- Email: [email protected]
Nonmodular Stems Are a Viable Alternative to Modular Stems in Revision Total Hip Arthroplasty
The Journal of Arthroplasty 34 (2019) S292eS296
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Revision Arthroplasty
Nonmodular Stems Are a Viable Alternative to Modular Stems in Revision Total Hip Arthroplasty Andrew J. Clair, MD *, Zlatan Cizmic, MD, Jonathan M. Vigdorchik, MD, Lazaros A. Poultsides, MD, MSc, PhD, Ran Schwarzkopf, MD, MSc, Parthiv A. Rathod, MD, Ajit J. Deshmukh, MD Department of Orthopaedic Surgery, NYU Langone Medical Center, NYU Langone Orthopedic Hospital, New York, NY
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 December 2018 Received in revised form 1 March 2019 Accepted 2 March 2019 Available online 19 March 2019
Background: Nonmodular and modular femoral stems have been associated with complications after revision total hip arthroplasty (rTHA). As such, the ideal femoral component for rTHA remains undecided. This study aims to report outcomes of titanium, tapered-fluted, modular and nonmodular femoral components in rTHA. Methods: From January 1, 2013 to September 30, 2017, all rTHAs using modular or nonmodular femoral stems were identified. Demographic data including age, gender, and American Society of Anesthesiologists scores were collected. Surgical details including operative time and implant cost were also collected. Clinical outcomes including length of stay, dislocation, infection, fracture, reoperation, and rerevision were collected. Statistical analysis was performed using chi-square test and Student's t-test for all categorical and continuous variables, respectively. Results: One hundred forty-six rTHA cases (103 modular and 43 nonmodular) were identified with an average follow-up of 29 months (range 3-59 months). Nonmodular stems had a significantly lower cost when compared to modular implants (modular stems 120.8% higher cost; P < .001). The surgical time of nonmodular components was significantly greater (193 minutes vs 163 minutes; P ¼ .029). There were no differences observed in any other surgical details or clinical outcomes assessed, including length of stay (P ¼ .323), rate of re-revision of the femoral implant (P ¼ .389), rate of re-operation (P ¼ .383), and postop complications (P ¼ .241), including infection (P ¼ .095), dislocation (P ¼ .778), and fracture (P ¼ .959). Conclusions: Nonmodular components provide encouraging clinical results with significantly lower costs compared to modular implants in rTHA. The use of titanium, tapered-fluted, nonmodular components may offer a more cost-effective approach to rTHA compared to their modular counterparts. © 2019 Elsevier Inc. All rights reserved.
Keywords: femoral revisions revision total hip arthroplasty hip arthroplasty complications tapered modular stems tapered nonmodular stems tapered monobloc stems
With the demand for primary total hip arthroplasties (THAs) expected to increase by 174% by 2030, the up-trending demand for revision hip procedures is expected to follow suit with estimates of demand doubling by 2026 [1]. This is especially true with the increased demand in primary THA and a younger patient population undergoing total joint arthroplasty (TJA). Revision total hip arthroplasty (rTHA) currently accounts for nearly 15% of the hip
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 https://doi.org/10.1016/j.arth.2019.03.007. * Reprint requests: Andrew J. Clair, MD, Department of Orthopaedic Surgery, NYU Langone Medical Center, NYU Langone Orthopedic Hospital, 301 East 17th Street, New York, NY 10003. https://doi.org/10.1016/j.arth.2019.03.007 0883-5403/© 2019 Elsevier Inc. All rights reserved.
arthroplasty procedures performed in the United States [2]. As the demand for THA and rTHA continues to expand, providing quality care at the best value is paramount. This consideration is especially important as the reimbursement landscape in adult reconstruction shifts toward bundled payment reimbursement. Femoral component revision in rTHA is technically challenging, especially in the presence of substantial bone loss affecting the proximal femur. Although cylindrical, fully coated, cobalt-chromium nonmodular stems have shown excellent 10-year survivorship of >88% [3e6], there is concern regarding reported postoperative thigh pain and severe femoral stress shielding [5e7]. The development of tapered fluted titanium (TFT) implants has largely mitigated these concerns. Originally designed by Wagner in the 1980s [8,9], the implant is designed to engage the diaphyseal cortex, with axial stability achieved by driving the tapered region of the stem through
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
a conically reamed femoral diaphysis and rotational stability achieved by longitudinal spines along the implant [10]. With both nonmodular and modular TFT stem options, modularity initially gained popularity in North America with several studies reporting promising results [10e14]. However, concerns regarding modular TFT implants developed after several reports of catastrophic failure due to junctional fractures of the implants [15e17]. Nonmodular TFT implants have provided potential for similarly successful outcomes without this risk, at a potentially reduced cost. This study aims to review the short-term to midterm results of rTHA at a single urban orthopedic specialty hospital within a tertiary academic medical center. We hypothesized that modular and nonmodular TFT implants in rTHA would have no difference in clinical outcomes with an opportunity for significant cost savings realized in the nonmodular implants (Fig. 1). Materials and Methods Patient Selection This retrospective observational cohort study was conducted at a single urban tertiary academic medical center. Institutional review board approval was obtained before chart review and data analysis of our institution’s electronic medical records. Between January 2013 and September 2017, all rTHAs of femoral components using modular or nonmodular femoral TFT stems were identified from an institutional, prospectively collected database. All rTHAs requiring exchange of the femoral component were included, including periprosthetic infection. Conversion THAs, rTHAs not using TFT stems, rTHAs with less than 3 months of follow-up, and rTHAs that did not undergo femoral revision were excluded. The final cohort was divided into 2 groups: modular or nonmodular. Data Collection Combined qualitative data collected for the 2 groups included demographic and baseline variables (eg age at surgery, gender, American Society of Anesthesiologists scores, length of stay, and Paprosky classification of bone loss [18]), and intraoperative details
S293
including total operative time, intraoperative complications, length of implant, and implant cost. Two authors reviewed all preoperative radiographs to assess the femoral Paprosky classification. Any discrepancies between the reviewers were discussed, and a consensus was made. Total operative time was defined as the length of time between initial incision and incision closure. Postoperative clinical outcomes were examined through chart review for complications including dislocation, infection, fracture, leg length inequality, and venous thromboembolism (VTE). Also included in this analysis was whether or not these complications resulted in the need for reoperation without a stem revision or a rerevision. Statistical Analysis Baseline and demographic characteristics were summarized by standard descriptive summaries. All data were managed using Excel software (Microsoft Corporation, Richmond, WA). Independent sample t-tests were used to compare continuous variables, whereas a chi-squared analysis was performed to compare categorical variables. All statistical analyses were performed using SPSS, version 23, Statistics software (International Business Machines Inc., Armonk, NY). A P-value of <0.05 was established as the cutoff for determining statistical significance. Results Demographics and Baseline Characteristics A total of 146 rTHAs (43 nonmodular and 103 modular) were performed by 22 different surgeons with an average follow-up of 8.4 months in the nonmodular cohort (range 3-23 months) and 21.5 months in the modular cohort (range 3.5-59 months). All patients who met inclusion criteria were included in the analysis (Table 1). A list of implanted nonmodular and modular femoral stems and the indications for rTHA in each cohort are listed in Tables 2 and 3. Of the total cohort, 25.2% of the rTHAs were secondary to periprosthetic joint infection. There was no difference appreciated between the nonmodular cohort and modular cohort (30.2% and
Fig. 1. Nonmodular (left) and modular (right) revision total hip arthroplasty implants.
S294
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
Table 1 Demographics and Baseline Characteristics.
Table 3 Indications for Revision Total Hip Arthroplasty.
Demographics
Nonmodular
Modular
P Value
Age, y (±SD) Gender Female Male ASA score I II III IV N/A Length of stay, d (±SD) Paprosky classification I II IIIA IIIB Surgical time, min (±SD) Implant cost, dollars (±SD)
66 (11)
65 (11)
0.461
25 18
54 49
0.528
0 13 25 2 3 4.8 (2.6)
4 61 30 4 4 4.32 (3.0)
0.007
5 19 12 7 193.2 (66.2) 5549 (885)
30 44 17 12 163.3 (77.7) 6703 (670)
Indication for Revision
Nonmodular
Modular
Fracture Dislocation or instability Loosening Infection THA conversion Implant fracture Trunionosis or metallosis or pseudotumor
25.6% 9.3% 23.3% 30.2% 4.7% 4.7% 2.3%
16.5% 3.9% 49.5% 22.3% 1.9% 1.0% 4.8%
THA, total hip arthroplasty. 0.323 0.124
0.029 <0.001
ASA, American Society of Anesthesiologists; SD, standard deviation.
22.3%, P ¼ .639). The main reasons for revisions in the nonmodular cohort included infection (30.2%), periprosthetic fracture (25.6%), and aseptic loosening (23.3%). The main reasons for revisions in the modular cohort included aseptic loosening (49.5%), infection (22.3%), and periprosthetic fracture (16.5%). Modular stems were significantly more expensive than nonmodular stems (modular stems 120.8% higher cost; P < .001). All demographic patient data were found to be similar except for significantly higher American Society of Anesthesiologists scores in the modular cohort (P ¼ .007). Total surgical time was found to be significantly greater (193 ± 66 minutes vs 163 ± 78 minutes; P ¼ .029) with nonmodular stems compared to modular stems. There were no differences observed between the groups with regards to gender, age, Paprosky femoral classification, and length of stay (Table 1).
Complications There was a total of 28 complications, 11 (25.6%) in the nonmodular cohort vs 17 (16.5%) in the modular cohort, (P ¼ .204) with no difference between the 2 cohorts (Table 4). The nonmodular cohort had 7 patients experience periprosthetic joint infections, 3 patients with dislocation or instability, and 2 patients had periprosthetic femur fractures (1 intraoperative and 1 postoperative). Of these complications, 4 required a reoperation without a revision of the stem, all for infection (3 irrigation and debridement with head and liner exchange, 1 debridement, antibiotics, and implant retention). Four required a re-revision of the femoral stem implant (3 for infection and 1 for dislocation). The modular cohort had 7 patients experience periprosthetic joint infections, 6 patients had dislocation or instability, 5 patients sustained periprosthetic femur fractures, and 1 superficial infection (1 patient experienced an
infection, dislocation, and a fracture). Of these complications, 7 required a reoperation without a revision to the stem (4 for infection, 1 for fracture, 1 for dislocation, 1 for an acetabular revision, 1 for open reduction internal fixation of a femur fracture) and 4 required a re-revision of the femoral stem implant (3 for infection, 1 for dislocation). There were no documented re-revisions for implant failures, subsidence, aseptic loosening, or junctional fractures in this cohort. Overall, the survivorship of the nonmodular cohort was 90.7% at a mean of 8.4 months (range, 3-23 months). Although a complication of any kind was reported in 11 of 43 (25.6%), ultimately only 4 of 43 (9.3%) patients went on to have re-revision of the stem. In the modular cohort of this study, the survivorship was found to be 94.2% at a mean of 21.5 months (range, 3.5-59 months) with 6 of 103 patients undergoing re-revision of the stem. Discussion Surgical treatment of femoral bone loss in rTHA is a particularly difficult problem in the management of failed hip arthroplasty [18e20]. Implant selection is a critical component of the preoperative planning algorithm in these cases. Diaphyseal fixation is paramount in this patient population, and the development of TFT stems have shown promise [11,21]. Opting for modular implants, that help achieve appropriate leg length, offset and version, in these challenging patients often provides the orthopedic surgeon an advantage when the bone loss is severe or the proximal femur is abnormally shaped. However, the undue risk of catastrophic failure with several reports of implant junctional fractures in modular implants, at time points ranging from 13 months to 10 years, due to fretting corrosion [16,17,22] has allowed nonmodular implants to gain traction in the arthroplasty community. This study elicited no significant difference in the short-term clinical outcomes of modular TFT stems vs nonmodular TFT stems in rTHA. With significant implant cost savings realized in the nonmodular cohort, the use of nonmodular TFT implants presents an opportunity to improve value without compromising safety and quality. The findings of this study help to illustrate that a reliably consistent femoral implant can be utilized for rTHA without incurring the risk of a modular junction and at a significant discounted price compared to a modular implant. While we explored
Table 4 Complications.
Table 2 List of Nonmodular and Modular Revision Implants. Nonmodular
Modular
Smith & Nephew Redapt (London, United Kingdom) Zimmer Wagner SL Revision (Warsaw, Indiana) Encore Medical LIMA hip (Austin, Texas)
Stryker Restoration Modular (Kalamazoo, Michigan) Zimmer ZMR Taper Revision (Warsaw, Indiana)
Total complications, (%) Infection, (%) Dislocation, (%) Fracture, (%) Re-revision, (%) Reoperation, (%)
Nonmodular
Modular
P Value
11 7 3 2 4 4
17 7 6 5 4 7
0.204 0.076 0.792 0.958 0.190 0.601
(25.6%) (16.3) (7.0) (4.7) (9.3) (9.3)
(16.5%) (6.8) (4.2) (3.5) (3.9) (6.8)
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
the short-term to midterm results of these implants, further research efforts will be required to explore patient outcomes in the long term. The minimum 3-month follow-up in this study was selected to include the typical 90-day window of a bundled payment. Although there was no statistically significant difference appreciated in the infection rates of the 2 implants, it was interesting to find that the rate of infection in the nonmodular implants (16.3%) was higher than that of the modular implants (6.8%). The reason for this finding is not clear; however, it is possible that this could be related to increased operative time. We appreciated a significant difference in operative time between the 2 implants with the nonmodular cohort averaging approximately 30 minutes longer per case (193 ± 66 minutes vs 163 ± 78 minutes; P ¼ .029). The reason for this discrepancy is also not entirely clear, however, as the nature of each revision is different, this difference may not be attributable to the implants but to the variability in the revision surgeries being performed. Although we appreciated no significant difference in Paprosky classification between the 2 cohorts, there still may be a wide range of variability in rTHA complexity. In addition, this study of femoral implants included rTHAs, regardless of whether or not the cup was revised as well. Most of the literature regarding complications in the setting of increased operative time in TJA is in regard to primary TJA. This is likely due to the complex and variable nature of revision surgery, as comparing the operative time of 2 different operations for different indications may not be appropriate. However, Bohl et al [23] appreciated a 9% increase in the risk of surgical site infection with just a 15-minute increase in the operative time in primary TJA. From financial perspective, the findings of this study are also quite important. With the current shift in health-care reimbursement toward a bundled payment, value-based care model, it is becoming even more important for physicians to provide quality care while also being conscious of health-care costs. Primary TJA has been a major focus of bundled care payment initiatives due to high cost, increasing prevalence, and procedural homogeneity. While revision arthroplasty is not currently part of any bundled care payment initiative because it lacks the procedural homogeneity of primary joint arthroplasty, cost savings and value-based care remain critical components of physician responsibility in revision TJA. Implant cost is routinely reported on as a source of cost saving in TJA, with one report citing rTHA implants accounting for 36% of the total hospital costs [24e26]. Despite similarly successful clinical results appreciated in this review, the cost of nonmodular implants was found to be significantly lower than that of modular implants. Modularity is desirable in complex femoral revisions. Despite the classification of monobloc TFT stems as nonmodular, there is in fact an opportunity for the surgeon to curtail implants to specific patients with the modular trials used before the final nonmodular implant. This allows the orthopedic surgeon to still maintain the ability to confirm and individualize implant length, horizontal offset, and proximal version. The ability to maintain this “modularity” in a nonmodular implant makes these stems a viable alternative to modular stems in rTHA. Limitations The present study has several limitations that must be acknowledged. First, this study was conducted at a single institution with a limited group of surgeons. However, there were still 22 surgeons included in this analysis, with several surgeons displaying a preference for one type of implant. This limitation creates the possibility of a confounder. In addition, our small sample size with limited follow-up introduces the possibility of type II beta error.
S295
The fact that follow-up duration was highly variable with data that did not allow for follow-up at discrete time points for every patient also increases this possibility. While a randomized controlled trial would be an ideal means of carrying out further research on this topic, the revision nature of the surgery investigated makes this a difficult task, and thus, this study is a retrospective cross-sectional cohort study. Conclusion In rTHA, nonmodular TFT implants in lieu of modular TFT implants present an opportunity to improve value without compromising safety and quality, as this review reveals similar short-term clinical results with significantly lower costs of nonmodular implants compared to modular implants. However, with clinical outcome data suggesting equivalence with advantages and disadvantages of each option, surgeon preference and familiarity or comfortability with implants should be considered. References [1] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780e5. [2] Haynes JA, Stambough JB, Sassoon AA, Johnson SR, Clohisy JC, Nunley RM. Contemporary surgical indications and referral trends in revision total hip arthroplasty: a 10-year review. J Arthroplasty 2016;31:622e5. [3] Hamilton WG, Cashen DV, Ho H, Hopper RH, Engh CA. Extensively porouscoated stems for femoral revision: a choice for all seasons. J Arthroplasty 2007;22(Supplement):106e10. [4] Lachiewicz PF, Soileau ES. What is the survivorship of fully coated femoral components in revision hip arthroplasty? Clin Orthop Relat Res 2015;473: 549e54. [5] Thomsen PB, Jensen NJ, Kampmann J, Baek Hansen T. Revision hip arthroplasty with an extensively porous-coated stem - excellent long-term results also in severe femoral bone stock loss. Hip Int 2013;23:352e8. [6] Paprosky WG, Greidanus NV, Antoniou J. Minimum 10-year-results of extensively porous-coated stems in revision hip arthroplasty. Clin Orthop Relat Res 1999;369:230e42. [7] Moreland JR, Bernstein ML. Femoral revision hip arthroplasty with uncemented, porous-coated stems. Clin Orthop Relat Res 1995;319:141e50. [8] Wagner H. [Revision prosthesis for the hip joint in severe bone loss]. Orthopade 1987;16:295e300. [9] Wagner H. [A revision prosthesis for the hip joint]. Orthopade 1989;18: 438e53. [10] Munro JT, Garbuz DS, Masri BA, Duncan CP. Tapered fluted titanium stems in the management of Vancouver B2 and B3 periprosthetic femoral fractures. Clin Orthop Relat Res 2014;472:590e8. [11] Fink B, Urbansky K, Schuster P. Mid term results with the curved modular tapered, fluted titanium Revitan stem in revision hip replacement. Bone Joint J 2014;96-B:889e95. [12] Gutierrez Del Alamo J, Garcia-Cimbrelo E, Castellanos V, Gil-Garay E. Radiographic bone regeneration and clinical outcome with the Wagner SL revision stem: a 5-year to 12-year follow-up study. J Arthroplasty 2007;22: 515e24. [13] Sporer SM, Paprosky WG. Femoral fixation in the face of considerable bone loss: the use of modular stems. Clin Orthop Relat Res 2004;429:227e31. [14] Rodriguez JA, Deshmukh AJ, Robinson J, Cornell CN, Rasquinha VJ, Ranawat AS, et al. Reproducible fixation with a tapered, fluted, modular, titanium stem in revision hip arthroplasty at 8-15 years follow-up. J Arthroplasty 2014;29(9 Suppl):214e8. [15] Berry DJ. Femoral revision: distal fixation with fluted, tapered grit-blasted stems. J Arthroplasty 2002;17(4 Suppl 1):142e6. [16] Rueckl K, Sculco PK, Berliner J, Cross MB, Koch C, Boettner F. Fracture risk of tapered modular revision stems: a failure analysis. Arthroplast Today 2018;4:300e5. [17] Konan S, Garbuz DS, Masri BA, Duncan CP. Modular tapered titanium stems in revision arthroplasty of the hip: the Risk and Causes of Stem Fracture. Bone Joint J 2016;98-B(1 Suppl A):50e3. [18] Della Valle CJ, Paprosky WG. The femur in revision total hip arthroplasty evaluation and classification. Clin Orthop Relat Res 2004;420:55e62. [19] March GMJ, Dehghan N, Gala L, Spangehl MJ, Kim PR. Proximal femoral arthroplasty in patients undergoing revision hip arthroplasty. J Arthroplasty 2014;29:2171e4. [20] D'Antonio J, McCarthy JC, Bargar WL, Borden LS, Cappelo WN, Collis DK, et al. Classification of femoral abnormalities in total hip arthroplasty. Clin Orthop Relat Res 1993;296:133e9.
S296
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
[21] Van Houwelingen AP, Duncan CP, Masri BA, Greidanus NV, Garbuz DS. High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years followup. Clin Orthop Relat Res 2013;471:454e62. [22] Lakstein D, Eliaz N, Levi O, Backstein D, Kosashvili Y, Safir O, et al. Fracture of cementless femoral stems at the mid-stem junction in modular revision hip arthroplasty systems. J Bone Joint Surg Am 2011;93:57e65. [23] Bohl DD, Ondeck NT, Darrith B, Hannon CP, Fillingham YA, Della Valle CJ. Impact of operative time on adverse events following primary total joint arthroplasty. J Arthroplasty 2018;33:2256e62.
[24] Althausen PL, Mead L. Bundled payments for care improvement: lessons learned in the first year. J Orthop Trauma 2016;30(Suppl 5): S50e3. [25] Bosco JA, Alvarado CM, Slover JD, Iorio R, Hutzler LH. Decreasing total joint implant costs and physician specific cost variation through negotiation. J Arthroplasty 2014;29:678e80. [26] Collins KD, Chen KK, Ziegler JD, Schwarzkopf R, Bosco JA, Iorio R. Revision total hip arthroplasty-reducing hospital cost through fixed implant pricing. J Arthroplasty 2017;32:S141e3.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Revision Arthroplasty
Nonmodular Stems Are a Viable Alternative to Modular Stems in Revision Total Hip Arthroplasty Andrew J. Clair, MD *, Zlatan Cizmic, MD, Jonathan M. Vigdorchik, MD, Lazaros A. Poultsides, MD, MSc, PhD, Ran Schwarzkopf, MD, MSc, Parthiv A. Rathod, MD, Ajit J. Deshmukh, MD Department of Orthopaedic Surgery, NYU Langone Medical Center, NYU Langone Orthopedic Hospital, New York, NY
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 December 2018 Received in revised form 1 March 2019 Accepted 2 March 2019 Available online 19 March 2019
Background: Nonmodular and modular femoral stems have been associated with complications after revision total hip arthroplasty (rTHA). As such, the ideal femoral component for rTHA remains undecided. This study aims to report outcomes of titanium, tapered-fluted, modular and nonmodular femoral components in rTHA. Methods: From January 1, 2013 to September 30, 2017, all rTHAs using modular or nonmodular femoral stems were identified. Demographic data including age, gender, and American Society of Anesthesiologists scores were collected. Surgical details including operative time and implant cost were also collected. Clinical outcomes including length of stay, dislocation, infection, fracture, reoperation, and rerevision were collected. Statistical analysis was performed using chi-square test and Student's t-test for all categorical and continuous variables, respectively. Results: One hundred forty-six rTHA cases (103 modular and 43 nonmodular) were identified with an average follow-up of 29 months (range 3-59 months). Nonmodular stems had a significantly lower cost when compared to modular implants (modular stems 120.8% higher cost; P < .001). The surgical time of nonmodular components was significantly greater (193 minutes vs 163 minutes; P ¼ .029). There were no differences observed in any other surgical details or clinical outcomes assessed, including length of stay (P ¼ .323), rate of re-revision of the femoral implant (P ¼ .389), rate of re-operation (P ¼ .383), and postop complications (P ¼ .241), including infection (P ¼ .095), dislocation (P ¼ .778), and fracture (P ¼ .959). Conclusions: Nonmodular components provide encouraging clinical results with significantly lower costs compared to modular implants in rTHA. The use of titanium, tapered-fluted, nonmodular components may offer a more cost-effective approach to rTHA compared to their modular counterparts. © 2019 Elsevier Inc. All rights reserved.
Keywords: femoral revisions revision total hip arthroplasty hip arthroplasty complications tapered modular stems tapered nonmodular stems tapered monobloc stems
With the demand for primary total hip arthroplasties (THAs) expected to increase by 174% by 2030, the up-trending demand for revision hip procedures is expected to follow suit with estimates of demand doubling by 2026 [1]. This is especially true with the increased demand in primary THA and a younger patient population undergoing total joint arthroplasty (TJA). Revision total hip arthroplasty (rTHA) currently accounts for nearly 15% of the hip
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 https://doi.org/10.1016/j.arth.2019.03.007. * Reprint requests: Andrew J. Clair, MD, Department of Orthopaedic Surgery, NYU Langone Medical Center, NYU Langone Orthopedic Hospital, 301 East 17th Street, New York, NY 10003. https://doi.org/10.1016/j.arth.2019.03.007 0883-5403/© 2019 Elsevier Inc. All rights reserved.
arthroplasty procedures performed in the United States [2]. As the demand for THA and rTHA continues to expand, providing quality care at the best value is paramount. This consideration is especially important as the reimbursement landscape in adult reconstruction shifts toward bundled payment reimbursement. Femoral component revision in rTHA is technically challenging, especially in the presence of substantial bone loss affecting the proximal femur. Although cylindrical, fully coated, cobalt-chromium nonmodular stems have shown excellent 10-year survivorship of >88% [3e6], there is concern regarding reported postoperative thigh pain and severe femoral stress shielding [5e7]. The development of tapered fluted titanium (TFT) implants has largely mitigated these concerns. Originally designed by Wagner in the 1980s [8,9], the implant is designed to engage the diaphyseal cortex, with axial stability achieved by driving the tapered region of the stem through
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
a conically reamed femoral diaphysis and rotational stability achieved by longitudinal spines along the implant [10]. With both nonmodular and modular TFT stem options, modularity initially gained popularity in North America with several studies reporting promising results [10e14]. However, concerns regarding modular TFT implants developed after several reports of catastrophic failure due to junctional fractures of the implants [15e17]. Nonmodular TFT implants have provided potential for similarly successful outcomes without this risk, at a potentially reduced cost. This study aims to review the short-term to midterm results of rTHA at a single urban orthopedic specialty hospital within a tertiary academic medical center. We hypothesized that modular and nonmodular TFT implants in rTHA would have no difference in clinical outcomes with an opportunity for significant cost savings realized in the nonmodular implants (Fig. 1). Materials and Methods Patient Selection This retrospective observational cohort study was conducted at a single urban tertiary academic medical center. Institutional review board approval was obtained before chart review and data analysis of our institution’s electronic medical records. Between January 2013 and September 2017, all rTHAs of femoral components using modular or nonmodular femoral TFT stems were identified from an institutional, prospectively collected database. All rTHAs requiring exchange of the femoral component were included, including periprosthetic infection. Conversion THAs, rTHAs not using TFT stems, rTHAs with less than 3 months of follow-up, and rTHAs that did not undergo femoral revision were excluded. The final cohort was divided into 2 groups: modular or nonmodular. Data Collection Combined qualitative data collected for the 2 groups included demographic and baseline variables (eg age at surgery, gender, American Society of Anesthesiologists scores, length of stay, and Paprosky classification of bone loss [18]), and intraoperative details
S293
including total operative time, intraoperative complications, length of implant, and implant cost. Two authors reviewed all preoperative radiographs to assess the femoral Paprosky classification. Any discrepancies between the reviewers were discussed, and a consensus was made. Total operative time was defined as the length of time between initial incision and incision closure. Postoperative clinical outcomes were examined through chart review for complications including dislocation, infection, fracture, leg length inequality, and venous thromboembolism (VTE). Also included in this analysis was whether or not these complications resulted in the need for reoperation without a stem revision or a rerevision. Statistical Analysis Baseline and demographic characteristics were summarized by standard descriptive summaries. All data were managed using Excel software (Microsoft Corporation, Richmond, WA). Independent sample t-tests were used to compare continuous variables, whereas a chi-squared analysis was performed to compare categorical variables. All statistical analyses were performed using SPSS, version 23, Statistics software (International Business Machines Inc., Armonk, NY). A P-value of <0.05 was established as the cutoff for determining statistical significance. Results Demographics and Baseline Characteristics A total of 146 rTHAs (43 nonmodular and 103 modular) were performed by 22 different surgeons with an average follow-up of 8.4 months in the nonmodular cohort (range 3-23 months) and 21.5 months in the modular cohort (range 3.5-59 months). All patients who met inclusion criteria were included in the analysis (Table 1). A list of implanted nonmodular and modular femoral stems and the indications for rTHA in each cohort are listed in Tables 2 and 3. Of the total cohort, 25.2% of the rTHAs were secondary to periprosthetic joint infection. There was no difference appreciated between the nonmodular cohort and modular cohort (30.2% and
Fig. 1. Nonmodular (left) and modular (right) revision total hip arthroplasty implants.
S294
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
Table 1 Demographics and Baseline Characteristics.
Table 3 Indications for Revision Total Hip Arthroplasty.
Demographics
Nonmodular
Modular
P Value
Age, y (±SD) Gender Female Male ASA score I II III IV N/A Length of stay, d (±SD) Paprosky classification I II IIIA IIIB Surgical time, min (±SD) Implant cost, dollars (±SD)
66 (11)
65 (11)
0.461
25 18
54 49
0.528
0 13 25 2 3 4.8 (2.6)
4 61 30 4 4 4.32 (3.0)
0.007
5 19 12 7 193.2 (66.2) 5549 (885)
30 44 17 12 163.3 (77.7) 6703 (670)
Indication for Revision
Nonmodular
Modular
Fracture Dislocation or instability Loosening Infection THA conversion Implant fracture Trunionosis or metallosis or pseudotumor
25.6% 9.3% 23.3% 30.2% 4.7% 4.7% 2.3%
16.5% 3.9% 49.5% 22.3% 1.9% 1.0% 4.8%
THA, total hip arthroplasty. 0.323 0.124
0.029 <0.001
ASA, American Society of Anesthesiologists; SD, standard deviation.
22.3%, P ¼ .639). The main reasons for revisions in the nonmodular cohort included infection (30.2%), periprosthetic fracture (25.6%), and aseptic loosening (23.3%). The main reasons for revisions in the modular cohort included aseptic loosening (49.5%), infection (22.3%), and periprosthetic fracture (16.5%). Modular stems were significantly more expensive than nonmodular stems (modular stems 120.8% higher cost; P < .001). All demographic patient data were found to be similar except for significantly higher American Society of Anesthesiologists scores in the modular cohort (P ¼ .007). Total surgical time was found to be significantly greater (193 ± 66 minutes vs 163 ± 78 minutes; P ¼ .029) with nonmodular stems compared to modular stems. There were no differences observed between the groups with regards to gender, age, Paprosky femoral classification, and length of stay (Table 1).
Complications There was a total of 28 complications, 11 (25.6%) in the nonmodular cohort vs 17 (16.5%) in the modular cohort, (P ¼ .204) with no difference between the 2 cohorts (Table 4). The nonmodular cohort had 7 patients experience periprosthetic joint infections, 3 patients with dislocation or instability, and 2 patients had periprosthetic femur fractures (1 intraoperative and 1 postoperative). Of these complications, 4 required a reoperation without a revision of the stem, all for infection (3 irrigation and debridement with head and liner exchange, 1 debridement, antibiotics, and implant retention). Four required a re-revision of the femoral stem implant (3 for infection and 1 for dislocation). The modular cohort had 7 patients experience periprosthetic joint infections, 6 patients had dislocation or instability, 5 patients sustained periprosthetic femur fractures, and 1 superficial infection (1 patient experienced an
infection, dislocation, and a fracture). Of these complications, 7 required a reoperation without a revision to the stem (4 for infection, 1 for fracture, 1 for dislocation, 1 for an acetabular revision, 1 for open reduction internal fixation of a femur fracture) and 4 required a re-revision of the femoral stem implant (3 for infection, 1 for dislocation). There were no documented re-revisions for implant failures, subsidence, aseptic loosening, or junctional fractures in this cohort. Overall, the survivorship of the nonmodular cohort was 90.7% at a mean of 8.4 months (range, 3-23 months). Although a complication of any kind was reported in 11 of 43 (25.6%), ultimately only 4 of 43 (9.3%) patients went on to have re-revision of the stem. In the modular cohort of this study, the survivorship was found to be 94.2% at a mean of 21.5 months (range, 3.5-59 months) with 6 of 103 patients undergoing re-revision of the stem. Discussion Surgical treatment of femoral bone loss in rTHA is a particularly difficult problem in the management of failed hip arthroplasty [18e20]. Implant selection is a critical component of the preoperative planning algorithm in these cases. Diaphyseal fixation is paramount in this patient population, and the development of TFT stems have shown promise [11,21]. Opting for modular implants, that help achieve appropriate leg length, offset and version, in these challenging patients often provides the orthopedic surgeon an advantage when the bone loss is severe or the proximal femur is abnormally shaped. However, the undue risk of catastrophic failure with several reports of implant junctional fractures in modular implants, at time points ranging from 13 months to 10 years, due to fretting corrosion [16,17,22] has allowed nonmodular implants to gain traction in the arthroplasty community. This study elicited no significant difference in the short-term clinical outcomes of modular TFT stems vs nonmodular TFT stems in rTHA. With significant implant cost savings realized in the nonmodular cohort, the use of nonmodular TFT implants presents an opportunity to improve value without compromising safety and quality. The findings of this study help to illustrate that a reliably consistent femoral implant can be utilized for rTHA without incurring the risk of a modular junction and at a significant discounted price compared to a modular implant. While we explored
Table 4 Complications.
Table 2 List of Nonmodular and Modular Revision Implants. Nonmodular
Modular
Smith & Nephew Redapt (London, United Kingdom) Zimmer Wagner SL Revision (Warsaw, Indiana) Encore Medical LIMA hip (Austin, Texas)
Stryker Restoration Modular (Kalamazoo, Michigan) Zimmer ZMR Taper Revision (Warsaw, Indiana)
Total complications, (%) Infection, (%) Dislocation, (%) Fracture, (%) Re-revision, (%) Reoperation, (%)
Nonmodular
Modular
P Value
11 7 3 2 4 4
17 7 6 5 4 7
0.204 0.076 0.792 0.958 0.190 0.601
(25.6%) (16.3) (7.0) (4.7) (9.3) (9.3)
(16.5%) (6.8) (4.2) (3.5) (3.9) (6.8)
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
the short-term to midterm results of these implants, further research efforts will be required to explore patient outcomes in the long term. The minimum 3-month follow-up in this study was selected to include the typical 90-day window of a bundled payment. Although there was no statistically significant difference appreciated in the infection rates of the 2 implants, it was interesting to find that the rate of infection in the nonmodular implants (16.3%) was higher than that of the modular implants (6.8%). The reason for this finding is not clear; however, it is possible that this could be related to increased operative time. We appreciated a significant difference in operative time between the 2 implants with the nonmodular cohort averaging approximately 30 minutes longer per case (193 ± 66 minutes vs 163 ± 78 minutes; P ¼ .029). The reason for this discrepancy is also not entirely clear, however, as the nature of each revision is different, this difference may not be attributable to the implants but to the variability in the revision surgeries being performed. Although we appreciated no significant difference in Paprosky classification between the 2 cohorts, there still may be a wide range of variability in rTHA complexity. In addition, this study of femoral implants included rTHAs, regardless of whether or not the cup was revised as well. Most of the literature regarding complications in the setting of increased operative time in TJA is in regard to primary TJA. This is likely due to the complex and variable nature of revision surgery, as comparing the operative time of 2 different operations for different indications may not be appropriate. However, Bohl et al [23] appreciated a 9% increase in the risk of surgical site infection with just a 15-minute increase in the operative time in primary TJA. From financial perspective, the findings of this study are also quite important. With the current shift in health-care reimbursement toward a bundled payment, value-based care model, it is becoming even more important for physicians to provide quality care while also being conscious of health-care costs. Primary TJA has been a major focus of bundled care payment initiatives due to high cost, increasing prevalence, and procedural homogeneity. While revision arthroplasty is not currently part of any bundled care payment initiative because it lacks the procedural homogeneity of primary joint arthroplasty, cost savings and value-based care remain critical components of physician responsibility in revision TJA. Implant cost is routinely reported on as a source of cost saving in TJA, with one report citing rTHA implants accounting for 36% of the total hospital costs [24e26]. Despite similarly successful clinical results appreciated in this review, the cost of nonmodular implants was found to be significantly lower than that of modular implants. Modularity is desirable in complex femoral revisions. Despite the classification of monobloc TFT stems as nonmodular, there is in fact an opportunity for the surgeon to curtail implants to specific patients with the modular trials used before the final nonmodular implant. This allows the orthopedic surgeon to still maintain the ability to confirm and individualize implant length, horizontal offset, and proximal version. The ability to maintain this “modularity” in a nonmodular implant makes these stems a viable alternative to modular stems in rTHA. Limitations The present study has several limitations that must be acknowledged. First, this study was conducted at a single institution with a limited group of surgeons. However, there were still 22 surgeons included in this analysis, with several surgeons displaying a preference for one type of implant. This limitation creates the possibility of a confounder. In addition, our small sample size with limited follow-up introduces the possibility of type II beta error.
S295
The fact that follow-up duration was highly variable with data that did not allow for follow-up at discrete time points for every patient also increases this possibility. While a randomized controlled trial would be an ideal means of carrying out further research on this topic, the revision nature of the surgery investigated makes this a difficult task, and thus, this study is a retrospective cross-sectional cohort study. Conclusion In rTHA, nonmodular TFT implants in lieu of modular TFT implants present an opportunity to improve value without compromising safety and quality, as this review reveals similar short-term clinical results with significantly lower costs of nonmodular implants compared to modular implants. However, with clinical outcome data suggesting equivalence with advantages and disadvantages of each option, surgeon preference and familiarity or comfortability with implants should be considered. References [1] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780e5. [2] Haynes JA, Stambough JB, Sassoon AA, Johnson SR, Clohisy JC, Nunley RM. Contemporary surgical indications and referral trends in revision total hip arthroplasty: a 10-year review. J Arthroplasty 2016;31:622e5. [3] Hamilton WG, Cashen DV, Ho H, Hopper RH, Engh CA. Extensively porouscoated stems for femoral revision: a choice for all seasons. J Arthroplasty 2007;22(Supplement):106e10. [4] Lachiewicz PF, Soileau ES. What is the survivorship of fully coated femoral components in revision hip arthroplasty? Clin Orthop Relat Res 2015;473: 549e54. [5] Thomsen PB, Jensen NJ, Kampmann J, Baek Hansen T. Revision hip arthroplasty with an extensively porous-coated stem - excellent long-term results also in severe femoral bone stock loss. Hip Int 2013;23:352e8. [6] Paprosky WG, Greidanus NV, Antoniou J. Minimum 10-year-results of extensively porous-coated stems in revision hip arthroplasty. Clin Orthop Relat Res 1999;369:230e42. [7] Moreland JR, Bernstein ML. Femoral revision hip arthroplasty with uncemented, porous-coated stems. Clin Orthop Relat Res 1995;319:141e50. [8] Wagner H. [Revision prosthesis for the hip joint in severe bone loss]. Orthopade 1987;16:295e300. [9] Wagner H. [A revision prosthesis for the hip joint]. Orthopade 1989;18: 438e53. [10] Munro JT, Garbuz DS, Masri BA, Duncan CP. Tapered fluted titanium stems in the management of Vancouver B2 and B3 periprosthetic femoral fractures. Clin Orthop Relat Res 2014;472:590e8. [11] Fink B, Urbansky K, Schuster P. Mid term results with the curved modular tapered, fluted titanium Revitan stem in revision hip replacement. Bone Joint J 2014;96-B:889e95. [12] Gutierrez Del Alamo J, Garcia-Cimbrelo E, Castellanos V, Gil-Garay E. Radiographic bone regeneration and clinical outcome with the Wagner SL revision stem: a 5-year to 12-year follow-up study. J Arthroplasty 2007;22: 515e24. [13] Sporer SM, Paprosky WG. Femoral fixation in the face of considerable bone loss: the use of modular stems. Clin Orthop Relat Res 2004;429:227e31. [14] Rodriguez JA, Deshmukh AJ, Robinson J, Cornell CN, Rasquinha VJ, Ranawat AS, et al. Reproducible fixation with a tapered, fluted, modular, titanium stem in revision hip arthroplasty at 8-15 years follow-up. J Arthroplasty 2014;29(9 Suppl):214e8. [15] Berry DJ. Femoral revision: distal fixation with fluted, tapered grit-blasted stems. J Arthroplasty 2002;17(4 Suppl 1):142e6. [16] Rueckl K, Sculco PK, Berliner J, Cross MB, Koch C, Boettner F. Fracture risk of tapered modular revision stems: a failure analysis. Arthroplast Today 2018;4:300e5. [17] Konan S, Garbuz DS, Masri BA, Duncan CP. Modular tapered titanium stems in revision arthroplasty of the hip: the Risk and Causes of Stem Fracture. Bone Joint J 2016;98-B(1 Suppl A):50e3. [18] Della Valle CJ, Paprosky WG. The femur in revision total hip arthroplasty evaluation and classification. Clin Orthop Relat Res 2004;420:55e62. [19] March GMJ, Dehghan N, Gala L, Spangehl MJ, Kim PR. Proximal femoral arthroplasty in patients undergoing revision hip arthroplasty. J Arthroplasty 2014;29:2171e4. [20] D'Antonio J, McCarthy JC, Bargar WL, Borden LS, Cappelo WN, Collis DK, et al. Classification of femoral abnormalities in total hip arthroplasty. Clin Orthop Relat Res 1993;296:133e9.
S296
A.J. Clair et al. / The Journal of Arthroplasty 34 (2019) S292eS296
[21] Van Houwelingen AP, Duncan CP, Masri BA, Greidanus NV, Garbuz DS. High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years followup. Clin Orthop Relat Res 2013;471:454e62. [22] Lakstein D, Eliaz N, Levi O, Backstein D, Kosashvili Y, Safir O, et al. Fracture of cementless femoral stems at the mid-stem junction in modular revision hip arthroplasty systems. J Bone Joint Surg Am 2011;93:57e65. [23] Bohl DD, Ondeck NT, Darrith B, Hannon CP, Fillingham YA, Della Valle CJ. Impact of operative time on adverse events following primary total joint arthroplasty. J Arthroplasty 2018;33:2256e62.
[24] Althausen PL, Mead L. Bundled payments for care improvement: lessons learned in the first year. J Orthop Trauma 2016;30(Suppl 5): S50e3. [25] Bosco JA, Alvarado CM, Slover JD, Iorio R, Hutzler LH. Decreasing total joint implant costs and physician specific cost variation through negotiation. J Arthroplasty 2014;29:678e80. [26] Collins KD, Chen KK, Ziegler JD, Schwarzkopf R, Bosco JA, Iorio R. Revision total hip arthroplasty-reducing hospital cost through fixed implant pricing. J Arthroplasty 2017;32:S141e3.