- Email: [email protected]
Early osteolysis with hylamer acetabular liners
The Journal of Arthroplasty Vol. 13 No. 4 1998
Brief Communication
Early Osteolysis With Hylamer Acetabular Liners James
H. Graeter,
MD, and Russell Nevins,
MD
Abstract: We reviewed 78 patients with Hylamer acetabular liners (DePuy-Dupont Orthopedics, Warsaw, IN), with a mean follow-up of 3.8 years (range, 2-6 years), for signs of osteolysis secondary to polyethylene wear. Nine patients (11.5%) showed osteolysis greater than 1 cm 2. One patient had a greater trochanter fracture through a lytic area, one patient required a revision at 4 years for severe acetabular and femoral lysis with lesser trochanter fracture, and a second patient is awaiting revision. K e y words: DePuy, Hylamer wear, osteolysis, revision.
Methods and Materials
H y l a m e r is an " e n h a n c e d " p o l y e t h y l e n e p r o d u c e d by D e P u y - D u p o n t by a process that results in longer folded p o l y e t h y l e n e chains. Initial testing f o u n d increased yield strength, modulus, a n d resistance to creep c o m p a r e d w i t h standard polyethylene. In vitro testing by McKellop et al. [1] indicated a 9 % decreased w e a r rate, a n d H y l a m e r was m a r k e t e d in 1990 as a bearing surface with i m p r o v e d w e a r resistance. However, recent reports h a v e raised the concern that H y l a m e r actually has increased w e a r rates. Griffin et al. [2] reported that at 3 years H y l a m e r liners d e m o n s t r a t e d 0.265 m m / y r of linear w e a r c o m p a r e d w i t h 0.141 m m / y r of standard polyethylene. Chmell et al. [31 published a report of five H y l a m e r liner revisions for excessive p o l y e t h y l e n e wear, but neither of these reports n o t e d osteolysis. In October 1997, Livingston et al. [4] d e m o n s t r a t e d a correlation b e t w e e n w e a r a n d early osteolysis in patients w i t h H y l a m e r liners.
F r o m 1991 until 1994, 78 patients h a d cementless p o r o u s - c o a t e d total hip arthroplasties p e r f o r m e d w i t h an acetabular Duraloc Shell and H y l a m e r liner. The average age of the patients was 64 years, the m e a n liner thickness was 8.1 m m , and the average length of follow-up was 3.8 years. Follow-up radiographs w e r e m e a s u r e d for linear p o l y e t h y l e n e w e a r as described by W a n a n d Dorr [5] and e x a m i n e d for evidence of osteolysis.
Results Nine patients (11.5 %) d e m o n s t r a t e d osteolysis -->2 cm 2 in 11 locations. Their m e a n age was 50 years and m e a n total linear H y l a m e r w e a r was 2.11 m m . Overall, the 78 patients had a m e a n H y l a m e r w e a r rate per year of 0.23 m m ; 31 patients h a d total w e a r ->1 m m in only 3.8 years of follow-up. During this same time period, 13 patients with standard polyethylene (Enduron) liners h a d only 0.11 m m / y r of w e a r a n d no osteolysis, b u t the n u m b e r of patients was not e n o u g h to m a k e statistical comparisons. The patient w h o required revision (Fig. 1) was a 50-year-old high-school principal (80 kg) w i t h severe acetabular and f e m o r a l lysis and a lesser tro-
From the George Washington University Medical Center, Washington, DC. Reprint requests: James H. Graeter, MD, 3 Washington Circle, NW, Washington, DC 20037. Copyright © 1998 by Churchill Livingstone® 0883-5403/1304-00 I453.00/0
464
Osteolysis With Hylamer
•
Graeter and Nevins
465
Fig. I. Severe osteolysis at 4 years with a Hylamer liner. (A) Large areas of femorai lysis extending into zones II and VI with lesser trochanter fracture. (B) Lateral view showing extent of involvement behind acetabular component and down femur.
chanter fracture. At the time of revision, a dense pseudocapsule was present, creating a small effective joint space, and large a m o u n t s of w e a r debris w e r e f o u n d in the f e m u r and b e h i n d the Duraloc Shell (open center hole). Both c o m p o n e n t s w e r e still well fixed, but the a c e t a b u l u m was revised a n d allograft was packed into the lyric defects of the pelvis and p r o x i m a l f e m u r (Fig. 2). A second patient
Fig. 2. Acetabular component revised; allograft struts used on femur with Dacron tape securing lesser trochanter.
is awaiting revision for groin pain, 2.5 m m of w e a r and calcar lysis.
Discussion This report supports the findings of Livingston et al. [4] that H y l a m e r liners are associated with accelerated w e a r and early osteolysis. The n u m b e r of patients (31 of 78) w i t h excessive w e a r in our series (>-I m m total wear), and the extent of the osteolysis (11.5%) at just u n d e r 4 years of followup, is s o m e w h a t alarming. The linear w e a r rate (0.23 m m / y r ) is similar to that f o u n d by Griffin et al. [2] (0.265 m m / y r ) and is significantly higher t h a n those historically reported by Charnley [6] (0.15 m m / y r ) or Livermore [7] (0.8-0.13 m m / y r ) . It is unclear w h y H y l a m e r seems to d e m o n s t r a t e the excessive w e a r rates a n d early osteolysis seen in this series. The m e t h o d of sterilization of the liners ( g a m m a irradiation in air until late in 1993) m a y h a v e decreased their resistance to wear, but as Griffin et al. [2] pointed out, this should h a v e affected the H y l a m e r and E n d u r o n p o l y e t h y l e n e equally. Presently, H y l a m e r liners are still on the m a r k e t and DePuy is conducting prospective controlled clinical trials to c o m p a r e the w e a r rates b e t w e e n H y l a m e r and Enduron. The senior a u t h o r of this c o m m u n i c a t i o n (J.H.G.) discontinued use of the H y l a m e r in 1994 primarily due to cost considerations (twice as expensive) a n d since t h e n has used
466
The Journal of Arthroplasty Vol. 13 No. 4 June 1998
o n l y E n d u r o n p o l y e t h y l e n e w i t h t h e D u r a l o c Shells. F u r t h e r f o l l o w - u p of t h e s e g r o u p s of p a t i e n t s a r e p l a n n e d , b u t i n l i g h t of t h e e a r l y w e a r a n d o s t e o l y s i s r e p o r t e d h e r e , f u r t h e r u s e of t h e H y l a m e r at this t i m e is n o t r e c o m m e n d e d .
References 1. McKellop HA: Total hip revision surgery, pp. 21-39. Raven Press, New York, 1995 2. Griffin WL, Fehring TK, McCoy TH: In vitro wear rates of enhanced polyethylene in total hip arthroplasty. Presented at the AAHKS annual meeting, Dallas, November 1996
3. Chmell MJ, Poss R, Thomas WH, Sledge CB: Early failure of Hylamer acetabular inserts due to eccentric wear. J Arthroplasty 1 h3, i996 4. Livingston B J, Chmell MJ, Spector M, Poss R: Complications of total hip arthroplasty associated with the use of an acetabular component with a Hylamer liner. J Bone Joint Surg [Am] 79:1529-i 538, 1997 5. Wan Z, Dorr LD: Natural history of femoral focal osteolysis with proximal ingrowth smooth stem implant. J Arthroplasty 11:6, 1996 6. Charnley J, Halley DK: Rate of wear in total hip replacement. Clin Orthop 112:70, 1975 7. Livermore J, Ilstrup D, Morrey B: Effect of femoral head size on wear of the polyethylene acetabular component. J Bone Joint Surg [Am] 72:518-528, I990
Brief Communication
Early Osteolysis With Hylamer Acetabular Liners James
H. Graeter,
MD, and Russell Nevins,
MD
Abstract: We reviewed 78 patients with Hylamer acetabular liners (DePuy-Dupont Orthopedics, Warsaw, IN), with a mean follow-up of 3.8 years (range, 2-6 years), for signs of osteolysis secondary to polyethylene wear. Nine patients (11.5%) showed osteolysis greater than 1 cm 2. One patient had a greater trochanter fracture through a lytic area, one patient required a revision at 4 years for severe acetabular and femoral lysis with lesser trochanter fracture, and a second patient is awaiting revision. K e y words: DePuy, Hylamer wear, osteolysis, revision.
Methods and Materials
H y l a m e r is an " e n h a n c e d " p o l y e t h y l e n e p r o d u c e d by D e P u y - D u p o n t by a process that results in longer folded p o l y e t h y l e n e chains. Initial testing f o u n d increased yield strength, modulus, a n d resistance to creep c o m p a r e d w i t h standard polyethylene. In vitro testing by McKellop et al. [1] indicated a 9 % decreased w e a r rate, a n d H y l a m e r was m a r k e t e d in 1990 as a bearing surface with i m p r o v e d w e a r resistance. However, recent reports h a v e raised the concern that H y l a m e r actually has increased w e a r rates. Griffin et al. [2] reported that at 3 years H y l a m e r liners d e m o n s t r a t e d 0.265 m m / y r of linear w e a r c o m p a r e d w i t h 0.141 m m / y r of standard polyethylene. Chmell et al. [31 published a report of five H y l a m e r liner revisions for excessive p o l y e t h y l e n e wear, but neither of these reports n o t e d osteolysis. In October 1997, Livingston et al. [4] d e m o n s t r a t e d a correlation b e t w e e n w e a r a n d early osteolysis in patients w i t h H y l a m e r liners.
F r o m 1991 until 1994, 78 patients h a d cementless p o r o u s - c o a t e d total hip arthroplasties p e r f o r m e d w i t h an acetabular Duraloc Shell and H y l a m e r liner. The average age of the patients was 64 years, the m e a n liner thickness was 8.1 m m , and the average length of follow-up was 3.8 years. Follow-up radiographs w e r e m e a s u r e d for linear p o l y e t h y l e n e w e a r as described by W a n a n d Dorr [5] and e x a m i n e d for evidence of osteolysis.
Results Nine patients (11.5 %) d e m o n s t r a t e d osteolysis -->2 cm 2 in 11 locations. Their m e a n age was 50 years and m e a n total linear H y l a m e r w e a r was 2.11 m m . Overall, the 78 patients had a m e a n H y l a m e r w e a r rate per year of 0.23 m m ; 31 patients h a d total w e a r ->1 m m in only 3.8 years of follow-up. During this same time period, 13 patients with standard polyethylene (Enduron) liners h a d only 0.11 m m / y r of w e a r a n d no osteolysis, b u t the n u m b e r of patients was not e n o u g h to m a k e statistical comparisons. The patient w h o required revision (Fig. 1) was a 50-year-old high-school principal (80 kg) w i t h severe acetabular and f e m o r a l lysis and a lesser tro-
From the George Washington University Medical Center, Washington, DC. Reprint requests: James H. Graeter, MD, 3 Washington Circle, NW, Washington, DC 20037. Copyright © 1998 by Churchill Livingstone® 0883-5403/1304-00 I453.00/0
464
Osteolysis With Hylamer
•
Graeter and Nevins
465
Fig. I. Severe osteolysis at 4 years with a Hylamer liner. (A) Large areas of femorai lysis extending into zones II and VI with lesser trochanter fracture. (B) Lateral view showing extent of involvement behind acetabular component and down femur.
chanter fracture. At the time of revision, a dense pseudocapsule was present, creating a small effective joint space, and large a m o u n t s of w e a r debris w e r e f o u n d in the f e m u r and b e h i n d the Duraloc Shell (open center hole). Both c o m p o n e n t s w e r e still well fixed, but the a c e t a b u l u m was revised a n d allograft was packed into the lyric defects of the pelvis and p r o x i m a l f e m u r (Fig. 2). A second patient
Fig. 2. Acetabular component revised; allograft struts used on femur with Dacron tape securing lesser trochanter.
is awaiting revision for groin pain, 2.5 m m of w e a r and calcar lysis.
Discussion This report supports the findings of Livingston et al. [4] that H y l a m e r liners are associated with accelerated w e a r and early osteolysis. The n u m b e r of patients (31 of 78) w i t h excessive w e a r in our series (>-I m m total wear), and the extent of the osteolysis (11.5%) at just u n d e r 4 years of followup, is s o m e w h a t alarming. The linear w e a r rate (0.23 m m / y r ) is similar to that f o u n d by Griffin et al. [2] (0.265 m m / y r ) and is significantly higher t h a n those historically reported by Charnley [6] (0.15 m m / y r ) or Livermore [7] (0.8-0.13 m m / y r ) . It is unclear w h y H y l a m e r seems to d e m o n s t r a t e the excessive w e a r rates a n d early osteolysis seen in this series. The m e t h o d of sterilization of the liners ( g a m m a irradiation in air until late in 1993) m a y h a v e decreased their resistance to wear, but as Griffin et al. [2] pointed out, this should h a v e affected the H y l a m e r and E n d u r o n p o l y e t h y l e n e equally. Presently, H y l a m e r liners are still on the m a r k e t and DePuy is conducting prospective controlled clinical trials to c o m p a r e the w e a r rates b e t w e e n H y l a m e r and Enduron. The senior a u t h o r of this c o m m u n i c a t i o n (J.H.G.) discontinued use of the H y l a m e r in 1994 primarily due to cost considerations (twice as expensive) a n d since t h e n has used
466
The Journal of Arthroplasty Vol. 13 No. 4 June 1998
o n l y E n d u r o n p o l y e t h y l e n e w i t h t h e D u r a l o c Shells. F u r t h e r f o l l o w - u p of t h e s e g r o u p s of p a t i e n t s a r e p l a n n e d , b u t i n l i g h t of t h e e a r l y w e a r a n d o s t e o l y s i s r e p o r t e d h e r e , f u r t h e r u s e of t h e H y l a m e r at this t i m e is n o t r e c o m m e n d e d .
References 1. McKellop HA: Total hip revision surgery, pp. 21-39. Raven Press, New York, 1995 2. Griffin WL, Fehring TK, McCoy TH: In vitro wear rates of enhanced polyethylene in total hip arthroplasty. Presented at the AAHKS annual meeting, Dallas, November 1996
3. Chmell MJ, Poss R, Thomas WH, Sledge CB: Early failure of Hylamer acetabular inserts due to eccentric wear. J Arthroplasty 1 h3, i996 4. Livingston B J, Chmell MJ, Spector M, Poss R: Complications of total hip arthroplasty associated with the use of an acetabular component with a Hylamer liner. J Bone Joint Surg [Am] 79:1529-i 538, 1997 5. Wan Z, Dorr LD: Natural history of femoral focal osteolysis with proximal ingrowth smooth stem implant. J Arthroplasty 11:6, 1996 6. Charnley J, Halley DK: Rate of wear in total hip replacement. Clin Orthop 112:70, 1975 7. Livermore J, Ilstrup D, Morrey B: Effect of femoral head size on wear of the polyethylene acetabular component. J Bone Joint Surg [Am] 72:518-528, I990