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Background: The purpose of this study was to evaluate the joint gap kinematics in posterior-stabilized total knee arthroplasty (PS TKA).Methods: Between January 2010 and April 2011, 44 consecutive patients (55 knees) who underwent primary PS TKA using the navigation system were assessed. There were 37 women and 7 men with a mean age at operation of 63 years (range; 58-73 years). After fixation of all components with cement and insertion of polyethylene trial insert, medial and lateral joint gap measurements were carried out without distraction force and separately using a navigation system on each flexion angles. The joint gaps were measured before and after deflation of tourniquet, first with patella everted and then reduced.Results: Deflation of tourniquet did not effect on gap. In patellofemoral joint reduction situation, the medial gap relatively maintained throughout the range of knee motion, but the lateral gap is gradually decreasing with knee flexion from 30° to 120° flexion. However, in patellar eversion situation, the medial gap showed a significant increase and also statistically significantly increased compared with patellar reduced position over 90° knee flexion status, but the lateral gaps are decreased compared with patellofemoral reduction situation throughout the range of knee motion except full flexion status. In more physiologic status that is patella reduced and tourniquet deflated status, the average medial joint gap change was 2.30 ± 1.64 mm and the average lateral joint gap change was 2.90 ± 1.53 mm throughout the range of motion.Conclusions: Medial and lateral joint gaps showed different patterns with patellar eversion and patellofemoral joint reduction. However, such changes occurred within 3 mm in average throughout whole range of knee motion even with multi-radius femoral component. [ABSTRACT FROM AUTHOR]

Purpose: To compare the radiographic migration profiles of primary cementless total hip arthroplasty (THA) between patients with rheumatoid arthritis (RA) and those with osteoarthritis (OA).Methods: A total of 197 patients (215 hips) who underwent cementless THA for RA or OA between January 2001 and January 2013 and followed up for a minimum of 5.5 years were included. Ninety-four RA patients (109 hips) were compared with 103 OA patients (106 hips). Radiological evaluation was performed for acetabular cup loosening, and cup migration was measured using Einzel-Bild-Röntgen-Analyse (EBRA) software. Multiple variables were assessed to identify influencing factors for cup migration.Results: Early cup migration was observed in 13 hips (11.9%) in the RA group and four hips (3.8%) in the OA group, showing a significant difference (p = 0.041). Acetabular cup loosening occurred in three cups (2.8%) in the RA group and in one cup (0.9%) in the OA group, showing no significant difference (p = 0.321). Total cup migration was higher in the RA group (2.62 mm) than in the OA group (1.44 mm, p = 0.005). Total cup migration was significantly higher in patients aged < 50 years than in those aged > 50 years (p = 0.005). Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody influenced total cup migration. Patients with seropositive RA showed significantly higher total cup migration and early cup migration incidence than those with seronegative RA (p = 0.005, p = 0.038, respectively).Conclusions: Acetabular cups in primary cementless THAs of RA patients were less stable in terms of cup migration compared with that of OA patients. [ABSTRACT FROM AUTHOR]

Purpose: Neuromuscular disease is well known to be at increased risk of complications following hip replacement surgeries. This study is prospectively conducted to investigate clinical performance and survivorship of total hip arthroplasty (THA) using dual mobility articulation in femoral neck fractures of elderly with neuromuscular disease.Materials and Methods: We prospectively enrolled 162 patients (162 hips) with displaced femoral neck fracture who gave informed consent for dual mobility articulation THA. Of the 162 patients, 35 patients had neuromuscular disease including cerebral palsy, poliomyelitis, hemiplegia, and Parkinson disease (NM group). The other 127 patients had no history of neuromuscular disease (non-NM group). The mean age was 76.5 years (range, 60 - 95) and female ratio was 71.0% (115/162). Clinical outcomes including Harris hip score (HHS), University of California Los Angles activity (UCLA) score were compared between the two groups. Computed tomography and serial radiographs were obtained after surgery. Postoperative complications and reoperation including revision were recorded.Results: Pain-VAS and all clinical scores of the NM group were comparable to those of the non-NM group. The incidence of dislocation in the NM group did not differ from that in Non-NM group (2/35, 5.7% versus 5/127, 3.9%, p = 0.645). Reoperation was performed in 3 hips (3/35, 8.6%) of the NM group and in 4 hips (4/127, 3.1%) of the non-NM group (p = 0.173). Kaplan-Meier survivorship with an end point of revision for any reason was 97.1% (95% confidence interval [CI], 0.92 to 1.03) in the NM group and 98.4% (95% CI, 0.96 to 1.01) in the non-NM group at 7.3 years after surgery.Conclusions: In elderly with neuromuscular disease, THA with dual mobility articulation is a reasonable option as a treatment for femoral neck fractures. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to investigate the incidence of dislocation and specific complications of the dual-mobility cup.Methods: The arthroplasties involved 167 hips in 165 patients; 51 hips (30.5%) were in men and 116 (69.4%) were in women. The active articulation E1® dual-mobility cup (Biomet, Warsaw, IN, USA) was used, and the surgical approach was posterolateral in 120 hips and anterolateral in 47 hips.Results: Four (2.3%) dislocations were observed. Mean time of dislocation was 30.5 days post-operatively. Three incomplete reductions occurred during closed reduction. When comparing parameters between dislocation and no-dislocation groups, there were no differences in patient and surgical parameters. However, all dislocations occurred in patients with femoral neck fractures and in the posterolateral approach group.Conclusion: The incidence of dislocation in total hip arthroplasty (THA) using a dual-mobility cup was acceptable, and cup diameter of the dislocation group was substantially larger than that of no-dislocation group. Based on clinical outcomes of our study, we conclude that the dual-mobility cup is a reliable option in THA, and further studies are necessary. [ABSTRACT FROM AUTHOR]