Polyethylene liner failure in second-generation Harris-Galante acetabular components

Polyethylene liner failure of cementless acetabular components has been reported to be the most common complication of current modular cups. We performed a retrospective review of 128 consecutive primary total hip arthroplasties in 111 patients who had a second-generation Harris-Galante cup (Harris-Galante II, Zimmer, Warsaw, Ind). The mean length of the follow-up period was 8.0 years (range 5-12.9 years), with 26 cups (20.2%) having undergone revision by that time. Twenty-two hips (17.3%) had failure of the polyethylene liner. We found that polyethylene liner failure remains the main cause of revision of this modular cup. The main difference between our population of patients and other populations that have used this cup and liner is our population's cultural inclination toward squatting and leg crossing, body positions that increased the risk of impingement and eccentric wear.     

Polyethylene liner dissociation in Harris-Galante acetabular components: a report of 7 cases.

Harris-Galante modular acetabular components (Zimmer, Warsaw, IN) have been used widely for primary and revision total hip arthroplasties. The survivorship of this implant has been well documented in the literature. Failure of the liner locking mechanism and subsequent dissociation of the polyethylene liner from the metal-backed shell is a potential cause of failure, however. We report 7 cases of liner dissociation and propose the mode of failure. The result in all cases was a well-fixed metal acetabular shell with a failed locking mechanism, which usually is managed by revision of the entire component. This procedure may be accompanied by the potential loss of acetabular bone stock, which should be replenished.     

Uncemented acetabular components with polyethylene or alumina liners

Sixty consecutive patients (60 hips) were allocated in two matched-pair groups. Patients were matched for age, gender, body mass index, level of activity, and bone stock. Both groups received an uncemented total hip arthroplasty with a modular press-fit cup and an alumina femoral head. In the first group, an acetabular liner made of polyethylene was used; in the second group, an alumina liner. Both groups were followed for a minimum of 5 years. No hip required revision, and there was no radiographic evidence of aseptic loosening in either group. Mean Harris hip score was 94.7 (87.1-99) points in the polyethylene group and 93 (88.5-100) points in the alumina group.     

Late fiber metal shedding of the first and second-generation Harris Galante acetabular component. A report of 5 cases

Five patients presented with fiber metal mesh shedding of a Harris Galante II acetabular cup detected between 11 and 15 years after implantation. All patients presented with hip pain and 4 demonstrated gross acetabular loosening and fiber metal separation on preoperative radiographs. The remaining patient underwent revision surgery because of a liner dislodgment and had a radiographically well fixed shell. Loosening and fiber metal separation were detected intraoperatively. Scanning electron microscopy of the retrieved shells demonstrated isolated diffusion bonding marks in the areas where the mesh separated from the substrate and no evidence of corrosion. Progressive osteolysis in the iliac bone was evident in 4 of our cases. Progressive iliac osteolysis may lead to loss of bone support in well-fixed cups and excessive stresses transferred to the interface between the fiber metal mesh and the titanium substrate leading to the separation of the 2 layers. Fiber metal separation may contribute to long-term loosening in the Harris Galante acetabular component.     

Severe polyethylene wear in uncemented acetabular cup system components: a report of 5 cases.

We report 5 cases of severe failure of the polyethylene liner at 4 to 7.4 years after uncemented anatomic medullary locking (AML) total hip arthroplasty, using the acetabular cup system (ACS). The mode of failure was by a combination of wear-through to the metal backing and liner fracture. Four of the 5 cases were associated with a 32-mm head. The ACS design is flawed because of a lack of hemispherical geometry resulting in rim loading on a region of the liner that has the thinnest polyethylene. All patients with this type of implant should be monitored for evidence of excessive polyethylene wear.     

Revision of polyethylene acetabular liners with a cemented polyethylene cup

Various technique parameters for the revision of failed polyethylene acetabular liners using a cemented polyethylene cup were evaluated in this laboratory study. The effects of cement mantle thickness and roughening the inner surface of the shell or outer surface of the cup were determined by measuring cup dissociation strength from the metal shell after cyclic loading of the cup. The use of a cement mantle thickness of 2 to 4 mm provided dissociation strengths 3 to 4 times greater than that of the original, press-fit polyethylene liner. If a failed acetabular liner is revised by a cemented cup within the existing, well-fixed, metal shell, the size of the cup selected should create a cement mantle of <4 mm. Roughening the inside of a smooth shell or one with few screw-holes increases fixation strength approximately 20% but also creates particulate debris.     

Fixation of ultrahigh-molecular-weight polyethylene liners to metal-backed acetabular cups

Locking mechanisms and metal-liner interface surfaces of six modular acetabular systems were evaluated to determine their effect on micromotion and backside wear of the polyethylene liner. Rotational and axial motion between the metal shell and polyethylene liner was measured in the Duraloc (DePuy, Warsaw, IN), Harris-Galante (Zimmer, Warsaw, IN), Impact (Biomet, Warsaw, IN), Lip Loc (Biomet). Precision Osteoloc (Howmedica, Rutherford, NJ), and Reflection (Smith & Nephew Orthopaedics, Memphis, TN) designs at the start of each test, and at 1 million, 5 million, and 10 million cycles. At 10 million cycles, the Lip Loc and Reflection cups had significantly lower rim micromotion than the Duraloc and Harris-Galante cups (F < .0010). The Impact, Precision Osteoloc, and Reflection cups had significantly lower rim subsidence than the Harris-Galante cup (F < .0025). The Harris-Galante cup had significantly greater rotational micromotion than the Lip Loc cup (F < .0074), and had significantly greater interface slippage than the Impact and Reflection cups (F < .0070). The Lip Loc produced significantly lower dome micromotion than the Harris-Galante (F < .0300). The Lip Loc and Reflection cups had significantly less backside wear than the Duraloc and Harris-Galante cups (P < .0001), the Impact cup (P < .0243), and the Precision Osteoloc (P < .0027) cup.     

Retrieval analysis of Harris-Galante I and II acetabular liners in situ for more than 10 years

Background and purpose There have been few reports documenting the wear and oxidation performance of the polyethylene bearing surface of HGPI and HGPII THA devices. We evaluated retrieved HGPI and HGPII acetabular liners that had been in situ for more than 10 years and determined whether there was a relationship between clinical and radiographic factors, surface damage, wear, and oxidation. Materials and methods 129 HGPI and II acetabular liners with implantation times of > 10 years were retrieved at 4 institutions between 1997 and 2010. The liners were made from a single resin and were gamma radiation-sterilized in air. Surface damage, linear wear, and oxidation index (OI) were assessed. Differences in clinical and radiographic factors, surface damage, linear wear, and OI for the 2 designs were statistically evaluated separately and together. Results Articular surface damage and backside damage was similar in the 2 designs. The linear penetration rate was 0.14 (SD 0.07) mm/year for the HGPI liners and 0.12 (SD 0.08) mm/year for the HGPII liners. For both cohorts, the rim had a higher OI than the articular surface. 74% of the liners had subsurface cracking and 24% had a complete fracture through the acetabular rim. Interpretation Despite modification of the HGP locking mechanism in the HGPII design, dissociation of the liner from the acetabular shell can still occur if fracture of the rim of the liner develops due to oxidative degradation.     

Solubility changes in shelf-aged ultra-high molecular weight polyethylene acetabular liners

Crosslinking of extruded, air-packaged, irradiated, shelf-aged (10 consecutive years) polyethylene acetabular liners was measured versus time and material location by using a hot xylene extraction protocol. Insolubility (crosslinking) of new polyethylene liners was 87%, but decreased to 45% after 10 years of shelf-aging. This degradation is similar to that observed from retrieved (aged in vivo) acetabular cups. Crosslinking varied with depth in the aged liners and with radial location in the unaged liners. Given that crosslinking improves polyethylene's wear resistance, crosslinking degradation of polyethylene orthopaedic components must be controlled to improve the long-term clinical performance of total joint implants.     

Analysis and results of dissociation of the polyethylene liner in the Harris-Galante I acetabular component

The Harris-Galante I modular acetabular components (Zimmer, Warsaw, Ind) were most widely used in the 1980s in primary and revision total hip arthroplasty. We assessed 76 primary total hip arthroplasties performed using Harris-Galante I modular acetabular components. Dissociation of the polyethylene liner occurred in 5 patients and required revision surgery. None of the 76 hips had fractures of the metal locking tines on the metal shell. Liner dissociation was attributed to fatigue fracture of the polyethylene, a result of a gap between the liner and the metal shell. The thin polyethylene liner rim aggravated failure. The revision technique was to cement the polyethylene liner into the well-fixed Harris-Galante metal shell. The average follow-up observation period after revision surgery was 6.4 years; and there was no recurrence of dissociation, which supports the use of our revision technique.     

Failure of uncemented polyethylene acetabular components

The authors describe the mode of failure of the Ring UPM (Downs Brothers, Surrey, United Kingdom) uncemented metal-on-plastic total hip arthroplasty. Erosion of the external surface of the uncemented acetabular cup led to early loosening in eight cases. The subsequent production of large quantities of polylethylene debris caused massive granulomata, resulting in osteolysis of the acetabulum and femur. Revision surgery was difficult because of the loss of bone stock. The serious consequences of failure of this design lead to the conclusion that uncemented, nonmetalbacked polyethylene acetabular components should not be used.     

Wear and surface cracking in early retrieved highly cross-linked polyethylene acetabular liners

BACKGROUND: A higher degree of cross-linking has been shown to improve the tribological properties of ultra-high molecular weight polyethylene in laboratory studies; however, its effect on in vivo behavior has not been well established. We investigated in vivo wear mechanisms in retrieved highly cross-linked polyethylene acetabular liners in order to determine if early in vivo wear behavior is accurately predicted by hip-simulator studies. METHODS: A total of twenty-four liners (twenty-one explanted and one unimplanted highly cross-linked liners and two explanted ethylene-oxide-sterilized non-cross-linked liners) were examined for this study. The average age of the patients was 59.9 years, and the average time in vivo was 10.1 months. Articular surface damage on the front and back sides of the liners was assessed with an optical scoring system. Surface quadrants were assigned a grade from 0 to 3 according to the observed wear mechanisms and the percentage of surface affected. The micromechanisms of liner damage were evaluated with use of scanning electron microscopy. RESULTS: The average front and back-side explant damage scores were 11 (range, 2 to 26.5) and 6.7 (range, 3.7 to 13.3), respectively. There was consistent evidence of early surface deformation and cracking. All explants exhibited some form of surface change, including surface cracking, abrasion, pitting, or scratching. The original machining marks on the liner surface were observed to be either unaltered, drastically distorted, or absent. CONCLUSIONS: Highly cross-linked ultra-high molecular weight polyethylene acetabular liners that were retrieved at an average of ten months after implantation exhibited signs of surface damage that had not been predicted by in vitro hip-simulator studies. These devices had not failed clinically as a result of wear. The discrepancy between in vitro and in vivo wear surfaces may be due to variability in terms of in vivo lubrication and cyclic loading or may represent early surface damage mechanisms that are not well demonstrated by long-term simulator studies.     

Separation of the polyethylene liner from acetabular cup metal backing. A report of three cases.

In three young patients with cementless Porous Coated Anatomic (PCA) total hip prostheses implanted two to four years previously, the polyethylene liner separated from metal backing. These cups were of the original PCA design, manufactured and packaged as single assembled components, rather than the more recent two-piece components packaged with interchangeable liners separate from the metal backing. Each case of separation was associated with the failure of the thin outer polyethylene rim and central polyethylene peg on the back of the liner that secures it to the metal backing. Cup liners should be securely attached to the metal backing. The possibility of polyethylene failure is considerable when cementless metal-backed acetabular cups are used in active young patients.     

Late disassembly of modular acetabular components: A report of two cases

We report two cases of late disassembly of modular acetabular components, 4 and 5 years after implantation. One was revised immediately after the disassembly and one after 4 months, the latter demonstrating excessive wear of metal and polyethylene. Radiographs showing eccentric displacement of the femoral head in the cup associated with a dark, curved shadow representing the displaced polyethylene insert identify this type of implant failure.     

Revision of polyethylene acetabular liners with a cemented polyethylene cup: a laboratory study

Various technique parameters for the revision of failed polyethylene acetabular liners using a cemented polyethylene cup were evaluated in this laboratory study. The effects of cement mantle thickness and roughening the inner surface of the shell or outer surface of the cup were determined by measuring cup dissociation strength from the metal shell after cyclic loading of the cup. The use of a cement mantle thickness of 2 to 4 mm provided dissociation strengths 3 to 4 times greater than that of the original, press-fit polyethylene liner. If a failed acetabular liner is revised by a cemented cup within the existing, well-fixed, metal shell, the size of the cup selected should create a cement mantle of <4 mm. Roughening the inside of a smooth shell or one with few screw-holes increases fixation strength approximately 20% but also creates particulate debris.     

Dissociation of a metal-backed polyethylene acetabular component. A case report

A case of early failure of a total hip arthroplasty presenting as a dislocation is discussed. After failed attempts at closed reduction, an open procedure revealed that the polyethylene insert of the acetabulum had separated from its metal backing. The increasing use of metal-backed acetabular components in total hip arthroplasty produces another mechanical interface that may fail: the metal-polyethylene interface. surgeons should consider this possibility in dislocations of total hip prostheses that cannot be reduced by closed means.     

The relationship between shelf life and in vivo wear for polyethylene acetabular liners

Abstract: Although laboratory studies have correlated shelf life for gamma-irradiated-in-air polyethylene with material degradation, it is unknown whether this clinically affects wear. Therefore, we examined the relationship between shelf life and clinical wear for 152 gamma-irradiated-in-air acetabular liners. True wear rates were calculated from computer-assisted head penetration analyses of serial radiographs. Follow-up averaged 6.6 years. Shelf life averaged 11.8 months with 96% of liners having shelf lives of less than 3 years. Data analysis revealed no correlation between shelf life and true wear rates (r2 = 0.002; P = .60). This study provides useful information for surgeons concerned about shelf life as a potential cause of high wear in previously implanted components. For conventional liners in inventory less than 3 years, we found no evidence of increased wear in vivo.