Fracture of contemporary femoral stems is a rare occurrence. Earlier THR stems failed due to design issues or post manufacturing heat treatments that weakened the core metal. Our group identified and analyzed 4 contemporary fractured femoral stems after revision surgery in which electrochemical welds contributed to the failure.

All four stems were proximally porous coated titanium alloy components. All failures occurred in the neck region post revision surgery in an acetabular cup exchange. All were men and obese. The fractures occurred at an average of 3.6 years post THR redo (range, 1.0–6.5 years) and 8.3 years post index surgery (range, 5.5–12.0 years). To demonstrate the effect of electrocautery on retained femoral stems following revision surgery, we applied intermittent electrosurgical currents at three intensities (30, 60, 90 watts) to the polished neck surface of a titanium alloy stem under dry conditions.

At all power settings, visible discoloration and damage to the polished neck surface was observed. The localized patterns and altered metal surface features exhibited were like the electrosurgically-induced damage priorly reported.

The neck regions of all components studied displayed extensive mechanical and/or electrocautery damage in the area of fracture initiation. The use of mechanical instruments and electrocautery was documented to remove tissues in all 4 cases.

The combination of mechanical and electrocautery damage to the femoral neck and stem served as an initiation point and stress riser for subsequent fractures. The electrocautery and mechanical damage across the fracture site observed occurred iatrogenically during revision surgery. The notch effect, particularly in titanium alloys, due to mechanical and/or electrocautery damage, further reduced the fatigue strength at the fractured femoral necks. While electrocautery and mechanical dissection is often required during revision THA, these failures highlight the need for caution during this step of the procedure in cases where the femoral stem is retained.

In health care, several studies have suggested worse outcomes in African-Americans. Our objective was to study the relationships of race with outcomes in a series of total hip arthroplasty (THA) cases.

A consecutive series of 2,435 total hip/knee arthroplasties (primaries and revisions) performed in a single hospital by a single surgeon were studied. Revisions due to infections were excluded. Data on race was available for 718 THAs which were finally included. Cases of African-Americans (AA) (n=55) and Whites (n=663) were compared on baseline demographics, Charlson, ASA, preoperative-diagnosis; preoperative and postoperative pain intensity/frequency visual-analogue-scale, QWB-7, SF-36, WOMAC, Hip Harris, Postel-D'Aubigne scores; and on postoperative transfusion rates. T-tests, Chi-Square, MANCOVA (age, ethnicity, BMI, and preoperative-diagnosis adjustments) were used. Mean follow-up: 3 years. Alpha was set at 0.05.

At baseline and compared to Whites, African-Americans were significantly younger (mean, 67 vs. 59 years), had fewer Hispanics (61% vs. 26%), and had higher BMI (28.5 vs. 30.6 Kg/m²) (all p≤0.048), respectively. Preoperative diagnoses were significantly different (p<0.001). There were no significant differences between the groups on preoperative scores after adjusting for confounders. Postoperatively, SF-36 bodily-pain (70 vs. 57), SF-36 mental-component-summary (56 vs. 53), WOMAC-total (5 vs. 12), and WOMAC-stiffness (0.14 vs. 0.57) were significantly worse in African-Americans (all p≤0.043), respectively. African-Americans underwent more transfusions (28% vs. 65%, p=0.001).

Compared to Whites, African-Americans underwent THA earlier in life, with higher BMI, and different preoperative-diagnosis. They also had worse postoperative scores and more transfusions. Race seems to be strongly associated with outcomes.

INTRODUCTION

Computer navigation has been shown to decrease the variance of component positioning in primary THR. The cost of a navigation system in the U.S. however can exceed $200,000 in capital costs and $300–850 a case for disposables. Our objective was to assess the cost-utility of a hip navigation system.