Year of Award

2015

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Interdisciplinary Studies

Department or School/College

Interdisciplinary Studies Program

Committee Chair

Ryan L. Mizner

Commitee Members

Kari J. Harris, Bret W. Tobalske, Charles L. Dumke, Jonathan M. Graham, Paul C. LaStayo

Publisher

University of Montana

Abstract

Despite consistent resolution of knee laxity and return to physical activity following ACL reconstruction, a growing body of evidence implicates impaired weight acceptance strategies as frequent primary drivers in a host of poor long-term outcomes. Most egregiously, the majority of the people with ACL reconstruction will show radiographic evidence of knee osteoarthritis within 15 years of surgery. Abnormal compression of the knee joint due to impaired knee flexion during weight acceptance is exacerbated by a tendency toward concomitant co-contraction of the knee musculature. Despite a plethora of proposed training paradigms, performance deficits after ACL reconstruction prove particularly resistant to enduring change. The studies included in this dissertation examine the mechanical and neuromuscular impairments in weight acceptance during landing from a jump that underlie the limitations to success following ACL reconstruction. A path toward improving functional recovery by treating impairments in landing is suggested and a novel training approach is tested. First, a cross-sectional study examines both the impaired patterns of neuromuscular recruitment in people who have returned to sporting activity following ACL reconstruction and their relationship to mechanics in landing. A pre-test/post-test laboratory study further examines the relationship between imposed changes in landing mechanics and co-contraction between the hamstrings and the quadriceps musculature. Clarification of neuromuscular activation and coordination impairments allows development of specific treatment techniques. To address limitations in current practice, a new device, the Bodyweight Reduction Instrument to Deliver Graded Exercise (BRIDGE), is validated in a third study, in which the effects of body weight support on the mechanics of repetitive single leg hopping are tested. The use of the BRIDGE is then described in a clinical case study. Finally, a randomized clinical trial determines whether high volume jump training with reduced loading intensity via body weight support will preferentially enhance motor learning for improved coordination of the neuromuscular system during high demand tasks such as single leg landing. This dissertation thereby advances the science of rehabilitation to more effectively target mechanical and neuromuscular impairments that devastatingly contribute to the risk of re-injury and early onset osteoarthritis following ACL reconstruction.

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© Copyright 2015 Audrey Rose Campbell Elias