Why do some titanium-alloy total hip arthroplasty modular necks fail? (original) (raw)
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Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches
Materials
Titanium (Ti) alloys have been proven to be one of the most suitable materials for orthopaedic implants. Dual modular stems have been introduced to primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. This systematic review highlights information acquired for dual modular Ti stem complications published in the last 12 years and offers a conclusive discussion of the gathered knowledge. Articles referring to dual modular stem usage, survivorship, and complications in English were searched from 2009 to the present day. A qualitative synthesis of literature was carried out, excluding articles referring solely to other types of junctions or problems with cobalt-chromium alloys in detail. In total, 515 records were identified through database searching and 78 journal articles or conference proceedings were found. The reasons for a modular neck fracture of a Ti alloy are multifactorial. Even though dual modular stems have not s...
International Orthopaedics, 2020
Introduction Revision of a well-fixed stem due to unexpected modular neck fracture is a catastrophe for the patient and a challenge for the surgeon. This study aimed to test the possibility of predicting interchangeable neck fracture from serum levels of the stem/neck alloy-consisting metals. Materials and methods Nineteen patients at high risk for interchangeable neck fracture were randomly selected out of a cohort of 680 bimodular stems made from Ti6Al4V alloy. Serum levels of titanium, aluminium and vanadium were determined. Nine ageand gender-matched patients were used as controls. Results Mean serum levels of Ti were 6.04 ± 2.52 μg/L, of Al 3.89 ± 1.68 μg/L and of V 0.07 ± 0.04 μg/L in the high-risk group, and 8.22 ± 4.74 μg/L, 4.99 ± 3.98 μg/L and 0.27 ± 0.44 μg/L in the low-risk group, respectively. No statistically significant differences were found between the groups. Discussion Interchangeable neck fracture of bimodular femoral stems cannot be predicted from serum trace element analysis.
The Journal of Arthroplasty, 2014
Modular neck femoral stems have a higher-than-anticipated rate of failure in registry results, but large single-center cohort studies are lacking. This is a retrospective cohort of 152 hips implanted with a single titanium stem with a modular titanium neck, presenting clinical, radiographic, and metal ion results at a mean 4.5 year follow-up. Five hips were revised during the study period, for an overall Kaplan-Meier survival of 0.894 at 8 years. There was one modular neck fracture (0.66%), but others demonstrated corrosion or adverse tissue reaction.
Modeling Simulation and Optimization - Focus on Applications, 2010
The replacement of the natural hip with artificial components is a well established procedure in orthopaedic medicine to alleviate pain from the diseased joint. The total hip replacement (THR) consists of a femoral component or stem and an acetabular cup. These are made as either one piece or modular designs. Modular femoral components have become popular among surgeons because neck length and offset can be adjusted intraoperatively, providing increased versatility without any need for a large inventory. In addition, modular heads allow for mixed alloy systems such as the combination of a titanium alloy stem with a cobalt-chromium or ceramic head. Apart from the neck/head connection, there are femoral stem designs with extra areas of modularity.
The innovation trap: modular neck in total hip arthroplasty
DOAJ (DOAJ: Directory of Open Access Journals), 2017
Background: Innovations play a key role in the success of orthopeadic surgery. However, even minor modifications in the established concepts and designs may result in disasters. We face an endemic of modular femoral neck failures occurring in fully modular total hip arthroplasty (24 of approx.4000 implanted), which has been popular in Slovenia for the last 20 years. Its most unfortunate consequences challenge us to seriously address this problem. The aim of this report was to analyse the volume, and the causes of the problem, on the one hand, and to propose possible solutions, on the other. Methods: The literature was searched for problems associated with Profemur Z fully-modular femoral stem, made of titanium alloy (Ti6Al4V)or earlier versions with the same taper-cone design.The available hip arthroplasty registries were used to determine failure rates associated with the above mentioned design. The mechanisms of failure were studied in order to get in-depth understanding of this hip reconstruction device. Results: Since 2010, several case reports on catastrophic modular femoral neck fractures of Profemur Z have been published. In Slovenia the first case was described in 2012. The first two large series with modular femoral neck fractures were reported in 2016. The Australian Joint Replacement Registry was the first to discover elevated revision rates due to fractures of this hip reconstruction system. In 2010, the Agency for Medicinal Products and Medical Devices of the Republic of Slovenia (JAZMP) received the first 2 reports on Profemur Z modular neck complications, submitted by foreign institutions. The first Slovenian report dates back to 2012, and altogether 7 reports from Slovene hospitals had been received by December 2016. Corrosion at the neck-taper interface, where two equal or different materials are subject to constant wear in the presence of body fluids, was assumed to be responsible for the unacceptably high failure rates. Conclusions: Manufacturers are responsible for producing and marketing safe devices. However, orthopaedic surgeons should carefully monitor all innovations for any adverse effects. JAZMP took appropriate measures only after receiving urgent field safety corrective notice from the manufacturer in 2015, stating that all lots of long modular necks made from cobalt-chromium alloy should be withdrawn. It should be noted here that the regulatory agency of the Republic of Slovenia was not receiving vigilance reports as appropriate, and was thus unaware of the dimension of this problem. A national arthroplasty registry would have most probably alerted the orthopaedic community to this questionable innovation earlier. Regulatory bodies should set up such a registry for the benefit of our patients as soon as possible.
Modular Neck Total HIP Arthroplasty – A Perfect Storm
Hip International, 2016
Fracture rates were found to be 1.4% by Grupp et al (6) in a retrospective series of 5000 uncemented THA. Disassociations have been reported in some case reports but appear to be a rare event. The present study identified neck notching in a cohort of our patient population undergoing THA and possible factors that may have contributed to notching in a cohort of patients receiving a Kinectiv modular neck Technology (Zimmer, Warsaw, Indiana). Methods A retrospective study was conducted at our regional institution. We reviewed the results of 301 consecutive THA performed between 2008 and 2013 by the senior author (EK), using the Kinectiv modular neck Technology (Zimmer, Warsaw, Indiana). The analysis involved a review of the patient's records, operative notes, and plain radiographs. In selected cases, we obtained serum metal ions levels. The data obtained were cross-referenced with a list of used prostheses provided from the company. The primary outcome of this study was the presence of neck notching requiring revision. We undertook this review based on the intraoperative findings of 2 early THA failures. In both cases, significant notching of the modular neck component was noted to be present and considered to be a potential cause of failure. We defined neck notching requiring revision as any evidence of a divot in the superior part of the titanium neck seen on plain radiographs (Figs. 1-3). This was later confirmed intra operatively during revision.
Fatigue Fracture in Dual Modular Revision Total Hip Arthroplasty Stems
The Journal of Arthroplasty, 2014
We report on two patients with fracture of a modular, tapered and distally fixed, uncemented titanium revision hip stem, not previously described. A failure analysis revealed that the cause of the fractures was the development of fatigue cracks in the mid-stem cobalt-chromium modular junction ending in corrosionfatigue failure. No material defects or stress risers were found in any of the implants. The diameter of the midstem modular junction might be undersized for use in heavy and active patients. We also report a new way of detecting an undisplaced fracture at the modular junction, using the scout image from a computed tomography (CT) scan; a technique that can be used when plain radiographs are inconclusive.