The Use of Computer Navigation and Robotic Technology in Complex Total Knee Arthroplasty

Identifying Sources of Error in Computer-Navigated Total Knee Arthroplasty Using Sensitivity Analyses in Knee Models

BACKGROUND

Long-term studies comparing computer-assisted total knee arthroplasty (CA-TKA) to conventional techniques have not consistently demonstrated differences in outcomes. Errors may occur at various points of a navigated TKA, including surgeon variability in registering landmarks and when placing the cutting guide. The purpose of this study was to identify the sources of error during navigated TKA and to quantify their impact at each critical step of the procedure.

METHODS

Sawbones (n = 6) and three-dimensional (3D) printed (n = 4) knee models were stabilized on a custom wooden platform. Landmarks were digitized with the navigation system, while a 3D point capture system concurrently recorded identical points for precision assessment across multiple trials. Errors were quantified using transformation matrices (metric on SE(3)) to compare reference frames and resection planes. Sensitivity analyses using Monte Carlo simulations were performed to quantify the magnitude of specific errors in the navigation output.

RESULTS

The largest registration errors occurred at the hip center (8.2 ± 4.4 mm) and lateral tibial plateau (4.8 ± 3.7 mm), while the femur center exhibited the least variability (0.8 ± 0.5 mm). The metric on SE(3) analysis revealed that errors in femur and tibia center landmarks significantly influenced bone reference frames. No clear correlation was found between bone reference frame errors and cut plane errors. Error clouds highlighted compact femoral errors (average 1.3 mm), but broader tibial errors (average 5.8 mm). Sensitivity analyses confirmed the femur center as the most critical landmark for registration accuracy.

CONCLUSION

In computer-navigated TKA, landmarks closer to the knee joint demonstrated narrower safe zones and had the greatest impact on system accuracy. The lack of correlation between bone reference frame errors and cut plane errors suggests additional error sources. Improved intraoperative strategies, such as advanced imaging, refined algorithms, and enhanced training, are needed to optimize critical landmark registration and improve TKA outcomes.

The Influence of Preimplant Balancing on Manipulation under Anesthesia Rates following Imageless Robotic-Assisted Total Knee Arthroplasty

Acquired idiopathic stiffness (AIS) following total knee arthroplasty (TKA) often requires manipulation under anesthesia (MUA). Robotic-assisted TKA (RA-TKA) systems provide gap balance templates for objective correlation with the rate of AIS. The purpose of this study was to assess intraoperative balancing parameters that were associated with MUA utilizing an "anatomical" implant design.We performed a retrospective chart review of 265 imageless RA-TKA procedures performed by R.M. and K.D. between 2018 and 2020. The primary outcome for AIS or clinically significant "arthrofibrosis" was MUA. Patient intraoperative gap planning data were examined for association.The rate of MUA was 8.7% (23/265), which was performed at a mean follow-up time of 75.9 ± 32.2 days. The lateral to medial gap difference in extension was significantly less in patients requiring MUA (odds ratio [OR] = 0.86, 95% confidence interval [CI], 0.75-0.99) (p = 0.034). Significantly less preoperative varus mechanical axis was associated with knees requiring MUA (1.83° vs. 4.04°, OR = 1.09, 95% CI, 1.00-1.19). Decreased templated mechanical axis correction was associated with MUA (2.09° vs. 4.75°, p < 0.0001).A tighter lateral-to-medial gap in extension, less preoperative varus, and smaller templated mechanical axis corrections were associated with increased rates of MUA.

Bridging theory and practice: A comprehensive algorithm for imageless total knee arthroplasty

Total knee arthroplasty (TKA) is a surgical procedure to treat severe knee osteoarthritis. Among several techniques available for performing TKA, imageless TKA is known for achieving precise alignment while minimizing invasiveness. This work proposes a comprehensive algorithm for imageless TKA device to calculate the varus/valgus and flexion/extension angles, as well as resection depths for cutting planes at distal femur and proximal tibia. Moreover, the algorithm calculates the hip-knee-ankle (HKA) and flexion angles of the leg. Initially, the proposed algorithm was validated in a virtual environment using a CT-scanned bone model in Solidworks. Subsequently, for the real-world validation, a SoftBone model was resected with conventional intra and extramedullary rods and cross-checked with the proposed algorithm. For the third validation, another SoftBone model was resected with the proposed algorithm and cuts were measured with a vernier caliper. During this experiment, there was an error of approximately 1 mm for both femoral and tibial resection cases when using an infrared camera with an accuracy of ±0.5 mm. However, this error could be reduced using an infrared camera with higher accuracy.

The use of a modern robotic system for the treatment of severe knee deformities

BACKGROUND

Robotic-assisted total knee arthroplasty (TKA) have shown promising results in recent years with improved clinical outcomes using standard primary implants.

OBJECTIVE

The purpose of this study was to assess the experience of a single center in correcting severe coronal deformities with the use of a robotic-assisted TKA system and an increased constrained implant.

METHODS

Between July 2020 and December 2022, 30 knees in 28 patients with a major deformity and an associated ligament laxity requiring an increased constrained implant treated using an imageless robotic-assisted TKA were prospectively enrolled. Patients included in the study showed a minimum 15 degrees varus or 10 degrees valgus deviation.

RESULTS

20 cases were varus knees and 10 cases were valgus knees. Postoperative neutral alignment was defined as 0∘± 2.5∘. A CCK implant was used in 20 cases while a Constrained Posterior Stabilized implant was used in 10 cases. A neutral alignment was achieved in all patients. At a minimum 6 months follow up (f-u 6-30 months) clinical outcomes including ROM, KSS, HSS, OKS and WOMAC showed significant improvement and no major complications were registered.

CONCLUSIONS

The robotic system showed the achievement of a mechanical alignment with reliable radiographic outcomes and clinical results in the treatment of major deformities of the lower limb with the use of higher constrained implants at short term follow up. Further follow up and studies are necessary to confirm and verify these promising outcomes.

The Usefulness of a Simplified Navigation-Based Instrumentation for a Novice Surgeon in Primary Total Knee Arthroplasty: A Retrospective Analysis of a Randomized Controlled Trial

Background

A novel simplified navigation-based instrumentation system has been developed. It simplifies the existing navigation system and facilitates convenient bone cutting by positioning the tracker on an existing cutting block without additional pin fixation. This study aimed to compare the outcomes of this newly developed simplified navigation-based instrumentation system in primary total knee arthroplasty (TKA) performed by a novice surgeon with those of conventional surgical techniques.

Methods

From January 2020 to July 2020, 67 knees that underwent primary TKA using the ExactechGPS TKA Plus (group A) were compared to 68 knees that underwent primary TKA using a conventional technique (group B). All patients had a minimum follow-up of 24 months. The operative details such as tourniquet time were investigated. Postoperative hip-knee-ankle (HKA) angle and component position angles in the coronal and sagittal planes (α, β, γ, and δ angles) were evaluated. The outlier rates were compared between the groups as those lying outside ± 3°. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index for pain and function, and range of motion were compared.

Results

There was no statistically significant difference in average tourniquet time between the groups (74.3 vs. 70.3 minutes, p = 0.061). Outlier rates for HKA angle (7.5% vs. 23.5%, p = 0.010) and β angle (1.5% vs. 22.1%, p < 0.001) in group A were significantly lower than those in group B. There were no significant differences in clinical outcomes between the groups.

Conclusions

Primary TKA performed by a novice surgeon using a simplified navigation-based instrumentation system did not significantly increase the operation time, and more accurate lower extremity mechanical alignment and tibial component alignment in the coronal plane could be obtained.

Postoperative limb alignment in total knee replacement. Conventional versus navigated versus robotic techniques

BACKGROUND

Our objective was to compare the coronal mechanical axis after total knee replacement (TKR) obtained in three groups of patients subjected to conventional, navigated, and robotic surgery.

METHODS

Retrospective analysis.

RESULTS

124 knees were included (36 conventional, 41 navigated, 47 robotic). No statistically significant differences were found between the postOp tibiofemoral angle of the conventional, navigated and robotic groups (p = 0.396). A repeated-measure analysis of preOp-to-postOp also found no significant differences (p = 0.387). There were no differences in the proportion of outliers (3-degree) found (p = 0.211). Nevertheless, a higher proportion of patients in the robotic group improved their mechanical alignment, as compared with conventional surgery (p = 0.023), although no differences were found when comparing with navigation (p = 0.121).

CONCLUSIONS

No statistically significant differences were found with respect to the postOp alignment achieved. However, statistically significant differences were detected between robotic and conventional surgery when considering the percentage of patients with improved limb alignment.

Robotic-assisted TKA reduces surgery duration, length of stay and 90-day complication rate of complex TKA to the level of noncomplex TKA

INTRODUCTION

Complex primary total knee arthroplasties (TKA) are reported to be associated with excessive episode of care (EOC) costs as compared to noncomplex procedures. The impact of robotic assistance (rTKA) on economic outcome parameters in greater case complexity has not been described yet. The purpose of this study was to investigate economic outcome parameters in the 90-days postoperative EOC in robotic-assisted complex versus noncomplex procedures.

MATERIALS AND METHODS

This study is a retrospective, single-center review of 341 primary rTKAs performed between 2017 and 2020. Patient collective was stratified into complex (n = 218) and noncomplex TKA (n = 123) based on the presence of the following criteria: Obese BMI, coronal malalignment, flexion contracture > 10°, posttraumatic status, previous correction osteotomy, presence of hardware requiring removal during surgery, severe rheumatoid arthritis. Group comparison included surgery duration, length of stay (LOS), surgical site complications, readmissions, and revision procedures in the 90-days EOC following rTKA.

RESULTS

The mean surgery duration was marginally longer in complex rTKA, but showed no significant difference (75.26 vs. 72.24 min, p = 0.258), neither did the mean LOS, which was 8 days in both groups (p = 0.605). No differences between complex and noncomplex procedures were observed regarding 90-days complication rates (7.34 vs. 4.07%, p = 0.227), readmission rates (3.67 vs. 3.25%, p = 0.841), and revision rates (2.29 vs. 0.81%, p = 0.318).

CONCLUSIONS

Robotic-assisted primary TKA reduces the surgical time, inpatient length of stay as well as 90-days complication and readmission rates of complex TKA to the level of noncomplex TKA. Greater case complexity does not seem to have a negative impact on economic outcome parameters when surgery is performed with robotic assistance.