High Incidence of Mechanically Assisted Crevice Corrosion at 10 Years in Non-Cemented, Non-Recalled, Contemporary Total Hip Arthroplasties

BACKGROUND

One percent to 3% of contemporary non-cemented total hip arthroplasties (THAs) present with symptomatic mechanically assisted crevice corrosion (MACC). The incidence of this problem, however, as well as the rate of asymptomatic elevations in serum cobalt, is unknown.

METHODS

Cobalt and chromium levels were obtained in conjunction with radiographs at routine 10-year surveillance follow-up of THAs from a single manufacturer with a titanium stem, cobalt alloy femoral head, and cross-linked polyethylene countersurface.

RESULTS

Ten-year follow-up of patients with 162 consecutive THAs revealed that 17 patients with 18 hips had died of unrelated causes prior to metal ion testing. Two hips were revised for other reasons, and of the remaining 142 hips, 33 were in patients who were lost, leaving 109 hips (77% of those in alive patients and unrevised for other reasons and 67% of the entire cohort) for investigation. Sixty-three patients (58%) had a serum cobalt less than 1 ppb, and 35 (32%) a cobalt of ≥1 ppb, a cutoff consistent with MACC. Of the 32 hips with definite MACC, 15 of 32 (47%) patients were symptomatic, 16 of 30 (53%) patients had adverse local tissue reaction on magnetic resonance imaging, and 19 of 32 (59%) patients have undergone revision surgery for MACC to date.

CONCLUSION

At 10-year follow-up, a minimum of 22% (35/162) of hips had a cobalt level more than 1 ppb, consistent with MACC. Symptoms and adverse local tissue reactions are each present about one-half of the time, and 59% of those with documented MACC have undergone revision.

Standardizing terms for tribocorrosion-associated adverse local tissue reaction in total hip arthroplasty

Recognizing and adopting standardized terms for adverse local tissue reaction associated with tribocorrosion in total hip arthroplasty are essential for clear scientific discourse and clinical communication. Our goal was to develop terms that can be broadly applied to characterize the local tissue response to tribocorrosion debris, based on current evidence regarding the etiology of this failure mode and its consequences. The proposed standardized terms will improve the understanding and interpretation of analytical tests, advance diagnostic and treatment algorithms, and reduce confusion in research by maintaining consistent nomenclature.

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

BACKGROUND

Gross 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.

METHODS

We 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.

RESULTS

In 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.

CONCLUSION

In 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.

Comparison of Pre-Revision Magnetic Resonance Imaging and Operative Findings in Mechanically Assisted Crevice Corrosion in Symptomatic Metal-on-Polyethylene Total Hip Arthroplasties

BACKGROUND

Failed total hip arthroplasty (THA) caused by mechanically assisted crevice corrosion (MACC) has serious consequences-notably, adverse local tissue reactions. Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been used to evaluate failed THA for other reasons but has not been assessed for the analysis of cases of MACC in the setting of metal-on-polyethylene arthroplasties.

METHODS

We examined the correlation between preoperative MARS MRI and surgical findings in a cohort of 20 consecutive patients undergoing revision THA for symptomatic MACC without other associated orthopedic diagnoses. Surgical findings included soft tissue and bone evaluation, presence and location of fluid, abductor disruption, composite tissue damage grade, and prosthesis trunnion damage at the time of revision.

RESULTS

MARS MRI complex synovitis, thickened pseudocapsule, and extra-articular fluid extension each strongly correlated with both the soft-tissue damage grade and trunnion damage noted at surgery. Bone marrow edema was also found to strongly correlate with bone necrosis intraoperatively.

CONCLUSION

MARS MRI is an excellent diagnostic tool for evaluation of patients with elevated serum Co after metal-on-polyethylene THA. Patients with complex synovitis, a thick pseudocapsule, bone marrow edema, and extra-articular fluid should strongly consider revision surgery.

Usefulness of ultrasonography for detection of pseudotumors after metal-on-metal total hip arthroplasty

We retrospectively analyzed 83 metal-on-metal total hip arthroplasties in 74 patients. Ultrasonography and magnetic resonance imaging (MRI) of each hip were performed to detect abnormal patterns and pseudotumors. We examined the reliability of ultrasonography for detecting pseudotumors in comparison with MRI. We also compared the acetabular component inclination between patients with and without pseudotumors. The mean positive and negative predictive values for pseudotumor detection by ultrasonography were 65% and 91%, respectively. The mean positive and negative likelihood ratios were 5.78 and 0.32, respectively. There was no clear association between pseudotumor presence and acetabular component inclination. We concluded that ultrasonography is a suitable technique to screen for the presence of pseudotumors. We also need to distinguish between bearing-related and taper junction corrosion-related complications.