Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head
by
, , , and
Seneki Kobayashi
1,2,*
,
Nobuhiko Sugano
1,3,
Wataru Ando
1,4,
Wakaba Fukushima
1,5,
Kyoko Kondo
6 and
Takashi Sakai
1,7 1
The Investigation Committee on Osteonecrosis of the Femoral Head Under the Ministry of Health, Labour and Welfare, Tokyo 100-8959, Japan
2
Department of Orthopaedic Surgery, Suwa Red Cross Hospital, Suwa 392-8510, Japan
3
Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita 565-0871, Japan
4
Department of Orthopaedic Surgery, Kansai Rosai Hospital, Amagasaki 660-0064, Japan
5
Department of Public Health, Osaka Metropolitan University Graduate School of Medicine, Osaka 545-8585, Japan
6
Research Support Platform, Osaka Metropolitan University Graduate School of Medicine, Osaka 545-8585, Japan
7
Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube 755-8505, Japan
*
Author to whom correspondence should be addressed.
Materials 2025, 18(9), 2125; https://doi.org/10.3390/ma18092125
Submission received: 27 February 2025
/
Revised: 18 April 2025
/
Accepted: 28 April 2025
/
Published: 6 May 2025
(This article belongs to the Special Issue Recent Progress in Bioceramics and Their Composites)
Abstract
:A nationwide multicenter follow-up cohort study of hip-replacement arthroplasties performed for nontraumatic osteonecrosis of the femoral head (ONFH) was conducted to clarify factors associated with need for reoperation. We analyzed 7393 arthroplasties including 6284 total hip arthroplasties (THAs), 886 bipolar hemiarthroplasties (BPs), 188 total resurfacing arthroplasties, and 35 hemi-resurfacing arthroplasties (hRSs). The identified risk factors were combined systemic steroid use and excessive alcohol consumption (both ONFH-associated factors), a lateral approach, alumina BPs (aBPs), and hRSs, which were reported previously. The present study performed further analyses separately for THAs and BPs to clarify risk factors in each surgical group. A Cox proportional-hazard model identified the following risk factors: the acetabular-articulating materials of conventional polyethylene (cPE) and metal in the THAs and both ONFH-associated factors, minimum-incision surgery (MIS), and aBPs in the BPs. The risk factors were specific to each surgical group. In the ONFH patients, when performing THA, cPE and metal are not recommended as the acetabular-articulating material. When performing BP, patients with both ONFH-associated factors should be treated carefully, and the employment of MIS and use of aBP are not good strategies.
1. Introduction
Nontraumatic osteonecrosis of the femoral head (ONFH) patients undergoing hip-replacement arthroplasties are generally younger, more often of the male gender [1], and at higher risks of postoperative dislocation [2,3] and a need for reoperation [4,5,6,7,8], compared with patients undergoing the procedures mainly for osteoarthrosis (OA). Hip arthroplasty practice has changed noticeably. In total hip arthroplasty (THA), acetabular liners made of highly (approximately 10 Mrad) cross-linked polyethylene (HXLPE) and larger prosthetic heads have increasingly been used. In bipolar hemiarthroplasties (BPs), usually performed for ONFH before the development of OA, many modifications have been made to improve their poor results [9,10]. To reduce osteolysis due to polyethylene debris generated by neck–outer head impingement in BP [11,12], a new type of BPs (nBPs) with a smooth, small-diameter (approximately 10 mm) neck without any sharp corners began to replace other BPs (oBPs) [1]. As contemporary femoral prostheses tended to have a neck with a larger diameter, ‘small-diameter’ was excluded from the definition, which described BPs with a smooth neck (sBPs) and the others with a rough-surfaced neck (rBPs). Alumina BPs (aBPs, with the outer surface of the outer head made of alumina ceramic) were developed to surpass the durability of metal BPs (mBPs). BPs with HXLPE in the outer head (hBPs) were also developed to improve the survivorship of BPs with conventional polyethylene (cPE) (cBPs). However, their efficacy has not been clinically proven. Therefore, hip-replacement arthroplasties performed for OFNH should be monitored; this was conducted in a nationwide multicenter follow-up cohort study.
In a survey conducted in 2023, we analyzed arthroplasties including THAs, BPs, total resurfacing arthroplasties (tRSs), and hemi-resurfacing arthroplasties (hRSs). The identified risk factors were combined systemic steroid use and excessive alcohol consumption (both ONFH-associated factors), a lateral approach, aBPs, and hRSs, which were reported previously [13]. However, it was not clear which risk factors were applicable to which surgical treatments. Our hypothesis was that risk factors could be specific to each surgical treatment. Therefore, the present study performed further analyses separately for THAs and BPs to clarify risk factors in each surgical group.
2. Materials and Methods
2.1. THAs and BPs Analyzed for Factors Related to Need for Reoperation
The previous study [13] described the method of the nationwide multicenter follow-up cohort study of hip-replacement arthroplasties performed for ONFH and the demographic and operative details of the 7393 arthroplasties (after exclusion of 58 infected hips and 43 ABS THAs with very poor survivorship from the entire cohort of 7494 arthroplasties observed in the 2023 survey) that were analyzed for factors related to need for reoperation. They included 6284 THAs (85.0%), 886 BPs (12.0%), 188 tRSs (2.5%), and 35 hRSs (0.5%) (Figure 1). THAs and tRSs were performed in all ONFH stages, while BPs and hRSs were performed mainly before stage 4 (OA). The 886 BPs could be divided into two in four ways. As for hip prostheses and their providers, 81 types of acetabular components were provided by 15 companies and 137 types of femoral components by 18 companies.
2.2. Statistical Analyses
Factors related to need for reoperation were analyzed with a Cox proportional-hazard model using IBM SPSS statistics version 29 (IBM Corp, Armonk, NY, USA). Univariate analyses were first performed by applying the model to each of the demographic and operative variables with a significance level of p < 0.1. Variables with p < 0.1 were then examined together using the model with a significance level of p < 0.05 (multivariate analysis). Effects of the identified risk factors on the survivorship of hip arthroplasties were illustrated with the Kaplan–Meier estimator (with log-rank tests) with a significance level of p < 0.05. A χ2 test was used to compare the prevalence of categorical data and a t-test was used to compare means with a significance level of p < 0.05.
2.3. Ethical Approvals
Ethical approvals for this study were comprehensively obtained at three representative institutions: Shinshu University School of Medicine (8 January 2008, No. 1043), Suwa Red Cross Hospital (27 November 2014, No. 26–23 and 26 March 2019, No. 30–19), and Osaka University Graduate School of Medicine (29 January 2021, No. 20461). This study was carried out in accordance with the World Medical Association Declaration of Helsinki. All participants included in the study gave informed consent and agreed to participate in this study and to have their data published in a journal.
3. Results
3.1. Comparison of Demographic and Surgical Variables Between THAs and BPs
The demographic and operative features of the 6284 THAs and the 886 BPs and their comparisons are listed in Table 1. They were different between the two surgical groups except for patient weight.
3.2. Analyses of the 6284 THAs
3.2.1. Cox Proportional-Hazard Model Analyses
The follow-up of the 6284 THAs ranged from 0.1 to 27 (mean of 6.5) years, during which 189 hips (3.0%) needed reoperation. The univariate analyses identified five of the variables listed in Table 1 with p < 0.1 (Table 2). However, in the χ2 tests, incision length, femoral head material, and head diameter were strongly related (p < 0.001). THAs with a 22 mm prosthetic head were performed with conventional incision in 92.2% of cases, and the 22 mm heads were made of metal in 78.2% of cases. Therefore, incision length and head material were not included in the next multivariate analyses. As the remaining three variables had been reported concerning the survivorship of THAs and without a strong relationship between them, they were examined together with the model.
The multivariate survivorship analysis identified only acetabular-articulating material as a risk factor with p < 0.05 (Table 3). Compared with HXLPE or MXLPE, cPE and metal (cobalt–chrome or metal-on-metal THA) had inferior survivorship (p < 0.001 and p = 0.028, respectively), whereas that of ceramic (ceramic-on-ceramic THA) did not differ (p = 0.765).
3.2.2. Survivorship Illustrated with Kaplan–Meier Estimator
The Kaplan–Meier estimator illustrated the effects of the acetabular-articulating materials on the survivorship of THAs with need for reoperation as the endpoint (Figure 2). Compared with the HXLPE or MXLPH group, the cPE and metal (metal-on-metal THA) groups had inferior survivorship, but the ceramic (ceramic-on-ceramic THA) group did not. The rates of need for reoperation were also different among them in a χ2-test (p < 0.001): 1.8% in the HXLPE or MXLPE group, 11.6% in the cPE group, 6.6% in the metal group, and 4.3% in the ceramic group.
Regarding reasons for need for reoperation, in the HXLPE or MXLPE group, recurrent dislocation was at the top, followed by periprosthetic femoral fracture (Table 4). In the cPE group, the most frequent three reasons were osteolysis, polyethylene wear and/or breakage, and recurrent dislocation. The top reason was adverse reaction to metal debris (ARMD) in the metal (metal-on-metal THA) group and recurrent dislocation in the ceramic (ceramic-on-ceramic THA) group.
3.3. Analyses of the 886 BPs
3.3.1. Cox Proportional-Hazard Model Analyses
The follow-up of the 886 BPs ranged from 0.1 to 27 (mean, 9.6) years, during which 47 hips (5.3%) needed reoperation. The univariate analyses identified three of the variables listed in Table 1 with p < 0.1, i.e., ONFH-associated factors, incision length, and aBPs (Table 5). Without strong relationship among them, they were examined together with the model.
In the multivariate survivorship analysis, all the three variables were confirmed as risk factors with p < 0.05 (Table 6). Combined systemic steroid use and excessive alcohol consumption (both ONFH-associated factors) had a higher risk, with no associated factors as a reference (p = 0.008). Compared with conventional incision, minimal-incision surgery (MIS, defined as the use of a ≤ 10 cm incision to complete a hip arthroplasty) had a higher risk (p < 0.001). The aBPs had a higher risk than the mBPs (p = 0.004).
3.3.2. Survivorship Illustrated with Kaplan–Meier Estimator
The Kaplan–Meier estimator illustrated the effects of the three identified risk factors on the survivorship of BPs with need for reoperation as the endpoint. Among the ONFH-associated factor groups, the group with both factors was at a higher risk than the other groups (Figure 3). The other groups were not different from one another in survivorship. The MIS group had lower survivorship than the conventional incision group (Figure 4). The aBPs had lower survivorship than the mBPs (Figure 5). The rates of need for reoperation were also different between them in a χ2-test (p = 0.014): 4.2% in the mBPs and 8.4% in the aBPs. In both groups, the proximal migration of the outer head was the main reason for need for reoperation in 17 of 27 (63.0%) of the mBPs and 13 of 20 (65.0%) of the aBPs (Table 7).
4. Discussion
In the previous report, regarding need for reoperation, analyses of 7393 arthroplasties including 6284 THAs, 886 BPs, 188 tRSs, and 35 hRSs identified the following risk factors: both ONFH-associated factors, a lateral approach, aBPs, and hRSs [13]. However, it was not clear which risk factors were applicable to which surgical treatments. In the present study, further analyses performed separately for the 6284 THAs and 886 BPs revealed that risk factors were specific to each surgical group: acetabular-articulating material in the THAs and having both ONFH-associated factors, MIS, and aBPs in the BPs.
4.1. Acetabular-Articulating Material Is a Determinant of Survivorship of THAs
In the Australian registry, the cumulative percent revision of primary THAs performed for OA was higher with cPE than with HXLPE, and it was higher with metal-on-metal bearing than with metal-on-HXLPE bearing, but it was not different between ceramic-on-ceramic and metal-on-HXLPE bearings [4]. In a cohort study of 253 metal-on-metal THAs with a median follow-up of 11.5 years, 34 hips were revised, with survival rates of 89.6% at 10 years and 82.9% at 14.6 years, and 19 of them (55.9%) were revised due to ARMD [14]. In the present study, compared with the HXLPE or MXLPH group, the cPE and the metal groups had inferior survivorship; survival rates with HXLPE or MXLPH, cPE, and metal were 90%, 78%, and 83% at 20 years, respectively, whereas that of the ceramic group did not differ (Figure 2). Reasons for need for reoperation in the HXLPE or MXLPE group included recurrent dislocation at the top, followed by periprosthetic femoral fracture (Table 4). In the ceramic group, recurrent dislocation was also at the top. In the cPE group, the most frequent three reasons were osteolysis, polyethylene wear and/or breakage, and recurrent dislocation, which could be related, to some extent, to the inferior properties of cPE compared with those of HXLPE or MXLPE. In the metal group, ARMD was the top reason. Therefore, acetabular-articulating material was an important determinant of the survivorship of the THAs.
4.2. Combined Existence of Both ONFH-Associated Factors Affects Survivorship of BPs
Systemic steroid use [6] and excessive alcohol consumption [15,16] were risk factors associated with reoperation in THAs for ONFH. In the present study, the combined existence of both factors was a risk factor related to need for reoperation not in the THAs but in the BPs. This is reported for the first time to our knowledge.
4.3. MIS Affects Survivorship of BPs
As for MIS, in a report based on data from the Norwegian Arthroplasty Register, the revision rates associated with the MIS anterior and anterolateral approaches were not increased compared with those of the conventional posterior and direct lateral approaches [17]. We could not find any study that analyzed influence of MIS on the reoperation risk of BPs. However, the reoperation risk of the BPs performed with MIS was higher than that of the PBs performed using conventional incisions.
4.4. The Material of the Outer Head Articulating with Cartilage Is a Determinant of Survivorship of BPs
The patho-mechanism of the inferior durability of the aBPs was discussed in the previous report [13]. In short, articulation with the BP outer head could be harmful to the acetabular cartilage, and the better lubrication of cartilage with aBP than with mBP could increase articulation in aBP, leading to the proximal migration of the outer head and pain, resulting in a higher risk of reoperation in aBPs than in mBPs.
4.5. Little Difference Based on Component Fixation in Survivorship of THAs
Component fixation has been many hip surgeons’ interest in relation to the durability of hip prostheses. In the Australian registry, in the cumulative percent revision of primary THAs performed for OA, there was little difference in outcomes based on fixation (cemented, hybrid, or cementless), except for patients aged ≥ 75 years, where the revision rate was lower when either hybrid or cemented fixation was used [4]. As for younger patients, in a study analyzing the most commonly used uncemented, hybrid, and fully cemented implant combinations in the New Zealand registry, in 40–55-year-old patients, revision rates were comparable between the uncemented and the hybrid implant combinations, whereas the cemented implant combination exhibited a higher revision rate. In <40-year-old patients, the revision rate for the hybrid implant combination was significantly lower than that for the uncemented implant combination [18]. In the present study of THAs and BPs performed for ONFH, fixation (uncemented/cement and surface finish of femoral stem) was not associated with need for reoperation.
4.6. Limitations
Some patient-related and operative data were lacking, e.g., surgical experience. Hip arthroplasty practice changed over the observation period in surgical approach, component fixation, acetabular-articulating material, and the material and diameter of the femoral head, although all of them were analyzed in the present study. Information on complications unrelated to reoperation could not be obtained, given the constraints involving the 31 institutions. THAs and BPs performed only for Japanese ONFH patients were analyzed. All of them warrant further research.
5. Conclusions
The present further analyses performed separately for the 6284 THAs and 886 BPs revealed that risk factors associated with need for reoperation were specific to each surgical group: acetabular-articulating material in the THAs and both ONFH-associated factors, MIS, and aBPs in the BPs. The articulating materials, i.e., the acetabular-articulating material in the THAs and the alumina outer surface of the outer head in the BPs, were important determinants in the survivorship of hip prostheses in ONFH patients.
Author Contributions
Conceptualization, S.K., N.S., W.F., K.K. and T.S.; methodology, S.K., N.S., W.F., K.K. and T.S.; software, S.K., W.F. and K.K.; validation, S.K., N.S., W.A., W.F., K.K. and T.S.; formal analysis, S.K., W.F. and K.K.; investigation, S.K., W.F. and K.K.; resources, N.S., W.A. and T.S.; data curation, S.K., W.F. and K.K.; writing—original draft preparation, S.K.; writing—review and editing, S.K., N.S., W.A., W.F., K.K. and T.S.; visualization, S.K.; supervision, N.S. and T.S.; project administration, S.K., N.S., W.A. and T.S.; funding acquisition, N.S. and T.S. All authors have read and agreed to the published version of the manuscript.
Funding
This study was supported by a research grant from the Health Labour Sciences Research Grant, the Ministry of Health, Labour and Welfare, Japan (23FC0201). The funder had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
Institutional Review Board Statement
Ethical approvals for this study were comprehensively obtained at three representative institutions: Shinshu University School of Medicine (8 January 2008, No. 1043), Suwa Red Cross Hospital (27 November 2014, No. 26–23 and 26 March 2019, No. 30–19), and Osaka University Graduate School of Medicine (29 January 2021, No. 20461). This study was carried out in accordance with the World Medical Association Declaration of Helsinki.
Informed Consent Statement
All participants included in this study were informed and agreed to participate in this study and to have their data published in a journal.
Data Availability Statement
The data that support the findings for this study are available to other researchers from the corresponding author upon reasonable request. The data are not publicly available due to the conditions included in the ethical approvals for this study.
Acknowledgments
The authors express their sincere gratitude to orthopedic surgeons listed in the following who participated in this study. Institutions (researchers [currently working at other hospitals]) in geographical order from north to south: Asahikawa Medical University (Hiroshi Ito, Hiromasa Tanino), Hokkaido University (Daisuke Takahashi, Tomohiro Shimizu, Takuji Miyazaki, Takuya Ogawa), Sapporo Medical University (Satoshi Nagoya, Ima Kosukegawa), Yamagata University (Michiaki Takagi, Juji Ito), Chiba University (Junichi Nakamura, Shigeo Hagiwara, Yuya Kawarai), Dokkyo Medical University Saitama Medical Center (Tetsuya Jinno, Gaku Koyano, Ryota Shinada, Tetsuya Tachibana, Moe Suzuki), The University of Tokyo (Sakae Tanaka, Takeyuki Tanaka, Naoto Kaminaga), Institute of Science Tokyo (Ryohei Takada, Kazumasa Miyatake), Tokyo Medical University (Kengo Yamamoto, Takaaki Shishido, Toshinori Masaoka, Toshiyuki Tateiwa, Tsunehito Ishida), Yokohama City University (Yutaka Inaba, Hyonmin Choe, Hiroyuki Ike), Showa University Fujigaoka Hospital (Minoru Watanabe, Tsubasa Ishikawa, Itaru Kachi), Shinshu University ([Hiroyuki Kodaira], Hiroshi Horiuchi), Kanazawa University (Tamon Kabata), Kanazawa Medical University (Ayumi Kaneuji, Toru Ichiseki), Nagoya University (Yasuhiko Takegami, Yusuke Osawa), Mie University (Akihiro Sudo, Masahiro Hasegawa, Yohei Naito), Kyoto University (Yutaka Kuroda, Toshiyuki Kawai, Yaichiro Okuzu, Yugo Morita, Shuichi Matsuda), Osaka University (Kazuma Takashima, Keisuke Uemura, [Masaki Takao], Hidetoshi Hamada), Osaka National Hospital (Hidenobu Miki, Makoto Kitada, Yoshichika Hashimoto, Makoto Iwasa), Kansai Rosai Hospital (Takeshi Ogawa, Tsuyoshi Koyama), Osaka Metropolitan University (Yoichi Ohta, Ryo Sugama), Hiroshima University (Takeshi Shoji, Hideki Shozen, Shinichi Ueki, Hiroki Kaneta), Yamaguchi University (Takashi Imagama, Tomoya Okazaki, Yuta Matsuki, Takehiro Kaneoka, Takehiro Kawakami, Kazuhiro Yamazaki), Ehime University (Naohiko Mashima, Masaki Takao), Kyushu University (Yasuharu Nakashima, Goro Motomura, Ryosuke Yamaguchi, Takeshi Utsunomiya, Noriko Yamamoto, Hidenao Tanaka, Yusuke Ayabe, Kosei Sakamoto), Fukuoka University (Fumihiro Yoshimura, Yoshiaki Hideshima, Taiki Matsunaga, Hajime Seo, Koichi Kinoshita, Takuaki Yamamoto), Saga University (Masaaki Mawatari, Shunsuke Kawano, Masanori Fujii, Masaya Ueno), Nagasaki University (Makoto Osaki, Ko Chiba, Kyosuke Kobayashi, Kazuteru Shiraishi), Oita University (Nobuhiro Kaku), Miyazaki University (Etsuo Chosa, Takero Sakamoto, Yoichiro Yamaguchi), and University of the Ryukyus (Satoshi Nakasone, Masamichi Onaga, Takahiro Igei, Fumiyuki Washizaki).
Conflicts of Interest
The authors declare no conflict of interest.
References
- Kobayashi, S.; Kubo, T.; Iwamoto, Y.; Fukushima, W.; Sugano, N. Nationwide multicenter follow-up cohort study of hip arthro-plasties performed for osteonecrosis of the femoral head. Int. Orthop. 2018, 42, 1661–1668. [Google Scholar] [CrossRef] [PubMed]
- Kunutsor, S.K.; Barrett, M.C.; Beswick, A.D.; Judge, A.; Blom, A.W.; Wylde, V.; Whitehouse, M.R. Risk factors for dislocation after primary total hip replacement: A systematic review and meta-analysis of 125 studies involving approximately five million hip re-placements. Lancet Rheumatol. 2019, 1, e111–e121. [Google Scholar] [CrossRef] [PubMed]
- Zhang, Z.; Chi, J.; Driskill, E.; Mont, M.; Jones, L.C.; Cui, Q. Effect of patient age on total hip arthroplasty outcomes in patients who have osteonecrosis of the femoral head compared to patients who have hip osteoarthritis. J. Arthroplast. 2024, 39, 1535–1544. [Google Scholar] [CrossRef] [PubMed]
- Australian Orthopaedic Association National Joint Replacement Registry. AOANJRR 2024 Annual Report. Available online: https://aoanjrr.sahmri.com/annual-reports-2024 (accessed on 9 April 2025).
- Bergh, C.; Fenstad, A.M.; Furnes, O.; Garellick, G.; Havelin, L.I.; Overgaard, S.; Pedersen, A.B.; Mäkelä, K.T.; Pulkkinen, P.; Mohaddes, M.; et al. Increased risk of revision in patients with non-traumatic femoral head necrosis. Acta Orthop. 2014, 85, 11–17. [Google Scholar] [CrossRef] [PubMed]
- Hart, A.; Janz, V.; Trousdale, R.T.; Sierra, R.J.; Berry, D.J.; Abdel, M.P. Long-term survivorship of total hip arthroplasty with highly cross-linked polyethylene for osteonecrosis. J. Bone Joint Surg. Am. 2019, 101, 1563–1568. [Google Scholar] [CrossRef] [PubMed]
- Radl, R.; Hungerford, M.; Materna, W.; Rehak, P.; Windhager, R. Higher failure rate and stem migration of an uncemented femoral component in patients with femoral head osteonecrosis than in patients with osteoarthrosis. Acta Orthop. 2005, 76, 49–55. [Google Scholar] [CrossRef] [PubMed]
- Salman, L.A.; Hantouly, A.T.; Khatkar, H.; Al-Ani, A.; Abudalou, A.; Al-Juboori, M.; Ahmed, G. The outcomes of total hip replacement in osteonecrosis versus osteoarthritis: A systematic review and meta-analysis. Int. Orthop. 2023, 47, 3043–3052. [Google Scholar] [CrossRef] [PubMed]
- Lee, S.B.; Sugano, N.; Nakata, K.; Matsui, M.; Ohzono, K. Comparison between bipolar hemiarthroplasty and THA for osteonecrosis of the femoral head. Clin. Orthop. Relat. Res. 2004, 424, 161–165. [Google Scholar] [CrossRef] [PubMed]
- Hwang, K.; Kim, Y.H.; Kim, Y.S.; Choi, I.Y. Is bipolar hemiarthroplasty a reliable option for Ficat stage III osteonecrosis of the femoral head? 15- to 24-year follow-up study. Arch. Orthop. Trauma Surg. 2012, 132, 1789–1796. [Google Scholar] [CrossRef] [PubMed]
- Kobayashi, S.; Takaoka, K.; Tsukada, A.; Ueno, M. Polyethylene wear from femoral bipolar neck-cup impingement as a cause of femoral prosthetic loosening. Arch. Orthop. Trauma Surg. 1998, 117, 390–391. [Google Scholar] [CrossRef] [PubMed]
- Moriya, M.; Uchiyama, K.; Takahira, N.; Fukushima, K.; Yamamoto, T.; Hoshi, K.; Itoman, M.; Takaso, M. Evaluation of bipolar hemiarthroplasty for the treatment of steroid-induced osteonecrosis of the femoral head. Int. Orthop. 2012, 36, 2041–2047. [Google Scholar] [CrossRef] [PubMed]
- Kobayashi, S.; Sugano, N.; Ando, W.; Fukushima, W.; Kondo, K.; Sakai, T. Concerns with alumina bipolar hemiarthroplasties compared to metal bipolar hemiarthroplasties when performed for nontraumatic osteonecrosis of the femoral head. Int. Orthop. 2024, 48, 2535–2543. [Google Scholar] [CrossRef]
- Holappa, E.; Kettunen, J.; Miettinen, H.; Kröger, H.; Miettinen, S. Long-term survival analysis of cementless large-diameter head metal-on-metal total hip arthroplasty. Arch. Orthop. Trauma Surg. 2023, 143, 4437–4446. [Google Scholar] [CrossRef] [PubMed]
- Ponzio, D.Y.; Pitta, M.; Carroll, K.M.; Alexiades, M. Hip arthroplasty for osteonecrosis of the femoral head secondary to alcohol abuse. Arthroplast. Today 2018, 5, 172–175. [Google Scholar] [CrossRef] [PubMed]
- Yuan, B.; Taunton, M.J.; Trousdale, R.T. Total hip arthroplasty for alcoholic osteonecrosis of the femoral head. Orthopedics 2009, 32, 400–405. [Google Scholar] [CrossRef] [PubMed]
- Mjaaland, K.E.; Svenningsen, S.; Fenstad, A.M.; Havelin, L.I.; Furnes, O.; Nordsletten, L. Implant survival after minimally invasive anterior or anterolateral vs. conventional posterior or direct lateral approach: An analysis of 21,860 total hip arthroplasties from the Norwegian Arthroplasty Register (2008 to 2013). J. Bone Joint Surg. Am. 2017, 99, 840–847. [Google Scholar] [CrossRef] [PubMed]
- Boyle, A.B.; Zhu, M.; Frampton, C.; Vane, A.; Poutawera, V. Comparing uncemented, hybrid and cemented primary total hip arthroplasty in young patients, a New Zealand Joint Registry study. Arch Orthop Trauma Surg. 2022, 142, 2371–2380. [Google Scholar] [CrossRef] [PubMed]
Figure 1.
The flowchart of selecting the study groups of 6284 primary total hip arthroplasties (THAs) and 886 bipolar hemiarthroplasties (BPs) from the originally registered cohort of 7494 hip arthroplasties. tRSs: total resurfacing arthroplasties; hRSs: hemi-resurfacing arthroplasties; nBPs: a new type of BPs; oBPs: other BPs; sBPs: BPs with a smooth neck; rBPs: other BPs with a rough-surfaced neck; mBPs: BPs with a metal outer head; and aBPs: BPs with an alumina outer head. Kobayashi et al. 2024 [13].
Figure 1.
The flowchart of selecting the study groups of 6284 primary total hip arthroplasties (THAs) and 886 bipolar hemiarthroplasties (BPs) from the originally registered cohort of 7494 hip arthroplasties. tRSs: total resurfacing arthroplasties; hRSs: hemi-resurfacing arthroplasties; nBPs: a new type of BPs; oBPs: other BPs; sBPs: BPs with a smooth neck; rBPs: other BPs with a rough-surfaced neck; mBPs: BPs with a metal outer head; and aBPs: BPs with an alumina outer head. Kobayashi et al. 2024 [13].
Figure 2.
The cumulative survival of total hip arthroplasties (THAs) among types of acetabular-articulating materials with need for reoperation as the endpoint. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene. Survival rates for ceramic, HXLPE or MXLPH, metal, and cPE were 97%, 98%, 94%, and 93% at 10 years and 93%, 90%, 83%, and 78% at 20 years, respectively. Compared with the HXLPE or MXLPH group, the metal and cPE groups had inferior survivorship (p = 0.004 and p < 0.001, respectively), but the ceramic group did not (p = 0.657).
Figure 2.
The cumulative survival of total hip arthroplasties (THAs) among types of acetabular-articulating materials with need for reoperation as the endpoint. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene. Survival rates for ceramic, HXLPE or MXLPH, metal, and cPE were 97%, 98%, 94%, and 93% at 10 years and 93%, 90%, 83%, and 78% at 20 years, respectively. Compared with the HXLPE or MXLPH group, the metal and cPE groups had inferior survivorship (p = 0.004 and p < 0.001, respectively), but the ceramic group did not (p = 0.657).
Figure 3.
The cumulative survival of bipolar hemiarthroplasties (BPs) among osteonecrosis of the femoral head (ONFH)-associated factor groups with need for reoperation as the endpoint. Steroid: systemic steroid use. Alcohol: excessive alcohol consumption. Both: both ONFH-associated factors. None: no ONFH-associated factors. Survival rates with none, steroid, alcohol, and both were 100%, 97%, 95%, and 82% at 10 years and 94%, 90%, 93%, and 82% at 15 years, respectively. The group with both ONFH-associated factors had lower survivorship than the other groups (p ≤ 0.001). The other groups were not different from one another in survivorship (p ≥ 0.075).
Figure 3.
The cumulative survival of bipolar hemiarthroplasties (BPs) among osteonecrosis of the femoral head (ONFH)-associated factor groups with need for reoperation as the endpoint. Steroid: systemic steroid use. Alcohol: excessive alcohol consumption. Both: both ONFH-associated factors. None: no ONFH-associated factors. Survival rates with none, steroid, alcohol, and both were 100%, 97%, 95%, and 82% at 10 years and 94%, 90%, 93%, and 82% at 15 years, respectively. The group with both ONFH-associated factors had lower survivorship than the other groups (p ≤ 0.001). The other groups were not different from one another in survivorship (p ≥ 0.075).
Figure 4.
The cumulative survival of bipolar hemiarthroplasties (BPs) between incision length groups with need for reoperation as the endpoint. Conventional: conventional incision. MIS: minimum-incision surgery. Their survival rates were 97% and 86% at 10 years, respectively. The MIS group had lower survivorship than the conventional group (p < 0.001).
Figure 4.
The cumulative survival of bipolar hemiarthroplasties (BPs) between incision length groups with need for reoperation as the endpoint. Conventional: conventional incision. MIS: minimum-incision surgery. Their survival rates were 97% and 86% at 10 years, respectively. The MIS group had lower survivorship than the conventional group (p < 0.001).
Figure 5.
The cumulative survival of bipolar hemiarthroplasties (BPs) between the groups of materials of the outer surface of the outer head with need for reoperation as the endpoint. mBP: BPs with a metal outer head. aBP: BPs with an alumina outer head. Their survival rates were 97% and 93% at 10 years and 89% and 74% at 20 years, respectively. The aBPs had lower survivorship than the mBPs (p = 0.008).
Figure 5.
The cumulative survival of bipolar hemiarthroplasties (BPs) between the groups of materials of the outer surface of the outer head with need for reoperation as the endpoint. mBP: BPs with a metal outer head. aBP: BPs with an alumina outer head. Their survival rates were 97% and 93% at 10 years and 89% and 74% at 20 years, respectively. The aBPs had lower survivorship than the mBPs (p = 0.008).
Table 1.
Comparison of characteristics (means ± SDs or percentages) of 6284 THAs and 886 BPs performed for ONFH using t-test and χ2 test.
Table 1.
Comparison of characteristics (means ± SDs or percentages) of 6284 THAs and 886 BPs performed for ONFH using t-test and χ2 test.
| Variable | THAs | BPs | p-Value | |
|---|---|---|---|---|
| Patient age (years) | 52.0 ± 14.34 | 49.2 ± 14.21 | <0.001 | |
| Male gender (%) | 54.0 | 58.1 | 0.024 | |
| Height (cm) | 162.1 ± 9.26 | 163.0 ± 9.10 | 0.011 | |
| Weight (kg) | 61.3 ± 12.84 | 60.8 ± 11.83 | 0.242 | |
| BMI (body mass index) (kg/m2) | 23.23 ± 3.951 | 22.80 ± 3.589 | 0.002 | |
| ONFH-associated factor (%) | Systemic steroid use | 59.9 | 53.9 | <0.001 |
| Excessive alcohol consumption | 27.0 | 33.5 | ||
| None of them | 10.8 | 9.3 | ||
| Both of them | 2.3 | 3.3 | ||
| ONFH stage (%) | 2 (without collapse of FH) | 2.7 | 4.6 | <0.001 |
| 3 (collapse of FH) | 49.8 | 89.6 | ||
| 4 (osteoarthrosis) | 47.5 | 5.8 | ||
| Previous surgery in index joint (%) | Yes (joint-preserving surgery) | 8.1 | 4.3 | <0.001 |
| Surgical approach (%) | Posterior | 58.5 | 87.6 | <0.001 |
| Anterior or anterolateral | 22.3 | 1.9 | ||
| Lateral | 19.2 | 10.5 | ||
| Incision length (%) | Conventional | 68.9 | 94.0 | <0.001 |
| MIS | 31.1 | 6.0 | ||
| Cemented fixation (%) | Acetabular component | 2.3 | NA | NA |
| Femoral component | 14.4 | 8.2 | <0.001 | |
| Surface finish of femoral stem | Grid blast (for bone on growth) | 7.8 | 4.3 | <0.001 |
| Porous with/without coating | 69.9 | 83.6 | ||
| Cement with/without polish | 13.9 | 7.1 | ||
| Others | 8.4 | 5.0 | ||
| Acetabular-articulating material in THAs and inner articulating surface of outer head in BPs (%) | HXLPE | 61.4 | 13.1 | NA |
| MXLPE | 21.3 | 0 | ||
| cPE | 9.3 | 86.9 | ||
| Cobalt–chrome | 4.3 | 0 | ||
| Ceramic | 3.7 | 0 | ||
| Femoral head material in THAs and inner head material in BPs (%) | Ceramic | 64.4 | 40.2 | NA |
| Cobalt–chrome | 28.2 | 53.4 | ||
| Oxidized zirconium | 5.6 | 1.8 | ||
| Stainless steel | 1.8 | 4.6 | ||
| Head diameter in THAs and inner head diameter in BPs (%) | ≥36 mm | 21.4 | 0 | NA |
| 32 mm | 36.3 | 0.6 | ||
| 28 mm | 23.9 | 18.2 | ||
| 26 mm | 14.5 | 32.5 | ||
| 22 mm | 3.9 | 48.7 | ||
SDs: standard deviations. THAs: total hip arthroplasties. BPs: bipolar hemiarthroplasties. ONFH: osteonecrosis of the femoral head. FH: the femoral head. MIS: minimum-incision surgery (defined as the use of a ≤ 10 cm incision to complete a hip arthroplasty). NA: not applicable. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene.
Table 2.
Univariate analysis of each variable applying the COX proportional-hazard model to the 6284 THAs performed for osteonecrosis of the femoral head (ONFH).
Table 2.
Univariate analysis of each variable applying the COX proportional-hazard model to the 6284 THAs performed for osteonecrosis of the femoral head (ONFH).
| Variable | Factor | Hazard Ratio (95% CI) | p-Value |
|---|---|---|---|
| Patient age (years) | Increment of 1 | 1.01 (0.99–1.02) | 0.146 |
| Gender | Female | Reference | |
| Male | 1.02 (0.75–1.37) | 0.920 | |
| Height (cm) | Increment of 1 | 1.00 (0.98–1.02) | 0.997 |
| Weight (kg) | Increment of 1 | 0.99 (0.98–1.01) | 0.333 |
| BMI (body mass index) (kg/m2) | Increment of 1 | 0.98 (0.94–1.02) | 0.247 |
| ONFH-associated factor | Systemic steroid use | 0.94 (0.57–1.55) | 0.807 |
| Excessive alcohol consumption | 1.31 (0.76–2.25) | 0.326 | |
| None of them | Reference | ||
| Both of them | 1.82 (0.72–4.60) | 0.203 | |
| ONFH stage | 2 or 3 (before osteoarthrosis) | 0.84 (0.61–1.14) | 0.253 |
| 4 (osteoarthrosis) | Reference | ||
| Previous hip surgery in index joint | No | Reference | |
| Yes | 1.16 (0.72–1.86) | 0.554 | |
| Surgical approach | Posterior | 0.71 (0.50–1.01 | 0.054 |
| Anterior or anterolateral | 0.42 (0.23–0.79) | 0.007 | |
| Lateral | Reference | ||
| Incision length | Conventional | Reference | |
| MIS | 0.53 (0.33–0.83) | 0.005 | |
| Acetabular component fixation | Uncemented | Reference | |
| Cemented | 1.71 (0.84–3.49) | 0.137 | |
| Femoral component fixation | Uncemented | Reference | |
| Cemented | 1.04 (0.67–1.62) | 0.860 | |
| Surface finish of femoral stem | Grid blast (for bone on growth) | Reference | |
| Porous with/without coating | 0.81 (0.048–1.36) | 0.429 | |
| Cement with/without polish | 0.73 (0.38–1.42) | 0.353 | |
| Others | 0.59 (0.29–1.24) | 0.164 | |
| Acetabular-articulating material | HXLPE or MXLPE | Reference | |
| cPE | 2.82 (2.00–3.98) | <0.001 | |
| Metal (metal-on-metal THA) | 2.12 (1.25–3.59) | 0.005 | |
| Ceramic (ceramic-on-ceramic THA) | 1.11 (0.57–2.15) | 0.765 | |
| Femoral head material | Metal | Reference | |
| Ceramic | 0.50 (0.37–0.68) | <0.001 | |
| Head diameter | ≥36 mm | 0.38 (0.21–0.67) | <0.001 |
| 32 mm | 0.30 (0.17–0.51) | <0.001 | |
| 28 mm | 0.36 (0.22–0.58) | <0.001 | |
| 26 mm | 0.41 (0.26–0.66) | <0.001 | |
| 22 mm | Reference |
THAs: total hip arthroplasties. ONFH: osteonecrosis of the femoral head. CI: confidence interval. MIS: minimum-incision surgery. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene.
Table 3.
Multivariate analysis applying the COX proportional-hazard model to the 6284 THAs performed for ONFH.
Table 3.
Multivariate analysis applying the COX proportional-hazard model to the 6284 THAs performed for ONFH.
| Variable | Factor | Hazard Ratio (95% CI) | p-Value |
|---|---|---|---|
| Surgical approach | Posterior | 0.69 (0.47–1.00) | 0.050 |
| Anterior or anterolateral | 0.52 (0.27–1.00) | 0.051 | |
| Lateral | Reference | ||
| Acetabular-articulating material | HXLPE or MXLPE | Reference | |
| cPE | 2.55 (1.69–3.84) | <0.001 | |
| Metal (metal-on-metal THA) | 2.15 (1.08–4.28) | 0.028 | |
| Ceramic (ceramic-on-ceramic THA) | 1.27 (0.63–2.57) | 0.503 | |
| Head diameter | ≥36 mm | 0.62 (0.28–1.36) | 0.233 |
| 32 mm | 0.68 (0.35–1.32) | 0.250 | |
| 28 mm | 0.60 (0.34–1.03) | 0.065 | |
| 26 mm | 0.68 (0.40–1.13) | 0.138 | |
| 22 mm | Reference |
THAs: total hip arthroplasties. ONFH: osteonecrosis of the femoral head. CI: confidence interval. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene.
Table 4.
Reasons for need for reoperation regarding acetabular-articulating materials in the 6284 THAs performed for ONFH.
Table 4.
Reasons for need for reoperation regarding acetabular-articulating materials in the 6284 THAs performed for ONFH.
| Reasons for Need for Reoperation (n) | HXLPE or MXLPE (5194) | cPE (584) | Metal (274) | Ceramic (232) | Total (6284) |
|---|---|---|---|---|---|
| Recurrent dislocation | 35 | 13 | 3 | 6 | 57 |
| Periprosthetic femoral fracture | 20 | 5 | 0 | 1 | 26 |
| Osteolysis | 6 | 18 | 2 | 0 | 26 |
| Polyethylene wear and/or breakage | 3 | 17 | 1 | 0 | 21 |
| Stem loosening | 9 | 8 | 0 | 1 | 18 |
| Socket loosening | 9 | 2 | 2 | 1 | 14 |
| Adverse reaction to metal debris | 1 | 0 | 8 | 0 | 9 |
| Others (n ≤ 3 for each) | 10 | 5 | 2 | 1 | 18 |
| Total (%) | 93 (1.8%) | 68 (11.6%) | 18 (6.6%) | 10 (4.3%) | 189 (3.0%) |
THAs: total hip arthroplasties. ONFH: osteonecrosis of the femoral head. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. MXLPE: moderately (5 to 7.5 Mrad) cross-linked polyethylene. cPE: conventional polyethylene.
Table 5.
Univariate analysis of each variable applying the COX proportional-hazard model to the 886 BPs performed for ONFH.
Table 5.
Univariate analysis of each variable applying the COX proportional-hazard model to the 886 BPs performed for ONFH.
| Variable | Factor | Hazard Ratio (95% CI) | p-Value |
|---|---|---|---|
| Patient age (years) | Increment of 1 | 0.99 (0.97–1.01) | 0.304 |
| Gender | Female | Reference | |
| Male | 1.05 (0.59–1.88) | 0.868 | |
| Height (cm) | Increment of 1 | 1.01 (0.98–1.05) | 0.452 |
| Weight (kg) | Increment of 1 | 1.01 (0.99–1.04) | 0.351 |
| BMI (kg/m2) | Increment of 1 | 1.03 (0.95–1.13) | 0.480 |
| ONFH-associated factor | Systemic steroid use | 1.96 (0.46–8.28) | 0.363 |
| Excessive alcohol consumption | 2.16 (0.49–9.42) | 0.308 | |
| None of them | Reference | ||
| Both of them | 10.34 (2.00–53.57) | 0.005 | |
| ONFH stage | 2 or 3 (before osteoarthrosis) | 0.51 (0.20–1.30) | 0.161 |
| 4 (osteoarthrosis) | Reference | ||
| Previous hip surgery in index joint | No | Reference | |
| Yes | 0.98 (0.30–3.18) | 0.976 | |
| Surgical approach | Posterior | 0.77 (0.32–1.81 | 0.546 |
| Anterior or anterolateral | UC1 | 0.974 | |
| Lateral | Reference | ||
| Incision length | Conventional | Reference | |
| MIS | 5.07 (2.07–12.39) | <0.001 | |
| New type of BPs (nBPs) or others (oBPs) | nBPs | Reference | |
| oBPs | 0.83 (0.46–1.51) | 0.551 | |
| Surface of prosthetic neck: smooth (sBPs) or rough (rBPs) | sBPs | Reference | |
| rBPs | 1.40 (0.75–2.60) | 0.292 | |
| Outer surface of outer head: alumina ceramic (aBPs) or metal (mBPs) | aBPs | 2.17 (1.20–3.92) | 0.010 |
| mBPs | Reference | ||
| Inner articulating surface of outer head: HXLPE (hBPs) or cPE (cBPs) | hBPs | Reference | |
| cBPs | 0.56 (0.24–1.35) | 0.200 | |
| Femoral component fixation | Uncemented | Reference | |
| Cemented | 0.94 (0.29–3.03) | 0.911 | |
| Surface finish of femoral stem | Grid blast (for bone on growth) | Reference | |
| Porous with/without coating | 0.57 (0.14–2.37) | 0.435 | |
| Cement with/without polish | 0.66 (0.11–3.98) | 0.653 | |
| Others | 0.16 (0.01–1.78) | 0.135 | |
| Material of inner head | Metal | Reference | |
| Ceramic | 1.63 (0.91–2.92) | 0.101 | |
| Inner head diameter | 32 mm | UC2 | 0.975 |
| 28 mm | 0.80 (0.33–1.96) | 0.630 | |
| 26 mm | 1.20 (0.62–2.31) | 0.597 | |
| 22 mm | Reference |
BPs: bipolar hemiarthroplasties. ONFH: osteonecrosis of the femoral head. CI: confidence interval. BMI: body mass index. UC1: unable to calculate because no case needed reoperation in the 17 BPs performed with an anterior or anterolateral approach. MIS: minimum-incision surgery. HXLPE: highly (approximately 10 Mrad) cross-linked polyethylene. cPE: conventional polyethylene. UC2: unable to calculate because no case needed reoperation in the 5 BPs with a 32 mm inner head.
Table 6.
Multivariate analysis applying the COX proportional-hazard model to the 886 BPs performed for ONFH.
Table 6.
Multivariate analysis applying the COX proportional-hazard model to the 886 BPs performed for ONFH.
| Variable | Factor | Hazard Ratio (95% CI) | p-Value |
|---|---|---|---|
| ONFH-associated factor | Systemic steroid use | 1.98 (0.47–8.40) | 0.354 |
| Excessive alcohol consumption | 2.14 (0.49–9.39) | 0.311 | |
| None of them | Reference | ||
| Both of them | 9.13 (1.76–47.33) | 0.008 | |
| Incision length | Conventional | Reference | |
| MIS | 5.61 (2.25–13.97) | <0.001 | |
| Outer surface of outer head | Alumina ceramic (aBPs) | 2.40 (1.32–4.38) | 0.004 |
| Metal (mBPs) | Reference |
BPs: bipolar hemiarthroplasties. ONFH: osteonecrosis of the femoral head. CI: confidence interval. MIS: minimum-incision surgery. aBPs: BPs with an alumina outer head. mBPs: BPs with a metal outer head.
Table 7.
Reasons for need for reoperation regarding the materials of the outer surface of the outer head in the 886 BPs performed for ONFH.
Table 7.
Reasons for need for reoperation regarding the materials of the outer surface of the outer head in the 886 BPs performed for ONFH.
| Reasons for Need for Reoperation (n) | mBP (648) | aBP (238) | Total (886) |
|---|---|---|---|
| Proximal migration of the outer head | 17 | 13 | 30 |
| Pain | 5 | 2 | 7 |
| Others (n ≤ 3 for each) | 5 | 5 | 10 |
| Total (%) | 27 (4.2%) | 20 (8.4%) | 47 (5.3%) |
BPs: bipolar hemiarthroplasty. ONFH: osteonecrosis of the femoral head. mBP: BP with a metal outer head. aBP: BP with an alumina outer head.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Kobayashi, S.; Sugano, N.; Ando, W.; Fukushima, W.; Kondo, K.; Sakai, T. Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head. Materials 2025, 18, 2125. https://doi.org/10.3390/ma18092125
AMA Style
Kobayashi S, Sugano N, Ando W, Fukushima W, Kondo K, Sakai T. Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head. Materials. 2025; 18(9):2125. https://doi.org/10.3390/ma18092125
Chicago/Turabian StyleKobayashi, Seneki, Nobuhiko Sugano, Wataru Ando, Wakaba Fukushima, Kyoko Kondo, and Takashi Sakai. 2025. "Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head" Materials 18, no. 9: 2125. https://doi.org/10.3390/ma18092125
APA StyleKobayashi, S., Sugano, N., Ando, W., Fukushima, W., Kondo, K., & Sakai, T. (2025). Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head. Materials, 18(9), 2125. https://doi.org/10.3390/ma18092125
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
