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Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems
The Journal of Arthroplasty xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems Philip M. Faris, MD, Merrill A. Ritter, MD , Kenneth E. Davis, MS, Hana M. Priscu Center for Hip and Knee Surgery, St. Francis Hospital, Mooresville, Indiana
a r t i c l e
i n f o
Article history: Received 15 December 2014 Accepted 27 April 2015 Available online xxxx Keywords: total knee arthroplasty AGC: Anatomical Graduated Component vanguard prosthesis prosthesis survivorship 10 year follow-up
a b s t r a c t The development of a new total knee system as a successor prosthesis in total knee arthroplasty (TKA) requires clinical outcome improvement. 10,843 TKAs were performed of which 9169 utilized the Anatomical Graduated Component (AGC) and 1674 utilized the Vanguard prosthesis (both Biomet, Warsaw, IN). Survival rates at ten years postoperatively for the AGC and Vanguard were 98.7% and 98.4% (P = .4897) respectively. The top reasons for component failure were loosening (AGC: 0.33% (86.7% tibial); Vanguard: 0.36% (66.7% tibial)), polyethylene wear, and instability. These results reveal similar outcomes in both designs, with relatively few revisions and high survival rates at ten years postoperatively. Summary: This abstract offers data concerning the usefulness of the Vanguard Total Knee System as a successor to the Anatomical Graduated Component. © 2015 Elsevier Inc. All rights reserved.
Total knee arthroplasty remains a very successful operation. Small differences exist between implant designs and most changes in implant designs have been evolutionary. These evolutionary changes have been made with the intent of developing implants with better overall function and durability. Many possible advantages have been proposed and incorporated in other designs to address concerns with TKA success in everyday use [4–8]. In an attempt to achieve these goals, an evolutionary design (Vanguard, Biomet Inc, Warsaw, IN) was developed to replace a very successful implant (AGC, Biomet Inc, Warsaw, IN) [1–3]. The evolutionary design utilized a deeper trochlear groove, more congruent coronal radius, lower posterior tibial sagittal plane radius, and a larger range of sizes while maintaining complete interchangeability of femoral and tibial components. All were done to theoretically improve patellar tracking, allow more flexion, improve polyethylene durability, and decrease medial tibial compressive loads. This study was undertaken to compare these two designs with special attention to the above parameters in a 10 year outcome model. Materials and Methods Between 1983 and 2011, 10,843 primary TKAs were performed using 9169 AGC prostheses and 1674 Vanguard prostheses, implanted
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.2015.04.042. Reprint Requests: Merrill A. Ritter, MD, The Center for Hip and Knee Surgery, St. Francis Hospital, 1199 Hadley Road, Mooresville, IN 46158.
in 5972 patients and 1209 patients respectively. Procedures using AGC prostheses were performed from September 15, 1983 to December 31, 2011 and those using Vanguard prostheses were performed from March 5, 2004 to December 31, 2011, by the same two surgeon authors, in addition to the four surgeons listed in the acknowledgements. Of the 7181 patients of this study, 61.1% were females (4390/ 7181) and had an average age and BMI of 69.2 (standard deviation (SD) = 9.2) and 31.0 (SD = 6.0), respectively. Osteoarthritis affected 96.7% of the study sample (10,489/10,843). Average follow-up was 8.7 years (±4.9) [2.0, 29.6] for the AGC group and 4.6 ± 2.0 [2.0, 10.5] for the Vanguard group. At 5 years and 10 years postoperatively, the AGC group had 6924 TKAs at 5 years and 5272 TKAs remaining at 10 years, while the Vanguard group had 790 TKAs and 86 TKAs remaining, respectively. Demographics for individual prosthesis groups are listed in Table 1. All surgeries were performed by the same group of surgeons who were also involved in the designs of both implant systems and are well acquainted with both implant designs and techniques. No learning curves were excluded from the data collection. Both posterior cruciate retaining and sacrificing designs were included in the Vanguard cohort. Variables associated with revision were analyzed by Cox's proportional hazards regression. Kaplan–Meier survivorship analysis was performed with revision of any component for any reason as the endpoint. The Wilcoxon test was used to compare early survival rates between the prostheses while the log-rank test was used to compare the later survival rates. Data used in this study were collected prospectively but were analyzed retrospectively. Postoperative conditions were additionally analyzed using Knee Society scoring for knee, function, stairs and pain scales. Beginning with the year 2002, cases for the two prostheses
http://dx.doi.org/10.1016/j.arth.2015.04.042 0883-5403/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042
2
P.M. Faris et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
Table 1 Demographic Characteristics of the AGC and Vanguard Study Groups.
No. patients No. females Age BMI Follow-up
AGC Prosthesis
Vanguard Prosthesis
5972 3653 (61.17%) 69.61 (SD = 9.11) 30.70 (SD = 5.91) 8.7 (SD = 4.9) [2.0, 29.6]
1209 737 (60.96%) 66.89 (SD = 9.19) 32.78 (SD = 6.26) 4.6 (SD = 2.0) [2.0, 10.5]
were matched based on the year of operation for clinical scores to ensure similar standards and methods.
unknown etiology. One loose femur was caused by preexisting metal sensitivity. Polywear occurred in 0.02% (2/9169) of those with AGC prostheses and 0.12(2/1,674) of those with Vanguards. One case in each group was discovered at the time of surgery but was revised due to pain of unknown etiology. Finally, instability occurred in 0.01% (1/9169) of AGCs and 0.12% (2/1674) of Vanguards. A breakdown of both sets of only component failures can be found in Table 2. Average postoperative flexion for those who received AGC prostheses was 115.0 degrees (SD = 10.8) and 114.3 degrees (SD = 12.0) at five and ten years, respectively. Average postoperative flexion for those who received Vanguard prostheses was 115.0 degrees (SD = 11.67) and 112.0 degrees (SD = 12.5) for five and ten years, respectively (P = .8978 and P = .0432 respectively).
Results Aseptic survival for those who received an AGC prosthesis was 99.4% and 98.7% at 5 and 10 years postoperatively, and for the Vanguard 99.4% at five years and 98.5% respectively (P = .4897 Wilcoxon, P = .4606 logrank). Knee, function, stair, and pain scores for each group at five and seven years postoperatively can be found in Fig. 1. The manipulation rate was 1.2% (113 of 9169) for the AGC, and 3.0% (50 of 1674) for the Vanguard, with an odds ratio of manipulation of 2.5 for the Vanguard prosthesis (OR = 2.5, P b .0001, Cochran-MantelHaenszel statistic). Without accounting for time (with survivorship calculations), the raw aseptic failure rate was 0.37% (34 of 9169) for the AGC group, and 0.60 % (10 of 1674) for the Vanguard group through 10 years postoperatively. The main reasons for revision due to component failure were loosening, polywear, and instability. For those with AGC prostheses, 30 suffered from loosening of one or more components. Of those with loosening of some sort, 26 had a loose tibial component (86.7%), two had a loose femoral component (6.7%), and two had loose patellar components (6.7%) both of which resulted in only a patella revision. There was also one case of subsidence (3.3%). Five of the procedures for loose tibias and one for a loose femur were discovered at the time of surgery but were performed for pain of unknown etiology. There were six cases of loosening of one or more components in those with Vanguard prostheses (0.60%), four of which were loose tibial components (66.7%), one of which was a loose femoral component (16.7%), and one of which was a loose patellar component (16.7%). Three of the procedures for loose tibias and one for a loose patella were discovered at the time of surgery but were performed for pain of
Discussion Although the evolutionary design of the Vanguard had specific design criteria with the intent to improve function, decrease wear, and implant loosening, there were no apparent clinical advantages found in the medium term follow-up. There also appeared to be no survival advantage, or decrease in wear or loosening. Long term comparisons are not possible due to the relatively short term use of the Vanguard. It can be said in the present study that there are no statistical advantages or disadvantages for either design. It is of interest that the modes of failure are similar, and interestingly, both groups had a relatively similar number of revisions done for pain of unknown etiology with loosening found at the time of revisions. This might imply a polymethyl methacrylate (PMMA)–metal bonding etiology. These numbers were small. Although osteolysis was not found to be a problem in either design, longer term follow-up will be needed to determine if this could be noted with the modularity of the Vanguard design. It appears that deepening the femoral trochlear did not change patellar tracking or wear. An increase in coronal radii did not seem to improve wear over the short term follow-up of the Vanguard prosthesis, nor did it alter the methods of failure. Interchangeability of poly sizes with femoral components did not change function; however, it also did not seem to increase osteolysis over the course of the study. It may well be that the survival of these implants is more related to polyethylene type than to specific design characteristics, especially in successful designs incorporating evolutionary changes. These data certainly bring forward to question of redesigning implants to replace an already successful implant.
95
Acknowledgements
85 AGC KS
75
AGC FS AGC Stairs
65
The authors would like to thank E. Michael Keating, John B. Meding, Michael E. Berend, and Robert A. Malinzak for their integral contributions of patients and surgical expertise to this study.
AGC Pain Vanguard KS
55
Vanguard FS
45
Vanguard Stairs
Reason for Revision
AGC
Vanguard
Vangaurd Pain
Loosening - Tibial - Femoral - Patellar Polywear Instability Subsidence Total
30 −26 −2 −2 2 1 1 34
6 −4 −1 −1 2 2 0 10
35 3
5
7
Table 2 Reasons for Revision Between the AGC and Vanguard Groups.
10
Years Fig. 1. Knee scores for the AGC and Vanguard prosthesis. There were n = 2351 AGCs and n = 86 Vanguards appearing for clinical evaluation at the 10-year follow-up time point.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042
P.M. Faris et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
References 1. Schroer WC, Stormont DM, Pietrzak WS, et al. Seven-year survivorship and functional outcomes of the high-flexion vanguard complete knee system. J Arthroplasty 2014;29:61. 2. Emerson RH, Higgins LL, Head WC. The AGC total knee prosthesis at average 11 years. J Arthroplasty 2000;15(4):418. 3. Ritter MA. The anatomical graduated component total knee replacement: a long-term evaluation with 20-year survival analysis. J Bone Joint Surg (Br) 2009;91(6):745. 4. Han HS, Kang SB, Yoon KS. High incidence of loosening of the femoral component in legacy posterior stabilised-flex total knee replacement. J Bone Joint Surg (Br) 2007; 89:1457.
3
5. Bauman RD, Johnson DR, Menge TJ, et al. Can a high-flexion total knee arthroplasty relieve pain and restore function without premature failure? Clin Orthop Relat Res 2012;470:150. 6. Huddleston JI, Scarborough DM, Goldvasser D, et al. How often do patients with high-flex total knee arthroplasty use high flexion? Clin Orthop Relat Res 2009;467: 1898. 7. Kievit AJ, Schafroth MU, Blankevoort L, et al. Early experience with the vanguard complete total knee system: 2–7 years of follow-up and risk factors for revision. J Arthroplasty 2014;29:348. 8. Peltola M, Malmivaara A, Paavola M. Learning curve for new technology? A nationwide register-based study of 46,363 total knee arthroplasties. J Bone Joint Surg 2013;95(23): 2097.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems Philip M. Faris, MD, Merrill A. Ritter, MD , Kenneth E. Davis, MS, Hana M. Priscu Center for Hip and Knee Surgery, St. Francis Hospital, Mooresville, Indiana
a r t i c l e
i n f o
Article history: Received 15 December 2014 Accepted 27 April 2015 Available online xxxx Keywords: total knee arthroplasty AGC: Anatomical Graduated Component vanguard prosthesis prosthesis survivorship 10 year follow-up
a b s t r a c t The development of a new total knee system as a successor prosthesis in total knee arthroplasty (TKA) requires clinical outcome improvement. 10,843 TKAs were performed of which 9169 utilized the Anatomical Graduated Component (AGC) and 1674 utilized the Vanguard prosthesis (both Biomet, Warsaw, IN). Survival rates at ten years postoperatively for the AGC and Vanguard were 98.7% and 98.4% (P = .4897) respectively. The top reasons for component failure were loosening (AGC: 0.33% (86.7% tibial); Vanguard: 0.36% (66.7% tibial)), polyethylene wear, and instability. These results reveal similar outcomes in both designs, with relatively few revisions and high survival rates at ten years postoperatively. Summary: This abstract offers data concerning the usefulness of the Vanguard Total Knee System as a successor to the Anatomical Graduated Component. © 2015 Elsevier Inc. All rights reserved.
Total knee arthroplasty remains a very successful operation. Small differences exist between implant designs and most changes in implant designs have been evolutionary. These evolutionary changes have been made with the intent of developing implants with better overall function and durability. Many possible advantages have been proposed and incorporated in other designs to address concerns with TKA success in everyday use [4–8]. In an attempt to achieve these goals, an evolutionary design (Vanguard, Biomet Inc, Warsaw, IN) was developed to replace a very successful implant (AGC, Biomet Inc, Warsaw, IN) [1–3]. The evolutionary design utilized a deeper trochlear groove, more congruent coronal radius, lower posterior tibial sagittal plane radius, and a larger range of sizes while maintaining complete interchangeability of femoral and tibial components. All were done to theoretically improve patellar tracking, allow more flexion, improve polyethylene durability, and decrease medial tibial compressive loads. This study was undertaken to compare these two designs with special attention to the above parameters in a 10 year outcome model. Materials and Methods Between 1983 and 2011, 10,843 primary TKAs were performed using 9169 AGC prostheses and 1674 Vanguard prostheses, implanted
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.2015.04.042. Reprint Requests: Merrill A. Ritter, MD, The Center for Hip and Knee Surgery, St. Francis Hospital, 1199 Hadley Road, Mooresville, IN 46158.
in 5972 patients and 1209 patients respectively. Procedures using AGC prostheses were performed from September 15, 1983 to December 31, 2011 and those using Vanguard prostheses were performed from March 5, 2004 to December 31, 2011, by the same two surgeon authors, in addition to the four surgeons listed in the acknowledgements. Of the 7181 patients of this study, 61.1% were females (4390/ 7181) and had an average age and BMI of 69.2 (standard deviation (SD) = 9.2) and 31.0 (SD = 6.0), respectively. Osteoarthritis affected 96.7% of the study sample (10,489/10,843). Average follow-up was 8.7 years (±4.9) [2.0, 29.6] for the AGC group and 4.6 ± 2.0 [2.0, 10.5] for the Vanguard group. At 5 years and 10 years postoperatively, the AGC group had 6924 TKAs at 5 years and 5272 TKAs remaining at 10 years, while the Vanguard group had 790 TKAs and 86 TKAs remaining, respectively. Demographics for individual prosthesis groups are listed in Table 1. All surgeries were performed by the same group of surgeons who were also involved in the designs of both implant systems and are well acquainted with both implant designs and techniques. No learning curves were excluded from the data collection. Both posterior cruciate retaining and sacrificing designs were included in the Vanguard cohort. Variables associated with revision were analyzed by Cox's proportional hazards regression. Kaplan–Meier survivorship analysis was performed with revision of any component for any reason as the endpoint. The Wilcoxon test was used to compare early survival rates between the prostheses while the log-rank test was used to compare the later survival rates. Data used in this study were collected prospectively but were analyzed retrospectively. Postoperative conditions were additionally analyzed using Knee Society scoring for knee, function, stairs and pain scales. Beginning with the year 2002, cases for the two prostheses
http://dx.doi.org/10.1016/j.arth.2015.04.042 0883-5403/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042
2
P.M. Faris et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
Table 1 Demographic Characteristics of the AGC and Vanguard Study Groups.
No. patients No. females Age BMI Follow-up
AGC Prosthesis
Vanguard Prosthesis
5972 3653 (61.17%) 69.61 (SD = 9.11) 30.70 (SD = 5.91) 8.7 (SD = 4.9) [2.0, 29.6]
1209 737 (60.96%) 66.89 (SD = 9.19) 32.78 (SD = 6.26) 4.6 (SD = 2.0) [2.0, 10.5]
were matched based on the year of operation for clinical scores to ensure similar standards and methods.
unknown etiology. One loose femur was caused by preexisting metal sensitivity. Polywear occurred in 0.02% (2/9169) of those with AGC prostheses and 0.12(2/1,674) of those with Vanguards. One case in each group was discovered at the time of surgery but was revised due to pain of unknown etiology. Finally, instability occurred in 0.01% (1/9169) of AGCs and 0.12% (2/1674) of Vanguards. A breakdown of both sets of only component failures can be found in Table 2. Average postoperative flexion for those who received AGC prostheses was 115.0 degrees (SD = 10.8) and 114.3 degrees (SD = 12.0) at five and ten years, respectively. Average postoperative flexion for those who received Vanguard prostheses was 115.0 degrees (SD = 11.67) and 112.0 degrees (SD = 12.5) for five and ten years, respectively (P = .8978 and P = .0432 respectively).
Results Aseptic survival for those who received an AGC prosthesis was 99.4% and 98.7% at 5 and 10 years postoperatively, and for the Vanguard 99.4% at five years and 98.5% respectively (P = .4897 Wilcoxon, P = .4606 logrank). Knee, function, stair, and pain scores for each group at five and seven years postoperatively can be found in Fig. 1. The manipulation rate was 1.2% (113 of 9169) for the AGC, and 3.0% (50 of 1674) for the Vanguard, with an odds ratio of manipulation of 2.5 for the Vanguard prosthesis (OR = 2.5, P b .0001, Cochran-MantelHaenszel statistic). Without accounting for time (with survivorship calculations), the raw aseptic failure rate was 0.37% (34 of 9169) for the AGC group, and 0.60 % (10 of 1674) for the Vanguard group through 10 years postoperatively. The main reasons for revision due to component failure were loosening, polywear, and instability. For those with AGC prostheses, 30 suffered from loosening of one or more components. Of those with loosening of some sort, 26 had a loose tibial component (86.7%), two had a loose femoral component (6.7%), and two had loose patellar components (6.7%) both of which resulted in only a patella revision. There was also one case of subsidence (3.3%). Five of the procedures for loose tibias and one for a loose femur were discovered at the time of surgery but were performed for pain of unknown etiology. There were six cases of loosening of one or more components in those with Vanguard prostheses (0.60%), four of which were loose tibial components (66.7%), one of which was a loose femoral component (16.7%), and one of which was a loose patellar component (16.7%). Three of the procedures for loose tibias and one for a loose patella were discovered at the time of surgery but were performed for pain of
Discussion Although the evolutionary design of the Vanguard had specific design criteria with the intent to improve function, decrease wear, and implant loosening, there were no apparent clinical advantages found in the medium term follow-up. There also appeared to be no survival advantage, or decrease in wear or loosening. Long term comparisons are not possible due to the relatively short term use of the Vanguard. It can be said in the present study that there are no statistical advantages or disadvantages for either design. It is of interest that the modes of failure are similar, and interestingly, both groups had a relatively similar number of revisions done for pain of unknown etiology with loosening found at the time of revisions. This might imply a polymethyl methacrylate (PMMA)–metal bonding etiology. These numbers were small. Although osteolysis was not found to be a problem in either design, longer term follow-up will be needed to determine if this could be noted with the modularity of the Vanguard design. It appears that deepening the femoral trochlear did not change patellar tracking or wear. An increase in coronal radii did not seem to improve wear over the short term follow-up of the Vanguard prosthesis, nor did it alter the methods of failure. Interchangeability of poly sizes with femoral components did not change function; however, it also did not seem to increase osteolysis over the course of the study. It may well be that the survival of these implants is more related to polyethylene type than to specific design characteristics, especially in successful designs incorporating evolutionary changes. These data certainly bring forward to question of redesigning implants to replace an already successful implant.
95
Acknowledgements
85 AGC KS
75
AGC FS AGC Stairs
65
The authors would like to thank E. Michael Keating, John B. Meding, Michael E. Berend, and Robert A. Malinzak for their integral contributions of patients and surgical expertise to this study.
AGC Pain Vanguard KS
55
Vanguard FS
45
Vanguard Stairs
Reason for Revision
AGC
Vanguard
Vangaurd Pain
Loosening - Tibial - Femoral - Patellar Polywear Instability Subsidence Total
30 −26 −2 −2 2 1 1 34
6 −4 −1 −1 2 2 0 10
35 3
5
7
Table 2 Reasons for Revision Between the AGC and Vanguard Groups.
10
Years Fig. 1. Knee scores for the AGC and Vanguard prosthesis. There were n = 2351 AGCs and n = 86 Vanguards appearing for clinical evaluation at the 10-year follow-up time point.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042
P.M. Faris et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
References 1. Schroer WC, Stormont DM, Pietrzak WS, et al. Seven-year survivorship and functional outcomes of the high-flexion vanguard complete knee system. J Arthroplasty 2014;29:61. 2. Emerson RH, Higgins LL, Head WC. The AGC total knee prosthesis at average 11 years. J Arthroplasty 2000;15(4):418. 3. Ritter MA. The anatomical graduated component total knee replacement: a long-term evaluation with 20-year survival analysis. J Bone Joint Surg (Br) 2009;91(6):745. 4. Han HS, Kang SB, Yoon KS. High incidence of loosening of the femoral component in legacy posterior stabilised-flex total knee replacement. J Bone Joint Surg (Br) 2007; 89:1457.
3
5. Bauman RD, Johnson DR, Menge TJ, et al. Can a high-flexion total knee arthroplasty relieve pain and restore function without premature failure? Clin Orthop Relat Res 2012;470:150. 6. Huddleston JI, Scarborough DM, Goldvasser D, et al. How often do patients with high-flex total knee arthroplasty use high flexion? Clin Orthop Relat Res 2009;467: 1898. 7. Kievit AJ, Schafroth MU, Blankevoort L, et al. Early experience with the vanguard complete total knee system: 2–7 years of follow-up and risk factors for revision. J Arthroplasty 2014;29:348. 8. Peltola M, Malmivaara A, Paavola M. Learning curve for new technology? A nationwide register-based study of 46,363 total knee arthroplasties. J Bone Joint Surg 2013;95(23): 2097.
Please cite this article as: Faris PM, et al, Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems, J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.04.042