Michael Llewellyn PhD, Presenter: Nothing to Disclose

Melinda Cromie, Abstract Co-Author: Nothing to Disclose

Scott L. Delp PhD, Abstract Co-Author: Nothing to Disclose

Garry Evan Gold MD, MSEE, Abstract Co-Author: Consultant, Zimmer Holdings, Inc Consultant, ICON plc Research support, General Electric Company

Our in vivo measurements using ultrasound and sarcomere imaging compare favorably to cadaver data. When ultrasound imaging is combined with optical sarcomere imaging, musculoskeletal characterization of fiber geometry can quickly generate highly accurate subject-specific models for pre-operative planning.

Ultrasound is used in conjunction with a minimally invasive sarcomere imaging to provide the most accurate characterization of biomechanical parameters of muscle fibers in individual subjects, which are then compared to existing data from cadavers and open surgeries.

Imaging was performed on the extensor carpi radialis (ECRB) of healthy volunteers (n=10) at wrist angles of 30, 0, and -30 degrees of flexion. Ultrasound images were taken on a Sonosite 180Plus with an L38/10-5 MHz linear transducer at a depth of <3cm. Sarcomere images were taken on a custom-built microendoscopy system using 500µm endoscopes inserted transcutaneously through 20ga needle tubes. All ultrasound images were analyzed for fiber length, pennation angle and an estimate of muscle cross-sectional area. All sarcomere images were post were analyzed for average sarcomere length.

Average fiber length of the subjects ranged from 6.02±0.09 cm (n=10, avg±s.e.) at 30° flexion to 3.70±0.04cm at 30° extension. At neutral joint position, the fiber length by ultrasound was 4.87±0.04cm, which is not significantly different from cadaver data 4.77 ±0.37cm (p=0.31). Average pennation angle by ultrasound of ECRB was 7.7±0.19°, which is not significantly different from cadaver data at 8.9±0.89° (p=0.26). Average PCSA by ultrasound was 265±2.7mm2, which was again not significantly different from cadaver data at 273±8.0 mm2 (p=0.37). Average sacomere length measurements by minimally invasive microendoscopy ranged from 2.96±0.01µm at 30° extension to 3.34±0.02 µm at 30° flexion, which are significantly different in extension from intraop measurements (2.65±0.07 µm, p=0.001), but not in flexion (3.38±0.07, µm p=0.75).

Llewellyn, M, Cromie, M, Delp, S, Gold, G, In Vivo Ultrasound and Microendoscopic Sarcomere Imaging for Accurate Muscle Geometry.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9007296.html