Comparison of Biological and Mechanical Prostheses for Heart Valve Surgery: A Systematic Review of Randomized Controlled Trials / Comparação de Próteses Biológicas e Mecânicas para Cirurgia de Válvula Cardíaca: Revisão Sistemática de Estudos Controlados Randomizados

Abstract Background: The choice of a mechanical (MP) or biological prosthesis (BP) for patients with valvular heart disease undergoing replacement is still not a consensus. Objective: We aimed to determine the clinical outcomes of MP or BP placement in those patients. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) that compared biological prostheses and mechanical prostheses in patients with valvular heart diseases and assessed the outcomes. RCTs were searched in the MEDLINE, EMBASE, LILACS, CENTRAL, SCOPUS and Web of Science (from inception to November 2014) databases. Meta-analyses were performed using inverse variance with random effects models. The GRADE system was used to rate the quality of the evidence. A P-value lower than 0.05 was considered significant. Results: A total of four RCTs were included in the meta-analyses (1,528 patients) with follow up ranging from 2 to 20 years. Three used old generation mechanical and biological prostheses, and one used contemporary prostheses. No significant difference in mortality was found between BP and MP patients (risk ratio (RR = 1.07; 95% CI 0.99-1.15). The risk of bleeding was significantly lower in BP patients than MP patients (RR = 0.64; 95% CI 0.52-0.78); however, reoperations were significantly more frequent in BP patients (RR = 3.60; 95% CI 2.44-5.32). There were no statistically significant differences between BP and MP patients with respect to systemic arterial embolisms and infective endocarditis (RR = 0.93; 95% CI 0.66-1.31, RR = 1.21; CI95% 0.78-1.88, respectively). Results in the trials with modern and old prostheses were similar. Conclusions: The mortality rate and the risk of thromboembolic events and endocarditis were similar between BP and MP patients. The risk of bleeding was approximately one third lower for BP patients than for MP patients, while the risk of reoperations was more than three times higher for BP patients.

Resumo Fundamento: A escolha de próteses mecânicas ou biológicas para pacientes com doença de válvula cardíaca ainda não é um consenso. Objetivo: Determinar os desfechos clínicos de próteses mecânicas e biológicas nesses pacientes. Métodos: Conduzimos uma revisão sistemática e metanálise e estudos controlados randomizados (RCTs) que compararam próteses mecânicas e biológicas em pacientes com doenças de válvulas cardíaca, e avaliamos seus resultados. A busca por RCTs foi feita nas bases de dados MEDLINE, EMBASE, LILACS, CENTRAL, SCOPUS e Web of Science (do início a novembro de 2014). As metanálises foram realizadas usando variação inversa com modelos de efeitos aleatórios. Usamos o sistema GRADE para avaliar a qualidade da evidência. Um valor menor que 0,05 foi considerado significativo. Resultados: Um total de quatro RCTs foi incluído na metanálise (1528 pacientes) com acompanhamento de 2 a 20 anos. Em três estudos, foram utilizadas próteses mecânicas e biológicas mais antigas, e em um estudo próteses contemporâneas. Não foi observada diferença de mortalidade entre os pacientes que receberam próteses mecânicas e biológicas (risco relativo, RR = 1,07; IC95% 0,99-1,15). O risco de sangramento foi significativamente mais baixo nos pacientes que receberam próteses biológicas que naqueles com próteses mecânicas (RR = 0,64; IC95% 0,52-0,78). Contudo, as reoparações foram mais frequentes em pacientes com próteses biológicas (RR = 3,60; IC95% 2,44-5,32). Não houve diferenças estatisticamente significativas entre pacientes com próteses biológicas e mecânicas em relação à embolia arterial sistêmica e endocardite infecciosa (RR = 0,93; IC95% 0,66-1,31; RR = 1,21; IC95% 0,78-1,88, respectivamente). Resultados entre os estudos com próteses modernas e antigas foram similares. Conclusões: A taxa de mortalidade e o risco de eventos tromboembólicos e endocardite foram similares entre os pacientes que receberam próteses biológicas e mecânicas. O risco de sangramentos foi aproximadamente um terço menor nos pacientes com próteses biológicas que mecânicas, ao passo que o risco de reoperação foi mais que três vezes maior nos pacientes com próteses biológicas.

Mid-term effectiveness of large-head metal-on-metal total hip arthroplasty / 中国修复重建外科杂志

Objective: To explore the mid-term effectiveness of large-head metal-on-metal total hip arthroplasty (THA).

Short-term Outcomes of Ceramic Coated Metal-on-Metal Large Head in Total Hip Replacement Arthroplasty / 대한고관절학회지

PURPOSE: This study characterizes the short-term outcomes of ceramic coated metal-on-metal (MoM) large head total hip arthroplasty (THA) in prospectively selected patients aged 70 to 75 years. MATERIALS AND METHODS: Eighteen patients (18 hips) between the ages of 70 and 75-years old with THA using ceramic-coated MoM large heads between June 2014 and December 2014 were evaluated. We prospectively selected patients younger than 70 years for bipolar hemiarthroplasty and older than 75 years for conventional THA. There were one case of osteoarthritis, 8 cases of femur neck fracture, and 9 cases of intertrochanteric fracture. All patients underwent clinical and radiological follow-up at 6 weeks, 6 and 12 months, and every year postoperatively. The mean duration of follow-up was 24.2 months (range, 18–34 months). RESULTS: The average Harris hip score at the final follow-up was 81.0, except one case which was ultimately converted to conventional THA due to acetabular cup loosening. Radiographically, mean acetabular cup inclination was 45.8°(range, 38–56°) and anteversion was 20.1° (range, 11–25°). The average femoral head size was 48.7 mm. All stems were neutral-positioned except 1 varus-positioned stem. There was 1 case of a soft tissue infection, 3 patients complained of persistent groin pain, and no dislocations occurred. CONCLUSION: Ceramic coated large MOM articulation (ACCIS) have many complications: cup loosening, groin pain, which can lead to fatal outcomes in the elderly patients. Especially in patients with communicated intertrochanter fracture (AO 31-A22, 23), careful attention should be paid to the choice of surgical option.

Prótesis de superficie de cadera en presencia de osteosíntesis femoral proximal / Hip resurfacing in the presence of proximal femoral osteotomy

Describimos un caso de reemplazo de superficie de cadera en un paciente con artrosis posterior a necrosis ósea avascular y material de osteosíntesis femoral proximal de difícil extracción. Con las prótesis de superficie se logran buenos resultados si la indicación y la técnica quirúrgica son las correctas. En este caso, facilitó mucho la artroplastia, con un muy buen resultado funcional; se evita una cirugía con mayor morbilidad y una tasa más alta de complicaciones y revisiones, como ocurre con los reemplazos de cadera convencionales tras el retiro de la osteosíntesis proximal de fémur. Los cirujanos de cadera atendemos a estos pacientes con frecuencia; estamos seguros de que este tipo de cirugías debe incluirse en nuestro arsenal terapéutico. A pesar de las desventajas de esta artroplastia (fricción metal/metal, curva de aprendizaje, fracturas del cuello femoral), consideramos que, en estos casos, dichas complicaciones están compensadas por la simplicidad del procedimiento.

We describe a hip resurfacing case in a patient with arthrosis after avascular necrosis and proximal femoral osteosynthesis material difficult to remove. Hip resurfacing achieves good results when its indication and technique are correct. In this case, it facilitated the arthroplasty achieving an excellent functional result; avoiding a major surgery and the high rate of complications and revisions, as it occurs with conventional hip replacements after osteosynthesis of the proximal femur. Surgeons frequently face this type of patients; therefore we are convinced that this procedure must be in our therapeutic arsenal. Besides the disadvantages of this arthroplasty (metal on metal friction, learning curve, neck fracture) we consider that they are compensated for by the simplicity of the procedure.

Metal-on-metal Articulation of Total Hip Replacement / 대한고관절학회지

Metal-on-metal (MoM) total hip replacement (THR) and hip resurfacing have an advantage of low wear rate and greater stability by larger head size and different characteristics of wear mechanism, tribology, lubrication or generating wear debris compared to conventional metal-on-polyethylene THR. Although the mid- or long term clinical reports of second generation MoM THR were excellent, concerns about local and systemic effect by metal particles or metal ions were remained. Recently, reports have emerged of abnormal soft-tissue reactions to metal particles or metal ions and some hip resurfacing implants were expelled from the market due to high revision rate. This article includes the history of MoM THR, tribology, the biologic effect of metal particles and ions, the clinical results of MoM THR and the issues regarding the problems associated with hip resurfacing.

Dynamic edge contact behavior of metal-on-metal hip joint replacements / 医用生物力学

Objective To investigate the edge contact behavior of conformal spherical hip joint replacements under the given dynamic contact displacement condition. Methods Based on the developed spherical-grid-data model, the contact behavior and corresponding edge contact behavior of a typical metal-on-metal hip joint replacement was simulated under the increasing displacement between the acetabular cup and femoral head. Results It was found from the obtained results that the vertical and horizontal component of the support force due to contact pressure increased with the dynamic contact displacement increasing. The vertical component of support force for the edge contact showed a slower variation tendency than that for the non edge contact, while the corresponding horizontal component of support force increased more significantly with the dynamic displacement. In addition, the corresponding contact pressure distributions and the contact areas of hip joint replacements for edge contact and non-edge contact were different. Conclusions The significant edge contact behavior of hip joint replacements with bigger cup inclination angle occurrs with the increasing displacement of femoral head to the acetabular cup, which will cause the sliding between contact surfaces and additional wear since the horizontal support force increases. This provides a reference for the wear assessment and manufacturing of hip joint replacements.

Wear prediction for metal-on-metal hip joint replacements / 医用生物力学

Objective To develop a wear prediction model for hard-on-hard hip joint replacement under the condition of complex dynamic loading and time-dependent motion, and to apply it to the study on wear prediction of the typical metal-on-metal hip joint replacement in the complicated three-dimensional (3D) physiological motion condition. Methods The finite element model for contact mechanics was established and the fixed-tracked method was adopted to make the dynamic wear reappear on the bearing surface of artificial hip joint with 3D Euler transformation, and the data communication about the corresponding contact and wear for simulation was also made. Results The wear prediction test showed that the spherical bearing geometry of the artificial hip joint gradually became the non-spherical form due to the wear with time; meanwhile, the corresponding contact area was increased, the distribution of the contact pressure tended to be flattened, and the maximum contact pressure was decreased. Conclusions The wear prediction model developed here for metal-on-metal hip joint replacements with bilateral bearing surfaces under the condition of complex dynamic loading and motion could be used to carry out simulation test for the wear prediction of metal-on-metal artificial joint, which provides a new method to understand the wear mechanism of hip joint replacement.

Effect of edge contact on metal-on-metal hip joint replacements / 医用生物力学

Objective To study the contact mechanics of metal-on-metal hip joint replacements under different walking conditions, particularly for the edge contact behavior between the cup and the head of the bearing due to large range movement. Methods The finite element model of a typical hip joint replacement with conformal spherical bearing was established to simulate the edge contact of hip joint replacement under the given cup inclination angles and vertical loads. Results The maximum contact pressure decreased slightly and the contact area increased when the cup inclination angles increased within the range of 0°~60°. When the cup inclination angles were more than 80°, the corresponding contact area moved to the cup edge, the maximum contact pressure and distribution range increased, but the position of the maximum contact pressure moved from the initial contact point to the new point with 6°~9° in the direction of the increasing cup inclination angle to balance the corresponding contact pressure distribution and the loaded human weight. Conclusions Different edge contact behavior of hip joint replacements tends to occur due to the bigger cup inclination angle. Therefore, much attention should be paid to the problem of edge contact for both the clinical surgery and the manufacturing of hip joint replacements.

Falha precoce das artroplastias totais de quadril metal-metal cimentadas / Early failure of metal on metal cemented total hip arthroplasty

Avaliamos radiograficamente e clinicamente 56 pacientes submetidos à artroplastia total de quadril com superfície metal-metal cimentada com seguimento médio de 7,7 anos. Apenas uma revisão por soltura asséptica foi realizada, porém 20,8% dos pacientes apresentaram sinais de progressão da linha de radiolucência acetabular.

Artroplastía total de cadera primaria metal-metal con megacabezas en mayores de 75 años / Metal on metal primary total hip arthroplasty with heads greater than or equal to 38 millimeters in patients over 75 years

Objectives: Determine if patients over 75 years old that were operated by primary total hip arthroplasty, the use of heads greater than or equal to 38 mm may reduce the risk of dislocation without an increase in loosening. Knowing that press-fit was the only mean of fixing the acetabular component. Materials and Methods: A retrospective observational cohort study was conducted between 2005 and 2008. We included 25 patients over 75 years old that operated with metal on metal primary total hip arthroplasty, monoblock acetabular cup press-fit without screws and heads greater than or equal to 38 mm diameter. We conducted clinical and radiological controls at 1,3,6, 12 months and then annually, recording episodes of dislocation, signs of acetabular component loosening (migration of 2 mm, angulation more than 5 degrees and radiolucid line in the 3 Charnley-DeLee zones) and the Functional Merle Scale. Results: The mean follow up of patients was 2 years (1-4 years). The average Merle Score was 16.7 (9-18), catalogued as Very Good 17 (68 percent), Well 4 (16 percent), Fair 2 (8 percent) and Bad (4 percent) patient. Two patients had complications, nondisplaced calcar periprosthetic intraoperative fracture ans sciatic nerve injury. There were no reoperations and no cases of prosthetic dislocation or loosening. Conclusions: In thi population, the use of acetabular component fixed by only press-fit without screws associated with heads greater than or equal to 38 mm, increases stability and is a safe procedure, and so far we have not seen any loosening events.

Objetivo: Determinar si en la artroplastía total de cadera (ATC) primaria en pacientes mayores de 75 años, es posible disminuir el riesgo de luxación con el uso de cabezas mayores o iguales a 38 mm, sin un aumento del aflojamiento al utilizar la fijación mecánica como único medio de fijación del componente acetrabular. Materiales y Métodos: Estudio observacional, prospectivo, del tipo cohorte, realizado entre los años 2005 y 2008. Se incluyeron 25 pacientes mayores de 75 años, sometidos a una ATC con par de fricción metal-metal, cotilo monoblock con fijación mecánica sin tornillos y megacabezas, definidas como diámetros > 38 mm. Se realizaron controles clínico radiológicos a los 1,3,6, 12 meses y luego anualmente, registrándose episodios de luxación, signos de aflojamiento del componente acetabular (migración de 2mm, angulación mayor a 5º y línea radiolúcida en las 3 zonas de Charnley-DeLee) y la Escala Funcional de Merle: Resultados: El seguimiento promedio de los pacientes fue de 2 años (1-4 años). El promedio del Score de Merle fue 16,7 (9-18), catalogándose como Muy Bueno a 17 (68 por ciento), Bueno a 4 (16 por ciento), regular a 2 (8 por ciento) y Malo a 1 (4 por ciento) paciente. Dos pacientes presentaron complicacines, y una fractura periprotésica intraoperatoria del calcar no desplazada y una lesión del nervio ciático. Ningún paciente fue reoperado. No se observaron casos de luxación protésica ni de aflojamiento. Conclusiones: En la población estudiada, el uso de componentes acetabulares fijados únicamente mediante fijación mecánica sin tornillos asociado a megacabezas, aumenta la estabilidad protésica y es un procedimiento seguro, ya que hasta la fecha no hemos presentado eventos de aflojamiento.

Metal-on-Metal Bearing in Total Hip Arthroplasty

Metal-on-metal bearings have been reintroduced with the improved materials, design and manufacturing quality control as an alternative to the conventional metal-on-polyethylene articulation. The advantages of total hip arthroplasty using a metal-on-metal bearing include an extremely low wear rate, a very small risk of in vivo fracture and the use of a larger femoral head. These advantages have led to an increased use of metal-on-metal bearings for younger and more active patients with advanced hip disease. Concerns remain regarding the elevated levels of metal ions and their potential consequences such as metal hypersensitivity or potential carcinogenesis.

Minimum 3 years Follow-up Results of Metal on Metal Hip Resurfacing Arthroplasty

PURPOSE: To present the survival of consecutive patients with a minimum of three years follow-up after undergoing a metal-on-metal hip resurfacing arthroplasty. MATERIALS AND METHODS: Twenty hips from twenty patients (male: 16, female: 4) who underwent metal-on-metal resurfacing arthroplasty between October 2001 and April 2004 were followed up for at least 3 years. The mean patient age was 49 years (range 23~70), and the mean follow-up period was 56 months (range 36~84 months). A clinical evaluation was performed using the Harris hip score, and radiologic evaluation was performed regularly after surgery with plain radiographs. RESULTS: The mean Harris hip score improved from 46 points (range 73~32) preoperatively to 94 points at final follow-up. There were no cases of radiolucency or osteolysis around the stem or acetabular cup, and there was no migration of the acetabular or femoral component. The average femoral stem-shaft angle was 135degrees(range 121degrees- 139degrees), and at the final follow-up study, there was no change of the femoral stem. CONCLUSION: In the short-term, metal-on-metal resurfacing arthroplasty performed on the basis of bone quality and patient selection, showed excellent clinical and radiological results. Hip resurfacing is an attractive option for young patients fearing a potentially difficult future revision or for more active patients with hip disease.

Total Hip Arthroplasty with Use of Metal-on-Metal Articulation

Purpose: This paper reports the clinical and radiologic consequences in a group of patients who underwent metal on metal total hip arthroplasty based on a follow-up of at least five years. Materials and Methods: Forty-three cases (41 patients) were enrolled in this study. The patients underwent surgery from June 1995 to March 2002. The mean follow-up period was 93 month. The evaluation focused on the VAS-pain score, WOMAC score and Harris Hip score. Follow-up radiographs were taken at 6 weeks, 3 months, 6 months, and 12 months after surgery. Results: At the last follow-up, the VAS-pain score, WOMAC score and Harris Hip score improved from 8.1 to 3.1, 76.4 to 13.3, and 42.7 to 90.8, respectively. The X-rays showed no signs of detectable wear. However, some complications were encountered; 3 infections, 1 periprosthetic femoral fracture, 1 pelvic osteolysis and 1 dislocation. Conclusion: The results appear quite satisfactory considering the wear resistance, pain and function after surgery irrespective of age. However, a long-term follow-up will be needed to obtain reliable information on the influence of metal particles on the human body.

The Retrieval Study of the Rough Blasted Surface Finish Cement Stem in Metal on Metal Total Hip Arthroplasty

PURPOSE: This study investigated the possible etiologic role of stem loosening and osteolysis by examining the surface of a rough blast retrieval cement stem and physical activity in second generation metal-on-metal (MOM) total hip arthroplasty (THA) MATERIALS AND METHODS: Forty one patients (43 hips) were analyzed retrospectively from Jan. 1996 to Dec.1998. Of the femoral stem, a rough blasted (Ra=1.6 um) cement stem and a cementless Ti-alloy stem was used in 18 and 25 hips, respectively. The mean follow-up duration was 10.15 years. Each patient was evaluated clinically by the HSS and radiographically by Engh's method. Scanning electron microscopy was used to observe the retrieved femoral stem and histology studies were performed. RESULTS: The mean Harris hip score improved from 56.2 points before surgery to 92.6 points after surgery. All the cementless stems and cups showed excellent results at the last follow-up. Eight of the rough blast cement stems were revised. Seven showed loosening and one was a recurrent dislocation. Cross-validation evaluation revealed osteolysis to be associated with a rough surface cement stem of metal on metal THAs (p=0.001). In addition, patients who underwent strenuous activity had a higher incidence of osteolysis (p=0.031). CONCLUSION: These findings suggest that a rough blast surface cement stem is associated with early osteolysis and loosening in patients with a metal-on-metal hip replacement. A prospective study with a large group of patients and multiple diagnostic methods will be needed to determine if there is a causal relationship between metal hypersensitivity and osteolysis. These results suggest that a cement stem with a rough blasted surface should be considered in metal-on-metal total hip arthroplasty.

Outcomes of cementless Metasul metal-on-metal total hip arthroplasty / 中国矫形外科杂志

[Objective]To investigate the outcomes of cementless metasul metal-on-metal total hip arthroplasty.[Method]Metasul metal-on-metal total hip arthroplasty of 30 hips in 25 patients was performed from August 2003 to December 2005.There were 11 males and 14 females with an average age of 47 years(28-72 years).Harris hip scores were determined before surgery and at the last follow-up examination.Standardized radiographs were obtained to evaluate component conditions.Blood samples were taken to determine serum chromium levels with use of atomic absorption spectrometry.[Result]Twenty-three patients(28 hips)were followed up with a mean period of 3.6 years(2.5-4.8 years).The mean Harris hip score improved from 49.5(17-78)points preoperatively to 93.4(55-99)points at the time of final follow-up.Twenty-two hips(85%)had an excellent result.Radiolucent lines were found in 3 hips.Focal femoral osteolysis was seen only in one patient.Sciatic nerve was injured in one case,which showed rehabilitation after 2.5 years.One hip had periprothetic infection because of diabetes 4 years after operation.There was no measurable wear by X-rays.No dislocation or fracture was found.The median serum chromium concentration was 0.082 ?g/mL(0.020～0.140 ?g/mL).No patient was diagnosed with renal insufficiency or hematologic malignancy during the study period.[Conclusion]The outcomes of Metasul metal-on-metal total hip arthroplasty are satisfactory.However,additional follow-up is necessary to determine any possible long-term deleterious effects.

Cementless Total Hip Arthroplasty using Metal on Metal Articulation / 대한정형외과학회잡지

PURPOSE: To evaluate the early midterm clinical and radiographic results of cementless total hip arthroplasty using Metasul metal-on-metal articulation. MATERIALS AND METHODS: Seventy-four (63 patients) of ninety three consecutive total hip arthroplasties (81 patients) using a metal on metal bearing surface and implanted from November, 1994 to April, 1998 with a minimum 3 year follow-up were analysed clinically and radiographically. The mean age at the time of index operation was 43.1 years (range; 17-65 years) and the mean follow up period was 61.2 months (range; 36-90 months). Clinical evaluation was performed by awarding Harris Hip scores (HHS). Radiographic evaluation was performed in terms of the stability of components, osteolysis, and wear rate. RESULTS: The average Harris hip score was 49.4 preoperatively and 91.4 at the most recent follow-up evaluation. Excellent or good results were found in 67 hips (90.5%). Two femoral components were loose radiographically, and one of the loose components was revised due to subsidence. Two acetabular components were revised (1 loosening and 1 continuous radiolucent line). One diffuse pelvic osteolysis was found around a stable component. Wear could not be measured radiographically. CONCLUSION: Compared to other bearing surface, total hip arthroplasty using a metal-on-metal bearing surface demonstrated very low wear rates and osteolysis at an average 5 year follow up results, however, a longer follow up is needed to evaluate wearinduced osteolysis.

Preliminary Results of Uncemented Metal on Metal Total Hip Replacement Arthroplasty / 대한정형외과학회잡지

Particulate wear debris(polyethylene, polymethylmethacrylate and metal particles, or combination of these) can initiate aseptic loosening. To eliminate polyethylene debris and reduce the total amount of wear, metal on metal bearings(Metasul) which were made of a wrought Co-28Cr-6Mo-0.2C alloy, were introduced. From May 1994 total hip replacements using a Metasul metal on metal articulation were performed by the authors. 34 patients with 40 hips with minimum follow-ups during 24 months were analysed in this study. The mean follow up period was 31 months(ranging from 24 to 47 months). We used Armor cups and standard cups as acetabular comporients and SL stems, CLS stems and cone stems as femoral components. Preoperative average Harris hip score of 48 points became postoperatively 93(from minimum 81 to maximum 100). And there were slight and occasional thigh pains in 2 cases(5%). There were no revisions for the early aseptic loosening of femoral stems or stem failures. Radiologic evaluation which revealed mild calcar atrophy was developed in 33 cases(82.5%), revealing cortical hypertrophy in 10 cases(25%). Osteolysis was not noted around the prosthetic stem nor around the cup. Radiolucent lines were found in 9 cases of femoral components(22.5%) and in 1 case of acetabular component(2.5%) and subsidence of more than 3mm in 1 case of femoral components(2.5%) were also found. There was 1 case of definitive loosening of acetabular component(2.5%). These also showed that endosteal bone formation adjacent to femoral prosthesis was developed in 22 cases(55%) but no distal pedestal and stem shift occurred. The short-term but satisfactory results of the contemporary metal on metal articulation investigated in this study were encouraging and warrant continued study.