Moreover, similar findings were observed with regard to the distance between the preoperative planning and postoperative cup positioning for the transverse, anteroposterior, and craniocaudal axes of the pelvis.

CONCLUSION

We found that the accuracy of acetabular cup placement using CT based-navigation in THA was not affected in obese patients. Therefore, THAs with a CT-based navigation system are considered useful in obese patients.

Robotic-assisted compared with conventional total hip arthroplasty: systematic review and meta-analysis

BACKGROUND

Robotic-assisted total hip arthroplasty (THA) allows for accurate preoperative planning and component positioning, potentially enhancing implant survival and long-term outcomes. The relative efficacy and safety of robotic-assisted and conventional THA, however, are unclear. This systematic review and meta-analysis compared the safety and efficacy of robotic-assisted and conventional THA.

METHODS

Medline, Embase and the Cochrane Library were comprehensively searched in September 2017 to identify studies comparing the safety and efficacy of robotic-assisted and conventional THA. Seven studies were included. Data of interest were extracted and analysed using Review Manager 5.3.

RESULTS

The seven included studies involved 1516 patients, with 522 undergoing robotic-assisted and 994 undergoing conventional THA. Compared with conventional THA, robotic-assisted THA was associated with longer surgical time (not significant); lower intraoperative complication rates (OR: 0.12, 95% CI: 0.05 to 0.34, p<0.0001 I²); better cup placement, stem placement and global offset and a higher rate of heterotopic ossifications. Functional scores, limb length discrepancy and rates of revision and stress shielding were similar in the two groups. The relative amount of blood loss was unclear.

CONCLUSION

The results of this meta-analysis suggest that robotic-assisted THA has certain advantages over conventional THA, including the results of component positioning and rates of intraoperative complications. Additional comparative studies are required to determine the long-term clinical outcomes of robotic-assisted THA.

Robot-assisted total hip arthroplasty: Clinical outcomes and complication rate

BACKGROUND

The purpose of this study was to report minimum 2-year outcomes and complications for robotic-arm-assisted total hip arthroplasty (THA).

METHODS

Data were prospectively collected and retrospectively reviewed between June 2011 and April 2014. Inclusion criteria were primary robotic-arm-assisted THAs treating idiopathic osteoarthritis with ≥ 2-year follow-up. Demographics, operating time, complications, 2-year outcome scores and satisfaction, and subsequent surgeries were recorded.

RESULTS

There were 181 cases eligible for inclusion, of which 162 (89.5%) had minimum 2-year follow-up. At the latest follow-up, the mean visual analogue scale was 0.7, satisfaction was 9.3, Harris hip score was 91.1 and forgotten joint score was 83.1. Six (3.7%) intraoperative complications and six (3.7%) postoperative complications were reported. No leg length discrepancies (LLDs) or dislocations were reported.

CONCLUSIONS

Robotic-arm-assisted THA demonstrates favourable short-term outcomes and does not result in a higher complication rate compared to non-robotic THA as reported by the literature.

Robotics in trauma and orthopaedics

Recent advances and review of literature

Fluoroscopically Guided Acetabular Component Positioning: Does It Reduce the Risk of Malpositioning in Obese Patients?

BACKGROUND

Obesity has been described as an independent risk factor for acetabular component malpositioning. The purpose of this study was to determine if this could be overcome by use of fluoroscopic navigation in total hip arthroplasty (THA).

METHODS

The first, postoperative, standing, anteroposterior pelvis radiographs from 1599 consecutive patients who underwent fluoroscopic-guided THAs via anterior approach during a six-year period were obtained. We retrospectively reviewed this prospectively collected data. Inclination and anteversion were measured as described by Barrack et al. Intraoperative target ranges for inclination and anteversion angles were 30°-50° and 5°-25°. Patients were divided into 3 cohorts by body mass index, nonobese (<30 kg/m²) obese (between 30 and 40 kg/m²) and morbidly obese (>40 kg/m²), looking for significant differences in acetabular component positioning.

RESULTS

Of the 1599 patients, 1065 were nonobese, 506 obese, and 28 morbidly obese. Overall, average inclination was 37.7° and anteversion was 16.3°. Regarding inclination, 95.0% of cups were positioned in the safe zone, 95.7% for anteversion, and 91.2% for both inclination and anteversion. Analysis of each cohort individually revealed an average inclination of 37.5° in the nonobese, 37.9° in the obese, and 39.9° in the morbidly obese patients. For anteversion, each group's averages were 16.1°, 16.5°, and 16.0°, respectively. There was no significant relationship between a patient's body mass index and cup position for inclination (P = .867), anteversion (P = .673), or both inclination and anteversion (P = .624).

CONCLUSION

Fluoroscopy is a useful tool for achieving a targeted acetabular component orientation in direct anterior THA, irrespective of patient BMI.

Patient Obesity Influences Pelvic Lift During Cup Insertion in Total Hip Arthroplasty Through a Lateral Transgluteal Approach in Supine Position

BACKGROUND

Movement of the pelvis during implantation of total hip arthroplasty (THA) has a major influence on the positioning of the acetabular cup. Strong traction caused by retractors leads to iatrogenic pelvic lift and can thus be partly responsible for cup malpositioning. The objective of this study was to investigate such factors that influence pelvic lift.

METHODS

The dynamic movement of the pelvis was measured during implantation of THA in 67 patients. This was done by measuring the acceleration using the SensorLog app on a smartphone.

RESULTS

At its maximum, the pelvis was lifted by an average of 6.7°. When impacting the press-fit cup, the surgical side was raised by 4.4° compared with the time of skin incision. This lift at the time of cup implantation correlates significantly with the body mass index and the patient's abdominal and pelvic circumference.

CONCLUSION

Every surgeon performing THA must be aware of the pelvic lift during an operation. Especially in patients with a high body mass index, a large abdominal circumference, or a large pelvic circumference, there is an increased risk of malpositioning of the acetabular cup. When impacting the cup, we recommend releasing the traction of the retractor, so that the pelvis can tilt back into its natural position, and thus, the anticipated cup positioning can be implemented as exactly as possible.

What do we get from navigation in primary THA?

Navigation in primary total hip arthroplasty has a history of over 20 years. During this process, imageless computer navigation can be particularly helpful in optimally restoring the hip’s biomechanics. This involves the accurate placement of the acetabular component with the determination of the anteversion and abduction, whereby the navigated femur-first technique also allows for a calculation of the combined anteversion. Additional critical parameters such as the reconstruction of the rotation centre, as well as the femoral and acetabular offset, can also be optimally adjusted. Last but not least, an intra-operative evaluation and equalisation of the leg length is possible.

Nonetheless, the disadvantages of this surgical technique in terms of the high costs in the acquisition and preservation of the necessary devices, as well as the longer operation time, must be taken into account. However, economic aspects are not the only thing preventing widespread use of the navigation technique. Determining the plane of reference (APP) for the optimal orientation of the implants is based on palpation of the bony landmarks – and this is influenced by the thickness of the soft tissue layer. Furthermore, the experience of the surgeon constitutes a variable that influences the accuracy of navigation.

In summary, hip navigation certainly offers an interesting technique for the optimisation of total hip arthroplasty with reconstruction of proper biomechanics. At the same time, there is currently a lack of high-quality randomised controlled long-term trials that evaluate the clinical advantage for the patients, together with cost utility and survival rates.

Cite this article: Renner L, Janz V, Perka C, Wassilew GI. What do we get from navigation in primary THA? EFORT Open Rev 2016;1:205-210. 10.1302/2058-5241.1.000034.

The Evolution of Computer-Assisted Total Hip Arthroplasty and Relevant Applications

In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly.