Office of Technology Transfer – University of Michigan

Lower Body Load-Bearing Passive Exoskeleton

Technology #6376

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Hitinder S. Gurm
Managed By
Janani Ramaswamy
Licensing Specialist, Medical Deviceses 734-763-9081
Patent Protection
US Patent Pending

Lower Body Load-Bearing Passive Exoskeleton Physicians who perform minimally invasive procedures with the assistance of real-time radiography often endure sustained flexed positions while wearing bulky shielding garments called leads. Often these physicians experience fatigue, numbness, and the development of severe back problems, which can lead to medical leave, loss of productivity, and medical expenses. Soft belts and rigid corsets offer spinal offloading, however studies demonstrate that the use of commercially available back belts does not reduce the likelihood of back injury. Custom-made orthoses are more effective than back belts, but are expensive and can increase back postural muscle activity and promote muscle fatigue. Other lead support systems effectively minimize loading on the user, but require costly modifications to the operating room that can reduce the workspace volume. Therefore there is a great interest in developing low cost devices that effectively minimize the weight placed on physicians by leads without impairing mobility and operating room function.

Load Bearing Apparatus for Lead Suits in Radiation Therapy

The proposed technology closely resembles full-leg polio braces that are joined with a band at the waist. Adjustable length rods span the thigh and calf of each leg with rotating joints at both the knee and hip level. At the knee and ankle soft cuffs encircle the leg and attach to corresponding points on the structure located at the knee. The structure on each leg terminates in rubberized feet that contact the ground at the same level as the foot. At the waist, the two leg structures are joined to a rigid, padded belt that partially rests on the hips and the weight borne by the structure is distributed down the leg structures and to the feet of the device. The belt serves as a mounting point for the leads, which go over the shoulders, and further reduces any weight borne by the body of the user of the device. The device has an unlocked state during which the joints are free to rotate so that the user can walk almost normally and assume various positions in order to perform procedures. Once the user is in the desired position they can switch the device to a locked state during which the joints hold their rotational position and provide rigid support and transfer most of the weight from the user to the floor. The user can alternate between locked and unlocked states to allow movement.


  • Ergonomic support for transport of heavy garments or materials
  • Balance and fall protection
  • Disability and mobility assistance
  • Injury rehabilitation


  • No modification of operating room required
  • No intrusion into operating space
  • Allows near-normal mobility
  • No extra sterilization required
  • Can be used with existing leads
  • Can be tailored to fit several users