Accuracy of tibial component positioning in the robotic arm assisted versus conventional unicompartmental knee arthroplasty

The Deep-MCL Line: A Reliable Anatomical Landmark to Optimize the Tibial Cut in UKA

The extramedullary guides for the tibial resection during medial unicompartmental knee arthroplasty (UKA) are inaccurate, with an error risk in coronal and sagittal planes and cut thickness. It was our hypothesis that the use of anatomical landmarks for the tibial cut can help the surgeon to improve accuracy. The technique described in this paper is based on the use of a simple and reproducible anatomical landmark. This landmark is the line of insertion of the fibers of the deep medial collateral ligament (MCL) around the anterior half of the medial tibial plateau called the "Deep MCL insertion line". The used anatomical landmark determines the orientation (in the coronal and sagittal planes) and the thickness of the tibial cut. This landmark corresponds to the line of insertion of the fibers of the deep MCL around the anterior half of the medial tibial plateau. A consecutive series of patients who underwent primary medial UKA between 2019 and 2021 were retrospectively reviewed. A total of 50 UKA were included. The mean age at the time of surgery was 54.5 ± 6.6 years (44-79). The radiographic measurements showed very good to excellent intra-observer and inter-observer agreements. The limb and implant alignments and the tibial positioning were satisfying, with a low rate of outliers and good restoration of the native anatomy. The landmark of the insertion of deep MCL constitutes a reliable and reproducible reference for the tibial cut axis and thickness during medial UKA, independent of the wear severity.

How reproducible are clinical measurements in robotic knee surgery?

PURPOSE

Robotic-assisted surgery has been recently introduced to improve biomechanical restoration, and thus better clinical and functional outcomes, after knee joint arthroplasty operations. Robotic-assisted uni-compartmental knee arthroplasty (UKA) aims indeed to improve surgical bone resection and alignment accuracy, optimized component positioning and knee balancing, relying on a series of calibration measurements performed during the surgery. These advantages focus therefore on improving the reproducibility of UKA surgeries, reducing (if not eliminating) eventual differences among high- and low-volume surgeons. The purpose of this study is to investigate and quantify the reproducibility of in-vivo measurements performed with a robotic system: the intra- and inter-observer variability of a series of measurements was therefore analyzed and compared among differently experienced operators.

METHODS

Five patients were analyzed and underwent robotic-assisted UKA using a semi-active robotic system. Three different observers with different experience levels were involved to independently perform the measurements of two parameters of the preoperative knee (Hip-Knee-Ankle angle [HKAa], Internal-External Rotation) at different degrees of knee flexion. Inter-observer and intra-observer comparisons were performed.

RESULTS

The average variability in the measurements obtained from the intra-observer and inter-observer comparisons were always < 0.68° for HKAa and < 2.59° for internal-external rotation, and the ICCs showed excellent agreement (> 0.75) for most cases and good agreement (> 0.60) in the remaining ones.

CONCLUSION

This study demonstrated high reproducibility of the measurements obtainable in clinical environment with the robotic system. The inter-observer results furthermore showed that the level of confidence with the robotic system is not significantly influencing the measurement.

Better accuracy and implant survival in medial imageless robotic-assisted unicompartmental knee arthroplasty compared to conventional unicompartmental knee arthroplasty: two- to eleven-year follow-up of three hundred fifty-six consecutive knees

PURPOSE

Implant malpositioning, joint line (JL) lowering, and malalignment have been identified as risk factors for implant failure in unicompartmental knee arthroplasty (UKA). The aims of this study were to compare the accuracy of implant positioning in robotic-assisted UKA versus conventional UKA in a large cohort and examine the correlation with implant survival at mid-term follow-up.

METHODS

This retrospective study included 356 medial UKAs from 2011 to 2019. The radiological measurements performed were coronal positioning of tibial implant according to Cartier angle (Δ Cartier), posterior tibial slope (PTS), residual hip-knee-ankle (HKA), and JL restoration. Outliers were defined as follows: post-operative HKA < 175° or > 180°, Δ Cartier > 3° or <  - 3°, JL change ≥ 2 mm, and PTS < 2° or > 8°. The survival probability was reported at the last follow-up.

RESULTS

Out of the 356 knees included, 159 underwent conventional UKA (44.5%) and 197 (55.5%) robotic-assisted UKA. The mean follow-up was 61.3 months ± 24.0. Robotic UKA was associated with better accuracy compared to conventional UKA in relation to HKA (67% vs 56%, p = 0.023), JL restoration (70% vs 44%, p < 0.0001), PTS (83% vs 55%, p < 0.0001), and tibial varus restoration (65% vs 55%, p = 0.049). Implant survival in the robotic group was found to be superior at the last follow-up (96.4% versus 87.3% at 9 years, p = 0.004).

CONCLUSION

Robotic assistance in patients undergoing medial UKA was associated with better accuracy compared to conventional UKA with respect to tibial implant positioning, post-operative limb alignment, and JL restoration. This was translated in improved survival at mid-term follow-up favouring the robotic group.

Image-based robot assisted bicompartmental knee arthroplasty versus total knee arthroplasty

OBJECTIVE

To evaluate the short-term clinical outcomes of image-based robot-assisted bicruciate retaining bicompartmental knee arthroplasty and compare it to robot-assisted total knee arthroplasty in the Indian population.

METHODS

Between December 2018 and November 2019, five patients (six knees) underwent robot-assisted bicompartmental knee arthroplasty (BCKA). These patients were demographically matched with five patients (six knees) who underwent robot-assisted total knee arthroplasty (TKA) during the same period. Clinical outcomes of these twelve knees were assessed in the form of knee society score (KSS) score, Oxford knee score (OKS), and forgotten joint score (FJS) after a minimum follow-up period of 25 months. The data between the two cohorts were compared and analyzed.

RESULTS

Scores obtained from both cohorts were subjected to statistical analysis. SPSS software was utilized and the Mann Whitney U-test was utilized to compare the two groups. There was no statistically significant difference found between the two groups in terms of functional outcome.

CONCLUSION

Image-based robot-assisted BCKA is a bone stock preserving and more physiological procedure which can be a promising alternative to patients presenting with isolated arthritis of only two compartments of the knee. Although long-term, larger trials are warranted to establish it as an alternative, our pilot study shows an equally favorable outcome as TKA, making it an exciting new avenue in the field of arthroplasty.

Short-Term Outcomes of Robotic Lateral Unicompartmental Knee Arthroplasty: An Indian Perspective

BACKGROUND

Lateral UKA is a technically more challenging procedure than medial UKA accounting for < 1% of all knee arthroplasties. Robotic UKA for lateral compartment arthritis is rare and has not been reported in India.

MATERIALS AND METHODS

This is a prospective single-centre clinical study of six patients (five females and one male) who underwent robotic-arm-assisted lateral UKA (RALUKA) between May 2018 and January 2020 with patient-specific 3D-CT preoperative plan. Overall satisfaction on a five-level Likert scale, clinical outcome based on the KOOS and MFJS and radiological outcomes based on the HKA axis, femorotibial angle (FTA), tibial posterior slope (PS) obtained were compared preoperatively and postoperatively.

RESULTS

At a mean follow-up period of 23.84 months, among six patients 33.3% very satisfied, 50% satisfied and 16.7% felt neutral. The mean KOOS changed from 63.03 ± 3.52 to 93.95 ± 3.25 and the mean MFJS was 75.41 ± 10.29 postoperatively. The mean HKA axis changed from 175.81° ± 2.88 valgus to 179.99° ± 2.14 neutral alignment. The mean correction attained was from 4.19° ± 2.88 valgus deformity to 0.01° ± 2.14. The mean FTA and the mean PS changed from 7.34° ± 4.14 of valgus to 1.92° ± 1.85 of valgus and 83.44° ± 1.77 to 85.38° ± 2.10, respectively.

CONCLUSIONS

The mean preoperative and postoperative KOOS showed a statistical significance with a p value of < 0.001 (< 0.05), showing significant improvement with RALUKA. RALUKA is a promising surgical option for lateral compartment OA of the knee.

Navigation und Robotik in der Knieendoprothetik

Hintergrund

Die Langlebigkeit einer Knieprothese hängt von der korrekten Ausrichtung der Prothesenkomponenten und der mechanischen Achse des Beins sowie einer optimalen Weichteilbalancierung ab. Um dieses Ziel präziser und sicherer zu erreichen, wurde die computerassistierte Chirurgie entwickelt. Ziel dieses Artikels ist es, die Navigation und Robotik zu bewerten und die aktuellen Ergebnisse zu diskutieren.

Methode

Umfassende Literaturrecherche in der Datenbank PubMed und dem Suchdienst Google Scholar.

Ergebnisse

Die computerassistierte Chirurgie führt zu einer präziseren Ausrichtung der mechanischen Beinachse und der Positionierung der Prothesenkomponenten. Trotzdem sind die klinischen Ergebnisse zur Kniefunktion und die Resultate der patientenbezogenen Fragebögen (PROMs) kontrovers. Sie zeigen, wie für die Überlebensrate, keinen signifikanten Unterschied zur konventionellen Technik. Hohe Anschaffungs- und Unterhaltskosten limitieren zudem die Verbreitung dieser Systeme.

Schlussfolgerung

Momentan bietet die bildgestützte Navigation dem Chirurgen bei gewissen Operationsschritten eine wertvolle Unterstützung für ein präziseres und sichereres Arbeiten. Trotzdem sind Langzeitstudien zur Kniefunktion, zu den PROMs, zur Überlebensrate dringend erforderlich. In der Robotik zeigen nur kurzfristige Ergebnisse ähnliche Trends wie bei der Navigation. Die Robotiksysteme müssen und werden sich weiterentwickeln, um den Anforderungen der Nutzer und Patienten zu entsprechen (Kosten, Größe, Programmierung).

Accuracy in the Execution of Pre-operative Plan for Limb Alignment and Implant Positioning in Robotic-arm Assisted Total Knee Arthroplasty and Manual Total Knee Arthroplasty: A Prospective Observational Study

AIM

The objective of the study is to compare the accuracy of implant positioning and limb alignment achieved in robotic-arm assisted total knee arthroplasty(RATKA) and manual total knee arthroplasty(MTKA) to their respective preoperative plan.

PATIENTS AND METHODS

This was a prospective observational study conducted in a tertiary care centre between August 2018 and January 2020. 143 consecutive RATKA(105 patients) and 151 consecutive MTKA(111 patients) performed by two experienced arthroplasty surgeons were included. Two independent observers evaluated the accuracy of implant positioning by measuring the radiological parameters according to the Knee-Society-Roentgenographic-Evaluation-System and limb alignment from postoperative weight-bearing scanogram. Outcomes were defined, based on the degree of deviation of measurements from the planned position and alignment, as excellent(0-1.99°), acceptable(2.00-2.99°) and outlier(≥ 3.00°).

RESULTS

There were no systematic differences in the demographic and baseline characteristics between RATKA and MTKA. Statistically significant outcomes were observed favouring robotic group for postoperative mechanical axis (p < .001), coronal inclination of the femoral component (p < 0.001), coronal inclination of tibial component (p < 0.001), and sagittal inclination of tibial component (p < 0.001). There was no significant difference in the sagittal inclination of the femoral component (p = 0.566). The percentage of knees in the 'excellent' group were higher in RATKA compared to MTKA. There was absolutely no outlier in terms of limb alignment in the RATKA group versus 23.8% (p < 0.001) in the MTKA group. All the measurements showed high interobserver and intraobserver reliability.

CONCLUSION

Robotic-arm assisted TKA executed the preoperative plan more accurately with respect to limb alignment and implant positioning compared to manual TKA, even when the surgeons were more experienced in the latter.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-020-00324-y.