Trial results for the Pinnacle RSA Study, investigating acetabular shell migration in patients with osteoarthritis, were posted on ClinicalTrials.gov on 2025-10-21, reporting an overall mean superior cup migration of 0.055 mm at 2 years post-implantation.
Background
Osteoarthritis and degenerative arthritis are common conditions often requiring total hip arthroplasty. The stability of the acetabular component (cup) is crucial for implant longevity. Superior cup migration, or subsidence, indicates micromotion and potential loosening. Radiostereometric Analysis (RSA) precisely measures these small implant movements, providing vital data for assessing performance.
Trial design
This Phase NA study, which was terminated, enrolled 100 participants with Osteoarthritis and Degenerative Arthritis. The primary objective was to establish the mean superior cup migration of the Pinnacle Acetabular Shell using model-based RSA over two years post-implantation. The primary endpoint was the mean vertical subsidence (superior cup migration) at 2 years, measured with RSA, summarized for each surgical approach and combined.
Key results
The trial reported key measurements for superior cup migration (subsidence) of the Pinnacle Acetabular Shell:
- Mean Superior Cup Migration (Subsidence) at 6 Week and 2 Years:
- For the Posterior Approach, the mean was -0.001 mm (Standard Deviation 0.065 mm).
- For the Lateral Approach, the mean was -0.03 mm (Standard Deviation 0.094 mm).
- For the Anterior Approach, the mean was -0.036 mm (Standard Deviation 0.133 mm).
- For the Overall Population, the mean was -0.02 mm (Standard Deviation 0.099 mm).
- Another measurement for the Posterior Approach showed a mean of 0.06 mm (Standard Deviation 0.292 mm).
- Another measurement for the Lateral Approach showed a mean of 0.045 mm (Standard Deviation 0.501 mm).
- Another measurement for the Overall Population showed a mean of 0.055 mm (Standard Deviation 0.362 mm).
- RSA Measured Subsidence of the Pinnacle Acetabular Shell at 3 Months, 6 Months and 1 Year:
- For the Posterior Approach, the mean was 0.044 mm (Standard Deviation 0.11 mm).
- For the Lateral Approach, the mean was -0.065 mm (Standard Deviation 0.103 mm).
- For the Anterior Approach, the mean was -0.062 mm (Standard Deviation 0.272 mm).
- For the Overall Population, the mean was -0.025 mm (Standard Deviation 0.187 mm).
- Another measurement for the Posterior Approach showed a mean of 0.13 mm (Standard Deviation 0.314 mm).
What this means
The posted results detail the Pinnacle Acetabular Shell's migration over various time points up to two years post-implantation in osteoarthritis patients. The reported mean subsidence values, generally in the hundredths of a millimeter, suggest relative implant stability. Variations were observed across different surgical approaches. This data informs orthopedic surgeons in selecting devices and techniques for total hip arthroplasty, aiming to improve long-term patient outcomes. No comparative analyses or statistical significance values were reported.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT04070989, titled "Pinnacle RSA Study", were posted on 2025-10-21 on clinicaltrials.gov.