Patients with combat-related lower limb amputations frequently experience chronic low back pain during long-term rehabilitation and prosthetic use. Altered biomechanics, asymmetric loading, gait disturbances, and changes in spinal alignment after limb loss may contribute to the development of persistent back pain. The severity and characteristics of low back pain may vary according to the level of amputation.

The LEVEL-BACK Study is a prospective observational study designed to evaluate the relationship between amputation level and chronic low back pain after combat-related amputation.

Participants with different levels of lower limb amputation will undergo clinical assessment of low back pain intensity, functional limitations, prosthesis use, and rehabilitation outcomes during follow-up.

The goal of the study is to improve understanding of how amputation level influences chronic low back pain after combat-related limb loss and to identify patients at increased risk for persistent spinal pain during rehabilitation.

Chronic low back pain is a common long-term complication following lower limb amputation and may significantly impair mobility, rehabilitation, prosthesis tolerance, and quality of life. Patients with combat-related amputations are particularly vulnerable because of severe tissue trauma, altered gait mechanics, asymmetric loading, repeated surgical interventions, and prolonged rehabilitation.

Biomechanical alterations after amputation may lead to abnormal spinal loading, pelvic asymmetry, trunk compensation, and increased energy expenditure during ambulation. These changes may contribute to chronic mechanical stress on the lumbar spine and development of persistent low back pain. The level of amputation may play an important role in this process, as more proximal amputations are frequently associated with greater gait disturbance, increased compensatory trunk movements, and higher biomechanical demand during prosthetic walking.

Despite increasing recognition of chronic low back pain after amputation, limited prospective data are available regarding the relationship between amputation level and spinal pain severity in combat-related trauma populations.

The LEVEL-BACK Study is a prospective observational study designed to evaluate the association between lower limb amputation level and chronic low back pain after combat-related amputation.

Participants with transtibial, transfemoral, and bilateral lower limb amputations will undergo longitudinal clinical assessment during rehabilitation follow-up. Study evaluations will include assessment of low back pain intensity, duration of symptoms, prosthesis use, functional mobility, rehabilitation outcomes, and pain-related disability.

The study aims to improve understanding of spinal pain mechanisms after combat-related limb loss and identify patient groups at increased risk for chronic low back pain according to amputation level.

Inclusion Criteria:

• Age ≥18 years
• Combat-related lower limb amputation
• Transtibial, transfemoral, or bilateral lower limb amputation
• Time since amputation ≥3 months
• Current or planned prosthesis use
• Ability to participate in rehabilitation assessment
• Ability to report low back pain intensity
• Ability to provide written informed consent

Exclusion Criteria:

• Traumatic spinal injury related to the initial combat trauma
• Previous spinal surgery before amputation
• Known severe spinal deformity
• Active spinal infection or malignancy
• Severe neurological disorder affecting mobility
• Non-combat-related amputation
• Inability to complete follow-up assessments
• Refusal or inability to provide informed consent

Participants will include adult patients with combat-related lower limb amputations undergoing rehabilitation and prosthetic recovery. The study population will consist of individuals with unilateral transtibial amputation, unilateral transfemoral amputation, or bilateral lower limb amputation. Participants will be recruited from military rehabilitation and trauma centers specializing in post-amputation care. The study aims to evaluate the relationship between amputation level and chronic low back pain during long-term rehabilitation and prosthesis use.

De-identified individual participant data including demographic characteristics, amputation level, low back pain intensity scores, functional mobility assessments, prosthesis use data, rehabilitation outcomes, analgesic consumption, and follow-up clinical evaluations collected during the study will be available for sharing. The study protocol, statistical analysis plan, and analytic code may also be shared upon reasonable request.