Catastrophic failure of the acetabular component in a ceramic-polyethylene bearing total hip arthroplasty

The Journal of Arthroplasty Vol. 13 No. 1 1998

Case Report

Catastrophic Failure of the Acetabular C o m p o n e n t in a Ceramic-Polyethylene Bearing Total Hip Arthroplasty Jordan

A. S i m o n , Steven

M D , A l a n J. D a y a n ,

A. S t u c h i n ,

MD, Enrique

Ergas, MD,

M D , a n d P a u l E. D i C e s a r e , M D

Abstract: R e c e n t r e s e a r c h in total hip a r t h r o p l a s t y h a s focused o n a t t e m p t s to decrease w e a r at t h e f e m o r a l h e a d - a c e t a b u l u m articulation, to limit t h e p r o d u c t i o n of

debris that is believed to lead to osteolysis and prosthetic loosening. The use of ceramic-on-polyethylene bearing surfaces has been reported to produce lower wear rates and therefore may increase the life expectancy of the joint arthroplasty. Problems with this bearing have been reported to be due to ceramic femoral head fracture. Reported here are 2 cases of catastrophic failure of total hip arthroplasties, involving a ceramic femoral head, caused by failure of the polyethylene acetabular liner, with subsequent penetration of the femoral head through the acetabular shell. K e y words: ceramic femoral heads, polyethylene failure, uncemented acetabular component, catastrophic wear, hip arthroplasty.

literature f r o m no w e a r at all to 0.15 m m per year [5,9,10]. A ceramic femoral h e a d offers several theoretic advantages over metallic femoral heads. Polishing of ceramic achieves a s m o o t h e r surface finish t h a n is possible in m e t a l and m a y therefore provide a lower-friction bearing surface with superior w e a r characteristics r i l l . W h e n particles of bone, cement, and m e t a l b e c o m e loose within a joint arthroplasty, the a m o u n t of d a m a g e to the femoral h e a d c o m p o n e n t is d e t e r m i n e d by its hardness. Ceramic is k n o w n to be m u c h harder t h a n metallic materials and is therefore less susceptible to third-body w e a r and scratching of its surface [4,12]. Metallic c o m p o n e n t s also experience r o u g h e n i n g of the surface finish t h r o u g h oxidation. An oxidized coating is f o r m e d on the metallic c o m p o n e n t and, with motion, is w o r n away, leading to the release of m e t a l ions. Ceramics are inert and m a i n t a i n their surface finish w i t h o u t evidence of ion release [4].

Particulate polyethylene debris f r o m total hip arthroplasty (THA) c o m p o n e n t s is believed to cause osteolysis and loosening [1,2]. Polyethylene debris m a y be released by w e a r at the femoral h e a d - u l t r a h i g h m o l e c u l a r - w e i g h t p o l y e t h y l e n e liner interface or at the liner-acetabular shell junction [3,4]. Attempts to decrease the f o r m e r source of w e a r debris h a v e led to the use of lower-friction bearing surfaces at the f e m o r a l - a c e t a b u l a r articulation. Ceramic femoral heads articulating with polyethylene acetabular liners h a v e b e e n reported to w e a r at a significantly slower rate c o m p a r e d with metallic femoral heads [5-9]. Wear rates h a v e varied in the From the Hospital for Joint Diseases, 301 East 17th Street, New York, New York. Reprint requests: Paul E. Di Cesare, MD, Hospital for Joint Diseases Orthopedic Institute, 30i East 17th Street, New York, NY 10003. Copyright © 1998 Churchill Livingstone. 0883-5403/1301-001855.00/0

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The lubrication properties of ceramics have also b e e n reported to be superior to those of metallic c o m p o n e n t s [4,12,13]. Previous reports have d o c u m e n t e d the catastrophic failure of ceramic femoral heads as a result of fracture [14,15]. To our knowledge, there have b e e n no published reports of catastrophic acetabular wear in a THA that used a ceramic-polyethylene bearing. The following are two cases of catastrophic failure of the implant bearing.

Case I The patient, a 58-year-old man, u n d e r w e n t an uncomplicated THA in 1989 for osteoarthritis using an HJD press-fit femoral stem, a 3 2 - m m Biolox alumina-ceramic femoral head, and a press-fit Optifix 5 4 - m m acetabular c o m p o n e n t with a 32-mm, 5 0 / 5 4 - m m polyethylene liner (Smith & N e p h e w Orthopaedics, Memphis, TN). After his 6 - m o n t h visit, the patient was lost to follow-up evaluation. Seven years later, the patient contacted his orthopaedic surgeon, stating that he heard squeaking noises with m o t i o n of his left hip. His range of motion, however, was painless and he remained fully ambulatory. Radiographs of his left THA showed superior migration of the femoral head within the acetabular cup, indicating significant polyethylene wear. The femoral stem appeared well fixed with no evidence of periprosthetic osteolysis. There was minimal osteolysis a r o u n d the acetabular screws,

Fig. 1. (A) Radiograph of failed left total hip arthroplasty (THA) in case 1. There is gross superior migration of the femoral head within the acetabulum, indicating severe polyethylene wear. The femoral stem remains well fixed. (B) Radiograph of failed left THA from case 2. There is superior migration of the femoral head similar to that in case 1, and osteolysis is noted in the greater trochanteric region. The stem remains well fixed distally.

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with no osteolysis n o t e d a r o u n d the periphery of the acetabular c o m p o n e n t itself (Fig. 1A). On revision surgery, a large black, fluid-filled bursa was n o t e d posterolateral to the hip joint. After removal of the femoral head, the t r u n i o n was inspected and n o t e d to be in good condition. The femoral c o m p o n e n t was not revised. After removal of the acetabular c o m p o n e n t , a large void was n o t e d in the superior aspect of the acetabulum w h e r e the ceramic femoral head had penetrated the acetabular prosthesis. The cavity and all remaining stained soft tissue were excised and the acetabulum was revised with a 5 6 - m m press-fit Reflection V acetabular shell, 2 8 - m m liner, and 2 8 - m m + 4 cobalt-chrome femoral head (Smith & N e p h e w Orthopaedics).

Case 2 The patient, a 29-year-old w o m a n , was diagnosed with seronegative juvenile r h e u m a t o i d arthritis. She u n d e r w e n t a left THA using an AML press-fit femoral stem (Depuy, Warsaw, IN), Optifix 4 6 - m m acetabular shell (Smith & N e p h e w Orthopaedics), and a 2 8 - m m ceramic femoral head with + 3 - m m neck (Depuy, Warsaw, IN) for severe hip arthritis. The patient did well until age 35, w h e n she began to experience sharp left groin pain. After approximately 18 months, she presented to her orthopaedic surgeon with worsening left groin pain. The patient had a severely limited range of motion, and there was a sense of grinding within the hip on passive

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range of motion. Radiographs revealed significant eccentric polyethylene wear with osteolysis in the greater trochanteric region. There was no radiographic evidence of femoral c o m p o n e n t loosening (Fig. 1B). The orthopaedic surgeon r e c o m m e n d e d revision surgery, but the patient refused until 4 m o n t h s later, w h e n the pain became intolerable. On revision, the hip capsule was n o t e d to be lined by blackened tissue. The acetabular c o m p o n e n t had penetrated t h r o u g h the polyethylene and metal shell (Fig. 2) and a large cyst was noted in the roof of the acetabulum. The femoral stem remained well fixed and was not revised. All blackened soft tissue was excised, the acetabular c o m p o n e n t was revised with a press-fit 52-mm acetabular shell and 2 8 - m m liner (Wright Medical, Arlington, TN), and the femoral head was replaced with a 2 8 - m m cobaltc h r o m e component.

Materials Analysis Soft tissue specimens from each patient were processed for histologic analysis. In both cases, dense fibroconnective tissue and synovium were n o t e d to contain titanium debris with histiocytic infiltrate and giant cell reaction. The retrieved components were cleaned of loose debris and visually inspected. The femoral heads were n o t e d to be dulled on the superior aspect w h e r e they articulated with the metal acetabular component. No gross chipping or cracking of the femoral heads was noted (Fig. 3A). Both ceramic femoral heads were sputter coated and e x a m i n e d with a scanning electron microscope (JSM T300, JEOL Technics, Tokyo, Japan). Photomicrographs were taken at 350 × magnification.

Fig. 2. Photograph of acetabular components retrieved in case 2. Penetration of the acetabular liner and shell is obvious. The thickness of the metal shell may also be appreciated.

Scanning electron microscopy confirmed roughening of the superior articular surface of the femoral head (Fig. 3B), whereas the inferior, nonarticular surface remained smooth (fig. 3C). An Optifix polyethylene liner thickness chart was obtained (Table 1), and the original polyethylene thickness was determined to be 3 m m in both cases. In addition to penetration of the acetabular components by the femoral head, the nonarticular surfaces of the polyethylene liners were n o t e d to have circular deformations corresponding to the screw holes in the acetabular shell (Fig. 4).

Discussion Although ceramic femoral heads have been reported to possess superior wear characteristics compared with metallic components {5-9], they are not i m m u n e to polyethylene wear. These cases illustrate the catastrophic failure of the acetabular compon e n t after 6-7 years of articulation with an a l u m i n a ceramic femoral head. In the 2 cases presented here, after penetration of the acetabular liner, the ceramic femoral head continued to erode t h r o u g h the acetabular shell, causing metallosis of the joint lining. Multiple factors were responsible for these total hip failures, including a thin polyethylene shell, nonarticular wear at the metal-polyethylene interface within the acetabular component, and the high demands of these active, relatively y o u n g patients. The Optifix acetabular cups used in both of these patients were part of a modular system w h e r e the metal thickness varies to allow the use of the same-sized polyethylene liners in different-size acetabular components. Although the acetabulum was originally sized to 54 m m in case l, the shell used had the same inner diameter as a 50-mm-o.d. component, leaving less r o o m for polyethylene. The actual polyethylene thickness was 3 ram. In case 2, the polyethylene liner was also 3 m m for the same reason (Table 1). Barrel et al. have s h o w n that the internal stresses within polyethylene with metal backing increase with decreasing polyethylene thickness, leading to polyethylene damage and the production of wear debris. Additionally, increasing n o n c o n f o r m i t y of the articulating surfaces causes a greater sensitivity to decreasing polyethylene thickness. A m i n i m u m thickness of 4 m m m a y be acceptable for virtually conforming surfaces as in a THA, although thickness must be increased as the articulation becomes less congruent [16].

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Table 1. Polyethylene Liner Thickness (ram):

Spectron EF and Opti-Fix Cups Femoral Head Sizes 22 26 28 32

Acetabular Cup Size (ram) 44-45

46-48

50-54

56-60

63-70

5 3 ---

6 4 3 --

8 6 5 3

10 8 7 5

12 10 9 7

(Data from Smith &Nephew Orthopaedics, Memphis, TN.)

Berry et al. described 10 cases of catastrophic polyethylene failure in THAs with a metal-polyethylene bearing that occurred in a patient population of 4,220 patients w h o were treated with uncem e n t e d metal-backed acetabular c o m p o n e n t s over a 7-year period. No failures were n o t e d in patients w h o s e liners were thicker t h a n 5 m m [I7]. Saikko n o t e d no evidence of wear in a 28- or 32-ram zirconia-ceramic femoral head articulating with a 10.6-mm-thick polyethylene cup in a hip simulator; however, there was significant wear w h e n a thinner 7 . 0 - m m cup was tested [9]. The rate of polyethylene wear m a y also be affected by the design of the locking m e c h a n i s m of the polyethylene liner within the acetabular shell and the conformity of the nonarticular mating surfaces [3,18[. The Optifix shell was designed with multiple screw holes, creating a significant a m o u n t of "unsupported polyethylene." Examination of the retrieved specimen in both of these cases s h o w e d gross evidence of plastic deformation in these areas (Fig. 4). N o n c o n f o r m i t y at the p o l y e t h y l e n e - m e t a l interface is believed to lead to plastic deformation and residual subsurface stresses, thus weakening the polyethylene's resistance to fatigue failure. Additionally, suboptimal locking mechanisms m a y hold the polyethylene liner proud, prohibiting intimate contact with the hemispheric shell, increasing the a m o u n t of u n s u p p o r t e d polyethylene [I8]. Microm o t i o n at the nonarticular interface has also been d o c u m e n t e d to generate wear debris that m a y be

Fig. 3. (A) Photograph of femoral heads retrieved in case 1 (top) and case 2 (bottom). The areas that appear dull (I) are the former superior, articulating surfaces. The areas that remain polished (II) are the inferior, nonarticular surfaces. (B) Scanning electron micrograph corresponding to area labeled I in Figure A. (C) Scanning electron micrograph of area labeled II in Figure A.

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Fig. 4. Photograph of the nonarticular surface of the acetabular liner retrieved in case 1. Circular impressions that are visible on this surface indicate deformation of the polyethylene in "unsupported" areas.

r e t a i n e d in u n f i l l e d s c r e w holes, c a u s i n g p e r i a c e t a b u lar o s t e o l y s i s [19,20]. It is i m p o r t a n t to l o o k for r a d i o l o g i c signs of s i g n i f i c a n t p o l y e t h y l e n e w e a r [ 2 1 - 2 3 ] in a d d i t i o n to osteolysis during follow-up examinations. A comp l a i n t of n o i s e e m a n a t i n g f r o m t h e j o i n t d u r i n g a m b u l a t i o n , e v e n w i t h o u t p a i n , m a y i n d i c a t e catas t r o p h i c p o ] y e t h y l e n e w e a r [24]. E a r l y i n t e r v e n t i o n m a y a l l o w r e p l a c e m e n t of o n l y t h e f e m o r a l h e a d a n d a c e t a b u l a r l i n e r if t h e m e t a l c o m p o n e n t s rem a i n w e l l f i x e d a n d a r e d e t e r m i n e d to be p o s i t i o n e d correctly. I n cases w h e r e t h e o r i g i n a l p o l y e t h y l e n e l i n e r w a s t h i n n e r t h a n 8 m m , t h e u s e of a s m a l l e r f e m o r a l h e a d will a l l o w a t h i c k e r p o l y e t h y l e n e l i n e r to b e i m p l a n t e d . If, h o w e v e r , significant o s t e o l y s i s is present or the femoral head has penetrated the a c e t a b u l a r liner, a m o r e e x t e n s i v e r e v i s i o n will b e n e c e s s a r y [25].

References 1. Amstutz HC, Campbell P, Kossovsky N, Clarke IC: Mechanism and clinical significance of wear debrisinduced osteolysis. Clin Orthop 276:7, 1992 2. Hamilton HW, Gorczyca J: Low friction arthroplasty at I0 to 20 years: consequences of plastic wear. Clin Orthop 318:160, 1995

3. Bono JV, Sanford L, Toussaint JT: Severe polyethylene wear in total hip arthroplasty. J Arthroplasty 9:119, 1994 4. Cuckler JM, Bearcroft J, Asgian CM: Femoral head technologies to reduce polyethylene wear in total hip arthroplasty. Clin Orthop 317:57, 1995 5. Schuller HM, Marti RK: Ten-year socket wear in 66 hip arthroplasties: ceramic versus metal heads. Acta Orthop Scand 61:240, 1990 6. Zichner LP, Willert HG: Comparison of a l u m i n a polyethylene and metal-polyethylene in clinical trials. Clin Orthop 282:86, i992 7. Derbyshire D, Fisher J, Dowson D et al: Comparative study of the wear of UHMWPE with zirconia ceramic and stainless steel femoral heads in artificial hip joints. Med Eng Phys 16:229, 1994 8. Saikko VO, Paavolainen PO, Slatis P: Wear of polyethylene acetabular cup: metallic and ceramic heads compared in a hip simulator. Acta Orthop Scand 64:391, 1993 9. Saikko ¥O: Wear of the polyethylene acetabular cup: the effect of head material, head diameter, and cup thickness studied with a hip simulator. Acta Orthop Scand 66:501, 1995 10. Sugano N, Nishi T, Nakata K et al: Polyethylene sockets and alumina ceramic heads in cemented total hip arthroplasty. J Bone Joint Surg 77B:548, 1995 11. Weightman B, Light D: The effect of the surface finish of alumina and stainless steel on the wear rate of UHMW polyethylene. Biomaterials 7:20, 1986 12. Davidson JA: Characteristics of metal and ceramic total hip bearing surfaces and their effect on longterm ultra high molecular weight polyethylene wear. Clin Orthop 294:361, 1993 13, Semlitsch M, Lehmann M, Weber H et al: New prospects for a prolonged functional lifespan of artificial hip joints by using the material combination p o l y e t h y l e n e / a l u m i n u m oxide ceramic/metal. J Biomed Mater Res 11:537, 1977 14. Otsuka NY, Schatzker J: A case of a fracture of a ceramic head in total hip arthroplasty. Arch Orthop Trauma Surg 113:8i, 1994 15. Holmer P, Nielsen PT: Fracture of ceramic femoral heads in total hip arthroplasty. J Arthroplasty 8:567, 1993 16. Barrel DL, Burstein AH, Toda MD, Edwards DL: The effect of conformity and plastic thickness on contact stresses in metal-backed plastic implants. J Biomech Eng 107:193, 1985 17. Berry D, Barnes CL, Scott RD et al: Catastrophic wear of the polyethylene liner of nncemented acetabular components. J Bone Joint Surg 76B:575, 1994 18. Rosner BI, Postak PD, Greenwald AS: Cup/liner incongruity of two piece acetabular designs: implications in the generation of polyethylene debris. Orthop Trans 18:1143, 1995 19. Chen PC, Mead EH, Pinto JG, Colwell CW: Polyethylene wear debris in modular acetabular prostheses. Clin Orthop 317:44, 1995

Catastrophic Failure of Ceramic-PolyethyleneTHA 20. Huk OL, Bansal M, Betts F et al: Polyethylene and metal debris generated by nonarticulating surfaces of modular acetabular components. J Bone Joint Surg 76B:568, 1994 2 I. Bankston AB, Ritter MA, Keating M e t ah Measurement of polyethylene thickness in total hip arthroplasty: a technique analysis. J Arthroplasty 9:533, I994 22. Devane PA, Bourne RB, Rorabeck CHet ah Measurem e n t of polyethylene wear in metal-backed acetabular cups: I. Three dimensional technique. Clin Orthop 319:303, I995

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23. Devane PA, Bourne RB, Rorabeck CH et ah Measurem e n t of polyethylene wear in metal-backed acetabular cups: II. Clinical application. Clin Orthop 319:317, 1995 24. Bono JV, Sanford L, Toussaint JT: Severe polyethylene wear in total hip arthroplasty. J Arthroplasty 9:119, 1994 25. Hozack W J, Mesa J J, Carey C, Rothman RH: Relationship between polyethylene wear, pelvic osteolysis, and clinical symptomatology in patients with cementless acetabular components. J Arthroplasty 11:769, 1996