Session: 06-09-01: Musculoskeletal and Sports Biomechanics

Paper Number: 147370

147370 - An Experimental Study of Weight-Based Compensation for Asymmetric Upper Limb Growth Secondary to Pre-Pubertal Operative Humeral Epiphyseal Plate Damage 

This research was conducted to verify previously-developed equations analyzing musculoskeletal strain caused by uneven weight distribution inherent in a case of upper limb length discrepancy. The issue is an imbalance due to the growth of a shorter humerus in the individual’s right upper limb (RUL) as the result of a prior surgery affecting the individual’s right humeral growth plate. This shortened RUL weighs less than the left upper limb (LUL), lowering the balancing moment on the torso. When the individual sprints during physical exercise, there is an imbalance in rotational momentum created between the two arms in the sagittal plane. This imbalance in momentum requires that the opposing lower limb of the shorter RUL, the individual’s left lower limb, had to drive harder, adding additional load on the hip flexor. To solve this biomechanical problem, kinematic equations were developed to model the motion of a sprinter. In particular, the model defines the influence of the opposing upper limb motion on the lower limb motion that results in forward motion while sprinting. Furthermore, the equations incorporate the rotational motions of the upper and lower limbs. Trials were conducted with a test subject having a shorter RUL than LUL. In the trials, the subject initially started from rest before accelerating to a constant speed. Two Kistler force plates were used to generate force vectors of each of the subject’s feet once the constant speed was reached. Kistler force plates contain piezoelectric sensors which can be used to record ground force reaction. In this case, the Kistler force plates measured the horizontal, transverse, and longitudinal force vectors created when the subject’s foot made contact with the plate. Additionally, the subject had several reflectors placed along his body. Using the Vicon three-dimensional (3D) optical motion analysis system, ten cameras in the laboratory captured the movement of the reflectors, generating vector motion for each limb during each trial run.To balance the rotational momentum of the upper limbs, a counteracting weight was attached to the wrist of the RUL in an attempt to minimize the effects on lower limb musculature. The difference in weight between each arm was determined, allowing a wearable device to be created which accounted for the difference. The device was attached to the subject’s right wrist to balance the weight of both arms. Hence, the left lower limb would not have to overcompensate for the shorter RUL’s lack of momentum. Similar running trials were conducted with the counterweight adjustment. The data from the trials, both with and without the counterweight, were compared to the theoretical equations determined from previous research.

Presenting Author: Vernon Fernandez Lawrence Technological University

Presenting Author Biography: Dr. Vernon Fernandez holds a PhD in systems engineering from Oakland University. He has been a professor in the Mechanical Engineering Department at Lawrence Technological University for the past 36 years. He has published several technical papers and holds several patents. He worked at the Chrysler Technical Center for 13 years as a part-time employee. His current research involves bio-inspired robotics, lightweight structures, and biomechanics.

Authors:

Dane Fernandez Lawrence Technological University
Ryan Fernandez Lawrence Technological University
Badih Jawad Lawrence Technological University
Vernon Fernandez Lawrence Technological University