Biscapular Protraction Force and Excursion in Adult Patients With Traumatic Brachial Plexus Injuries: A Comparative Study.

Purpose: Traditional body-powered upper limb prostheses use a Bowden cable to translate shoulder and residual upper limb movements into forces that control the terminal device. The necessary force and excursion required to use a traditional body-powered prosthesis in patients with traumatic brachial plexus injuries (BPI) has yet to be ascertained. This study compared the force and excursion generated during biscapular protraction in adults with traumatic BPI compared to healthy volunteers.

Methods: Thirty nonamputee volunteers, divided into BPI and uninjured control groups and matched for age and sex, were recruited, consented, and comprised the study's cohort. Biscapular protraction force and excursion were measured using a figure-of-8 harness simulating body-powered prosthesis control. Age, sex, anatomical dimensions, and cohorts were compared to determine their potential effects on force and excursion.

Results: The control group demonstrated significantly higher force (4.2 vs 1.0 kg) and excursion (52.6 vs 16.7 mm) than the BPI group. After adjusting for age, sex, and anatomical dimensions, the differences remained.

Conclusions: Complete BPI patients demonstrated considerably diminished biscapular force and excursion compared to healthy volunteers. These differences illustrate the potential challenges in use of body-powered prostheses in patients with BPI. Patients with BPI may require alternative strategies to exploit contralateral scapular motion to enable use of terminal devices.

Clinical relevance: Patients with complete BPI exhibit considerably reduced biscapular force and excursion compared to healthy individuals, limiting their potential to operate body-powered prostheses.