A Newly Designed “SkyWalker” Robot Applied in Total Knee Arthroplasty: A Retrospective Cohort Study for Femoral Rotational Alignment Restoration

Abstract

Objective This study explored whether robotic arm‐assisted total knee arthroplasty (RATKA) has the advantage of restoring femoral rotational alignment compared to conventional total knee arthroplasty (COTKA). Methods Sixty patients (45 women and 15 men) attending our department from May 2019 to December 2020 were selected and divided into two groups, with 30 patients in each group, according to whether they underwent COTKA or RATKA. Femoral rotational alignment results, such as, posterior condylar angle (PCA), patella transverse axis‐femoral transepicondylar axis angle (PFA), radiological findings, such as, hip‐knee‐ankle angle (HKA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA), and operative data (operation time, intraoperative blood loss, tourniquet time, and length of stay (LOS), and clinical outcomes, such as maximum knee flexion angle (MKFA), Knee Society Score (KSS), and Western Ontario Mac Master University Index Score (WOMAC) were compared within and between the two groups. Results PCA and PFA in the RATKA group were (0.6 ± 0.3)° and (0.9 ± 0.3)°, respectively, which were smaller than (1.5 ± 2.0)° and (3.1 ± 1.1)° in the COTKA group ( P < 0.05), and were closer to 0°; the differences in HKA, LDFA, and MPTA were not statistically significant. With the exception of the LDFA, the HKA, MPTA, PCA, and PFA improved in both groups after surgery ( P < 0.05). The blood loss and the LOS of RATKA group were 192.3 ± 23.1 mL and 8.2 ± 1.4 days, which were less than 203.7 ± 29.8 mL and 9.3 ± 1.1 days of the COTKA group, but the operation time showed no statistically significant difference, and the tourniquet time was longer ( P < 0.05). The MKFA in the RATKA group was (123.0 ± 3.7)°, which was greater than (116.3 ± 4.6)° in the COTKA group ( P < 0.05). In terms of scores, the postoperative results were better than the preoperative results in both groups ( P < 0.05). However, there was no statistically significant difference between the groups. Conclusion The accuracy of femoral rotational alignment reconstructed achieved by RATKA is significantly better than that of COTKA and is more conducive to the recovery of knee flexion function after surgery; although RATKA reduces intraoperative blood loss and postoperative LOS, the short‐term clinical efficacy comparison has not yet demonstrated the advantages of robotic technology, and a more optimized design is needed to improve the efficiency of RATKA surgery.

Evaluation of the External Rotation of femur component in functionally aligned Robotic Assisted Total Knee Arthroplasty

“…Precise alignment and rotation of implants play a pivotal role in the success of TKA, as any misalignment can result in issues like abnormal wear, premature loosening, and patellofemoral issues [18,19,20]. The fusion of navigation and robotic surgery has ushered in the functional alignment concept, enabling surgeons to utilize 3D simulations and real-time ligament tension data for precise adjustments during knee arthroplasty [21,22]. Research indicates that RA-TKA technology excels in gap balancing and accurately restores the joint line while preserving near-normal knee kinematics [22].…”

“…The fusion of navigation and robotic surgery has ushered in the functional alignment concept, enabling surgeons to utilize 3D simulations and real-time ligament tension data for precise adjustments during knee arthroplasty [21,22]. Research indicates that RA-TKA technology excels in gap balancing and accurately restores the joint line while preserving near-normal knee kinematics [22]. The improved precision of component placement in the sagittal plane with RA-TKA potentially facilitates greater accuracy in knee gap balancing than C-TKA [23].…”

“…For satisfactory and optimal TKA outcomes, ensuring accurate rotational alignment of the femoral component is important [27]. While excessive external rotation may cause post-operative pain (including pain in anterior part of knee), exion and mid-exion instability, and stiffness, internal rotation result in patellar maltracking and instability [22,28]. In a study assessing 190 CT scans in which 65% of the healthy knee joints revealed an 3° internal rotation [29].…”

Evaluation of the External Rotation of the Femur Component in Functionally Aligned Robotic-Assisted Total Knee Arthroplasty

“…Research indicates that RA-TKA technology excels in gap balancing and accurately restores the joint line while preserving near-normal knee kinematics [19]. The improved precision of component placement in the sagittal plane with RA-TKA potentially facilitates greater accuracy in knee gap balancing than C-TKA [20].…”

Robotic Total Knee Arthroplasty: An Update

“…Preliminary results in China show good bone resection accuracy [ 41 ] and greater component alignment, with no changes in functional scores [ 42 ]. Surgical time is increased, while blood loss is unexpectedly decreased [ 43 ].…”