Advanced Passive Motion Machine (APMM) for Rehabilitation of Patients with Lower Limb Ailments-An Physio-mechanical Approach

Abstract

Lower limb impairments due to injuries, surgeries, or neurological disorders often require long-term physiotherapy. Continuous Passive Motion (CPM) devices have traditionally been used to facilitate early joint mobility. This paper presents an Advanced Passive Motion Machine (APMM) for rehabilitation of patients with lower limb ailments. The design integrates programmable motion control, safety feedback mechanisms, and adaptable limb support. APMM focuses on modularity, real-time feedback, and cost-effective manufacturing. Simulation and initial clinical trials show promising results in improving rehabilitation outcomes.

Introduction

Continuous Passive Motion (CPM) therapy is widely used in orthopedics and physiotherapy to restore joint range of motion (ROM) after surgeries like total knee replacement (TKR) and hip surgery. CPM is particularly helpful for patients unable to achieve sufficient ROM manually, as machine-assisted motion provides consistency, reduces pain, and sustains therapy longer. While CPM is common for knees, limitations exist for hip and ankle rehabilitation, especially for movements like hip abduction, adduction, internal and external rotation.

Objective of Research:
The research focuses on developing an Advanced Passive Motion Machine (APMM) that can:

• Treat hip, knee, and ankle injuries in a single device.

• Provide precise, adjustable motion control for individual patient needs.

• Allow rehabilitation for bedridden patients while preventing fixed flexion deformity (FFD).

• Be cost-efficient, lightweight, and space-saving.

Significance:
Lower limb injuries (hip, knee, ankle) and surgeries are increasing globally, affecting mobility and quality of life. Current rehabilitation methods are often inefficient, inconsistent, and unsuitable for bedridden patients. APMM aims to overcome these challenges, offering improved comfort, precise motion, and better patient outcomes.

Design Features:

• Bed-cum-Chair Configuration: Adjustable for lying, sitting, Trendelenburg/reverse Trendelenburg positions.

• Therapy Mechanisms:

  • Hip: Flexion up to 45°, abduction/adduction 0°–35°.

  • Knee: Flexion 0°–45° to prevent FFD.

  • Ankle: Three degrees of freedom for plantarflexion, dorsiflexion, inversion, and eversion.

• Adjustable Components: Frame lengths accommodate different patient bone lengths (hip: 30–60 cm, ankle: 30 cm).

• Controls: Function keys operate actuators at constant speed for precise therapy.

• Capacity: Standard dimensions (450 mm height, 400 mm width, 2000 mm length), weight capacity 500 kg.

Methodology:

• Ergonomics applied in design.

• Mechanisms synthesized for hip, knee, and ankle therapy.

• CAD models created to standard specifications.

• Integration of sensors and synchronous motors for controlled movement.

Conclusion

The Advanced Passive Motion Machine (APMM) represents a viable, adaptable solution for lower limb rehabilitation. Its modular design and real-time monitoring enable safer and more efficient therapy. Future work includes integrating wireless data transmission and AI-based motion adaptation.

References

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Copyright

Copyright © 2025 Dr. A. P. Ninawe, Dr. A. V. Vanalkar, Dr. A. M. Badar, Dr. S. Jaju . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.