Mid-term results of titanium-titanium modular neck femoral stem in primary total hip arthroplasty.

BACKGROUND: Modular neck femoral stems are advantageous because they can accurately restore the ideal hip geometry using various options in terms of offset, length, and version. However, there are concerns regarding junctional problems. Despite several reports on such issues, there is a lack of study on mid- to long-term results of these stems. The current study evaluated the mid-term results of patients who underwent primary total hip arthroplasty using a titanium-titanium (Ti-Ti) modular neck femoral stem. METHODS: In total, data on 47 hips (42 patients) that could be followed-up for ≥ 5 years after primary total hip arthroplasty using the Ti-Ti modular neck femoral stem from 2011 to 2015 were reviewed. There were 22 male and 20 female patients, and their mean age was 56.3 (range: 31-76) years. The mean follow-up period was 8 (range: 5-12) years. Functional and radiological outcomes, complications, and reoperations were investigated. In addition, we conducted a comparative analysis of the outcomes between those who underwent surgery using the Ti-Ti modular neck femoral stem and 41 hips (35 patients, 19 males and 16 females) that underwent primary total hip arthroplasty using nonmodular femoral stems as a control. RESULTS: In all Ti-Ti cases, the mean Harris Hip Scores were 50.6 (range: 6-59) preoperatively and 92.7 (range: 78-99) at the last follow-up (P < 0.001). Regarding the neck component's modularity, straight neck components were used in all Ti-Ti cases, and an anteverted or a retroverted neck was not used in any case. Stem revision was performed in one hip due to aseptic loosening. One hip underwent open reduction and internal fixation due to periprosthetic fracture without stem loosening. There were no cases of osteolysis and periprosthetic joint infection and clinically detectable junctional problems. The stem survival rate, with any stem revision as the endpoint, at 12 years was 96.6%. No significant difference was observed in the functional and radiological outcomes beween the Ti-Ti and nonmodular groups. CONCLUSIONS: The Ti-Ti modular neck femoral stem had comparable results with broadly used nonmodular femoral stems; hence, it can be a reliable option in primary total hip arthroplasty. However, in terms of the modularity itself of the modular neck femoral stem, whether the modular neck femoral stem is useful in uncomplicated primary total hip arthroplasty is unclear.

Comparison of chromium and cobalt serum levels between a modular neck stem and its monoblock counterpart in primary total hip arthroplasty.

BACKGROUND: The addition of junctions in modular stems implies a greater susceptibility to corrosion. PURPOSE: The aim of this study is to compare serum chromium and cobalt levels after using a bimodular stem and its monoblock counterpart in primary total hip arthroplasty. Postoperative clinical scores were also compared. PATIENTS AND METHODS: A prospective cohort study between 2012 and 2015 was designed. One arm of the cohort included patients with the cementless modular neck stem H-Max M® and the other with the cementless monoblock stem counterpart H-Max S®. RESULTS: No statistically significant difference was found in chromium value between groups (p = 0.621) at two years postoperative. Cobalt value was higher in the modular group (p = < 0.001). No statistically significant difference was found in clinical postoperative scores except for the Harris Hip Score, with better results at six months in modular group (p = 0.007). CONCLUSIONS: Higher serum cobalt level in the modular group has limited the use of modular stems in our daily practice. Advantages of modular stem were not found. LEVEL OF EVIDENCE: II.

Cobalt Levels and Pseudotumor Characteristics Vary due to Metal Ion Source: Modular Femoral Neck vs Metal-on-Metal Articulations.

BACKGROUND: This study examines cobalt levels and pseudotumor characteristics in a non-recalled modular femoral prosthesis. We sought to determine relationships between serum cobalt levels and pseudotumors following modular and metal-on-metal (MoM) total hip arthroplasty (THA), the location and size of pseudotumors, and changes to pseudotumor grade over time. METHODS: We retrospectively evaluated a cohort of 190 primary THAs implanted with a dual-modular femoral stem by one surgeon from 2005 to 2013. One hundred seventeen THAs used a cobalt-chromium modular neck (CoCrMN) component and non-MoM articulation, 63 THAs had a titanium neck component and MoM articulation, and 10 had a titanium neck component and polyethylene liner. Serum ion levels were recorded for all patients. Pseudotumor grade and location were measured by musculoskeletal-trained radiologists. RESULTS: Cobalt levels did not correlate to time after index arthroplasty. In the CoCrMN group, cobalt levels were elevated in 11 of 19 (57.9%) patients with pseudotumor compared to 14 of 19 (73.7%) in the MoM group. Pseudotumors were more often located lateral to the hip joint in the CoCrMN group compared to anteromedial following MoM arthroplasty. In CoCrMN THAs, pseudotumors were visualized in 12 of 51 (23.5%) initial MARS MRIs within 40 months compared to 5 of 66 (7.6%) performed later (P = .02). CONCLUSION: Pseudotumor characteristics differ between patients with CoCrMN designs vs those with an MoM articulation. Normal serum cobalt levels did not exclude the presence of a pseudotumor and routine MARS MRI should be included in follow-up of patients with this CoCrMN prostheses.

Cementless ceramic-on-ceramic total hip arthroplasty in post-traumatic osteoarthritis after acetabular fracture: long-term results.

INTRODUCTION: Total hip arthroplasty (THA) is the standard procedure for post-traumatic osteoarthritis (OA) of the hip after acetabular fracture. However, it is not as simple as a primary THA, challenging the surgeon with anatomical deformity and intra and postoperative complications. In the current literature, there is a lack of studies reporting long-term results. May ceramic-on-ceramic (CoC) bearings provide good clinical and radiological outcomes at a long-term follow-up in patients undergoing THA following acetabular fracture? MATERIALS AND METHODS: We retrospectively analyzed 68 patients (mean age 47 years [range 22-75)] who underwent cementless modular neck stem THA, all implants CoC bearings (50 previously operatively treated and 18 non-operatively treated) after a specific CT study protocol at our Institute since 2000-2008. Clinical outcomes, prosthetic components' osseointegration, survival rate, and reasons for revision were analyzed. Minimum clinical and radiological follow-up was 10 years. RESULTS: HHS improved significantly after surgery from 37.6 ± 14.1 to 88.4 ± 11.6. 8 revision surgeries were performed, none for infection: we reported 2 stem aseptic loosening, 2 periprosthetic femoral fractures and 4 modular neck fractures. One implant noise (third-generation ceramic coupling) was described. Cup osseointegration was present (according to Moore the presence of at least 3 radiological criteria defines an effective osseointegration) in 67 patients (98.5%). After a 10 years follow-up, survival rate resulted 88.4%, sensibly higher than most of results reported in the current literature. CONCLUSION: The high survival rate may be related to CoC: no osteolysis and no infections were reported. Also acetabular cup loosening incidence was sensibly lower (1.47%) among loosening rate described by other authors. Clinical and radiological outcomes were decent, probably due to modular prosthesis design. Modular necks are a solution which can help achieving a proper functional reconstruction of the hip (offset, center of rotation), but should be avoided in young and overweight patients because of the high risk of fracture. CoC bearings in THAs in post-traumatic OA after acetabular fracture showed good results despite the fact that specific ceramic-related issues have to be considered.

Effect of a modular neck hip prosthesis on anteversion and hip rotation in total hip arthroplasty for developmental dysplasia of the hip.

Total hip arthroplasty (THA) is often required to decrease the excessive anatomical femoral anteversion (AA) in developmental dysplasia of the hip. Studies have recommended decreasing the AA via the use of a retroverted modular neck. However, hip rotation after THA may strengthen or weaken the effect of changing the AA. Thus, the present study analyzed the effect of a retroverted neck on AA and hip rotation. Patients who underwent THA using a straight neck (ST group) or a 15° retroverted neck (RV group) in a version changeable dual modular system (Mainstay stem, Kyocera, Kyoto, Japan) were retrospectively reviewed. After matching for age, body mass index, and surgical approach, 44 patients were included in each group. The AA and hip rotation (femoral rotational angle: FRA) were measured on CT images acquired preoperatively and 1 month after THA, and were compared between the groups. The mean ± standard deviation preoperative AA of the ST group (26.1 ± 10.7°) was significantly smaller than that of the RV group (44.2 ± 7.8°) (p < 0.001). In contrast, the postoperative AA did not significantly differ between the groups (ST group 27.5 ± 9.8°, RV group 25.1 ± 8.3°, p = 0.406). The change in FRA after THA did not significantly differ between the groups (ST group - 3.8 ± 9.9°, RV group - 3.5 ± 9.1°, p = 0.841). In conclusion, a 15° retroverted neck was useful in controlling AA in hips with excessive AA, and the change in FRA after THA did not differ between the ST group and the RV group.

Patients With Modular-Neck Total Hip Arthroplasty: A Brief Five-Year Follow-Up Study.

BACKGROUND: We have previously reported the early clinical results of a modular-neck stem identifying an early 2-year revision rate of 13% due to neck-stem corrosion. This report updates our findings to a midterm mean follow-up of 5 years. METHODS: This is a consecutive retrospective review of 186 modular-neck hips in 175 patients with a mean follow-up period was 60.1 ± 22.9 months (range 24-100). We reviewed clinical findings, routine radiographs, detailed imaging (metal artifact reduction software-magnetic resonance imaging, ultrasound), and serum ion levels of cobalt and chromium. We performed a survival analysis with the endpoint defined as revision total hip arthroplasty due to neck-stem corrosion. RESULTS: We revised 41 hips (22.0%) for neck-stem corrosion. Clinical symptoms (groin pain ± local swelling) were consistently present in those that came for revision. Mean serum cobalt ion levels increased as time passed in all patients. Detailed image findings showed that larger fluid collections and local soft tissue masses were seen predominately in symptomatic patients. However, 14% of patients who underwent revision did not have positive magnetic resonance imaging or ultrasound findings. The survival rate was 87% (95% confidence interval 81-92) at 3 years postoperatively and 72% (95% confidence interval 64-80) at 7 years postoperatively. CONCLUSION: The revision rate for this modular-neck stem due to neck-stem corrosion at mid-term follow-up almost doubled in comparison to previous short-term results. It seems reasonable to consider clinical follow-up alone as symptoms, rather than blood testing for ion levels, seem to be the defining characteristic of failure.

High Failure at a Minimum 5-Year Follow-Up in Primary Total Hip Arthroplasty Using a Modular Femoral Trunnion.

BACKGROUND: Modular femoral trunnions enable the surgeon to independently adjust offset, leg length, and anteversion in total hip arthroplasty (THA). However, modularity may result in an increased risk of fretting and corrosion along with a higher risk of implant dissociation or fracture. The purpose of this study is to evaluate mid-term survivorship of THAs using a cementless modular system. METHODS: A consecutive series of 221 patients who underwent a primary THA using the ALFA II modular stem by a single surgeon between 2002 and 2004 were reviewed. Survivorship of the ALFA II modular hip system was evaluated at a minimum of 5 years postoperatively. RESULTS: Of the 221 patients, 28 (12.7%) died from causes unrelated to the surgery before adequate follow-up, and 64 (29.0%) patients were lost to follow-up. The remaining 129 patients had a mean 6.5-year (range: 5-8 years) follow-up. All-cause survivorship of the modular stem system was 81% (95% confidence interval = 69-90) at a mean 6.5-year follow-up. Of the 25 (19.4%) cases requiring revision surgery, 52.0% was for dissociation of the modular components, 32.0% was for fracture of the prosthesis, 12.0% was for instability/multiple dislocations, and 4.0% was for chronic septic THA. Body mass index (odds ratio = 1.080) and offset (odds ratio = 1.254) were independent risk factors for mechanical failures of the modular stem system. CONCLUSION: The modular stem hip system of interest in this study demonstrates a high failure rate at mid-term follow-up, and we caution against the use of similar designs in primary THAs.

Cementless modular neck stems: are they a safe option in primary total hip arthroplasty?

PURPOSE: The objective was to assess aseptic complications and functional outcome using a primary total hip arthroplasty with modular neck. METHODS: Prospective cohort of 317 consecutive patients. The mean age was 61.1 (range, 41-84) years. The H-Max-M model (Lima, Italy) system was used in all patients. The functional assessment was made by the Harris Hip Score, Short Form-36 (SF-36), Western Ontario and McMaster Universities Osteoarthritis Index and visual analogue scale for pain. Radiological outcomes were also assessed, and adverse events and complications were noted. RESULTS: The mean follow-up was 6.1 (range, 2-8) years. Functional outcome significantly improved in most patients. There were 3 deep infections (0.9%) and 17 aseptic complications (5.3%) including 1 intraoperative acetabular fracture, 3 later periprosthetic femoral fractures, 1 broken ceramic insert, 1 acetabular loosening, 3 femoral loosening and 1 broken titanium modular neck in a obese patient. No pseudotumors or elevated serum levels of metal ions were found among the patients with radiolucent lines or aseptic loosening. CONCLUSIONS: The findings in the present study showed that the H-MAX-M stem provided satisfactory functional outcome in most patients with a low rate of complications attributable to the modular neck design. We consider that using this novel modular neck-stem coupling design can be an alternative to the conventional monoblock stems in patients without overweight.

Nano-analyses of wear particles from metal-on-metal and non-metal-on-metal dual modular neck hip arthroplasty.

Increased failure rates due to metallic wear particle-associated adverse local tissue reactions (ALTR) is a significant clinical problem in resurfacing and total hip arthroplasty. Retrieved periprosthetic tissue of 53 cases with corrosion/conventional metallic wear particles from 285 revision operations for ALTR was selected for nano-analyses. Three major classes of hip implants associated with ALTR, metal-on-metal hip resurfacing arthroplasty (MoM HRA) and large head total hip replacement (MoM LHTHA) and non-metal-on-metal dual modular neck total hip replacement (Non-MoM DMNTHA) were included. The size, shape, distribution, element composition, and crystal structure of the metal particles were analyzed by conventional histological examination and electron microscopy with analytic tools of 2D X-ray energy dispersive spectrometry and X-ray diffraction. Distinct differences in size, shape, and element composition of the metallic particles were detected in each implant class which correlate with the histological features of severity of ALTR and variability in implant performance.

Modular Neck vs Nonmodular Femoral Stems in Total Hip Arthroplasty-Clinical Outcome, Metal Ion Levels, and Radiologic Findings.

BACKGROUND: Modular neck femoral stem (MNFS) for total hip arthroplasty (THA) was introduced to optimize the outcome, but created concerns about pain, elevated blood metal ion levels, and adverse reaction to metal debris such as pseudotumors (PTs), related to corrosion between femoral neck and stem. We compared these outcomes in patients with MNFS or nonmodular femoral stem (NFS) THA. METHODS: Thirty-three patients with unilateral MNFS THA were compared with 30 patients with unilateral NFS THA. Levels of pain, serum cobalt, serum chromium were determined. Magnetic resonance imaging was performed to describe PT and fatty atrophy of muscles. RESULTS: The MNFS and NFS group had a mean follow-up of 2.3 and 3.1 years, respectively. Four and 13 patients in the MNFS and NFS group had pain, respectively (P = .005). The MNFS group had higher levels of serum cobalt (P < .0001) and chromium (P = .006). PTs were present in both the MNFS (n = 15) and NFS (n = 7) groups (P = .066). PTs were related to serum cobalt (P = .04) but not to pain or serum chromium. Fatty atrophy prevalence in the piriformis and gluteal muscles were higher in patients with MNFS (P = .009 and P = .032, respectively). CONCLUSION: More patients in the NFS group had pain. Serum cobalt and chromium levels were higher in the MNFS group. Prevalence of PTs was twice as high in the MNFS group, but the difference was insignificant.

Retrieval Analysis of Neck-Stem Coupling in Modular Hip Prostheses.

BACKGROUND: Dual-taper modular stems have suffered from high revision rates caused by adverse local tissue reactions secondary to fretting and corrosion. We compared the fretting and corrosion behavior of a group of modular neck designs to that of a design that had been recalled for risks associated with fretting and corrosion at the modular neck junction. METHODS: We previously analyzed fretting and corrosion on 60 retrieved Rejuvenate modular neck-stem implants. Here we compare those results to results from 26 retrieved implants from 7 other modular neck designs. For the 26 additional cases, histology slides of tissue collected at revision were reviewed and graded for aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Multivariate analyses were performed to assess differences in fretting and corrosion, adjusting for confounding factors (eg, length of implantation). RESULTS: The Rejuvenate design had higher damage and corrosion scores than the other 7 designs (P < .01). Histologic samples from the recalled design were 20 times more likely to show ALVAL than samples from the other designs (P < .01). Mixed metal couples had higher fretting (P < .01) and corrosion (P = .02) scores than non-mixed metal couples. CONCLUSION: Fretting and corrosion occurred on all modular neck-stem retrievals regardless of design. However, mixed metal couples suffered more corrosion than homogenous couples. This may be due to the lower modulus of the titanium alloy used for the stem, allowing for increased metal transfer and surface damage when loaded against a cobalt alloy modular neck, which in turn could account for the higher ALVAL and corrosion scores. Due to increased corrosion risk with mixed metals and increased neck fracture risk with non-mixed metal stem and necks, we suggest that clinicians avoid implantation of modular neck-stem systems.

A Single-Center Experience With a Titanium Modular Neck Total Hip Arthroplasty.

BACKGROUND: Added modular junction has been associated with implant-related failures. We report our experience with a titanium-titanium modular neck-stem interface to assess complications, possible clinical factors influencing use of neck modularity, and whether modularity reduced the incidence of dislocation. METHODS: A total of 809 total hip arthroplasties completed between 2005 and 2012 from a prospectively collected database were reviewed. The mean follow-up interval was 5.7 years (3.3-10.3 years). Forty-five percent were male (360 of 809), and 55% were female (449 of 809). All stems were uncemented PROFEMUR TL (titanium, flat-tapered, wedge) or PROFEMUR Z (titanium, rectangular, dual-tapered) with a titanium neck. RESULTS: Increased modularity (anteverted/retroverted and anteverted/retroverted varus/valgus (anteverted/retroverted + anteverted/retroverted varus/valgus) was used in 39.4% (135 of 343) of cases using the posterior approach compared with 6.8% (20 of 293) of anterior and 23.7% (41 of 173) of lateral approaches. Four males sustained neck fractures at a mean of 95.5 months (69.3-115.6 months) after primary surgery. Overall dislocation rate was 1.1% (9 of 809). The posterior approach had both the highest utilization of increased modularity and the highest dislocation rate (2.3%), of which the most were recurrent. The anterior (0.3%) and lateral (0%) approaches had lower dislocation rates with no recurrences. CONCLUSION: At a mean 5.7 years, our experience demonstrates a low neck fracture (0.5%) and a low dislocation rate (1.1%). Use of increased modularity may not improve dislocation risk for the posterior approach. Continued surveillance of this group will be necessary to determine long term survivorship of this modular titanium implant.

Systemic Metal Ion Levels in Patients With Modular-Neck Stems: A Prospective Cohort Study.

BACKGROUND: Recent registry data reveal that modular-neck hip prostheses are associated with increased revision rates compared to fixed-neck stems. Poor implant survival has been associated to corrosion at the neck-stem junction, inducing metal ion release and subsequently adverse local tissue reactions. Data on metal ion release on the neck-stem junction of such stems are scarce. The purpose of this study was to evaluate corrosion at this interface by determining metal ion release. METHODS: Serum and whole blood metal ion levels of 40 patients after 1 year of implantation of a modular-neck stem (titanium stem and cobalt-chromium neck) were compared with 10 patients with a monobloc version of the stem (all titanium) and 10 patients having no implant at all. RESULTS: Seven of 40 patients (18%) with a modular-neck stem had cobalt or chromium concentrations >2 µg/L. These patients underwent magnetic resonance imaging using metal artifact reduction sequences, which revealed a pseudotumor in 1 patient. CONCLUSION: Corrosion at the neck-stem junction of modular-neck stems is a reported phenomenon, which is in part reflected by elevated systemic ion levels. The use of such implants should be restricted to a minimum, and screening algorithms of patients with such implants must be developed.

"Top-Out" Removal of Well-Fixed Dual-Taper Femoral Stems: Surgical Technique and Radiographic Risk Factors.

BACKGROUND: Contemporary "dual-taper" modular femoral neck-stem designs have been associated with taper corrosion-related adverse local tissue reaction (ALTR) requiring revision surgery and stem removal. Extended trochanteric osteotomy is recognized as the workhorse procedure for revision hip surgery. The aim of our study is to describe our "top-out" stem removal surgical technique and identify preoperative radiographic risk factors associated with periprosthetic fractures when using this technique. METHODS: This is a single-center, single-surgeon, retrospective case series. Operative and clinic records were reviewed for patients with dual-taper modular femoral neck-stem junction who underwent revision surgery for taper tribocorrosion-related ALTR. RESULTS: Eighty-three patients (36 men and 47 women; mean age, 61.8 ± 10.3; body mass index, 30.2 ± 8.6) were revised using the top-out technique. Significant improvements in postoperative Harris hip score (P = .004), EuroQol 5-dimension questionnaire (EQ-5D; P < .001), and EQ-5D US-adjusted scores (P < .001) were observed at 19-months follow-up. Our study reports periprosthetic fracture incidence of 14% and reoperation rate of 7%. Periprosthetic fractures were positively correlated with radiographic parameters such as overhang distance (R = 0.376; P = .002) and overhang ratio (R = 0.312; P = .01) and negatively correlated with radiographic implant medial calcar prominence (R = -0.299; P = .01). CONCLUSION: Removal of well-fixed femoral components can be challenging, and the burden of revision surgery for taper tribocorrosion-related ALTR of these femoral stems is likely to rise. A top-out technique with systematic preoperative planning with radiographs provides a viable, alternative surgical option to remove well-fixed femoral component while preserving the femoral bony envelope.

Correlation of corrosion and biomechanics in the retrieval of a single modular neck total hip arthroplasty design: modular neck total hip arthroplasty system.

Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for local pseudotumor and metallosis formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (SCANNING ELECTRON MICROSCOPY) assessment was done and correlated with FEA (finite element analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk.

Short-Term Metal Ion Trends Following Removal of Recalled Modular Neck Femoral Stems.

Elevated serum metal ions have been well documented with the Rejuvenate modular neck femoral stem (Stryker, Mahwah, NJ); however, the rate at which ion levels decline following revision is less clear. This study included fifty-nine consecutive revisions of Rejuvenate stems for symptomatic ALTR. Blood tests prior to revision and postoperatively at 6weeks, 3months, 6months, and 1year measured serum cobalt and chromium concentrations, ESR, and CRP. At six weeks following revision of a unilateral Rejuvenate, cobalt and chromium levels dropped from preoperative levels by 67% and 42%, respectively. At three months, cobalt levels declined to 19% of preoperative values, but chromium levels remained stable. With this information, surgeons can set realistic expectations for serum metal ion levels following Rejuvenate stem revision.

Corrosion and Fretting of a Modular Hip System: A Retrieval Analysis of 60 Rejuvenate Stems.

Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.

Revision of Recalled Modular Neck Rejuvenate and ABG Femoral Implants.

Modular neck femoral stems have been associated with adverse local tissue reactions (ALTR), leading to a voluntary recall, but these effects have not been well-characterized. A retrospective review of intraoperative findings and cobalt/chromium levels was performed in 103 hips undergoing revision for ALTR. The average preoperative serum cobalt level was 7.6 µg/L (range 1.1-23 µg/L) and chromium level was 1.8 µg/L (range 0.1-6.8 µg/L). Metallic sludge was noted in 100%, synovitis in 98%, pericapsular rind in 82%, and calcar erosion in 85%. An osteotomy was required for removal in 44%. We concluded that revision of modular neck femoral stems is associated with increased preoperative metal ion levels and stem-neck corrosion. Despite advanced stem explantation techniques, osteotomy was frequently required, leading to increased morbidity.

MRI Findings Associated with Recalled Modular Femoral Neck Rejuvenate and ABG Implants.

MARS-MRI is suggested for the diagnosis of adverse local tissue reactions (ALTR) in patients with recalled femoral stems with modular necks, but there has been no major study looking at MARS-MRI findings in this population. A retrospective review was performed on 312 patients who received a modular neck hip implant between October 2007 and February 2012. 62% of patients had intra-articular effusions, with 27% containing debris. Extra-capsular effusions were present in 35% of hips. 54% had synovitis and 5.4% had osteolysis. Tendinopathy and tendon disruption was present in the gluteus medius (58%/12%), hamstring (56%/12%), gluteus minimus (38%/7.7%) and iliopsoas (7.1%/4.8%). Abnormal MARS-MRI findings are associated with modular neck femoral components and can suggest underlying ALTR. MARS-MRI abnormalities merit serious consideration in this population.

Corrosion behavior of tantalum-coated cobalt-chromium modular necks compared to titanium modular necks in a simulator test.

This study compared the corrosion behavior of tantalum-coated cobalt-chromium modular necks with that of titanium alloy modular necks at their junction to titanium-alloy femoral stem. Tests were performed in a dry assembly and two wet assemblies, one contaminated with calf serum and the other contaminated with calf serum and bone particles. Whereas the titanium modular neck tested in the dry assembly showed no signs of corrosion, the titanium modular necks tested in both wet assemblies showed marked depositions and corrosive attacks. By contrast, the tantalum-coated cobalt-chromium modular necks showed no traces of corrosion or chemical attack in any of the three assemblies. This study confirms the protective effect of tantalum coating the taper region of cobalt-chromium modular neck components, suggesting that the use of tantalum may reduce the risk of implant failure due to corrosion.