Review of Current Spinal Robotic Orthoses

Abstract

Osteoporotic spine fractures (OSF) are common sequelae of osteoporosis. OSF are directly correlated with increasing age and incidence of osteoporosis. OSF are treated conservatively or surgically. Associated acute pain, chronic disabilities, and progressive deformities are well documented. Conservative measures include a combination of initial bed rest, analgesia, early physiotherapy, and a spinal brace (orthosis), with the aim for early rehabilitation to prevent complications of immobile state. Spinal bracing is commonly used for symptomatic management of OSF. While traditional spinal braces aim to maintain the neutral spinal alignment and reduce the axial loading on the fractured vertebrae, they are well known for complications including discomfort with reduced compliance, atrophy of paraspinal muscles, and restriction of chest expansion leading to chest infections. Exoskeletons have been developed to passively assist and actively augment human movements with different types of actuators. Flexible, versatile spinal exoskeletons are designed to better support the spine. As new technologies enable the development of motorized wearable exoskeletons, several types have been introduced into the medical field application. We have provided a thorough review of the current spinal robotic technologies in this paper. The shortcomings in the current spinal exoskeletons were identified. Their limitations on the use for patients with OSF with potential improvement strategies were discussed. With our current knowledge of spinal orthosis for conservatively managed OSF, a semi-rigid backpack style thoracolumbar spinal robotic orthosis will reduce spinal bone stress and improve back muscle support. This will lead to back pain reduction, improved posture, and overall mobility. Early mobilization is an important part of management of patients with OSF as it reduces the chance of developing complications related to their immobile state for patients with OSF, which will be helpful for their recovery.

Keywords: active orthosis; exoskeleton; osteoporotic spine fracture; spinal orthosis; wearable robotics.

Figure 1

Standard range of movements for the human lumbar spine.

Figure 2

The principle posterior spinal muscles.

Figure 3

Adapted from Trulife—C.A.S.H. Orthosis.

Figure 4

(Left): Adapted from Alberta Association of Orthotists and Prosthetists. (Right): Adapted from the Steeper Group—Oasis Spinal Brace.

Figure 5

First patented exoskeleton.

Figure 6

The ‘Pitman’ exoskeleton.

Figure 7

The BLEEX exoskeleton.

Figure 8

The MIT exoskeleton.

Figure 9

Men wearing the HAL carrying heavy load.

Figure 10

The ReWalk system.

Figure 11

(a) the PLAD (b) Schematic of the upper body plastic bands with elements under tension (T, 1–6). (Copyright Springer Nature).

Figure 12

The Smart Suit Lite (SSL).

Figure 13

The BNDR.

Figure 14

The LAEVO. 1: rotational chest pad 2: flexible beam 3: spring loaded joint.

Figure 15

(a) dummy user wearing exoskeleton, (b) zoomed-in detail view, and (c) the cable-tension mechanism of applying the spring pushing force on the human lumbar region.

Figure 16

The back support muscle suit (Copyright Springer Nature).

Figure 17

The SPEXOR design (Copyright Springer Nature).

Figure 18

(a) The viscoelastic couplings (b) the outlook of the werable device.

Figure 19

The RoSE.

Figure 20

The S-assist device design. Left: lateral view. Right: view from the front.

Figure 21

The novel concept of the flexible sliding thigh frame.