Femoral Components:
Cemented Stems for Everybody?
Ove Furnes, Leif Ivar Havelin and Birgitte Espehaug
Summary
There is considerable evidence from our register studies, that cemented implants both in femur and acetabulum give satisfactory long-term (15 years) results. These find- ings apply both for young and old patients, and for all diagnostic groups. Cemented polished tapered stems have been reported with good results both in the Norwegian and Swedish hip implant registers. The Exeter and Charn- ley total hip implants (cup and stem) had similar results after 15 years follow up.
Introduction
During the 1980s, the use of uncemented femoral stems in total hip arthroplasty (THA) gained popularity, but still many surgeons regard the cemented metal stem with a small head articulating with a cemented all polyethylene acetabular socket as the gold standard for hip replace- ments. The Norwegian Arthroplasty Register started reg- istration of hip implants in 1987 as a prospective ongoing study. The unique identification number given to each inhabitant of Norway enabled us to follow implants in many patients for extended periods of time. In several studies we have focused on the survival of different types of cemented and uncemented hip prostheses used in Nor- way [5]. In this paper we will present the latest update on femoral stem prostheses with up to 15 years of follow up.
Results of Cemented and Uncemented Stems
Our results indicated that both cemented and unce- mented stems do well both in young and old patients
(
⊡Figs. 8.1 and 8.2). Uncemented stems had marginally better results than the cemented stems in young patients (<60 years) [3], when the smooth pressfit Biofit stem was excluded (
⊡Fig. 8.3). The uncemented stem with the best result in Norway was the HA coated Corail stem with a 15 year survival of 95.1%. In patients younger than 60 years, the Corail stem had a 12-year survival of 96.2%.
For several uncemented stems concern has been raised due to increased incidence of thigh pain documented. In one randomised study the uncemented implant gave 17%
thigh pain and the cemented implant 3% [8]. There is also concern as to what will happen when the hydroxyl- apatite disappears, will there subsequent be more aseptic loosening?
The cemented stems are well documented both regarding the survival of the implant and for pain relief [1]. The polished tapered Exeter stem had the best results of the cemented stems with a 15 year survival of 97.0%. In patients younger than 60 years, the Exeter stem had a 12 year survival of 95.2%. There were differences in results among the cemented stems. The polished tapered Exeter stem had better survival than the straight vaquashined Charnley stem (
⊡Fig. 8.2,
⊡Table 8.1). These results com- pared well with the results of the Exeter implant in the Swedish Hip Register [9].
Results of THA System (Cup and Stem Combined)
However, it is arbitrary to look at only one of the compo-
nents, as the results may change when we study the whole
prosthetic system (cup and stem). Both in all patients
and in patients younger than 60 years the result of the
whole prosthesis was similar for Exeter and Charnley
implants (
⊡Fig. 8.4). The reason was less revisions of the
⊡ Fig. 8.1a,b. Cox-adjusted survival curves for cemented (Palacos or Simplex) and uncemented stem brands in all age groups. Adjusted for age, gender and diagnosis. a Cemented stems, endpoint revision of
stem. b Uncemented stems, endpoint revision of stem. (The Norwegi- an Arthroplasty Register 1987–2004)
Cemented and uncemented stems, 10 most common prostheses
0 4 8 12 16 50
60 70 80 90 100
CHARNLEY EXETER TITAN SPECTRON ITHLUBINUS SP BIO-FIT ELITE CPTMS-30
50 60 70 80 90 100
CORAIL FILLER PROFILE ZWEYMÜLLER LMTSCP
ABG I OMNIFIT TI-FIT BIO-FIT
a b
0 4 8 12 16
⊡ Fig. 8.2a,b. Cox-adjusted survival curves for cemented (Palacos or Simplex) and uncemented stem brands in patients younger than 60 years of age. Adjusted for age, gender and diagnosis. a Cemented
stems, endpoint revision of stem. b Uncemented stems, endpoint revi- sion of stem. (The Norwegian Arthroplasty Register 1987–2004) 0 4 8 12 16
50 60 70 80 90 100
CHARNLEY EXETER SPECTRON TITAN ITH MS-30 ELITE LUBINUS SP CPT C-STEM
N 2198 614 441 275 239 144130 95 91
66 50
60 70 80 90 100
CORAIL PROFILE SCP FILLER ZWEYMÜLLER OMNIFIT ABGTI-FIT BIO-FIT LMT
N 3639 754388 381 327 245 240200 181 144 Cemented and uncemented stems in patients <60 years
a b
0 4 8 12 16
8
⊡ Fig. 8.4a,b. Cox-adjusted survival curves for cemented (Palacos or Simplex) and uncemented primary total hip arthroplasty (cup and stem) brands in patients younger than 60 years of age. Adjusted for
age, gender and diagnosis. a Cemented arthroplasties, endpoint any revision. b Uncemented arthroplasties, endpoint any revision. (The Norwegian Arthroplasty Register 1987–2004)
Cemented and uncemented cup/stem combinations, age < 60, 10 most common prostheses
0 4 8 12 16 50
60 70 80 90 100
CHARNLEY/CHARNLEY EXETER/EXETER REFLECTION/SPECTRON SPECTRON/ITH ALLO PRO/MS-30 TITAN/TITAN KRONOS/TITAN ZCA/CPT CHARNLEY/ELITE LUBINUS SP/LUBINUS SP
0 5 10 15 50
60 70 80 90 100
TROPICAL/CORAIL ATOLL/CORAIL IGLOO/FILLER GEMINI/PROFILE TRILOGY/TROPIC DURALOC/PROFILE DURALOC/SCP ENDLER/ZWEYMÜLLER REFLECTION/TROPIC TI-FIT/BIO-FIT
a b
⊡ Fig. 8.3a,b. Cox-adjusted survival curves for prostheses commonly used in patients younger than 60 years of age. Adjusted for age, gen- der and diagnosis. a Cemented and uncemented cup/stem, revision
of cup. b Cemented and uncemented cup/stem, revision of stem. (The Norwegian Arthroplasty Register 1987–2004)
Cemented and uncemented cup/stem combinations, age < 60, 10 most common prostheses
0 4 8 12 16 50
60 70 80 90 100
CEMENTED (Palacos or Simplex) UNCEMENTED (Ti-fit/Bio-fit excluded)
0 4 8 12 16 50
60 70 80 90 100
CEMENTED (Palacos or Simplex) UNCEMENTED (Ti-fit/Bio-fit excluded)
a b
Charnley acetabular components. This was probably due to the smaller head (22,2 mm) in the Charnley implant compared to the Exeter implant (28 mm and 30 mm). The smaller heads give less wear and subsequently less aseptic loosening of the acetabular component [10].
The uncemented implants had worse results than the cemented implants because of more aseptic loosening and polyethylene wear in press-fit HA coated cups, and polyethylene wear and osteolysis in press-fit hemispheric porous coated cups
⊡Fig. 8.4[3, 6, 7].
The titanium stem prostheses (Titan and ITH) used in Norway had good 15 years results, with a 93.2% and 95.1% survival of the stem (
⊡Fig. 8.2). These prostheses were mainly used in patients over 60 years of age.
The cemented anatomic Lubinus SP stem had good results in the Swedish register [5], but in the Norwegian register the Lubinus SP stem had a survival of 91.7% after 15 years (
⊡Table 8.1). The results from Norway with the Lubinus SP stem were mainly based on operations from two hospitals, and the inferior results were from one hospital. The results must therefore be interpreted with caution.
Why Were Results Worse in Young Patients?
In a study of the influence of the hip diagnosis we used cemented Charnley prostheses as a control group [4]. We found that the reason for poor prognosis in some hip diseases in young patients were due to the fact that these young patients had been given a poorly performing uncemented hip implant. These implants were introduced as more promising than the established cemented implants during the 1980s. During the last 15 years these implants have failed in large numbers. The reason for failures were aseptic loosening of uncement- ed smooth press-fit stems, threaded cups with smooth
surface, or porous coated stems without circumferen- tial coating. If the patient had been given a cemented Charnley prosthesis using a well-documented cement (Palacos or Simplex), the survival of the implant was good both in young and old patients in all hip-diagnosis groups [4].
There is considerable evidence from our register stud- ies that cemented implants both in femur and acetabulum give good long-term results in all age groups. At our institution, we use cemented implants (both in femur and acetabulum) with a small head (22 mm) in young patients. In older patients (>80 years) where the poly- ethylene wear problem is negligible and the dislocation problem is greater, we use femoral heads of 32 mm [2].
Take Home Messages
I I
▬
Implant survival should not only be judged by evaluation of stem or cup in isolation, but assessed as a THA system.▬
Cemented THA performs equally well in all age groups compared to the best uncemented sys- tems.▬
Uncemented acetabular components pose the increased risk of wear and osteolysis (and aseptic loosening).▬
Cemented THA remains the gold standard also for the young patient until better outcome has been documented for new uncemented designs.Acknowledgements. We thank orthopaedic surgeons at all hospitals in Norway, without whose co-operation the Norwegian Arthroplasty Register would not be possible.
The work of the register is a teamwork and we thank our co-authors Lars B. Engesæter, Stein Emil Vollset and Stein Atle and our secretaries Adriana Opazo, Inger Skar and Ingunn Vindenes for their accurate registration.
⊡ Table 8.1. The 10 most commonly used cemented stems used in Norway. The revision percentage were calculated by Cox regression adjusting for age, gender and diagnosis and cement (Palacos, Simplex). The Norwegian Arthroplasty Register 1987–2004
Stem Prostheses N R Median Follow-up in Years Revision % at 10 Years Revision % at 15 Years
Charnley 26221 976 5.8 5.5 (5.0–5.9) 7.9 (7.1–8.7)
Exeter 7567 138 5.7 2.2 (1.7–2.7) 3.0 (2.3–3.8)
Titan 7439 118 5.1 2.4 (1.9–3.0) 6.8 (4.6–8.9)
Spectron 3889 17 1.6 * *
ITH 3533 64 7.2 2.1 (1.5–2.7) 4.9 (2.6–7.2)
Lubinus SP 1657 62 5.8 4.5 (3.1–5.9) 8.3 (5.2–11.3)
Bio-Fit 1556 10 6.8 1.0 (0.3–1.6) *
CPT 875 6 2.8 * *
Elite 829 24 3.4 7.9 (3.9–12) *
MS-30 816 7 2.4 * *
*Insufficient follow-up
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