Aims. This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). Methods. Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years’ follow-up. Results. Patients in Group C were associated with increased mean liner wear rates compared to patients in Group A (0.133 mm/yr (SD 0.21) vs 0.031 mm/yr (SD 0.07), respectively; p < 0.001) and Group B (0.133 mm/yr (SD 0.21) vs 0.022 mm/yr (SD 0.05), respectively; p < 0.001) at ten years’ follow-up. Patients in Group C were also associated with increased risk of osteolysis and aseptic loosening requiring revision surgery, compared with patients in Group A (7/133 vs 0/133, respectively; p = 0.007) and Group B (7/133 vs 0/135, respectively; p = 0.007). There was a non-statistically significant trend towards increased mean liner wear rates in Group A compared with Group B (0.031 mm/yr (SD 0.07) vs 0.022 mm/yr (SD 0.05), respectively; p = 0.128). All three groups were statistically comparable preoperatively and at ten years’ follow-up when measuring normalized Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.410), 36-Item Short Form Health Survey (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p = 0.451). Conclusion. The use of UHMWPE was associated with progressively increased annual liner wear rates after THA compared to XLPE. At ten years’ follow-up, the group receiving UHMWPE demonstrated an increased incidence of osteolysis and aseptic loosening requiring revision surgery compared to XLPE. Femoral heads composed of OxZr were associated with trend towards reduced wear rates compared to CoCr, but this did not reach statistical significance and did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two femoral head components. Cite this article: Bone Joint J 2022;104-B(7):833–843

We have reviewed 70 patients with bilateral simultaneous total hip arthroplasties to determine the rate of failure and to compare polyethylene wear and osteolysis between an implant with a cobalt-chrome head and Hylamer liner with that of a zirconia head and Hylamer liner. The mean thickness of the polyethylene liner was 11.0 mm (8.8 to 12.2) in the hip with a zirconia head and 10.7 mm (8.8 to 12.2) in that with a cobalt-chrome head. At follow-up at 6.4 years no acetabular or femoral component had been revised for aseptic loosening and no acetabular or femoral component was loose according to radiological criteria in both the cemented and cementless groups. The mean rate of linear wear and annual wear rate were highest in the 22 mm zirconia femoral head (1.25 mm (SD 1.05) and 0.21 mm (SD 0.18), respectively) and lowest in the 22 mm cobalt-chrome femoral head (0.70 mm (SD 0.39) and 0.12 mm (SD 0.07), respectively). The mean volumetric wear was highest in the 28 mm zirconia femoral head (730.79 mm. 3. ) and lowest in the 22 mm cobalt-chrome femoral head (264.67 mm. 3. ), but if the results were compared by size of the femoral head and type of material there was no statistical difference (p > 0.05). Sequential measurements of annual wear showed that the zirconia femoral head had a relatively higher rate of penetration than the cobalt-chrome head over the first three years; thereafter the rate of wear was reduced and compared favourably with that of cobalt-chrome heads. There was a statistically significant relationship between the wear of the polyethylene liner and the age of the patient, male gender and the degree of abduction angle of the cup, but not diagnosis, weight, hip score, range of movement, or amount of anteversion. Osteolysis was identified on both sides of the acetabulum in six patients (9%). Of 12 hips with acetabular osteolysis, six had a 28 mm cobalt-chrome femoral head and the remaining six a 28 mm zirconia head. Osteolysis was observed in zones 1A and 7A of the femur in two hips (3%) with a 28 mm zirconia head (cemented hip) and in four (6%) with a 28 mm cobalt-chrome femoral head (cementless hip). Our findings suggest that although the performance of a zirconia femoral head with a Hylamer liner was not statistically different from that of a cobalt-chrome femoral head and Hylamer liner, there was a trend for the zirconia head to be worse than the cobalt-chrome femoral head

At yearly intervals we compared the radiological wear characteristics of 81 alumina ceramic femoral heads with a well-matched group of 43 cobalt-chrome femoral heads. Using a computer-assisted measurement system we assessed two-dimensional penetration of the head into the polyethylene liner. We used linear regression analysis of temporal data of the penetration of the head to calculate the true rates of polyethylene wear for both groups. At a mean of seven years the true rate of wear of the ceramic group was slightly greater (0.09 mm/year, SD 0.07) than that of the cobalt-chrome group (0.07 mm/year, SD 0.04). Despite the numerous theoretical advantages of ceramic over cobalt-chrome femoral heads, the wear performance in vivo of these components was similar

Fifty-four cobalt-chrome alloy femoral heads were retrieved at revision surgery or at post-mortem; 23 came from uncemented, eight from hybrid and 23 from cemented hip arthroplasties. The uncemented and hybrid implants had porous coating, metal backing and modular femoral heads; with one exception none of the cemented implants had any of these. Twenty-five of the 31 heads from uncemented and hybrid arthroplasties, and 11 of the 23 heads from cemented arthroplasties showed surface damage involving more than 25% of the surface. Scanning electron microscopy revealed multidirectional fine scratches 1 micron to 10 microns in depth and width which appeared to have been made by fine, hard particles. There was a higher rate of such damage in the uncemented and hybrid arthroplasties than in the cemented implants, suggesting that the abrasive particles were mainly released from the metal, rather than from the cement or polyethylene components of the implants

We studied the wear generated by motion between polished and shot-blasted titanium-alloy (Ti-6Al-4V) or cobalt-chrome alloy (Co-Cr) surfaces and cortical bone in vitro. Semicircular sections of human proximal femoral cortex were reamed to fit metal cylinders of each alloy. The cylinders were then fitted in the bone, loaded and rotated in physiological saline. Ti-alloy resulted in more wear both of the bone and of the metal than did Co-Cr alloy. Metal wear was reduced and bone wear was increased by shot-blasting, a procedure which introduces surface residual stresses and roughens the metal surface. We conclude that when there is gross motion between a metal implant and bone, Ti-alloy is likely to generate more wear debris than Co-Cr alloy. The least wear both of bone and of metal was produced by polished Co-Cr

We implanted 57 uncemented cobalt-chrome porous-coated collarless femoral components into 51 patients (mean age 49 years). At review, five to eight years postoperatively, good or excellent results were recorded in 70% by the Mayo Clinic hip evaluation and in 84% by the Harris hip score. Revision for aseptic loosening of the femoral stem was necessary in only one hip. Thigh pain diminished with time and was present in only two hips at the time of review. Endosteal bone formation was seen at the junction of the smooth and the porous segments of the stem in 94% of hips and in 60% it continued after three years. In 90% of hips, proximal femoral atrophy did not progress after three years. Discontinuous radiolucent lines were seen around 30% of stems, most commonly in zones I, IV and VII. They were not progressive in 94% and their presence did not correlate with the clinical outcome

Aims. A recent report from France suggested an association between the use of cobalt-chrome (CoCr) femoral heads in total hip arthroplasties (THAs) and an increased risk of dilated cardiomyopathy and heart failure. CoCr is a commonly used material in orthopaedic implants. If the reported association is causal, the consequences would be significant given the millions of joint arthroplasties and other orthopaedic procedures in which CoCr is used annually. We examined whether CoCr-containing THAs were associated with an increased risk of all-cause mortality, heart outcomes, cancer, and neurodegenerative disorders in a large national database. Methods. Data from the National Joint Registry was linked to NHS English hospital inpatient episodes for 374,359 primary THAs with up to 14.5 years' follow-up. We excluded any patients with bilateral THAs, knee arthroplasties, indications other than osteoarthritis, aged under 55 years, and diagnosis of one or more outcome of interest before THA. Implants were grouped as either containing CoCr or not containing CoCr. The association between implant construct and the risk of all-cause mortality and incident heart failure, cancer, and neurodegenerative disorders was examined. Results. There were 158,677 individuals (42.4%) with an implant containing CoCr. There were 47,963 deaths, 27,332 heart outcomes, 35,720 cancers, and 22,025 neurodegenerative disorders. There was no evidence of an association between patients with CoCr implants and higher rates of any of the outcomes. Conclusion. CoCr-containing THAs did not have an increased risk of all-cause mortality, or clinically meaningful heart outcomes, cancer, or neurodegenerative disorders into the second decade post-implantation. Our findings will help reassure clinicians and the increasing number of patients receiving primary THA worldwide that the use of CoCr-containing implants is not associated with significant adverse systemic effects. Cite this article: Bone Joint J 2022;104-B(3):359–367

Aims. We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement. Methods. Gentamicin-loaded UHMWPE was prepared using phase-separated compression moulding, and its drug elution kinetics, antibacterial, mechanical, and wear properties were compared with those of conventional gentamicin-loaded bone cement. Results. Gentamicin-loaded UHMWPE tibial components not only eradicated planktonic Staphylococcus aureus, but also prevented colonization of both femoral and tibial components. The proposed spacer possesses far superior mechanical and wear properties when compared with conventional bone cement spacers. Conclusion. The proposed gentamicin-eluting UHMWPE spacer can provide antibacterial efficacy comparable with currently used bone cement spacers, while overcoming their drawbacks. The novel spacer proposed here has the potential to drastically reduce complications associated with currently used bone cement spacers and substantially improve patients’ quality of life during the treatment. Cite this article: Bone Joint J 2020;102-B(6 Supple A):151–157

Aims. This combined clinical and in vitro study aimed to determine the incidence of liner malseating in modular dual mobility (MDM) constructs in primary total hip arthroplasties (THAs) from a large volume arthroplasty centre, and determine whether malseating increases the potential for fretting and corrosion at the modular metal interface in malseated MDM constructs using a simulated corrosion chamber. Methods. For the clinical arm of the study, observers independently reviewed postoperative radiographs of 551 primary THAs using MDM constructs from a single manufacturer over a three-year period, to identify the incidence of MDM liner-shell malseating. Multivariable logistic regression analysis was performed to identify risk factors including age, sex, body mass index (BMI), cup design, cup size, and the MDM case volume of the surgeon. For the in vitro arm, six pristine MDM implants with cobalt-chrome liners were tested in a simulated corrosion chamber. Three were well-seated and three were malseated with 6° of canting. The liner-shell couples underwent cyclic loading of increasing magnitudes. Fretting current was measured throughout testing and the onset of fretting load was determined by analyzing the increase in average current. Results. The radiological review identified that 32 of 551 MDM liners (5.8%) were malseated. Malseating was noted in all of the three different cup designs. The incidence of malseating was significantly higher in low-volume MDM surgeons than high-volume MDM surgeons (p < 0.001). Pristine well-seated liners showed significantly lower fretting current values at all peak loads greater than 800 N (p < 0.044). Malseated liner-shell couples had lower fretting onset loads at 2,400 N. Conclusion. MDM malseating remains an issue that can occur in at least one in 20 patients at a high-volume arthroplasty centre. The onset of fretting and increased fretting current throughout loading cycles suggests susceptibility to corrosion when this occurs. These results support the hypothesis that malseated liners may be at risk for fretting corrosion. Clinicians should be aware of this phenomenon. Cite this article: Bone Joint J 2020;102-B(7 Supple B):20–26

Complications involving the patellofemoral joint, caused by malrotation of the femoral component during total knee replacement, are an important cause of persistent pain and failure leading to revision surgery. The aim of this study was to determine and quantify the influence of femoral component malrotation on patellofemoral wear, and to determine whether or not there is a difference in the rate of wear of the patellar component when articulated against oxidised zirconium (OxZr) and cobalt-chrome (CoCr) components. An in vitro method was used to simulate patellar maltracking for both materials. Both rates of wear and changes in height on the patellar articular surface were measured. The mean rates of wear measured were very small compared to standard tibiofemoral wear rates. When data for each femoral component material were pooled, the mean rate of wear was 0.19 mm. 3. /Mcycle (. sd. 0.21) for OxZr and 0.34 mm. 3. /Mcycle (. sd. 0.335) for CoCr. The largest change in height on each patella varied from -0.05 mm to -0.33 mm over the different configurations. The results suggest that patellar maltracking due to an internally rotated femoral component leads to an increased mean patellar wear. Although not statistically significant, the mean wear production may be lower for OxZr than for CoCr components

We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and four women) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns

Aims. The purpose of this study was to compare the long-term results of primary total hip arthroplasty (THA) in young patients using either a conventional (CPE) or a highly cross-linked (HXLPE) polyethylene liner in terms of functional outcome, incidence of osteolysis, radiological wear and rate of revision. Methods. We included all patients between the ages of 45 and 65 years who, between January 2000 and December 2001, had undergone a primary THA for osteoarthritis at our hospital using a CPE or HXLPE acetabular liner and a 28 mm cobalt-chrome femoral head. . From a total of 160 patients, 158 (177 hips) were available for review (CPE 89; XLPE 88). The mean age, body mass index (BMI) and follow-up in each group were: CPE: 56.8 years (46 to 65); 30.7 kg/m. 2. (19 to 58); 13.2 years (2.1 to 14.7) and HXLPE: 55.6 years (45 to 65); BMI: 30 kg/m. 2. (18 to 51); 13.1 years (5.7 to 14.4). Results. The mean Harris hip score (HHS) at final follow-up was 89.3 for the CPE group and 90.9 for the HXLPE group (p = 0.078). Osteolysis was present around 15 acetabular (17%) and 16 femoral (18%) components in the CPE hips compared with none (0%) in the HXLPE hips. The mean radiological linear wear of the CPE liners was 0.11 mm/year compared with 0.035 mm/year for the HXLPE liners (p = 0.006). The cumulative implant survival, with revision for polyethylene wear as the endpoint, was 86% (95% confidence interval 78 to 94) in the CPE group and 100% in the HXLPE group at 13 years (numbers at risk at 13 years - CPE: 65, XLPE: 61). Discussion. This study shows that HXLPE liners are associated with significantly less osteolysis and a lower rate of revision THA than CPE liners at long-term follow-up. Take home message: The findings of this study highlight the clinical benefits of using HXLPE liners in THA and support the routine use of the material in order to improve implant longevity and to decrease the number of patients needing revision for aseptic osteolysis. . Cite this article: Bone Joint J 2016;98-B:28–32

Aims

Uncemented implants are now commonly used at reimplantation of a two-stage revision total hip arthoplasty (THA) following periprosthetic joint infection (PJI). However, there is a paucity of data on the performance of the most commonly used uncemented femoral implants – modular fluted tapered (MFT) femoral components – in this setting. This study evaluated implant survival, radiological results, and clinical outcomes in a large cohort of reimplantation THAs using MFT components.

1. Two of the three metals at present in use in orthopaedic surgery have been studied to assess their tendency to cause wound reactions. 2. Cobalt-chrome alloy proved to be the better, the incidence of obligatory plate removal being at most 3 per cent. Visible corrosion in this metal never occurred. 3. 18/8 Mo stainless steel proved to be the poorer, the incidence of obligatory plate removal being 20 per cent. Visible corrosion of the metal is estimated to have occurred in about 5 per cent of screws inserted. 4. Regardless of such accelerating factors as metallic transfer, 18/8 Mo steel may have to be accepted as inherently more susceptible to corrosion than is cobalt-chrome alloy. 5. The qualities of two other stainless steels also became evident. Previous work describing the very bad situation arising from the use of EMS was confirmed. By contrast, a steel that was in use before 1951 gave little trouble. This steel was probably FSL

Reports of differing failure rates of total hip prostheses made of various metals prompted us to measure the size of metallic and polyethylene particulate debris around failed cemented arthroplasties. We used an isolation method, in which metallic debris was extracted from the tissues, and a non-isolation method of routine preparation for light and electron microscopy. Specimens were taken from 30 cases in which the femoral component was of titanium alloy (10), cobalt-chrome alloy (10), or stainless steel (10). The mean size of metallic particles with the isolation method was 0.8 to 1.0 microns by 1.5 to 1.8 microns. The non-isolation method gave a significantly smaller mean size of 0.3 to 0.4 microns by 0.6 to 0.7 microns. For each technique the particle sizes of the three metals were similar. The mean size of polyethylene particles was 2 to 4 microns by 8 to 13 microns. They were larger in tissue retrieved from failed titanium-alloy implants than from cobalt-chrome and stainless-steel implants. Our results suggest that factors other than the size of the metal particles, such as the constituents of the alloy, and the amount and speed of generation of debris, may be more important in the failure of hip replacements

Aims

Oxidized zirconium (OxZi) and highly cross-linked polyethylene (HXLPE) were developed to minimize wear and risk of osteolysis in total hip arthroplasty (THA). However, retrieval studies have shown that scratched femoral heads may lead to runaway wear, and few reports of long-term results have been published. The purpose of this investigation is to report minimum ten-year wear rates and clinical outcomes of THA with OxZi femoral heads on HXLPE, and to compare them with a retrospective control group of cobalt chrome (CoCr) or ceramic heads on HXLPE.

Aims

Contemporary outcomes of primary total hip arthroplasties (THAs) with highly cross-linked polyethylene (HXLPE) liners in patients with inflammatory arthritis have not been well studied. This study examined the implant survivorship, complications, radiological results, and clinical outcomes of THA in patients with inflammatory arthritis.