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Purpose: This study reports the five-year functional outcomes from a prospective cohort study comparing robotic-arm assisted total knee arthroplasty (RO TKA) versus conventional manual total knee arthroplasty (CO TKA)., Methods: This prospective single-surgeon study included 120 patients with symptomatic end-stage knee arthritis undergoing primary TKA. This included 60 consecutive patients undergoing CO TKA followed by 60 consecutive patients undergoing RO TKA using a semi-automated robotic device. Study patients were reviewed at one, two, and five years after surgery and the following outcomes recorded: The University of California at Los Angeles activity-level (UCLA), Knee Society Score (KSS), Oxford Knee Score (OKS) Forgotten Joint Score (FJS), and any complications., Results: There were no statistical differences between RO TKA and CO TKA in the median UCLA score (p = N.S), median KSS (p = N.S), and median OKS (p = N.S) at five-year follow-up. RO-TKA was associated with statistically significant improvements in the FJS at one (p = 0.001), two (p = 0.003), and five (p = 0.025) years of follow-up compared with CO TKA. There was no statistical difference in the incidence of knee stiffness requiring manipulation under anesthesia between the two treatment groups (p = N.S)., Conclusion: Patients in both treatment groups had excellent functional outcomes with comparable patient reported outcomes at five-year follow-up. RO TKA was associated with statistically significant improvements in the FJS compared with CO TKA, but these differences did not reach the minimal clinically important difference at any follow-up interval. There was no overall difference in complications between the two treatment groups at five-year follow-up., Level of Evidence: II (Prospective cohort study)., (© 2023. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: The increasing number of patients experiencing periprosthetic total knee arthroplasty (TKA) infections and the cost of treating them suggest that we seek alternatives to two-stage revision. Single-stage revision is a potential alternative to the standard two-stage procedure because it involves only one surgical procedure, so if it is comparably effective, it would be associated with less patient morbidity and lower cost., Questions/purposes: We compared (1) the degree to which our protocol of a highly selective single-stage revision approach achieved infection control compared with a two-stage revision approach to TKA infections; and (2) Knee Society scores and radiographic evidence of implant fixation between the single-stage and two-stage patients who were treated for more complicated infections., Methods: Between 2004 and 2009, we treated 102 patients for chronic TKA infections, of whom 28 (27%) were treated using a single-stage approach and 74 (73%) were treated using a two-stage approach. All patients were available for followup at a minimum of 3 years (mean, 6.5 years; range, 3-9 years). The indications for using a single-stage approach were minimal/moderate bone loss, the absence of immunocompromise, healthy soft tissues, and a known organism with known sensitivities for which appropriate antibiotics are available. Participants included 38 men and 64 women with a mean age of 65 years (range, 45-87 years). We used the Musculoskeletal Infection Society definition of periprosthetic joint infection to confirm infection control at the last followup appointment. Radiographs were evaluated for signs of loosening, and patients completed Knee Society Scores for clinical evaluation., Results: None of the patients in the single-stage revision group developed recurrence of infection, and five patients (93%) in the two-stage revision group developed reinfection (p=0.16). Patients treated with a single-stage approach had higher Knee Society scores than did patients treated with the two-stage approach (88 versus 76, p<0.001). However, radiographic findings showed a well-fixed prosthesis in all patients with no evidence of loosening at last followup in either group., Conclusions: Our data provide preliminary support to the use of a single-stage approach in highly selected patients with chronically infected TKAs as an alternative to a two-stage procedure. However, larger, multicenter, prospective trials are called for to validate our findings., Level of Evidence: Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Background: A knee design with a ball-and-socket articulation of the medial compartment has a femoral rollback profile similar to the native knee. Compared to a conventional, posterior-stabilized knee design, it provides AP stability throughout the entire ROM. However, it is unclear whether this design difference translates to clinical and functional improvement., Questions/purposes: We asked whether the medially conforming ball-and-socket design differences would be associated with (1) improved ROM; and (2) improved American Knee Society, WOMAC, Oxford Knee, SF-36, and Total Knee Function Questionnaire scores compared to a conventional, fixed-bearing posterior-stabilized TKA., Patients and Methods: We enrolled 82 patients in a single-center, single-blinded, randomized, controlled trial comparing the medially conforming ball-and-socket design knee prosthesis to a posterior-stabilized total knee prosthesis. Our primary end point was ROM. Our secondary end points were American Knee Society, WOMAC, Oxford Knee, SF-36, and Total Knee Function Questionnaire scores. All patients were followed at 1 and 2 years., Results: The mean ROM was 100.1° and 114.9° in the posterior-stabilized and medially conforming ball-and-socket groups, respectively. The physical component scores of SF-36 and Total Knee Function Questionnaire were better in the medially conforming ball-and-socket group. We found no difference in American Knee Society, WOMAC, and Oxford Knee scores., Conclusions: Both implant designs similarly relieved pain and improved function. The medially conforming ball-and-socket articulation provided better high-end function as reflected by the Total Knee Function Questionnaire., Level of Evidence: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: There is limited information regarding revision total knee arthroplasty (TKA) with respect to etiology, outcome, and long-term survival comparing different implant types., Questions/purposes: We compared patient outcomes, survivorship and modes of failure and the most common etiologic factors for rerevision between different revision implant types., Methods: We retrospectively reviewed 349 cases of revision TKA in 343 patients whose mean age was 67.8 years. Three implant types were used: posterior stabilized, condylar constrained knee, and rotating hinge. The etiologies included infection (32.7%), aseptic loosening (14.9%), and polyethylene wear (12.3%). The minimum followup was 12 months (mean, 57.7 months; range, 12-120 months)., Results: The mean Knee Society scores were 89 (range, 48-94), 88.9 (range, 45-95), and 84 (range, 56-94) and the mean ranges of motion were 110.0 degrees (range, 70 degrees -125 degrees ), 106.1 degrees (range, 70 degrees -120 degrees ), and 111.7 degrees (range, 85 degrees -125 degrees ) for the posterior stabilized, condylar constrained knee, and rotating hinge types, respectively. The rotating hinge group had the highest satisfaction rates (88%). Overall 10-year survivorship was 90.6% with highest survivorship seen in the rotating hinge group. The most common causes for rerevision were infection (2.9% of our cohort), instability (1.7%), and aseptic loosening (1.4%). The mean overall time to rerevision was 69.9 months (range, 11-119 months)., Conclusions: In our experience periprosthetic infection is the most common cause of failure of both primary and revision TKA. Functional outcome and range of motion improve irrespective of revision implant type. The rotating hinge prosthesis provides patient satisfaction and survivorship similar to that of other implant types., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.