In Taiwan, there are more than 23,000 individuals with spinal cord injuries (SCI, mean age: 27 years), with an increment of new 1,200 SCI individuals each year. Recovery of ambulatory function is among the most important therapeutic goals because 92% of the individuals with SCI have to use the wheelchair for the rest of their lives.

The lower limb powered exoskeleton robot, FREE Walk, used for training in this research was developed by FREE Bionics Inc. The main purpose of this research is to test the safety and feasibility of FREE Walk exoskeleton robot. In addition, the research will further investigate the range of injury levels for the intended SCI users and the learning time needed for the users to independently operate the exoskeleton robot.

Individuals with SCI who meet the inclusion criteria will be referred to the investigators. Participants will be given consent forms and explained the research before participating. The participants must pass the initial evaluation described below in order to go through robot training: (1) medical history, (2) bone density, (3) joint range of motion, ROM (4) strength (manual muscle test, MMT), (5) muscle tone (modified Ashworth scale, MAS).

The training program consists of 5-min preparation, 50-min of functional activities training including weight shifting, sit-down, stand-up, stepping and walking, and 5-min training feedback. Every participant will receive at least 20 training sessions (1 hour per session, 2-5 sessions per week) and an post-training evaluation after completion of training. The post-training evaluation includes the following tests: timed up-and-go test, 10-meter walk test, and 6-minute walk test.

Inclusion Criteria:

1. Spinal cord injury patients whose injury levels range from C7 to L5, ASIA impairment scale A to D, can use forearm crutch and can't walk without an assistive device.
2. In a stable condition, for example, at least 3 months after first injury/onset, or with stable spine, or had been corrected (internal fixation).
3. Age between 18-70.
4. height between 150-190cm; weight less than 100kg; thigh length between 32-47cm; leg length (from lateral epicondyle of femur to sole) between 23-59cm.
5. Normal joint range of motion(ROM) of both lower extremities and upper extremities or ROM limitation will not affect ambulation.
6. Can maintain trunk stability with or without hand support in sitting position for 60s.

Exclusion Criteria:

1. Combine other neurological diseases, for example, stroke, cerebral palsy, Parkinson's disease,... etc.
2. Femoral T-score <-2.5. (Doctor's approval must be obtained for those who with femoral t-score between -2.5 and -3).
3. Other medical conditions which will affect weight bearing or ambulation.
4. Medical history including fracture(due to osteoporosis in the past 2 years), heart failure, myocardial infarction.
5. Skin conditions including allergy, pressure sore, infection, ...etc.
6. Impaired mental or cognitive conditions that will affect training or evaluation.
7. Severe contracture or limited joint range of motion of lower extremities.
8. Severe spasticity which will impede the movement of exoskeleton robot.
9. Heterotopic ossification.
10. non-union fracture or open wound.
11. pregnancy.
12. other conditions that is not applicable for use the exoskeleton robot.