A transformation method to estimate muscle attachments based on three bony landmarks

Area of Science:

• Biomechanics
• Musculoskeletal modeling
• Human anatomy

Background:

• Accurate musculoskeletal models require precise muscle attachment locations for subject-specific scaling.
• Existing methods may lack accuracy or scalability for diverse populations.

Purpose of the Study:

• To develop and validate a novel scaling method for estimating muscle attachment sites on homologous skeletal segments.
• To assess the accuracy of this method using cadaveric data and evaluate its impact on biomechanical models.

Main Methods:

• A scaling technique was developed using three bony landmarks per segment to estimate muscle attachment locations.
• A dataset of 17 shoulder muscles from seven cadavers was utilized to evaluate the method's precision.
• Root Mean Square Error (RMSE) was calculated to quantify estimation accuracy.

Main Results:

• The scaling method demonstrated satisfactory accuracy, with mean RMSEs of 7.6mm for scapular muscles and 11.1mm for humeral muscles.
• Analysis using an upper extremity model indicated acceptable influence of RMSE on glenohumeral elevation muscle moment arms.

Conclusions:

• The proposed scaling method provides a reliable approach for estimating muscle attachment locations in musculoskeletal modeling.
• Further research should investigate inter- and intra-subject variability and model sensitivity to error variations.