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Introduction: There has been debate regarding the advantages of cruciate-retaining over posterior stabilized (PS) knee arthroplasty and vice versa. Many authors consider any coronal plane deformity > 15° as a contraindication for cruciate-retaining total knee arthroplasty. We aimed to compare whether functional outcome, deformity correction, and survivorship of cruciate retaining knee arthroplasty (CR) for severe varus deformity are equivalent to that ofposterior cruciate ligament substituting (PS) for 6 years. Materials and Methods: We conducted a retrospective comparative study among patients who underwent Total Knee Replacement in the Orthopedics Department of a tertiary care hospital between 2016 and 2018 August who had a varus deformity of more than 15°. The first author exclusively performed CR operation (Group A) for all complex knees. In contrast, the second author performed PS surgery (Group B) for any coronal plane deformity over 15°. Clinical evaluation included completing a Knee Society Score (KSS) Evaluation Form. Pre-operative scoring was collected from the hospital database. All clinical examinations and radiographs at the final follow-up were done by the third author, who was unbiased and not involved with the initial patient care. Results: here were 39 patients in Group A (CR) and 28 patients in Group B (PS). In Group A, the mean pre-operative varus was 22.05 ± 2.72° and the pre-operative KSS was 32.94 ± 6.79. Postoperatively, the deformity corrected to a mean valgus of 5.48 ± 1.8° and mean KSS of 89.17 ± 5.79. In Group B, the mean pre-operative varus was 22.14±3.82° and pre-operative KSS was 32.82 ± 5.98. Postoperatively, the deformity corrected to a mean valgus of 4.85 ± 2.1° and mean KSS of 90.17 ± 5.13. The mean insert thickness was 11.76 ± 1.75 mm and 11.42 ± 1.75mm among the CRand PS groups, respectively. Concerning deformity correction (P = 0.19) and functional outcome (P = 0.46), both groups showed equal improvement with a 100% survival rate for 6 years. Conclusion: We concluded that CRknee replacements are possible with excellent functional and radiological outcomes in severe varus arthritic knees with a 100 % survival rate.

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BACKGROUND: A subject of ongoing debate among orthopedic surgeons is the importance of preserving the posterior cruciate ligament in total knee arthroplasty (TKA), but long-term survival studies are scarce. The aim of this study was to compare long-term survival rates, and clinical and radiological follow up of a double-blind randomized controlled trial comparing posterior cruciate-retaining (PCR) versus posterior-stabilizing (PS) implant design of an AGC TKA. METHODS: A total of 114 patients were included in the survival analysis (PCR n = 61; PS n = 53). Forty-five patients (PCR n = 25; PS n = 20) participated in the long-term follow up using patient-reported outcome measures (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short-Form Health Survey (SF-36) and Kujala score (measuring anterior knee pain)). Thirty-one patients were assessed with a physical test (Knee Society Score (KSS)) and radiographs. RESULTS: Overall survival rate was 95.6% (PCR 98.4% vs. PS 92.5%), with five patients having a major revision (PCR n = 1 vs. PS n = 4, respectively). Satisfying outcome scores for both groups were described at on average 12-year follow up with no significant differences in KSS knee and function scores, WOMAC, SF-36, or Kujala scores between groups. Radiographically, there were no findings of femoral or tibial loosening or polyethylene wear in either group. CONCLUSIONS: Good long-term survival rates were described for the PCR and the PS design of an AGC TKA. There were no significant differences in clinical and radiological outcomes between a PCR and a PS design 12 years postoperatively.

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INTRODUCTION: The outcomes of total knee arthroplasty (TKA) remain controversial, and we do not know which factors are important for successful outcomes. This study aimed to compare the mid-term outcomes of different conceptual designs by evaluating the radiological and clinical outcomes. MATERIALS AND METHODS: A total of 478 total knee arthroplasties (TKAs) were enrolled and allocated into groups I [posterior stabilizing (PS) with anterior referencing (AR)], II [PS with posterior referencing (PR), and III [ultra-congruent (UC) TKA)]. Preoperative findings, last follow-up clinical outcomes, and final follow-up radiological and indirect assessments of the femoral rollback were compared between the groups. RESULTS: The mean follow-up period was 72.6 ± 12.9 months. The tourniquet was used samely applied to every group. Flexion contracture was significantly larger in group III than in groups I and II (3.3 ± 2.7, p < 0.001), and further flexion was significantly smaller in group III (130.0° ± 2.7°, p < 0.001). Among the radiological parameters, posterior osteophyte formation was the most common in group III (67.8%). The rollback distance was significantly smaller in group III than in groups I and II (p < 0.001). The active deep flexion angle was affected by the posterior condylar offset (PCO) ratio, and the contact point changed the distance (p < 0.05). CONCLUSION: PS TKAs showed better ROMs than UC TKAs; however, no differences were noted in the clinical outcome scales. The flexion angle was affected by the PCOR and rollback at both PS and UC TKAs. However, rollback negatively affected the flexion angle during UC TKAs. An inappropriate femoral rollback was identified, and femoral osteophyte formation was determined to be the most prominent in UC TKAs. Level of evidence Level III comparative study.

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The purpose of this study was to determine if significant clinical differences exist in patient-reported outcome measures (PROMs) between PS and CR TKAs implanted using robotic-assisted technology. This was an IRB-approved retrospective study from an institutional database evaluating 214 knees in 190 patients. Inclusion criteria included: primary RA-TKA, age 22-89 at the time of surgery, preoperative coronal limb deformity within 15º of neutral alignment, and minimum 1-year follow-up. The PS cohort consisted of 103 patients with 107 RA-TKAs, whereas the CR cohort consisted of 87 patients with 107 RA-TKAs. Cohorts were compared on the basis of demographics and PROMs (KSS knee, KSS function, FJS-12, KOOS-JR, WOMAC, and 5-point satisfaction Likert scale) collected preoperatively and at 1-year follow-up. Statistical analyses comparing measures were conducted via Student's t tests for continuous data and Chi-squared analyses for categorical data. There were no significant differences identified in short-term PROMs at 1-year follow-up between cohorts (all p values > 0.05). 93.1% of patients with CR knees and 94.7% of patients with PS knees reported a satisfaction level of "very satisfied" or "satisfied". Revision arthroplasty occurred in six knees (2.8%, 3 knees in CR cohort, 3 knees in PS cohort) with no differences in overall complications between groups. The use of RA-TKA technology promoted high patient satisfaction scores within this study, independent of CR or PS implant type with no significant differences in PROMs, satisfaction, revisions, or complications between the two groups.

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This study examined the influence of tibio-femoral conformity on anteroposterior (AP) knee stability during stair descent, particularly with a dished cruciate sacrificing (CS) design. A joint simulator simulated stair descent of cadaveric knees. Tibio-femoral displacement was measured. Knees were tested in intact, ACL-deficient, and TKA with cruciate-retaining (CR), CS and posterior-stabilizing (PS) inserts. Loading during stair descent simulation caused femur displacement anteriorly prior to quadriceps contraction. Quadriceps contraction reestablished the initial femoral AP position. During simulated stair descent, AP stability was restored using PS, CR or CS inserts with an intact PCL. The CS design without the PCL did not provide AP stability. Increasing quadriceps force to restore AP stability may explain the clinical findings of pain and fatigue experienced by some patients after TKA.

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BACKGROUND: Adjusting the joint gap length to be equal in both extension and flexion is an important issue in total knee arthroplasty (TKA). It is generally acknowledged that posterior tibial slope affects the flexion gap; however, the extent to which changes in the tibial slope angle directly affect the flexion gap remains unclear. This study aimed to clarify the influence of tibial slope changes on the flexion gap in cruciate-retaining (CR) or posterior-stabilizing (PS) TKA. METHODS: The flexion gap was measured using a tensor device with the femoral trial component in 20 cases each of CR- and PS-TKA. A wedge plate with a 5° inclination was placed on the tibial cut surface by switching its front-back direction to increase or decrease the tibial slope by 5°. The flexion gap after changing the tibial slope was compared to that of the neutral slope measured with a flat plate that had the same thickness as that of the wedge plate center. RESULTS: When the tibial slope decreased or increased by 5°, the flexion gap decreased or increased by 1.9 ± 0.6mm or 1.8 ± 0.4mm, respectively, with CR-TKA and 1.2 ± 0.4mm or 1.1 ± 0.3mm, respectively, with PS-TKA. CONCLUSIONS: The influence of changing the tibial slope by 5° on the flexion gap was approximately 2mm with CR-TKA and 1mm with PS-TKA. CLINICAL RELEVANCE: This information is useful when considering the effect of manipulating the tibial slope on the flexion gap when performing CR- or PS-TKA.

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