John Willson
Advisor: Davis
McK 337
BIOMS Dissertation Defense: Hip strength and lower extremity mechanics in females with and
without patellofemoral pain
Abstract
Background: Patellofemoral pain syndrome (PFPS) remains a prevalent athletic injury,
especially among females. Hip strength differences between females with and without PFPS has
led to speculation that individuals with PFPS are prone to abnormal lower extremity alignment
during weightbearing activities due to an inability to adequately resist external moments at the
hip. This tendency for abnormal alignment may be especially evident if weightbearing activities
are performed in a state of fatigue. Purpose: The purpose of this study is to analyze hip strength
and lower extremity mechanics of females with and without PFPS during weightbearing
activities associated with progressively increasing loads. Additionally, we will analyze the effect
of fatigue on these lower extremity mechanics. Finally, we intend to further study the validity of
a measure of lower extremity alignment that is appropriate for a clinical setting.
Methods: Twenty active females with PFPS and 20 active females with no lower extremity
injuries will be recruited for this study. Isometric lateral trunk flexion, hip abduction, hip
external rotation, knee extension, and knee flexion peak isometric strength will be collected for
each subject. Lower extremity mechanics will then be collected as subjects perform activities
with progressively greater loads (single leg squat, running, single leg jumping). Subjects will
then participate in a functional lower extremity exertion protocol. At the conclusion of the
protocol, lower extremity mechanics during single leg jumps will be recorded to compare to the
initial set of jumps. Prior to the exertion protocol, digital images of the frontal plane projection
angle of the knee during single leg squats will be collected to compare with 3D lower extremity
mechanics during these three activities. Significance: It is hoped that information gained from
this research will lend insight into factors that contribute to the etiology and exacerbation of
PFPS, as well as provide a basis for more effective treatment interventions.