Mechanical loading of bone-anchored implants during functional performance tests in service members with transfemoral limb loss.
Jonathan R Gladish, Christopher L Dearth, Mark D Beachler and 3 others
PMID 38560026WHAT IT FOUND
In four active service members with bone-anchored leg prostheses, sharp turns and side-steps generated peak implant loads up to 181% higher than straight walking.
These transient spikes approach the device's fail-safe release thresholds, highlighting the need for personalized component design.
Key findings
01Peak forces during functional tests were up to 181% larger than during straight-line walking, with medial-lateral forces peaking during side-stepping and anterior-posterior forces during agility tests.
02Peak internal/external rotation moments were up to 211% larger than during straight-line walking, occurring during turning and weaving tasks.
03Several measured peak moments exceeded the fail-safe release thresholds for bending and axial twist, though no actual release occurred during testing.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study included only four participants, all high-functioning service members, so the findings cannot be generalized to the broader population with limb loss. The sensor could only be fitted to the right side in participants with bilateral amputation due to space constraints, leaving left-side loading unmeasured. The sample size was too small to determine if the observed loads are typical or if they vary significantly between individuals. The study did not measure long-term effects of these loads on bone health or implant survival, only peak values during short tests.
Declared interests
Funding was provided by the Congressionally Directed Medical Research Program. The authors declared financial support for the research and publication.
The easy way to misread this
Do not assume these load levels apply to all patients with osseointegrated prostheses. The participants were young, active service members with high-functioning mobility, and the sample size of four cannot represent the variability in the wider clinical population.