In total knee arthroplasty (TKA), surgeons often face the decision of maximizing tibial component fit and achieving correct rotational alignment at the same time. Customized implants (CIMs) address this difficulty by aiming to replicate the anatomical joint structure, utilizing data from patient-specific knee geometry during the manufacturing. We intraoperatively compared component fit in four tibial zones of a CIM to that of three different off-the-shelf (OTS) TKA designs in 44 knees. Additionally, we assessed the rotational alignment of the tibia using computed tomography (CT)-based computer aided design model analysis. Overall the CIM device showed significantly better component fit than the OTS TKAs. While 18% of OTS designs presented an implant overhang of 3 mm or more, none of the CIM components did (p < 0.05). There was a larger percentage of CIMs seen with optimal fit (≤1 mm implant overhang to ≤1 mm tibial bone undercoverage) than in OTS TKAs. Also, OTS implants showed significantly more component underhang of ≥3 mm than the CIM design (37 vs. 18%). The rotational analysis revealed that 45% of the OTS tibial components showed a rotational deviation of more than 5 degrees and 4% of more than 10 degrees to a tibial rotational axis described by Cobb et al. No deviation was seen for the CIM, as the device is designed along this axis. Using the medial one-third of the tibial tubercle as the rotational landmark, 95% of the OTS trays demonstrated a rotational deviation of more than 5 degrees and 73% of more than 10 degrees compared with 73% of CIM tibial trays with more than 5 degrees and 27% with more than 10 degrees. Based on our findings, we believe that the CIM TKA provides both better rotational alignment and tibial fit without causing overhang of the tibial tray than the three examined OTS implants.

Background: In this study, we assessed implant survivorship, patient satisfaction, and patient-reported functional outcomes at approximately 2 years for patients who had received a customized posterior-stabilized (PS) knee replacement system. We hypothesized that the customized PS implant would have high overall patient-reported outcomes because of its patient-specific design.Methods: Ninety-three patients (100 knees) who had received the customized total knee replacement system were enrolled at 2 centers. The patients’ length of hospitalization and preoperative pain intensity were assessed. At a single follow-up time-point, we assessed patient-reported outcomes utilizing the Knee injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR), satisfaction rates, implant survivorship, and patients’ perception of their knee.Results: At an average follow-up time of 1.9 years (range, 1.5 to 2.4 years), implant survivorship was found to be 100%. From an average preoperative baseline pain rating of 6.5 (range, 3 to 10) until the time of follow-up, we observed an average decrease of 5.2 on the numeric pain rating scale to an average of 1.3 (range, 0 to 8), indicating satisfactory pain relief after the procedure. The satisfaction rate was found to be high, with 90% of patients being satisfied or very satisfied and 88% of patients reporting a “natural” perception of their knee either some or all of the time. The evaluation of the patient-reported outcome measure showed satisfactory results with a high KOOS JR average score of 90 (range, 34 to 100) at the time of follow-up.Conclusions: Based on our results, we believe that the customized PS implant provides patients with excellent postoperative outcomes.Level of Evidence:TherapeuticLevel IV. See Instructions for Authors for a complete description of levels of evidence.

Background: The purpose of this retrospective study was to compare clinical outcome results, perceived function, and overall preference among patients who had undergone staged bilateral total knee arthroplasty (TKA) with a cruciate-retaining, customized implant (customized TKA, or C-TKA) in 1 knee and an off-the-shelf (OTS) implant in the contralateral knee. Methods: Forty-seven patients (94 knees) from a single study center who underwent C-TKA in 1 knee and had previously undergone TKA with an OTS implant in the contralateral knee were included in this study. As the primary outcome measures, the Knee injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS, JR) and the Forgotten Joint Score (FJS) were self-administered by the study subjects at a single follow-up time point. Additionally, a follow-up questionnaire to compare patients’ perceived joint stability, knee mobility, perceived feeling of the replaced joint, pain levels, and overall preference between their knees was administered. Results: The average follow-up was 2.3 years (range, 0.7 to 3.8 years) for C-TKA and 6.7 years (range, 1.6 to 11.1 years) for the OTS TKA. Significantly higher KOOS, JR (82 versus 77; p = 0.03) and FJS (68 versus 58; p = 0.04) results were found with C-TKA. The evaluation of the follow-up questionnaire showed that more patients reported having “a little” or “a lot” less pain (49% versus 15%), better perceived mobility (45% versus 12%) and stability (36% versus 13%), and a more “normal” feeling of their knee (60% versus 10%) with the C-TKA implant compared with their OTS counterpart. When patients were asked to directly compare their knees, we found that 72.3% of the patients preferred the knee that received C-TKA over the contralateral OTS knee replacement, with 21.3% seeing no difference and 6.4% preferring the OTS knee replacement. Conclusions: We believe that this is the first study to examine patient-reported outcomes of customized and OTS TKA implant designs in the same patient. We conclude that patients in this study cohort who underwent staged bilateral TKA with a C-TKA implant in 1 knee and an OTS prosthesis in the other knee reported better for their patient-specific knee replacement, with higher FJS and KOOS, JR values, and overall, preferred the C-TKA knee more often compared with the OTS knee replacement. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background: Customized total knee arthroplasty (C-TKA) systems are becoming increasingly popular in patients with end-stage knee arthritis. Manufactured with use of patient data derived from computed tomography or magnetic resonance imaging, these systems aim to restore the individual bone anatomy of the patient by providing customized fit and geometries. This retrospective study investigated implant survivorship, patient satisfaction, and functional outcomes following C-TKA with a cruciate-retaining prosthesis. Methods: We retrospectively reviewed data from 540 knees in 433 patients who underwent C-TKA performed by a single surgeon at a single institution. Patient demographics, surgical variables, complications, and reoperations were evaluated. Follow-up evaluations were performed via a single telephone call to assess patient satisfaction, functional outcomes according to the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) questionnaire, and implant survivorship following C-TKA. Descriptive statistics were analyzed. Results: At the time of C-TKA, the mean age was 71.8 years and the mean body mass index was 29.1 kg/m². The mean follow-up was 2.8 years. Patient satisfaction was high, with 89% of C-TKA patients being either satisfied or very satisfied. The mean KOOS-JR was 82. There were 8 revisions (1.5%) at an average of 0.7 years after the index C-TKA; hence, there was an implant survivorship of 98.5%. Conclusions: To our knowledge, this was the largest retrospective study to date to report on patient satisfaction, functional outcomes, and implant survivorship following C-TKA. We observed a high satisfaction rate, satisfactory functional outcomes, and high implant survivorship at midterm follow-up. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Purpose: To treat patients with tricompartimental knee osteoarthritis (OA), a customized cruciate-retaining total knee arthroplasty (CCR-TKA) system can be used, including both individualized instrumentation and implants. The objective of this monocentric cohort study was to analyze patient-reported and functional outcomes in a series of patients implanted with the second generation of this customized implant. Methods: At our arthroplasty center, we prospectively recruited a cohort of patients with tricompartmental gonarthrosis to be treated with total knee replacement (TKA) using a customized cruciate-retaining (CCR) implant design. Inclusion criteria for patients comprised the presence of intact posterior cruciate and collateral ligaments and a knee deformity that was restricted to <15° varus, valgus, or flexion contracture. Patients were assessed for their range of motion (ROM), Knee Society Score (KSS), Western Ontario and McMaster University osteoarthritis index (WOMAC), and short form (SF)-12 physical and mental scores, preoperatively, at 3 and 6 months, as well as at 1, 2, 3, and 5 years of follow-up (FU) postoperatively. Results: The average age of the patient population was 64 years (range: 40–81), the average BMI was 31 (range: 23–42), and in total, 28 female and 45 male patients were included. Implant survivorship was 97.5% (one septic loosening) at an average follow-up of 2.5 years. The KSS knee and function scores improved significantly (p < 0.001) from, respectively, 41 and 53 at the pre-operative visit, to 92 and 86, respectively, at the 5-year post-operative time point. The SF-12 Physical and Mental scores significantly (p < 0.001) improved from the pre-operative values of 28 and 50, to 50 and 53 at the 5-year FU, respectively. Patients experienced significant improvements in their overall knee range of motion, from 106° at the preoperative visit to 122°, on average, 5 years postoperatively. The total WOMAC score significantly (p < 0.001) improved from 49.1 preoperatively to 11.4 postoperatively at 5-year FU. Conclusions: Although there was no comparison to other implants within this study, patients reported high overall satisfaction and improvement in functional outcomes within the first year from surgery, which continued over the following years. These mid-term results are excellent compared with those reported in the current literature. Comparative long-term studies with this device are needed. Level of evidence 3b (individual case–control study).

Background/Objectives: This study evaluated the learning curve for robotic-assisted total knee arthroplasty (RA TKA) performed by three experienced surgeons, focusing on procedure duration, surgeon satisfaction, and confidence. Methods: A prospective study was conducted with three senior arthroplasty surgeons, each performing 15 RA TKA procedures using the Triathlon Knee System with the Robotic Arm Interactive Orthopedic (RIO) System. Data on preparation, cut-to-suture, and breakdown times were collected. Surgeon anxiety levels were measured preoperatively using the STAI-6 scale, while postoperative satisfaction and confidence were assessed via a questionnaire. Statistical analysis was conducted using GraphPad Prism. Results: Of 50 scheduled surgeries, 45 were completed. The average cut-to-suture time was 1 h 38 min, with significant time reductions in robotic-specific steps as experience increased. Comparing the first five surgeries to the last five, the time for navigation hardware mounting, landmarks registration, femur and tibia registration, and bone preparation decreased by up to 30% (p < 0.001 to p = 0.025). General instrument preparation time decreased by 20% (p = 0.004). Surgeon anxiety levels dropped, indicating increased comfort with the system, while postoperative surveys showed increased satisfaction and confidence. Conclusions: The study demonstrated a substantial learning curve for RA TKA, with improved efficiency and surgeon confidence by the fifteenth procedure. These findings highlight the potential for streamlined workflows and guide training for new adopters of robotic knee arthroplasty.