Abstract
Introduction:
Contemporary outcomes of primary total hip arthroplasties (THAs) with highly cross-linked polyethylene (HXLPE) liners in patients with inflammatory arthritis have not been well studied. This study examined the implant survivorship, complications, radiographic results, and clinical outcomes of THA in patients with inflammatory arthritis.
Methods:
We identified 418 hips (350 patients) with a primary diagnosis of inflammatory arthritis who underwent primary THA with HXLPE liners from 2000 to 2017. 68% had rheumatoid arthritis, 13% ankylosing spondylitis, 7% juvenile rheumatoid arthritis, 6% psoriatic arthritis, 5% systemic lupus erythematosus, and 1% scleroderma. Mean age was 58 years, 66% were female, and mean BMI was 29 kg/m2. Uncemented femoral stems were used in 77% of cases. Uncemented acetabular components were used in all patients. Competing risk analysis was used accounting for death. Mean follow-up was 4.5 years.
Results:
The 10-year cumulative incidence of any revision was 3%, and was highest in psoriatic arthritis patients (16%). The most common indications for the 15 revisions were dislocations (8) and periprosthetic joint infections (PJI; 4, all on DMARDs). The 10-year cumulative incidence of reoperation was 6% with the most common indications being wound infections (6 cases, 4 on DMARDs) and postoperative periprosthetic femur fractures (2 cases, both uncemented stems). The 10-year cumulative incidence of complications not requiring reoperation was 13% with the most common being intraoperative periprosthetic femur fracture (15 cases, 14 uncemented stems, p=0.13). Radiographic evidence of early femoral stem subsidence was observed in 6 cases (all uncemented stems). Only 1 stem ultimately developed aseptic loosening. Harris hip scores substantially improved (p<0.001).
Conclusion:
Contemporary primary THAs with HXLPE in patients with inflammatory arthritis had excellent survivorship and good functional outcomes regardless of fixation method. Dislocation, PJI, and periprosthetic fracture were the most common complications in this contemporary inflammatory arthritis cohort.
Keywords: primary total hip arthroplasty, highly cross-linked polyethylene, rheumatoid arthritis, ankylosing spondylitis, survivorship
INTRODUCTION
Inflammatory arthritis embodies a collection of chronic autoimmune diseases that can lead to progressive and irreversible destruction of the hip1. Over the past two decades, increased utilization of disease modifying anti-rheumatic drugs (DMARDs) has been associated with a concomitant reduction in the annual number of total hip arthroplasties (THAs) performed in this population2. Despite these advancements in medical management, some patients still require THA3 and inflammatory arthritis currently remains the underlying etiology for 1–3% of primary THAs reported in clinical studies and national registries4, 5.
Outcomes following modern THA are generally excellent6.
However, data on the clinical outcomes and implant survivorship of contemporary THAs in patients with inflammatory arthritis are limited and often restricted to a single underlying etiology7. Furthermore, the optimal method of implant fixation in these patients remains controversial. Older studies support cemented femoral and acetabular components8, while more recent studies have demonstrated satisfactory results with uncemented9 or hybrid implants10 for certain diagnoses.
The purpose of this study was to examine the implant survivorship, complications, radiographic results, and clinical outcomes of contemporary primary THAs with highly cross-linked polyethylene (HXLPE) bearings in patients with inflammatory arthritis. Subgroup analyses were performed to examine implant survivorship according to underlying diagnoses and method of implant fixation as well as the relationship between DMARD use and infection-related complications.
PATIENTS AND METHODS
Following Institutional Review Board approval (ID 19–010436), ethical approval and informed consent, patients who underwent primary THA with a HXLPE liner and metal or ceramic femoral head for a primary underlying diagnosis of inflammatory arthritis from 2000 to 2017 were retrospectively identified using our institutional total joint registry. Patients with a history of previous hip surgery or concomitant diagnoses of avascular necrosis of the femoral head, native septic arthritis, post-traumatic arthritis, developmental dysplasia of the hip, and/or hip fracture were excluded. Furthermore, patients with inflammatory arthritis who underwent hemiarthroplasty, hip resurfacing, or THA with hard-on-hard bearing surfaces (e.g. metal-on-metal or ceramic-on-ceramic) or conventional PE during this period were also excluded.
With the above selection criteria, 418 hips (350 patients) were included in this study. Etiologies of inflammatory arthritis included rheumatoid arthritis (RA) in 286 hips (68%), ankylosing spondylitis (AS) in 53 hips (13%), juvenile rheumatoid arthritis (JRA) in 29 hips (7%), psoriatic arthritis (PA) in 24 hips (6%), systemic lupus erythematosus (SLE) in 23 hips (5%), and scleroderma (SC) in 3 hips (1%). Baseline demographics and operative characteristics of the study population are demonstrated in Table 1. Eight patients (2%) died within two years of index THA and 32 patients (7.6%) had less than 2 years of follow-up. For the remaining 274 patients (78%), the mean follow-up was 4.5 years (range, 2 – 18 years).
Table 1.
Baseline Characteristics
| Age (year), mean (SD) | 58 (14.8) |
| Female, No. (%) | 277 (66.3%) |
| BMI (kg/m2), mean (SD) | 29 (7) |
| Approach, No. (%) | |
| Posterolateral | 218 (52.1%) |
| Anterolateral | 133 (31.8%) |
| Direct anterior | 63 (15.1%) |
| Transtrochanteric | 4 (1%) |
| Operative Time (minutes), Median (range) | 106 (34–280) |
| Length of Stay (days), Median (range) | 3 (0–17) |
| Femoral Head Material, No. (%) | |
| Cobalt-chrome | 271 (64.8%) |
| Ceramic | 147 (35.2%) |
| Femoral Head Size, No. (%) | |
| 28 mm | 91 (21.8%) |
| 32 mm | 142 (34%) |
| ≥36 mm | 185 (44.3%) |
SD = standard deviation
Acetabular components were uncemented in all patients. Femoral components were uncemented in 320 hips (77%) and cemented in 98 hips (23%). The HXLPE liners (≥50 kGy of radiation) utilized at our institution during this time were Trilogy Longevity Crosslinked (Zimmer-Biomet; Warsaw, IN) in 135 cases (32%), Pinnacle Marathon (DePuy Synthes; Warsaw, IN) in 131 cases (31%), Pinnacle ALTRX (DePuy Synthes) in 97 cases (23%), Trident X3 (Stryker; Mahwah, NJ) in 41 cases (10%), Trident Crossfire (Stryker) in 13 cases (3%), and Reflection (Smith & Nephew; Memphis, TN) in 1 case (0.2%).
The primary outcomes investigated were implant survivorship free of any revision and survivorship free of any reoperation. Secondary outcomes included evaluation of complications, radiographic results, and clinical outcomes via Harris hip score (HHS)11. A subset analysis was performed to evaluate differences in survivorship between patients with uncemented versus hybrid constructs and among specific types of inflammatory arthritis. Finally, we examined the association of DMARD utilization and infection-related complications.
Radiographic Analysis
Radiographs were evaluated for evidence of implant loosening, osteolysis, or polyethylene wear >1 mm at latest follow-up. Radiographic analysis with a minimum of 2 views of the hip (anteroposterior and cross-table lateral) was completed for all patients by one of the authors who is a fellowship-trained orthopedic surgeon (B.M.W.). A second fellowship-trained orthopedic surgeon also was able to evaluate and concur regarding radiographic assessment (M.P.A). Fixation of cemented and uncemented femoral components was assessed by the criteria established by Harris et al.12 and Engh et al.13, respectively. Acetabular component loosening was defined as a change in cup position, cup migration >2 mm, or screw breakage14.
Statistical Methods
The data are reported as the mean and standard deviation (SD) for continuous variables that were distributed normally and median and range for continuous variables with a skewed distribution. Revision, reoperation, and complications were considered as time-to-event outcomes, and competing risks analyses were used for revision and reoperation outcomes, with death as the competing event. At least one revision or reoperation event had to have occurred within a group in order for any cumulative incidence function to be estimated. Cumulative incidence functions between groups for both outcomes were statistically compared using Gray’s Test15. As a complementary analysis, hazard ratios (HR) for implant fixation were estimated by fitting cemented and uncemented status of the femoral component as a covariate in Fine and Gray sub-distribution hazard for revision and reoperation. Furthermore, the indications for revision and reoperation were also described according to the underlying diagnosis and compared using the Fisher’s Exact Test. Survivorship free from complications that did not lead to revision or reoperation in the overall cohort was estimated using the Kaplan-Meier method16. After all complications, including both intraoperative and postoperative complications, were analyzed, Kaplan-Meier rates for only the postoperative complications were produced as well. The Fisher’s Exact Test was used to compare the risk of intraoperative periprosthetic femur fracture between cemented and uncemented femoral components. HHSs were also calculated and summarized at the preoperative timepoint as well as 3 postoperative timepoints: 2 years, 5 years, and 10 years. Differences in postoperative HHSs were compared to preoperative scores using the paired T-Test. Supplemental analyses were performed to evaluate the overall risk of periprosthetic femur fracture, dislocation, and revision for PJI. Rates of periprosthetic femur fracture were based on Kaplan-Meier survival estimates and calculated for the overall cohort and according to the method of femoral component fixation. The log-rank test was used to compare the overall periprosthetic femur fracture incidence curves between patients with cemented and uncemented femoral components. Time-to-event analyses for dislocation and revision for PJI were adjusted for death as a competing risk. In addition to the overall estimate, cumulative incidences of dislocation were also reported by surgical approach. The risk of dislocation for each surgical approach was compared via Gray’s Test. The relationship between DMARD utilization and any infection-related complication occurring within 1 and 2 years were analyzed and compared using the Fisher’s Exact Test.
RESULTS
Implant Survivorship
The overall 10-year cumulative incidence of any revision was 3.1% (95% confidence interval (CI)=1.7%, 5.8%). Of the 15 revisions, the most common indications were dislocations (8 cases) and periprosthetic joint infections (4 cases). In patients revised for dislocation, the index procedure approach was posterolateral in 5 cases (5/218) and anterolateral in 3 cases (3/133). All four patients who underwent revision for PJI were on ≥1 DMARD, but DMARD use was not associated with 2-year risk of revision for PJI (p=0.15). The remaining indications for revision included aseptic loosening of an uncemented femoral component (1), Vancouver B2 periprosthetic femur fracture (1, uncemented stem), and psoas tendon impingement (1).
The 10-year cumulative incidence of any revision was 3.1% (95% CI=1.0%, 9.5%) and 3.2% (95% CI=1.6%, 6.7%) in patients with cemented and uncemented femoral stems, respectively (p=0.64; Figure 1). There was no difference in the 10-year cumulative incidence of revision (p=0.08; Figure 2) or the causes of revision (Table 2) based on type of inflammatory arthritis.
Figure 1.
Cumulative incidence of any revision THA at 10 years by method of femoral component fixation with death as a competing risk.
Figure 2.
Cumulative incidence of any revision THA at 10 years by underlying diagnosis with death as a competing risk.
Table 2.
Causes of Revisions by Underlying Diagnosis*
| No. (%) Revisions |
||||||
|---|---|---|---|---|---|---|
| RA (n = 286) | JRA (n = 29) | PA (n = 24) | AS (n = 53) | SC (n = 3) | SLE (n = 23) | |
|
| ||||||
| Dislocation | 7 (70%) | 0 (0%) | 1 (33%) | -- | -- | -- |
| Periprosthetic joint infection | 2 (20%) | 1 (50%) | 1 (33%) | -- | -- | -- |
| Periprosthetic femur fracture | 1 (10%) | 0 (0%) | 0 (0%) | -- | -- | -- |
| Aseptic loosening | 0 (0%) | 1 (50%) | 0 (0%) | -- | -- | -- |
| Other | 0 (0%) | 0 (0%) | 1 (33%) | -- | -- | -- |
| Total no. revisions | 10 | 2 | 3 | -- | -- | -- |
RA = rheumatoid arthritis; JRA = juvenile rheumatoid arthritis; PA = psoriatic arthritis; AS = ankylosing spondylitis; SC = scleroderma; SLE = systemic lupus erythematosus
p=0.12
The overall 10-year cumulative incidence of any reoperation was 6.1% (95% CI=3.8%, 9.6%). Indications for the 9 cases that underwent reoperation without revision were delayed wound healing or superficial wound infections (6), postoperative periprosthetic femur fractures treated with open reduction and internal fixation (1 Vancouver B1 and 1 Vancouver C, both uncemented stems), and traumatic rupture of the hip abductor mechanism (1). There was no difference in the 2-year reoperation rate for any infection-related complication between patients who were on DMARDs (n = 4/248, 1.6%) and those who were not (n = 2/170, 1.2%; p=0.24).
The 10-year cumulative incidence of any reoperation was 4.1% (95% CI=1.6%, 10.9%) and 7.1% (95% CI=4.1%, 12.1%) in patients with cemented and uncemented femoral stems, respectively (p=0.31; Figure 3). The 10-year cumulative incidence of reoperation was significantly associated with type of inflammatory arthritis (p=0.02; Figure 4) although the complication that led to reoperation was not (p=0.84; Table 3).
Figure 3:
Cumulative incidence of any reoperation THA at 10 years by method of femoral component fixation with death as a competing risk.
Figure 4.
Cumulative incidence of any reoperation THA at 10 years by underlying diagnosis with death as a competing risk.
Table 3.
Causes of Reoperations by Underlying Diagnosis*
| No. (%) Reoperations |
||||||
|---|---|---|---|---|---|---|
| RA (n = 286) | JRA (n = 29) | PA (n = 24) | AS (n = 53) | SC (n = 3) | SLE (n = 23) | |
|
| ||||||
| Dislocation | 7 (44%) | 0 (0%) | 1 (25%) | 0 (0%) | 0 (0%) | -- |
| Periprosthetic joint infection^ | 4 (25%) | 1 (50%) | 2 (50%) | 0 (0%) | 1 (100%) | -- |
| Periprosthetic femur fracture | 3 (19%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | -- |
| Aseptic loosening | 0 (0%) | 1 (50%) | 0 (0%) | 0 (0%) | 0 (0%) | -- |
| Other | 2 (13%) | 0 (0%) | 1 (25%) | 1 (100%) | 0 (0%) | -- |
| Total no. reoperations | 16 | 2 | 4 | 1 | 1 | 0 |
RA = rheumatoid arthritis; JRA = juvenile rheumatoid arthritis; PA = psoriatic arthritis; AS = ankylosing spondylitis; SC = scleroderma; SLE = systemic lupus erythematosus
Superficial and deep infections
p=0.84
Complications
The 10-year cumulative incidence of complications not leading to revision or reoperation was 13.1% (95% CI=9.4%, 16.7%). The most common complication was intraoperative periprosthetic fracture (16 cases) involving the femur (15) or acetabulum (1).
The second most common complication was dislocation (9 cases). The approach was posterolateral in 6 cases (6/218), anterolateral in 2 cases (2/133), and direct anterior in 1 case (1/63). Six patients sustained more than 1 dislocation.
Nonoperative wound complications occurred in 8 patients and was not associated with DMARD use (p=0.48). Nonoperative postoperative periprosthetic femur fractures occurred in an additional 5 cases and included Vancouver AG (4) and Vancouver B1 (1) patterns.
Additional 90-day medical complications included deep vein thrombosis (4), atrial fibrillation with rapid ventricular response (4), and gastrointestinal bleed (2). One patient with atrial fibrillation also had persistent wound drainage managed conservatively.
Cumulative incidences of the three most common complications (dislocation, periprosthetic femur fracture, and PJI) were separately calculated. The 5-year cumulative incidence of any dislocation was 3.6% (95% CI=2.2%, 6.1%) and occurred similarly between patients with posterolateral, anterolateral and direct anterior approaches (p=0.66). The 10-year cumulative incidence of any periprosthetic femur fracture was 6.8% (95% CI = 3.6%, 9.9%) and was not significantly different between patients with uncemented and cemented femoral components. However, there was a clear clinical trend with 20 of 23 periprosthetic femur fractures occurring in patients with uncemented stems. The cumulative incidence of PJI was 1.0% (95% CI=0.4%, 2.7%) at 10 years.
Radiographic Results
Radiographic evidence of acetabular component loosening or surrounding osteolysis was not observed in any patient, and no patient demonstrated polyethylene wear exceeding 1 mm. Early femoral stem subsidence by a mean of 1.4 ± 1.1 cm was observed in 6 cases, and these were all uncemented. Only one stem demonstrated evidence of aseptic loosening at latest follow-up in a patient who has yet to be revised due to lack of clinical symptoms. None of these patients were revised at most recent follow-up. The remaining cemented and uncemented femoral stems appeared well-fixed at latest follow-up.
Clinical Outcomes
The HHS improved from a preoperative mean of 50 ± 14 to 90 ± 12 at 2 years (p<0.001), 91 ± 10 at 5 years (p<0.001), and 83 ± 13 at 10 years (p<0.001).
DISCUSSION
In a contemporary THA cohort with HXLPE bearings, patients with inflammatory arthritis demonstrated excellent implant survivorship, good clinical outcomes, and no bearing surface wear-related complications at mid-term follow-up, regardless of the underlying diagnosis or the method of implant fixation.
The 10-year cumulative incidences of any revision and reoperation were low, and similar between uncemented and cemented femoral fixation methods. The optimal method of fixation in this population remains controversial as the majority of available studies in the literature are difficult to extrapolate to contemporary practices due to the inclusion of older implant designs17 and dated fixation techniques18. In two separate systematic reviews, Zwartelé et al.19, 20 found no evidence to support either cemented or uncemented fixation over the other in patients with RA. Similarly, the results of our study support the selective utilization of modern uncemented or hybrid fixation techniques for primary THA in patients with various types of inflammatory arthritis.
The leading cause of revision in this study was dislocation, with a 5-year cumulative incidence of 4%, and was not related to approach (p=0.66). Patients with inflammatory arthritis have been shown to be at a significantly increased risk of dislocation after primary THA compared to patients with osteoarthritis (OA)21 and this may be related to poor soft tissue quality or other systemic health changes associated with medication regimen or the disease itself22. Regardless, inflammatory arthritis has been associated with early and late dislocation following elective primary THA23.
In this study, the overall 10-year risk of revision for PJI was low (1%), which is similar to previously reported 10-year survival free from PJI in patients with OA24. However, infection-related complications (namely wound healing issues) were the leading cause of reoperation. While some studies have reported an increased risk of PJI following primary THA in patients with inflammatory arthritis25, others have found a similar risk of PJI compared to THA performed for other diagnoses26. Perioperative utilization of DMARDs may be a potential risk factor for PJI in patients with inflammatory arthritis27 although other findings refute this28. While no significant differences were found in the risk of infection-related complications between patients who were on DMARDs and those who were not, all patients who required revision for PJI were on at least one DMARD. The similar risk of infection-related complications in this study between these groups may have been related to appropriate cessation of these medications during the perioperative period.
The underlying pathophysiology of disease and the chronic utilization of steroids and various DMARDs may affect the biomechanical properties of bone in patients with inflammatory arthritis29–31. The rate of intraoperative and postoperative periprosthetic femur fractures in this study was relatively high (7%) and occurred in patients with both cemented and uncemented femoral components (p=0.16). In contrast, the risk of aseptic loosening was low. Rud-Sorenson et al.32 found that the cumulative risk of revision due to aseptic femoral component loosening was actually lower in patients with RA (3.2%) compared to patients with OA (4.3%) at 14 years (adjusted RR = 0.54; p=0.02). The selective implant fixation methods and inclusion of only modern implants may explain the lower incidence of aseptic loosening observed in our study at mid-term follow-up.
There were limitations of this retrospective investigation. Foremost, the method of femoral implant fixation for each patient was not randomized, which could have led to differences in patient characteristics between each fixation method group. For example, younger patients with better bone quality may have been more likely to have uncemented fixation while patients with more dysmorphic proximal femurs may have been more likely to have cemented fixation. Also, while the utilization of DMARDs was determined for all patients in this study, the perioperative management of these medications, including the timing of cessation of these medications around surgery, was not able to be ascertained for all patients. Despite this limitation, the risk of infection-related complications was similar between patients who were on DMARDs and those who were not on these medications. In addition, the majority of patients in this study had RA and there were relatively fewer patients with each other type of inflammatory arthritis. Therefore, the frequency and leading causes of reoperations and revisions in the less-represented subgroups, particularly the SC group, may be different with a larger sample size. Finally, while there was no significant difference found in rates of intraoperative or postoperative periprosthetic femur fractures between cemented and uncemented stems, this could represent a Type II error, and may become significant with a larger sample size.
Contemporary primary THA with HXLPE bearings in patients with inflammatory arthritis led to excellent mid-term implant survivorship and good functional outcomes regardless of the specific type of inflammatory arthritis or the method of femoral fixation. Dislocation, PJI, and periprosthetic femur fracture were the most common complications of contemporary primary THA in this patient population. Conversely, the cumulative incidence of aseptic loosening at mid-term follow-up appears to be lower than previously reported, which may be related to improvements in modern implant designs and surgical technique. Nevertheless, given the potential for compromised soft tissue and bony integrity in this population, surgeons should consider strategies to mitigate the risk of instability and periprosthetic fracture in patients undergoing primary THA with inflammatory arthritis. In particular, surgeons should carefully assess bone quality both pre and intraoperatively, and have a low threshold to use cemented femoral fixation to help mitigate periprosthetic fracture risk. Although the association between DMARDs and infection-related complications remains unclear, the perioperative utilization of various DMARDs in patients with inflammatory arthritis should continue to be closely monitored and strategically managed given the immunosuppressive nature of these medications.
ACKNOWLEDGMENT
The authors would like to acknowledge the Andrew A. and Mary S. Sugg Professorship in Orthopedic Research for its philanthropic support that made such research possible.
Funding:
Dr. Daniel J Berry is funded by grants from the National Institutes of Health (R01AR73147, R01HL147155), NIAMS (P30AR76312). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
REFERENCES
- 1.Maynard MJ, Ranawat CS, Flynn WF Jr., Umlas ME. Total hip replacement arthroplasty in patients with inflammatory arthritis. Semin Arthroplasty. 1995. Jul;6(3):145–66. Epub 1995/06/07. [PubMed] [Google Scholar]
- 2.Cordtz RL, Hawley S, Prieto-Alhambra D, Højgaard P, Zobbe K, Overgaard S, et al. Incidence of hip and knee replacement in patients with rheumatoid arthritis following the introduction of biological DMARDs: an interrupted time-series analysis using nationwide Danish healthcare registers. Ann Rheum Dis. 2018. May;77(5):684–9. Epub 2017/12/17. [DOI] [PubMed] [Google Scholar]
- 3.Burn E, Edwards CJ, Murray DW, Silman A, Cooper C, Arden NK, et al. Lifetime risk of knee and hip replacement following a diagnosis of RA: findings from a cohort of 13 961 patients from England. Rheumatology (Oxford). 2019. Nov 1;58(11):1950–4. Epub 2019/05/28. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee, & Shoulder Arthroplasty: 2019 Annual Report Adelaide: AOA. 2019. [Google Scholar]
- 5.Mertelsmann-Voss C, Lyman S, Pan TJ, Goodman SM, Figgie MP, Mandl LA. US trends in rates of arthroplasty for inflammatory arthritis including rheumatoid arthritis, juvenile idiopathic arthritis, and spondyloarthritis. Arthritis Rheumatol. 2014. Jun;66(6):1432–9. Epub 2014/03/05. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Zak SG, Lygrisse K, Tang A, Meftah M, Long WJ, Schwarzkopf R. Primary total hip arthroplasty outcomes in octogenarians. Bone Jt Open. 2021. Jul;2(7):535–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Maric Z, Haynes RJ. Total hip arthroplasty in juvenile rheumatoid arthritis. Clin Orthop Relat Res. 1993. May(290):197–9. Epub 1993/05/01. [PubMed] [Google Scholar]
- 8.Creighton MG, Callaghan JJ, Olejniczak JP, Johnston RC. Total hip arthroplasty with cement in patients who have rheumatoid arthritis. A minimum ten-year follow-up study. J Bone Joint Surg Am. 1998. Oct;80(10):1439–46. Epub 1998/11/04. [DOI] [PubMed] [Google Scholar]
- 9.Keisu KS, Orozco F, McCallum JD 3rd, Bissett G, Hozack WJ, Sharkey PF, et al. Cementless femoral fixation in the rheumatoid patient undergoing total hip arthroplasty: minimum 5-year results. J Arthroplasty. 2001. Jun;16(4):415–21. Epub 2001/06/13. [DOI] [PubMed] [Google Scholar]
- 10.Ito H, Tanino H, Yamanaka Y, Minami A, Matsuno T. Intermediate- to long-term results after hybrid total hip arthroplasty in patients with rheumatoid arthritis. J Arthroplasty. 2013. Feb;28(2):309–14. Epub 2012/08/03. [DOI] [PubMed] [Google Scholar]
- 11.Söderman P, Malchau H. Is the Harris hip score system useful to study the outcome of total hip replacement? Clin Orthop Relat Res. 2001. Mar(384):189–97. Epub 2001/03/16. [DOI] [PubMed] [Google Scholar]
- 12.Harris WH, McCarthy JC Jr., O’Neill DA. Femoral component loosening using contemporary techniques of femoral cement fixation. J Bone Joint Surg Am. 1982. Sep;64(7):1063–7. Epub 1982/09/01. [PubMed] [Google Scholar]
- 13.Engh CA, Massin P, Suthers KE. Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop Relat Res. 1990. Aug(257):107–28. Epub 1990/08/01. [PubMed] [Google Scholar]
- 14.Massin P, Schmidt L, Engh CA. Evaluation of cementless acetabular component migration. An experimental study. J Arthroplasty. 1989. Sep;4(3):245–51. Epub 1989/09/01. [DOI] [PubMed] [Google Scholar]
- 15.Gray RJ. Class of K-sample tests for comparing the cumulative incidence of a competing risk. Ann Stat. 1988. (16):1141–54. [Google Scholar]
- 16.Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc. 1958. (53(282)):457–81. [Google Scholar]
- 17.Lachiewicz PF. Porous-coated total hip arthroplasty in rheumatoid arthritis. J Arthroplasty. 1994. Feb;9(1):9–15. Epub 1994/02/01. [DOI] [PubMed] [Google Scholar]
- 18.Mäkelä KT, Eskelinen A, Pulkkinen P, Virolainen P, Paavolainen P, Remes V. Cemented versus cementless total hip replacements in patients fifty-five years of age or older with rheumatoid arthritis. J Bone Joint Surg Am. 2011. Jan 19;93(2):178–86. Epub 2011/01/21. [DOI] [PubMed] [Google Scholar]
- 19.Zwartelé RE, Witjes S, Doets HC, Stijnen T, Pöll RG. Cementless total hip arthroplasty in rheumatoid arthritis: a systematic review of the literature. Arch Orthop Trauma Surg. 2012. Apr;132(4):535–46. Epub 2011/11/25. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Zwartelé R, Pöll RG. Cemented total hip arthroplasty in rheumatoid arthritis. A systematic review of the literature. Hip Int. 2013. Mar-Apr;23(2):111–22. Epub 2013/05/01. [DOI] [PubMed] [Google Scholar]
- 21.Berry DJ, von Knoch M, Schleck CD, Harmsen WS. Effect of femoral head diameter and operative approach on risk of dislocation after primary total hip arthroplasty. J Bone Joint Surg Am. 2005. Nov;87(11):2456–63. Epub 2005/11/03. [DOI] [PubMed] [Google Scholar]
- 22.Ravi B, Escott B, Shah PS, Jenkinson R, Chahal J, Bogoch E, et al. A systematic review and meta-analysis comparing complications following total joint arthroplasty for rheumatoid arthritis versus for osteoarthritis. Arthritis Rheum. 2012. Dec;64(12):3839–49. Epub 2012/11/30. [DOI] [PubMed] [Google Scholar]
- 23.Gausden EB, Parhar HS, Popper JE, Sculco PK, Rush BNM. Risk Factors for Early Dislocation Following Primary Elective Total Hip Arthroplasty. J Arthroplasty. 2018. May;33(5):1567–71.e2. Epub 2018/02/06. [DOI] [PubMed] [Google Scholar]
- 24.Bettencourt JW, Wyles CC, Osmon DR, Hanssen AD, Berry DJ, Abdel MP. Outcomes of primary total hip arthroplasty following septic arthritis of the hip : a case-control study. Bone Joint J. 2022. Feb;104-b(2):227–34. [DOI] [PubMed] [Google Scholar]
- 25.Schrama JC, Fenstad AM, Dale H, Havelin L, Hallan G, Overgaard S, et al. Increased risk of revision for infection in rheumatoid arthritis patients with total hip replacements. Acta Orthop. 2015;86(4):469–76. Epub 2015/03/18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Berbari EF, Hanssen AD, Duffy MC, Steckelberg JM, Ilstrup DM, Harmsen WS, et al. Risk factors for prosthetic joint infection: case-control study. Clin Infect Dis. 1998. Nov;27(5):1247–54. Epub 1998/11/25. [DOI] [PubMed] [Google Scholar]
- 27.Momohara S, Kawakami K, Iwamoto T, Yano K, Sakuma Y, Hiroshima R, et al. Prosthetic joint infection after total hip or knee arthroplasty in rheumatoid arthritis patients treated with nonbiologic and biologic disease-modifying antirheumatic drugs. Mod Rheumatol. 2011. Oct;21(5):469–75. Epub 2011/02/15. [DOI] [PubMed] [Google Scholar]
- 28.Cordtz RL, Zobbe K, Højgaard P, Kristensen LE, Overgaard S, Odgaard A, et al. Predictors of revision, prosthetic joint infection and mortality following total hip or total knee arthroplasty in patients with rheumatoid arthritis: a nationwide cohort study using Danish healthcare registers. Ann Rheum Dis. 2018. Feb;77(2):281–8. Epub 2017/11/04. [DOI] [PubMed] [Google Scholar]
- 29.Bogoch ER, Moran EL. Bone abnormalities in the surgical treatment of patients with rheumatoid arthritis. Clin Orthop Relat Res. 1999. Sep(366):8–21. Epub 2000/01/11. [DOI] [PubMed] [Google Scholar]
- 30.Hayer S, Niederreiter B, Kalkgruber M, Wanic K, Maißner J, Smolen JS, et al. Analysis of combined deficiency of interleukin-1 and −6 versus single deficiencies in TNF-mediated arthritis and systemic bone loss. Bone Joint Res. 2022. Jul;11(7):484–93. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Luo P, Wang P, Xu J, Hou W, Xu P, Xu K, et al. Immunomodulatory role of T helper cells in rheumatoid arthritis : a comprehensive research review. Bone Joint Res. 2022. Jul;11(7):426–38. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Rud-Sørensen C, Pedersen AB, Johnsen SP, Riis AH, Overgaard S. Survival of primary total hip arthroplasty in rheumatoid arthritis patients. Acta Orthop. 2010. Feb;81(1):60–5. Epub 2010/02/26. [DOI] [PMC free article] [PubMed] [Google Scholar]