The Journal of Arthroplasty xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty Julio J. Jauregui, MD, Samik Banerjee, MD, Jeffrey J. Cherian, DO, Randa K. Elmallah, MD, Todd P. Pierce, MD, Michael A. Mont, MD Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, Baltimore, Maryland
a r t i c l e
i n f o
Article history: Received 7 November 2014 Accepted 11 February 2015 Available online xxxx Keywords: revision hip arthroplasty total hip arthroplasty highly porous titanium acetabular cups aseptic survivorship
a b s t r a c t Titanium-based highly-porous metal cups have been introduced as a relatively new alternative for enhanced acetabular fixation during revision THA; limited number of studies have evaluated its outcomes. We aimed to assess the clinical, functional, and patient-reported outcomes following the use of new generation highlyporous titanium acetabular implants in the revision setting. Seventy-one revisions were (1:1) matched to a conventional porous-coated cohort and were followed-up clinically and radiographically for at least 2-years. Non-significant differences in overall aseptic-survivorship were found across all types of acetabular defects comparing both cohorts (P = 0.3). The overall HHS, UCLA, and SF-36 scores were similar between both cohorts. It remains to be seen if the great potential for enhanced osseointegration translates into improved long-term survivorship compared to conventional-porous devices. © 2015 Elsevier Inc. All rights reserved.
Revision acetabular surgery provides arthroplasty surgeons with multitude of challenges, including restoring the biomechanics of the hip, obtaining initial stable fixation and long-term durable implant survivorship, preserving bone stock, and reconstructing bone defects [1,2]. Over the past decade, a variety of highly porous titanium-based and tantalum-based metals of varying frictional coefficient and porosity have been introduced commercially as viable new alternatives to conventional porous devices for enhancing osseointegration and optimizing component stability during acetabular reconstructions [3]. Their interconnected open-celled dodecahedron structure provides large surface areas for bone on-growth/in-growth [4–7]. This may be especially important in revision settings where stable implant fixation becomes challenging in the presence of variable amounts of bone loss [8]. In addition to their improved frictional resistance, it is believed that their lower modulus of elasticity compared to conventional porous metals may minimize stress shielding and bone loss in the periacetabular region in the long run [9,10]. A number of early observational studies in primary and revision total hip arthroplasties have reported durable implant survivorship with porous tantalum based acetabular components in the revision
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.02.013. Reprint requests: Michael A. Mont, M.D., Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, MD 21215.
setting at short and mid-term follow-up [11–15]. However, there has been a paucity of studies reporting on the clinical, functional, and patient-reported outcomes of highly-porous titanium in revision hip arthroplasties. Therefore, in this study we aimed to evaluate the clinical, functional, and patient-reported outcomes following use of new generation of highly-porous titanium acetabular implants in the revision setting. We specifically evaluated: (1) aseptic implant survivorship; (2) Harris Hip Scores; (3) University of California Los Angeles Activity Scores; (4) SF36 scores, (5) satisfaction scores; and (6) complication rates, and compared these outcomes to a matched cohort of patients who had received conventional porous-coated acetabular prostheses. Methods The prospectively collected total joint arthroplasty database of our institution was searched to identify patients, who had undergone revision total hip arthroplasty with a highly porous titanium acetabular component, during the period January 2009 to June 2012. The inclusion criteria were: (1) patients who had either isolated acetabular revisions or revision of both femoral and acetabular components; (2) minimum follow-up of 2 years. The patients who had isolated femoral revisions or liner exchange were excluded from the analysis. A total of 71 patients were identified who underwent 71 revision acetabular reconstructions. All revision surgeries were performed by two experienced adult reconstructive surgeons (MAM and RED). The acetabular cup utilized was the Trident Tritanium multi-hole design (Stryker Orthopaedics, Mahwah, New Jersey) in all cases, while the femoral component used was Accolade TMZF (n = 13; Stryker
http://dx.doi.org/10.1016/j.arth.2015.02.013 0883-5403/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
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J.J. Jauregui et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
Orthopaedics, Mahwah, New Jersey); Accolade II (n = 4; Stryker Orthopaedics, Mahwah, New Jersey), and a Restoration Modular femoral component (n = 31; Stryker Orthopaedics, Mahwah, New Jersey). These patients were compared to a matched cohort (1:1) of patients who underwent revision arthroplasties with conventional porous acetabular cups (Trident; Stryker Orthopaedics, Mahwah, New Jersey) during an overlapping time period. Patients were matched by age (± 3 years), gender (1:1), body mass index (±3), and by the type of acetabular defect as described by Paprosky et al [16] (1:1). All revisions in both cohorts had a metal-on-highly cross-linked polyethylene liner (X3; Stryker Orthopaedics; Mahwah, New Jersey). Demographic, clinical, radiographic, and patient-reported outcomes data were reviewed from the office charts, medical records, discharge summaries, pre-operative studies, and imaging reports. Comorbidities were evaluated between cohorts to assess for any confounding variables. Patients in both cohorts were followed-up clinically and radiographically, at approximately 6 weeks, 12 weeks, 6 months, 12 months, and yearly thereafter. Functional evaluations were based on modified Harris Hip Scores (HHS), activity levels were assessed using the University of California Los Angeles (UCLA) activity ratings scale, and patient-reported physical and mental health status was evaluated using the SF-36 questionnaire. The patient-reported physical and mental health status was analyzed using SF-36 questionnaires. These scores were available for all patients pre-revision and at the time of final follow-up. In addition, during each follow-up evaluation, patients were assessed for medical and surgical complications such as superficial and deep wound infections, wound discharge, hematoma formations, deep vein thrombosis, pulmonary emboli, limb length discrepancy, nerve palsy, dislocation, and loosening. All patients had antero-posterior and frog lateral radiographs preoperatively and during their follow-up. These were reviewed by two senior authors at the time of their office visits. Pre-operatively, the acetabular defects were classified according to Paprosky et al’s classification [16]. These defects were further subcategorized in minor (type 1–2b) and major loss group (type 2c–type 3a). In the post-operative radiographs, presence of progressive radiolucent zones of 2 millimeters or more around the implant in the three radiographic zones was considered as defining radiographic criteria for aseptic loosening, as described by DeLee and Charnley [17]. There were 28 men and 43 women who had a mean age of 58 years (range, 26–78 years) with a mean BMI of 30 (range, 19–53 in the highlyporous cohort). The mean follow-up period in this cohort was 30 months (range, 24–42 months). Isolated acetabular revisions were performed in 23 patients, while the remaining 48 patients had revision of both femoral and acetabular components. There were 16 hips that had type 1 acetabular defects, 12 with type 2a defects, 14 with type 2b defects, 22 with type 2c defects, 4 with type 3a defects, and 3 with type 3b defects. The mean age of the patients in the matched cohort was 60 years (range 28–80 years) who had a mean BMI of 31 (range, 16–55, see Table 1). The mean follow-up in the conventional porous cohort was 2.7 years (range, 2–3.5 years). There were no significant differences in the
incidence of diabetes (P = 0.2), ischemic heart disease (P = 0.5), hypothyroidism (P = 0.9), and peripheral vascular disease (P = 0.8) among the two cohorts. There were no significant differences in the preoperative HHS (46 vs. 47 points; P = 0.5), UCLA scores (P = 0.06), and SF-36 mental (P = 0.07) and physical (P = 0.7) component scores. All data were extrapolated in to an Excel spreadsheet (Excel, Microsoft Corporation, Redmond, Washington) for initial tabulation and further descriptive and statistical analysis. Graph Pad Prism version 5.01 (GraphPad Software Inc., La Jolla, California), statistical software was used for the statistical calculations. Statistical comparisons between cohorts were performed using the Student’s t-test, Z-test, or the Wilcoxon signed ranked test to determine difference in means between measurements. Kaplan–Meier plots were measured for comparison of cumulative survivorship between cohorts. A p-value of less than 0.05 was considered to be significant. Results No significant differences in the overall aseptic survivorship rates were found across all types of acetabular defects in the highly-porous cohort compared to the conventional cohort (96 vs. 98.6%, respectively; P = 0.3). The three cups that failed in the highly-porous cohort failed at 14, 14, and 8 months after the revision surgery. These patients had type 2b, 2c, and 3a acetabular defects, respectively. The patient in the conventional porous cup failed 2 months after the revision surgery. Her acetabular defect was classified as a type 2c bony defect. The specific failure in each group will now be described. A 59 year-old man who had a BMI of 20 kg/m2 and rheumatoid arthritis, underwent revision THA with a highly-porous acetabular cup, due to aseptic failure and a type 2b acetabular defect. Fourteen months later, follow-up radiographs demonstrated loosening around the acetabular cup, at which time a re-revision was suggested, because of these findings with recent onset groin pain. The revision was uneventful and at 10 months follow-up the patient is doing well with a modified Harris Hip Score of 92 points. A 58 year-old woman who had a BMI of 23 kg/m2 underwent revision arthroplasty with a highly-porous cup, due to acetabular prosthesis loosening and type 2c bony defect. Fourteen months later, the patient presented with complaints of severe hip pain, and subsequently underwent re-revision arthroplasty with bone grafting for loose cup. Currently, 2 years after re-revision, she is doing well, and able to perform activities of daily living without pain, with a modified Harris Hip Score of 88 points. A 55 year-old man who had a BMI of 27 kg/m2, underwent revision arthroplasty with a highly porous cup due to a femoral neck fracture and a type 3a acetabular defect after resurfacing hip arthroplasty three years prior. The patient underwent re-revision arthroplasty 8 months later due to acetabular fixation failure. He subsequently developed an infection two years after re-revision that required multiple irrigation and debridement, but is currently doing well at 1-year follow-up with a modified Harris Hip Score of 83 points. A conventional cup revision was performed on a 49 year-old woman who had a BMI of 35 kg/m2 that due to acetabular osteolysis (type 2c defect). Two months
Table 1 Demographic Characteristics. Demographic Characteristics
Gender (proportion of men) BMI in kg/m2 (range) Age in years (range) Paprosky et al [16]
Type 1 defects (n) Type 2a defects (n) Type 2b defects (n) Type 2c defects (n) Type 3a defects (n) Type 3b defects (n)
Matched Cohort Conventional Porous Cups (Trident)
Study Cohort Highly Porous Cups (Tritanium)
P-Value
39% 31 (16–55) 60 (28–80) 16 12 14 22 4 3
39% 30 (19–53) 58 (26–78) 16 12 14 22 4 3
1 0.58 0.34 1 1 1 1 1 1
BMI, body mass index.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
J.J. Jauregui et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
following revision arthroplasty, she required re-revision due to acetabular cup migration and protrusio. At her latest follow-up, she reports that she is satisfied with her procedure, however is limited in activities of daily living related to alternate joint problems. In addition, the majority of the metrics measured to evaluate the post-operative outcomes showed significant improvement in the highly porous cups across all acetabular types. The modified HHS increased from a pre-operative mean of 46 to a post-operative mean of 87 points (P b 0.0001), the UCLA scores improved from 4 to 5 (P = 0.004), and the SF-36 physical component increased from 34 to 38 (P = 0.001). However, there was no significant difference between pre-operative and post-operative SF-36 mental scores (48 vs. 49, P = 0.8). Similarly, when evaluating the improvements in the conventional porous cohort, the modified HHS significantly improved from a mean of 47 to a mean post-operative score of 89 points (P b 0.0001), the UCLA also improved from 4 to 5 (P = 0.001), and the physical component from the SF-36 increased from 33 to 39 points at latest follow-up (P = 0.001). The mental component did not have a significant change (P = 0.6). Please see Table 2 for visual representation of results. Furthermore, the overall post-operative HHS (87 vs. 89 points; P = 0.5), UCLA scores (P = 0.2), SF-36 physical (P = 0.1) and mental (P = 0.5) component scores were found to be similar between the two comparison cohorts. Also, in the minor bone loss group there were no significant differences in the HHS (89 vs. 91 points; P = 0.7), UCLA scores (4.8 vs. 5.2 points; P = 0.5), SF-36 physical (39 vs. 41 points; P = 0.4), SF-36 mental (51 vs. 48 points; P = 0.4), and satisfaction rates (11 vs. 12 points; P = 0.5) among the two comparison cohorts at the time of mean final follow-up of approximately 30 months. Please see Table 3. Similarly, in the major bone loss group there were no significant differences in the HHS (84 vs. 87 points; P = 0.4), UCLA scores (3.3 vs. 4 points; P = 0.1), SF-36 physical (35 vs. 37 points; P = 0.5) and mental (45 vs. 48 points; P = 0.6) component scores, and satisfaction rates (10.9 vs. 11.2 points; P = 0.9). See Table 4. Discussion Highly-porous metals have recently been introduced commercially as an alternative to conventional porous devices in order to enhance osseointegration and optimize stability, which is of critical importance during acetabular revision surgery. However, there is a paucity of studies reporting the clinical, functional, and patient-reported outcomes of highly-porous metals in revision hip arthroplasties. We found no significant differences between the highly-porous titanium acetabular shell and the conventional porous acetabular shell in all measured outcomes. This study has several limitations. We had a small cohort of patients with only short-term follow-up. However, only a small cohort of patients is available for observation due to the recent introduction of these highly porous titanium implants. Moreover, no long-term data are available at this point. Additionally, two experienced adult reconstruction surgeons from a single high-volume center performed all revisions. Thus, the outcomes may not be generalized to other centers with lower volumes. However, we believe that this study is of highly importance in the current literature as this is the first study to our knowledge
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Table 3 Post-Operative Outcomes for the Minor Bone Loss Group. Minor Bone Loss (Paprosky et al [16] 1–2a)
HHS UCLA SF-36 physical SF-36 mental Satisfaction (out of 16 points)
Conventional Porous Acetabular Cups
Highly Porous Acetabular Cups
P-Value
91 5.2 41 48 12
89 4.8 39 51 11
0.7 0.5 0.4 0.4 0.5
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
that has compared the clinical, functional and patient-reported outcomes between highly-porous and conventional porous components in the revision setting. The results of this study are in agreement with previous studies that have investigated the outcomes in highly porous acetabular cups following revision hip arthroplasty. Jafari et al [18] retrospectively reviewed (n = 283; 295 hips) patients who underwent cementless revision hip arthroplasty with either a hydroxyapatite (HA) coated titanium cup (n = 207; 214 hips) or a highly porous tantalum cup (n = 79; 81 hips) with a minimum follow-up of two years. The authors concluded that there were no significant differences in the mechanical failure rate between the two fixation systems in both the minor and major bone deficiency groups (P = 0.85 and P = 0.27, respectively). This is the only level III study that has compared the highly porous cups with a cohort of conventional porous cups in the revision setting. Similarly, Unger et al [19] evaluated highly porous metal used in revision total hip arthroplasty (n = 59; 59 hips) with a mean follow-up of 42 months. Patients had their HHS evaluated pre-operatively, immediately post-operatively, and at two-year or most recent follow-up. Even though they had no comparison cohort, the authors concluded that this highly porous metal technology provided a functional alternative to conventional porous cups, presenting mean HHS of 74.8 (range, 33–95) pre-operatively and 94.4 (range, 58–95) post-operatively. Furthermore, Kim et al [20] followed 46 patients who underwent 46 uncemented acetabular revisions with a highly porous metal cup with a minimum follow-up of two years. The metrics used in our study are comparable to those by Kim et al [20] to assess clinical, functional, and patient reported outcomes. The authors evaluated the Oxford Hip Score, Western Ontario McMaster Universities (WOMAC) osteoarthritis index, and SF-12 generic health status score and found a significant post-operative improvement in all measured sub-scales (P b 0.05). Therefore, the conclusion reached by Kim et al [20] was that highly porous metal technology is a viable alternative for acetabular revision. Moreover, due to specific architectural characteristics, Kim et al [20] and Unger et al [19] both observed radiographic evidence of osseointegration with an expected increased long-term survivorship. From the economic point of view, the overall costs of these highly porous devices may be a few hundred dollars more than those of conventional porous acetabular cups. However, this may be adjusted once
Table 2 Pre-Operative and Post-Operative Results With Highly Porous and Conventional Porous Acetabular Cups in Revision Hip Arthroplasty.
Pre-operative HHS Post-operative HHS Pre-operative UCLA Post-operative UCLA Pre-operative SF-36 physical Post-operative SF-36 physical Pre-operative SF-36 mental Post-operative SF-36 mental
Highly Porous Acetabular Cups (Points)
P Value
Conventional Porous Acetabular Cups (Points)
P Value
46 87 4 5 34 38 48 49
0.0001
47 89 4 5 33 39 51 48
0.0001
0.004 0.001 0.8
0.001 0.001 0.6
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
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References
Table 4 Post-Operative Outcomes in the Major Bone Loss Group. Major Bone Loss (Paprosky et al [16] 2b–3a)
HHS UCLA SF-36 physical SF- 36 mental Satisfaction (out of 16 points)
Conventional Porous Acetabular Cups
Highly Porous Acetabular Cups
P-Value
87 4 37 48 11.2
84 3.3 35 45 10.9
0.4 0.1 0.5 0.6 0.9
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
the long-term follow-up studies are performed, since at that point, this additional cost may then be justified.
Conclusion The results of this study suggest that at an early follow-up of approximately 3 years, the overall aseptic survivorship, functional outcomes, activity levels, patient-reported health status, and satisfaction rates are comparable between the titanium-based highly porous and conventional porous devices utilized for acetabular fixation in the revision setting. With the enhanced osseointegration reported with these highly porous metals in the primary setting, it remains to be seen if the potential of these newer designs translates into more durable and better long-term survivorship in the revision setting. Once all revision hip arthroplasties currently performed have mid-term to long-term follow-up, collaborative studies with larger cohorts will help us better evaluate the potential benefit of these newer implants.
Acknowledgments This study was partially funded by an educational grant provided by Stryker Orthopaedics.
1. Noordin S, et al. Acetabular bone loss in revision total hip arthroplasty: principles and techniques. Instr Course Lect 2010;59:27. 2. Lawless BM, et al. Outcomes of isolated acetabular revision. Clin Orthop Relat Res 2010;468(2):472. 3. Pulido L, Rachala SR, Cabanela ME. Cementless acetabular revision: past, present, and future. Revision total hip arthroplasty: the acetabular side using cementless implants. Int Orthop 2011;35(2):289. 4. Hacking SA, et al. Fibrous tissue ingrowth and attachment to porous tantalum. J Biomed Mater Res 2000;52(4):631. 5. Bobyn JD, et al. Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. J Bone Joint Surg (Br) 1999;81(5):907. 6. Bobyn JD, et al. Tissue response to porous tantalum acetabular cups: a canine model. J Arthroplasty 1999;14(3):347. 7. Levine B, Della Valle CJ, Jacobs JJ. Applications of porous tantalum in total hip arthroplasty. J Am Acad Orthop Surg 2006;14(12):646. 8. Amstutz HC, et al. Revision of aseptic loose total hip arthroplasties. Clinical Orthopedics 170:21–33, 1982. Clin Orthop Relat Res 2004(420):2. 9. Matassi F, et al. Porous metal for orthopedics implants. Clin Cases Miner Bone Metab 2013;10(2):111. 10. Engh CA, Bobyn JD, Glassman AH. Porous-coated hip replacement. The factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg (Br) 1987;69(1):45. 11. Sternheim A, et al. Porous metal revision shells for management of contained acetabular bone defects at a mean follow-up of six years: a comparison between up to 50% bleeding host bone contact and more than 50% contact. J Bone Joint Surg (Br) 2012;94(2):158. 12. Skytta ET, et al. Early results of 827 trabecular metal revision shells in acetabular revision. J Arthroplasty 2011;26(3):342. 13. Ramappa M, et al. Early results of a new highly porous modular acetabular cup in revision arthroplasty. Hip Int 2009;19(3):239. 14. Fernandez-Fairen M, et al. Revision of failed total hip arthroplasty acetabular cups to porous tantalum components: a 5-year follow-up study. J Arthroplasty 2010; 25(6):865. 15. Naziri Q, et al. Excellent results of primary THA using a highly porous titanium cup. Orthopedics 2013;36(4):e390. 16. Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation. J Arthroplasty 1994;9(1):33. 17. DeLee JG, Charnley J. Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop Relat Res 1976;121:20. 18. Jafari SM, et al. Do tantalum and titanium cups show similar results in revision hip arthroplasty? Clin Orthop Relat Res 2010;468(2):459. 19. Unger AS, Lewis RJ, Gruen T. Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty: clinical and radiological results of 60 hips. J Arthroplasty 2005;20(8):1002. 20. Kim WY, et al. Porous tantalum uncemented acetabular shells in revision total hip replacement: two to four year clinical and radiographic results. Hip Int 2008;18(1):17.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty Julio J. Jauregui, MD, Samik Banerjee, MD, Jeffrey J. Cherian, DO, Randa K. Elmallah, MD, Todd P. Pierce, MD, Michael A. Mont, MD Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, Baltimore, Maryland
a r t i c l e
i n f o
Article history: Received 7 November 2014 Accepted 11 February 2015 Available online xxxx Keywords: revision hip arthroplasty total hip arthroplasty highly porous titanium acetabular cups aseptic survivorship
a b s t r a c t Titanium-based highly-porous metal cups have been introduced as a relatively new alternative for enhanced acetabular fixation during revision THA; limited number of studies have evaluated its outcomes. We aimed to assess the clinical, functional, and patient-reported outcomes following the use of new generation highlyporous titanium acetabular implants in the revision setting. Seventy-one revisions were (1:1) matched to a conventional porous-coated cohort and were followed-up clinically and radiographically for at least 2-years. Non-significant differences in overall aseptic-survivorship were found across all types of acetabular defects comparing both cohorts (P = 0.3). The overall HHS, UCLA, and SF-36 scores were similar between both cohorts. It remains to be seen if the great potential for enhanced osseointegration translates into improved long-term survivorship compared to conventional-porous devices. © 2015 Elsevier Inc. All rights reserved.
Revision acetabular surgery provides arthroplasty surgeons with multitude of challenges, including restoring the biomechanics of the hip, obtaining initial stable fixation and long-term durable implant survivorship, preserving bone stock, and reconstructing bone defects [1,2]. Over the past decade, a variety of highly porous titanium-based and tantalum-based metals of varying frictional coefficient and porosity have been introduced commercially as viable new alternatives to conventional porous devices for enhancing osseointegration and optimizing component stability during acetabular reconstructions [3]. Their interconnected open-celled dodecahedron structure provides large surface areas for bone on-growth/in-growth [4–7]. This may be especially important in revision settings where stable implant fixation becomes challenging in the presence of variable amounts of bone loss [8]. In addition to their improved frictional resistance, it is believed that their lower modulus of elasticity compared to conventional porous metals may minimize stress shielding and bone loss in the periacetabular region in the long run [9,10]. A number of early observational studies in primary and revision total hip arthroplasties have reported durable implant survivorship with porous tantalum based acetabular components in the revision
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.02.013. Reprint requests: Michael A. Mont, M.D., Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, MD 21215.
setting at short and mid-term follow-up [11–15]. However, there has been a paucity of studies reporting on the clinical, functional, and patient-reported outcomes of highly-porous titanium in revision hip arthroplasties. Therefore, in this study we aimed to evaluate the clinical, functional, and patient-reported outcomes following use of new generation of highly-porous titanium acetabular implants in the revision setting. We specifically evaluated: (1) aseptic implant survivorship; (2) Harris Hip Scores; (3) University of California Los Angeles Activity Scores; (4) SF36 scores, (5) satisfaction scores; and (6) complication rates, and compared these outcomes to a matched cohort of patients who had received conventional porous-coated acetabular prostheses. Methods The prospectively collected total joint arthroplasty database of our institution was searched to identify patients, who had undergone revision total hip arthroplasty with a highly porous titanium acetabular component, during the period January 2009 to June 2012. The inclusion criteria were: (1) patients who had either isolated acetabular revisions or revision of both femoral and acetabular components; (2) minimum follow-up of 2 years. The patients who had isolated femoral revisions or liner exchange were excluded from the analysis. A total of 71 patients were identified who underwent 71 revision acetabular reconstructions. All revision surgeries were performed by two experienced adult reconstructive surgeons (MAM and RED). The acetabular cup utilized was the Trident Tritanium multi-hole design (Stryker Orthopaedics, Mahwah, New Jersey) in all cases, while the femoral component used was Accolade TMZF (n = 13; Stryker
http://dx.doi.org/10.1016/j.arth.2015.02.013 0883-5403/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
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J.J. Jauregui et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
Orthopaedics, Mahwah, New Jersey); Accolade II (n = 4; Stryker Orthopaedics, Mahwah, New Jersey), and a Restoration Modular femoral component (n = 31; Stryker Orthopaedics, Mahwah, New Jersey). These patients were compared to a matched cohort (1:1) of patients who underwent revision arthroplasties with conventional porous acetabular cups (Trident; Stryker Orthopaedics, Mahwah, New Jersey) during an overlapping time period. Patients were matched by age (± 3 years), gender (1:1), body mass index (±3), and by the type of acetabular defect as described by Paprosky et al [16] (1:1). All revisions in both cohorts had a metal-on-highly cross-linked polyethylene liner (X3; Stryker Orthopaedics; Mahwah, New Jersey). Demographic, clinical, radiographic, and patient-reported outcomes data were reviewed from the office charts, medical records, discharge summaries, pre-operative studies, and imaging reports. Comorbidities were evaluated between cohorts to assess for any confounding variables. Patients in both cohorts were followed-up clinically and radiographically, at approximately 6 weeks, 12 weeks, 6 months, 12 months, and yearly thereafter. Functional evaluations were based on modified Harris Hip Scores (HHS), activity levels were assessed using the University of California Los Angeles (UCLA) activity ratings scale, and patient-reported physical and mental health status was evaluated using the SF-36 questionnaire. The patient-reported physical and mental health status was analyzed using SF-36 questionnaires. These scores were available for all patients pre-revision and at the time of final follow-up. In addition, during each follow-up evaluation, patients were assessed for medical and surgical complications such as superficial and deep wound infections, wound discharge, hematoma formations, deep vein thrombosis, pulmonary emboli, limb length discrepancy, nerve palsy, dislocation, and loosening. All patients had antero-posterior and frog lateral radiographs preoperatively and during their follow-up. These were reviewed by two senior authors at the time of their office visits. Pre-operatively, the acetabular defects were classified according to Paprosky et al’s classification [16]. These defects were further subcategorized in minor (type 1–2b) and major loss group (type 2c–type 3a). In the post-operative radiographs, presence of progressive radiolucent zones of 2 millimeters or more around the implant in the three radiographic zones was considered as defining radiographic criteria for aseptic loosening, as described by DeLee and Charnley [17]. There were 28 men and 43 women who had a mean age of 58 years (range, 26–78 years) with a mean BMI of 30 (range, 19–53 in the highlyporous cohort). The mean follow-up period in this cohort was 30 months (range, 24–42 months). Isolated acetabular revisions were performed in 23 patients, while the remaining 48 patients had revision of both femoral and acetabular components. There were 16 hips that had type 1 acetabular defects, 12 with type 2a defects, 14 with type 2b defects, 22 with type 2c defects, 4 with type 3a defects, and 3 with type 3b defects. The mean age of the patients in the matched cohort was 60 years (range 28–80 years) who had a mean BMI of 31 (range, 16–55, see Table 1). The mean follow-up in the conventional porous cohort was 2.7 years (range, 2–3.5 years). There were no significant differences in the
incidence of diabetes (P = 0.2), ischemic heart disease (P = 0.5), hypothyroidism (P = 0.9), and peripheral vascular disease (P = 0.8) among the two cohorts. There were no significant differences in the preoperative HHS (46 vs. 47 points; P = 0.5), UCLA scores (P = 0.06), and SF-36 mental (P = 0.07) and physical (P = 0.7) component scores. All data were extrapolated in to an Excel spreadsheet (Excel, Microsoft Corporation, Redmond, Washington) for initial tabulation and further descriptive and statistical analysis. Graph Pad Prism version 5.01 (GraphPad Software Inc., La Jolla, California), statistical software was used for the statistical calculations. Statistical comparisons between cohorts were performed using the Student’s t-test, Z-test, or the Wilcoxon signed ranked test to determine difference in means between measurements. Kaplan–Meier plots were measured for comparison of cumulative survivorship between cohorts. A p-value of less than 0.05 was considered to be significant. Results No significant differences in the overall aseptic survivorship rates were found across all types of acetabular defects in the highly-porous cohort compared to the conventional cohort (96 vs. 98.6%, respectively; P = 0.3). The three cups that failed in the highly-porous cohort failed at 14, 14, and 8 months after the revision surgery. These patients had type 2b, 2c, and 3a acetabular defects, respectively. The patient in the conventional porous cup failed 2 months after the revision surgery. Her acetabular defect was classified as a type 2c bony defect. The specific failure in each group will now be described. A 59 year-old man who had a BMI of 20 kg/m2 and rheumatoid arthritis, underwent revision THA with a highly-porous acetabular cup, due to aseptic failure and a type 2b acetabular defect. Fourteen months later, follow-up radiographs demonstrated loosening around the acetabular cup, at which time a re-revision was suggested, because of these findings with recent onset groin pain. The revision was uneventful and at 10 months follow-up the patient is doing well with a modified Harris Hip Score of 92 points. A 58 year-old woman who had a BMI of 23 kg/m2 underwent revision arthroplasty with a highly-porous cup, due to acetabular prosthesis loosening and type 2c bony defect. Fourteen months later, the patient presented with complaints of severe hip pain, and subsequently underwent re-revision arthroplasty with bone grafting for loose cup. Currently, 2 years after re-revision, she is doing well, and able to perform activities of daily living without pain, with a modified Harris Hip Score of 88 points. A 55 year-old man who had a BMI of 27 kg/m2, underwent revision arthroplasty with a highly porous cup due to a femoral neck fracture and a type 3a acetabular defect after resurfacing hip arthroplasty three years prior. The patient underwent re-revision arthroplasty 8 months later due to acetabular fixation failure. He subsequently developed an infection two years after re-revision that required multiple irrigation and debridement, but is currently doing well at 1-year follow-up with a modified Harris Hip Score of 83 points. A conventional cup revision was performed on a 49 year-old woman who had a BMI of 35 kg/m2 that due to acetabular osteolysis (type 2c defect). Two months
Table 1 Demographic Characteristics. Demographic Characteristics
Gender (proportion of men) BMI in kg/m2 (range) Age in years (range) Paprosky et al [16]
Type 1 defects (n) Type 2a defects (n) Type 2b defects (n) Type 2c defects (n) Type 3a defects (n) Type 3b defects (n)
Matched Cohort Conventional Porous Cups (Trident)
Study Cohort Highly Porous Cups (Tritanium)
P-Value
39% 31 (16–55) 60 (28–80) 16 12 14 22 4 3
39% 30 (19–53) 58 (26–78) 16 12 14 22 4 3
1 0.58 0.34 1 1 1 1 1 1
BMI, body mass index.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
J.J. Jauregui et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
following revision arthroplasty, she required re-revision due to acetabular cup migration and protrusio. At her latest follow-up, she reports that she is satisfied with her procedure, however is limited in activities of daily living related to alternate joint problems. In addition, the majority of the metrics measured to evaluate the post-operative outcomes showed significant improvement in the highly porous cups across all acetabular types. The modified HHS increased from a pre-operative mean of 46 to a post-operative mean of 87 points (P b 0.0001), the UCLA scores improved from 4 to 5 (P = 0.004), and the SF-36 physical component increased from 34 to 38 (P = 0.001). However, there was no significant difference between pre-operative and post-operative SF-36 mental scores (48 vs. 49, P = 0.8). Similarly, when evaluating the improvements in the conventional porous cohort, the modified HHS significantly improved from a mean of 47 to a mean post-operative score of 89 points (P b 0.0001), the UCLA also improved from 4 to 5 (P = 0.001), and the physical component from the SF-36 increased from 33 to 39 points at latest follow-up (P = 0.001). The mental component did not have a significant change (P = 0.6). Please see Table 2 for visual representation of results. Furthermore, the overall post-operative HHS (87 vs. 89 points; P = 0.5), UCLA scores (P = 0.2), SF-36 physical (P = 0.1) and mental (P = 0.5) component scores were found to be similar between the two comparison cohorts. Also, in the minor bone loss group there were no significant differences in the HHS (89 vs. 91 points; P = 0.7), UCLA scores (4.8 vs. 5.2 points; P = 0.5), SF-36 physical (39 vs. 41 points; P = 0.4), SF-36 mental (51 vs. 48 points; P = 0.4), and satisfaction rates (11 vs. 12 points; P = 0.5) among the two comparison cohorts at the time of mean final follow-up of approximately 30 months. Please see Table 3. Similarly, in the major bone loss group there were no significant differences in the HHS (84 vs. 87 points; P = 0.4), UCLA scores (3.3 vs. 4 points; P = 0.1), SF-36 physical (35 vs. 37 points; P = 0.5) and mental (45 vs. 48 points; P = 0.6) component scores, and satisfaction rates (10.9 vs. 11.2 points; P = 0.9). See Table 4. Discussion Highly-porous metals have recently been introduced commercially as an alternative to conventional porous devices in order to enhance osseointegration and optimize stability, which is of critical importance during acetabular revision surgery. However, there is a paucity of studies reporting the clinical, functional, and patient-reported outcomes of highly-porous metals in revision hip arthroplasties. We found no significant differences between the highly-porous titanium acetabular shell and the conventional porous acetabular shell in all measured outcomes. This study has several limitations. We had a small cohort of patients with only short-term follow-up. However, only a small cohort of patients is available for observation due to the recent introduction of these highly porous titanium implants. Moreover, no long-term data are available at this point. Additionally, two experienced adult reconstruction surgeons from a single high-volume center performed all revisions. Thus, the outcomes may not be generalized to other centers with lower volumes. However, we believe that this study is of highly importance in the current literature as this is the first study to our knowledge
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Table 3 Post-Operative Outcomes for the Minor Bone Loss Group. Minor Bone Loss (Paprosky et al [16] 1–2a)
HHS UCLA SF-36 physical SF-36 mental Satisfaction (out of 16 points)
Conventional Porous Acetabular Cups
Highly Porous Acetabular Cups
P-Value
91 5.2 41 48 12
89 4.8 39 51 11
0.7 0.5 0.4 0.4 0.5
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
that has compared the clinical, functional and patient-reported outcomes between highly-porous and conventional porous components in the revision setting. The results of this study are in agreement with previous studies that have investigated the outcomes in highly porous acetabular cups following revision hip arthroplasty. Jafari et al [18] retrospectively reviewed (n = 283; 295 hips) patients who underwent cementless revision hip arthroplasty with either a hydroxyapatite (HA) coated titanium cup (n = 207; 214 hips) or a highly porous tantalum cup (n = 79; 81 hips) with a minimum follow-up of two years. The authors concluded that there were no significant differences in the mechanical failure rate between the two fixation systems in both the minor and major bone deficiency groups (P = 0.85 and P = 0.27, respectively). This is the only level III study that has compared the highly porous cups with a cohort of conventional porous cups in the revision setting. Similarly, Unger et al [19] evaluated highly porous metal used in revision total hip arthroplasty (n = 59; 59 hips) with a mean follow-up of 42 months. Patients had their HHS evaluated pre-operatively, immediately post-operatively, and at two-year or most recent follow-up. Even though they had no comparison cohort, the authors concluded that this highly porous metal technology provided a functional alternative to conventional porous cups, presenting mean HHS of 74.8 (range, 33–95) pre-operatively and 94.4 (range, 58–95) post-operatively. Furthermore, Kim et al [20] followed 46 patients who underwent 46 uncemented acetabular revisions with a highly porous metal cup with a minimum follow-up of two years. The metrics used in our study are comparable to those by Kim et al [20] to assess clinical, functional, and patient reported outcomes. The authors evaluated the Oxford Hip Score, Western Ontario McMaster Universities (WOMAC) osteoarthritis index, and SF-12 generic health status score and found a significant post-operative improvement in all measured sub-scales (P b 0.05). Therefore, the conclusion reached by Kim et al [20] was that highly porous metal technology is a viable alternative for acetabular revision. Moreover, due to specific architectural characteristics, Kim et al [20] and Unger et al [19] both observed radiographic evidence of osseointegration with an expected increased long-term survivorship. From the economic point of view, the overall costs of these highly porous devices may be a few hundred dollars more than those of conventional porous acetabular cups. However, this may be adjusted once
Table 2 Pre-Operative and Post-Operative Results With Highly Porous and Conventional Porous Acetabular Cups in Revision Hip Arthroplasty.
Pre-operative HHS Post-operative HHS Pre-operative UCLA Post-operative UCLA Pre-operative SF-36 physical Post-operative SF-36 physical Pre-operative SF-36 mental Post-operative SF-36 mental
Highly Porous Acetabular Cups (Points)
P Value
Conventional Porous Acetabular Cups (Points)
P Value
46 87 4 5 34 38 48 49
0.0001
47 89 4 5 33 39 51 48
0.0001
0.004 0.001 0.8
0.001 0.001 0.6
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
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J.J. Jauregui et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
References
Table 4 Post-Operative Outcomes in the Major Bone Loss Group. Major Bone Loss (Paprosky et al [16] 2b–3a)
HHS UCLA SF-36 physical SF- 36 mental Satisfaction (out of 16 points)
Conventional Porous Acetabular Cups
Highly Porous Acetabular Cups
P-Value
87 4 37 48 11.2
84 3.3 35 45 10.9
0.4 0.1 0.5 0.6 0.9
HHS, Harris Hip Scores; UCLA, University of California Los Angeles Activity Score; SF-36, Short Form 36.
the long-term follow-up studies are performed, since at that point, this additional cost may then be justified.
Conclusion The results of this study suggest that at an early follow-up of approximately 3 years, the overall aseptic survivorship, functional outcomes, activity levels, patient-reported health status, and satisfaction rates are comparable between the titanium-based highly porous and conventional porous devices utilized for acetabular fixation in the revision setting. With the enhanced osseointegration reported with these highly porous metals in the primary setting, it remains to be seen if the potential of these newer designs translates into more durable and better long-term survivorship in the revision setting. Once all revision hip arthroplasties currently performed have mid-term to long-term follow-up, collaborative studies with larger cohorts will help us better evaluate the potential benefit of these newer implants.
Acknowledgments This study was partially funded by an educational grant provided by Stryker Orthopaedics.
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Please cite this article as: Jauregui JJ, et al, Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.02.013
