The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Olufemi R Ayeni - One of the best experts on this subject based on the ideXlab platform.
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press fit fixation in anterior cruciate ligament reconstruction yields low graft failure and revision rates a systematic review and meta analysis
Knee Surgery Sports Traumatology Arthroscopy, 2020Co-Authors: Ajaykumar Shanmugaraj, Mathepan Mahendralingam, Chetan Gohal, Nolan S Horner, Nicole Simunovic, Volker Musahl, Kristian Samuelsson, Olufemi R AyeniAbstract:Press-fit fixation is a hardware-free technique in anterior cruciate ligament reconstruction (ACLR). The purpose of this review was to quantitatively assess the risk profile and outcomes of press-fit fixation and provide an update on its effectiveness compared to more standard fixation techniques of ACLR. The electronic databases PUBMED, MEDLINE, and EMBASE were searched on March 26, 2020 for therapeutic randomized controlled trials (RCT) addressing press-fit fixation for primary ACLR. The Grading of Recommendations Assessment, Development and Evaluation tool was used to assess the quality for randomized studies. A meta-analysis with a random-effects model was used to pool applicable outcomes data. A total of six eligible RCTs were included in this review. There were 292 patients (72.9% male) with a mean age of 28.8 ± 3.8 years and a mean follow-up of 81.3 ± 88.3 months that underwent press-fit ACLR on the femoral, tibial or both tunnels. Femoral fixation techniques included press-fit fixation (96.6%) and cross-pin fixation (3.4%). Tibial fixation techniques included press-fit (37.0%), staples (28.1%), interference screws (21.2%) and abarticular post-screws (13.7%). Graft options included bone–patellar tend–-bone autografts (73.6%) and semitendinosus and gracilis tendon autograft (26.4%). Significant improvements (p < 0.05) from baseline to follow-up were found for clinical outcomes. Significantly less postoperative bone tunnel enlargement (p < 0.05) was found with tibial press-fit fixation when compared to biodegradable screws. The overall complication rate was 13.3%. There were no significant differences in complication rates [odds ratio = 0.84 (95%CI 0.43–1.66); p = n.s.] (I2 = 0%) between patients undergoing femoral press-fit fixation and femoral metal interference screw fixation. The overall graft failure and revision rates with press-fit ACLR were low. There were no significant differences in complication rates between patients undergoing femoral press-fit and femoral metal interference screw fixation. Included studies found that patients undergoing press-fit fixation for ACLR had significant improvements in functional outcome scores postoperatively and had significantly reduced postoperative bone tunnel enlargement compared to patients undergoing bioabsorbable fixation. Thus, early evidence suggests that press-fit fixation appears to be a good option for patients undergoing ACLR. I.
Evan Lederman - One of the best experts on this subject based on the ideXlab platform.
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short term evaluation of humeral stress shielding following reverse shoulder arthroplasty using press fit fixation compared with cemented fixation
Journal of Shoulder and Elbow Surgery, 2020Co-Authors: Patrick J Denard, Georges Haidamous, Anthony A. Romeo, Reuben Gobezie, Evan LedermanAbstract:Background The purpose of this study was to compare the functional outcomes and humeral stress shielding of a reverse shoulder arthroplasty (RSA) placed with either cement or press-fit fixation. The hypothesis was that there would be no difference in functional outcomes or stress shielding. Methods We performed a multicenter retrospective review of primary RSAs performed with standard-length stems. The stems were identical in geometry and coating with the only variable being whether the stems were secured with cement or by a press-fit technique. The functional outcomes and radiographs of 93 press-fit stems and 26 cemented stems were reviewed at a minimum of 2 years postoperatively. Results Significant improvements were noted in all ranges of motion and functional outcomes from baseline (P .05). Calcar osteolysis was seen in 43% of press-fit and 58% of cemented stems (P = .266). Proximal lateral stress shielding was more common in the press-fit group (68%) than in the cemented group (25%) (P = .045). Adaptive changes were considered low in 97% of press-fit stems, and there were no cases of tuberosity resorption. No evidence of loosening or humeral component shift was noted in either group. Conclusion At short-term follow-up, no differences in functional outcomes or stem loosening were found between press-fit fixation and cemented fixation of an RSA humeral stem. Proximal stress shielding was more common with press-fit fixation with the stem in this study, but the overall changes were considered low in 97% of cases. Further study is needed to evaluate the mid- to long-term differences regarding stress shielding.
Daniel Casellas - One of the best experts on this subject based on the ideXlab platform.
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effect of the cutting process on the fatigue behaviour of press hardened and high strength dual phase steels
Journal of Materials Processing Technology, 2013Co-Authors: A Lara, I Picas, Daniel CasellasAbstract:Abstract Press hardened 22MnB5 steels are steady broadening their applications in vehicles since they allow to meet the increasing demands for weight reduction and safety standards. Press hardened parts have been typically applied as structural reinforcements where high rigidity and crash resistance are required. However, the need for further weight reductions in vehicles leads to potential applications in chassis areas, where parts must face up to cyclic loads. The fatigue behaviour of the press hardened 22MnB5 steel and the effect that post-forming processes (such as trimming or punching that usually follows press hardening) on the fatigue behaviour is scarcely known. Thus, the aim of this work is to analyse the fatigue behaviour of 22MnB5 press hardened steels cut using different strategies. The fatigue limit has been obtained in tensile samples of 22MnB5 with an Al–Si coating. Samples were cut by laser and shearing with two different clearance values. Results are compared to those obtained with a high drawing quality mild steel and a dual phase steel with a tensile strength of 1000 MPa, DP1000. It is shown that the fatigue behaviour of press hardened 22MnB5 steels and DP1000 is governed by the defects introduced in cut edges, while the behaviour of the mild steel is almost independent of the cut edge quality. This finding indicates that high strength steels are markedly sensitive to pre-existent defects, such as burr, cracks at the cut edge or surface cracks, and they can be considered as low damage tolerant steels. On the contrary, mild steels are highly damage tolerant, i.e. the fatigue life is mainly independent of the initial defect size. In press hardened 22MnB5, even when cut edges have a high surface quality, the fatigue limit is still limited by the presence of cracks in the brittle Al–Si coating. Crack propagation due to the low damage tolerance capacity of the press hardened steel has been successfully rationalized through a fracture mechanics approach. Thus, if coated press hardened 22MnB5 steels are to be applied in vehicle components subjected to cyclic loads, they must be designed following fracture mechanics concepts to state the safe loading conditions for adequate fatigue resistance.
William H Harris - One of the best experts on this subject based on the ideXlab platform.
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factors influencing stability at the interface between a porous surface and cancellous bone a finite element analysis of a canine in vivo micromotion experiment
Journal of Biomedical Materials Research, 1997Co-Authors: Balaji S Ramamurti, Tracy E Orr, Charles R Bragdon, Jay D Lowenstein, Murali Jasty, William H HarrisAbstract:Several factors contribute to the success of stable bony ingrowth into the porous coated surfaces of orthopaedic implants used in hip arthroplasty. Despite having good bony apposition, bony ingrowth might not occur if the relative motion between bone and implant is large. Therefore, determining the limiting micromotion value that inhibits stable bony ingrowth is important. From a previous canine in vivo micromotion study performed at our laboratory, this limiting value was found to be 20 μm. Initially, cementless orthopaedic implants are stabilized only by frictional forces at the bone-implant interface. Therefore, other parameters such as the coefficient of friction and the compressive force normal to the interface should be considered as important factors which stabilize the interface along with micromotion. The purpose of this analytical study was to elucidate how the stability at the bone-implant interface is influenced by various factors, namely, motion of the implant, the coefficient of friction, the degree of press fit, and the modulus of the surrounding cancellous bone in determining the stability of the bone-implant interface. Nonlinear and linear finite element models which simulated the immediate postsurgical condition and the end point of the canine in vivo micromotion experiment, respectively, were used to this end. From the results of the finite element models it was possible to identify the displacement magnitude for which the implant slipped relative to the bone as the motion of the implant was increased incrementally. This was done for combinations of the coefficient of friction, press fit, and Young's modulus of cancellous bone. This was used as an indicator of the limiting implant motion value beyond which bony ingrowth will be inhibited. The stress distribution in the surrounding cancellous bone bed was also obtained from the results of the finite element analyses for different press-fit conditions. The results of the study indicated that under slight press-fit conditions, the implant slipped relative to bone for implant motions as low as 20 μm. For higher degrees of press fit and reasonable values for the coefficient of friction, no slip occurred for implant motions as much as 100 μm. Although higher degrees of press fit were theoretically conducive to better implant stability, the concomitant high stresses in the adjacent cancellous bone will tend to compromise the integrity of the press fit. This was also evident when the results of an analytical model with a lower degree of press fit correlated well with those of the canine in vivo experiment in which a higher press fit was used, suggesting a possibility of achieving a less than desired press fit during the process of implantation. Through this study the importance of factors other than implant motion was emphasized. The results of the study suggest that the limiting value of implant motion that inhibits bone ingrowth might vary with the degree of press fit for reasonable coefficients of friction. © 1997 John Wiley & Sons, Inc. J. Biomed Mater Res, 36, 274–280, 1997.
A Van Droogenbroeck - One of the best experts on this subject based on the ideXlab platform.
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a comparative study between spiral filter press and belt press implemented in a cloudy apple juice production process
Food Chemistry, 2015Co-Authors: Domie De Paepe, Katlee Coudijze, A Note, Dirk Valkenborg, Kelly Servaes, Marc De Loose, Ludo Diels, Stefa Voorspoels, A Van DroogenbroeckAbstract:Abstract In this study, advantages and disadvantages of the innovative, low-oxygen spiral-filter press system were studied in comparison with the belt press, commonly applied in small and medium size enterprises for the production of cloudy apple juice. On the basis of equivalent throughput, a higher juice yield could be achieved with spiral-filter press. Also a more turbid juice with a higher content of suspended solids could be produced. The avoidance of enzymatic browning during juice extraction led to an attractive yellowish juice with an elevated phenolic content. Moreover, it was found that juice produced with spiral-filter press demonstrates a higher retention of phenolic compounds during the downstream processing steps and storage. The results demonstrates the advantage of the use of a spiral-filter press in comparison with belt press in the production of a high quality cloudy apple juice rich in phenolic compounds, without the use of oxidation inhibiting additives.