BACKGROUND:Posterior stabilized femoral knee prosthesis needs additional condyle osteotomy to accommodate the tibial post and femur fossa structures. Intercondylar fossa on both sides connected at the femoral body with concentrated stress is a place easily affecting fractures. Differences in bone mass between different models of different brands did not have specific data, which was not convenient to select prosthesis for clinicians.
OBJECTIVE: To compare the difference of intercondylar osteotomy data among clinical commonly used posterior stabilized knee prostheses (six imported and domestic brands), and to provide basis for the selection and application of the prostheses.
METHODS:The current commonly used posterior stabilized knee prostheses (six imported and domestic brands) were used, including Zimmer NexGen LPS, Stryker Scrorpio NRG Knee-Flexed, Depuy PFC Sigma, Smith & nephew Genesis-2 PS, United-U1 and Wego GKPS. According to the osteotomy template, the osteotomy-surfaces consisting of femoral condyle starting section and cross section, distal section of femoral condyle, and back-oblique section were identified. The corresponding femoral prosthesis diameter lines included condylar ambilateral and anteroposterior diameters, width and depth of femoral intercondylar fossa. The above data were compared and measured.
RESULTS AND CONCLUSION:The six kinds of knee femoral prostheses were different in ratio of ambilateral diameter and anteroposterior diameter, bone resection of intercondylar fossa, and geometry. Imported prostheses carry shorter diameters in femoral starting and cross sections, so it can catch more posterior condylar osteotomy. With increasing prosthesis sizes, the ratio of bone loss causing by width of intercondylar osteotomy is decreased among six brands. In al sizes, Stryker Scrorpio NRG Knee-Flexed catches shorter width of intercondylar osteotomy. Knee prosthesis osteotomy among six brands is different. The result of this study is not sufficient to evaluate the pros and cons between different prostheses, but as reserving bone is concerned, the design of less intercondylar osteoomy catches more advantages.

Objective: To investigate the microbiological test, antibiotic sensitivity and surgical treatment of periprosthetic joint infection(PJI) cases in post total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients. Methods: A retrospective cross-sectional survey was conducted on 318 patients who underwent THA or TKA in 9 clinical centers in Beijing from January 2014 to December 2016.The data of microbiology, antibiotic sensitivity and surgical treatment were collected.The average age of patients was (62.3±13.1) years old (range: 21-86 years old), including 145 males and 173 females.The body mass index was (25.6±3.8) kg/m ² (range: 15.6-38.1 kg/m²). Results: In total, 318 patients had microorganisms detected by periprosthetic tissue culture or synovial fluid culture, 209 cases (65.7%) had Gram-positive bacteria, 29 cases (9.1%) had Gram-negative bacteria, 10 cases (3.1%) had fungi, 3 cases (0.9%) had non-tuberculous mycobacteria, 72 cases (22.6%) were negative, 69 cases (21.7%) had methicillin-resistant bacteria. The antibiotic sensitivity results showed that the overall resistance rate of penicillin, cefuroxime, amoxicillin+clavulanic acid was 79.9%, 69.9%, and 68.1%, respectively; meropenem, vancomycin, and linezolid resistance rate was 0. For the treatment methods of hip and knee PJI, two-stage revision surgery acounted for 72.9% (108/148) and 64.1% (109/170), respectively. One-stage revision surgery accounted for 21.6% (32/148) and 7.6% (13/170), and open debridement surgery accounted for 4.7%(7/148) and 26.4% (45/170). Conclusions Gram-positive bacteria was still the main pathogen of PJI.The methicillin-resistant bacteria and rare bacteria should be payed attention to. The Majority of hip and knee PJI cases were treated by two-stage revision surgery.