Wear Of Conventional Polyethylene Research Articles

Minimum 30-Year Results of Bilaterally Implanted Cemented and Cementless Total Hip Arthroplasty in Patients Younger Than 50 Years

BackgroundThe rate of failure of cemented and cementless total hip arthroplasty (THA) in younger patients is higher than that in elderly patients. The purpose of this study is to document the long-term clinical results of THA with the so-called third-generation cementing and the results of second-generation cementless THA in patients <50 years of age. MethodsThis study included 106 patients who had had bilateral THA with a cemented stem in one hip and a cementless stem in the other. There were 78 men and 28 women. Their mean age was 47 years (range, 21-49). The average follow-up duration was 31 years (range, 30-32.5). ResultsThere were similar mean Harris Hip Scores (90 versus 91 points) between the groups at the final follow-up. Forty-six acetabular components (43%) in the cemented group and 48 acetabular components (45%) in the cementless group were revised. Five femoral components (5%) in the cemented group and 4 femoral components (4%) in the cementless group were revised. Survivorship of the acetabular component at 30.8 years was similar in both groups (57% in the cemented group versus 55% in the cementless group). Survivorship of the femoral component at 30.8 years was also similar in both groups (95% in the cemented group versus 96% in the cementless group). ConclusionLong-term fixation of the cemented or cementless femoral stem was outstanding. There was a high rate of the acetabular component revision due to conventional polyethylene wear and periacetabular osteolysis in both hybrid and fully cementless THA groups.

Total Articular Knee Replacement Using Polyurethane.

This study reviewed the early use of polyurethane for total knee resurfacing, the long-term results of polycarbonate urethane (PCU) for total knee replacement and conducted wear simulator testing of PCU. In 1959 and 1960, 10 patients underwent total articular polyurethane knee replacement (polyethylene was not available). The polyurethane was placed on the articular surface of the femur with metal surfaces on the tibia and patella. In 1996 and 1997, four patients received a newer PCU tibial insert in revision procedures; all had well-fixed prostheses, but no revision polyethylene implants were available. In addition, this study evaluated six new PCU tibial inserts in a 10-million cycle (Mc) wear simulator. All 10 of the early knees performed well clinically and 2 knees were functional for more than 30 years. Of the four more recent patients, all knees remain functional at more than 20 years' follow-up with no signs of wear or osteolysis. Wear simulator testing found mean material loss of 14.2 mg/Mc which equates to a volumetric wear of 11.9 mg/Mc, similar to the wear of conventional polyethylene. Polyurethane performs well as conventional polyethylene but not better than current cross-linked polyethylene tibial inserts. Its large wear particles (mean, 11 µm) and biocompatibility are less likely to cause an inflammatory response leading to pain and bone loss. Newer, superior polyurethanes can again be considered a candidate material for the tibial insert of a total knee replacement. A larger study may be able to validate polyurethane as an alternative material for joint replacement.

No Difference in Conventional Polyethylene Wear Between Yttria-stabilized Zirconia and Cobalt-chromium-molybdenum Femoral Heads at 10Years.

Concerns have arisen regarding deterioration of wear properties of yttria-stabilized zirconia (YSZ) femoral head on conventional polyethylene (PE) bearings due to YSZ phase transformation. The purpose of this study was to determine if there is a difference in long-term PE wear properties between YSZ and cobalt-chromium-molybdenum (Co-Cr-Mo) femoral heads. Ten-year radiographic wear assessment was performed on a cohort of patients enrolled in a prospective randomized clinical trial comparing total hip arthroplasty with YSZ or Co-Cr-Mo femoral heads on conventional, non-cross-linked PE. PE linear wear, annualized wear, and steady-state wear rates remained low and similar between groups. No cases of osteolysis were observed. Measured conventional PE wear was similar between YSZ and Co-Cr-Mo femoral heads with the steady-state wear rates for both remaining below the generally accepted threshold at which osteolysis typically occurs. Whether clinically relevant phase transformation with YSZ femoral heads occurs is uncertain; however, the use of YSZ femoral heads in this study was not associated with increased PE wear, osteolysis, or deterioration of wear properties.

Effect of Acetabular Position on Polyethylene Liner Wear Measured Using Simultaneous Biplanar Acquisition

BackgroundStudies that have previously examined the relationship between acetabular component inclination angle and polyethylene wear have shown increased wear of conventional polyethylene with high inclination angles. To date, there are no long-term in vivo studies examining the correlation between cup position and polyethylene wear with highly crosslinked polyethylene. MethodsAn institutional arthroplasty database was used to identify patients who had metal-on-highly crosslinked polyethylene primary total hip arthroplasty using the same component design with a minimum follow-up of 10 years. A modified radiostereometric analysis examination setup was utilized, recreating standard anteroposterior and cross-table lateral examinations in a single stereo radiostereometric analysis acquisition. The same radiographs were used to measure inclination angle and anteversion. ResultsA total of 43 hips were included for analysis in this study. Average follow-up was 12.3 ± 1.2 years. The average linear wear rate was calculated to be 0.066 ± 0.066 mm/y. Inclination angle was not correlated with polyethylene wear rate (P = .82). Anteversion was also not correlated with polyethylene wear rate (P = .11). ConclusionAt long-term follow-up of >10 years, highly crosslinked polyethylene has a very low wear rate. This excellent tribology is independent of acetabular position. The low wear rate highlights the excellent results of metal on highly crosslinked polyethylene, and supports its use in total hip arthroplasty.

Constrained liners, dual mobility or large diameter heads to avoid dislocation in THA.

Dislocation remains a common cause of failure after total hip arthroplasty. The limitations of existing approaches to address instability have led to the development of powerfull options: constrained liners, dual mobility and large heads. These implant-related options have proven to be very efficient, but have raised concerns.With constrained liners, restricted range of motion (ROM) is responsible for impingement leading to high likelihood of failure, depending on the design, with various failure modes.Improvements of the bearing materials have addressed some of the concerns about increased volumetric wear of conventional polyethylene and offer an option to reduce instability: large diameter heads have the advantage of increased ROM before impingement, increased head-neck ratio, and jump distance. Highly cross-linked polyethylene helps address the risk for increased wear, and also large heads provide improved stability without the risk of mechanical failures observed with constrained liners. However, the increase of the head size remains limited as reducing the thickness of the liner may lead to fractures. In addition, the jump distance decreases as the cup abduction increases.The dual mobility concept simultaneously attempts to address head-neck ratio, constraint, and jump distance. Despite the need for longer follow-up, concerns raised about potential increased wear and intra-prosthetic dislocation with first generation implants have been addressed with modern designs.With a dramatic increase of the head-neck ratio whilst reducing the risk of mechanical failure or excessive wear, dual mobility THA outperforms large diameter heads and constrained liners at 10 years follow-up. For these reasons, dual mobility continues to gain interest worldwide and is becoming the most popular option to manage instability.Cite this article: Guyen O. Constrained liners, dual mobility or large diameter heads to avoid dislocation in THA. EFORT Open Rev 2016;1:197-204. DOI: 10.1302/2058-5241.1.000054.

Ceramic-on-ceramic THA Implants in Patients Younger Than 20 Years.

Poor survival of THA implants in very young patients has been attributed to use of cemented implants, wear of conventional polyethylene, and the presence of morphologic deformities in the proximal femur or in the acetabulum. Few studies have reported the long-term results of ceramic-on-ceramic implants in THAs in patients younger than 20 years. We determined: (1) the proportion of patients who experienced complications related to the ceramic bearing (squeaking, fracture); (2) the survivorship free from loosening and free from revision for any reason; (3) whether patients with osteonecrosis had inferior survivorship compared with patients whose surgical indication was all other diagnoses including sequelae of pediatric hip disorders (developmental dysplasia of the hip, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis); and (4) clinical function. Between 1979 and 2013, we performed 113 primary THAs in 91 patients younger than 20 years at the time of surgery. Of those, 105 THAs (83 patients) were done with ceramic-on-ceramic bearings (91% of the 91 patients); during that period, a ceramic-on-ceramic bearing couple was indicated in all patients younger than 20 years. In eight patients (eight hips), a cemented polyethylene cup was implanted because the diameter of the acetabulum was smaller than the smallest available ceramic cup (46 mm), or because adequate fixation of a ceramic press-fit cup could not be achieved despite careful reaming of the acetabulum. The most common diagnosis indicating THA was avascular necrosis of the femoral head (56.2%; 59 hips). Thirty-five patients (40 hips) had undergone previous operations before the replacement. Three patients (4%; four hips) died from unrelated causes, nine patients (11%; 13 hips) were lost to followup, and four patients (five hips) had a followup greater than 8.5 years but have not been seen in the last 5 years. Patients were assessed clinically (using the Merle d'Aubigne-Postel score, Hip disability and Osteoarthritis Outcome score (HOOS), and the SF-12(®) Health Survey, and radiographically for signs of radiolucencies, subsidence, or osteolysis on plain films. The mean followup was 8.8 ± 6.1 years (range, 2-34.4 years). Five patients experienced transient noise generation, defined as a snap in four patients and squeaking in one. Seventeen hips underwent revision surgery-16 for aseptic loosening and one for septic loosening. The implant survival rate at 10 years with aseptic loosening as the endpoint was 90.3% (95% CI, 82.4%-98.9%). No hip had acetabular or femoral osteolysis. Survivorship in patients with osteonecrosis did not differ from survivorship in patients with other diagnoses. The Merle d'Aubigne-Postel score increased from 10.1 ± 4.0 to 17.6 ± 1.1 (p < 0.01); the mean HOOS score was 79.3 ± 13.8 (range, 50.6-100); the mean SF-12(®) physical and mental component scores were 48.1 ± 7.9 (range, 21.4-57.6), and 47.4 ± 12.2 (range, 24.5-99.4), respectively. We found that patient-reported outcomes scores improved in most patients undergoing THA in this very young study group. Underlying diagnosis did not affect long-term survivorship. However, the revision-free survival rate at 10 years is lower than published estimates in older patients, and with 11% of patients lost to followup, our estimates may represent a best-case scenario. Therefore, we believe THA should be performed as a last resort in this population. Level IV, therapeutic study.

The jumbo cup: Easiest and safest solution

Jumbo cups can be used to address many acetabular revision cases with bone loss. The technique of implantation is relatively straight forward, and there is the potential to maximize bone-to-cup surface area, approximate the natural hip center, and to obtain a construct that allows immediate weight bearing. Experience from multiple sources has demonstrated survivorship up to 83% at 20 years, limited mostly by the wear of conventional polyethylene. A contraindication to this method is irradiated bone and a limitation is restoration of peripheral acetabular bone stock, which could compromise further revision surgery.

CORR Insights(®): Wear and Osteolysis of Highly Crosslinked Polyethylene at 10 to 14 Years: The Effect of Femoral Head Size.

P olyethylene has been in use as a bearing surface for hip arthroplasty for more than 60 years and many past attempts to alter its structure and improve performance have been met with complications and controversy. Increased wear of conventional polyethylene, associated periprosthetic bone loss, and the need for revision surgery peaked in the 1990s. This was in part due to younger and more active patients receiving THA, the use of larger diameter femoral heads, and also related to issues with first-generation cementless sockets. It has been generally accepted that reducing liner wear below 0.1 mm and volumetric wear below 80 cubic mm per year reduces the risk of osteolysis and can increase the longevity of hip arthroplasty. First-generation highly crosslinked polyethylenes (HXLPEs) were developed to increase abrasive wear resistance and address these issues. The major controversies and concerns with these new materials include decreased polyethylene fatigued strength, potential for in vivo oxidation, implant fracture with thin or mapositioned liners, the use of larger diameter femoral heads, and polyethylene particulate size and shape. While simulator studies predicted substantial wear reductions, including low wear for larger diameter femoral heads, the ultimate test for implant performance and survivorship remains in vivo analysis.

Effect of hydroxyapatite coating on the radio-clinical results of a grit-blasted titanium alloy femoral taper. A case-control study of 198 cementless primary total hip arthroplasty with the Alloclassic™ system

BackgroundThe effect of hydroxyapatite (HA) coating on the fixation of a cementless femoral stem is discussed, in particular in cases of primary fixation with geometrically stable components. Therefore, we performed a comparative retrospective study of a series of Alloclassic-SL™ stems to: 1) present the long-term results and 2) evaluate the contribution, if any, of proximal HA coating. HypothesesLong-term cementless press-fit (“flat wedge-shaped”) fixation is reliable and HA coating only improves the radiological results of the proximal bone-prosthesis interface. Materials and MethodsOne hundred and ninety-eight Alloclassic total hip arthroplasties were performed in 179 patients, mean age 66 years old (22–85), including 105 with proximal HA coating and 93 with the original grit-blast coating. One hundred and ninety-three hips were analyzed after a mean follow-up of 9.8 years (1–24 years). ResultsResults were excellent or good in 184 hips (95%) with no significant difference between the 2 groups (Merle d’Aubigné≥16 for 89/92 (98%) without HA compared to 95/101 (94%) with HA P=0.59). Radiographic signs of stable osseointegration were observed in 173 hips (90% of the cases). HA coating significantly improved the radiographic results of the proximal bone-implant interface: (42/92 (46%) of the stems without HA had proximal radiolucencies in zones 1 and 7 compared to 4/101 (4%) with HA (P=0.0001)). Polyethylene wear>0.1 mm/year was observed in 6 hips (3%) including 1/101 (1%) in the group with HA versus 5/92 (5.4%) without HA (P=0.17). One intra-operative femoral fracture occurred and there were 9 dislocations in the first 3 postoperative months (4.5%). The main cause of revision surgery was recurrent dislocation (11/17 cases). The “revision per-100 observed-femoral component years” was 0.10 in both groups and survival for aseptic loosening of the stem was 100% (95% CI=73.2% to 100%) at 20 years. ConclusionThis study shows that secondary fixation by osseointegration of a straight standard grit-blasted titanium alloy non-anatomical implant is reliable. Possible proximal fibrous encapsulation, which is reduced by HA coating, but especially conventional polyethylene wear, were the main limitations of this system. Level of evidenceIII retrospective case-control study.

Polyethylene Wear and Osteolysis Is Associated With High Revision Rate of a Small Sized Porous Coated THA in Patients With Hip Dysplasia

The outcome of 25 primary THAs in patients with hip dysplasia using the AML Bantam femoral stem (DePuy) is reported. Age at operation averaged 43±10years. Twenty-two of 25 stems were cementless. All cementless acetabular components had conventional or cross-linked polyethylene and screws. Follow-up averaged 11±5years (range 4–18). Four cementless stems were revised after 3, 4, 8, and 9years; 2/3 cemented stems were revised at 8 and 18years. Femoral revisions demonstrated extensive conventional polyethylene wear, periprosthetic osteolysis and loosening. Five entire cups were revised for wear and loosening; four liners were replaced. Harris Hip Scores for patients with retained stems went from 43±12 to 85±13. High revision rates with the proximally porous coated Bantam stem are due to loss of fixation, often associated with polyethylene wear and osteolysis.

Comparison of Conventional Polyethylene Wear and Signs of Cup Failure in Two Similar Total Hip Designs

Multiple factors have been identified as contributing to polyethylene wear and debris generation of the acetabular lining. Polyethylene wear is the primary limiting factor in the functional behavior and consequent longevity of a total hip arthroplasty (THA). This retrospective study reviewed the clinical and radiographic data of 77 consecutive THAs comparing in vivo polyethylene wear of two similar acetabular cup liners. Minimum follow-up was 7 years (range 7–15). The incidence of measurable wear in a group of machined liners sterilized with ethylene oxide and composed of GUR 1050 stock resin was significantly higher (61%) than the compression-molded, GUR 1020, O2-free gamma irradiation sterilized group (24%) (P = 0.0004). Clinically, at a 9-year average followup, both groups had comparable HHS scores and incidence of thigh or groin pain, though the machined group had an increased incidence of osteolysis and annual linear wear rate.

Liner Exchange Into A Well Fixed Acetabular Shell In Revision Total Hip Arthroplasty

Objective To investigate clinical outcomes and complications of isolated polyethylene liner exchange for revision total hip arthroplasty.Methods From April 1995 to December 2007,80 patients (93 hips) underwent revision total hip arthroplasty during which only polyethylene liner was exchanged with reservation of acetabular cup.There were 41 males and 39 females,aged from 27 to 82 years (average,53.3 years).The duration from the primary THA to the revision surgery ranged from 0.3 to 18.4 years (average,10.9 years).The reasons for liner exchange included:polyethylene wear with osteolysis (78 hips),polyethylene wear without osteolysis (5 hips),polyethylene wear with stem loosening (4 hips),recurrent dislocation (3hips),infection (1 hip),periprosthetic fracture (1 hip) and liner dislodgement (1 hip).Forty-seven liners were fixed into the old cup using cement,and 46 were fixed with the original locking mechanism.Sixty cross-linked polyethylene liners and 33 conventional polyethylene liners were used.Results All patients were followed up for 5 to 15 years (average,7 years).The average Harris hip score improved from preoperative 86.0±16.9 to 89.4±11.6 at final follow-up.Complications included dislocation (10 hips),infection (2 hips),periprosthetic fracture (1 hip) and liner dislodgement (1 hip).Ten hips underwent rerevision due to different reasons:cup exchange (5 hips),conventional polyethylene wear (2 hips),infection (2 hips) and liner dislodgement (1 hip).Using component loosening as the end point,the 10-year survival rate was 100％ in the cement fixation group and 84.8％ in the original locking group.Using rerevision as the end point,the 10-year survival rate was 90.4％ in the cement fixation group and 65.0％ in the original locking group.Conclusion Liner exchange either with cement or original locking mechanism is a safe and successful method.Highly cross-linked polyethylene has a higher wear resistance,which can reduce incidence of osteolysis and improve survival rate of prosthesis. Key words: Arthroplasty, replacemrnt, hip; Reoperation; Polyethylene; Osteolysis

Acetabular Polyethylene Wear and Acetabular Inclination and Femoral Offset

Restoration of femoral offset and acetabular inclination may have an effect on polyethylene (PE) wear in THA. We therefore assessed the effect of femoral offset and acetabular inclination (angle) on acetabular conventional (not highly cross-linked) PE wear in uncemented THA. We prospectively followed 43 uncemented THAs for a minimum of 49 months (mean, 64 months; range, 49-88 months). Radiographs were assessed for femoral offset, acetabular inclination, and conventional PE wear. The mean (+/- standard deviation) linear wear rate in all THAs was 0.14 mm/year (+/- 0.01 mm/year) and the mean volumetric wear rate was 53.1 mm(3)/year (+/- 5.5 mm(3)/year). In THAs with an acetabular angle less than 45 degrees , the mean wear was 0.12 mm/year (+/- 0.01 mm/year) compared with 0.18 mm/year (+/- 0.02 mm/year) in those with a reconstructed acetabular angle greater than 45 degrees . Reproduction of a reconstructed femoral offset to within 5 mm of the native femoral offset was associated with a reduction in conventional PE wear (0.12 mm/year versus 0.16 mm/year). Careful placement of the acetabular component to ensure an acetabular angle less than 45 degrees in the reconstructed hip allows for reduced conventional PE wear. Level II, prospective study. See Guidelines for Authors for a complete description of levels of evidence.

Effect of counterface roughness on the wear of conventional and crosslinked ultrahigh molecular weight polyethylene studied with a multi-directional motion pin-on-disk device.

The effect of counterface roughness on the wear of conventional gamma-sterilized, and electron-beam-crosslinked ultrahigh molecular weight polyethylene was studied with a circularly translating pin-on-disk device. The counterfaces, CoCr disks, were either polished, or roughened so that they represented the type of roughening and the range of surface roughness values (R(a) = 0.014-0.24 microm) observed in explanted femoral heads of total hip prostheses. The lubricant was diluted calf serum, and the test length 3 million cycles. A total of 24 tests were done. With both types of polyethylene, there was a strong correlation between R(a) and wear factor k. The power equations were k = 5.87 x 10(-5)(R(a))(0.91) for conventional polyethylene (R(2) = 0.94), and k = 7.87 x 10(-5)(R(a))(2.49) for crosslinked polyethylene (R(2) = 0.82). Crosslinking improved wear resistance significantly. The wear of crosslinked polyethylene against the roughest counterfaces was lower than the wear of conventional polyethylene against the polished counterfaces. Against rough counterfaces, the wear of crosslinked polyethylene was an order of magnitude lower than that of conventional polyethylene. On the crosslinked polyethylene pins that were tested against polished counterfaces, remains of original machining marks were still visible after the test. The average size of wear particles produced by both types of polyethylene against rough counterfaces was similar, 0.4 microm, whereas that produced by conventional and crosslinked polyethylene against polished counterfaces was significantly smaller, 0.2 and 0.1 microm, respectively.