Reconstruction of the lower limb bones from digitised anatomical landmarks using statistical shape modelling.
Daniel Nolte, Siu-Teing Ko, Anthony M J Bull and 1 others
PMID 32092603WHAT IT FOUND
Shape models did not clearly beat simple scaling for adult lower limb bone reconstruction.
Surface errors were on average smaller, but hip centre estimates were not clearly better.
Key findings
01Shape model reconstructions from skin landmarks with soft tissue correction did not differ significantly from reconstructions using landmarks segmented on the bone surface.
02Linear scaling errors were larger than shape model errors on average, but the difference reached significance only when compared with reconstructions from segmented bony landmarks.
03Soft tissue artefact regressions were significant only for the greater trochanter, lateral epicondyle and medial epicondyle; other landmarks did not show significant regression relationships.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was done in healthy participants, not in patients with gait or musculoskeletal problems. Soft tissue offsets were measured lying down in MRI but used for upright motion lab digitisation, and compression by the rater could have affected landmarks. The shape model was built from 35 participants, which the authors called limited. Only 17 of the scanned participants had motion lab digitisation. Cartilage thickness variation in joint centre estimation was not addressed. Hip centre comparisons used the greater trochanter to build a local coordinate frame, and that landmark had the largest soft tissue artefact. The method was not tested in children, and the authors say child-specific models would be needed. No clinical outcome or treatment effect was measured.
Declared interests
The authors declared no financial or personal relationships that could inappropriately influence their work.
The easy way to misread this
Do not read this as evidence that changing gait models will improve patient care. The study tested bone shape reconstruction accuracy in 35 healthy participants and did not assess clinical outcomes or treatment effects.