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Total hip replacements done without cement after acetabular fractures: A 4- to 8-year follow-up study
The Journal of Arthroplasty Vol. 14 No. 7 1999
Total Hip R e p l a c e m e n t s D o n e W i t h o u t C e m e n t After A c e t a b u l a r Fractures A 4- to 8-Year Follow-up Study Michael
H. H u o , M D , * B r i a n D. S o l b e r g , MD-[- L a u r i n e
E. Z a t o r s k i , RN,:I:
a n d K r i s t a p s J. K e g g i , MD-[-:I:
Abstract: Twenty-one patients (21 hips) underwent cemenfless total hip replace-
ment surgeries for previous acetabular fractures. The mean age at the time of hip replacement was 52 years (range, 23-78 years). The mean follow-up was 65 months (range, 48-104 months). One hip required revision of the stem secondary to a periprosthetic femur fracture from a fall at 3 months after surgery. Good to excellent clinical rating was achieved and maintained in 19 hips. Radiographic evaluation demonstrated stable cup and stem fixation in 17 and 15 hips. Only 1 patient with radiographic loosening of the components was sufficiently symptomatic. The resuhs in this series appeared slightly better than those reported previously in hip replacements done with cement at comparable medium-term follow-up. The mechanical failure rates remained high in this patient population: 19% for the cups and 29% for the stems. Keywords: total hip replacement, cementless, acetabulum, fracture.
overall 14% incidence of p o s t - t r a u m a t i c arthritis of the hip in 163 acetabular fractures initially treated by open reduction surgery. Total hip r e p l a c e m e n t (THR) has been applied to treat patients with disabling pain and functional limitations after acetabular fractures. There have b e e n only a few series reported at relatively short follow-up intervals [4-7]. Romness and Lewallen [7] reported significantly increased incidence of revision and s y m p t o m a t i c and a s y m p t o m atic loosening in patients w h o had a THR for acetabular fracture than in those patients w h o u n d e r w e n t the r e p l a c e m e n t surgery fur osteoarthritis. These were especially a p p a r e n t with the cups. Limited reports [8] have b e c o m e available in the results of THR done w i t h o u t c e m e n t after acetabular fractures. The present study evaluated the clinical and radiographic results of THRs done without c e m e n t in a consecutive series of patients w h o had previous acetabular fractures. We were especially interested in the fixation durability of acetabular cups inserted without c e m e n t in acetabula that have
Acetabular fractures are serious and u n c o m m o n orthopaedic injuries. M a n y of these fractures m a y potentially result in late complications. Such complications m a y include p o s t - t r a u m a t i c arthritis, osteonecrosis of the femoral head, and chondrolysis. These complications can occur with or w i t h o u t initial surgical t r e a t m e n t . The overall incidence of degenerative changes in the hip after acetabular fractures has b e e n reported to range from 12% to 57% before the c o m m o n use of open reduction and internal fixation techniques in lrealing displaced acetabutar fractures [1,2]. Mayo [3] has reported an From the *Department of Orthopaedic Surgery, Arthritis lnstitttte, Baylor College of Medicine, Houston, Texas; i-Department of Orthopaedics and Rehabilitation, Yale Unil'ersity School eflMedicine, New Haven; and $ The Keggi Orthopaedic Foundation, Waterbury, Connecticut. No benefits or ['unds were received in support o1 I|~is study. Presented at The 6lh A n n u a l Meeting ot The American Association of Hip and Knee Surgeons. Dallas, N o v e m b e r 1996. Submilled May 6, 1997; accepted February 25, 1999. Rcprinl requests: Kristaps J. Keggi, The Keggi Orthopedic Foundation, I201 N Main SI, Waterbury, CT 06708. Copyright ¢) 1999 by Churchill Livingstone ~': 0883- 5 4 0 3 / 9 9 / 1 4 0 7 - 0 0 1 0 5 1 0 . 0 0 / 0
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been altered with previous fractures, with or without previous surgeries.
Patients and Methods The senior surgeon (K.J.K.) p e r f o r m e d 1,615 THRs f r o m J a n u a r y i985 to J a n u a r y 1993. Thirty hips (30 patients) were operated on as a result of sequelae of acetabular fractures. These represented 2% of all the hip replacements done over the study interval. Nine hips (9 patients) w e r e done for failure of a previous THR or cup arthroplasty. Therefore, there were 21 p r i m a r y THRs (21 patients) for review. There were 19 m e n and 2 w o m e n . The m e a n age at the time of hip r e p l a c e m e n t was 52 years (range, 23 to 78 years). Sixteen patients (76%) were y o u n g e r t h a n 60 years old at the time of the hip replacement. The interval b e t w e e n the initial acetabular fracture and the hip r e p l a c e m e n t was, on average, 164 m o n t h s (range, 8-480 months). The m e a n height and weight for the patients were 168 cm and 92 kg. The m e a n body mass index was 32 (range, 24-42), with 14 patients (67%) being over 30, which is considered obese. Only 2 patients were over 40, which is considered as morbid obesity. All patients except 1 were in the Charnley class A function category. The causes of the fractures included m o t o r vehicle accident (17), motorcycle accident ( i ), s n o w m o b i l e accident (1), gunshot w o u n d (1), and a fall (1). Seventeen of the patients were referred to our hospital from distant c o m m u n i t i e s for the THR surgery. An a t t e m p t was m a d e to obtain old medical records, radiographs, and c o m p u t e d t o m o g r a p h y scans from the referring physicians or hospitals to d e t e r m i n e the pattern and t r e a t m e n t of the fractures. We w e r e unsuccessful in obtaining this preoperative information in 5 patients. The patterns of the acetabular fracture in these 5 hips w e r e estimated from the most recent preoperative radiographs or classified as posterior wall fractures, especially if the patients reported an associated dislocation of the hip. The fracture patterns were assessed according to the classification system proposed by Judet and Letournel [9,10]. Fracture patterns included posterior wall (9), posterior column with associated posterior wall (5), posterior and central wall (3), T-shaped (2), and both columns (2). Posterior dislocation of the femoral head occurred in 12 hips. Surgical t r e a t m e n t was applied in 7 hips, w h e r e a s 14 hips were treated w i t h o u t surgery. Osteonecrosis of the femoral head occurred in 15 hips. Chondrolysis was a p p a r e n t in 2 hips, 1 after extensive open reduction and internal fixation and the other with-
out surgery. There was no incidence of massive osteolysis of the femoral head. Acetabular b o n e deficiency was classified according to the criteria proposed by the American A c a d e m y of Orthopaedic Surgeons [11]. Contained cavitary defects were present in 9 hips. Morcellized autograft from the resected femoral h e a d was used to fill these defects in each case. There was no case of m a j o r segmental or combined deficiencies that required structural bone grafting. All surgeries were p e r f o r m e d using a modified anterior surgical approach, which was previously described by the authors [121. No trochanteric o s t e o t o m y was used. The a c e t a b u l u m was prepared as for routine p r i m a r y THRs. H a r d w a r e from previous surgeries were not routinely removed, unless they were interfering with reaming and fitting of the cup. The f e m u r was prepared in a routine m a n n e r . All c o m p o n e n t s w e r e inserted w i t h o u t cement. Six different cup and stem designs were used over this 8-year period because of the evolving i n v e n t o r y at our hospital. Cup designs included 6 Optifix (Richards, Memphis, TN), 6 Mittehneier (Osteo, Berne, Switzerland), 3 SROM (Johnson & Johnson, Rayhem, MA), 3 Harris-Galante (Zimmer, Warsaw, IN), 2 Zweymuller (Allopro, Berne, Switzerland), and 1 SROM Supercup with m a c r o t h r e a d s (Johnson & Johnson). The surgical techniques used included u n d e r r e a m i n g by at least 1 m m in n o n threaded designs. Line-to-line reaming was done for threaded designs. Supplemental screw fixation was also used in all hemispheric n o n t h r e a d e d cups. A m i n i m u m of 2 screws were used for each cup. Stem designs included 10 Optifix, 4 Triwedge (Richards), 2 Mittelmeier, 2 Zweymuller, 2 Anatomic (Zimmer), and 1 Biofit (Richards). The Mittelmeier, Zweymuller, and Biofit designs did not have porous coating, whereas the other 3 stem designs offered proximal porous coating. Alumina ceramic femoral heads w e r e used in 19 hips. All patients were allowed to bear weight as tolerated i m m e d i a t e l y after surgery. All patients received aspirin (325 mg twice daily) for prophylaxis against t h r o m b o e m b o l i c disease. No patient received prophylaxis against heterotopic ossification. All patients w h o had a cementless THR p e r f o r m e d by the senior surgeon were followed clinically and radiographically in a prospective m a n n e r since 1983. A retrospective analysis of those patients in the present study was conducted. Clinical evaluation was by using the Harris Hip Rating Scale [6]. Radiographic evaluation of the fixation of the components was done by using criteria proposed by Callaghan et al. [13], Engh et al. [141 , Massin et al. [15], and Vresilovic et al. [16]. Stability of fixation was classified into 4 categories each for the
THRAfterAcetabular Fractures
cups and the stems: stable, possible loosening, probable loosening, and definite loosening. The evaluation criteria were based on modifications f r o m previously reported criteria for the evaluation of c e m e n t e d c o m p o n e n t s and h a v e b e e n reported by Huo et al. [17]. Femoral b o n e g e o m e t r y was assessed according to the criteria of Dorr et al. [18]. Heterotopic b o n e f o r m a t i o n was assessed according to the criteria of Brooker et al. [19].
Results The m e a n follow-up was 65 m o n t h s (range, 4 8 - 1 0 4 m o n t h s ) , with a m i n i m u m being 4 years. The m e a n surgery time was 97 m i n u t e s (range, 60-190 minutes). The m e a n estimated blood loss during surgery was 960 mL (range, 500-2200 mL). The m e a n length of hospital stay after surgery was 8 days (range, 5-13 days). Perioperative complications included 1 each of femoral calcar fracture, dislocation, sciatic n e r v e palsy, and stroke. The calcar fracture was m a n a g e d by cerclage wires and did not result in suboptimal fixation of the stem. The dislocation was successfully treated with closed reduclion, and there was no recurrence. Both patients with n e r v e palsy and stroke i m p r o v e d spontaneously over the first 6 m o n t h s after surgery, withoul residual limitations that affected their clinical ratings. One hip required revision surgery because of a femoral shaft fracture a r o u n d the stem after the patient fell at 3 m o n t h s after surgery. Revision to a longer stem w i t h o u t c e m e n t with open reduction and fixation of the fracture with cerclage wires was required, along with bone grafting. This patient did well and had an excellent clinical rating at 50 m o n t h s after revision surgery. The m e a n Harris Hip Scores were 30 (before surgery), 95 (at 2 years), and 90 (at final follow-up). There were 16 excellent results, 3 good, 1 poor, and 1 failure at the most recent follow-up. The failure was the case of femoral revision because of fracture detailed previously. The patient with a p o o r rating was experiencing significant pain resulting from probable loosening of b o t h the cup and the stem. He was cc)nsidering revision surgery at last review. Radiographic evaluation of the cups d e m o n strated the m e a n cup angle to be 41 ° (range, 30°-53°), cup height to be 23 m m (range, 11-36 ram), and cup lateralization distance to be 32 m m (range, 22-55 m m ) . The cup height, which was the vertical distance b e t w e e n the hip rotation center and the inlerteardrop line, was greater t h a n 30 m m in 4 hips, indicative of p l a c e m e n t of the cup at a higher hip rotation center. The cup lateralization distance was m e a s u r e d as the horizontal distance b e t w e e n the hip rotation center and the vertical line
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d r a w n at the medial border of the teardrop. This distance was greater t h a n 35 m m in 7 hips, indicative of p l a c e m e n t of the cup at a m o r e lateral position from ideal. These suboptimal positions of cup p l a c e m e n t reflected the a b n o r m a l a n a t o m y of the a c e t a b u l u m because of previous fractures. There was no correlation, however, b e t w e e n suboptimal p l a c e m e n t of the cups and the patterns or treatm e n t s of the acetabular fractures. Moreover, there was no correlation b e t w e e n suboptimal p l a c e m e n t of the cups and the incidence of cup loosening. Femoral b o n e g e o m e t r y before surgery was classified by the criteria of Dorr et al. [18]. There were 2 type A, 10 type B, and 9 type C femurs. The m e a n canal-fill by the stem was m e a s u r e d to be 8 8 % (proximal anteroposterior), 85% (proximal lateral), 9 6 % (distal anteroposterior), and 92% (distal lateral). Fixation status of the cups included 17 stable, 2 possible loosening, 1 probably loosening, and 1 definite loosening. All 4 loose cups were of the Mittelmeier design. One of the patients with possible loosening and the other with definite loosening were symptomatic. Fixation status of the 20 stems that r e m a i n e d in situ from the index hip r e p l a c e m e n t included 15 stable, 2 possible loosening, and 3 probable loosening. Four of the 5 loose stems were of the n o n p o r o u s designs. Both cases of possible and 1 of the probable stem loosenings were observed in patients with Dorr B femoral geometry. The other 2 cases of probable stem loosening were associated with Dorr C geometry. One of these patients (probable loosening) was symptomatic. Heterotopic ossification occurred in 6 hips: 2 grade I, 2 grade II, and 2 grade III. There was no incidence of acetabular osteolysis, but femoral osteolysis occurred in 2 hips at 87 m o n t h s and 64 m o n t h s of follow-up. The cups were stable, but the stems were probably loose in both hips. Both hips had c e r a m i c - o n - p o l y e t h y l e n e articulations, with the femoral head size being 32 m m . The femoral osteolyric defects were observed in zone 3 in 1 and zone 7 in the other.
Discussion There is increasing interest in the results of THRs after acetabular fractures. This interest has been, in part, due to n e w e r data b e c o m i n g available as well as the increased frequency of this type of reconstruction in the setting of acetabular fractures. Ronmess and Lewallen [7] reported the data of THRs after acetabular fractures done with c e m e n t from a large tertiary referral center over a 15-year time interval. Their data d e m o n s t r a t e d revision and radiographic loosening rates for the stems similar to patients w h o had u n d e r g o n e THR for osteoarthritis. In contrast,
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the revision and loosening rates for the cups were 4-fold higher t h a n those in the osteoarthritic patients. In fact, their data d e m o n s t r a t e d cup revision rate of 13.7% and loosening rate of 4 9 % with 2 7 % of those hips having s y m p t o m a t i c loosening. It has b e e n suggested by other authors that a sclerotic b o n e bed in the a c e t a b u l u m after previous acetabular fractures m a y contribute to suboptimal preparation of the a c e t a b u l u m and insufficient penetration of the cement, thus leading to early loss of stable fixation of the cups. Moreover, the failure rate was directly related to the relatively y o u n g e r age at the time of hip r e p l a c e m e n t in patients w h o have had a previous acetabular fracture. R o m n e s s and Lewallen [7] had found a difference in age b e t w e e n their patients w h o required revision surgery (42.8 years) and those w h o s e hip prostheses had rem a i n e d in situ (56.3 years). The m e a n age of our patients at the time of the acetabular fracture was 45 years, w h e r e a s the m e a n age at hip r e p l a c e m e n t was 52 years. These were slightly y o u n g e r but comparable to those in the series reported by R o m ness and Lewallen. In the present series, 75% of the patients were y o u n g e r t h a n age 60 at the time of THR. Moreover, all patients except one w e r e in Charnley class A category with only single joint i n v o l v e m e n t and no other m a j o r systemic limitations. Thus, these w e r e patients with a highd e m a n d lifestyle that would put their hip replacem e n t s at risk for accelerated failure. Karpos and Christie [8] reported the data of THRs done w i t h o u t c e m e n t in a series of 15 hips with previous acetabular fractures. The acetabular reconstructions were done with porous-coated or m e s h coated c o m p o n e n t s with s u p p l e m e n t a l screws, Morcellized b o n e - g r a f t was used in 47%, w h e r e a s structural b o n e - g r a f t was necessary in 4 0 % of the reconstructions. The m e a n follow-up was 68 m o n t h s (range, 4 8 - 1 0 0 m o n t h s ) . There was only 1 cup revision for malpositioning and recurrent dislocation. There was no case of s y m p t o m a t i c cup loosening, but 2 7 % showed radiolucencies in at least 1 acetabular zone. These data resembled those from the present study. There has been no cup revision in our series, w h e r e a s the radiographic loosening rate was 19%, with 50% of these 4 hips being s y m p t o m atic. All 4 cups with loosening in our series were of the Mittelmeier design, which was smooth, truncated, and m a c r o t h r e a d e d . There was no incidence of cup loosening a m o n g hips in which a porous hemispheric design with s u p p l e m e n t a l screw fixation was used. Our data, therefore, were similar to those reported by Karpos and Christie [8]. Our data did not d e m o n s t r a t e a n y difference of the success of cup fixation in regards to the original fracture pattern because all the fractures had healed, and
there w e r e no m a j o r structural b o n y deficiencies. Our data also did not d e m o n s t r a t e cup position to be an i m p o r t a n t factor in predicting fixation stability. We believe the m a j o r factor in the occurrence of loss of cup fixation in o u r series was related to cup design: g e o m e t r y and surface texture. There w e r e some i m p o r t a n t differences b e t w e e n our series and that of Karpos and Christie, in particular in regards to the degree of b o n e deficiency. Morcellized autograft was used to fill contained cystic defects in 4 3 % of the patients in our series, which m a t c h e d those in the Karpos series. There was no need for structural b o n e - g r a f t in a n y of our patients, w h e r e a s Karpos and Christie used structural autograft in 27% and required structural allograft in a n o t h e r 13%, indicative of m a j o r acetabular b o n e deficiencies in some of their cases. Successful results of cup fixation in our series could h a v e been partially due to less severe a n a t o m i c abnormalities of the acetabula in our patients. The success of cementless fixation of the cup r e m a i n e d high e v e n with m o r e severe b o n y deficiencies, such as reported by Karpos and Christie [81. Similar to the results observed with the cups in o u r series, 4 of the 5 loose stems were of the press-fit type w i t h o u t porous coating. The clinical rating was influenced by the suboptimal fixation of these stems. If the case of stem revision resulting from femoral shaft fracture was also included, the incidence of stable fixation in stems with porous coating was 94%. Our data thus suggest that stable fixation of b o t h the cup and the stein can be achieved and maintained at m e d i u m - t e r m follow-up using porouscoated designs in patients with previous acetabular fractures, who, in general, m a y be y o u n g e r in age and with higher activity demands. Successful l o n g - t e r m fixation of the prostheses is one of the i m p o r t a n t criteria in maintaining the clinical success of THRs. Osteolysis resulting from particulate w e a r debris, however, has b e c o m e a leading m e c h a n i s m of failure of a n y THR with or w i t h o u t c e m e n t fixation. No data w e r e reported by Romness and Lewallen [7] or by Karpos and Christie [8] in regards to the incidence of osteolysis. We observed 2 cases (9.5%) of femoral osteolysis at 87 m o n t h s and 64 m o n t h s of follow-up. The ages of the patients were 46 years and 62 years at the time of the hip replacements. The cups w e r e well fixed in both hips. The stems, however, were both loose by radiographic criteria. One of the stems was s m o o t h and the other had porous coating. The femoral heads were 32 m m in size and m a d e of alumina ceramic, which were m a t c h e d to p o l y e t h y l e n e acetabular articulating surfaces. The outer diameters of these cups of hemispherical designs were 52 m m and 58 m m . According to the specifications pro-
T H R A f t e r A c e t a b u l a r Fractures
v i d e d b y t h e m a n u f a c t u r e r s , t h e t h i c k n e s s of t h e p o l y e t h e y l e n e in t h e s e 2 cups w a s 6 m m a n d 9 m m . The relatively thin polyethylene coupled with the p r e s u m e d h i g h levels of p h y s i c a l activities in t h e s e 2 r e l a t i v e l y y o u n g p a t i e n t s c e r t a i n l y c o u l d h a v e , in part, e x p l a i n e d t h e o c c u r r e n c e of osteolysis. M o r e over, w e d i d n o t r o u t i n e l y r e m o v e t h e p r e v i o u s h a r d w a r e w h i l e p r e p a r i n g t h e a c e t a b u l u m for r e c o n s t r u c t i o n . G a l v a n i c c o r r o s i o n r e s u l t i n g f r o m dissimilar m e t a l s b e t w e e n t h e r e t a i n e d h a r d w a r e a n d t h e cup remains a potential concern that may contribu t e to t h e g e n e r a t i o n of w e a r d e b r i s a n d a s s o c i a t e d osteolysis, in p a r t i c u l a r , o n t h e a c e t a b u l a r side in t h e future. The d a t a f r o m o u r series a p p e a r e d s l i g h t l y b e t t e r t h a n t h o s e r e p o r t e d b y R o m n e s s a n d L e w a l l e n [7] at comparable follow-up intervals extrapolated from their survivorship analysis curves. Although the c e m e n t i n g t e c h n i q u e s w e r e n o t specified in t h e i r series, w e s u s p e c t t h e h i p s w e r e d o n e w i t h e a r l y cementing techniques. Our data on the cups along w i t h t h o s e r e p o r t e d b y K a r p o s a n d Christie [8] suggest that porous-coated designs with supplemental s c r e w f i x a t i o n can p r o v i d e successful m e d i u m t e r m f i x a t i o n . O u r d a t a o n t h e s t e m s suggest t h a t p r o x i m a l l y p o r o u s - c o a t e d d e s i g n s c a n offer successful f i x a l i o n as well. O n e w o u l d n o t s u s p e c t a n y d i f f e r e n t result o n t h e f e m o r a l side f r o m r o u t i n e p r i m a r y h i p r e p l a c e m e n t s d o n e for c a u s e s o t h e r than acetabular fractures because the femoral geome t r y a n d b o n e q u a l i t y w e r e n o t a b n o r m a l in t h e s e p a t i e n t s . It w o u l d h a v e b e e n i d e a l if t h e results in this series c o u l d h a v e b e e n c o m p a r e d to a series of patients without acetabular fractures who underw e n t c e m e n t l e s s THRs w i t h s i m i l a r p r o s t h e t i c d e signs. This w a s not, h o w e v e r , t h e p r i m a r y p u r p o s e of this study. F u r t h e r m o r e , s u c h c o m p a r i s o n s m a y n o t be m e a n i n g [ u l b e c a u s e of t h e s m a l l n u m b e r of cases a n d t h e v a r i e t y of p r o s t h e t i c d e s i g n s u s e d in this series. W e s u s p e c t t h e i n c i d e n c e of o s t e o l y s i s will c o n t i n u e to i n c r e a s e w i t h l o n g e r f o l l o w - u p s i m i l a r to o t h e r series of p a t i e n t s w i t h c e m e n t l e s s THRs t h a t w e h a v e f o l l o w e d . W e a r e p a r t i c u l a r l y c o n c e r n e d w i t h p a t i e n t s in this series in t h a t t h e y all received 32-mm femoral head components and t h e r e f o r e h a d t h i n n e r p o l y e t h y l e n e in t h e cups. D e t e r i o r a t i o n of b o t h clinical r a t i n g a n d f i x a t i o n stability of t h e p r o s t h e s e s is t h e r e f o r e u n a v o i d a b l e .
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2. Rowe CR, Lowell JD: Prognosis of fractures of the acetabulum. J Bone Joint Surg Am 43:30, 1961 3. Mayo KA: Open reduction and internal fixation of fractures of the acetabulum: results in 163 fractures. Clin Orthop 305:31, 1994 4. Boardman KP, Charnley J: Low-friction arthroplasty after fracture-dislocations of the hip. J Bone Joint Surg Br 60:495, 1978 5. Coventry MB: The treatment of fracture-dislocation of the hip by total hip arthroplasty. J Bone Joint Surg Am 56:1128, 1974 6. Harris WH: Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. J Bone Joint Surg Am 51:737, 1969 7. Romness DW, Lewallen DG: Total hip arthroplasty after fracture of the acetabulum: long-term results. J Bone Joint Surg Br 72:761, 1990 8. Karpos PAG, Christie M J: THR following acetabular fracture using cementless acetabular components: 4 to 8 years results. Presented at the Annual Meeting of the American Association of Hip and Knee Surgeons, Dallas, October 1995 9. Judet R, Judet J, Letournel E: Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg Am 46:1615, 1964 10. Letournel D: Acetabulum fractures: classification and management. Clin Orthop 151:81, 1980 11. D'Antonio JA, Capello WN, Borden LS, et al: Classification and management of acetabular abnormalities in total hip arthroplasty. Clin Orthop 243:126, 1989 12. Keggi KJ, Huo MH, Zatorski LE: Anterior approach to total hip replacement: surgical techniques and clinical results of our first one thousand cases using noncemented prostheses. Yale J Biol Med 66:243, 1993 13. Callaghan JJ, Dysart SH, Savory CG: The uncemented porous-coated anatomic total hip prosthesis: twoyear results of a prospective consecutive series. J Bone Joint Surg Am 70:337, 1988 14. Engh CA, Massin P, Suthers KE: Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop 257:107, 1990 15. Massin P, Schmidt L, Engh CA: Evaluation of cementless acetabutar component migration: an experimental study. J Arthroplasty 4:245, 1989 16. Vresilovic EJ, Hozack W J, Rothman RH: Radiographic assessment of cementless femoral components: correlation with intraoperative mechanical stability. J Arthroplasty 9:137, 1994 17. Huo MH, Martin RP, Zatorski LE, Keggi KJ: Total hip arthroplasty using the Zweymuller stem implanted without cement: a prospective study of consecutive patients with m i n i m u m 3-year follow-up period. J Arthroplasty 10:793, 1995 18. Dorr LD, Faugere MC, Mackel AM, et al: Structural and cellular assessment of bone quality of proximal femur. Bone 14:231, 1993 19. Brooker AF, Bowerman JW, Robinson RA, Riley LH Jr: Ectopic ossification following total hip replacement: incidence and a method of classification. J Bone Joint Surg Am 70A:337, 1988
Total Hip R e p l a c e m e n t s D o n e W i t h o u t C e m e n t After A c e t a b u l a r Fractures A 4- to 8-Year Follow-up Study Michael
H. H u o , M D , * B r i a n D. S o l b e r g , MD-[- L a u r i n e
E. Z a t o r s k i , RN,:I:
a n d K r i s t a p s J. K e g g i , MD-[-:I:
Abstract: Twenty-one patients (21 hips) underwent cemenfless total hip replace-
ment surgeries for previous acetabular fractures. The mean age at the time of hip replacement was 52 years (range, 23-78 years). The mean follow-up was 65 months (range, 48-104 months). One hip required revision of the stem secondary to a periprosthetic femur fracture from a fall at 3 months after surgery. Good to excellent clinical rating was achieved and maintained in 19 hips. Radiographic evaluation demonstrated stable cup and stem fixation in 17 and 15 hips. Only 1 patient with radiographic loosening of the components was sufficiently symptomatic. The resuhs in this series appeared slightly better than those reported previously in hip replacements done with cement at comparable medium-term follow-up. The mechanical failure rates remained high in this patient population: 19% for the cups and 29% for the stems. Keywords: total hip replacement, cementless, acetabulum, fracture.
overall 14% incidence of p o s t - t r a u m a t i c arthritis of the hip in 163 acetabular fractures initially treated by open reduction surgery. Total hip r e p l a c e m e n t (THR) has been applied to treat patients with disabling pain and functional limitations after acetabular fractures. There have b e e n only a few series reported at relatively short follow-up intervals [4-7]. Romness and Lewallen [7] reported significantly increased incidence of revision and s y m p t o m a t i c and a s y m p t o m atic loosening in patients w h o had a THR for acetabular fracture than in those patients w h o u n d e r w e n t the r e p l a c e m e n t surgery fur osteoarthritis. These were especially a p p a r e n t with the cups. Limited reports [8] have b e c o m e available in the results of THR done w i t h o u t c e m e n t after acetabular fractures. The present study evaluated the clinical and radiographic results of THRs done without c e m e n t in a consecutive series of patients w h o had previous acetabular fractures. We were especially interested in the fixation durability of acetabular cups inserted without c e m e n t in acetabula that have
Acetabular fractures are serious and u n c o m m o n orthopaedic injuries. M a n y of these fractures m a y potentially result in late complications. Such complications m a y include p o s t - t r a u m a t i c arthritis, osteonecrosis of the femoral head, and chondrolysis. These complications can occur with or w i t h o u t initial surgical t r e a t m e n t . The overall incidence of degenerative changes in the hip after acetabular fractures has b e e n reported to range from 12% to 57% before the c o m m o n use of open reduction and internal fixation techniques in lrealing displaced acetabutar fractures [1,2]. Mayo [3] has reported an From the *Department of Orthopaedic Surgery, Arthritis lnstitttte, Baylor College of Medicine, Houston, Texas; i-Department of Orthopaedics and Rehabilitation, Yale Unil'ersity School eflMedicine, New Haven; and $ The Keggi Orthopaedic Foundation, Waterbury, Connecticut. No benefits or ['unds were received in support o1 I|~is study. Presented at The 6lh A n n u a l Meeting ot The American Association of Hip and Knee Surgeons. Dallas, N o v e m b e r 1996. Submilled May 6, 1997; accepted February 25, 1999. Rcprinl requests: Kristaps J. Keggi, The Keggi Orthopedic Foundation, I201 N Main SI, Waterbury, CT 06708. Copyright ¢) 1999 by Churchill Livingstone ~': 0883- 5 4 0 3 / 9 9 / 1 4 0 7 - 0 0 1 0 5 1 0 . 0 0 / 0
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been altered with previous fractures, with or without previous surgeries.
Patients and Methods The senior surgeon (K.J.K.) p e r f o r m e d 1,615 THRs f r o m J a n u a r y i985 to J a n u a r y 1993. Thirty hips (30 patients) were operated on as a result of sequelae of acetabular fractures. These represented 2% of all the hip replacements done over the study interval. Nine hips (9 patients) w e r e done for failure of a previous THR or cup arthroplasty. Therefore, there were 21 p r i m a r y THRs (21 patients) for review. There were 19 m e n and 2 w o m e n . The m e a n age at the time of hip r e p l a c e m e n t was 52 years (range, 23 to 78 years). Sixteen patients (76%) were y o u n g e r t h a n 60 years old at the time of the hip replacement. The interval b e t w e e n the initial acetabular fracture and the hip r e p l a c e m e n t was, on average, 164 m o n t h s (range, 8-480 months). The m e a n height and weight for the patients were 168 cm and 92 kg. The m e a n body mass index was 32 (range, 24-42), with 14 patients (67%) being over 30, which is considered obese. Only 2 patients were over 40, which is considered as morbid obesity. All patients except 1 were in the Charnley class A function category. The causes of the fractures included m o t o r vehicle accident (17), motorcycle accident ( i ), s n o w m o b i l e accident (1), gunshot w o u n d (1), and a fall (1). Seventeen of the patients were referred to our hospital from distant c o m m u n i t i e s for the THR surgery. An a t t e m p t was m a d e to obtain old medical records, radiographs, and c o m p u t e d t o m o g r a p h y scans from the referring physicians or hospitals to d e t e r m i n e the pattern and t r e a t m e n t of the fractures. We w e r e unsuccessful in obtaining this preoperative information in 5 patients. The patterns of the acetabular fracture in these 5 hips w e r e estimated from the most recent preoperative radiographs or classified as posterior wall fractures, especially if the patients reported an associated dislocation of the hip. The fracture patterns were assessed according to the classification system proposed by Judet and Letournel [9,10]. Fracture patterns included posterior wall (9), posterior column with associated posterior wall (5), posterior and central wall (3), T-shaped (2), and both columns (2). Posterior dislocation of the femoral head occurred in 12 hips. Surgical t r e a t m e n t was applied in 7 hips, w h e r e a s 14 hips were treated w i t h o u t surgery. Osteonecrosis of the femoral head occurred in 15 hips. Chondrolysis was a p p a r e n t in 2 hips, 1 after extensive open reduction and internal fixation and the other with-
out surgery. There was no incidence of massive osteolysis of the femoral head. Acetabular b o n e deficiency was classified according to the criteria proposed by the American A c a d e m y of Orthopaedic Surgeons [11]. Contained cavitary defects were present in 9 hips. Morcellized autograft from the resected femoral h e a d was used to fill these defects in each case. There was no case of m a j o r segmental or combined deficiencies that required structural bone grafting. All surgeries were p e r f o r m e d using a modified anterior surgical approach, which was previously described by the authors [121. No trochanteric o s t e o t o m y was used. The a c e t a b u l u m was prepared as for routine p r i m a r y THRs. H a r d w a r e from previous surgeries were not routinely removed, unless they were interfering with reaming and fitting of the cup. The f e m u r was prepared in a routine m a n n e r . All c o m p o n e n t s w e r e inserted w i t h o u t cement. Six different cup and stem designs were used over this 8-year period because of the evolving i n v e n t o r y at our hospital. Cup designs included 6 Optifix (Richards, Memphis, TN), 6 Mittehneier (Osteo, Berne, Switzerland), 3 SROM (Johnson & Johnson, Rayhem, MA), 3 Harris-Galante (Zimmer, Warsaw, IN), 2 Zweymuller (Allopro, Berne, Switzerland), and 1 SROM Supercup with m a c r o t h r e a d s (Johnson & Johnson). The surgical techniques used included u n d e r r e a m i n g by at least 1 m m in n o n threaded designs. Line-to-line reaming was done for threaded designs. Supplemental screw fixation was also used in all hemispheric n o n t h r e a d e d cups. A m i n i m u m of 2 screws were used for each cup. Stem designs included 10 Optifix, 4 Triwedge (Richards), 2 Mittelmeier, 2 Zweymuller, 2 Anatomic (Zimmer), and 1 Biofit (Richards). The Mittelmeier, Zweymuller, and Biofit designs did not have porous coating, whereas the other 3 stem designs offered proximal porous coating. Alumina ceramic femoral heads w e r e used in 19 hips. All patients were allowed to bear weight as tolerated i m m e d i a t e l y after surgery. All patients received aspirin (325 mg twice daily) for prophylaxis against t h r o m b o e m b o l i c disease. No patient received prophylaxis against heterotopic ossification. All patients w h o had a cementless THR p e r f o r m e d by the senior surgeon were followed clinically and radiographically in a prospective m a n n e r since 1983. A retrospective analysis of those patients in the present study was conducted. Clinical evaluation was by using the Harris Hip Rating Scale [6]. Radiographic evaluation of the fixation of the components was done by using criteria proposed by Callaghan et al. [13], Engh et al. [141 , Massin et al. [15], and Vresilovic et al. [16]. Stability of fixation was classified into 4 categories each for the
THRAfterAcetabular Fractures
cups and the stems: stable, possible loosening, probable loosening, and definite loosening. The evaluation criteria were based on modifications f r o m previously reported criteria for the evaluation of c e m e n t e d c o m p o n e n t s and h a v e b e e n reported by Huo et al. [17]. Femoral b o n e g e o m e t r y was assessed according to the criteria of Dorr et al. [18]. Heterotopic b o n e f o r m a t i o n was assessed according to the criteria of Brooker et al. [19].
Results The m e a n follow-up was 65 m o n t h s (range, 4 8 - 1 0 4 m o n t h s ) , with a m i n i m u m being 4 years. The m e a n surgery time was 97 m i n u t e s (range, 60-190 minutes). The m e a n estimated blood loss during surgery was 960 mL (range, 500-2200 mL). The m e a n length of hospital stay after surgery was 8 days (range, 5-13 days). Perioperative complications included 1 each of femoral calcar fracture, dislocation, sciatic n e r v e palsy, and stroke. The calcar fracture was m a n a g e d by cerclage wires and did not result in suboptimal fixation of the stem. The dislocation was successfully treated with closed reduclion, and there was no recurrence. Both patients with n e r v e palsy and stroke i m p r o v e d spontaneously over the first 6 m o n t h s after surgery, withoul residual limitations that affected their clinical ratings. One hip required revision surgery because of a femoral shaft fracture a r o u n d the stem after the patient fell at 3 m o n t h s after surgery. Revision to a longer stem w i t h o u t c e m e n t with open reduction and fixation of the fracture with cerclage wires was required, along with bone grafting. This patient did well and had an excellent clinical rating at 50 m o n t h s after revision surgery. The m e a n Harris Hip Scores were 30 (before surgery), 95 (at 2 years), and 90 (at final follow-up). There were 16 excellent results, 3 good, 1 poor, and 1 failure at the most recent follow-up. The failure was the case of femoral revision because of fracture detailed previously. The patient with a p o o r rating was experiencing significant pain resulting from probable loosening of b o t h the cup and the stem. He was cc)nsidering revision surgery at last review. Radiographic evaluation of the cups d e m o n strated the m e a n cup angle to be 41 ° (range, 30°-53°), cup height to be 23 m m (range, 11-36 ram), and cup lateralization distance to be 32 m m (range, 22-55 m m ) . The cup height, which was the vertical distance b e t w e e n the hip rotation center and the inlerteardrop line, was greater t h a n 30 m m in 4 hips, indicative of p l a c e m e n t of the cup at a higher hip rotation center. The cup lateralization distance was m e a s u r e d as the horizontal distance b e t w e e n the hip rotation center and the vertical line
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d r a w n at the medial border of the teardrop. This distance was greater t h a n 35 m m in 7 hips, indicative of p l a c e m e n t of the cup at a m o r e lateral position from ideal. These suboptimal positions of cup p l a c e m e n t reflected the a b n o r m a l a n a t o m y of the a c e t a b u l u m because of previous fractures. There was no correlation, however, b e t w e e n suboptimal p l a c e m e n t of the cups and the patterns or treatm e n t s of the acetabular fractures. Moreover, there was no correlation b e t w e e n suboptimal p l a c e m e n t of the cups and the incidence of cup loosening. Femoral b o n e g e o m e t r y before surgery was classified by the criteria of Dorr et al. [18]. There were 2 type A, 10 type B, and 9 type C femurs. The m e a n canal-fill by the stem was m e a s u r e d to be 8 8 % (proximal anteroposterior), 85% (proximal lateral), 9 6 % (distal anteroposterior), and 92% (distal lateral). Fixation status of the cups included 17 stable, 2 possible loosening, 1 probably loosening, and 1 definite loosening. All 4 loose cups were of the Mittelmeier design. One of the patients with possible loosening and the other with definite loosening were symptomatic. Fixation status of the 20 stems that r e m a i n e d in situ from the index hip r e p l a c e m e n t included 15 stable, 2 possible loosening, and 3 probable loosening. Four of the 5 loose stems were of the n o n p o r o u s designs. Both cases of possible and 1 of the probable stem loosenings were observed in patients with Dorr B femoral geometry. The other 2 cases of probable stem loosening were associated with Dorr C geometry. One of these patients (probable loosening) was symptomatic. Heterotopic ossification occurred in 6 hips: 2 grade I, 2 grade II, and 2 grade III. There was no incidence of acetabular osteolysis, but femoral osteolysis occurred in 2 hips at 87 m o n t h s and 64 m o n t h s of follow-up. The cups were stable, but the stems were probably loose in both hips. Both hips had c e r a m i c - o n - p o l y e t h y l e n e articulations, with the femoral head size being 32 m m . The femoral osteolyric defects were observed in zone 3 in 1 and zone 7 in the other.
Discussion There is increasing interest in the results of THRs after acetabular fractures. This interest has been, in part, due to n e w e r data b e c o m i n g available as well as the increased frequency of this type of reconstruction in the setting of acetabular fractures. Ronmess and Lewallen [7] reported the data of THRs after acetabular fractures done with c e m e n t from a large tertiary referral center over a 15-year time interval. Their data d e m o n s t r a t e d revision and radiographic loosening rates for the stems similar to patients w h o had u n d e r g o n e THR for osteoarthritis. In contrast,
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the revision and loosening rates for the cups were 4-fold higher t h a n those in the osteoarthritic patients. In fact, their data d e m o n s t r a t e d cup revision rate of 13.7% and loosening rate of 4 9 % with 2 7 % of those hips having s y m p t o m a t i c loosening. It has b e e n suggested by other authors that a sclerotic b o n e bed in the a c e t a b u l u m after previous acetabular fractures m a y contribute to suboptimal preparation of the a c e t a b u l u m and insufficient penetration of the cement, thus leading to early loss of stable fixation of the cups. Moreover, the failure rate was directly related to the relatively y o u n g e r age at the time of hip r e p l a c e m e n t in patients w h o have had a previous acetabular fracture. R o m n e s s and Lewallen [7] had found a difference in age b e t w e e n their patients w h o required revision surgery (42.8 years) and those w h o s e hip prostheses had rem a i n e d in situ (56.3 years). The m e a n age of our patients at the time of the acetabular fracture was 45 years, w h e r e a s the m e a n age at hip r e p l a c e m e n t was 52 years. These were slightly y o u n g e r but comparable to those in the series reported by R o m ness and Lewallen. In the present series, 75% of the patients were y o u n g e r t h a n age 60 at the time of THR. Moreover, all patients except one w e r e in Charnley class A category with only single joint i n v o l v e m e n t and no other m a j o r systemic limitations. Thus, these w e r e patients with a highd e m a n d lifestyle that would put their hip replacem e n t s at risk for accelerated failure. Karpos and Christie [8] reported the data of THRs done w i t h o u t c e m e n t in a series of 15 hips with previous acetabular fractures. The acetabular reconstructions were done with porous-coated or m e s h coated c o m p o n e n t s with s u p p l e m e n t a l screws, Morcellized b o n e - g r a f t was used in 47%, w h e r e a s structural b o n e - g r a f t was necessary in 4 0 % of the reconstructions. The m e a n follow-up was 68 m o n t h s (range, 4 8 - 1 0 0 m o n t h s ) . There was only 1 cup revision for malpositioning and recurrent dislocation. There was no case of s y m p t o m a t i c cup loosening, but 2 7 % showed radiolucencies in at least 1 acetabular zone. These data resembled those from the present study. There has been no cup revision in our series, w h e r e a s the radiographic loosening rate was 19%, with 50% of these 4 hips being s y m p t o m atic. All 4 cups with loosening in our series were of the Mittelmeier design, which was smooth, truncated, and m a c r o t h r e a d e d . There was no incidence of cup loosening a m o n g hips in which a porous hemispheric design with s u p p l e m e n t a l screw fixation was used. Our data, therefore, were similar to those reported by Karpos and Christie [8]. Our data did not d e m o n s t r a t e a n y difference of the success of cup fixation in regards to the original fracture pattern because all the fractures had healed, and
there w e r e no m a j o r structural b o n y deficiencies. Our data also did not d e m o n s t r a t e cup position to be an i m p o r t a n t factor in predicting fixation stability. We believe the m a j o r factor in the occurrence of loss of cup fixation in o u r series was related to cup design: g e o m e t r y and surface texture. There w e r e some i m p o r t a n t differences b e t w e e n our series and that of Karpos and Christie, in particular in regards to the degree of b o n e deficiency. Morcellized autograft was used to fill contained cystic defects in 4 3 % of the patients in our series, which m a t c h e d those in the Karpos series. There was no need for structural b o n e - g r a f t in a n y of our patients, w h e r e a s Karpos and Christie used structural autograft in 27% and required structural allograft in a n o t h e r 13%, indicative of m a j o r acetabular b o n e deficiencies in some of their cases. Successful results of cup fixation in our series could h a v e been partially due to less severe a n a t o m i c abnormalities of the acetabula in our patients. The success of cementless fixation of the cup r e m a i n e d high e v e n with m o r e severe b o n y deficiencies, such as reported by Karpos and Christie [81. Similar to the results observed with the cups in o u r series, 4 of the 5 loose stems were of the press-fit type w i t h o u t porous coating. The clinical rating was influenced by the suboptimal fixation of these stems. If the case of stem revision resulting from femoral shaft fracture was also included, the incidence of stable fixation in stems with porous coating was 94%. Our data thus suggest that stable fixation of b o t h the cup and the stein can be achieved and maintained at m e d i u m - t e r m follow-up using porouscoated designs in patients with previous acetabular fractures, who, in general, m a y be y o u n g e r in age and with higher activity demands. Successful l o n g - t e r m fixation of the prostheses is one of the i m p o r t a n t criteria in maintaining the clinical success of THRs. Osteolysis resulting from particulate w e a r debris, however, has b e c o m e a leading m e c h a n i s m of failure of a n y THR with or w i t h o u t c e m e n t fixation. No data w e r e reported by Romness and Lewallen [7] or by Karpos and Christie [8] in regards to the incidence of osteolysis. We observed 2 cases (9.5%) of femoral osteolysis at 87 m o n t h s and 64 m o n t h s of follow-up. The ages of the patients were 46 years and 62 years at the time of the hip replacements. The cups w e r e well fixed in both hips. The stems, however, were both loose by radiographic criteria. One of the stems was s m o o t h and the other had porous coating. The femoral heads were 32 m m in size and m a d e of alumina ceramic, which were m a t c h e d to p o l y e t h y l e n e acetabular articulating surfaces. The outer diameters of these cups of hemispherical designs were 52 m m and 58 m m . According to the specifications pro-
T H R A f t e r A c e t a b u l a r Fractures
v i d e d b y t h e m a n u f a c t u r e r s , t h e t h i c k n e s s of t h e p o l y e t h e y l e n e in t h e s e 2 cups w a s 6 m m a n d 9 m m . The relatively thin polyethylene coupled with the p r e s u m e d h i g h levels of p h y s i c a l activities in t h e s e 2 r e l a t i v e l y y o u n g p a t i e n t s c e r t a i n l y c o u l d h a v e , in part, e x p l a i n e d t h e o c c u r r e n c e of osteolysis. M o r e over, w e d i d n o t r o u t i n e l y r e m o v e t h e p r e v i o u s h a r d w a r e w h i l e p r e p a r i n g t h e a c e t a b u l u m for r e c o n s t r u c t i o n . G a l v a n i c c o r r o s i o n r e s u l t i n g f r o m dissimilar m e t a l s b e t w e e n t h e r e t a i n e d h a r d w a r e a n d t h e cup remains a potential concern that may contribu t e to t h e g e n e r a t i o n of w e a r d e b r i s a n d a s s o c i a t e d osteolysis, in p a r t i c u l a r , o n t h e a c e t a b u l a r side in t h e future. The d a t a f r o m o u r series a p p e a r e d s l i g h t l y b e t t e r t h a n t h o s e r e p o r t e d b y R o m n e s s a n d L e w a l l e n [7] at comparable follow-up intervals extrapolated from their survivorship analysis curves. Although the c e m e n t i n g t e c h n i q u e s w e r e n o t specified in t h e i r series, w e s u s p e c t t h e h i p s w e r e d o n e w i t h e a r l y cementing techniques. Our data on the cups along w i t h t h o s e r e p o r t e d b y K a r p o s a n d Christie [8] suggest that porous-coated designs with supplemental s c r e w f i x a t i o n can p r o v i d e successful m e d i u m t e r m f i x a t i o n . O u r d a t a o n t h e s t e m s suggest t h a t p r o x i m a l l y p o r o u s - c o a t e d d e s i g n s c a n offer successful f i x a l i o n as well. O n e w o u l d n o t s u s p e c t a n y d i f f e r e n t result o n t h e f e m o r a l side f r o m r o u t i n e p r i m a r y h i p r e p l a c e m e n t s d o n e for c a u s e s o t h e r than acetabular fractures because the femoral geome t r y a n d b o n e q u a l i t y w e r e n o t a b n o r m a l in t h e s e p a t i e n t s . It w o u l d h a v e b e e n i d e a l if t h e results in this series c o u l d h a v e b e e n c o m p a r e d to a series of patients without acetabular fractures who underw e n t c e m e n t l e s s THRs w i t h s i m i l a r p r o s t h e t i c d e signs. This w a s not, h o w e v e r , t h e p r i m a r y p u r p o s e of this study. F u r t h e r m o r e , s u c h c o m p a r i s o n s m a y n o t be m e a n i n g [ u l b e c a u s e of t h e s m a l l n u m b e r of cases a n d t h e v a r i e t y of p r o s t h e t i c d e s i g n s u s e d in this series. W e s u s p e c t t h e i n c i d e n c e of o s t e o l y s i s will c o n t i n u e to i n c r e a s e w i t h l o n g e r f o l l o w - u p s i m i l a r to o t h e r series of p a t i e n t s w i t h c e m e n t l e s s THRs t h a t w e h a v e f o l l o w e d . W e a r e p a r t i c u l a r l y c o n c e r n e d w i t h p a t i e n t s in this series in t h a t t h e y all received 32-mm femoral head components and t h e r e f o r e h a d t h i n n e r p o l y e t h y l e n e in t h e cups. D e t e r i o r a t i o n of b o t h clinical r a t i n g a n d f i x a t i o n stability of t h e p r o s t h e s e s is t h e r e f o r e u n a v o i d a b l e .
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