Trial results comparing functionally aligned (FA TKA) and mechanical axis aligned (MA TKA) total knee arthroplasty for osteoarthritis were posted on ClinicalTrials.gov on 2025-08-08, involving 100 participants.
Background
Osteoarthritis is a degenerative joint disease commonly affecting the knee, leading to pain, stiffness, and reduced mobility. Total knee arthroplasty (TKA) is a standard surgical intervention for severe osteoarthritis. This study aimed to compare two different alignment techniques in robotic-arm assisted TKA—mechanical alignment (MA TKA) and functional alignment (FA TKA)—to determine if one approach offers superior patient recovery and clinical outcomes. The objective was to assess clinical and radiological outcomes between these two methods.
Trial design
This completed study, designated as Phase NA, enrolled 100 participants with conditions including Osteoarthritis and Osteo Arthritis Knee. The objective was to compare clinical and radiological outcomes in robotic-arm assisted TKA using mechanical alignment versus robotic-arm assisted TKA with functional alignment. These outcomes were used to determine if patient recovery is better with functionally aligned Mako robotic-assisted total knee arthroplasty or mechanically aligned Mako robotic-assisted total knee arthroplasty.
Key results
The trial reported several key measurements after 2 years from baseline for both alignment techniques:
- Change in Forgotten Joint Score After 2 Years From Baseline (score on a scale):
- Functionally Aligned Total Knee Arthroplasty: A mean score of 50.1 (Standard Deviation 28.3).
- Mechanical Axis Aligned Total Knee Arthroplasty: A mean score of 46.4 (Standard Deviation 32.4).
- Change in Oxford Knee Score After 2 Years From Baseline (score on a scale):
- Functionally Aligned Total Knee Arthroplasty: A mean score of 17.0 (Standard Deviation 7.5).
- Mechanical Axis Aligned Total Knee Arthroplasty: A mean score of 17.2 (Standard Deviation 8.6).
- Change in Range of Motion After 2 Years From Baseline (deg):
- Functionally Aligned Total Knee Arthroplasty: A mean of 2.8 (Standard Deviation 9.9).
- Mechanical Axis Aligned Total Knee Arthroplasty: A mean of 2.8 (Standard Deviation 9.3).
What this means
The posted results suggest that both functionally aligned and mechanical axis aligned robotic-arm assisted total knee arthroplasty approaches yield comparable clinical outcomes at 2 years post-surgery for patients with osteoarthritis. While the functionally aligned group showed a slightly higher mean Forgotten Joint Score, the Oxford Knee Score and Range of Motion were very similar between the two groups. These findings contribute to the understanding of different TKA alignment strategies, indicating that both methods may offer similar patient recovery profiles based on these specific outcome measures.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT04748510, titled "Functionally Aligned vs Mechanical Axis Aligned Total Knee Arthroplasty", were posted on 2025-08-08 on clinicaltrials.gov.