Cobalt Chromium Alloy Femoral Heads Research Articles

Correction to: Short‑term clinical and radiographic outcomes of total hip arthroplasty with PMPC‑grafted highly cross‑linked polyethylene liners against 32‑mm femoral heads

A correction to this paper has been published: https://doi.org/10.1007/s10047-021-01258-4

Risk Stratification Algorithm for Management of Head-Neck Taper Tribocorrosion in Patients with Metal-on-Polyethylene Total Hip Arthroplasty

Abstract: Adverse local tissue reactions (ALTRs) were initially reported as complications associated with metal-on-metal (MoM) bearings; however, there is increasing concern regarding the occurrence of adverse local tissue reactions from mechanically assisted crevice corrosion (MACC) at the femoral head-neck junction or between other modular junctions of the implant containing cobalt chromium parts in patients with metal-on-polyethylene (MoP) bearings. ALTR due to MACC at the head-neck junction has primarily been reported in association with cobalt chromium alloy femoral heads. As pain following total hip arthroplasty may have various intrinsic and extrinsic causes, a systematic approach to evaluation (risk stratification algorithm) based on the currently available data is recommended to optimize patient management. Evaluation should begin by ruling out common causes of pain, including component loosening and periprosthetic joint infection. While specialized tests such as blood metal analysis and metal artifact reduction sequence magnetic resonance imaging (MARS MRI) are useful modalities in evaluating for ALTRs, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. There should be a low threshold to perform a systematic evaluation for ALTR due to MACC in patients with metal-on-polyethylene total hip arthroplasty as early recognition and diagnosis is critical, as delays in appropriate treatment initiation may result in soft-tissue damage, which complicates surgical treatment and is associated with a higher risk of complications and poorer patient outcomes.

Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head

BackgroundGross trunnion failure (GTF) is a rare complication in total hip arthroplasty (THA) reported across a range of manufacturers. Specific lots of the Stryker low friction ion treatment (LFIT) anatomic cobalt chromium alloy (CoCr) V40 femoral head were recalled in August 2016. In part, the recall was based out of concerns for disassociation of the femoral head from the stem and GTF. MethodsWe report on 28 patients (30 implants) with either GTF (n = 18) or head-neck taper corrosion (n = 12) of the LFIT CoCr femoral head and the Accolade titanium-molybdenum-zirconium-iron alloy femoral stems. All these cases were associated with adverse local tissue reactions requiring revision of the THA. ResultsIn our series, a conservative estimate of the incidence of failure was 4.7% (n = 636 total implanted) at 8.0 ± 1.4 years from the index procedure. Failures were associated with a high-offset 127° femoral stem neck angle and increased neck lengths; 43.3% (13 of 30) of the observed failures included implant sizes outside the voluntary recall (27.8% [5 of 18] of the GTF and 75.0% [8 of 12] of the taper corrosion cases). Serum cobalt and chromium levels were elevated (cobalt: 8.4 ± 7.0 μg/mL; chromium: 3.4 ± 3.3 μ/L; cobalt/chromium ratio: 3.7). The metal artifact reduction sequence magnetic resonance imaging demonstrated large cystic fluid collections typical with adverse local tissue reactions. During revision, a pseudotumor was observed in all cases. Pathology suggested a chronic inflammatory response. Impending GTF could be diagnosed based on aspiration of black synovial fluid and an oblique femoral head as compared with the neck taper on radiographs. ConclusionIn our series of the recalled LFIT CoCr femoral head, the risk of impending GTF or head-neck taper corrosion should be considered as a potential diagnosis in a painful LFIT femoral head and Accolade titanium-molybdenum-zirconium-iron alloy THA with unknown etiology. Almost half of the failures we observed included sizes outside of the voluntary recall.

Ten-Year Cross-Sectional Study of Mechanically Assisted Crevice Corrosion in 1352 Consecutive Patients With Metal-on-Polyethylene Total Hip Arthroplasty

BackgroundMechanically assisted crevice corrosion (MACC) in metal-on-polyethylene total hip arthroplasty (THA) is of concern, but its prevalence, etiology, and natural history are incompletely understood. MethodsFrom January 2003 to December 2012, 1352 consecutive THA surgeries using a titanium stem, cobalt-chromium alloy femoral head, and highly cross-linked polyethylene liner from a single manufacturer were performed. Patients were followed at 1-year and 5-year intervals for surveillance, but also seen earlier if they had symptoms. Any patient with osteolysis >1 cm (n = 3) or unexplained pain (n = 85) underwent examination, radiographs, complete blood count, erythrocyte sedimentation rate, and C-reactive protein, as well as tests for serum cobalt and chromium levels. ResultsSymptomatic MACC was present in 43 of 1352 patients (3.2%). Prevalence of MACC by year of implant ranged from 0% (0 of 61, 2003; 0 of 138, 2005) to 10.5% (17 of 162; 2009). The M/L Taper stem had a greater prevalence (4.9%) of MACC than all other Zimmer (Zimmer, Inc, Warsaw, IN) 12/14 trunnion stem types combined (1.2%; P < .001). Twenty-seven of 43 (62.8%) patients have undergone revision surgery, and 16 of 43 (37.2%) patients have opted for ongoing surveillance. Comparing symptomatic THA patients with and without MACC, no demographic, clinical, or radiographic differences were found. MACC was significantly more common in 0 length femoral heads (compared with both −3.5 mm and +3.5 mm heads). ConclusionThe prevalence of MACC in metal-on-polyethylene hips is higher in this cross-sectional study than previously reported. A significantly higher prevalence was found in patients with M/L Taper style stem and THA performed both in 2009 and also between 2009 and 2012 with this manufacturer.

Biotribological study of multilayer coated metal-on-metal hip prostheses in a hip joint simulator

Metal-on-metal (MOM) hip joint bearings have demonstrated low wear rates and nowadays this contact pair has being considered as an alternative to metal-on-polymer (MOP) joint replacements. However, wear of MOM joints is a concern due to the toxicity and biological reaction of wear debris and metallic corrosion. This has motivated to investigate the possibility to apply thin hard coatings on metallic heads to reduce the wear and metallic ion release. The aim of the present study was to investigate the wear properties of metal-on-metal hip prostheses with surface engineered femoral heads using a multilayer coating (TiN/CrN)×3, in comparison with metal-on-metal pairs in a hip joint simulator. Different surface PVD coatings were applied on surgical grade wrought cobalt–chromium alloy femoral heads: multilayer (TiN/CrN)×3, CrN single layer and diamond-like carbon (DLC). These femoral heads were tested against high carbon content cast cobalt–chromium alloy acetabular cups using a three-axial multi-station hip joint simulator (FIME II). During the wear tests three directions of motion were applied with the following amplitudes: flexion–extension (FE) ±23°, abduction–adduction (AA) ±23° and internal–external (IER) ±8°. All components were tested at 1.2Hz under a Paul-type loading curve and bovine calf serum solution as lubricant. Results showed that both; the PVD coatings protects the femoral heads reducing wear up to 5 times in the case of the DLC coating and 28 and 55 times in the case of (TiN/CrN)×3 and CrN respectively compared with the MOM femoral heads.

Long‐term evaluation of a compliant cushion form acetabular bearing for hip joint replacement: A 20 million cycles wear simulation

Soft bearing materials that aim to reproduce the tribological function of the natural joint are gaining popularity as an alternative concept to conventional hard bearing materials in the hip and knee. However, it has not been proven so far that an elastic cushion bearing can be sufficiently durable as a long term (∼20 years) articulating joint prosthesis. The use of new bearing materials should be supported by accurate descriptions of the implant following usage and of the number, volume, and type of wear particles generated. We report on a long-term 20 million cycle (Mc) wear study of a commercial hip replacement system composed of a compliant polycarbonate-urethane (PCU) acetabular liner coupled to a cobalt-chromium alloy femoral head. The PCU liner showed excellent wear characteristics in terms of its low and steady volumetric wear rate (5.8-7.7 mm(3)/Mc) and low particle generation rate (2-3 × 10(6) particles/Mc). The latter is 5-6 orders of magnitude lower than that of highly cross-linked polyethylene and 6-8 orders of magnitude lower than that of metal-on-metal bearings. Microscopic analysis of the implants after the simulation demonstrated a low damage level to the implants' articulating surfaces. Thus, the compliant PCU bearing may provide a substantial advantage over traditional bearing materials.

Letter to the Editor: Clinical Comparison of Polyethylene Wear with Zirconia or Cobalt-Chromium Femoral Heads

To the Editor: We read with interest the October 2009 article by Stilling et al. [9] entitled “Clinical Comparison of Polyethylene Wear with Zirconia or Cobalt-Chromium Femoral Heads.” The authors compared linear wear rates from zirconia or cobalt-chromium alloy femoral heads with gamma-irradiated but not remelted polyethylene (PE) liners, finding no difference after a minimum of 5 years in vivo. In their discussion, Stilling et al. noted a limitation of their study was the tetragonal-to-monoclinic phase transformation associated with yttria-stabilized zirconia [1], suggesting the increased “Zr surface roughening and grain pullout provides the potential for accelerated PE wear” and thus explains the similar wear performance between yttria-stabilized zirconia and cobalt-chromium alloy femoral heads. We have observed similar phase transformation and roughening of yttria-stabilized zirconia in retrieval series [8] and in artificial aging studies [7]. However, not all zirconia degrades in vivo. Magnesia-stabilized zirconia [2] also is available for clinical use. Although the tetragonal and monoclinic phases also are present in medical-grade magnesia-stabilized zirconia, its microstructure mainly consists of tetragonal precipitates in a cubic matrix, which tends to inhibit tetragonal-to-monoclinic phase transformation [5]. Magnesia-stabilized zirconia has proven to be stable and free from degradation and roughening in retrieval series [8] and in artificial aging studies [7]. In addition, hip wear simulator data in our laboratory comparing 28-mm femoral heads of different materials with 10-Mrad cross-linked/remelted PE revealed wrought cobalt-chromium alloy [3, 4] femoral heads produce higher gravimetric wear at 3 M cycles [6]. We continued this simulator study to 7 M cycles and found the difference in gravimetric wear between cobalt-chromium alloy and magnesia-stabilized zirconia to increase and have submitted a manuscript based on these data to a journal for review. Finally, Stilling et al. [9] use unnecessarily broad language in their final two paragraphs, repeatedly using the abbreviation Zr to refer to all zirconia, not the unstable yttria-stabilized form examined in their study. For example, the statement that “Zr femoral heads were withdrawn from the commercial market in 2001 owing to incidents of head fracture” is not entirely accurate, because only certain batches of yttria-stabilized zirconia manufactured by Saint Gobain Desmarquest (Evreux, France) were recalled. Magnesia-stabilized zirconia was not affected by the recall, and no cases of magnesia-stabilized zirconia fracture have been reported. Although yttria-stabilized zirconia is susceptible to low-temperature degradation and has all but completely disappeared from the market, magnesia-stabilized zirconia has proven to be stable and safe in clinical use. Our hip simulator data suggest the use of magnesia-stabilized zirconia femoral heads will lead to a reduction in wear in vivo compared with cobalt-chromium alloy heads, even with cross-linked acetabular liners.

Prediction of elastic deformation of acetabular cups and femoral heads for lubrication analysis of artificial hip joints

Fluid film lubrication analysis for artificial hip joints often requires the determination of the elastic deformation of the bearing surfaces of both the acetabular cup and the femoral head. This is generally not a trivial task, because of the complex spherical geometries and non-uniform structural supports due to the bone and cement involved. It is particularly important that an efficient numerical method is employed, with a reasonably small amount of computing time required. The normal elastic deformation of spherical bodies, with particular reference to the acetabular cup and the femoral head for artificial hip joints, was determined in the present study using the two-dimensional spherical fast Fourier transform (SFFT) technique. A cobalt-chromium alloy femoral head was considered, in combination with either an ultra-high molecular weight polyethylene acetabular cup fixed to a metallic (rigid) backing or a cobalt-chromium alloy cup fixed to an equivalent layer representing bone and cement. A representative pressure distribution was applied around both the central region of the cup and the anatomical position with a 45° inclination angle. The elastic deformation determined from the SFFT method was compared with that directly calculated from the finite element method, and excellent agreement was found when the pressure distribution was applied around the central region. Even when the pressure distribution was applied anatomically and extended to the edge of the cup, reasonably good overall agreement of the predicted elastic deformation was achieved. Furthermore, both the computing time and the storage space required for the SFFT method were significantly reduced, compared with the conventional direct summation method used by Jagatia and Jin.