- Email: [email protected]
Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy
Journal of Orthopaedic Science xxx (2017) 1e6
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy Koji Goto a, b, *, Yuki Furuya b, Kazuhiro Oda b, Ryosuke Minami b, Kaori Sano b, Masayuki Sugimoto b, Shuichi Matsuda a a b
Department of Orthopaedic Surgery, Kyoto University, Kyoto, Japan Department of Orthopaedic Surgery, Nagahama City Hospital, Shiga, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 15 July 2017 Received in revised form 23 November 2017 Accepted 6 December 2017 Available online xxx
Background: The Elite-Plus stem has two shape variations: roundback and flanged. The correlation between the radiographic results and stem geometry has not been previously investigated. The objective of this study was to evaluate the long-term primary total hip arthroplasty results using Elite-Plus stems, and the effect of stem geometry on radiographic distal femoral cortical hypertrophy. Methods: We retrospectively evaluated, radiographically, 156 patients (173 hips) who underwent total hip arthroplasty between April 1998 and November 2005, and were followed up for >5 years, postoperatively. Radiographic factors affecting distal femoral cortical hypertrophy were analysed using multivariable logistic regression analysis. Results: The mean follow-up period was 11.6 (5e17.8) years. During follow-up, femoral components were revised in 7 hips; one was revised due to aseptic loosening. Another femoral component was loosened and waiting for revision. The 10- and 15-year survival rates for aseptic stem loosening were 100% and 98.1% (95% CI: 92.5e99.5), respectively. Distal femoral cortical hypertrophy occurred in 23 hips (14.8%), and more often with roundback type (34.1%) than with flanged type (7.2%). Distal femoral cortical hypertrophy was observed in 34.8% of hips with valgus alignment, 11.3% with neutral alignment, and 12.5% with varus alignment. Multivariable logistic regression analysis showed that roundback stem shape and valgus stem alignment significantly affected the occurrence of distal femoral cortical hypertrophy. Conclusions: The Elite-Plus stem has excellent long-term clinical and radiographic results in Japanese patients. The occurrence of distal femoral cortical hypertrophy significantly depends on the shape and alignment of Elite-Plus stems. © 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
1. Introduction The Charnley Elite-Plus stem (Depuy, Warsaw, IN, USA) was developed as the successor model to the original Charnley stem and became commercially available in 1994. This stem has had mixed clinical results [1e7]. Walton et al. reported that 16.4% (26 of 159) of Elite-Plus stems had either been revised or had definite evidence of radiological loosening of the component at a mean of 6.4 years,
* Corresponding author. Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Shogoin, Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan. Fax: þ81 75 751 8409. E-mail address: [email protected] (K. Goto).
postoperatively [4]; however, Kim et al. reported that the stem survival rate at 12 years was 99% [2]. The Elite-Plus stem is characterised by its specific flanged shape, and has two shape variations according to its size: roundback type for congenital dislocation of the hip (CDH) and stem size 1, flanged type for stems larger than size 3, and both types for size 2 (Fig. 1a). The shape variations cannot be distinguished in plain radiographs (Fig. 1b). Although the stem's shape has a significant effect on bone cement pressurisation and thus the long-term radiographic results, no long-term results have been reported with reference to the different shapes of the Elite-Plus stem [8]. On the other hand, distal femoral cortical hypertrophy (DFCH), the typical radiographic appearance of which is shown in Fig. 1b, is
https://doi.org/10.1016/j.jos.2017.12.003 0949-2658/© 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
2
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
2. Materials and methods 2.1. Patient demographics The study protocol was approved by the institutional review board of our hospital. Between April 1998 and November 2005, 199 consecutive primary THAs (in 182 patients) were performed using a cemented Elite-Plus femoral stem (Depuy, Warsaw, IN, USA). Of the 182 patients, 19 were lost to follow-up, and 7 patients died from unrelated causes within 5 years postoperatively. Thus, we retrospectively reviewed data on 173 hips (in 156 patients) with a postoperative follow-up of more than 5 years (follow-up rate: 90.1%). Among them, 18 hips (in 18 patients) were excluded from radiographic evaluation, because 16 had no radiographs available at the final follow-up because the patient died or moved to another region, and 2 hips were infected within 5 years. We telephoned the 16 patients or their families and asked them about their condition and whether revision surgeries had been performed. We performed radiographic evaluation for 155 hips (Fig. 2). 2.2. Surgical procedure and rehabilitation programme THA was performed through direct lateral approaches, including a Charnley transtrochanteric approach in 30 (17.3%), Dall's approach in 141 (81.5%), and a Hardinge approach in 2 (1.2%). Cemented acetabular components were used in all hips, including LPW (DePuy) in 7 (4.0%), FPW (DePuy) in 118 (68.2%), Offset bore (DePuy) in 1 (0.6%), Ogee (DePuy) in 46 (26.6%), and unknown in 1 (0.6%). All acetabular components were made of conventional polyethylene. For the femoral prostheses, an Elite-Plus stem (DePuy) and an Orthron modular head (22.225 mm in diameter) (DePuy) were used in all cases. Both acetabular and femoral components were fixed with the third-generation cementing technique, and the cement used was CMW1 (DePuy) in 14 (9.0%) cases, Endurance (DePuy) in 131 (84.5%), and both cements in 10 (6.5%). Postoperative gait exercise with partial weight bearing started 2e4 weeks after surgery, and full weight bearing was allowed 4e8 weeks after surgery. 2.3. Clinical and radiographic evaluation Hip function was evaluated using the Japanese Orthopaedic Association (JOA) score [16], which is based on pain (40%), range of movement (20%), ability to walk (20%), and activities of daily living (20%). The total score is 100 points for a normal hip. We evaluated radiographs for 155 hips for which annual standard anteroposterior
Fig. 1. (a) Two shape variations of the Elite Plus stem: right side, roundback type; left side, flanged type. The flange curved medially in the distal portion, which is different from the design of the original Charnley stem. (b) A postoperative AP radiograph of a 69-year-old female: right hip (flanged type-stem) at 12 years postoperatively, left hip (roundback type-stem) at 13 years postoperatively. Arrows indicate DFCH.
commonly considered to be caused by stress overload around the femoral stem tip, and many have reported the relevance between clinical outcomes or radiographic factors and DFCH [9e15]. However, DFCH around the Elite-Plus stem with the two shape variances has not been reported. In this retrospective study, we evaluated the long-term clinical and radiographic results of primary total hip arthroplasty (THA) using the Elite-Plus stem, and examined the correlation between the stem geometry and radiographic results.
Fig. 2. Follow-up flowchart of the patients.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
(AP) radiographs were available. Two of the authors who were not involved in the initial surgeries performed the radiographic evaluations. The authors discussed the radiographic parameters and determined them through consensus. The radiolucent line (RL) was evaluated in all zones around the socket as described by DeLee and Charnley [17], while RL and osteolysis (OL) around the femoral prosthesis, as described by Gruen et al. [18]. Stem alignment was evaluated on the postoperative AP radiographs, and valgus or varus alignment less than 2 was categorised as neutral. Radiographic loosening was assessed according to the criteria of Hodgkinson et al. for acetabular components [19] and the criteria of Harris et al. for femoral prostheses [20]; radiographic loosening was confirmed when complete demarcation or implant migration was detected. DFCH were evaluated according to the modified Gruen zones described by Fujita et al. [21]. Kappa coefficients for interobserver variability of radiographic loosening, OL, and DFCH were 1, 0.66, and 0.86, respectively. 2.4. Statistical analysis KaplaneMeier survival analysis was used to evaluate the time to implant loosening seen on radiographs, revision surgery for any reason, and revision surgery for aseptic loosening for both acetabular and femoral components. The log-rank test was used to evaluate the relationships between aseptic stem loosening-free survival and stem shape. Patients' demographic data and radiographic results for roundback and flanged type were compared using unpaired T-test or chi-square test. We also analysed possible factors associated with DFCH, which included age, body weight, body mass index (BMI), follow-up period, stem shape, stem size, stem alignment, RL around the stem, and OL around the stem, using univariable and multivariable logistic regression analyses. To analyse the effect of the size of the femoral component, CDH, size 1, and size 2 were consolidated and designated as small stem, while size 3 and 4 as large stem. All statistical analyses were performed with JMP IN version 10.0.2 (SAS Institute Inc., Cary, NC, USA) or Excel Statistics 2015 for Windows (Social Survey Research Information Co., Ltd., Tokyo, Japan). Two-sided p-values < 0.05 were considered significant. 3. Results 3.1. Patient demographics Of the 156 patients, 16 were men (17 hips) and 140 were women (156 hips) with a mean age at the time of surgery of 63.8 years (range, 42e84). Mean body weight and body mass index (BMI) for the men and women were 52.4 kg (range, 32e78 kg) and 23.3 kg/
3
m2 (range, 15.0e32.1 kg/m2), respectively. The diagnosis was osteoarthritis in 157 hips (90.8%), rheumatoid arthritis in 11 (6.4%), osteonecrosis of the femoral head in 3 (1.7%), and rapidly destructive osteoarthritis in 2 (1.2%) (Table 1). There were significant differences on the height and follow-up period between roundback and flanged type (Table 1). Although the perioperative radiographs were not available for all patients, serial radiographs taken during postoperative follow-up predicted that the cementation of all the prostheses would be graded A or B, according to the criteria of Barrack et al. [22]. 3.2. Surgical results The mean follow-up period was 11.6 years (range, 5e17.8). The mean JOA score improved significantly from 44.8 (range, 13e82) preoperatively to 86.4 (range, 59e100) at the final follow-up. Of the 173 THAs, 10 hips required revision during the follow-up period. Sockets were revised in 10 hips, and femoral components were revised in 7 hips. Sockets were revised due to aseptic loosening in 4 hips, infection in 3, wear and osteolysis in 2, and recurrent dislocation in 1. Femoral component revision was performed due to aseptic loosening in 1 hip, infection in 3, and implant mismatch or for optimal exposure of the acetabulum during the socket revision procedure in 3. In another 6 cases, radiographic loosening of either the acetabular component (5 cases) or the femoral component (1 case) was confirmed during the follow-up period. The former cases did not undergo revision, because the patients had no symptoms around the hip, and the latter case was waiting for revision. Roundback type stems were used in both cases of femoral aseptic loosening. 3.3. Survival rates The KaplaneMeier survivorship analysis with implant revision for any reason as the endpoint showed a survival rate of 95.0% (95% CI: 90.2e97.5) at 10 years and 88.4% (95% CI: 75.2e95.1) at 15 years, which corresponded to the survival rates when socket revision was the endpoint, because there was no revision case in which only a stem or a modular head was revised during the follow-up period (Fig. 3a). When femoral component revision for any reason was the endpoint, the survival rate was 96.8% (95% CI: 92.6e98.7) at 10 years and 90.1% (95% CI: 75.9e96.4) at 15 years. On the other hand, the survival rates when socket and stem revision for aseptic loosening was the endpoint were 97.4% (95% CI: 93.3e99.0) and 100% at 10 years and 97.4% (95% CI: 93.3e99.0) and 97.1% (95% CI: 82.3e99.6) at 15 years, respectively (Fig. 3b). When radiographic loosening of the socket and stem was the endpoint, the survival rates were 97.2% (95% CI: 92.9e99.0) and 100% at 10
Table 1 Patient demographics and diagnoses with different stem shape.
Sex Male Female Height, cm Body weight, kg (range) BMI, kg/m2 (range) Diagnoses Primary or secondary osteoarthritis Rheumatoid arthritis ONFH Rapidly destructive osteoarthritis Follow-up period, years (range)
Roundback type
Flanged type
Total
2 (2 hips) 41 (44 hips) 148.1 ± 5.9 52.4 ± 9.3 23.9 ± 4.1
14 (15 hips) 99 (112 hips) 150.5 ± 7.5 52.4 ± 9.5 23.0 ± 3.3
16 (17 hips) 140 (156 hips) 149.8 (132e170) 52.4 (32e78) 23.3 kg/m2 (range, 15.0e32.1)
42 3 0 1 12.4 ± 2.0
115 8 3 1 11.3 ± 2.7
157 11 3 2 11.6 (5e17.8)
p 0.22
0.03 0.98 0.16 0.65
0.004
BMI, body mass index; ONFH, osteonecrosis of the femoral head.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
4
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
3.4. Clinical and radiographic results The size distribution of the stems, which were implanted in this series, and the radiographic results for each stem shape are shown in Table 2. RL was observed around the socket in 50 hips (32.3%), and was more likely to occur in zones 1 and 3. RL around the stem was observed in 26 hips (16.8%), which included 10 roundback type stems out of 44 hips (22.7%) and 16 flanged type stems out of 111 hips (14.4%). The difference was not significant (p ¼ 0.21). RL around the stem was more likely to occur in zones 1, 2, and 7. OL around the stem was identified in 6 hips (3.9%), which included 4 roundback type stems (including 2 femoral aseptic loosening cases) out of 44 hips (9.1%) and 2 flanged type stems out of 111 hips (1.8%). The difference was significant (p ¼ 0.03). Except for two loosening cases, OL around the stem was observed in zone 1 and 2, or zone 7. All 6 stems had neutral alignment. The occurrence rate of DFCH was 14.8% (23 hips), and it was observed in zone 3 in 16 cases, zone 4L in 7 cases, zone 4M in 3 cases, and zone 5 in 10 cases. The follow-up period, age, stem shape, stem size, and stem alignment were the significant factors associated with DFCH in the univariable logistic regression analysis, while only stem shape and stem alignment were the significant factors in the multivariable logistic regression analysis. DFCH was observed significantly more often in roundback type stems (34.1%) than in flanged type stems (7.2%) (OR:2.23, p ¼ 0.012) (Fig. 4a, Table 3). DFCH was significantly more observed with valgus alignment (34.8%) than neutral alignment (11.3%) (OR: 4.52, p ¼ 0.017; Fig. 4b, Table 3). 4. Discussion We reported the long-term clinical and radiographic results of primary THA using the Elite-Plus stem, and highlighted the effect of the stem's geometry on DFCH. As shown in Table 2, only 80% of the stems in this study obtained neutral alignment, and valgus alignment occurred relatively more often than varus alignment. This tendency was seen in both the roundback type and flanged type stems. Although OL was found around all the stems with neutral alignment, and stem alignment did not have a direct effect on the stem survival in this study, valgus alignment was not desirable for uniform stress distribution, because DFCH was found more in the cases with valgus alignment than in those with varus or neutral alignment.
Fig. 3. KaplaneMeier survivorship analysis with implant revision for any reason as the endpoint (a) and with stem revision for aseptic loosening as the second endpoint. (b). The solid lines indicate the survival rates, and the broken lines indicate the 95% confidence interval.
years, and 89.7% (95% CI: 73.1e96.6) and 98.1% (95% CI: 92.5e99.5) at 15 years, respectively. The log-rank test indicated that the difference of aseptic stem loosening-free survival between roundback and flanged type was not significant (p ¼ 0.053). Table 2 Radiographic assessment with different stem shape (N ¼ 155). Roundback, 44 (28.4%) Stem size CDH Size #1 Size #2 Size #3 Size #4 Stem alignment Neutral Valgus Varus RL Yes No OL Yes No DFCH Yes No
3 (1.9%) 27 (17.4%) 14 (9.0%)
Flanged type, 111 (71.6%)
Total
p
50 (32.3%) 49 (31.6%) 12 (7.7%) 0.95
35 7 2
89 16 6
124 (80%) 23 (14.8%) 8 (5.2%)
10 (22.7%) 34
16 (14.4%) 95
26 (16.8%) 129
4 (9.1%) 40
2 (1.8%) 109
6 (3.9%) 149
15 (34.1%) 29
8 (7.2%) 103
23 (14.8%) 132
0.21
0.03
<0.001
CDH: congenital dislocation of the hip, RL: radiolucent line around the stem, OL: osteolysis around the stem, DFCH: distal femoral cortical hypertrophy.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
Fig. 4. Occurrence rate of distal femoral cortical hypertrophy among stem shape (a) and alignment (b) variations.
While OL occurred significantly more in roundback type stems using chi-square test (Table 2), the results did not take into account the confounding factors such as the follow-up period. As femoral aseptic loosening occurred only in roundback type stems and DFCH was found significantly more, roundback type stems are possibly vulnerable to OL. The flanged Elite-Plus stem can promote cement pressurisation and increase the efficiency of cement function in load transmission [23]. This concept is expected to decrease aseptic loosening of the stem compared to Charnley low-friction arthroplasty stems. However, as von Schewelov et al. revealed using radiostereometric analysis, the Elite-Plus stem migrates more than the flanged Charnley stem [24], and many poor clinical and radiographic results have been reported [3e5,7,25]. Therefore, the difference of the roundback and flanged shape between the Charnley stem and the
5
Elite-Plus stem could possibly and significantly influence stem survival. We found that the occurrence rate of DFCH was 14.8%. Teusink et al. reviewed data on femoral remodelling around 106 Charnley stems and reported that the occurrence rate of DFCH was 17%, while Kobayashi et al. reviewed data on 326 Charnley stems and reported a rate of 29% [26,27]. The different rates might be due to the difference of the definition of DFCH as well as the difference of the shape between the original Charnley and Elite-Plus stems. In addition, the difference of the skeleton or body weight between Caucasian and Asian people might induce different femoral remodelling. The occurrence of DFCH is possibly due to bony reaction to the stress overload around the distal part of the stem. The lower occurrence rate of DFCH (7.2%) and the excellent radiographic survival rate of the flanged type stem in our series indicated that uniform stress distribution was obtained to some extent in the flanged type stem. On the other hand, multivariable logistic regression analysis revealed that DFCH appeared significantly more often in patients with the roundback type stem and valgus alignment of the stem than in those with the flanged type stem and neutral alignment. This result indicates that the roundback shape and valgus alignment might be unfavourable for uniform stress distribution. While Cho et al. reported that clinical outcomes and stem survival were not associated with DFCH [12], Tapadiya et al. reported that DFCH was correlated with worse clinical results [28]. Though DFCH was not associated with RL and OL around the stem in this study, further careful follow-up is necessary for patients with DFCH. There are many reports on the intermediate- or long-term result of the Elite-Plus stem. Kim et al. reported a high survival rate of the stem (99.5%) at 12 years postoperatively, with stem loosening as the endpoint [2]. On the other hand, Ollivere et al. reported that definite femoral loosening was present in 41 of 142 femoral components (28.9%) at 12 years postoperatively [4], and Walton et al. reported that loosening was observed in 52 out of 168 cases (31%) at 6.4 years postoperatively [3]. Hauptfleisch et al. also reported that the stem survival rate of 118 cases was 59% at 9 years postoperatively [25]. These authors surmised that these unsatisfactory results may be due to the stem shape, surgical procedure, type of bone cement, and cement technique, though they didn't refer to stem shape variation. In addition, Norton et al. reported that the Elite-Plus stem had catastrophic early failure when a zirconia ceramic head and cross-linked ultra-high molecular weight polyethylene (Hylamer) acetabular component were combined [5]. Therefore, it is highly likely that the cause of the unsatisfactory results of the Elite-Plus stem, which have been reported to date, is
Table 3 Logistic regression models identifying possible factors associated with DFCH. Covariate
Univariable model p Value
Adjusted OR (95% CI)
Follow-up period (months) Age, years Body mass index, kg/m2 Body weight, kg Stem shape (roundback/flange) Stem size (small/large) Stem alignment Valgus/neutral Varus/neutral Radiolucent line (yes/no) Osteolysis (yes/no)
1.03 0.91 1.00 0.99 6.66 3.61
(1.01e1.05)a (0.86e0.96)a (0.88e1.14)a (0.94e1.04)a (2.63e18.0) (1.27e13.0)
0.0012 0.007 0.97 0.69 <0.001 0.014
1.02 0.96 # # 2.23 0.93
4.19 1.12 1.25 1.15
(1.47e11.6) (0.058e7.0) (0.38e3.50) (0.059e7.62)
0.008 0.92 0.69 0.90
4.52 (1.31e16.0) 1.23 (0.060e8.92) # #
Crude OR (95% CI)
Final multivariable model
(0.99e1.04)a (0.89e1.02)a
(0.29e12.0) (0.19e4.55)
p Value 0.057 0.21 # # 0.012 0.93 0.017 0.86 # #
Abbreviations: DFCH, distal femoral cortical hypertrophy; OR, odds ratio; 95% CI, 95% confidence interval. # Not included. a Odds ratio per unit.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
6
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
not only due to the stem itself but also the other factors. Indeed, our study showed a satisfactory survival rate of 100% at 10 years and 97.1% at 15 years postoperatively with the use of conventional polyethylene sockets and medium-to-high viscosity cement when stem revision for aseptic loosening was used as the endpoint. Because excellent long-term results have been obtained in Asian people, who have a lower BMI than those of other ethnicities [1,2,6], relatively lower body weight or BMI was also supposed to contribute to the higher survival rates. This study has several limitations. First, we did not perform radiographic analyses for 18 out of 173 hips which were followed over 5 years, and the unevaluated 18 hips might have changed the overall radiographic results, although a telephone survey was performed. Second, we were only able to determine whether RL, OL, or DFCH occurred using the AP radiograph of the hip at the final follow-up or just before the revision surgery; therefore, we could not detect any abnormality on lateral hip radiographs. In addition, we did not determine when RL, OL, or DFCH appeared and expanded, though the onset of radiographic loosening was determined with serial radiographs. It is quite difficult to clearly determine the time point when such radiographic findings appear, and it was reported that the majority of DFCH of Charnley stem occurred within the initial 5 years [26]. Therefore, the results of this study presumably indicate the real effect of stem shape and alignment on DFCH. Third, aseptic stem loosening and OL around the stem occurred in only 2, and 6, respectively. Therefore we could not determine the factors which were associated with stem loosening and OL using multivariable analyses. Therefore, a further follow-up study may be necessary to detect the significant factors which cause aseptic stem loosening and OL. In conclusion, the present study demonstrates that the ElitePlus stem has excellent long-term clinical and radiographic results in the Japanese population. DFCH was observed significantly more around roundback type stems than around flanged type stems, and with valgus alignment than neutral alignment. This study was the first to reveal that DFCH was significantly influenced by the stem shape and alignment of the Elite-Plus stem, and may be helpful to understand the effect of stem shape and alignment on the stress distribution around the femoral stem. Conflict of interest The authors declare that they have no conflict of interest. References [1] Kim YH, Kook HK, Kim JS. Total hip replacement with a cementless acetabular component and a cemented femoral component in patients younger than fifty years of age. J Bone Joint Surg Am 2002 May;84-A(5):770e4. [2] Kim YH, Kim JS, Yoon SH. Long-term survivorship of the Charnley Elite Plus femoral component in young patients. J Bone Joint Surg Br 2007 Apr;89(4): 449e54. [3] Walton NP, Darrah C, Shepstone L, Donell ST, Phillips H. The Elite Plus total hip arthroplasty: the need for radiological surveillance. J Bone Joint Surg Br 2005 Apr;87(4):458e62. [4] Ollivere B, Darrah C, Brankin RC, Donell ST, Donnell ST, Walton NP. The continued value of clinical and radiological surveillance: the Charnley Elite Plus hip replacement system at 12 years. J Bone Joint Surg Br 2009 Jun;91(6): 720e4.
[5] Norton MR, Yarlagadda R, Anderson GH. Catastrophic failure of the Elite Plus total hip replacement, with a Hylamer acetabulum and Zirconia ceramic femoral head. J Bone Joint Surg Br 2002 Jul;84(5):631e5. [6] Irie T, Oyama M, Kita A, Sakamoto T, Funayama K. Medium-term result of Elite Plus hip arthroplasty: the second modular evolution of the original Charnley low-friction arthroplasty. J Orthop Sci 2012 Nov;17(6):699e704. [7] Rowsell M, Der Tavitian J, Birtwistle S, Power R. Survivorship of the Charnley Elite Plus cemented femoral stem. Int Orthop 2005 Aug;29(4):214e8. [8] Bourne RB, Oh I, Harris WH. Femoral cement pressurization during total hip arthroplasty. The role of different femoral stems with reference to stem size and shape. Clin Orthop Relat Res 1984 Mar;183:12e6. [9] Ritter MA, Fechtman RW. Distal cortical hypertrophy following total hip arthroplasty. J Arthroplasty 1988;3(2):117e21. [10] Katsimihas M, Katsimihas G, Lee MB, Learmonth ID. Distal femoral cortical hypertrophy: predisposing factors and their effect on clinical outcome. Hip Int 2006 JaneMar;16(1):18e22. [11] Sarmiento A, Gruen TA. Radiographic analysis of a low-modulus titaniumalloy femoral total hip component. Two to six-year follow-up. J Bone Joint Surg Am 1985 Jan;67(1):48e56. [12] Cho YJ, Chun YS, Rhyu KH, Baek JH, Liang H. Distal femoral cortical hypertrophy after hip arthroplasty using a cementless doubletapered femoral stem. J Orthop Surg (Hong Kong) 2016 Dec;24(3):317e22. [13] Inoue D, Kabata T, Maeda T, Kajino Y, Yamamoto T, Takagi T, Ohmori T, Tsuchiya H. The correlation between clinical radiological outcome and contact state of implant and femur using three-dimensional templating software in cementless total hip arthroplasty. Eur J Orthop Surg Traumatol 2016 Aug;26(6):591e8. [14] Maier MW, Streit MR, Innmann MM, Krüger M, Nadorf J, Kretzer JP, Ewerbeck V, Gotterbarm T. Cortical hypertrophy with a short, curved uncemented hip stem does not have any clinical impact during early follow-up. BMC Musculoskelet Disord 2015 Dec;16:371. [15] Kutzner KP, Freitag T, Donner S, Kovacevic MP, Bieger R. Outcome of extensive varus and valgus stem alignment in short-stem THA: clinical and radiological analysis using EBRA-FCA. Arch Orthop Trauma Surg 2017 Mar;137(3):431e9. [16] Mibe J, Imakiire A, Watanabe T, Fujie T. Results of total hip arthroplasty with bone graft and support ring for protrusio acetabuli in rheumatoid arthritis. J Orthop Sci 2005;10(1):8e14. [17] DeLee JG, Charnley J. Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop Relat Res 1976 NoveDec;121:20e32. [18] Gruen T, McNeice G, Amstutz H. “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res 1979 Jun;141:17e27. [19] Hodgkinson J, Shelley P, Wroblewski B. The correlation between the roentgenographic appearance and operative findings at the bone-cement junction of the socket in Charnley low friction arthroplasties. Clin Orthop Relat Res 1988 Mar;228:105e9. [20] Harris WH, McGann WA. Loosening of the femoral component after use of the medullary-plug cementing technique. Follow-up note with a minimum fiveyear follow-up. J Bone Joint Surg Am 1986 Sep;68(7):1064e6. [21] Fujita H, Katayama N, Iwase T, Otsuka H. Multi-center study of use of the Exeter stem in Japan: evaluation of 1000 primary THA. J Orthop Sci 2012;17(4):370e6. [22] Barrack RL, Mulroy RD, Harris WH. Improved cementing techniques and femoral component loosening in young patients with hip arthroplasty. A 12year radiographic review. J Bone Joint Surg Br 1992 May;74(3):385e9. [23] Wroblewski BM. The premature failure of the Charnley Elite-Plus stem. J Bone Joint Surg Br 2006 Jun;88(6):839. author reply -40. n L, Besjakov J, Carlsson A. The Elite-Plus stem mi[24] von Schewelov T, Sanze grates more than the flanged Charnley stem. Acta Orthop 2010 Jun;81(3): 280e5. [25] Hauptfleisch J, Glyn-Jones S, Beard DJ, Gill HS, Murray DW. The premature failure of the Charnley Elite-Plus stem: a confirmation of RSA predictions. J Bone Joint Surg Br 2006 Feb;88(2):179e83. [26] Teusink MJ, Callaghan KA, Klocke NF, Goetz DD, Callaghan JJ. Femoral remodeling around Charnley total hip arthroplasty is unpredictable. Clin Orthop Relat Res 2013 Dec;471(12):3838e46. [27] Kobayashi S, Eftekhar NS, Terayama K. Long term bone remodeling around the Charnley femoral prostheses. Clin Orthop Relat Res 1996 May;326: 162e73. [28] Tapadiya D, Walker RH, Schurman DJ. Prediction of outcome of total hip arthroplasty based on initial postoperative radiographic analysis. Matched, paired comparisons of failed versus successful femoral components. Clin Orthop Relat Res 1984 Jun;186:5e15.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy Koji Goto a, b, *, Yuki Furuya b, Kazuhiro Oda b, Ryosuke Minami b, Kaori Sano b, Masayuki Sugimoto b, Shuichi Matsuda a a b
Department of Orthopaedic Surgery, Kyoto University, Kyoto, Japan Department of Orthopaedic Surgery, Nagahama City Hospital, Shiga, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 15 July 2017 Received in revised form 23 November 2017 Accepted 6 December 2017 Available online xxx
Background: The Elite-Plus stem has two shape variations: roundback and flanged. The correlation between the radiographic results and stem geometry has not been previously investigated. The objective of this study was to evaluate the long-term primary total hip arthroplasty results using Elite-Plus stems, and the effect of stem geometry on radiographic distal femoral cortical hypertrophy. Methods: We retrospectively evaluated, radiographically, 156 patients (173 hips) who underwent total hip arthroplasty between April 1998 and November 2005, and were followed up for >5 years, postoperatively. Radiographic factors affecting distal femoral cortical hypertrophy were analysed using multivariable logistic regression analysis. Results: The mean follow-up period was 11.6 (5e17.8) years. During follow-up, femoral components were revised in 7 hips; one was revised due to aseptic loosening. Another femoral component was loosened and waiting for revision. The 10- and 15-year survival rates for aseptic stem loosening were 100% and 98.1% (95% CI: 92.5e99.5), respectively. Distal femoral cortical hypertrophy occurred in 23 hips (14.8%), and more often with roundback type (34.1%) than with flanged type (7.2%). Distal femoral cortical hypertrophy was observed in 34.8% of hips with valgus alignment, 11.3% with neutral alignment, and 12.5% with varus alignment. Multivariable logistic regression analysis showed that roundback stem shape and valgus stem alignment significantly affected the occurrence of distal femoral cortical hypertrophy. Conclusions: The Elite-Plus stem has excellent long-term clinical and radiographic results in Japanese patients. The occurrence of distal femoral cortical hypertrophy significantly depends on the shape and alignment of Elite-Plus stems. © 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
1. Introduction The Charnley Elite-Plus stem (Depuy, Warsaw, IN, USA) was developed as the successor model to the original Charnley stem and became commercially available in 1994. This stem has had mixed clinical results [1e7]. Walton et al. reported that 16.4% (26 of 159) of Elite-Plus stems had either been revised or had definite evidence of radiological loosening of the component at a mean of 6.4 years,
* Corresponding author. Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Shogoin, Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan. Fax: þ81 75 751 8409. E-mail address: [email protected] (K. Goto).
postoperatively [4]; however, Kim et al. reported that the stem survival rate at 12 years was 99% [2]. The Elite-Plus stem is characterised by its specific flanged shape, and has two shape variations according to its size: roundback type for congenital dislocation of the hip (CDH) and stem size 1, flanged type for stems larger than size 3, and both types for size 2 (Fig. 1a). The shape variations cannot be distinguished in plain radiographs (Fig. 1b). Although the stem's shape has a significant effect on bone cement pressurisation and thus the long-term radiographic results, no long-term results have been reported with reference to the different shapes of the Elite-Plus stem [8]. On the other hand, distal femoral cortical hypertrophy (DFCH), the typical radiographic appearance of which is shown in Fig. 1b, is
https://doi.org/10.1016/j.jos.2017.12.003 0949-2658/© 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
2
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
2. Materials and methods 2.1. Patient demographics The study protocol was approved by the institutional review board of our hospital. Between April 1998 and November 2005, 199 consecutive primary THAs (in 182 patients) were performed using a cemented Elite-Plus femoral stem (Depuy, Warsaw, IN, USA). Of the 182 patients, 19 were lost to follow-up, and 7 patients died from unrelated causes within 5 years postoperatively. Thus, we retrospectively reviewed data on 173 hips (in 156 patients) with a postoperative follow-up of more than 5 years (follow-up rate: 90.1%). Among them, 18 hips (in 18 patients) were excluded from radiographic evaluation, because 16 had no radiographs available at the final follow-up because the patient died or moved to another region, and 2 hips were infected within 5 years. We telephoned the 16 patients or their families and asked them about their condition and whether revision surgeries had been performed. We performed radiographic evaluation for 155 hips (Fig. 2). 2.2. Surgical procedure and rehabilitation programme THA was performed through direct lateral approaches, including a Charnley transtrochanteric approach in 30 (17.3%), Dall's approach in 141 (81.5%), and a Hardinge approach in 2 (1.2%). Cemented acetabular components were used in all hips, including LPW (DePuy) in 7 (4.0%), FPW (DePuy) in 118 (68.2%), Offset bore (DePuy) in 1 (0.6%), Ogee (DePuy) in 46 (26.6%), and unknown in 1 (0.6%). All acetabular components were made of conventional polyethylene. For the femoral prostheses, an Elite-Plus stem (DePuy) and an Orthron modular head (22.225 mm in diameter) (DePuy) were used in all cases. Both acetabular and femoral components were fixed with the third-generation cementing technique, and the cement used was CMW1 (DePuy) in 14 (9.0%) cases, Endurance (DePuy) in 131 (84.5%), and both cements in 10 (6.5%). Postoperative gait exercise with partial weight bearing started 2e4 weeks after surgery, and full weight bearing was allowed 4e8 weeks after surgery. 2.3. Clinical and radiographic evaluation Hip function was evaluated using the Japanese Orthopaedic Association (JOA) score [16], which is based on pain (40%), range of movement (20%), ability to walk (20%), and activities of daily living (20%). The total score is 100 points for a normal hip. We evaluated radiographs for 155 hips for which annual standard anteroposterior
Fig. 1. (a) Two shape variations of the Elite Plus stem: right side, roundback type; left side, flanged type. The flange curved medially in the distal portion, which is different from the design of the original Charnley stem. (b) A postoperative AP radiograph of a 69-year-old female: right hip (flanged type-stem) at 12 years postoperatively, left hip (roundback type-stem) at 13 years postoperatively. Arrows indicate DFCH.
commonly considered to be caused by stress overload around the femoral stem tip, and many have reported the relevance between clinical outcomes or radiographic factors and DFCH [9e15]. However, DFCH around the Elite-Plus stem with the two shape variances has not been reported. In this retrospective study, we evaluated the long-term clinical and radiographic results of primary total hip arthroplasty (THA) using the Elite-Plus stem, and examined the correlation between the stem geometry and radiographic results.
Fig. 2. Follow-up flowchart of the patients.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
(AP) radiographs were available. Two of the authors who were not involved in the initial surgeries performed the radiographic evaluations. The authors discussed the radiographic parameters and determined them through consensus. The radiolucent line (RL) was evaluated in all zones around the socket as described by DeLee and Charnley [17], while RL and osteolysis (OL) around the femoral prosthesis, as described by Gruen et al. [18]. Stem alignment was evaluated on the postoperative AP radiographs, and valgus or varus alignment less than 2 was categorised as neutral. Radiographic loosening was assessed according to the criteria of Hodgkinson et al. for acetabular components [19] and the criteria of Harris et al. for femoral prostheses [20]; radiographic loosening was confirmed when complete demarcation or implant migration was detected. DFCH were evaluated according to the modified Gruen zones described by Fujita et al. [21]. Kappa coefficients for interobserver variability of radiographic loosening, OL, and DFCH were 1, 0.66, and 0.86, respectively. 2.4. Statistical analysis KaplaneMeier survival analysis was used to evaluate the time to implant loosening seen on radiographs, revision surgery for any reason, and revision surgery for aseptic loosening for both acetabular and femoral components. The log-rank test was used to evaluate the relationships between aseptic stem loosening-free survival and stem shape. Patients' demographic data and radiographic results for roundback and flanged type were compared using unpaired T-test or chi-square test. We also analysed possible factors associated with DFCH, which included age, body weight, body mass index (BMI), follow-up period, stem shape, stem size, stem alignment, RL around the stem, and OL around the stem, using univariable and multivariable logistic regression analyses. To analyse the effect of the size of the femoral component, CDH, size 1, and size 2 were consolidated and designated as small stem, while size 3 and 4 as large stem. All statistical analyses were performed with JMP IN version 10.0.2 (SAS Institute Inc., Cary, NC, USA) or Excel Statistics 2015 for Windows (Social Survey Research Information Co., Ltd., Tokyo, Japan). Two-sided p-values < 0.05 were considered significant. 3. Results 3.1. Patient demographics Of the 156 patients, 16 were men (17 hips) and 140 were women (156 hips) with a mean age at the time of surgery of 63.8 years (range, 42e84). Mean body weight and body mass index (BMI) for the men and women were 52.4 kg (range, 32e78 kg) and 23.3 kg/
3
m2 (range, 15.0e32.1 kg/m2), respectively. The diagnosis was osteoarthritis in 157 hips (90.8%), rheumatoid arthritis in 11 (6.4%), osteonecrosis of the femoral head in 3 (1.7%), and rapidly destructive osteoarthritis in 2 (1.2%) (Table 1). There were significant differences on the height and follow-up period between roundback and flanged type (Table 1). Although the perioperative radiographs were not available for all patients, serial radiographs taken during postoperative follow-up predicted that the cementation of all the prostheses would be graded A or B, according to the criteria of Barrack et al. [22]. 3.2. Surgical results The mean follow-up period was 11.6 years (range, 5e17.8). The mean JOA score improved significantly from 44.8 (range, 13e82) preoperatively to 86.4 (range, 59e100) at the final follow-up. Of the 173 THAs, 10 hips required revision during the follow-up period. Sockets were revised in 10 hips, and femoral components were revised in 7 hips. Sockets were revised due to aseptic loosening in 4 hips, infection in 3, wear and osteolysis in 2, and recurrent dislocation in 1. Femoral component revision was performed due to aseptic loosening in 1 hip, infection in 3, and implant mismatch or for optimal exposure of the acetabulum during the socket revision procedure in 3. In another 6 cases, radiographic loosening of either the acetabular component (5 cases) or the femoral component (1 case) was confirmed during the follow-up period. The former cases did not undergo revision, because the patients had no symptoms around the hip, and the latter case was waiting for revision. Roundback type stems were used in both cases of femoral aseptic loosening. 3.3. Survival rates The KaplaneMeier survivorship analysis with implant revision for any reason as the endpoint showed a survival rate of 95.0% (95% CI: 90.2e97.5) at 10 years and 88.4% (95% CI: 75.2e95.1) at 15 years, which corresponded to the survival rates when socket revision was the endpoint, because there was no revision case in which only a stem or a modular head was revised during the follow-up period (Fig. 3a). When femoral component revision for any reason was the endpoint, the survival rate was 96.8% (95% CI: 92.6e98.7) at 10 years and 90.1% (95% CI: 75.9e96.4) at 15 years. On the other hand, the survival rates when socket and stem revision for aseptic loosening was the endpoint were 97.4% (95% CI: 93.3e99.0) and 100% at 10 years and 97.4% (95% CI: 93.3e99.0) and 97.1% (95% CI: 82.3e99.6) at 15 years, respectively (Fig. 3b). When radiographic loosening of the socket and stem was the endpoint, the survival rates were 97.2% (95% CI: 92.9e99.0) and 100% at 10
Table 1 Patient demographics and diagnoses with different stem shape.
Sex Male Female Height, cm Body weight, kg (range) BMI, kg/m2 (range) Diagnoses Primary or secondary osteoarthritis Rheumatoid arthritis ONFH Rapidly destructive osteoarthritis Follow-up period, years (range)
Roundback type
Flanged type
Total
2 (2 hips) 41 (44 hips) 148.1 ± 5.9 52.4 ± 9.3 23.9 ± 4.1
14 (15 hips) 99 (112 hips) 150.5 ± 7.5 52.4 ± 9.5 23.0 ± 3.3
16 (17 hips) 140 (156 hips) 149.8 (132e170) 52.4 (32e78) 23.3 kg/m2 (range, 15.0e32.1)
42 3 0 1 12.4 ± 2.0
115 8 3 1 11.3 ± 2.7
157 11 3 2 11.6 (5e17.8)
p 0.22
0.03 0.98 0.16 0.65
0.004
BMI, body mass index; ONFH, osteonecrosis of the femoral head.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
4
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
3.4. Clinical and radiographic results The size distribution of the stems, which were implanted in this series, and the radiographic results for each stem shape are shown in Table 2. RL was observed around the socket in 50 hips (32.3%), and was more likely to occur in zones 1 and 3. RL around the stem was observed in 26 hips (16.8%), which included 10 roundback type stems out of 44 hips (22.7%) and 16 flanged type stems out of 111 hips (14.4%). The difference was not significant (p ¼ 0.21). RL around the stem was more likely to occur in zones 1, 2, and 7. OL around the stem was identified in 6 hips (3.9%), which included 4 roundback type stems (including 2 femoral aseptic loosening cases) out of 44 hips (9.1%) and 2 flanged type stems out of 111 hips (1.8%). The difference was significant (p ¼ 0.03). Except for two loosening cases, OL around the stem was observed in zone 1 and 2, or zone 7. All 6 stems had neutral alignment. The occurrence rate of DFCH was 14.8% (23 hips), and it was observed in zone 3 in 16 cases, zone 4L in 7 cases, zone 4M in 3 cases, and zone 5 in 10 cases. The follow-up period, age, stem shape, stem size, and stem alignment were the significant factors associated with DFCH in the univariable logistic regression analysis, while only stem shape and stem alignment were the significant factors in the multivariable logistic regression analysis. DFCH was observed significantly more often in roundback type stems (34.1%) than in flanged type stems (7.2%) (OR:2.23, p ¼ 0.012) (Fig. 4a, Table 3). DFCH was significantly more observed with valgus alignment (34.8%) than neutral alignment (11.3%) (OR: 4.52, p ¼ 0.017; Fig. 4b, Table 3). 4. Discussion We reported the long-term clinical and radiographic results of primary THA using the Elite-Plus stem, and highlighted the effect of the stem's geometry on DFCH. As shown in Table 2, only 80% of the stems in this study obtained neutral alignment, and valgus alignment occurred relatively more often than varus alignment. This tendency was seen in both the roundback type and flanged type stems. Although OL was found around all the stems with neutral alignment, and stem alignment did not have a direct effect on the stem survival in this study, valgus alignment was not desirable for uniform stress distribution, because DFCH was found more in the cases with valgus alignment than in those with varus or neutral alignment.
Fig. 3. KaplaneMeier survivorship analysis with implant revision for any reason as the endpoint (a) and with stem revision for aseptic loosening as the second endpoint. (b). The solid lines indicate the survival rates, and the broken lines indicate the 95% confidence interval.
years, and 89.7% (95% CI: 73.1e96.6) and 98.1% (95% CI: 92.5e99.5) at 15 years, respectively. The log-rank test indicated that the difference of aseptic stem loosening-free survival between roundback and flanged type was not significant (p ¼ 0.053). Table 2 Radiographic assessment with different stem shape (N ¼ 155). Roundback, 44 (28.4%) Stem size CDH Size #1 Size #2 Size #3 Size #4 Stem alignment Neutral Valgus Varus RL Yes No OL Yes No DFCH Yes No
3 (1.9%) 27 (17.4%) 14 (9.0%)
Flanged type, 111 (71.6%)
Total
p
50 (32.3%) 49 (31.6%) 12 (7.7%) 0.95
35 7 2
89 16 6
124 (80%) 23 (14.8%) 8 (5.2%)
10 (22.7%) 34
16 (14.4%) 95
26 (16.8%) 129
4 (9.1%) 40
2 (1.8%) 109
6 (3.9%) 149
15 (34.1%) 29
8 (7.2%) 103
23 (14.8%) 132
0.21
0.03
<0.001
CDH: congenital dislocation of the hip, RL: radiolucent line around the stem, OL: osteolysis around the stem, DFCH: distal femoral cortical hypertrophy.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
Fig. 4. Occurrence rate of distal femoral cortical hypertrophy among stem shape (a) and alignment (b) variations.
While OL occurred significantly more in roundback type stems using chi-square test (Table 2), the results did not take into account the confounding factors such as the follow-up period. As femoral aseptic loosening occurred only in roundback type stems and DFCH was found significantly more, roundback type stems are possibly vulnerable to OL. The flanged Elite-Plus stem can promote cement pressurisation and increase the efficiency of cement function in load transmission [23]. This concept is expected to decrease aseptic loosening of the stem compared to Charnley low-friction arthroplasty stems. However, as von Schewelov et al. revealed using radiostereometric analysis, the Elite-Plus stem migrates more than the flanged Charnley stem [24], and many poor clinical and radiographic results have been reported [3e5,7,25]. Therefore, the difference of the roundback and flanged shape between the Charnley stem and the
5
Elite-Plus stem could possibly and significantly influence stem survival. We found that the occurrence rate of DFCH was 14.8%. Teusink et al. reviewed data on femoral remodelling around 106 Charnley stems and reported that the occurrence rate of DFCH was 17%, while Kobayashi et al. reviewed data on 326 Charnley stems and reported a rate of 29% [26,27]. The different rates might be due to the difference of the definition of DFCH as well as the difference of the shape between the original Charnley and Elite-Plus stems. In addition, the difference of the skeleton or body weight between Caucasian and Asian people might induce different femoral remodelling. The occurrence of DFCH is possibly due to bony reaction to the stress overload around the distal part of the stem. The lower occurrence rate of DFCH (7.2%) and the excellent radiographic survival rate of the flanged type stem in our series indicated that uniform stress distribution was obtained to some extent in the flanged type stem. On the other hand, multivariable logistic regression analysis revealed that DFCH appeared significantly more often in patients with the roundback type stem and valgus alignment of the stem than in those with the flanged type stem and neutral alignment. This result indicates that the roundback shape and valgus alignment might be unfavourable for uniform stress distribution. While Cho et al. reported that clinical outcomes and stem survival were not associated with DFCH [12], Tapadiya et al. reported that DFCH was correlated with worse clinical results [28]. Though DFCH was not associated with RL and OL around the stem in this study, further careful follow-up is necessary for patients with DFCH. There are many reports on the intermediate- or long-term result of the Elite-Plus stem. Kim et al. reported a high survival rate of the stem (99.5%) at 12 years postoperatively, with stem loosening as the endpoint [2]. On the other hand, Ollivere et al. reported that definite femoral loosening was present in 41 of 142 femoral components (28.9%) at 12 years postoperatively [4], and Walton et al. reported that loosening was observed in 52 out of 168 cases (31%) at 6.4 years postoperatively [3]. Hauptfleisch et al. also reported that the stem survival rate of 118 cases was 59% at 9 years postoperatively [25]. These authors surmised that these unsatisfactory results may be due to the stem shape, surgical procedure, type of bone cement, and cement technique, though they didn't refer to stem shape variation. In addition, Norton et al. reported that the Elite-Plus stem had catastrophic early failure when a zirconia ceramic head and cross-linked ultra-high molecular weight polyethylene (Hylamer) acetabular component were combined [5]. Therefore, it is highly likely that the cause of the unsatisfactory results of the Elite-Plus stem, which have been reported to date, is
Table 3 Logistic regression models identifying possible factors associated with DFCH. Covariate
Univariable model p Value
Adjusted OR (95% CI)
Follow-up period (months) Age, years Body mass index, kg/m2 Body weight, kg Stem shape (roundback/flange) Stem size (small/large) Stem alignment Valgus/neutral Varus/neutral Radiolucent line (yes/no) Osteolysis (yes/no)
1.03 0.91 1.00 0.99 6.66 3.61
(1.01e1.05)a (0.86e0.96)a (0.88e1.14)a (0.94e1.04)a (2.63e18.0) (1.27e13.0)
0.0012 0.007 0.97 0.69 <0.001 0.014
1.02 0.96 # # 2.23 0.93
4.19 1.12 1.25 1.15
(1.47e11.6) (0.058e7.0) (0.38e3.50) (0.059e7.62)
0.008 0.92 0.69 0.90
4.52 (1.31e16.0) 1.23 (0.060e8.92) # #
Crude OR (95% CI)
Final multivariable model
(0.99e1.04)a (0.89e1.02)a
(0.29e12.0) (0.19e4.55)
p Value 0.057 0.21 # # 0.012 0.93 0.017 0.86 # #
Abbreviations: DFCH, distal femoral cortical hypertrophy; OR, odds ratio; 95% CI, 95% confidence interval. # Not included. a Odds ratio per unit.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003
6
K. Goto et al. / Journal of Orthopaedic Science xxx (2017) 1e6
not only due to the stem itself but also the other factors. Indeed, our study showed a satisfactory survival rate of 100% at 10 years and 97.1% at 15 years postoperatively with the use of conventional polyethylene sockets and medium-to-high viscosity cement when stem revision for aseptic loosening was used as the endpoint. Because excellent long-term results have been obtained in Asian people, who have a lower BMI than those of other ethnicities [1,2,6], relatively lower body weight or BMI was also supposed to contribute to the higher survival rates. This study has several limitations. First, we did not perform radiographic analyses for 18 out of 173 hips which were followed over 5 years, and the unevaluated 18 hips might have changed the overall radiographic results, although a telephone survey was performed. Second, we were only able to determine whether RL, OL, or DFCH occurred using the AP radiograph of the hip at the final follow-up or just before the revision surgery; therefore, we could not detect any abnormality on lateral hip radiographs. In addition, we did not determine when RL, OL, or DFCH appeared and expanded, though the onset of radiographic loosening was determined with serial radiographs. It is quite difficult to clearly determine the time point when such radiographic findings appear, and it was reported that the majority of DFCH of Charnley stem occurred within the initial 5 years [26]. Therefore, the results of this study presumably indicate the real effect of stem shape and alignment on DFCH. Third, aseptic stem loosening and OL around the stem occurred in only 2, and 6, respectively. Therefore we could not determine the factors which were associated with stem loosening and OL using multivariable analyses. Therefore, a further follow-up study may be necessary to detect the significant factors which cause aseptic stem loosening and OL. In conclusion, the present study demonstrates that the ElitePlus stem has excellent long-term clinical and radiographic results in the Japanese population. DFCH was observed significantly more around roundback type stems than around flanged type stems, and with valgus alignment than neutral alignment. This study was the first to reveal that DFCH was significantly influenced by the stem shape and alignment of the Elite-Plus stem, and may be helpful to understand the effect of stem shape and alignment on the stress distribution around the femoral stem. Conflict of interest The authors declare that they have no conflict of interest. References [1] Kim YH, Kook HK, Kim JS. Total hip replacement with a cementless acetabular component and a cemented femoral component in patients younger than fifty years of age. J Bone Joint Surg Am 2002 May;84-A(5):770e4. [2] Kim YH, Kim JS, Yoon SH. Long-term survivorship of the Charnley Elite Plus femoral component in young patients. J Bone Joint Surg Br 2007 Apr;89(4): 449e54. [3] Walton NP, Darrah C, Shepstone L, Donell ST, Phillips H. The Elite Plus total hip arthroplasty: the need for radiological surveillance. J Bone Joint Surg Br 2005 Apr;87(4):458e62. [4] Ollivere B, Darrah C, Brankin RC, Donell ST, Donnell ST, Walton NP. The continued value of clinical and radiological surveillance: the Charnley Elite Plus hip replacement system at 12 years. J Bone Joint Surg Br 2009 Jun;91(6): 720e4.
[5] Norton MR, Yarlagadda R, Anderson GH. Catastrophic failure of the Elite Plus total hip replacement, with a Hylamer acetabulum and Zirconia ceramic femoral head. J Bone Joint Surg Br 2002 Jul;84(5):631e5. [6] Irie T, Oyama M, Kita A, Sakamoto T, Funayama K. Medium-term result of Elite Plus hip arthroplasty: the second modular evolution of the original Charnley low-friction arthroplasty. J Orthop Sci 2012 Nov;17(6):699e704. [7] Rowsell M, Der Tavitian J, Birtwistle S, Power R. Survivorship of the Charnley Elite Plus cemented femoral stem. Int Orthop 2005 Aug;29(4):214e8. [8] Bourne RB, Oh I, Harris WH. Femoral cement pressurization during total hip arthroplasty. The role of different femoral stems with reference to stem size and shape. Clin Orthop Relat Res 1984 Mar;183:12e6. [9] Ritter MA, Fechtman RW. Distal cortical hypertrophy following total hip arthroplasty. J Arthroplasty 1988;3(2):117e21. [10] Katsimihas M, Katsimihas G, Lee MB, Learmonth ID. Distal femoral cortical hypertrophy: predisposing factors and their effect on clinical outcome. Hip Int 2006 JaneMar;16(1):18e22. [11] Sarmiento A, Gruen TA. Radiographic analysis of a low-modulus titaniumalloy femoral total hip component. Two to six-year follow-up. J Bone Joint Surg Am 1985 Jan;67(1):48e56. [12] Cho YJ, Chun YS, Rhyu KH, Baek JH, Liang H. Distal femoral cortical hypertrophy after hip arthroplasty using a cementless doubletapered femoral stem. J Orthop Surg (Hong Kong) 2016 Dec;24(3):317e22. [13] Inoue D, Kabata T, Maeda T, Kajino Y, Yamamoto T, Takagi T, Ohmori T, Tsuchiya H. The correlation between clinical radiological outcome and contact state of implant and femur using three-dimensional templating software in cementless total hip arthroplasty. Eur J Orthop Surg Traumatol 2016 Aug;26(6):591e8. [14] Maier MW, Streit MR, Innmann MM, Krüger M, Nadorf J, Kretzer JP, Ewerbeck V, Gotterbarm T. Cortical hypertrophy with a short, curved uncemented hip stem does not have any clinical impact during early follow-up. BMC Musculoskelet Disord 2015 Dec;16:371. [15] Kutzner KP, Freitag T, Donner S, Kovacevic MP, Bieger R. Outcome of extensive varus and valgus stem alignment in short-stem THA: clinical and radiological analysis using EBRA-FCA. Arch Orthop Trauma Surg 2017 Mar;137(3):431e9. [16] Mibe J, Imakiire A, Watanabe T, Fujie T. Results of total hip arthroplasty with bone graft and support ring for protrusio acetabuli in rheumatoid arthritis. J Orthop Sci 2005;10(1):8e14. [17] DeLee JG, Charnley J. Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop Relat Res 1976 NoveDec;121:20e32. [18] Gruen T, McNeice G, Amstutz H. “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res 1979 Jun;141:17e27. [19] Hodgkinson J, Shelley P, Wroblewski B. The correlation between the roentgenographic appearance and operative findings at the bone-cement junction of the socket in Charnley low friction arthroplasties. Clin Orthop Relat Res 1988 Mar;228:105e9. [20] Harris WH, McGann WA. Loosening of the femoral component after use of the medullary-plug cementing technique. Follow-up note with a minimum fiveyear follow-up. J Bone Joint Surg Am 1986 Sep;68(7):1064e6. [21] Fujita H, Katayama N, Iwase T, Otsuka H. Multi-center study of use of the Exeter stem in Japan: evaluation of 1000 primary THA. J Orthop Sci 2012;17(4):370e6. [22] Barrack RL, Mulroy RD, Harris WH. Improved cementing techniques and femoral component loosening in young patients with hip arthroplasty. A 12year radiographic review. J Bone Joint Surg Br 1992 May;74(3):385e9. [23] Wroblewski BM. The premature failure of the Charnley Elite-Plus stem. J Bone Joint Surg Br 2006 Jun;88(6):839. author reply -40. n L, Besjakov J, Carlsson A. The Elite-Plus stem mi[24] von Schewelov T, Sanze grates more than the flanged Charnley stem. Acta Orthop 2010 Jun;81(3): 280e5. [25] Hauptfleisch J, Glyn-Jones S, Beard DJ, Gill HS, Murray DW. The premature failure of the Charnley Elite-Plus stem: a confirmation of RSA predictions. J Bone Joint Surg Br 2006 Feb;88(2):179e83. [26] Teusink MJ, Callaghan KA, Klocke NF, Goetz DD, Callaghan JJ. Femoral remodeling around Charnley total hip arthroplasty is unpredictable. Clin Orthop Relat Res 2013 Dec;471(12):3838e46. [27] Kobayashi S, Eftekhar NS, Terayama K. Long term bone remodeling around the Charnley femoral prostheses. Clin Orthop Relat Res 1996 May;326: 162e73. [28] Tapadiya D, Walker RH, Schurman DJ. Prediction of outcome of total hip arthroplasty based on initial postoperative radiographic analysis. Matched, paired comparisons of failed versus successful femoral components. Clin Orthop Relat Res 1984 Jun;186:5e15.
Please cite this article in press as: Goto K, et al., Long-term results of total hip arthroplasty using Charnley Elite-Plus stem and the effect of stem geometry on radiographic distal femoral cortical hypertrophy, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.003