Unusual cause of third-body wear in total hip arthroplasty

Harris-Galante II acetabular cup: a survival analysis

PURPOSE

To determine the survival rate of the Harris-Galante (HG) II cup and identify factors contributing to failure.

METHODS

271 primary total hip arthroplasties (THAs) performed between 1992 and 1999 in our hospitals using the HG II acetabular cup were retrospectively reviewed due to a high incidence of liner dissociation.

RESULTS

48 THAs were revised, 32 (67%) of which were due to liner dissociation. The Kaplan-Meier 10-year survival rate was 73%. Dislocation (p<0.001) and acetabular size (p=0.042) were independent predictors of acetabular component failure in the Cox's regression model.

CONCLUSION

The long-term outcome of the HG II cup is unsatisfactory. Although the HG II cup is no longer produced, numerous patients have this prosthesis in situ and should be reviewed regularly, as liner dissociation and retroacetabular osteolysis may occur.

A long-term follow-up study of the cementless THA with anatomic stem/HGPII cup with 22-mm head

The anatomic femoral component and Harris-Galante porous II (HGPII) cup were developed to provide more reliable bone ingrowth. We performed 20 cementless total hip arthroplasties (THAs) with anatomic stem/HGPII cup with 22-mm head in 14 consecutive patients, and evaluated the clinical and radiological results for a mean follow-up of 12.8 years. The all-anatomically designed stem provided excellent clinical and radiographic results. Four acetabular components underwent revision: three for fracture of the locking mechanism and wear of the polyethylene liner and one for the locking mechanism failure with dislocation of the HGPII cup. The abduction angles of the four revised acetabular components were apparently higher. The survivorship 13 years after surgery was 78%. Our findings show good long-term results using the anatomic femoral component, while the HGPII cup combined with 22-mm head seems to have poor durability due to locking mechanism failure.

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.

Third-body wear testing of a highly cross-linked acetabular liner: the effect of large femoral head size in the presence of particulate poly(methyl-methacrylate) debris

The hip simulator wear performance of an electron beam cross-linked and subsequently melted ultrahigh molecular weight polyethylene against femoral heads of 28-, 38-, and 46-mm diameter in the presence of poly(methyl-methacrylate) particulate debris was contrasted with that of conventional polyethylene against a 46-mm diameter head. Over 5 million cycles of testing, the average wear rate of the conventional polyethylene liners was 29.3 +/- 3.0 mg per million cycles. All highly cross-linked components exhibited marked reduction in wear, with the highest wear measuring 0.74 +/- 0.85 mg per million cycles. This study, using a clinically relevant third-body material, showed the electron beam cross-linked material to be far more resistant to this third-body wear than conventional ultrahigh molecular weight polyethylene, even when very large diameter femoral heads were used.

Locking mechanism failure in the Harris-Galante porous acetabular component associated with recurrent hip dislocation

In this review of longitudinal studies of the Harris-Galante porous acetabular component, 20% of all revisions were caused by failure of the polyethylene liner locking mechanism. We report 2 cases of locking mechanism failure in the Harris-Galante porous acetabular component presenting with recurrent dislocation. Broken tines from the acetabular locking mechanism were found embedded into the polyethylene liners in both cases. In a 79-year-old woman with recurrent dislocation, the polyethylene liner and femoral head were replaced, and the acetabular component was revised. In a 74-year-old man with chronic recurrent dislocation, the polyethylene liner and femoral head were replaced, but the acetabular component was preserved. Appropriate treatment for locking mechanism failure with a well-fixed acetabular component depends on many factors, and further long-term data are needed.

Dislodgment of polyethylene liners in first and second-generation Harris-Galante acetabular components. A report of eighteen cases

BACKGROUND

Dislodgment of the polyethylene liner is an increasingly common complication following total hip arthroplasty. The purposes of this study are to present the results in a series of patients with this complication and to analyze the mode of failure.

METHODS

Between November 1995 and January 2001, eighteen patients who had had a total hip arthroplasty presented with dislodgment of the polyethylene liner from a Harris-Galante metal acetabular shell. The medical records, radiographs, operative notes, and retrieved components were reviewed. In addition, scanning electron microscopy was used to study the fractured surfaces in a shell that had four broken tines.

RESULTS

The components had been in situ for an average of seven years (range, three to eleven years). Seventeen components were second generation, and one was first generation. Symptoms developed spontaneously in sixteen patients, during sexual intercourse in one, and following a fall on the hip in one. Radiographs showed eccentric positioning of the head in all of the hips and broken tines in six. All of the shells were well fixed. Treatment consisted of revision of the shell in four patients, exchange of the liner in four, cementation of a new liner into the shell in seven, and cementation of an all-polyethylene cup in three. The liners had severe damage of the rim. Scanning-electron microscopy of the fractured surfaces of four tines revealed a fatigue pattern.

CONCLUSIONS

We believe that, as the liner wears and becomes loose because of an inadequate locking mechanism, progressive micromotion occurs and the load increases on the polyethylene rim until it deforms and/or fractures. Subsequently, nothing prevents the liner from rotating out of the shell. As this mechanism of failure appears to include fatigue failure of the locking tines and wear of the liner, this complication is likely to increase as the components age in situ.

Correlation of wear debris-induced osteolysis and revision with volumetric wear-rates of polyethylene: a survey of 8 reports in the literature

This survey focused on clinical reports of polyethylene wear and osteolysis in total hip replacements. With regard to documentation of clinical wear-rates, 57 publications were reduced to an analysis of 8 reports of THR series, including the incidence of osteolysis. A direct correlation was found among volumetric wear-rates, incidence of osteolysis and revision rates in THR concepts of the 1983-1987 era. As volumetric wear rate increased, the incidence of osteolysis and revision rates increased. With regard to our grading system for volumetric wear, with follow-up in the 4-15 year range, osteolysis was rare in group A (wear = 0-80 mm3/year), ranging from 6% to 31% in group B (wear 40-80 mm3/year) and from 21% to 100% in group C (wear > 140 mm3/year). With regard to cup design, the optimal low-wear group had mainly cemented polyethylene cups with 22 and 28 mm head sizes. The mid-wear group B had metal-backed cemented and uncemented cups, with 28 mm head size, and the high-risk group C had only uncemented, metal-backed cups, with the highest wear in the 32 mm head size. Less than 10 years of follow-up did not distinguish adequately between different designs of THR, except in a few cases which had early failures due to material or design deficiencies. Overall, the cemented all-polyethylene cup combined with the smaller ball head proved to be better.

Effect of sterilization method and other modifications on the wear resistance of acetabular cups made of ultra-high molecular weight polyethylene. A hip-simulator study

BACKGROUND

Wear of ultra-high molecular weight polyethylene acetabular cups in hip prostheses produces billions of submicrometer wear particles annually that can cause osteolysis and loosening of the components. Thus, substantial improvement of the wear resistance of ultra-high molecular weight polyethylene could extend the clinical life span of total hip prostheses. It has become apparent that the conditions under which ultra-high molecular weight polyethylene cups have been sterilized can markedly affect their long-term wear properties, and new sterilization methods and other modifications have been developed to minimize the negative effects.

METHODS

In the present study, a hip-joint simulator was used to assess whether it is preferable to sterilize ultra-high molecular weight polyethylene cups without gamma irradiation, to avoid radiation-induced oxidative degradation, or to sterilize with gamma irradiation while the cups are packaged in a suitable low-oxygen atmosphere to minimize oxidation while retaining the increased wear resistance conferred by the radiation-induced cross-linking. Ion-implanted cups and cups made of a highly crystalline polyethylene (Hylamer) also were investigated. Cups made of each material were subjected to wear-testing prior to and after artificial thermal aging to accelerate oxidative degradation.

RESULTS

The results of the present study demonstrated that the cross-linking induced by gamma irradiation improves the wear resistance of ultra-high molecular weight polyethylene, while oxidation reduces it. Without thermal aging, the two types of cups that were sterilized with gamma irradiation while in low-oxygen packaging exhibited about a 50 percent lower rate of wear than did either the nonsterilized cups or the nonirradiated cups sterilized with gas plasma. There was a comparable advantage in the rate of wear after fourteen days of thermal aging. However, after thirty days of aging, the cups sterilized with gamma irradiation in low-oxygen packaging wore several times faster than did the nonirradiated cups. Ion-implanting improved the wear resistance without thermal aging, but after extensive thermal aging the oxidation and wear were greater than those of the controls. Hylamer cups (that is, those that were sterilized with gas plasma) exhibited wear properties very close to those of the nonsterilized ultra-high molecular weight polyethylene cups (the controls) with or without aging.

CONCLUSIONS

Sterilizing an ultra-high molecular weight polyethylene acetabular cup without radiation (for example, with ethylene oxide or gas plasma) avoids immediate and long-term oxidative degradation of the implant but does not improve the inherent wear resistance of the polyethylene. Sterilizing with use of gamma irradiation with the implant packaged in a low-oxygen atmosphere avoids immediate oxidation and cross-links the polyethylene, thereby increasing its wear resistance, but long-term oxidation of the residual free radicals may markedly reduce the wear resistance. Ideally, cross-linking with gamma irradiation to reduce wear should be done in a manner that avoids both immediate and long-term oxidation.

Wear of gamma-crosslinked polyethylene acetabular cups against roughened femoral balls

Crosslinking of ultrahigh molecular weight polyethylene has been shown to markedly improve its wear resistance in clinical studies and laboratory tests using hip joint simulators. However, because most of the laboratory studies have been done under clean conditions using prosthesis-quality, highly polished counterfaces, there is concern regarding how well an intentionally crosslinked polyethylene acetabular cup will resist abrasion by a femoral ball that has been damaged by third-body abrasion in vivo. To investigate this, conventional and radiation crosslinked-remelted acetabular cups of ultra-high molecular weight polyethylene were tested in a hip joint simulator bearing against smooth femoral balls and against balls with moderate and severe roughening. Cups were tested with and without aging to accelerate any oxidative degradation. The crosslinked cups were produced by exposing extruded GUR 4150 bar stock of ultrahigh molecular weight polyethylene to 5 Mrad gamma radiation under a partial vacuum and then the bars were remelted to extinguish residual free radicals. Artificial aging at 70 degrees C under 5 atm oxygen for 14 days induced negligible oxidation in the crosslinked and remelted material. Against smooth balls, the wear of the crosslinked cups, with or without aging, averaged approximately 15% of that of the conventional cups. Against the moderately rough balls, the wear rate of the conventional cups was unchanged, whereas the wear rate increased slightly for the nonaged and aged crosslinked cups, but was still only 26% and 20% of that of the conventional cups, respectively. Against extremely rough balls, the mean wear rates increased markedly for each material such that during the final 1 million cycle interval, the average wear rates of the nonaged and the aged crosslinked cups were 72% and 47% of that of the conventional cups, respectively. That is, the crosslinked polyethylene showed substantially better wear resistance than conventional polyethylene across the range of ball roughnesses, with or without accelerated aging.