Development and testing of the aerial porter exoskeleton.

Back pain is one of the largest drivers of workplace injury and lost productivity in industries around the world. Back injuries were one of the leading reasons in resulting in days away from work at 38.5% across all occupations, increasing for manual laborers to 43%. While the cause of the back pain can vary across occupations, for materiel movers it is often caused from repetitive poor lifting. To reduce the issues, the Aerial Porter Exoskeleton (APEx) was created. The APEx uses a hip-mounted, powered exoskeleton attached to an adjustable vest. An onboard computer calculates the configuration of the user to determine when to activate. Lift form is assisted by using a novel lumbar brace mounted on the sides of the hips. Properly worn, the APEx holds the user upright while providing additional hip torque through a lift. This was tested by having participants complete a lifting test with the exoskeleton worn in the "on" configuration compared with the exoskeleton not worn. The APEx has been shown to deliver 30 Nm of torque in lab testing. The activity recognition algorithm has also been shown to be accurate in 95% of tested conditions. When worn by subjects, testing has shown average peak reductions of 14.9% BPM, 8% in VO2 consumption, and an 8% change in perceived effort favoring the APEx.

An efficient robotic tendon for gait assistance.

A robotic tendon is a spring based, linear actuator in which the stiffness of the spring is crucial for its successful use in a lightweight, energy efficient, powered ankle orthosis. Like its human analog, the robotic tendon uses its inherent elastic nature to reduce both peak power and energy requirements for its motor. In the ideal example, peak power required of the motor for ankle gait is reduced from 250 W to just 77 W. In addition, ideal energy requirements are reduced from nearly 36 J to just 21 J. Using this approach, an initial prototype has provided 100% of the power and energy necessary for ankle gait in a compact 0.95 kg package, seven times less than an equivalent motor/gearbox system.

Spring over muscle (SOM) actuator for rehabilitation devices.

For people affected by stroke, frequent physical therapy has been shown to be an effective form of rehabilitation. To this goal, several home therapy devices have been developed. Many of these devices may benefit from the use of a bidirectional pneumatic muscle actuator. This work presents the concept and design of the double-acting, compliant, spring over muscle (SOM) actuator. The principle design uses a spring in parallel with a pneumatic muscle actuator. This concept is economical, and easily scalable. Additionally, a design proposal for an ankle rehabilitation device, which incorporates the SOM actuator, is discussed.

Methods to locate center of gravity in scoliosis.

STUDY DESIGN: Prospective evaluation of the location of the center of gravity during supine, standing, and gait. OBJECTIVE: Develop methods to quantify center of gravity locations in patients with scoliosis and controls and to evaluate the merit of the quantitative assumptions relative to spinal fusion surgery. SUMMARY AND BACKGROUND DATA: The center of gravity, or balance point of the body, is generally considered to be the single best estimate of the body's location. To date, investigators have not examined the body's center of gravity location to assist surgical planning to maintain and/or restore coronal and sagittal plane balance, nor have they used center of gravity location to help assess surgical outcomes. MATERIALS AND METHODS: The whole-body center of gravity (MR-COG) was determined for three subjects from magnetic resonance imaging data obtained supine. The whole-body center of gravity was also determined using subject specific (SS-COG) and literature-based (STD-COG) segment center of gravity locations in conjunction with a video motion capture system obtained supine, standing and during gait. RESULTS: Differences existed among the three methods of determining COG locations in supine, with the SS-COG and MR-COG being most closely aligned. Results from gait data indicated typical anterior/superior and right/left COG shifts during the gait cycle. The SS-COG method consistently determined a COG location inferior to the STD-COG method; however, variation within the gait cycle was similar. Shifts in COG locations relative to a coordinate system fixed in the pelvis were more than 5 cm in the superior/inferior direction, approximately 4 cm in the anterior/posterior direction, and minimal in the left/right direction. CONCLUSIONS: Methods have been developed to determine locations of the whole body COG in both preoperative and postoperative subjects undergoing spinal fusion surgery and controls. The methods are robust to include men and women, subjects with and without instrumentation, and subjects in various positions including gait.

Prospective evaluation of trunk range of motion in adolescents with idiopathic scoliosis undergoing spinal fusion surgery.

STUDY DESIGN: Prospective evaluation of spinal range of motion in patients with adolescent idiopathic scoliosis undergoing a spinal fusion. OBJECTIVE: Evaluate changes in triplanar spine range of motion following spinal fusion. SUMMARY AND BACKGROUND DATA: Preoperative and postoperative radiographs have been the major form of outcome analysis of adolescent idiopathic scoliosis fusions. Although the radiographs document static positions of the skeletal system, they do not document dynamic changes. METHODS: Thirty patients with adolescent idiopathic scoliosis undergoing an instrumented spinal fusion underwent triplanar range of motion tests before surgery and at 12 and 24 months after surgery. Videography with reflective surface markers was used to capture the motions. A fused region, unfused regions above and below the fusion, and a global spinal measure were used to assess changes. RESULTS: Results indicated a loss of motion in the coronal and sagittal planes for the fused and unfused spinal regions and a loss of motion in the coronal, sagittal, and transverse planes for the global measurements. Results also indicated preoperative and continued postoperative right and left lateral flexion asymmetries. No significant correlations were found between the total fused levels and changes in range of motion. No significant correlations were found between the lowest instrumented vertebra and changes in range of motion. CONCLUSIONS: Whereas range of motion was reduced in the fused regions of the spine, it was also reduced in unfused regions. The lack of compensatory increase in motion at unfused regions contradicts current theory and suggests early postoperative range of motion therapy to facilitate motion in unfused regions.