Design Brief: Thoraco-Lumbo-Sacral Orthotic Brace ...



Design Brief Rev 3.1

Three-Segment TLSO Brace

Team Members:

Dave Hower

Jessica Schaberl

Anjani Ravindra

Kimberly Zawrotny

Revision Log:

|Date |Rev |Changes Made |Signed |

|10/12/06 |1.0 |Initial Document | |

|12/15/06 |2.0 |New Design Idea | |

|1/30/07 |2.1 |Revision Log Added | |

|4/1/07 |3.0 |Design and Testing Updates | |

|4/13/07 |3.1 |Grammatical Revisions | |

Problem Statement

Many people require the use of a thoracic lumbar sacral orthotic (TLSO) brace to fully recover from either a spinal injury or spinal surgery. The TLSO brace completely surrounds the torso and inhibits all bending and twisting of the upper body. Proper use of the TLSO brace aids in the healing process of the spinal cord. Without the brace, the patient must remain in bed with very limited mobility and no pressure applied to the spine.

There are many different designs for the TLSO brace. The design that is used most often is a two piece brace that consists of a front half and back half. The two halves are relatively similar in shape; they are both flat in the center and then curve to fit around the patient’s sides, much like a “U”. The sides of the front half overlap the sides of the back half, which forces the patient to put the back half on first. The two halves are then tightened around the patient by three adjustable Velcro straps on each side of the brace.

While the TLSO brace described above can be of significant benefit to patients recovering from spinal injuries and surgery, there are some difficulties associated with its use. The major problem with the TLSO brace is that it must be put on while the patient is lying down, which is difficult and time consuming. Currently, putting the brace on involves “log rolling” the patient onto their side and then positioning the back half of the brace by sliding the side of it under the side of the patient. This step is the most difficult part of putting the brace on; one nurse may struggle to perform this task alone, and it is nearly impossible for a patient to perform it themselves. After this step is completed, the patient must be rolled back into their original position to secure the brace and check if it is aligned correctly. If alignment is improper, the patient must again be rolled to readjust the brace. When the back of the brace is in place, the front piece is placed on the abdomen and strapped onto the patient. Throughout this entire procedure, the patient must be kept straight without any twisting or bending. Oftentimes, to avoid this lengthy and potentially painful process, nurses will sit patients up to put on the brace. Patients who live alone are also encouraged to put the brace on sitting up. Unfortunately, sitting up detracts from the intended function of the brace since the spinal cord is already experiencing a load due to gravitational effects before the brace is put on.

Such incorrect brace placement can hinder and delay the healing process, decrease the patient’s mobility and delay the patient’s discharge from the hospital, causing additional expenses. Providing a simple means of correctly putting on the brace would increase the patient’s ability to a have a safe and speedy recovery with minimal pain. By decreasing the period of time that it takes to become mobile and correctly protected from further injury, the quality of life of patients recovering from spinal procedures will be improved.

In order to improve the ease of TLSO brace placement for patients and hospital staff, the brace will be redesigned. Several different designs were considered, including using different materials, different connecting mechanisms, or introducing openings in the front or back pieces of the brace. However, none of these potential changes removed the need of sliding the brace under the patient. A better means of redesigning the TLSO brace is to split the back piece of the brace into two segments. These segments will connect to the front piece with hinges and to each other with three straps. With this new design, a new and easier placement procedure could be followed. The front piece would first be correctly positioned on the patient. The patient would then “log roll” onto their side so that half of the back could be placed down over the exposed side of the patient. The patient could then roll onto their back again, continuing on to their other side so that the last piece of the brace may be placed. The brace could then be fastened with three straps across the back. The patient would now have the TLSO brace correctly placed around their torso without needing to force the brace under the body.

While the patient benefits from the use of a TLSO brace, he or she is not necessarily the customer for this product. The doctor is responsible for prescribing the brace. Because of this, clinicians must be convinced that the redesigned TLSO brace provides a viable alternative to the traditional bi-valve brace. Further, the redesigned TLSO brace may help the hospital staff by decreasing the difficulties they have with correct brace placement. Overall, redesigning the brace will enhance the brace’s efficiency by increasing the ease of correct placement without compromising its function.

Key Functions

The proposed design utilizes a TLSO brace with three segments. All of the segments of the new brace design are attached, with the sides anchored to the front by hinges and connected in the back by three straps. The hinges must be separated from the interior of the brace by sufficient material to prevent pinching the patient when the side pieces are being moved.

The main difficulty associated with the bi-valve brace is the difficulty of manipulating the single, rigid back segment underneath the patient. In order to remove this difficulty, the proposed design has two side segments in place of a unified back piece. These are easier to maneuver around the patient. As the bulk of support and immobilization in the TLSO brace comes from the front piece, the divided back should not interfere with the functionality of the brace.

The proposed three-segment design also lessens the amount of rolling required of the patient. Rolling is done by the patient in the first attempt to place the back half of the standard TLSO brace, and then again for every readjustment that must be made. This movement can cause discomfort or pain. With the proposed design, the front section is placed in the proper position initially, allowing the back pieces to fall into place without readjustment. Thus, rolling is minimized and the amount of time spent putting the brace on is decreased.

Constraints

The TLSO brace is a truncal orthosis, and as such is considered a Class 1 device by the FDA as stated in 21 CFR 890.3490. The same is true for predicate devices of the TLSO brace, such as the Orthomedic Lumbar Flexion Brace and Vertebrace Spinal Support. Thus, the brace is exempt from premarket notification requirements. For the purposes of the Senior Design Class, 21 CFR 820.30 regulations for medical device quality management systems will be followed. Further, the design must be able to be translated into a prototype in 6 months.

In addition to regulatory and course-related restrictions, several specific constraints apply to the brace. First, the TLSO brace must be able to be placed without causing undue pain to the patient. Due to the new design’s hinges and openings, precautions need to be taken to prevent any pinching. Further, the TLSO brace must not cause the patient to move into a position that puts weight on the spine. According to the criteria for allowed positions of patients following spinal surgery, the patient must not bend at an angle greater than 60° to the horizontal. The process of putting on the brace must not cause changes in spinal alignment that will cause pressure and pain for the patient.

Another constraint for our brace is that it must be of similar material to the current brace. Since this material may come into contact with the skin, the brace cannot be made of substances that may irritate the skin. The material should also be able to withstand standard ambient temperatures (-10°C to 110°C) and not crack or break apart during normal usage. In addition, like current TLSO brace designs, there cannot be sharp parts protruding from the brace. All edges should be rounded to the proper degree in order to avoid injury to the patient.

A third constraint is that the brace must be able to withstand contact with typical agents encountered in a hospital. For example, the outer covering of the brace must not degrade when it comes in contact with typical cleaning or biological substances common in hospital rooms. These substances include but are not limited to isopropanol, bleach, Sporicidin, ammonia, water, saline, blood or other body fluids. This constraint ensures that the brace can be effectively cleaned in accordance with hospital standards, and thus be approved for use in hospital rooms.

Further constraints require the TLSO brace to be portable, easily stored, and small enough to allow the patient easy maneuvering in both a hospital room and a bedroom. These constraints are necessary because the brace will not benefit a patient in the hospital or in the home if it is too bulky to be easily integrated into these environments.

Criteria for Success

In order for our proposed design to be a viable remodeling of the TLSO brace, it must perform the same function as the current TLSO brace, providing the same degree of spinal support and immobilization. Also, the newly designed brace must be easier to put on the patient, both by nurses in the hospital and by patients alone.

Three ways to establish whether the ease of brace placement has been improved by the proposed design have been developed. First, timed trials will be conducted utilizing Hanger Orthotics’ facilities. A Hanger employee with experience putting on TLSO braces will be timed while placing the traditional bi-valve brace on a person. Then, the process will be repeated with the new brace. Ideally, the new TLSO brace will take a lesser amount of time to be placed on the person. By comparing the times of these two trials, it will be possible to determine whether or not this is true.

A second time test will compare the time it takes to put the bi-valve brace on oneself versus the three-segment brace. The ‘patient’ will attempt to place the bi-valve TLSO brace while in the proper supine position. The test will be repeated using the three-segment TLSO brace. Each brace design will be placed three times, and the times compared to determine which brace can be put on faster.

A third test will quantify the amount of rolling required to properly position the three-segment TLSO brace, as compared to the bi-valve brace. During the self-placement time trial described above, the number of times the ‘patient’ needs to log roll in order to position the brace will be recorded for each test of each brace. A full log roll will be considered a motion that brings the ‘patient’ entirely onto one side. A half log roll will be considered a motion that only involves partial shifting of weight onto one side. The amount of log rolling required to put on each brace will be compared to determine which brace is easier to put on.

While beyond the scope of this class, further testing should be done with actual patients in need of TLSO braces. Patients would be asked to place both the bi-valve and three-segment TLSO brace. They would then be asked which brace is better in terms of ease of placement, pain caused by placement procedure, and fatigue caused by placement procedure. This survey would help determine problems associated with the use of the TLSO brace on patients with limitations resulting from spinal injury.

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