Exercise Intervention for Unilateral Amputees With Low Back Pain

Amputation to the lower extremity is a life-changing event. Approximately 2 million Americans
live with limb loss, with ~45% of losses occurring from traumatic mechanisms. After the
injury has healed and a prosthetic limb is fitted, the long-term care for amputees typically
focuses on maintenance of the prosthesis fit and optimizing physical function. Even with
high-quality prostheses, amputation permanently impacts biomechanical symmetry of gait. After
unilateral transtibial or transfemoral amputation, skeletal muscle atrophy occurs in the
lower extremity and back. Asymmetric gait causes mechanical stresses at lumbar spine, and
loss of muscle mass and strength, all of which exaggerate gait aberrations. As a result,
chronic low back pain (LBP) can develop. LBP is a common, but often unaddressed, secondary
complication in over half of the unilateral amputee population.

Lower extremity amputees face numerous physical and emotional challenges after their
injuries. Performing ambulatory activities are more physically demanding with an amputation
than without. The psychological stress levels are often high after an amputation,
contributing to activity avoidance and limiting participation in load-bearing activities. LBP
independently contributes to costly health burdens such as addiction to pain medicine,
depression and lifestyle diseases and LBP erodes physical and mental quality of life (QOL).
Pain is also related to skeletal muscle atrophy in the low back. The combination of an
amputation injury and LBP may amplify ambulation-related limitations and further deteriorate
QOL. Unilateral lower extremity amputees who suffer from chronic LBP therefore may therefore
experience greater walking limitations, physical activity avoidance and physiological changes
to skeletal muscle, strength and perceived QOL than people with back pain or amputation
alone.

Long-term care for amputees requires a team of physicians, prostheticians, therapists and
other specialists. Patients often travel long distances to receive their care. Patients with
limited resources may not be able to maintain a long-term relationship with therapists due to
cost restrictions. Home-based interventions that target LBP could substantially impact the
secondary disease burden and help restore QOL in the amputee population. In the general
population, evidence indicates that consistently-performed muscle strengthening activity is
associated with significantly lower odds of developing back pain in men and women. Resistance
exercise is effective for lumbar muscle strength gains, functional gains in ambulation and
movement and for improving both physical and mental aspects of QOL. Resistance training
benefits in strength, motor skills, and many aspects of quality of life (both functional and
psychosocial) are seen throughout several different demographics; from young adults to the
elderly.

Current clinical paradigms to treat general LBP include referral to physical therapy for
strengthening exercise programs. For amputees, challenges to receiving therapeutic care
include travel distance, and financial limitations for exercise facility memberships or
therapy copayments. Patients may not be able to sustain and therapy gains over the long-term
when therapy benefits run out. Thus, exercise to treat LBP in amputees must be accessible,
low or no cost and sustainable. A significant deficit in the clinical literature is that the
study team does not know the effectiveness of home-based resistance training on different
chronic musculoskeletal pains in amputees. Moreover, the mechanisms that may contribute to
effectiveness of strength training on pain relief in amputees are not clear. The problem is
therefore multifaceted: 1) amputees experience permanent anatomic changes that impact
load-bearing activity, back pain and QOL; 2) chronic LBP treatment is not often a focus for
the long-term management of the unilateral lower extremity amputee; 3) chronic LBP can
develop in amputees as a consequence of asymmetric movement patterns, lumbar muscle atrophy
and low muscle strength, but the relative contribution of each to pain severity is not known.
These evidence gaps are significant barriers to the optimization of care for this special
population by clinical teams who care for these individuals, and for determination of pain
responders with strengthening exercise.

Inclusion Criteria:

- Between 18-60 years of age

- English speaking

- Suffering from chronic LBP (>3 months with ≥3 pain episodes per week)

- Baseline pain of ≥3 points out of 10 on the NRSPain scale

- Amputation ≥1 year prior and their current prosthesis must have been worn for at least
6 months (prosthesis K-Level of K2 or greater, indicating the subject is able to
ambulate and traverse low-level environmental barriers such as curbs, stairs, or
uneven surfaces).

- Must have regular access to a computer for skype, or a mobile phone or iPAD to perform
facetime

Exclusion Criteria:

- Acute back injury

- Any other chronic back pathology (i.e. herniated disc, ankylosing spondylosis, other
related neurologic disease)

- Pain symptoms or functional limitations (including those that may require assistive
devices) that preclude participation in resistance exercise or physical activity

- Back surgery within the past two years that restrict daily physical activities

- Currently enrolled in any other resistance or strengthening exercise interventions

- Pregnant