Author ORCID Identifier

https://orcid.org/0000-0002-8076-4160

Year of Publication

2019

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Health Sciences

Department

Rehabilitation Sciences

First Advisor

Dr. Joshua D. Winters

Second Advisor

Dr. Arthur J. Nitz

Abstract

Low back pain in collegiate athletes has been reported at a rate of 37% from a wide array of sports including soccer, volleyball, football, swimming, and baseball. Whereas, in a military population the prevalence of low back pain is 70% higher than the general population. Compensatory movement strategies are often used as an attempt to reduce pain. Though compensatory movement strategies may effectively reduce pain, they are often associated with altered lower extremity loading patterns. Those who suffer from chronic low back pain tend to walk and run slower and with less trunk and pelvis coordination and variability. Individuals with low back pain also tend to run with more stiffness in their knees. Moving with less joint coordination and more stiffness are potential compensatory movement patterns acting as a guarding mechanism for pain.

Overall the purpose of this project was to determine how chronic low back pain influences lower extremity biomechanics and shock attenuation in active individuals compared to healthy individuals and examine how the altered lower extremity biomechanics are related to clinical outcome measures. We hypothesized that individuals who present with chronic low back pain are more likely to exhibit higher vertical ground reaction forces and less knee flexion excursion during landing, compared to healthy individuals. We also hypothesized that individuals with chronic low back pain will have a reduced ability to attenuate shock during landing compared to the healthy individuals.

This study was a case control design in which physically active individuals suffering from chronic low back pain were matched to healthy controls. All participants reported for one testing session to assess self-perceived knee function in the form of the Knee Osteoarthritis Outcomes Score (KOOS), lower extremity strength and mechanics during three landing tasks. Isometric strength was assessed using an isokinetic dynamometer during hip abduction, hip extension, and knee extension. The landing tasks included a drop vertical jump, a single leg hop, and a crossover hop. A three-dimensional motion analysis system with two in-ground force plates and four inertial measurement units were used to assess lower extremity mechanics during the landing tasks.

Individuals with low back pain presented with reduced KOOS scores compared to healthy individuals in four of the five subscales, including Symptoms (p=0.007), Pain (p=0.002), Activities of Daily Living (p=0.021), and Quality of Life (p=0.003). Alternatively, while there were some strength, kinematic, and kinetic between limb asymmetries noted in the low back pain group, there were not between group differences with the healthy individuals. In the low back pain group, individuals presented with greater dominant limb knee extension strength (p=0.039) and greater dominant limb ankle plantarflexion at initial contact during the drop vertical jump, compared to the non-dominant limb (p=0.022). Individuals with low back pain also presented with greater non-dominant limb tibia impact during the single limb hop (p=0.008).

While we did not identify any mechanical differences between individuals suffering from chronic low back pain and those who do not, we did identify that an active population suffering from low back pain does present with decreased self-perceived knee function compared to active individuals without low back pain. As these groups biomechanically perform similarly, they do not clinically perform the same, specifically, in terms of the KOOS. Such differences should not be overlooked when treating active populations with low back pain. If this population is presenting with altered self-perceived knee function at a young age, it is likely that it will continue to decline and negatively affect their function.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.021

Funding Information

American Society of Biomechanics - Student Grant in Aid, 6/2018-6/2019

Rehabilitation Sciences Pilot Program, 4/2018-6/2019

Available for download on Thursday, January 07, 2021

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