Gait is an essential daily activity performed through the complex coordination of the central and peripheral nervous systems and the musculoskeletal system. Gait disorders can negatively affect quality of life, increase the risk of falls, decrease the ability to perform daily activities, and limit physical activity. Gait disorders can result from various musculoskeletal conditions, with hip osteoarthritis, avascular necrosis of the femoral head, and hip fractures being the most representative causes.

In the early stages of hip osteoarthritis, avascular necrosis of the femoral head, or non-severely displaced hip fractures, various intervention therapies, including rehabilitation exercise therapy and injection treatments, can be attempted. However, these intervention therapies only alleviate symptoms and cannot prevent disease progression. Consequently, most patients eventually experience thinning of the full-thickness hip cartilage, collapse of the femoral head, nonunion, or worsening displacement, which leads to restricted hip range of motion. As a result, lower limb muscle weakness and functional decline occur, ultimately requiring hip surgeries such as total hip arthroplasty or open reduction and internal fixation. Although most patients experience a recovery in gait ability after hip surgery, some show a slower recovery rate or fail to achieve normal walking.

It has been reported that over 80% of function is recovered by three months after surgery; however, during this period, patients experience limitations in performing daily activities. As a compensatory mechanism, excessive weight-bearing on the non-operated limb may occur, increasing the risk of overloading the non-operated hip. This may lead to the development of osteoarthritis in the non-operated limb and has also been reported to increase the risk of falls. Therefore, various methods are being studied to facilitate gait function recovery after hip surgery and promote an early return to daily activities.

Therefore, this study aims to explore the clinical feasibility of the Angel Suit H10 (Angelrobotics, Seoul, Korea) by assessing whether wearing the Electrically Powered Orthopedic Exercise Device improves gait function in patients who have undergone hip surgery, along with evaluating user satisfaction and device safety.

(1) Overview of study design This investigator-initiated exploratory study is a pilot study designed to evaluate the effectiveness and safety of the Electrically Powered Orthopedic Exercise Device by measuring and analyzing gait function and balance ability in patients who have undergone hip surgery under both non-wearing and wearing conditions.

(2) Experimental Group and Evaluation Procedures

1. Participant Selection:

   This study includes a single test group with a total of 30 participants. The selection of participants for the electrically powered orthopedic exercise device and the overall study process will be conducted under the prescription and guidance of a rehabilitation medicine specialist, and supervised by assistants (physicians and occupational therapists). The examiner will collect clinical information and conduct a screening assessment for each participant.

2. Evaluation Phase Without Device:

   After the screening test, participants undergo assessments of walking ability and balance without wearing the motorized orthopedic exercise device. A 10-minute rest period is provided between each assessment. If the participant wishes, additional rest time is allowed and recorded in the case report form. The assessments include the 10-Meter Walk Test, the 6-Minute Walk Test, the Timed Up and Go Test, and the Berg Balance Scale. These evaluations are conducted in the rehabilitation function testing room on the second floor of the facility under the supervision of the research team (physician and either a physical or occupational therapist).

3. Pre-Adaptation Phase:

   After the evaluations without the device, a total of four adaptation sessions are conducted, during which the participant wears the device and performs short-distance walking within 10 meters. These sessions are designed to help the participant become familiar with the operation and wearing method of the H10 device. Appropriate device settings are configured for each participant to minimize any potential inexperience or anxiety during use. Participants must complete all four adaptation sessions, and each session should be conducted within a two-week interval.

4. Evaluation Phase:

After completing all four adaptation sessions, participants undergo assessments of walking ability and balance while wearing the motorized orthopedic exercise device. A 10-minute rest period is provided between each assessment. If the participant wishes, additional rest time is allowed and recorded in the case report form. The assessments include the 10-Meter Walk Test, the 6-Minute Walk Test, the Timed Up and Go Test, and the Berg Balance Scale. These evaluations are conducted in the rehabilitation function testing room on the second floor of the facility under the supervision of the research team (physician and either a physical or occupational therapist). After the evaluations are completed, a usability and satisfaction survey regarding the motorized orthopedic exercise device is conducted.

Inclusion Criteria:

1. Individuals aged 19 or older
2. Individuals who have undergone hip surgery due to hip osteoarthritis, avascular necrosis of the femoral head, or hip fracture
3. Individuals who are at least two days post-hip surgery and are assessed to be medically stable
4. Individuals who have adequate cognitive ability (Korean Mini-Mental State Examination score ≥ 20)
5. Individuals able to sit at the edge of a bed without assistance and stand for 10 seconds regardless of support
6. Individuals who are Functional Ambulatory Category (FAC) score of 1-3
7. Individuals who visited Yongin Severance Hospital, understood the study, and signed informed consent

Exclusion Criteria:

1. Individuals who, after undergoing hip surgery, present with exudate at the surgical site or report symptoms such as heat, redness, swelling, or severe pain at the affected area
2. Individuals who have contraindications for lower limb weight-bearing such as severe joint contractures, osteoporosis, or untreated fractures
3. Individuals who have progressive or unstable brain diseases or neurological paralysis from stroke
4. Individuals who have active infections or open wounds hindering device use
5. Individuals who have significant leg length discrepancies
6. Individuals who have severe deformities or contractures in the lower extremities
7. Individuals who have history of poliomyelitis
8. Individuals inable to maintain seated or standing positions independently
9. Individuals who have severe spasticity (Modified Ashworth Scale grade ≥ 2)
10. Individuals who have bone metastases from cancer
11. Individuals who have severe internal diseases affecting device use (e.g., cardiovascular or respiratory diseases)
12. Individuals who have cognitive impairments preventing cooperation with device use
13. Individuals who have complaints of device-related side effects or potential rehabilitation discontinuation (e.g., severe obesity, skeletal deformity)
14. Patients who are determined to be pregnant or potentially pregnant based on the medical interview
15. Individuals who have any other clinically significant findings deemed inappropriate by the investigator