Exercise intervention for unilateral amputees with low back pain: study protocol for a randomised, controlled trial

Wasser et al. Trials (2017) 18:630 DOI 10.1186/s13063-017-2362-0 STUDY PROTOCOL Open Access Exercise intervention for unilateral amputees with low back pain: study protocol for a randomised, controlled trial Joseph G. Wasser1*, Daniel C. Herman1, MaryBeth Horodyski1, Jason L. Zaremski1, Brady Tripp2, Phillip Page3, Kevin R. Vincent1 and Heather K. Vincent1 Abstract Background: Atraumatic lower limb amputation is a life-changing event for approximately 185,000 persons in the United States each year. A unilateral amputation is associated with rapid changes to the musculoskeletal system including leg and back muscle atrophy, strength loss, gait asymmetries, differential mechanical joint loading and leg length discrepancies. Even with high-quality medical care and prostheses, amputees still develop secondary musculoskeletal conditions such as chronic low back pain (LBP). Resistance training interventions that focus on core stabilization, lumbar strength and dynamic stability during loading have strong potential to reduce LBP and address amputation-related changes to the musculoskeletal system. Home-based resistance exercise programs may be attractive to patients to minimize travel and financial burdens. Methods/design: This study will be a single-assessor-blinded, pre-post-test randomised controlled trial involving 40 men and women aged 18–60 years with traumatic, unilateral transtibial amputation. Participants will be randomised to a home-based, resistance exercise group (HBRX) or a wait-list control group (CON). The HBRX will consist of 12 weeks of elastic resistance band and bodyweight training to improve core and lumbopelvic strength. Participants will be monitored via Skype or Facetime on a weekly basis. The primary outcome will be pain severity (11-point Numerical Pain Rating Scale; NRSpain). Secondary outcomes will include pain impact on quality of life (Medical Outcomes Short Form 36, Oswestry Disability Index and Roland Morris Disability Questionnaire), kinematics and kinetics of walking gait on an instrumented treadmill, muscle morphology (muscle thickness of multifidus, transversus abdominis, internal oblique), maximal muscle strength of key lumbar and core muscles, and daily step count. Discussion: The study findings will determine whether a HBRX program can decrease pain severity and positively impact several physiological and mechanical factors that contribute to back pain in unilateral transtibial amputees with chronic LBP. We will determine the relative contribution of the exercise-induced changes in these factors on pain responsiveness in this population. Trial registration: ClinicalTrials.gov, ID: NCT03300375. Registered on 2 October 2017. Keywords: Amputee, Gait, Low back pain, Physical function, Disability, Randomised controlled trial * Correspondence: 1 Department of Orthopaedics and Rehabilitation, UF Health Orthopaedics and Sports Medicine Institute (OSMI), University of Florida, Gainesville, FL 32611, USA Full list of author information is available at the end of the article © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Wasser et al. Trials (2017) 18:630 Background Amputation to the lower extremity is a life-changing event. Approximately two million Americans live with limb loss. An estimated 45% of these amputations are caused by traumatic mechanisms [1, 2]. Once the injury has healed and a prosthetic limb is fitted, the long-term care focuses on maintenance of the prosthesis fit and optimizing physical function [3]. However, even with the use of high-quality prostheses, biomechanical symmetry of gait remains permanently altered [4]. A unilateral transtibial amputation leads to progressive skeletal muscle atrophy in the affected lower extremity [5] and back [6]. The collective effects of asymmetric gait, loss of muscle mass, and reduction of strength increase mechanical stresses at the lumbar spine [4, 7]. These stresses contribute to low back pain (LBP) onset. LBP is a secondary complication in over half of the unilateral amputee population [8–10]. LBP interferes with physical and mental wellbeing and overall quality of life (QOL) [10]. Long-term care for amputees requires a team of physicians, prostheticians, therapists, and other specialists. Patients often travel long distances to receive their care, and many have resource limitations. Patients may not be able to maintain consistent long-term relationships with therapists or purchase fitness memberships due to financial constraints. Effective home-based interventions that target LBP could minimize travel or cost burden to the patient and substantially impact the secondary disease burden. An exercise mode with strong potential for a home-based intervention is resistance exercise. In the general population, resistance exercise is associated with lower odds of developing LBP [11]. Resistance exercise increases lumbar muscle strength, physical functional, and both physical and mental aspects of QOL [12–17]. The impact and effectiveness of resistance training on chronic LBP severity and pain impact in amputees is not yet known. Moreover, the mechanisms that may contribute to the effectiveness of strength training on LBP relief in amputees are not clear. These evidence gaps are significant barriers to the optimization of care for this special population. The aims of this study are to determine whether home-based resistance exercise (HBRX) among unilateral transtibial amputees with LBP can reduce LBP severity and its impact on QOL and improve the biomechanical symmetry of gait. The relative contribution of key factors that predict pain responsiveness with HBRX will be determined. The research hypotheses are as follows: (1) HBRX will reduce subjective pain ratings, pain medication use, and the impact of pain on QOL; (2) HBRX will reduce gait asymmetries and increase gait velocity; and (3) HBRX-induced changes in lumbar muscle strength, lumbar muscle cross-sectional area, and perceived QOL will predict pain responsiveness for LBP in unilateral transtibial amputees. Page 2 of 11 Methods Trial design This study will be a single-assessor-blinded, pre-post-test randomised controlled trial. The study will follow the principles of the Consolidated Standards of Reporting Trials for randomized, two-group, parallel studies [18, 19]. Figure 1 provides the study flow and Fig. 2 shows a version of the Standard Protocol Items: Recommendations for Inte (...truncated)