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Daher J, Desai B, Nammour M, Warren M, Chimento G. Long-term Follow-up on Revisions of a Recalled Large Head Metal-on-metal Hip Prosthesis: A Single Surgeon Series. Arthroplast Today 2023; 22:101163. [PMID: 37521732 PMCID: PMC10374868 DOI: 10.1016/j.artd.2023.101163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/29/2023] [Accepted: 05/14/2023] [Indexed: 08/01/2023] Open
Abstract
Background In 2010, a recall was issued for a specific monoblock large head metal-on-metal (MoM) hip prosthesis due to short-term revision rates of 12%-13% (articular surface replacement, DePuy Orthopaedics, Inc., Warsaw, IN). High complication, infection, and rerevision rates for revised MoM implants have been reported. The purpose of the study is to report long-term outcomes and trend metal ion levels of this recalled MoM prosthesis from a single surgeon series. Methods Retrospective chart review was performed on all patients that underwent revision of large MoM hip replacements between 2010 and 2015. Pre- and post-revision Harris Hip Score (HHS), cup abduction angles, anteversion angles, and cup sizes were compared. Survivorship and HHS were the primary outcomes measured; serum cobalt and chromium levels were secondary outcomes. Multivariate linear regression was used to examine the correlation between prerevision serum metal ion levels and HHS. Results A total of 24 hips (21 patients) met inclusion criteria. Mean time to revision was 4.12 years ± 1.1. Mean follow-up was 10.0 years (7-11.9 years). Mean HHS increased significantly after revision from 48.5 to 89.5 (P < .001). Higher prerevision cobalt levels were correlated with lower prerevision HHS (cobalt R = 0.25; chromium R = 0.3160). There was no correlation with prerevision cobalt (P = .2671) or chromium (P = .3160) with postrevision HHS. Most recent metal ion testing revealed a significant decrease in both cobalt (P = .0084) and chromium (P = .0115). Survival rate is 100%. Conclusions Our study showed excellent survivorship and outcomes at 10 years. There were no failures for any reason including infection. This differs from previous studies and confirms excellent long-term results are possible with revision of this recalled MoM implant.
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Affiliation(s)
- Jimmy Daher
- Department of Orthopaedic Surgery, Ochsner Medical Center, New Orleans, LA, USA
| | - Bhumit Desai
- Department of Orthopaedic Surgery, Ochsner Medical Center, New Orleans, LA, USA
- Ochsner Clinical School, University of Queensland School of Medicine, New Orleans, LA, USA
| | - Michael Nammour
- Department of Orthopaedic Surgery, Ochsner Medical Center, New Orleans, LA, USA
| | - Michael Warren
- Department of Orthopaedic Surgery, Ochsner Medical Center, New Orleans, LA, USA
| | - George Chimento
- Department of Orthopaedic Surgery, Ochsner Medical Center, New Orleans, LA, USA
- Ochsner Clinical School, University of Queensland School of Medicine, New Orleans, LA, USA
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Do cobalt and chromium blood metal ion levels normalize after revision of failed metal-on-metal total hip replacements? Arch Orthop Trauma Surg 2023; 143:1217-1221. [PMID: 34724103 DOI: 10.1007/s00402-021-04206-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Increased cobalt (Co) and chromium (Cr) serum levels are one reason for revision surgery in metal on metal (MoM) total hip arthroplasty (THA) patients. Dual mobility liners are a simple revision option; however, they preserve the metal shell and stem and it is therefore not clear if metal ion levels will fully normalize after revision surgery. MATERIAL AND METHODS Between April 2013 and December 2017 25 hips (24 patients) underwent revision from a MoM THA to an off-label dual mobility liner. Five patients were lost to follow-up and one patient refused leaving 18 patients (11 men, 7 female, average age 63.9 years) for pre- and postoperative metal ion level blood tests at a minimum follow-up of 2 years. RESULTS Fourteen patients were revised for osteolysis, two for elevated metal ion levels and two for fluid or cysts around the femoral or acetabular component. The average preoperative Co and Cr levels were 8.3 µg/l and 5.0 µg/l, respectively. At a minimum follow-up of 2 years (30-95 months), metal ions dropped to 0.8 µg/l. Harris Hip Score (HHS), Hip Osteoarthritis Outcome Score (HOOS), Visual Analog Scale (VAS) and the UCLA activity score improved non-significantly from pre- to postoperative. There was one postoperative complication in the study cohort. One patient with persisting pain required revision surgery to a standard acetabular component during the follow-up period. CONCLUSION The off-label use of a dual-mobility liner in the current study resulted in normalization of the metal ion levels suggesting that preserving the cobalt-chromium acetabular component has little impact on ion levels. In addition, dual mobility liners have a low complication and revision rate.
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Pai FY, Ma HH, Chou TFA, Huang TW, Huang KC, Tsai SW, Chen CF, Chen WM. Risk factors and modes of failure in the modern dual mobility implant. A systematic review and meta-analysis. BMC Musculoskelet Disord 2021; 22:541. [PMID: 34126990 PMCID: PMC8204435 DOI: 10.1186/s12891-021-04404-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 05/24/2021] [Indexed: 02/08/2023] Open
Abstract
Background The aims of this meta-analysis were to: (1) validate the outcome of modern dual mobility (DM) designs in patients who had undergone primary and revision total hip arthroplasty (THA) procedures and (2) to identify factors that affect the outcome. Methods We searched for studies that assessed the outcome of modern DM-THA in primary and revision procedures that were conducted between January, 2000 to August, 2020 on PubMed, MEDLINE, Cochrane Reviews and Embase. The pooled incidence of the most common failure modes and patient reported outcomes were evaluated in patients who have received: (1) primary THA, (2) revision THA for all causes or (3) for recurrent dislocation. A meta-regression analysis was performed for each parameter to determine the association with the outcome. The study design of each study was assessed for potential bias and flaws by using the quality assessment tool for case series studies. Results A total of 119 studies (N= 30016 DM-THAs) were included for analysis. The mean follow-up duration was 47.3 months. The overall implant failure rate was 4.2% (primary: 2.3%, revision for all causes: 5.5%, recurrent dislocation: 6.0%). The most common failure modes were aseptic loosening (primary: 0.9%, revision for all causes: 2.2%, recurrent dislocation: 2.4%), septic loosening (primary:0.8%, revision for all causes: 2.3%, recurrent dislocation: 2.5%), extra-articular dislocation (primary:0.6%, revision for all causes:1.3%, recurrent dislocation:2.5%), intra-prosthetic dislocation (primary:0.8%, revision for all causes:1.0%, recurrent dislocation:1.6%) and periprosthetic fracture (primary:0.9%, revision for all causes:0.9%, recurrent dislocation:1.3%). The multi-regression analysis identified younger age (β=-0.04, 95% CI -0.07 – -0.02) and female patients (β=3.34, 95% CI 0.91–5.78) were correlated with higher implant failure rate. Age, gender, posterolateral approach and body mass index (BMI) were not risk factors for extra-articular or intra-prosthetic dislocation in this cohort. The overall Harris hip score and Merle d’Aubigné score were 84.87 and 16.36, respectively. Level of evidence of this meta-analysis was IV. Conclusion Modern dual-mobility designs provide satisfactory mid-term implant survival and clinical performance. Younger age and female patients might impact the outcome after DM-THA. Future research directions should focus on, (1) long-term outcome of modern dual-mobility design, including specific concerns such as intra-prosthetic dislocation and elevated metal ion, and (2) cost-effectiveness analysis of dual-mobility implant as an alternative to conventional THA for patients who are at high risk of dislocation. Supplementary Information The online version contains supplementary material available at 10.1186/s12891-021-04404-4.
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Affiliation(s)
- Fu-Yuan Pai
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan.,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | - Hsuan-Hsiao Ma
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan.,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | - Te-Feng Arthur Chou
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan.,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | - Tsan-Wen Huang
- Chang Gung University College of Medicine, Taoyuan, Taiwan.,Department of Orthopaedic Surgery, Chang-Gung Memorial Hospital, Chiayi, Taiwan
| | - Kuo-Chin Huang
- Chang Gung University College of Medicine, Taoyuan, Taiwan.,Department of Orthopaedic Surgery, Chang-Gung Memorial Hospital, Chiayi, Taiwan
| | - Shang-Wen Tsai
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan.,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | - Cheng-Fong Chen
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan. .,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan.
| | - Wei-Ming Chen
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shi-Pai Road, Taipei 112, Taiwan.,Department of Orthopaedics, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
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Thompson Z, Khoshbin A, Ward S, Waddell JP, Atrey A. The early- to medium-term results of a hemispherical, porous coated acetabular shell with multiple different bearing combinations are excellent with the exception of metal-on-metal. INTERNATIONAL ORTHOPAEDICS 2020; 44:2537-2543. [PMID: 33068147 DOI: 10.1007/s00264-020-04817-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/15/2020] [Indexed: 11/25/2022]
Abstract
PURPOSE This study prospectively reports survivorship and radiographic and clinical outcomes following primary elective total hip arthroplasty (THA) using a novel single hemispherical, porous-coated acetabular cup with five different bearing combinations and a minimum of five year follow-up. METHODS Continuing post-market release monitoring of this cup, we prospectively enrolled 108 patients (121 THA) between 2009 and 2015. We followed this cohort by examining survivorship, in addition to clinical and radiological outcomes for metal-on-metal (MoM) compared with non-MoM bearing combinations (ceramic-on-ceramic, oxinium-on-polyethylene, ceramic-on-metal, and metal-on-polyethylene). RESULTS All 108 (121 hips) patients were followed up. Average age at time of surgery was 45.1 years (range 19 to 71 years) of which 42.1% were males. A total of seven (5.8%) cups were revised, all of which were MoM. No osteolysis was observed in any of the patients at the latest visit with a mean follow-up of 9.1 ± 1.7 years (range 4.4-10.7 years). With MoM excluded, survivorship of the cup at five years is 97.8%. Survivorship for MoM implants was 90.0%. Validated hip scores showed significant improvements for all bearing types and no significant difference between groups at latest follow-up (p = 0.614). There was no cup migration with any bearing surface. CONCLUSION This cup showed excellent survivorship at five year follow-up, except for patients receiving a MoM articulation. While there were concerns over the early survivorship of this cup, our cohort and joint registry data confirm excellent outcomes.
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Affiliation(s)
- Zoe Thompson
- University of Toronto, 27 King's College Cir, Toronto, ON, M5S, Canada
| | - Amir Khoshbin
- St. Michael's Hospital, University of Toronto, 30 Bond St., Toronto, ON, M5B 1W8, Canada
| | - Sarah Ward
- St. Michael's Hospital, University of Toronto, 30 Bond St., Toronto, ON, M5B 1W8, Canada
| | - James P Waddell
- St. Michael's Hospital, University of Toronto, 30 Bond St., Toronto, ON, M5B 1W8, Canada
| | - Amit Atrey
- St. Michael's Hospital, University of Toronto, 30 Bond St., Toronto, ON, M5B 1W8, Canada.
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Rueckl K, Liebich A, Bechler U, Springer B, Rudert M, Boettner F. Return to sports after hip resurfacing versus total hip arthroplasty: a mid-term case control study. Arch Orthop Trauma Surg 2020; 140:957-962. [PMID: 32296965 DOI: 10.1007/s00402-020-03414-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Indexed: 01/23/2023]
Abstract
BACKGROUND Hip resurfacing (HR) is an alternative to conventional total hip arthroplasty (THA) for the treatment of osteoarthritis (OA) in very active, young male patients. However, there is no study in the literature that has proven its benefits for high-impact sport over standard primary THA. The aim of the current study was to investigate the return to sport and function level of male patients after THA vs. HR. MATERIALS AND METHODS This prospective study is based on a telephone questionnaire for general health and sports activities. 40 HRs were matched with 40 THAs based on preoperative University of California Arthroplasty Score (UCLA), BMI, age at time of surgery and age at follow-up. The mean follow-up period was 56 months (range 24-87 months). RESULTS HR patients showed a significantly higher High-activity arthroplasty score (HAAS) (14.9 vs. 12.9, p < 0.001) and Lower extremity activity scale (LEAS) (15.9 vs. 14.1, p < 0.001) and reached significantly higher values in the Hip cycle score (HCS) (44.7 vs. 35.7 p = 0.037) and Impact score (IS) (40.9 vs. 29.6, p < 0.002) than THA patients. No significant differences were found in the HOOS function section (91.4 vs. 90.3, p = 0.803) and the Pain numeric rating scale (NRS)-11 (0.6 vs. 0.9 p = 0.169). Patients with HR had a slightly higher Harris hip score (HHS) (97.8 vs. 95.6, p = 0.015) CONCLUSION: The current study suggests that young male patients are able to engage in higher activity levels after HR compared to standard THA.
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Affiliation(s)
- Kilian Rueckl
- Adult Reconstruction and Joint Replacement Division, Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.,Department of Orthopedic Surgery, Koenig-Ludwig-Haus, University of Wuerzburg, Brettreichstrasse 11, 97074, Wuerzburg, Germany
| | - Alina Liebich
- Adult Reconstruction and Joint Replacement Division, Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.,Department of Orthopedic Surgery, Koenig-Ludwig-Haus, University of Wuerzburg, Brettreichstrasse 11, 97074, Wuerzburg, Germany
| | - Ulrich Bechler
- Adult Reconstruction and Joint Replacement Division, Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA
| | - Bernhard Springer
- Adult Reconstruction and Joint Replacement Division, Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA
| | - Maximilian Rudert
- Department of Orthopedic Surgery, Koenig-Ludwig-Haus, University of Wuerzburg, Brettreichstrasse 11, 97074, Wuerzburg, Germany
| | - Friedrich Boettner
- Adult Reconstruction and Joint Replacement Division, Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.
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Affatato S, Castiello E, Amendola L, Comitini S, Prudhon JL, Tigani D. Revision of a Monoblock Metal-on-Metal Cup Using a Dual Mobility Component: Is It a Reasonable Option? MATERIALS (BASEL, SWITZERLAND) 2020; 13:ma13092040. [PMID: 32349434 PMCID: PMC7254332 DOI: 10.3390/ma13092040] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/22/2020] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
Revision of large-diameter, monoblock acetabular components for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA) is correlated to a high amount of complications. For this reason, performing a limited revision by conversion to a dual mobility (DM) without acetabular component exchange has been proposed in order to limit these complications. Although DM bearing offers an easy solution avoiding the intraoperative and time-associated complications, concern about polyethylene wear and stability remains due to the difference regarding the design, the coverage angle and the clearance of the two implants. In order to evaluate the performance of this new solution with the new material to prevent the possibility of failure it is essential to conduct a review of the literature A qualitative systematic review of the literature has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, EMBASE, Google Scholar, and Scopus for English and French articles between January 2000 and October 2019 was performed, with the primary objective of finding articles about dual mobility bearing coupling with large metal-on-metal cup in the case of hip revision procedure. Various combinations of the key words were used in the search strategy. Thirteen articles with DM bearing mated with MoM cup were analyzed. Of the 130 hip revisions selected, with a follow-up from 6 to 53 months, there were a total of 14 with complications (10.77%): four true dislocations (3.08%); six intra-prosthetic dislocations (IPD, 4.6%), two of which presented plastic deformation and polyethylene wear; four other complications (3.08%), included a cup osteolysis, a clicking noise, a superficial infection and a periprosthetic fracture. All the mentioned true dislocations occurred during the first month while IPDs appeared during the first two years from the index revision. In conclusion, according to the literature analyzed, we can stress that the concerns and doubts about mating a DM bearing with large MoM cup cannot be dissolved. It has been pointed out that a DM bearing is not designed for a MoM cup; it is not mechanically tested on MoM cups, which presents different clearance and coverage angles. Predictable complications may occur, such as IPD, polyethylene wear and true dislocation. These complications have been reported at an even higher rate than they were in the eighties, when the first generation of DM implants were of a lower quality of polyethylene and the characteristic of the design was less optimal than modern ones.
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Affiliation(s)
- Saverio Affatato
- Laboratorio di Tecnologia Medica, IRCCS – Istituto Ortopedico Rizzoli, 40100 Bologna, Italy
| | - Emanuela Castiello
- Unità Operativa Complessa di Ortopedia e Traumatologia, Ospedale Maggiore, 40100 Bologna, Italy; (E.C.); (L.A.); (S.C.); (D.T.)
| | - Luca Amendola
- Unità Operativa Complessa di Ortopedia e Traumatologia, Ospedale Maggiore, 40100 Bologna, Italy; (E.C.); (L.A.); (S.C.); (D.T.)
| | - Saverio Comitini
- Unità Operativa Complessa di Ortopedia e Traumatologia, Ospedale Maggiore, 40100 Bologna, Italy; (E.C.); (L.A.); (S.C.); (D.T.)
| | | | - Domenico Tigani
- Unità Operativa Complessa di Ortopedia e Traumatologia, Ospedale Maggiore, 40100 Bologna, Italy; (E.C.); (L.A.); (S.C.); (D.T.)
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Colacchio ND, Wooten CJ, Martin JR, Masonis JL, Fehring TK. Dual Mobility for Monoblock Metal-on-Metal Revision-Is It Safe? J Arthroplasty 2020; 35:508-512. [PMID: 31662280 DOI: 10.1016/j.arth.2019.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/12/2019] [Accepted: 09/17/2019] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Revision of monoblock metal-on-metal (MoM) total hip arthroplasty (THA) is associated with high complication rates. Limited revision by conversion to a dual mobility (DM) without acetabular component extraction may mitigate these complications. However, the concern for polyethylene wear and osteolysis remains unsettled. This study investigates the results of DM conversion of monoblock MoM THA compared to formal acetabular revision. METHODS One hundred forty-three revisions of monoblock MoM THA were reviewed. Twenty-nine were revisions to a DM construct, and 114 were complete revisions of the acetabular component. Mean patient age was 61, 54% were women. Components used, acetabular cup position, radiographic outcomes, serum metal ion levels, and HOOS Jr clinical outcome scores were investigated. RESULTS At 3.9 years of follow-up (range 2-5), there were 2 revisions (6.9%) in the DM cohort, 1 for instability and another for periprosthetic fracture. Among the formal acetabular revision group there was a 20% major complication rate (23/114) and 16% underwent revision surgery (18/114) for aseptic loosening of the acetabular component (6%), deep infection (6%), dislocation (4%), acetabular fracture (3%), or delayed wound healing (6%). In the DM cohort, there were no radiographic signs of aseptic loosening, component migration, or polyethylene wear. One DM patient had a small posterior metadiaphyseal femur lesion that will require close monitoring. There were no other radiographic signs of osteolysis. There were no clinically significant elevations of serum metal ion levels. HOOS Jr scores were favorable. CONCLUSION Limited revision with conversion to DM is a viable treatment option for failed monoblock MoM THA with lower complication rates than formal revision. Limited revision to DM appears to be a safe option for revision of monoblock MoM THA with a cup in good position and an internal geometry free of sharp edges or articular surface damage. Longer follow-up is needed to demonstrate any potential wear implications of these articulations.
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Affiliation(s)
| | - Clint J Wooten
- Department of Orthopaedic Surgery, OrthoCarolina, Charlotte, NC
| | - John R Martin
- Department of Orthopaedic Surgery, OrthoCarolina, Charlotte, NC
| | - John L Masonis
- Department of Orthopaedic Surgery, OrthoCarolina, Charlotte, NC
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Predictive factors for metal ion levels in metal-on-metal total hip arthroplasty. Arch Orthop Trauma Surg 2018; 138:281-286. [PMID: 29260384 DOI: 10.1007/s00402-017-2856-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Indexed: 02/09/2023]
Abstract
INTRODUCTION Although metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacings (HR) have similar bearing surfaces and comparable wear rates, metal ion levels and risk of failure are higher for MoM-THA. The mechanism behind the increased metal ion levels in large head MoM-THA is not completely understood. The current study aims to identify predictive factors for increased metal ion levels in unilateral and bilateral large head MoM-THA. MATERIALS AND METHODS 99 Birmingham modular MoM-THA in 87 patients with metal ion levels at least 36 months after index procedure were analyzed. Mean follow-up time was 61.3 months (range 37-108) and the relationship of the following variables (gender, age, BMI, follow-up time, UCLA Activity Score, cup inclination, femoral head size, bilateral surgery) on metal ion levels were analyzed with multivariate regression models. RESULTS Multivariate regression analysis revealed that bilateral MoM-THA surgery (p < 0.001) had a positive predictive effect on cobalt serum levels, while BMI had a negative (p = 0.018). Female gender (p = 0.012), activity (p = 0.001) and bilateral MoM-THA (p = 0.004) were positively correlated with chromium levels. Positive independent predictors for the cobalt-chromium ratio in the multivariate analysis were overall follow-up time (p = 0.004), bilateral MoM-THA (p < 0.001) and femoral head size (p = 0.007). CONCLUSIONS The data of the current study suggest that bilateral MoM-THA, increased patient activity levels and female gender are associated with increased chromium levels. Patients with larger component size, longer follow-up time and bilateral MoM-THAs have an increased cobalt-chromium ratio. These patients might be at increased risk for adverse local soft tissue reactions secondary to corrosion. Continuous close monitoring is recommended and bearing-surface change should be discussed if local tissue reactions occur.
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