Experience of total knee arthroplasty using a novel navigation system within the surgical field

Total knee replacement with an accelerometer-based, hand-held navigation system improves knee alignment: reliable in all patients

BACKGROUND

Achieving adequate alignment has traditionally been an important goal in total knee arthroplasty to achieve long-term implant survival. While accelerometer-based hand-held navigation systems (ABN) has been introduced as a way to achieve alignment, there is a limited body of evidence on its accuracy, especially in patients under 65 years with differing etiologies for knee arthritis. This study aimed to assess the precision of a specific ABN system in restoring the mechanical axis and report surgical variables and complications, with particular attention to younger patients.

METHODS

We conducted a retrospective review of 310 primary TKA performed with ABN from May 2016 to February 2021. The mean patient age was 67.4 (SD 8.9) years, with 43% under 65 years and mean body mass index of 33.2 (SD 6.8). The average surgical time was 96.8 min (57-171) and the average follow-up was 3.3 years (1.9-6.7). Data regarding length of stay, pain, range of motion (ROM), complications, and reinterventions were collected from the institutional joint arthroplasty registry and the medical records. Preoperative mechanical axis measurements and postoperative radiological data, including mechanical axis, component alignment and mechanical alignment outliers were analyzed.

RESULTS

The mean preoperative mechanical axis was 175.4° (SD 7.6), with 248 knees (80%) in preoperative varus. The mean postoperative mechanical axis was 179.5° (SD 1.96) with 98% of knees falling within ± 3° of the neutral mechanical axis. Only 6 knees (2 varus, 4 valgus) fell outside the ± 3° range. And 3 knees (1 varus, 2 valgus) fell outside the ± 5° range. In the sagittal plane, 296 knees (95.5%) knees were within ± 3° of goal of 3 degrees of femoral flexion and 302 (97.4%) knees were within ± 2° of goal 1° of slope for tibial component. Far outliers (alignment outside ± 5° of targeted position) were found in 3 knees. Factors such as posttraumatic arthrosis, previous surgery, presence of retained hardware, and age below 65 years were not associated with increase in alignment outliers and far outliers. No complications related to the navigation system were observed. There were 22 complications and 20 reoperations, including 2 revisions for periprosthetic joint infection and 1 revision for flexion instability. Patients that required knee manipulation achieved an ultimate flexion of 110° (SD 14.1).

CONCLUSIONS

The ABN system proved to be user-friendly and accurate in reducing alignment outliers in both coronal and sagittal planes in all patient populations. It offers a straightforward navigation solution while preserving surgeon autonomy and the use of traditional surgical tools. These findings advocate for the integration of this navigation system as a valuable tool to enhance the precision of TKA surgery in all patient groups.

Accelerometer-Based Navigation versus Conventional Total Knee Arthroplasty for Posttraumatic Knee Osteoarthritis

BACKGROUND

Posttraumatic osteoarthritis (PTOA) frequently comprises femoral or tibial deformity, which makes it difficult to perform total knee arthroplasty (TKA). Accelerometer-based navigation (ABN) could be effective in restoring a neutral mechanical axis (MA) in TKA, but a limited number of studies have been reported in association with PTOA. Therefore, we aimed to compare the lower limb MA between ABN-assisted TKA (ABN-TKA) and conventional TKA in patients with PTOA.

METHODS

We conducted a retrospective analysis of 28 PTOA patients who underwent TKA using a conventional system (cTKA group, n = 16) and the ABN system (iTKA group, n = 12). Standing long-leg radiographs were assessed for MA and prosthesis alignment as primary outcomes. A postoperative MA deviating beyond ± 3° was defined as an outlier. Perioperative outcomes, Oxford Knee Score (OKS) at 2-year follow-up, and complications were also assessed.

RESULTS

The cTKA group and the iTKA group had a mean age of 63.07 years and 65.25 years, respectively. The iTKA group had significantly better MA accuracy when compared to the cTKA group (1.60° ± 2.09° vs. 3.59° ± 1.34°, p = 0.01). The iTKA group showed significantly less MA outlier than the cTKA group (78.6% vs. 25.0%, p = 0.02). The prosthesis alignment and OKS were comparable between the groups. There were 2 periprosthetic joint infections in the cTKA group and 1 periprosthetic fracture of the distal femur in the iTKA group.

CONCLUSIONS

For PTOA of the knee, both conventional TKA and ABN-TKA significantly improved the postoperative mechanical alignment and functional outcomes. The ABN-TKA seemed to offer higher accuracy and less MA outlier when compared to conventional TKA, and thus ABN could be a good alternative option.

Can accuracy with the iASSIST navigation be confirmed by assessment? A multi-center prospective randomized controlled trial with independent three-dimensional image assessment

BACKGROUND

iASSIST is one of the novel accelerometer-based navigation systems for total knee arthroplasty (TKA). Although the accuracy of iASSIST compared with conventional instruments has been reported, such evaluations were performed on two-dimensional (2D) images (X-rays). This multi-center prospective randomized controlled trial aimed to assess component positioning between TKA with and without iASSIST by 3D image assessment, and to clarify whether the iASSIST provides any benefit with regard to alignment accuracy.

METHODS

Eighty-three knees with primary knee osteoarthritis were enrolled in this study. iASSIST was used for distal femoral and proximal tibial resection in 42 knees (iA group) and a conventional guide was used in 41 knees (CONV group). At 6 months postoperatively, component alignment was evaluated with 3D images by the independent orthopaedic surgeons, and surgical parameters, range of motion and clinical outcomes were examined.

RESULTS

The rate of knees who have the alignment within 3° of neutral compared with the iA group and CONV group were 92.9% (39/42) vs. 87.8% (36/41) for femur and 76.2% (32/42) vs. 56.1% (23/41) for tibia in the coronal plane, respectively, whereas in the sagittal plane, the rate was 85.7% (36/42) vs. 58.5% (24/41) for femur and 83.3% (35/42) vs. 78.0% (32/41) for tibia, respectively. Compared with the CONV group, the iA group had a significantly improved femoral alignment in the sagittal plane (P = 0.006). There were no clinical or patient-reported differences at 6 months postoperatively.

CONCLUSIONS

The iASSIST provides technically high accuracy in femoral resection at TKA compared with a conventional procedure.

Limb and component alignment after total knee arthroplasty comparing 28 consecutive iAssist and 28 conventional TKAs: A prospective study

BACKGROUND

The objective of this study was to assess limb and component alignment after total knee arthroplasty (TKA) on long leg X-rays and to compare the use of iAssist, an accelerometric based computer-assisted device (CAD), with conventional jigs.

METHODS

We prospectively recruited 56 consecutive patients undergoing primary unilateral TKA by a single surgeon into this study. In the first 28 patients iAssist navigation system was utilized and in the following 28 conventional jigs were used. The groups were comparable with regard to age, sex distribution, body mass index and preoperative hip-knee-ankle (HKA) angle. Our aim was to restore neutral coronal alignment and a five degree tibial slope.

RESULTS

The mean postoperative mechanical axis was 179.4° in the CAD group and 180.1° in the conventional group (P = 0.187). There were five TKAs deviating more than three degrees from neutral (18.5%) in the conventional group and none in the CAD group (P = 0.051). The mean femoral mechanical-condyles-angle was significantly closer (P < 0.001) to our target of 90° in the conventional group but contained more outliers (P = 0.67). The sagittal tibial slope was closer (P = 0.047) to our target of 85° in CAD-navigated TKAs with fewer outliers (P < 0.0001). The Oxford Knee Score showed comparable (P = 0.271) and good clinical outcome in both groups. The mean operation time was significantly longer in the CAD group (P < 0.001).

CONCLUSIONS

This study shows that the use of iAssist accelerometric CAD facilitates comparable good leg alignment after TKA in the frontal plane and more accurate tibial slope with fewer outliers in the sagittal plane compared with a conventional technique. Our operation time was longer with CAD.

The use of accelerometer-based navigation for coronal TKA alignment: a prospective, single surgeon comparative study

INTRODUCTION

There is the need for a device that can be used to accurately position components during total knee arthroplasty (TKA) with minimal impact on procedure time, workflow and cost. This study aimed to investigate the accuracy and time efficiency of a novel, accelerometer-based navigation system (ABN).

METHODS

This prospective, single surgeon study of patients undergoing TKA for osteoarthritis over a 5 year period involved a total of 138 patients: 110 using the ABN system and 28 without. The ABN system consists of two coupled inertial pods that are secured to resection guides, providing a body-fixed 3D coordinate system for limb segments. Post-operative coronal alignment was measured from standardised long-leg AP radiographs. Deviation of the femur and tibia from the neutral coronal mechanical axis was recorded. Intra-observer repeatability was performed on three independent blinded data sets. The BMI and the surgical time (skin to skin) were recorded for all patients.

RESULTS

The mean BMI was 34 in the ABN group and 33 in the control group (p = 0.92). The skin-to-skin time was also similar between the groups; 105 min in the navigation group and 100 min in the control group (p = 0.297). The use of navigation resulted in significantly fewer outliers as defined by < 3º deviation from the target angle. 3 of 110 navigated patients recorded an AP femur angle of more than 3º from the target of 90º, where 5 of 28 control patients fell outside of the ± 3º window (p = 0.009, Fig. 1).

CONCLUSION

The use of the ABN system significantly improved accuracy of implant position and alignment without increasing surgical time.

Comparison of the accelerometer-based navigation system with conventional instruments for total knee arthroplasty: a propensity score-matched analysis

Background

The accelerometer-based navigation (ABN) system is an emerging navigation system for total knee arthroplasty (TKA). This study aimed to determine whether the ABN system could improve the accuracy of mechanical alignment, component positioning, and short-term clinical outcomes for TKA when compared to conventional instruments (CON).

Methods

A total of 204 patients were selected and divided into two groups (CON: 135, ABN: 69) after applying the inclusion and exclusion criteria. Then, 1:1 propensity score matching was performed for age, gender, body mass index, hip-knee-ankle angle (HKA), Knee Society Score (KSS), Western Ontario and McMaster Universities (WOMAC) score, and follow-up times. A total of 82 consecutive patients (82 knees) underwent total knee arthroplasty using ABN (n = 41) or CON (n = 41) were enrolled in this study. The postoperative HKA, frontal femoral component (FFC) angle, frontal tibial component (FTC) angle, lateral femoral flexion (LFF) angle, and lateral tibial component (LTC) angle were compared between the two groups to evaluate mechanical alignment and component positioning. Additional clinical parameters, including haemoglobin reduction, the KSS, and the WOMAC score, were assessed at the final follow-up (the mean follow-up period was 20.9 months in the CON group and 21.2 months in the ABN group).

Results

The ABN group had a significantly improved mean absolute deviation of HKA (P = 0.033), FFC (P = 0.004), FTC (P = 0.017), LFF (P = 0.023), and LTC (P = 0.031) compared to those of the CON group. The numbers of FFCs and LTCs within 3° were significantly different (P = 0.021, P = 0.023, respectively) between the two groups. However, no differences in the numbers of FTCs within 3° (P = 0.166) and LFF within 3° (P = 0.556) were found. The ABN group had a significantly higher KS function score (P = 0.032), and the pain and stiffness scores were significantly different (P = 0.034, P = 0.020, respectively) between the two groups. Moreover, the ABN system could reduce hidden blood loss postoperatively. However, no difference was found in the KS knee score and the total WOMAC score between the two groups.

Conclusion

This study demonstrates that ABN system improved TKA mechanical alignment and component positioning and decreased the hidden blood loss postoperatively compared to conventional instruments. However, no significant differences were found in short-term clinical outcomes between ABN and conventional instruments at the final follow-up. However, whether this system contributes to revision rates and long-term clinical outcomes requires further study.

Moving object tracking in clinical scenarios: application to cardiac surgery and cerebral aneurysm clipping

BACKGROUND AND OBJECTIVES

Surgical procedures such as laparoscopic and robotic surgeries are popular since they are invasive in nature and use miniaturized surgical instruments for small incisions. Tracking of the instruments (graspers, needle drivers) and field of view from the stereoscopic camera during surgery could further help the surgeons to remain focussed and reduce the probability of committing any mistakes. Tracking is usually preferred in computerized video surveillance, traffic monitoring, military surveillance system, and vehicle navigation. Despite the numerous efforts over the last few years, object tracking still remains an open research problem, mainly due to motion blur, image noise, lack of image texture, and occlusion. Most of the existing object tracking methods are time-consuming and less accurate when the input video contains high volume of information and more number of instruments.

METHODS

This paper presents a variational framework to track the motion of moving objects in surgery videos. The key contributions are as follows: (1) A denoising method using stochastic resonance in maximal overlap discrete wavelet transform is proposed and (2) a robust energy functional based on Bhattacharyya coefficient to match the target region in the first frame of the input sequence with the subsequent frames using a similarity metric is developed. A modified affine transformation-based registration is used to estimate the motion of the features following an active contour-based segmentation method to converge the contour resulted from the registration process.

RESULTS AND CONCLUSION

The proposed method has been implemented on publicly available databases; the results are found satisfactory. Overlap index (OI) is used to evaluate the tracking performance, and the maximum OI is found to be 76% and 88% on private data and public data sequences.

Multiple instruments motion trajectory tracking in optical surgical navigation

Optical surgical navigation system has been a hot research topic because of its high accuracy. This paper focuses on identifying and tracking multiple surgical instruments to meet the requirements of applying multiple surgical instruments in clinical medicine. The methods of instrument identification based on the marker's geometrical arrangement and instrument tracking based on markers' motion vector were applied in the proposed algorithm. The experiments of multiple instruments' identification and tracking, the instruments' stability, the space distance and rotation of a pair of instruments at the same tracking time were performed to verify the proposed algorithm. The stereoscopic camera is applied to capture images, and two 850 nm filters are added in front of the binocular camera. The tracking experiment shows that ten instruments can be fully and accurately identified, and then all of them can be quickly and accurately tracked at the same time. A pair of instruments is simultaneously measured in the stability test, such as the typical surgical instrument (TSI) and the miniature surgical instrument (MSI). The ranges of standard deviations (SD) of the stability test for the TSI in the X-, Y-, and Z- axes are from 0.016 mm to 0.127 mm, from 0.011 mm to 0.090 mm, and from 0.124 mm to 0.901 mm, respectively. And the ranges of SDs for the MSI's stability test are from 0.011 mm to 0.133 mm in the X-axis, from 0.010 mm to 0.106 mm in the Y-axis, and from 0.093 mm to 0.932 mm in the Z-axis. The sub-millimeter SDs show that the proposed algorithm has a high stability. Moreover, the space distance test and the rotation test were performed for simultaneously tracking TSI and MSI. All experimental results indicate the proposed algorithm is able to meet the clinical accuracy requirements.

Current Role of Computer Navigation in Total Knee Arthroplasty

BACKGROUND

Computer-assisted surgical (CAS) navigation has been developed with the aim of improving the accuracy and precision of total knee arthroplasty (TKA) component positioning and therefore overall limb alignment. The historical goal of knee arthroplasty has been to restore the mechanical alignment of the lower limb by aligning the femoral and tibial components perpendicular to the mechanical axis of the femur and tibia. Despite over 4 decades of TKA component development and nearly 2 decades of interest in CAS, the fundamental question remains; does the alignment goal and/or the method of achieving that goal affect the outcome of the TKA in terms of patient-reported outcome measures and/or overall survivorship? The quest for reliable and reproducible achievement of the intraoperative alignment goal has been the primary motivator for the introduction, development, and refinement of CAS navigation. Numerous proprietary systems now exist, and rapid technological advancements in computer processing power are stimulating further development of robotic surgical systems. Three categories of CAS can be defined: image-based large-console navigation; imageless large-console navigation, and more recently, accelerometer-based handheld navigation systems have been developed.

CONCLUSION

A review of the current literature demonstrates that there are enough well-designed studies to conclude that both large-console CAS and handheld navigation systems improve the accuracy and precision of component alignment in TKA. However, missing from the evidence base, other than the subgroup analysis provided by the Australian Orthopaedic Association National Joint Replacement Registry, are any conclusive demonstrations of a clinical superiority in terms of improved patient-reported outcome measures and/or decreased cumulative revision rates in the long term. Few authors would argue that accuracy of alignment is a goal to ignore; therefore, in the absence of clinical evidence, many of the arguments against the use of large-console CAS navigation center on the prohibitive cost of the systems. The utilization of low-cost, handheld CAS navigation systems may therefore bridge this important gap, and over time, further clinical evidence may emerge.