The Journal of arthroplasty
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Secure fixation of acetabular components in total hip arthroplasty can be challenging. The purpose of this study was to perform biomechanical analysis of cup fixation strength using fixed-angle vs standard screw fixation. Multihole, porous-backed acetabular prostheses were implanted in both acetabuli of 8 cadaveric pelves using standard press-fit techniques. ⋯ The use of fixed-angle screws enhanced acetabular fixation substantially under subfailure cyclic loading conditions and load-to-failure. The triradiate screw configuration increases the bending moment required to fail the specimens as well. Fixed-angle screws may be useful for achieving rigid fixation of acetabular prostheses in challenging clinical scenarios.
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An institutional review board-approved retrospective review of hip fractures in elderly patients treated with a modular unipolar implant was carried out to identify factors predisposing to dislocation of a hemiarthroplasty. The main outcome measure evaluated was dislocation vs nondislocation. Two hundred seventeen patients underwent the surgery, and 174 were available for review at 6 weeks and 144 at 1 year. ⋯ Radiographic factors in dislocated hips included a smaller femoral neck and contralateral femoral neck offset. The center edge angle was also smaller in the dislocated patients. These patients had a higher mortality rate.
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Randomized Controlled Trial
Single-injection femoral and sciatic nerve blocks for pain control after total knee arthroplasty.
This study was designed to evaluate the addition of a single-injection sciatic nerve block to a femoral nerve block for analgesia after total knee arthroplasty. Fifty-seven patients undergoing primary total knee arthroplasty were randomized to receive femoral nerve blockade or a sham block. A subsequent 31 patients received both femoral and sciatic nerve blocks (FSNBs) before general anesthesia. ⋯ Lower visual analog pain scale scores were noted in both femoral nerve blockade and FSNB groups compared to shams through 48 hours. Morphine use was significantly lower in the FSNB group. Femoral and sciatic nerve block can be placed quickly and consistently in the operating room with improved postoperative pain relief and reduced narcotic consumption.
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We analyzed the National Hospital Discharge Survey to elucidate temporal changes in the demographics, comorbidities, hospital stay, in-hospital complications, and mortality of patients undergoing primary total knee arthroplasties (TKAs) in the United States. Three 5-year periods were created (1990-1994, 1995-1999, and 2000-2004), and temporal changes were analyzed. The number of TKAs performed increased by 125% for the 3 periods. ⋯ Although the prevalence of procedure-related complications decreased over time, comorbidities increased. Despite a decrease in mortality from the first to the second study period (0.50% vs 0.21%), a slight increase was noticed more recently (0.28%). We identified significant changes in most variables studied.
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The aim of the study is to explore the impact of storage time on wear rates. Two groups of acetabular liners with a storage time of 1 and 4 years were tested on 2 hip simulators of the same type. There were 6 liners in each group. ⋯ The mean wear rate for the group of 4-year-old liners (36.3 mg/million cycles) was significantly higher than that for the 1-year-old group (23.1 mg/million cycles) (P < .05). After the last gravimetric analysis, scanning electron microscopy was used to observe the wear patterns of the bearing surfaces. This study found that wear resistance decreased as storage time increased.