Alumina Femoral Heads Research Articles

Polyethylene Wear Against Alumina and Zirconia Heads in K-Max Total Hip Arthroplasty

Polyethylene wears of 22.225 mm diameter alumina and zirconia femoral heads in cemented total hip arthroplasty (THA) were compared at mean follow-up of five years. Ninety-six primary cemented K-MAX THA in eighty-seven patients were observed, forty-six hips with alumina heads and fifty-one hips with zirconia heads. Both of the mean linear wear rate and the mean volumetric wear rate of the polyethylene against zirconia were significantly higher that those of alumina (p<0.01, p<0.01, respectively). The monoclinic phase content and roughness rose up on the surfaces of two retrieved zirconia heads from revision surgeries. This was supposed as the differences of thermal conductivity between alumina and zirconia, for which local temperature was higher in zirconia head, leading to the phase transformation and lower-temperature aging degeneration (LTAD) of zirconia head surface.

Alumina-on-Alumina Total Hip Arthroplasty

Ceramic-on-ceramic couplings are attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. Disappointing experiences with alumina ceramic bearings in the past have led to many improvements in the manufacture and design of ceramic implants. The purpose of the present study was to report the results of contemporary alumina-on-alumina total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum duration of follow-up of five years. We evaluated the results of a consecutive series of 100 primary alumina-on-alumina total hip arthroplasties that had been performed with use of a metal-backed socket and a cementless stem in eighty-four patients. All of the patients were sixty-five years of age or younger (mean age, forty-one years), and a single surgeon performed all of the procedures. After a minimum duration of follow-up of sixty months, one patient (one hip) had died and four patients (six hips) had been lost to follow-up, leaving a total of seventy-nine patients (ninety-three hips) available for study. All of these patients were evaluated clinically and radiographically with special attention to wear, periprosthetic osteolysis, and ceramic failure. The mean Harris hip score was 97 points at the time of the latest follow-up evaluation. All prostheses demonstrated radiographic evidence of bone ingrowth. No implant was loose radiographically, and no implant was revised. Ceramic wear was not detectable in the thirty-seven hips in which the femoral head could be differentiated from the cup on radiographs. Periprosthetic osteolysis was not observed in any hip. A fracture of the alumina femoral head and a peripheral chip fracture of the alumina insert occurred in one hip following a motor-vehicle accident. The results of contemporary alumina-on-alumina total hip arthroplasty with a metal-backed socket and a cementless stem were encouraging after a minimum duration of follow-up of five years. We believe that these improved alumina-on-alumina bearing implants offer a promising option for younger, active patients.

P117 人工股関節用アルミナ骨頭の衝撃破壊挙動に関する研究(生体,ポスター講演3)

P117 人工股関節用アルミナ骨頭の衝撃破壊挙動に関する研究(生体,ポスター講演3)

Résultats à long terme du couple de frottement alumine/alumine sur 98 prothèses de hanche cimentées

Purpose of the study Mechanical failure in total hip arthroplasty is usually related to aseptic loosening itself related to wear particles as seen with polyethylene bearings. Alumina has bee proposed to avoid wear problems. In vitro and mid-term clinical studies have shown tribological advantages but early acetabular fixation remains an issue. Since alumina-on-alumina bearings are currently used with new fixation techniques, updated evaluations of older series are informative regarding the long-term tolerance of alumina in vivo. Material and methods We investigated 104 consecutive alumin-on-alumina cemented total hip arthroplasties (Cervaer-Osteal, Roissy, France) implanted 20 years ago in 81 patients (from 1979 to 1983). A32-mm alumina femoral head was used. The alumina acetabular socket and the titanium femoral stem were cemented. The Postel-Merle-d’Aubigné score was used for clinical evaluation. Radiological wear and development of osteolysis or loosening were noted for establishing actuarial curves. When accessible, histological samples from revision procedures were analyze. Results Six infected cases were not taken into account for data analysis. The average follow-up was 11 years, reaching 18 years in 38 cases. Twenty-three hips were revised for changing 23 acetabular sockets, 12 femoral heads, and one femoral stem. We noted one femoral head fracture, 24 definite acetabular loosenings, 12 probable acetabular loosenings, and 3 definite femoral loosenings. Radiological acetabular osteolysis was present in 4 cases, always limited to De Lee zone 1, and associated with loosening. Radiological wear was below eye detection. Periprosthetic tissue showed non-specific histological reactions to cement particles. Survival rate at 20 years was 62.8% [49.3-76.2%], in terms of revision 57.1% [42.5-71.7%] and 95.2% [89.9-100%] in terms of definite acetabular and femoral loosening. Discussion Besides the high rate of cemented fixation failure of the socket, loosened and non-loosened cases showed an excellent long-term tolerance of the alumina-on-alumina bearing with normal wear and osteolysis. This may also have protected the femoral component from complications. This study confirms in vivo the long-term tribological benefit of the alumina-on-alumina bearing in total hip arthroplasty and suggests that acetabular fixation should be improved to achieve full benefit.

Effect of alumina femoral heads on polyethylene wear in cemented total hip arthroplasty

We examined the behaviour of alumina ceramic heads in 156 cemented total hip arthroplasties, at a minimum follow-up of eight years. They were divided into three groups according to the size of the femoral head; 22, 26, and 28 mm. We measured polyethylene wear radiologically using a computer-aided technique. The linear wear rate of polyethylene sockets for the 28 mm heads was high (0.156 mm/year), whereas those for the 22 and 26 mm heads were relatively low (0.090 and 0.098 mm/year, respectively). Moreover, the surface roughness data of retrieved femoral heads clearly showed maintenance of an excellent surface finish of the current alumina. We conclude that the alumina ceramic femoral heads currently used are associated with a reduced rate of polyethylene wear.

Fatigue behaviour of fine-grained alumina hip-joint heads under normal walking conditions

In prosthetic applications, the reliability of implant materials over a period of thirty years is absolutely essential. Calculation of the lifetimes of alumina ceramic heads is generally made on the basis of experimental fatigue and slow crack growth tests using finite element analysis. This investigation is aimed at understanding the fatigue behaviour of fine-grained alumina heads of hip joints. The service conditions of cyclic stress experienced by hip joints during walking are used in evaluating the fatigue behaviour of alumina femoral heads. These femoral heads have successfully withstood 107 cycles at a maximum walking stress of 17.2 kN, which is equivalent to a body weight of 400 kg. The femoral heads did not exhibit any sub-critical crack growth at the maximum walking load of 10kN, indicating the quasi-infinite performance life in patients up to a body weight of 250 kg. The details of proof testing designed for evaluating the performance of femoral heads over 40 years are also presented.

Surface crystalline phases and nanoindentation hardness of explanted zirconia femoral heads.

One new and nine explanted zirconia femoral heads were studied using glancing angle X-ray diffraction, scanning electron microscopy, and nanoindentation hardness techniques. All starting zirconia implants consisted only of tetragonal zirconia polycrystals (TZP). For comparison, one explanted alumina femoral head was also studied. Evidence for a surface tetragonal-to-monoclinic zirconia phase transformation was observed in some implants, the extent of which was varied for different in-service conditions. A strong correlation was found between increasing transformation to the monoclinic phase and decreasing surface hardness. Microscopic investigations of some of the explanted femoral heads revealed ultra high molecular weight polyethylene and metallic transfer wear debris.

Massive wear in a CoCrMo head following the fracture of an alumina head.

The catastrophic fracture of an alumina femoral head is, fortunately, an increasingly rare event. The improvements made in the quality of modern ceramics, together with greater care in the manufacture of femoral stem cones and higher levels of expertise of the surgeons implanting the head itself, have significantly reduced this risk. A statistical analysis by Piconi (1) evaluates the percentage of breakage in modern ceramic heads at less than 0.02% (1 fracture every 5000 implants). We can therefore say that today the use of ceramic heads is highly reliable, but in certain cases, due mostly to negligence or technical errors, the fracture of the head is still possible. In these cases the problem we are facing is how to proceed in the revision of the implant, as simply replacing the head may lead to a further and more severe failure of the implant. (Hip International 2002; 1: 37-42).

Prevention of wear and osteolysis: alumina-on-alumina bearing.

Alumina-on-alumina bearings in total hip replacement have been used for 30 years. Excellent tribologic properties and extra low debris generation could, in theory, provide an answer to osteolysis. A review of the authors' experience with alumina-on-alumina bearings showed that, except in a few bearings that had been loose for a long time, osteolysis was not a problem. Although the cemented titanium stem and the alumina-on-alumina couple were not a problem, fixation of the socket had to be improved. To improve the socket fixation system and to avoid the use of a cemented titanium stem that may have created problems in the long-term, a new design was introduced in 1997. The current authors present the preliminary results of the first 96 hips with cementless fully-coated hydroxyapatite titanium alloy stems and sockets, 32-mm alumina femoral head, and alumina liner, both held with a Morse taper. Ninety-six consecutive hips in 89 patients (57 males, 32 females) with a median age of 46 years (range, 14-72 years) were analyzed. One socket was revised at 4 months because of poor primary stability in a patient with a severe acetabular fracture. One patient experienced a traumatic fracture of the implanted femur 3 weeks after surgery. The mean followup was 16 months (range, 4-38 months). One patient died from rupture of an aneurysm. Ninety-three hips in 86 patients were assessed regarding the clinical and radiologic ratings. Two patients (two hips) were interviewed by telephone. The Merle d'Aubigné rating system was 18 in 65 hips (59 patients), 17 in 25 hips (25 patients), and 16 in three hips (three patients) mainly related to a previous disability including limp, sciatic palsy, or stiffness. Examination of 93 available radiographs revealed no ostelolysis, no radiolucent lines at the last examination, and no subsidence. The level of excellent results, even in this young population, and lack of osteolysis and wear are encouraging, even if the followup is too short to allow any conclusions to be made.

Nanotribological Characterisation of Alumina Femoral Heads Using an Atomic Force Microscope

Nanotribological Characterisation of Alumina Femoral Heads Using an Atomic Force Microscope

Ceramic-on-polyethylene bearing surfaces in total hip arthroplasty. Seventeen to twenty-one-year results.

Polyethylene wear debris, and the resulting inflammatory response leading to osteolysis and loosening, is the primary mode of failure limiting the longevity of total hip replacements. Alternative bearing surfaces, including ceramic-on-polyethylene, have been investigated in an effort to decrease the amount of polyethylene wear debris. The purpose of this study was to evaluate the seventeen to twenty-one-year results of the use of ceramic-on-polyethylene total hip prostheses. Sixty-four total hip prostheses were implanted with cement, by one surgeon, in fifty-six patients from 1978 to 1981. The average age at the index arthroplasty was sixty-nine years (range, fifty-one to eighty-four years). The components consisted of a cemented Charnley-Müller stem with a 32-mm modular alumina femoral head and a cemented all-polyethylene acetabular component. All patients who retained the index prosthesis were assessed clinically with use of Harris hip scores and were evaluated radiographically at the time of the latest follow-up. At the time of this latest follow-up, of the original sixty-four implants, eighteen (28%) were still in place and five (8%) had been revised. The remaining forty-one implants were in patients who had died and were functioning well until the patient's death. No patient was lost to follow-up. Of the eighteen hips with an intact prosthesis in the surviving patients, seven had an excellent clinical result; nine, a good result; and two, a fair result. One asymptomatic hip had definite radiographic evidence of femoral loosening. No hip had definite signs of acetabular loosening or evidence of osteolysis. Survivorship analysis revealed that the probability of survival of the prostheses without revision was 95% at five years, 95% at ten years, 89% at fifteen years, and 79% at twenty years. The mean linear and volumetric polyethylene wear rates were 0.034 mm/yr and 28 mm(3)/yr, respectively. There were no fractures of the ceramic heads. Outstanding long-term clinical and radiographic results were attained despite the use of what are now considered substandard techniques (an inferior stem design, a 32-mm head, and first-generation cementing techniques). The wear rates in this study are lower than previously reported metal-on-polyethylene wear rates and are consistent with the lowest reported in vivo ceramic-on-polyethylene wear rates. These findings support the consideration of ceramic-on-polyethylene bearing surfaces in total hip arthroplasty.

Clinical Experience With Ceramics in Total Hip Replacement

As part of a search for better articulation in total hip prostheses, the decrease in the thickness of the socket in different total hip prostheses was measured in vivo. The wear rates of (1) RCH 1000 (molecular weight, 10(6)) socket gamma-irradiated with 100 Mrad articulating with a crude COP (stainless steel containing 20% cobalt and 0.01% phosphorous) metal femoral head; (2) RCH 1000 socket nonirradiated articulating with a crude COP femoral head; (3) RCH 1000 socket irradiated with 100 Mrad articulating with an alumina femoral head; (4) ultra high molecular weight polyethylene (molecular weight, 5-6 x 10(6)) socket articulating with an alumina femoral head; and (5) ultrahigh molecular weight polyethylene socket articulating with a stainless steel femoral head (T-28) were 0.06, 0.30, 0.06, 0.1 and 0.25 mm/year, respectively, in the authors' clinical cases. Alumina femoral heads were effective in decreasing wear of the polyethylene socket. However, the wear rates of gamma-irradiated sockets articulating with alumina and with metal femoral heads wear very low and were not different from each other. Regarding the relationship between wear rate and the thickness of the ultra high molecular weight polyethylene socket articulating with a 28 mm alumina femoral head, on radiographs, average wear rates of socket thicknesses of 7, 8, 9, 10 and 11 mm were 0.14, 0.15, 0.12, 0.06, and 0.08 mm/year, respectively. On measuring retrieved prostheses, average wear rates of 7, 8, 9 and 11 mm thickness sockets were 0.2, 0.19, 0.14, and 0.1 mm/year, respectively. The wear of sockets has been proven to be minimal in alumina femoral heads articulating with ultrahigh molecular weight polyethylene sockets thicker than 10 mm.

Ceramic femoral head retrieval data.

In the 1970s it was first realized that the properties of alumina ceramics could be exploited to provide better implants for orthopaedic applications. Applications depend on the fact that ceramics provided wear characteristics suitable for bearing surfaces in total hip replacement. Resultant orthopaedic use had more than 20 years' clinical success. To date more than 2.5 million alumina femoral heads have been implanted. Published reports of fracture rates of the alumina heads range between 0% for ceramics manufactured after 1990 and 13.4% for ceramics manufactured before 1990. These high fracture rates were caused by materials manufactured by companies that are not on the market today. These old aluminas had a low density, had a very coarse microstructure, and were not in compliance with specifications that are valid today. Materials scientists have substantially improved the mechanical strength of alumina. There are three generations of medical grade aluminas. The latest generation is an alumina that is hot isostatic pressed, laser marked, and proof tested. This material has been on the market since 1994. The fracture rates of the most commonly used ceramics have been analyzed by various groups, and are based on .5 million femoral heads to 1.5 million femoral heads. The fracture rate of ceramic Biolox femoral heads are 0.026 % for first generation alumina, 0.014% for second generation alumina, and 0.004% for femoral heads manufactured after 1994. Analyzing the clinical experience of more than 20 years, it can be concluded that all the improvements have produced reliable ceramic femoral heads.

Press-fit metal-backed alumina sockets: a minimum 5-year followup study.

Two hundred thirty-four consecutive alumina-on-alumina hip replacements using a press-fit metal-backed socket, performed on 214 patients (98 women, 116 men) have been reviewed. These included 201 primary procedures and 33 revision procedures. The median age of the patients at the time of surgery was 62 years (range, 21-83 years). Fourteen patients (16 hips) died from unrelated causes. Eleven patients (11 hips) underwent a total hip arthroplasty revision for recurrent dislocation (one hip), deep infection (two hips), fracture of alumina femoral head (one hip), persistent hip pain (one hip) and aseptic loosening (six hips). The survival rate after 9 years was 93.4% when revision of the prosthesis was considered the end point, and 97.4% if revision of the prosthesis for aseptic loosening was considered the end point. Results were assessed in the surviving patients with a minimal 5-year followup (170 patients, 184 hips). At the median followup of 7.8 years, the average Merle d'Aubigné and Postel score had improved from 11.9- to 17.7. Results were graded as excellent in 148 hips (80.5%), very good in 31 hips (17%), good in two hips (1%), and fair in three hips (1.5%). Radiologic data were documented for 134 patients (143 hips). Three sockets (2%) had a complete and nonprogressive radiolucent line less than 1-mm thick, one stem (0.7%) had lucencies involving five zones, and two stems (1.4%) had isolated femoral osteolysis. Neither component migration nor acetabular osteolysis were detected. A press-fit metal-backed socket may offer a good solution for alumina socket fixation when combined with a careful surgical technique of implantation.

Alumina Femoral Head Fracture: An in Vitro Study

A fracture of a ceramic femoral head is reported in this study. Fractures of ceramic femoral heads are uncommon and reports on this complication are rare. After 3 million cycles, on a twelve station hip simulator that tested alumina femoral head against polyethylene acetabular cup, fracture of the ceramic ball was observed. The retrieved specimen consisted of three large ceramic fragments from the same ceramic femoral head, a polyethylene acetabular cup and a stainless steel jig. Careful and detailed examination of the removed components was made. The fracture of the ceramic ball resulted in damage to the metal taper of the jig component which was fixed into the simulator.

An in vitro investigation of diamond-like carbon as a femoral head coating.

Wear of polyethylene acetabular components of hip implants is a significant clinical problem. In prosthetic hip surgery, polyethylene wear is identified as a factor that limits the life of the implant; it is known that the production of debris can cause adverse tissue reactions that may lead to extensive bone loss around the implant, and consequently loosening of the fixation. A new class of so-called Diamond-Like Carbon coatings, applied to titanium femoral heads was compared to ceramic and metallic heads in terms of wear behavior against UHMWPE using a hip joint simulator with a bovine calf serum lubricant. A thin film of Diamond-Like Carbon was deposited directly onto titanium (Ti6Al4V) head using chemical vapor deposition. The wear of polyethylene coupled with Diamond-Like Carbon coated femoral heads was comparable to that obtained with the polyethylene coupled with commercial alumina femoral heads.

Poor eight-year survival of cemented zirconia-polyethylene total hip replacements

Between January 1988 and January 1991 we performed 100 consecutive cemented total hip replacements using a zirconia head, a titanium alloy stem and a polyethylene cup. We reviewed 78 of these hips in 61 patients in detail at a mean of 5.8 years (1 to 9). Aseptic loosening was seen in 11 hips (14%). Eight needed revision. In total, 37 cups (47.5%) showed radiolucent lines, all at the cement-bone interface, with 18 (23%) involving all the interface. Of the 78 femoral implants, 17 (21.7%) showed radiolucent lines, and two, which had a complete line of more than 1 mm thick, definite endocortical osteolyses. There was also an abnormally high incidence of osteolysis of more than 2 mm at the calcar. Survivorship analysis showed that only 63% were in situ at eight years. These worrying results led us to abandon the use of zirconia heads, since at the same hospital, using the same femoral stem, cement and polyethylene cup, but with alumina femoral heads, the survival rate was 93% at nine years. We discuss the possible reasons for the poor performance of zirconia ceramic.

Tribological investigations of the wear couple alumina–CFRP for total hip replacement

Wear debris is the main reason for aseptic loosening in total hip. Most troublesome is the wear of polyethylene cups. Ceramic femoral heads were introduced about 20 years ago. The combination ceramic-on-polyethylene reduces the wear rate and the loosening rate. But cups of polyethylene are still the weakest link in a hip prosthesis. Carbon fibre reinforced plastic (CFRP) was proposed as an alternative for polyethylene. Various test were performed to study the combination metal-on-CFRP, zirconia-on-CFRP, and alumina-on-CFRP. The simulator tests showed that the wear rate of alumina-on-CFRP is in the order of 1–3 μm per year. Based on investigation of retrieved implants the wear rate is 6.3 μm per year. Based on these results the combination alumina femoral heads (Biolox ®-forte) and CFRP cups (Caproman ®) could be approved for total hip replacement.

The fallacy of evaluating biomaterial wear-rates with water as lubricant: a hip simulator study of alumina-PTFE nd CoCr-PTFE combinations.

Controversy surrounds wear data from hip-simulator studies, whether from the choice of lubricants or other parameters such as the particular biomaterial combinations used, and whether any such interactions could bias the resulting wear predictions. To investigate these phenomena, we studied the wear performance of CoCr and alumina femoral heads, in water and serum-based lubricants, using as our standard the polytetrafluoroethylene wear data derived clinically by Charnley. To model Charnley's clinical experience, PTFE acetabular cups were used in sets of three each with each size of femoral head for 22.25, 28, and 42-mm diameters in a nine-channel hip simulator. From the serum-based tests, the CoCr-PTFE wear data were consistently linear with duration of test, exhibited very large wear rates of 3,000-8,400 mm3/10(6), cycles had a precision within +/- 4% for each set of three cups, and copious amounts of small particulate were clearly seen circulating. The wear data clearly demonstrated Charnley's thesis that volume of wear increased with regard to size of femoral head. From the water-based tests, the CoCr-PTFE wear data were nonlinear with duration of test, had much reduced wear rates compared to the serum tests, lost the clinical relationship with ball size, and precision deteriorated to +/- 27% for each set. The wear debris appeared as 1-2 cm long ribbons which floated to the surface. For the alumina-PTFE combination in serum, the wear data appeared identical in performance to the CoCr-PTFE data in serum. Thus, the PTFE wear rates were not sensitive to the choice of femoral-head material. The most surprising outcome in this study was the zero-wear performance of the ceramic-PTFE combination in water. This contrasted remarkably with the large wear rates established for the same combinations run in serum. The zero-wear performance of the ceramic-PTFE combination in water was unexpected, but a similar phenomenon was noted in published simulator tests of ceramic-UHMWPE run in water. It now seems likely that such data may reflect the capricious behavior of water lubrication rather than any other variables under evaluation. The water-based experiments clearly favored the ceramic's superior tribological performance and placed metal bearings at a decided disadvantage. Therefore, for an in vitro simulation of materials wear-ranking of clinical relevance, it may be advisable to use a serum-based lubricant.

The fallacy of evaluating biomaterial wear‐rates with water as lubricant: A hip simulator study of alumina‐PTFE and CoCr‐PTFE combinations

Controversy surrounds wear data from hip-simulator studies, whether from the choice of lubricants or other parameters such as the particular biomaterial combinations used, and whether any such interactions could bias the resulting wear predictions. To investigate these phenomena, we studied the wear performance of CoCr and alumina femoral heads, in water and serum-based lubricants, using as our standard the polytetrafluoroethylene wear data derived clinically by Charnley. To model Charnley's clinical experience, PTFE acetabular cups were used in sets of three each with each size of femoral head for 22.25, 28, and 42-mm diameters in a nine-channel hip simulator. From the serum-based tests, the CoCr-PTFE wear data were consistently linear with duration of test, exhibited very large wear rates of 3,000–8,400 mm3/106, cycles had a precision within ±4% for each set of three cups, and copious amounts of small particulate were clearly seen circulating. The wear data clearly demonstrated Charnley's thesis that volume of wear increased with regard to size of femoral head. From the water-based tests, the CoCr-PTFE wear data were nonlinear with duration of test, had much reduced wear rates compared to the serum tests, lost the clinical relationship with ball size, and precision deteriorated to ±27% for each set. The wear debris appeared as 1–2 cm long ribbons which floated to the surface. For the alumina-PTFE combination in serum, the wear data appeared identical in performance to the CoCr-PTFE data in serum. Thus, the PTFE wear rates were not sensitive to the choice of femoral-head material. The most surprising outcome in this study was the zero-wear performance of the ceramic-PTFE combination in water. This contrasted remarkably with the large wear rates established for the same combinations run in serum. The zero-wear performance of the ceramic-PTFE combination in water was unexpected, but a similar phenomenon was noted in published simulator tests of ceramic-UHMWPE run in water. It now seems likely that such data may reflect the capricious behavior of water lubrication rather than any other variables under evaluation. The water-based experiments clearly favored the ceramic's superior tribological performance and placed metal bearings at a decided disadvantage. Therefore, for an in vitro simulation of materials wear-ranking of clinical relevance, it may be advisable to use a serum-based lubricant. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 229–233, 1998.