Radiopacity and fatigue characterization of a novel acrylic bone cement with sodium fluoride

Acrylic bone cement must provide good radiographic visibility and good long-term mechanical resistance in joint replacements. A new formulation of cement with 6% barium sulfate and 6% sodium fluoride was developed (Fluoride Bone Cement). Barium sulfate is a necessary addition to allow radiographic visibility although it reduces the mechanical strength of the material. Sodium fluoride promotes bone formation. However, its effect on the mechanical behavior is currently unknown while its influence on radiopacity can only be roughly estimated. The aim of this investigation was to establish if the new formulation would be suitable for clinical trials. In this respect, a mechanical (fatigue test) and radiographic (optical density measurements on x-ray films) characterization was performed on a typical commercially available cement with barium sulfate added and on the Fluoride Bone Cement. It was demonstrated that the fluoride cement has a (marginally) superior fatigue strength and comparable radiopacity to commercial radiopaque cements.     

The genetic influence on bone susceptibility to fluoride

INTRODUCTION: The influence of genetic background on bone architecture and mechanical properties is well established. Nevertheless, to date, only few animal studies explore an underlying genetic basis for extrinsic factors effect such as fluoride effect on bone metabolism. MATERIALS AND METHODS: This study assessed the effect of increasing fluoride doses (0 ppm, 25 ppm, 50 ppm, 100 ppm) on the bone properties in 3 inbred mouse strains that demonstrate different susceptibilities to developing enamel fluorosis (A/J a "susceptible" strain, 129P3/J a "resistant" strain and SWR/J an "intermediate" strain). Fluoride concentrations were determined in femora and vertebral bodies. Bone mineral density was evaluating through DEXA. Finally, three-point bend testing of femora, compression testing of vertebral bodies and femoral neck-fracture testing were performed to evaluate mechanical properties. RESULTS: Concordant with increasing fluoride dose were significant increases of fluoride concentration in femora and vertebral bodies from all 3 strains. Fluoride treatment had little effect on the bone mineral densities (BMD) in the 3 strains. Mechanical testing showed significant alterations in "bone quality" in the A/J strain, whereas moderate alterations in "bone quality" in the SWR/J strain and no effects in the 129P3/J strain were observed. CONCLUSION: The results suggest that genetic factors may contribute to the variation in bone response to fluoride exposure and that fluoride might affect bone properties without altering BMD.     

Orthopaedic bone cement: do we know what we are using?

Bone cements produced by different manufacturers vary in their mechanical properties and antibiotic elution characteristics. Small changes in the formulation of a bone cement, which may not be apparent to surgeons, can also affect these properties. The supplier of Palacos bone cement with added gentamicin changed in 2005. We carried out a study to examine the mechanical characteristics and antibiotic elution of Schering-Plough Palacos, Heraeus Palacos and Depuy CMW Smartset bone cements. Both Heraeus Palacos and Smartset bone cements performed significantly better than Schering-Plough Palacos in terms of mechanical characteristics, with and without additional vancomycin (p < 0.001). All cements show a deterioration in flexural strength with increasing addition of vancomycin, albeit staying above ISO minimum levels. Both Heraeus Palacos and Smartset elute significantly more gentamicin cumulatively than Schering-Plough Palacos. Smartset elutes significantly more vancomycin cumulatively than Heraeus Palacos. The improved antibiotic elution characteristics of Smartset and Heraeus Palacos are not associated with a deterioration in mechanical properties. Although marketed as the 'original' Palacos, Heraeus Palacos has significantly altered mechanical and antibiotic elution characteristics compared with the most commonly-used previous version.     

Laser ablation of dyed acrylic bone cement

Revision surgery of cemented implants is indicated when mechanical failure causes severe pain and/or loss of function for the patient. Successful revision arthroplasty of cemented implants requires complete removal of the existing cement. Removal of old cement is an arduous task often causing damage to the surrounding bone tissue. In this study, the authors investigate the use of an Argon laser and the addition of dyes to enhance the laser ablation of bone cement. Methylene blue and red dye #13 were each added separately to polymethylmethacrylate (PMMA) bone cement powder. A continuous wave Argon ion laser (λ = 514 nm) was used for cement ablation. Cement samples were ablated at different power levels (1.5, 2.3, and 3.0 W) and exposure times (30, 60, 90, 120 sec). The results show that the Argon laser was unable to ablate undyed PMMA. However, the addition of either methylene blue or red dye #13 greatly improved cement ablation by altering the cements' absorption characteristics. Results of Student's t-tests show a statistical difference between red and blue dyed PMMA mean ablation areas at all energy levels tested (P < .0002). As expected, all red ablation areas were greater than blue ablation areas at each energy level tested since red dye absorbs more energy at 514 nm than methylene blue dye. The results of this study suggest that by selectively altering the absorption characteristics of PMMA, laser removal of bone cement can be achieved. In addition, this study also shows that bone tissue does not absorb visible light energy at 514 nm, suggesting that bone cement may be removed with minimal damage to the surrounding bone tissue. Lasers Surg. Medicine 20:280–289, 1997. © 1997 Wiley-Liss, Inc.     

The effect of fluoride on bone of rats fed diets deficient in calcium or phosphorus

Four groups of weanling rats were fed for 2 weeks on a diet sufficient or insufficient in calcium and/or phosphorus. Each group was divided into four subgroups which were offered distilled water supplemented with 0, 50, 75, or 150 ppm fluoride. High levels of fluoride in drinking water inhibited weight gain. This inhibition was less in rats deficient in phosphorus than when normal-phosphorus diets were offered.At a low level, fluoride was without any effect on bone ash, thickness of femoral cortical bone, and mechanical strength, as measured by maximal load, ultimate stress to breaking, and limit of elasticity. Modulus of elasticity was decreased. At higher levels fluoride tended to decrease most of these parameters, except in rats deprived of both calcium and phosphorus.The effect of fluoride was modified by lack of dietary calcium and/or phosphorus and appeared to be weaker in rats deficient in these nutrients. Lack of dietary calcium and/or phosphorus decreased bone strength more than did fluoride content of water and of bone mineral.Concentration of bone ash and thickness of femoral cortical bone were closely correlated with parameters of mechanical strength.     

Peri‐implant stress correlates with bone and cement morphology: Micro‐FE modeling of implanted cadaveric glenoids

Aseptic loosening of cemented joint replacements is a complex biological and mechanical process, and remains a clinical concern especially in patients with poor bone quality. Utilizing high resolution finite element analysis of a series of implanted cadaver glenoids, the objective of this study was to quantify relationships between construct morphology and resulting mechanical stresses in cement and trabeculae. Eight glenoid cadavers were implanted with a cemented central peg implant. Specimens were imaged by micro‐CT, and subject‐specific finite element models were developed. Bone volume fraction, glenoid width, implant‐cortex distance, cement volume, cement–cortex contact, and cement–bone interface area were measured. Axial loading was applied to the implant of each model and stress distributions were characterized. Correlation analysis was completed across all specimens for pairs of morphological and mechanical variables. The amount of trabecular bone with high stress was strongly negatively correlated with both cement volume and contact between the cement and cortex (r = ?0.85 and ?0.84, p < 0.05). Bone with high stress was also correlated with both glenoid width and implant‐cortex distance. Contact between the cement and underlying cortex may dramatically reduce trabecular bone stresses surrounding the cement, and this contact depends on bone shape, cement amount, and implant positioning. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1671–1679, 2015.

     

The morphology of polymethylmethacrylate (PMMA) bone cement: surface structures and causes of their origin

This study deals with the correlation between the polymerizing bone cement and the surrounding tissue. The surface structures of bone cements, polymerized in air, in tissue medium (in vitro) and in human bone during implantation were investigated and compared with the contours of the tissue of the implant bed. Basing on the dimensional differences it was differentiated between contours of 1st order and 2nd order: contours of 1st order are within the macroscopic range, contours of 2nd order within the microscopic range. The surface of bone cement polymerized in living human tissue differed essentially from samples polymerized under laboratory conditions. The differences are to be seen macroscopically in the coarse relief as well as microscopically in the shape and the connection of the superficial methylmethacrylate beads. Bone cements, polymerized in air show an ideal, even and closed surface. Bone cements, polymerized in tissue medium exhibit macroscopically some wrinkles, in the microscopic range their contours are either closed (samples prepolymerized at 22 degrees C) or partly open and partly closed (samples prepolymerized at 24 degrees C). The surface of bone cement implants, retrieved from human bones are characterized macroscopically by a marked wrinkled and papillary relief, microscopically by flattened beads, and most often by an irregular, rough and open surface with isolated beads giving almost the impression of a porous surface structure. The character of the surface of the bone cement originates from external, mechanical influences, from changes in the volume of the bone cement and from effects of the surrounding tissues. The surface of the bone cement implanted in human bone conforms exactly with the contour of the adjacent tissue; the tissue contour is infact a negative of the cement surface. The incomplete connection between the superficial PMMA beads seems to be of some practical value: In areas, where the PMMA beads are largely isolated, the mechanical stressability of the "polymer composite" is relatively low. Under high load, beads and bead-clusters may break off the surface. Shattering of bone cement implants possibly may start from such an open, porous surface area where PMMA beads are extensive isolated.     

Fluoride-containing acrylic bone cement in total hip arthroplasty. Randomized evaluation of 97 stems using radiostereometry and dual-energy x-ray absorptiometry

Ninety patients (97 hips) scheduled for total hip arthroplasty were stratified to fixation of the femoral component using fluoride-containing cement or Palacos with gentamicin. Whole polyethylene Reflection and press-fit Trilogy cups were used. All patients received Spectron EF stem. The micromotions of the stem were measured with radiostereometric analysis and the periprosthetic bone mineral density with automatic and manual dual-energy x-ray absorptiometry (DEXA) analysis. At 2 years, the choice of cement did not influence the subsidence or rotations of the stem. The DEXA analysis revealed more loss of periprosthetic bone mineral density in fluoride cement group. We speculate that forming of fluorapatite crystals, toxic effects of the fluoride, or lower radiopacity of the fluoride cement might explain this finding. According to our study with 2-year of follow-up, there is no obvious advantage of addition of fluoride to acrylic bone cement when used to fixate the femoral component in total hip arthroplasty.     

Osteolysis in alloarthroplasty of the hip. The role of bone cement fragmentation

Movement at the interface between bone and cement and fractures of the cement can cause fragmentation of the polymethylmethacrylate (PMMA) bone cement implant. In order to obtain further information about the effect of PMMA fragments on the surrounding tissue and the role of such particles in the development of bone resorption, the authors investigated 17 patients with cemented total hip endoprostheses showing osteolysis and implant loosening in the femoral shaft with (Group B) and without (Group A) involvement of the acetabulum. The roentgenographic follow-up examinations revealed an initially slow and later more rapid extension of the endosteal bone erosions, with a predilection for the tip of the stem, the lesser trochanter, and laterally for the middle of the stem. At revision surgery, tissue samples were taken from the joint capsule and the bone-cement interface, in particular from the osteolysis in the femoral shaft and the acetabulum. The tissue samples were processed for histology, microscopically examined, and semiquantitatively evaluated. The retrieved devices were also carefully inspected. Large foreign-body granulomas were found at the bone-cement interface and in the joint capsule. Histiocytes and foreign-body giant cells stored particles of PMMA and polyethylene, of which fragmented bone cement predominated. Granulomatous tissue invaded bone canals and marrow spaces and induced resorption of the surrounding bone. In four cases in Group A, tissue from the osteolysis contained only fragmented bone cement, demonstrating that PMMA particles alone may be responsible for triggering focal bone resorption. Osteolysis seems to begin at the site where disintegration of bone cement begins. In cases in which polyethylene particles were found in the tissue in addition to fragmented bone cement, wear from the ultrahigh molecular weight polyethylene socket has been increased by entrapment of PMMA particles between the joint surfaces. Thus, fragmentation of bone cement and abrasion of polyethylene enhance each other. Bone cement particles promote polyethylene wear, which in turn promotes granuloma formation, bone resorption, and subsequent bone cement disintegration.     

骨水泥强化椎弓根钉与否治疗退变性腰椎疾患临床分析

目的通过临床对骨水泥强化椎弓根钉与否术后病人的疗效比较分析,探讨骨水泥强化椎弓根钉在老年退变性腰椎疾患的临床应用价值。方法将40例退变性腰椎疾患需手术的患者随机分成A、B两组,每组20例,A组先行椎弓根钉钉道灌注稍黏稠的聚甲基丙烯酸甲酯骨水泥（每钉道2～3mL）后进行常规椎弓根钉固定加植骨融合术,B组常规椎弓根钉固定加植骨融合术,分别对术中椎弓根钉把持力以及采用JOA临床腰椎手术评分系统、X线片滑脱复位的Boxall标准及椎体间骨性融合的Cook等标准对疗效进行综合评定。结果 40例患者都得到有效随访,随访时间为6～18个月,平均随访8.4个月。A组20例患者中术后全部主观满意,术后采用JOA评分标准评价,总体优良率为90.87%,术后X线片根据Boxall指数标准,复位优良率为100%,植骨融合率100%,植骨融合时间为3～6个月,平均为3.7个月;B组20例患者中有17例术后主观满意,满意率为85%,术后采用JOA评分标准评价,总体优良率为81.56%,术后X线根据Boxall指数标准,复位优良率为80%,植骨融合率为80%,植骨融合时间为3.2～8个月,平均4.8个月,1例术后3个月因椎弓根钉松脱施行骨水泥强化加增粗椎弓根螺钉翻修术,术后主观满意。结论椎弓根钉经骨水泥强化后的近期效果明显优于常规术式,可明显减少术后内植物的失效,提高初次手术的成功率。术中应注意防止骨水泥的外渗漏,减少骨水泥固化过程中发热对周围组织的灼伤;远期效果有待进一步随访比较。     

Load-bearing increases new bone formation in impacted and morselized allografts

The effects of mechanical loading on the incorporation of morselized impacted grafts were addressed in this study. Twelve skeletally mature rabbits were surgically treated. Six rabbits received a proximal tibial joint replacement with a tibial tray and a load-bearing 25-mm long stem. The tibia was packed with fresh frozen, morselized, cancellous rabbit bone. No cement was used. In six other rabbits only the stem was inserted, without a tibial tray, leaving the stem and the likewise impacted bone graft mechanically unloaded. The rabbits were euthanized after 6 weeks, and the tibias were sectioned and analyzed by histomorphometric examination. In the loaded specimens the graft was resorbed and replaced by new bone (30% of area of interest) to a larger extent than in the unloaded specimens. Mechanical loading of an impacted, morselized graft surrounding a conical uncemented stem, increased the amount of new bone that replaced the graft. The ability of morselized impacted grafts to allow mechanical stimulation of ingrown tissue appears to be a principal cause for the success of this grafting procedure.     

Bioactive bone cement as a principal fixture for spinal burst fracture: an in vitro biomechanical and morphologic study

STUDY DESIGN: An in vitro biomechanical and radiographic study to evaluate the properties of a newly developed bioactive bone cement for stabilization of the fractured spine, suitable for minimally invasive application. OBJECTIVES: To determine the mechanical stability of the fractured spine after injection of the newly developed bioactive bone cement under quasi-static and cyclic loading regimens. SUMMARY OF BACKGROUND DATA: Bone cement injection has been reported as a potentially useful, minimally invasive technique for treating vertebral body fracture or stabilizing osteoporosis. However, potential problems associated with the use of polymethylmethacrylate (PMMA) have prompted the search for alternative solutions. The use of bioactive bone cement as a potential replacement for PMMA has been reported. METHODS: Biomechanical and radiographic analyses were used to test the mechanical stability of the fractured spine. The cement used was formed from hydroxyapatite powder containing strontium and bisphenol A diglycidylether dimethacrylate (D-GMA) resin. Twenty-six fresh porcine spine specimens (T10-L1) were divided into three groups: pilot, intact, and cemented. Spinal stiffness and failure strength were recorded in the intact group with the specimens flexed at 10 degrees. Uniform injuries were created in all specimens of the cemented group, and compressive loading was applied with 10 degrees of flexion until a fracture occurred. The bone cement was injected into the fractured spine, and stiffness was evaluated after 1 hour. Failure strength was also recorded after 3000 and 20,000 fatigue load cycles. Morphology of the specimens was observed and evaluated. RESULTS: Results from a cell biocompatibility test indicated that the new bioactive bone cement was favorable for cell growth. Spinal stiffness significantly decreased after fracture (47.5% of intact condition). Instant stiffness of the spine recovered to 107.8% of the intact condition after bone cement injection. After 3000 and 20,000 cycles of fatigue loading, stiffness of the cemented spine was found to be 93.5% and 94.4% of intact stiffness, respectively (P < 0.05). Average failure strength of the spine was 5056 N (after 3000 cycles) and 5301 N (after 20,000 cycles) after bone cement injection and fatigue loading. Radiographs and cross-sectional observations indicated a good cement-bone bonding and fracture fill. CONCLUSIONS: A new bioactive bone cement without cytotoxic effect has been developed. Results show that minimally invasive techniques to apply this cement to porcine spines results in augmentation of mild burst fractures such that the original stiffness and strength of the vertebra are recovered. This new cement therefore shows potential as an augmentation to traditional instrumentation in the surgical management of vertebral fractures. The potential for further clinical applications is currently under investigation.     

Computational assessment of the effect of polyethylene wear rate,mantle thickness,and porosity on the mechanical failure of the acetabular cement mantle

Clinical studies have revealed that aseptic loosening is the dominant cause of failure in total hip arthroplasty, particularly for the acetabular component. For a cemented polyethylene cup, failure is generally accompanied by the formation of fibrous tissue at the cement–bone interface. A variety of reasons for the formation of this tissue have been suggested, including osteolysis and mechanical overload at the cement–bone interface. In this study, a computational cement damage accumulation method was used to investigate the effect of polyethylene cup penetration, cement mantle thickness, and cement porosity on the number of cycles required to achieve mechanical fatigue failure of the cement mantle. Cup penetration was found to increase cement mantle stresses, resulting in a reduction in cement mantle fatigue life of 9% to 11% for a high cup penetration rate. The effect of using a thin (2 mm) over a thick (4 mm) cement mantle also reduced cement mantle fatigue life between 9% and 11%, and greatly raised cancellous bone stresses. Cement porosity was found to have very little effect on cement mantle fatigue life. Failure modes and cement stresses involved suggest that only extreme combinations of a thin cement mantle and high cup penetration may lead to mechanical failure of the cement mantle, thereby allowing wear debris access to the cement–bone interface. A thin cement mantle may also lead to the mechanical overload of the cement–bone interface. In this manner, the authors suggest that the mechanical factors may contribute to the failure mode of cemented polyethylene cups. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:565–570, 2010     

Experimental stabilization of segmental defects in the human femur. A torsional study.

One of each of thirty-five pairs of fresh intact femora were tested to failure in torsion, recording the dynamic torque, the absorbed energy, and the angle of rotation. These results were compared with the results obtained with the contralateral femur, reconstituted after removal of a segment. Intramedullary nails with polymethylmethacrylate cement, strips of titanium mesh with cement, bone plates with and without cement, and multiple Steinmann pins with cement were the reconstituting configurations. Bone plates were the strongest configuration; the failure torques in all cases were limited by the stress concentration effects of the holes in the bone used for screw fixation. The use of cement as an adjunct to single-plate fixation provided some additional strength. The torsional strength of femora fixed with Küntscher and Schneider nails was limited by failure of the cement and bone. The use of titanium mesh with polymethylmethacrylate was less effective, because this composite has a low torsional rigidity. The use of multiple Steinmann pins packed with polymethylmethacrylate in the medullary cavity should be discouraged because severe twisting and fragmentation of the surrounding acrylic will occur at low levels of torque.     

Synchronization of calcium sulphate cement degradation and new bone formation is improved by external mechanical regulation

A major challenge faced in the bone materials of weight‐bearing without internal fixture support is the mismatch of material degradation and new bone formation, leading to weakening or even failure of the overall bony structure. This study demonstrated in the rat femur model that calcium sulphate cement degradation and new bone formation could be better synchronized by external mechanical force. An ascending force in line with calcium sulphate cement degradation could achieve bone healing in 37 days with ultimate load to failure of 87.00 ± 7.30 N, similar to that of intact femur (80.46 ± 2.79 N, p = 0.369). In contrast, the healing process under either a constant force or no force illustrated significant residual defect volumes of 1.47 ± 0.44 and 4.08 ± 0.89 mm³ (p < 0.001), and weaker ultimate loads to failure of 69.56 ± 4.74 and 59.17 ± 7.48 N, respectively (p < 0.001). Our results suggest that the mechanical regulation approach deserves further investigation and may potentially offer a clinical strategy to improve synchronization. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:685–691, 2015.     

Addition of hand-blended generic tobramycin in bone cement: effect on mechanical strength

This study compared the mechanical strength of commercially prepared antibiotic bone cement (Simplex With Tobramycin; Stryker, Mahwah, NJ), cement with generic tobramycin (Pharma-Tek, Huntington, NY) blended in by the orthopedic nursing staff, and standard nonantibiotic bone cement. The results showed an approximate 36% decrease in the strength of the cement with hand-mixed generic tobramycin, while the commercial antibiotic cement remained unchanged relative to the nonantibiotic control. These results indicate the mechanical properties of bone cement can be severely compromised by hand-mixing antibiotics into bone cement at the time of surgery.     

Stromal stem cells and platelet-rich plasma improve bone allograft integration

Early vascular invasion is a key factor in bone allograft incorporation. It may reduce the complications related to slow and incomplete bone integration. Bone-marrow-derived stromal stem cells associated with platelet-rich plasma are potent angiogenic inducers proven to release vascular endothelial growth factor. Our goal was to test whether the combination of stromal stem cells and platelet-rich plasma is able to increase massive allograft integration in a large animal model with sacrifice at 4 months. A critical defect was made in the mid-diaphysis of the metatarsal bone of 10 sheep; the study group received an allograft plus stromal stem cells, platelet-rich plasma, and collagen (six animals) and the control group received only the allograft (four animals). Investigation was done with radiographs, mechanical tests and histomorphometric analysis, including new vascularization. Results showed substantial new bone formation in the allograft of the study group. Bone formation is correlated with better vascular invasion and remodeling of the graft in the study group. These results confirm the key role played by stromal stem cells and platelet-rich plasma in bone repair. Further studies are needed to better define the role stromal stem cells play when implanted alone.     

The interaction of the macrophage and the osteoblast in the pathophysiology of aseptic loosening of joint replacements

Macrophage phagocytosis of cement particles with production of inflammatory mediators is a component of the underlying mechanism of aseptic loosening of joint prostheses. Prostaglandin E₂ (PGE₂), a bone resorbing mediator, has been implicated in the loosening process. Investigations have shown that macrophage phagocytosis of cement particles leads to production of bone-resorbing mediators other than PGE₂. In this study, conditioned medium from macrophages exposed to crushed simplex cement particles stimulated osteoblasts to release radiolabeled arachidonic acid and metabolites. Incubation of osteoblasts in conditioned medium from macrophages exposed to cement particles small enough to be phagocytized increased PGE₂ release 80-fold over unexposed osteoblasts (P<0.001). Incubation of osteoblasts in conditioned medium from macrophages exposed to particles too large to be phagocytized, or to bone cement filtrate, did not stimulate PGE₂ release. We propose that the role of the macrophage in aseptic loosening is primarily to recognize the mechanical failure of the cement mantle by phagocytosis of cement particles and subsequent production of small amounts of specific mediators. These mediators stimulate surrounding osteoblasts to secrete PGE₂, which then amplifies the inflammatory response and ultimately results in bone resorption and aseptic loosening.     

万古霉素复合型抗菌药物骨水泥植入术疗法对骨科术后感染的疗效

目的研究万古霉素复合型抗菌药物骨水泥植入术疗法对导致骨科术后感染的疗效。 方法选取204年2月至2016年2月于本院接受治疗的骨科感染者429例,计算机随机系统将患者随机分为试验组（215例行万古霉素复合抗菌药物骨水泥植入术患者）和对照组（214例行CEMEX GEN抗菌药物骨水泥植入术患者）,依据随访观察指标与治愈标准汇总试验结果,并采用统计学方法进行分析对比。 结果传统的彻底清创外加万古霉素复合型抗菌药物骨水泥植入术疗法对治疗骨科感染较单一型抗菌药物骨水泥植入术（含庆大霉素的抗菌药物）疗效更好,治愈率高达89.77%,而单一型抗菌药物骨水泥植入术（含庆大霉素）的治愈率仅为37.85%,两者差异有统计学意义（χ² = 12.363、P = 0.024）,两种治疗方法的术后并发症发生率差异无统计学意义（χ² = 5.710、P = 0.074）。 结论万古霉素复合型抗菌药物骨水泥植入术疗法对治疗骨科感染疗效远优于单一型抗菌药物骨水泥植入术疗法。     

Mechanical characteristics of the bone-graft-cement interface after impaction allografting.

Impaction allografting is an attractive procedure for the treatment of failed total hip replacements. The graft-cement-host bone interface after impaction allografting has not been characterized, although it is a potential site of subsidence for this type of revision total hip reconstruction. In six human cadaveric femurs, the cancellous bone was removed proximally and local diaphyseal lytic defects were simulated. After the impaction grafting procedure, the specimens were sectioned in 6 mm transverse sections and push-out tests were performed. From the adjacent sections the percentage cement contact of the PMMA cement with the endosteal bone surface was determined. The host bone interface mechanical properties varied significantly along the femur largely due to different interface morphologies. The apparent host bone interface shear strength was highest around the lesser trochanter and lowest around the tip of the stem. A significant positive correlation was found between the percentage cement contact and the apparent host bone interface shear strength (r2 = 0.52). The sections failed in 69% of the cases through a pure host bone interface failure without cement or allograft failure, 19% failed with local cement failure, and 12% with a local allograft failure. The apparent host bone interface strength was on average 89% lower than values reported for primary total hip replacements and were similar to cemented revisions proximally and lower distally. This study showed that cement penetration to the endosteal surface enhanced the host bone-graft interface.