Sensitivity and Specificity of Metal Ion Levels in Predicting "Pseudotumors" due to Taper Corrosion in Patients With Dual Taper Modular Total Hip Arthroplasty.

BACKGROUND: Currently, no serum metal ion threshold exists to identify adverse tissue reactions in total hip arthroplasty (THA) patients with taper corrosion. Our study aims to investigate the sensitivity and specificity of serum metal ions in detecting taper corrosion related pseudotumors in patients with dual taper modular THA. METHODS: A total of 148 patients with dual taper modular THA were investigated: (1) 90 patients with pseudotumors detected with metal artifact reduction sequence-magnetic resonance imaging (MARS-MRI) and (2) 58 patients without pseudotumors on MARS-MRI. Receiver operating characteristic curves were constructed to determine the sensitivity and specificity using different metal ion thresholds. The severity of intraoperative tissue damage was correlated with preoperative metal ion levels. RESULTS: Pseudotumor was associated with higher cobalt (5.0 µg/L vs 3.7 µg/L, P < .01) and Co/Cr ratio (6.0 vs 3.7, P < .01). The sensitivity and specificity for cobalt level of 2.8 µg/L and Co/Cr ratio of 3.8 in detecting taper corrosion-related pseudotumors on MARS-MRI was 88% and 32% and 70% and 50%, respectively. Higher intraoperative tissue damage grades demonstrated significantly higher Co/Cr ratios (8.6 vs 3.4, P = .03). CONCLUSION: Although metal ion levels alone should not be relied on as the sole parameter to determine revision surgery, cobalt level >2.8 µg/L and the Co/Cr ratio >3.8 are useful clinical diagnostic adjuncts in the systematic clinical evaluation for taper corrosion-related adverse tissue reactions in patients with dual modular taper THA.

Utility of Serum Inflammatory and Synovial Fluid Counts in the Diagnosis of Infection in Taper Corrosion of Dual Taper Modular Stems.

BACKGROUND: An accurate diagnosis of periprosthetic joint infection (PJI) is critical as treatment of the infected total hip arthroplasty differs from aseptic failure. The clinical presentation of PJI may mimic symptoms of taper corrosion. Our aim was to evaluate the utility of serum inflammatory markers and synovial fluid white blood cell (WBC)/differential counts in diagnosis of PJI in failed dual taper total hip arthroplasty due to taper corrosion. METHODS: We retrospectively reviewed 62 dual taper modular stem patients who underwent revision surgery for symptomatic adverse local tissue reaction due to taper corrosion. All patients had preoperative hip synovial aspirations, serum inflammatory markers, metal ion levels, and intraoperative cultures. Using Musculoskeletal Infection Society PJI criteria, we divided the cohort into infected and noninfected groups. Receiver-operating characteristic curves were constructed to determine the relationship and optimal cutoff values for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and synovial fluid counts. RESULTS: Infection group had significantly higher mean ESR (P = .002), CRP (P = .01), synovial fluid WBC (P < .001), and neutrophil percentage (P = .02). Cobalt levels were significantly elevated in noninfection group (P = .02). Using receiver-operating characteristic curve analysis, the most ideal tests for diagnosis of PJI were synovial fluid WBC (area under the curve = 86%, optimal cutoff 730 WBC/uL) and neutrophil percentage (area under the curve = 83%, optimal cutoff 65%). ESR and CRP thresholds of 22 mm/h and 3 mg/L demonstrated 57% sensitivity and 95% specificity and 29% sensitivity and 93% specificity for detection of PJI, respectively. CONCLUSION: Our study suggests that ESR and CRP are useful in excluding PJI in dual taper modular implants with corrosion, whereas both synovial WBC count and neutrophil percentage are useful markers for diagnosing infection.

Early Outcomes of Revision Surgery for Taper Corrosion of Dual Taper Total Hip Arthroplasty in 187 Patients.

BACKGROUND: Modular dual taper femoral neck designs have been associated with taper corrosion requiring revision surgery. However, outcomes after revision dual taper total hip arthroplasty in patients with symptomatic adverse local tissue reaction due to taper corrosion remain largely unknown. METHODS: A total of 198 revision surgeries in 187 patients with dual taper femoral stem total hip arthroplasty with minimum 12-month follow-up were evaluated. RESULTS: At mean follow-up of 18 months, at least 1 complication had occurred in 39 patients (20%) of 198 revisions. Single episode of dislocation, treated with close reduction, occurred in 16, whereas 2 patients required rerevision due to multiple dislocations. Infection requiring rerevision occurred in 3 patients. Adverse local tissue reaction recurrence requiring reoperation occurred in 6 patients. Implant survivorship for revision for any cause was 86% at 30 months. The reoperation rate of revised dual taper was 8% (16 out of 198 hips). The median serum levels of cobalt, chromium, and cobalt/chromium ratio decreased (P < .01) from 5.3 µg/L (range: 2.3-48.5 µg/L), 2.6 µg/L (range: 0.2-64 µg/L), and 4.7 (range: 2.1-35) prerevision to 1.4 µg/L (range: 0.2-8.8 µg/L), 0.7 µg/L (range: 0.1-3.9 µg/L), and 2.2 (range: 0.4-8.8) postrevision, respectively. CONCLUSION: This pilot study demonstrates that intraoperative tissue necrosis was associated with a high rate of early complications (20%) and revisions (8%), suggesting the importance of a systematic evaluation of these patients including metal ion levels and metal artifact reduction sequence magnetic resonance imaging in optimizing revision outcome, as early diagnosis will facilitate the initiation of appropriate treatment before significant adverse tissue necrosis.

A Systematic Literature Review of Three Modalities in Technologically Assisted TKA.

In effort to reduce the revision burden of total knee arthroplasty (TKA), industry emphasis has focused on replacing manual techniques-which are subject to variability-with technological implements. Unfortunately, technological innovation often continues before adequate time for critical evaluation has passed. Therefore, the purpose of this descriptive literature review was to collect a large sample of international data and report on the clinical and economic efficacy of three major types of technologically assisted TKA: navigation, patient-specific instrumentation, and sensorized trials.

The effect of preoperative planning and impaction grafting surgical technique on intraoperative and postoperative complication rate for femoral revision patients with moderate to severe bone loss mean 4.7-year results.

This study reports the results of 41 revision hips, implanted by a single surgeon using impaction grafting (mean follow-up, 4.7 years). All hips had Paprosky scores of III or IV. Harris hip scores improved from 43 to 82. There was 1 intraoperative and 2 postoperative fractures. A single stem was revised during the study. Radiographic review showed the 40 unrevised stems to be stable, and graft incorporation was seen in at least 1 zone in 100% of the femurs. There was no stem subsidence greater than 2.5 mm. The results of this study demonstrate that preoperative planning and a surgical technique, which emphasizes femoral support and vigorous impaction grafting, resulted in an acceptable incidence of complications.