Robotic-assisted total knee arthroplasty improves the rotational mismatch between femoral and tibial components, but not the forgotten joint score 12: a single-center retrospective cohort study.

PURPOSE: The primary aim of this study was to compare postoperative short-term patient reported outcome measurements (PROMs) and rotational mismatch between femoral and tibial following conventional jig-based total knee arthroplasty (Conv-TKA) versus robotic-assisted TKA (RA-TKA) using three-dimensional computed tomography (3DCT) measurements. METHODS: This retrospective, consecutive case-control trial included 83 patients with varus osteoarthritis of the knee undergoing Conv-TKA versus RA-TKA using bi-cruciate stabilized TKA. The rotational mismatch of the femoral and tibial components between the two groups were compared using 3DCT measurements. PROMs (2011 Knee Society Score (KSS), forgotten joint score-12 (FJS-12), patella score were compared in patients between 1 and 2 years postoperatively. RESULTS: The two groups did not exhibit significant differences in any of the following preoperative factors: age at surgery, body mass index (BMI), preoperative range of motion (ROM), hip-knee-ankle (HKA) angle. There were no significant differences in postoperative HKA angle and tibial rotation angle, the absolute values of the femoral rotational angle and rotational mismatch were significantly smaller in the RA-TKA group than in the Conv-TKA group (both p < 0.01). Neither Postoperative PROMs (2011 KSS: pain, patient satisfaction, patient expectation, advanced activities score) nor patella score differed significantly between the groups, but FJS-12 was significantly better in the Conv-TKA group than in the RA-TKA group (p < 0.01). CONCLUSIONS: RA-TKA did not improve FJS-12 compared to Conv-TKA, but did result in more accurate rotational alignment of femoral component and rotational mismatch between the femoral and tibial components. LEVEL OF EVIDENCE: IV.

Analysis of Gait Ability and Patient Reported Outcome Measurements after Robotic-assisted Total Knee Arthroplasty for Osteoarthritis of the Knee with Windswept Deformity.

Introduction: Windswept deformity (WD) refers to valgus deformity in one knee and varus deformity in the other. We performed robotic-assisted (RA) total knee arthroplasty (TKA) for osteoarthritis of the knee with WD, made patient reported outcome measurements (PROMs), and performed gait analysis based on triaxial accelerometery. Case Report: A 76-year-old woman presented to our hospital with bilateral knee pain. Image-free handheld RA TKA was performed on the left knee with severe varus deformity and severe pain during walking. RA TKA was performed on the right knee with severe valgus deformity 1 month later. The RA technique was used to determine implant positioning and the plan for osteotomy intraoperatively, taking into account soft-tissue balance. This made it possible to use a posterior stabilized implant instead of a semi-constrained implant for severe valgus knee deformity with flexion contracture (Krachow classification Type 2). At 1 year after TKA, PROMs were inferior in the knee with pre-operative valgus deformity. Gait ability improved after surgery. Even with the RA technique, it took 8 months to achieve left-right balance while walking and for the variability of the gait cycle to become equivalent to that of a normal knee. Conclusion: Primary RA TKA is a viable option for osteoarthritis of the knee with WD. It took time for the gait ability of both knees to become equal and PROMs were better with the varus deformity compared to before surgery.

Coronal alignment classes after robotic-assisted total knee arthroplasty are not associated with variation in patient-reported outcome measurements: A single-center cohort study.

BACKGROUND: The aims of this study were (1) to use three-dimensional computed tomography (3DCT) measurements to determine whether patients undergoing imageless robotic-assisted total knee arthroplasty (RA-TKA) develop a variety of postoperative distal femoral mechanical angle (FMA), proximal tibial mechanical angle (TMA), and hip-knee-ankle angle (HKA) phenotypes as described by Hirschmann et al, and (2) to compare postoperative patient-reported outcome measurements (PROMs) between these phenotypes. METHOD: Fifty patients with knee osteoarthritis underwent RA-TKA. All surgeries were performed using bicruciate-stabilized TKA. In each case, the postoperative HKA, FMA and TMA were classified into one of Hirschmann's five FMA, five TMA, and seven HKA phenotype categories. We investigated how these phenotypes affected patient satisfaction, 2011 Knee Society Score (KSS) subscale scores, the Forgotten Joint Score-12 (FJS-12) score, and patella scores with anterior knee pain at a mean of 15.1 months after RA-TKA. RESULTS: Coronal alignment angles were assigned to three FMA, four TMA, and five HKA phenotypes. The most common FMA, TMA, and HKA phenotypes were valgus FMA 3° (58%), valgus TMA 3° (60%), and varus HKA 3° (38%). The FMA, TMA, and HKA phenotypes showed no significant differences in any PROMs. CONCLUSIONS: RA-TKA led to various HKA, FMA and TMA phenotypes in the coronal plane, none of which affected PROMs.

Intraoperative joint balancing procedure using an imageless robotic assisted technique does not necessarily result in kinematically aligned bicruciate stabilized total knee arthroplasty.

The primary aim of this study was to retrospectively evaluate the hip- knee- ankle. (HKA) angle and prosthetic alignment with three-dimensional computed tomography (3DCT) measurements in patients who underwent robotic-assisted (RA) TKA, with consideration of the soft tissue envelope via an intraoperative joint-balancing procedure. We hypothesized that intraoperative consideration of soft tissue laxity in individual patients using imageless RA technology will not necessarily result in kinematically aligned bicruciate stabilized total knee arthroplasty (KA TKA). This retrospective study included consecutive patients who underwent RA TKA between 2019 and 2020. The indication for TKA was varus osteoarthritis of the knee. During this period, 60 RA bi-cruciate stabilized TKAs were performed. Prosthetic alignments were measured using computer software with 3DCT. We determined prosthetic positioning and bone resection volume with consideration of the soft tissue envelope using an intraoperative full range of motion joint-balancing procedure during RA TKA. 3DCT scans of the entire lower extremity were taken before and after surgery. Postoperative varus HKA alignment occurred in 58% of patients who underwent RA TKA, 31% of knees were in femoral valgus alignment and tibial varus alignment, and 42% had femoral components in internal rotation among knees with femoral valgus alignment and tibial varus alignment. The mean thickness of the osteotomized medial and lateral posterior condyles of the femur were 11.2 and 9.1 mm, respectively, based on 3DCT measurements. Intraoperative consideration of soft tissue laxity in individual patientsusing an imageless RA technique does not necessarily result in KA bicruciate TKA.

The importance of selecting a cruciate-retaining total knee prosthesis for a patient with a large physiological posterior tibial slope: a case report.

For Japanese individuals, deep bending is inevitable in their daily lives, such as during seiza sitting and kneeling. Thus, achieving a good post-operative range of motion is an important factor in improving patient satisfaction. Even normal knees often have a posterior tibial slope of more than 10°. We report the case of a 76-year-old woman who underwent proximal tibial osteotomy at 8° with the Vanguard Knee cruciate retaining total knee arthroplasty (TKA) system. She required the revision TKA 10 years later due to ultra-high-molecular-weight polyethylene wear and breakage of the posteromedial tibial component.