Maintenance of bone mineral density after implantation of a femoral neck hip prosthesis

<p>Abstract</p> <p>Background</p> <p>Stress shielding of the proximal femur has been observed in a number of conventional cementless implants used in total hip arthroplasty. Short femoral-neck implants are claiming less interference with the biomechanics of the proximal femur. The goal of this study was to investigate the changes of bone-mineral density in the proximal femur and the clinical outcome after implantation of a short femoral-neck prosthesis.</p> <p>Methods</p> <p>We prospectively assessed the clinical outcome and the changes of bone mineral density of the proximal femur up to one year after implantation of a short femoral neck prosthesis in 20 patients with a mean age of 47 years (range 17 to 65). Clinical outcome was assessed using the Harris Hip Score. The WOMAC was used as a patient-relevant outcome-measure. The bone mineral density was determined using dual energy x-ray absorptiometry, performed 10 days, three months and 12 months after surgery.</p> <p>Results</p> <p>The Harris Hip Score improved from an average preoperative score of 46 to a postoperative score at 12 months of 89 points, the global WOMAC index from 5,3 preoperatively to 0,8 at 12 months postoperatively. In contrast to conventional implants, the DEXA-scans overall revealed a slight increase of bone mineral density in the proximal femur in the 12 months following the implantation.</p> <p>Conclusion</p> <p>The short femoral neck stem lead to a distinct bone reaction. This was significantly different when compared to the changes in bone mineral density reported after implantation of conventional implants.</p

The Müller acetabular reinforcement ring - still an option in acetabular revision of Paprosky 2 defects? Longterm results after 10 years

Aim of this study was to measure the clinical and radiological longterm outcome after acetabular revision arthroplasty using the Müller acetabular reinforcement ring. 96 patients with 103 revision arthroplasties and a mean age of 69 years (41 to 84) were included. The mean follow-up was 10 years (range 7 – 12). The radiologic analysis reports no signs of loosening in 76 %, 17 % showed possibly loosening and 7 % probable loosening. Definite radiologic loosening has not been detected. The mean center of rotation of the hip moved 0.15 cm (SD 0.74 cm) laterally and 0.1 cm (SD 0.97 cm) cranially based on the geometrically reconstructed center of rotation. A mean score of 58 points for the Harris Hip Score (range 14 – 93) indicated a poor functional outcome, while a mean value of 96 points (range 0 – 223) for the WOMAC Index indicated good results for functional outcome in daily living. The revision arthroplasty in cases with acetabular defects using the Müller acetabular reinforcement ring shows acceptable longterm results

Long Pulse Kicker for European XFEL Beam Distribution

A special feature of the European XFEL X-ray laser is the possibility to distribute the electron bunches of one beam pulse to different free-electron laser (FEL) beam-lines. This is achieved through a combination of kickers and a Lambertson DC septum. The integration of a beam abort dump allows a flexible selection of the bunch pattern at the FEL experiment, while the superconducting linear accelerator operates with constant beam loading. The driver linac of the FEL can deliver up to 600 µs long bunch trains with a repetition rate of 10 Hz and a maximum energy of 17.5 GeV. The FEL process poses very strict requirements on the stability of the beam position and hence on all upstream magnets. It was therefore decided to split the beam distribution system into two kicker systems, long pulse kickers with very stable amplitude (flat-top) and relatively slow pulses and fast stripline kickers with moderate stability but very fast pulses. This contribution gives a brief overview of the long pulse kicker system

Fast Kicker System for European XFEL Beam Distribution

A special feature of the European XFEL X-ray laser is the possibility to distribute the electron bunches of one beam pulse to different free-electron laser (FEL) beam-lines. This is achieved through a combination of kickers and a Lambertson DC septum. The integration of a beam abort dump allows a flexible selection of the bunch pattern at the FEL experiment, while the superconducting linear accelerator operates with constant beam loading. The driver linac of the FEL can deliver up to 600 µs long bunch trains with a repetition rate of 10 Hz and a maximum energy of 17.5 GeV. The FEL process poses very strict requirements on the stability of the beam position and hence on all upstream magnets. It was therefore decided to split the beam distribution system into two kicker systems, long pulse kickers with very stable amplitude (flat-top) and relatively slow pulses and fast stripline kickers with moderate stability but very fast pulses. This contribution gives a brief overview of the fast kicker system

Multi-Beamline Operation at the European XFEL

The European XFEL uses a unique beam distribution scheme to direct electron bunches to its three undulator lines.The accelerator delivers up to 600 microsecond long bunchtrains, out of which parts or individual bunches can be selectedfor photon production in any of the FELs. This contribution gives a brief overview of the kicker-septum scheme facilitating this and highlights how even complex bunch patterns can easily be configured via the timing system