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BACKGROUND: A gradually reducing radius (GRADIUS) design implant can facilitate a smooth transition from stability through full range of motion in total knee arthroplasty (TKA). Nonetheless, patient-specific factors associated with good knee flexion remain unclear. OBJECTIVE: This study aimed to determine the factors associated with good knee flexion after cruciate-retaining TKA with a GRADIUS prosthesis in an Asian population. METHODS: This retrospective study included 135 patients that were stratified according to postoperative knee flexion angle (KFA) into Group F (⩾ 120∘; 85 patients [63.2%]) and Group NF (< 120∘; 50 patients [36.8%]). RESULTS: Patients in Group F were taller and had a lower body mass index (BMI) smaller preoperative hipkneeankle angle and better preoperative extension and flexion angle than Group NF patients. The multivariable analysis revealed that patients' height (odds ratio [OR]: 1.07, P = 0.0150), BMI (OR: 0.85, P = 0.0049), and preoperative flexion angle (OR: 1.06, P = 0.0008) predicted good KFA. The ROC curve analysis showed that the cutoff values of a good KFA were height 155.1 cm, BMI 22.1 kg/m2, and preoperative KFA 120∘. CONCLUSIONS: Patient height, BMI, and preoperative KFA were independent factors affecting good postoperative KFA in patients of Asian descent who underwent cruciate-retaining TKA with a GRADIUS design. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to clarify whether the range of motion (ROM), anterior and posterior (AP) stability and other clinical measures changed in patients who underwent tibia‐first total knee arthroplasty (TF‐TKA) using navigation with a computer‐aided system after surgery. Methods: This is a retrospective study and we conducted a matched cohort analysis of 60 measured resection (MR)‐TKAs and 52 TF‐TKAs performed by a single surgeon. All the surgeries used the same implant and approach. Baseline differences between the groups were adjusted using propensity score matching. We compared each patient's measured ROM and Oxford Knee Score (OKS) and performed knee AP laxity measurements by using a device during routine follow‐ups. Results: A total of 40 MR‐TKAs with a mean age of 73.5 ± 5.6 years and sex (male 10, female 30) were compared to 40 TF‐TKAs with a mean age of 74.0 ± 5.7 years and sex (male 13, female 27) at 2‐year follow‐ups. Two years postoperatively, there was a significant difference in the AP laxity at 30° of knee flexion between both groups (7.0 ± 3.4 mm vs. 5.2 ± 2.3 mm, p < 0.01). In contrast, no differences were found between both groups for knee flexion (120.8 ± 9° vs. 116.7 ± 9.8°, p = 0.07) and OKS score (41.8 ± 6.9 vs. 41.0 ± 5.9, p = 0.61). Conclusion: The AP stability in the midflexion obtained using the tibia‐first technique remained consistent even after 2 years. However, OKS and ROM were not significantly different from those of the MR‐TKA group. Level of Evidence: Retrospective comparative LEVEL III study. [ABSTRACT FROM AUTHOR]

BACKGROUND: Total knee arthroplasty (TKA) alleviates pain and improves daily living activities in individuals with end-stage osteoarthritis of the knee. However, up to 20% of patients have sub-optimal outcomes after TKA. OBJECTIVE: No studies have clarified the intraoperative factors that affect postoperative range of motion (ROM) after cruciate-retaining (CR) TKA. Thus, this study aims to clarify these factors. METHODS: Patients with knee osteoarthritis with varus knee deformity who underwent CR-TKA between May 2019 and December 2020 were included in this study. One year after surgery, patients were stratified into two groups based on knee flexion: Group F (over 120∘) and Group NF (below 120∘). Patient backgrounds including age, body mass index, hip knee angle, preoperative range of motion for both extension and flexion, intraoperative center joint-gap measurements of 0∘, 30∘, 45∘, 60∘, 90∘, and 120∘ of knee flexion using a tensor, intraoperative anterior-posterior (AP) laxity measurements of 30∘ and 90∘ of knee flexion using an instrumental laximeter were compared between the groups. Univariate analyses between the groups were used to construct the initial model. The receiver operating characteristic curve was also analyzed. The predictive variables included in the final model were selected by stepwise backward elimination. RESULTS: Intraoperative AP laxity with 30∘ of knee flexion smaller than 10.8 mm was a significant positive prognostic factor (OR: 1.39, 95% CI: 1.08–1.79, P = 0.011) of postoperative ROM over 120∘ of knee flexion one year after surgery. The sensitivity, specificity, PPV, and NPV were 70.9%, 82.4%, 92.9%, and 46.7%, respectively. CONCLUSION: Intraoperative AP laxity smaller than 10.8 mm was a significant positive predictive factor for obtaining knee flexion greater than 120∘ one year after surgery when using CR-TKA and its PPV was high up to 92.9%. [ABSTRACT FROM AUTHOR]

Prion diseases are fatal, transmissible neurodegenerative disorders characterized by deposition of abnormal prion protein ([PrP.sup.Sc]) in the brain (1). Human prion diseases, which include Creutzfeldt-Jakob disease (CJD), are classified into [...]