In vitro cyclic testing of the Exeter stem after cement within cement revision

Cement-within-cement (C-C) revision arthroplasty minimizes the complications associated with removal of secure polymethylmethacrylate. Failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the cyclic fatigue properties of bilaminar cement mantles after C-C revision in vitro with the Exeter stem. Seven Exeter stems were cemented into Sawbone femurs and removed, and new undersized stems were cemented into the preserved mantle. The new constructs were loaded for 1,000,000 cycles at body temperature. Cement mantles were inspected postcycling. In no case was there delamination or failure of the cement mantle. The findings support the hypothesis that use of a thin revision cement mantle in conjunction with a polished double-tapered stem is not detrimental to the overall success of the implant. In the presence of a secure cement-bone interface in suitable patients, we recommend C-C revision techniques using double-tapered polished femoral stems.     

Effects of Vancomycin,Cefazolin and Test Conditions on the Wear Behavior of Bone Cement

Antibiotic cement has been recommended in the treatment of prosthetic infections. The purpose of this study was to investigate the mechanical behavioral changes in cement loaded with two antibiotics, vancomycin and cefazolin, in dry and liquid medium. Six groups and four study conditions were established according to the doses of antibiotic used and the ageing (immersion in phosphate buffered saline) of the samples. Properties evaluated were friction coefficient and wear. Samples in dry medium showed higher wears than in liquid. Antibiotic selection did not influence wear properties tested in dry conditions, however, in liquid medium, there were higher frictional coefficients and wear for cefazolin loaded cement after one week and for vancomycin and cefazolin after one month. The results suggest that antibiotic cements behave differently in liquid and that the molecular characteristics of antibiotics are essential for determining this influence.     

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.     

Porosity of neat and composite bone cement mantles

The effect of fiber additions to bone cement on femoral cement mantle porosity was determined. Eighteen porcine femurs were implanted with a cemented prosthesis. Three cement types were used: as-received cement, cement with untreated polyethylene terephthalate fibers, and cement with treated polyethylene terephthalate fibers. Radiographs revealed all cement mantles as grade B, with slight radiolucency at the cement-bone interface. The cement mantles were sectioned at 7 levels, and porosity was measured at each level. All specimens had similar porosities, with an overall mean percentage of porosity of 3.3%+/-2.2% and a mean pore count of 208+/-160 per section. The high pore count and porosity were not visible on the standard clinical radiographs.     

Shear properties of bilaminar polymethylmethacrylate cement mantles in revision hip joint arthroplasty

Although cement-within-cement revision arthroplasty minimizes the complications associated with removal of secure PMMA, failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the variability in shear properties of bilaminar cement mantles related to duration of postcure and the use of antibiotic cements. Bilaminar cement mantles were 15% to 20% weaker than uniform mantles (P < .001) and demonstrated variability in shear strength related to duration of postcure of the freshly applied cement (P < .001). The use of Antibiotic Simplex did not significantly influence interfacial cement adhesion (P = .52). Interfacial adhesion by mechanisms other than mechanical interlock plays a significant role in the bond formed between new and old PMMA cements, with an important contribution by diffusion-based molecular interdigitation. In the presence of a secure cement-bone interface, we recommend cement-within-cement revision techniques in suitable patients.     

Radiological evaluation of the femoral component fixed with interface bioactive bone cement in revision total hip arthroplasty

Thirty cases whose femoral side was operated with interface bioactive bone cement technique in revision total hip arthroplasty for aseptic loosening and followed for more than 6 years were evaluated. The present study includes 2 men and 28 women with an average age at operation of 60 years. Mean postoperative follow-up period was 9 years. Rerevision of femoral component was not found. Possible loosening was observed in 1 case, using the criteria of Harris. Among 21 cases whose cementing grade was assessed as B or C in postoperative x-ray, radiolucent line at bone-cement interface has disappeared before last follow-up in 11 cases. The present study revealed that the good result was obtained using the interface bioactive bone cement technique for reconstruction of aseptic femoral loosening.     

Revision arthroplasty facilitated by ultrasonic tool cement removal: An evaluation of whole bone strength in a canine model

Ultrasonic driven tools have been developed to facilitate the removal of bone cement during revision arthroplasty. The effect on whole bone strength of cement removal by ultrasonic tools was examined in a canine femur model. Paired, fresh-frozen canine femora were divided into two groups. In group A, one femur from each pair was subjected to cement extraction with ultrasonic tools. In group B, one femur from each pair was subjected to manual cement extraction. Contralateral femora from each pair served as controls to determine the strength of intact femora. Torsional fractures were produced using a servocontrolled hydraulic testing machine (Minneapolis Testing System, Minneapolis, MN). Maximum torque, maximum angle, and energy capacity to failure were determined. Results were recorded as a reduction in percent value of the tested specimen versus the contralateral control. When comparing femora with cement removal by ultrasonic tools to the contralateral control femur, there were no statistical differences in ultimate torque (P = .83), maximum angle (P = .89), and energy capacity (P = .74) by analysis of variance. In addition, there were no significant differences between the group with ultrasonic tool cement removal and the group with manual tool removal. The authors conclude that in this canine model, removal of cement with ultrasonically driven tools has no adverse effects on whole bone strength.     

Antibiotic-loaded bone cement vs. plain cement as an infection prophylaxis in primary elective shoulder arthroplasty

HypothesisThe use of antibiotic-loaded bone cement (ABC) in the setting of revision arthroplasty for deep infections is a broadly accepted practice. However, its use in the setting of primary arthroplasty continues to be controversial with few studies assessing the efficacy of ABC for primary total shoulder arthroplasty (TSA). The purpose of this study was to determine whether the use of ABC in primary TSA is associated with a difference in the risk of deep infections.MethodsA retrospective cohort study was conducted using data from a United States integrated health-care system’s shoulder arthroplasty registry. Patients aged ≥18 years who underwent primary elective anatomic TSA for osteoarthritis or reverse TSA (RTSA) for rotator cuff arthropathy with implanted cement information were included in the study (2009-2020). We compared patients that received ABC to those who received plain cement and are at risk of revision due to deep infection within 5 years of follow-up using Cox proportional hazard regression weighted with the inverse propensity score, stratified by procedure type.ResultsThe study sample included 6409 TSAs for osteoarthritis and 779 RTSAs for rotator cuff arthropathy performed by 198 surgeons at 58 hospitals. In the TSA group, 20% received ABC; the cumulative infection probability at 5 years of follow-up was 0.5% and 0.6% for the ABC and plain cement groups, respectively. After covariate adjustment, no significant difference in infection risk was found (hazard ratio = 0.72, 95% confidence interval = 0.43-1.21, P = .216). In the RTSA group, 19% received ABC; the cumulative infection probability at 5 years of follow-up was 2.7% and 0.9% for the ABC and plain cement groups, respectively. After covariate adjustment, no significant difference in infection risk was found between the 2 cement groups (hazard ratio = 1.47, 95% confidence interval = 0.66-3.26, P = .341).ConclusionIn this study of more than 7000 primary elective shoulder arthroplasties performed in patients with a standard risk of infection, antibiotic bone cement did not confer any risk-reduction for periprosthetic infection when compared to plain bone cement. Different at-risk pathogen profiles may develop with prolonged use of antibiotic bone cement.     

抗生素骨水泥和连续灌注治疗关节置换后感染

目的　为人工关节置换术后感染探索新的治疗方法。方法　回顾 68例人工关节置换手术 ,发生术后感染 10例 ,其中全膝关节置换术后感染 4例 ,全髋关节置换术后感染 6例 ,全部采用抗生素骨水泥同时采用抗生素连续灌注。结果　病程在 2周内的 4例用此方法全部保留假体成功 ,其余 6例病程都在 4周以上 ,保留假体失败。结论　关节置换术后感染是严重并发症 ,本方法是一种保留假体的补救措施。     

Femoral nerve compression after migration of bone cement to the groin after hip arthroplasty

Although often a benign complication of total hip arthroplasty, cement extrusion can cause nerve, vessel, and organ compression. We report the case of a 70-year-old male patient in whom an extruded cement mass migrated anteriorly and compressed the femoral nerve and impinged on the femoral artery producing acute, severe groin pain with neuralgia 9 years postoperatively. Paresthesia of the anterior and medial thigh was found on examination. Radiographic, ultrasound, and computed tomographic studies confirmed a 6 × 1.5-cm mass of bone cement in the right groin compressing the femoral nerve that was removed successfully at surgery. Six months postoperatively, the patient's pain had resolved, but hyperesthesia of the medial thigh remained.     

Improving initial acetabular component stability in revision total hip arthroplasty calcium phosphate cement vs reverse reamed cancellous allograft

A reproducible retroacetabular defect was created bilaterally in 9 cadaver pelves. The defects were filled with either an injectable, bioresorbable, calcium phosphate cement, or reverse-reamed cancellous allograft. An uncemented acetabular shell was impacted, followed by the placement of an appropriate liner. The pelves were then sectioned, and each half was loaded in a material testing machine to simulate walking on the construct over a several week period. The cement-filled defects lasted a greater number of cycles before failure and had greater cup stability and stiffness. The use of resorbable bone void filler for retroacetabular defects shows promise in this biomechanical analysis. Long-term clinical follow-up is warranted to track osseointegration of the implant and restoration of bone stock between this and other clinically accepted surgical techniques.     

Clinical results of isolated tibial component revisions with femoral component retention

The purpose of this study is to report the outcome for a consecutive series of isolated nonmodular tibial component revisions. A consecutive series of 6548 total knee arthroplasties (6024 metal backed; 524 all-polyethylene) were performed with nonmodular tibial components of which 54 knees (0.82%) (22 metal backed; 32 all-polyethylene) underwent isolated tibial component revision with femoral component retention. Clinical outcome and component survivorship were examined. Pain scores improved from 19 to 42 points and Knee Society score improved from 62 to 87 points after revision. At a mean of 6.6-year follow-up, the survivorship of the revised tibial components and retained femoral components, with aseptic loosening as the end point, was 100%.     

Precooling of the femoral canal enhances shear strength at the cement-prosthesis interface and reduces the polymerization temperature.

Preheating of the femoral stem in total hip arthroplasty improves the cement-prosthesis bond by decreasing the interfacial porosity. The main concern, however, is the potential thermal osteonecrosis because of an increased polymerization temperature. In this study, the effects of femoral canal precooling on the characteristics of the cement-stem interface were evaluated in an experimental model for three test conditions: precooling of the femoral canal, preheating of the stem (44 degrees C), and a control in which stems were inserted at room temperature without thermal manipulation of the implant, cement, or bone. Compared to the control group, precooling of the femoral canal and preheating of the stem had similar effects on the cement-stem interface, with greater interfacial shear strength and a reduced porosity. Femoral canal precooling also produced a lower temperature at the cement-bone interface. No difference was found in the ultimate compressive strength of bone cement for the three preparation conditions. Based on this laboratory model, precooling of the femoral canal could improve shear strength and porosity at the stem-cement interface, minimize thermal injury, and maintain the mechanical strength of the cement.     

Towards the optimization of the preparation procedures of PMMA bone cement

The mechanical properties and thermal history of polymethyl‐methacrylate bone cement vary significantly with the preparation procedure used. Because the polymerization reaction is exothermic, many researchers have attempted to minimize thermal osteonecrosis due to heat generation by altering procedures in the preparation of the cement. In most previous studies, only one or two aspects of the preparation procedure were controlled, and there has been little research that comprehensively examines the effects of preparation on the cure kinetics and resulting properties of bone cement. In this study, cement viscosity, cement layer thickness, initial cement temperature, initial metal component temperature, and mixing method were varied to assess the effects on the cement. Maximum temperature, polymerization time, necrosis index, bending strength, and porosity were chosen to evaluate the different preparation procedures, where an optimal procedure would minimize necrosis, reduce cement cure time, and maximize bending strength. Design of Experiments (DOE) was used to examine the main effects and interactions of preparation techniques. Among the most prominent results, it was found that the cure kinetics and the related quantities are primarily controlled by the initial metal component temperature and that the bending strength is most dependent on the mixing method. For the two formulations studied, the optimum preparation procedures should keep cement and metal components at room temperature prior to mixing with a vacuum mixing system. Reducing cement mantle thickness may also be advantageous, as it reduces the maximum temperature and the risk of tissue damage. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:915–923, 2016.     

The effect of cement gun and cement syringe use on the tibial cement mantle in total knee arthroplasty

Evidence suggests that a thicker cement mantle improves fixation strength and resistance to tensile and shear forces in the tibial component of total knee arthroplasty. A low proportion of orthopaedic surgeons currently use techniques to improve cement penetration in the tibial plateau. We demonstrate that the use of a pressurized cement gun or cement syringe provides a highly statistically significant difference (P < .001) to the depth of the tibial cement mantle and reduction in radiolucent lines when compared to cement applied by hand. This ensures a thicker cement mantle and may reduce the possibility of early failure by improving the strength of fixation and the resistance to tensile and shear forces. There is no statistical difference in the cement mantle produced by the cement syringe and the cement gun.     

Nonunion of extended trochanteric osteotomies in impaction grafting femoral revisions

Extended trochanteric osteotomies have been recommended to facilitate femoral component removal, femoral cement removal, and acetabular exposure in cases of difficult revision hip arthroplasty. Complications due to the osteotomy have been rare and no nonunions have been reported when this osteotomy has been used in conjunction with extensively porous-coated implants. It has been suggested that the osteotomy should also work well with impaction grafting revisions. This is a report of two cases of nonunion of extended trochanteric osteotomies in which the impaction grafting technique was used.     

Effect of cement pressure and bone strength on polymethylmethacrylate fixation

The effect of the quality of the bone and of the cement pressurization magnitude and duration on the fixation achieved with polymethylmethacrylate (PMMA) bone cement is studied in vitro. Seventy-one cementbone interface specimens, prepared under various conditions of pressurization of low-viscosity bone cement, are tested in tension. The load at failure and the maximum cement penetration are measured to assess the fixation achieved, and the quality of the bone is assessed by determining the compressive strength of each of the bone specimens. Statistical analysis of the data indicates that the pressure magnitude is the most influential of the factors considered in the cement penetration behavior and in the development of failure load capacity. The duration of the pressure does not appear to be a significant factor. The cement penetration is a decreasing function of the bone strength, reflecting a decrease in the porosity and an increase in the area fraction. Although not directly measured in these tests, these latter bone properties are indirectly measured by the bone compressive strength. The effect of increasing bone strength on the failure load is nonlinear. The development of adequate failure load capacity is the result of a balance between the cement penetration allowed by the porosity of the bone and the inherent strength of the cancellous bone itself. Weak bone, although adequately penetrated by cement, cannot provide strong fixation. Stronger, denser bone limits cement penetration, but pressurization enhances development of failure load capacity through more complete infusion and interlocking of the cement in the available pore space. The strength of the fixation achievable for any bone is limited by the intrinsic strength of the bone. An optimal depth of cement penetration of 4 mm and an optimal bone area fraction of 0.20 are suggested for the most effective fixation.