Read Complete Study Here:  https://surfacehippy.info/pdf/dr-gross-2023-20year-survivorship-study.pdf

Abstract

Background At the turn of the century, over one‑third of total hip arthroplasties comprised metal‑on‑metal bear‑
ings. As this patient population and their implants age, it is crucial to understand associated late failure modes
and expected long‑term functional outcomes. We report the long‑term results of a large metal‑on‑metal unce‑
mented total hip arthroplasty system with unique design characteristics compared to others that have been reported
with high failure rates.

Methods We retrospectively analyze our prospective clinical database to determine overall implant survivorship
and functional outcomes. Further, we compare these results to the clinical outcomes reported in orthopedic registries
and in other published studies with similar metal‑on‑metal total hip arthroplasty cohorts.

Results Implant survivorship at 10 years was 99.1% and continued to 97.6% survivorship at 20 years. Implant sur‑
vivorship at 20 years did not vary significantly between sexes (Male: 98.3%, Female: 97.2%; log‑rank p‑value = 0.46).
Mean whole blood cobalt levels were 2.6 μg/L in unilateral cases, 5.3 μg/L in bilateral patients, and 3.4 μg/L
for the combined cohort. Average blood chromium levels were 1.4 μg/L in unilateral patients, 2.9 μg/L in bilateral
patients, and 1.8 μg/L for group combined. We observed a 0.9% rate of failure due trunnion corrosion at a mean
of 13.1 years postoperatively (10.6–15.6 years) but had no bearing wear failures.

Conclusions Our 20‑year implant survivorship of 97.6% with the M2a‑38 bearing surpassed registry benchmarks
for THA. This large‑bearing (38 mm), full hemisphere coverage metal‑on‑metal system had no bearing wear failures,
one failure of instability, one failure of fixation, and three trunnion failures, perhaps suggesting an optimum balance
between stability of the joint and the trunnion.