Ballert Orthopedic :: Newsletters and Articles

Are Off-the-Shelf TLSOs Helpful or Harmful?
By Gene Bernardoni, CO
President and Owner, Ballert Orthopedic of Chicago

Since they were first developed in the early 1950s, custom molded TLSOs have come to be accepted among neurosurgeons and orthopedic surgeons as the best means of controlling spinal motion in post-surgical and trauma patients. A number of studies have since been published demonstrating that superior alignment and triplaner motion control can be achieved with custom molded TLSOs as compared with various off-the-shelf (OTS) spinal orthoses. (See Bibliography.)

Recently, a number of companies have begun to market prefabricated (OTS) spinal supports, claiming that they are equivalent to custom molded TLSOs. After evaluating some of the leading brands of OTS TLSOs with my professional staff, other certified orthotists, and a number of orthopedic surgeons and neurosurgeons, I have come to the conclusion that with regard to biomechanical control of motion, patient compliance, and overall cost, the custom-molded TLSO remains superior to the OTS versions, and should remain in most cases the preferred option for post-surgical and trauma patients. If, however, the custom molded high-profile or low-profile (which some OTS manufacturers call an LSO) TLSO is considered over-bracing in light of improved instrumentation, and less motion control is needed, a number of less expensive options exist, including the standard LS corset. In what follows, I explain the reasoning behind our conclusions.

Biomechanical Considerations

In general, custom orthoses fit the patient more intimately than OTS orthoses by virtue of the fact that they are molded to each patient’s body. In contrast to the completely circumferential custom-molded TLSO, the OTS spinal support usually consists of a shallow anterior and posterior panel connected with adjustment straps and/or thin plastic tongues, or an anterior opening similar to an LS Corset. Although their manufacturers may claim biomechanical equivalence with custom appliances, this is not true. Some OTS appliances may approach the custom molded with regard to intracavitary pressure and kinesthetic withdrawal, but they are by no means equivalent in controlling triplaner (the new buzz word) motion; in fact OTS appliances focus on flexion and extension only. Even so, in many cases, because of the soft shell and/or anterior opening, the flexion extension of OTS appliances is compromised in comparison with custom orthoses. In virtually all cases, OTS orthoses do not or very poorly control lateral flexion and rotation, while custom orthoses are able to control these motions quite well.

Why is it that OTS orthoses fail to achieve the triplanar motion control of custom-molded TLSOs?

	Immobilization Saggital plane motion. Sagittal plane motion is controlled by the anterior and posterior panels of the orthosis working together. The height of the panels (vertical lever arm length), the stiffness of the material from which the orthosis is made, and the integrity of the panel all combine to inhibit motion. The anterior panel inhibits spinal flexion and the posterior panel inhibits spinal extension. One can easily see, therefore, that a high anterior panel will prevent anterior flexion of the lumbar and/or thoracic spine while a high posterior panel will prevent posterior extension of the thoracic and/or lumbar spine. In both cases the opposite panel or a simple narrow strap will set up a three-point ressure system (Fig. 1).
Fig. 1.—Three-point pressure system
	Many OTS spinal orthoses have a posterior shell that is higher than the anterior shell, thereby encouraging a flexion moment (see Fig. 2). This low anterior trimline is contraindicated in most non-operative or post-surgical conditions. For example, a superior anterior trimline at or slightly below the superior end of a posterior fusion with instrumentation is not only ineffective in prohibiting flexion at the most vulnerable point of the fusion, it also acts as a fulcrum that could increase the flexion force and lead to failure, as shown in Fig. 2. Most surgeons agree that a posterior implant is most vulnerable by uncontrolled anterior flexion. The implant is best protected by maintaining a neutral spinal alignment and prohibiting anterior flexion.
Fig. 2.—Aspen low-profile  appliance with extender strap (A).

In many cases a longer anterior shell with a shorter posterior shell is indicated to encourage an extension moment (see Fig. 1). Only in disease conditions such as spondylolysthesis or those conditions where it is beneficial to unload the posterior column, such as spinal arthritis or nerve root entrapment, is it indicated to encourage a flexion moment. Most OTS spinal supports do not even address the fact that different conditions require different sagittal plane alignments.

Coronal plane motion The lateral panels of an orthosis control coronal plane motion. These panels act in the same way as the anterior and posterior panels described above. The longer or higher the panel, the better can motion be controlled. Lateral flexion is more limited by the anatomy (locked facet joints with normal lumbar lordosis) than is anterior flexion.

	The lateral panels of an Aspen LSO are also lower (the overlapping outer panel is the effective lateral height, not the inner panel and foam liner — see Fig. 2) than on an LS corset or a low-profile TLSO, and this deficiency allows for greater lateral flexion, which may be a detriment to patient outcomes. Those OTS spinal supports which use only straps or thin polyethylene tongues laterally also cannot control lateral flexion as well as the firm lateral panels of a custom molded TLSO. (See Fig. 3.)
Fig. 3.—VertAlign with polyethylene tongue.
	Transverse plane motion. The most effective means of controlling rotation is a high-profile trimline with subclavicular extensions that act with the contralateral ASIS. (See Fig. 4.) The high trimline is necessary to control motion in both the thoracic and lumbar spine from T-4 to L-4. Rotation in the L-5 S-1 area is best controlled with a low-profile TLSO with hip spica. In a low-profile TLSO it is necessary to encompass the ribs and have a good lock on the pelvis and ASIS to control rotation (see Figs. 3 and 4).
Fig. 4.—Derotation principle: custom molded TLSO: contact at ASIS and subclavicular area.

For this reason an LSO below the ribs will not control rotation as well as a custom molded TLSO that encompasses the ribs, because the attempted rotation is stopped by the contralateral ASIS. Many OTS TLSOs do not cover the ASIS (see Fig. 3). In the PSF with or without instrumentation in the high lumbar and thoracic regions, rotation is the second most detrimental force that can lead to failure. Subclavicular trimlines are needed in Harrington rod instrumentation to stop rotation which could allow the superior hooks to dislodge. With the Aspen high-profile TLSO the thoracic section is connected to the pelvic section by means of the round rods which cannot control rotation because the rods twist, allowing rotation at the junction of the two sections. Many surgeons believe that this is not as critical in newer implant systems which use screws at each vertebral level, although gross twisting motions (rotation) can put large torque loads on the screws at the level of maximum spinal rotational motion (usually worst at the T12-L1 junction).

The series of photographs in Figure 5 graphically illustrates the superior ability of custom TLSOs over OTS braces when it comes to controlling spinal rotation. In the top panel, the unbraced subject lifts his shoulder off the exam table (horizontal flexion) while keeping his spine and posterior ribs flat on the table. In the middle panel, the subject next attempts to maximally rotate off the exam table while wearing an Aspen TLSO with his pelvis held flat on the exam table. And finally, in the lower panel the subject attempts to maximally rotate as above with a custom molded TLSO. As one can easily see, while pure shoulder motion is allowed under all scenarios, shoulder and spinal rotation measuring roughly 80 degrees is allowed with the Aspen TLSO (i.e., 50° of spinal rotation).

Fig. 5.— The unbraced subject in the supper panel is being demonstrates pure shoulder motion (30°) Wearing the Aspen brace in the middle panel, the subject adds spinal rotation of roughly 50°. Wearing the custom molded TLSO  in the lower panel, the subject ‘s spinal motion is restricted to 0°. Only horizontal flexion of the shoulder is visible.

Angulation

Kinematics. Although much attention has been given to the ability of spinal orthoses to reduce planar motion, more current thinking has clinicians considering the ability of orthoses to change planar alignment, specific to injury or instability.

Nonoperative fractures. It may be derived from the literature that orthoses for the nonoperative management of spinal fractures must be able to hyperextend the injury site. That means they should yield a radiographically measurable increase in height of the front of the spine at the fracture sight. This in turn closes facet joints posteriorly and tenses the anterior longitudinal ligament and anterior annulus, thus resisting progression of the deformity while immobilizing the injured site in all three planes. The orientation of these biological components being compressed posteriorly and tensed anteriorly will be the best method of immobilizing the nonoperative spinal fracture. Containment of the torso in a plastic tube (such as is afforded by all OTS appliances, does not guarantee immobilization or resistance to injury progression.

Spondylolisthesis/Stenosis. The inverse is true for these patients, but for different reasons. The posterior aspect of the spine requires tension while the anterior aspect requires compression. Whereas this opens facet joints and transfers loading on the disc, this pathology is neurocompressive and the hyperflexion is necessary to decompress neural elements that are trapped by anatomical artifacts. This is not a “classical” instability and must be hyperangulated into flexion. For fractures and stenosis/spondylolisthesis, it is important to hyperangulate the spine to the maximum potential of each patient, and we question the ability of OTS spinal orthoses to achieve optimal angulation.

Post-operative/post fusion. The task of a surgical implant is to immobilize a segment while a bone graft grows into a solid fusion mass, thus obliterating motion, over time, at that segment. The vulnerability of any implant is that the implants are always significantly stiffer than the bone that they are attached to. It is safe to say that a post-operative orthosis that does not perfectly match the post-operative geometry of the spine may be creating artifact forces that may influence loosening of an implant. This is especially true for the elderly who may already have compromised bone mineral density, thus increasing the differences between the bone and implant stiffnesses.

In summary, most OTS orthoses are made in fixed geometries that are not hyperextended or hyperflexed, and are not able to reliably match a post-operative fusion construct alignment.

Fit Considerations

Fig. 6.—One Size Fits All? You wish!

Most manufacturers of OTS TLSOs offer a choice of only several sizes. They usually don’t consider differences in lordosis and rarely consider gender anatomical differences or obese patients (Fig. 6). Some attempt to compensate for the restrictive choice of sizes by using shallow concave anterior and posterior shells and a series of straps or straps and thin polyethylene tongues to join them (Fig. 3). Others use an anterior opening (like an LS corset) with extender strap to accommodate different circumferences. (See Fig. 2.)  In terms of fit, there are several drawbacks to this approach. First, a TLSO with shallow concave shells is ineffective in controlling the movement in overweight and obese patients, a group estimated at upwards of 70% of the adult U.S. population.

	For example, OTS spinal supports do not include a good pouch for pendulous abdomens, while a custom-molded orthosis can easily accommodate them. The failure to accommodate the abdomen prevents contact at the sternum and symphysis pubus, which compromises control of motion, especially flexion extension. (See Fig. 7.) The effective vertical lever arm length measures from the superior most contact point to the inferior most contact point. An abdominal “spare tire” acts as a ball-bearing to a flat anterior panel and does not allow the orthosis to make contact on the sternum or symphysis pubis. A custom-formed pouch also allows compression and intracavitary pressure without allowing the excess tissue to slip under the anterior inferior edge of the TLSO.
Fig. 7.—Flat anterior shell does not fit abdomen.
	In a custom molded TLSO, such a pouch also keeps the orthosis from migrating superiorly since the iliac crest pads or indentations will not work as well by themselves in an obese person. In the OTS spinal support, by contrast, the absence of the pendulous abdomen pouch forces excess tissue to push under the inferior edge of the anterior shell (see Fig. 8). This may well cause the orthosis to migrate superiorly, while forfeiting the biomechanical principle of elevating intracavitary pressure to provide axial unloading.
Fig. 8. Flat anterior shell causes excess abdominal tissue to escape under shell.

In the custom molded TLSO we normally create a deep indentation over the iliac crest and continuing medial to the ASIS. This is something that is missing in OTS spinal supports (see Fig. 9). Achieved by modifying a deep groove in the positive model of the patient and/or adding a foam crest pad, such an indentation is extremely important in preventing the migration of the orthosis superiorly and preventing rotation of the orthosis on the body.

Fig. 9 - The Cybertec appliance does not conform to the patient's waist.

In custom TLSOs we are abler to modify this waist groove deeply and may even add foam crest pads to insure a good lock on the pelvis. If these waist grooves are not deep enough or the patient wears the orthosis too loose, the whole orthosis will migrate configuration and depth of the waist modification is determined by the anatomy of the patient and also the firmness of the patient’s tissue. This can only be ascertained by actually seeing, measuring and casting the patient. Since this cannot be done for OTS spinal supports, their waist grooves are very shallow or do not exist at all, allowing these supports to migrate when the patient sits or to rotate on the patient. In either case the orthosis is no longer in the desired position to control motion at the specified vertebral level.

This is not to rule out OTS spinal orthoses in all clinical situations. On the contrary, for some non-surgical conditions (such as anterior compression fractures), where hyperextension of the patient is desirable, a high-profile spinal orthosis such as the Jewett Hyperextension Brace or the CASH will work quite well. Both of these are more economical than the new crop of OTS “TLSO’s.” Orthoses that provide kinesthetic withdrawal or intracavitary pressure for axial unloading such as LS corsets, Warm ‘N Form, Aspen LSO, Cybertech LSO, etc. are also appropriate within their indicated limitations. The Aspen and Cybertec, however are substantially more expensive than the others.

In summary, while the manufacturers of OTS spinal supports claim that they are biomechanically equivalent to custom molded TLSOs, this is usually only true with regard to kinesthetic withdrawal and intracavitary pressure. And although they may somewhat control motion, they are not able to control motion in all planes as well as the custom. Their failure to address adequately the anatomical gender differences, the large number of overweight and obese patients, and kyphotic and lordotic differences between patients compromise their ability to control motion or even spinal alignment.

Compliance

It is self-evident that an orthosis cannot do the therapeutic job it is designed to perform unless the patient wears it. Patients tend to avoid wearing their braces for one of three reasons: (1) The brace is uncomfortable to wear; (2) it causes embarrassment; or (3) the patient does not understand how to wear the brace properly.

The comfort factor. Because they are custom formed to the patient’s body, custom molded TLSOs are usually more comfortable to wear than are OTS orthoses. The custom TLSO will restrict motion, which is what it is designed to do. It is therefore necessary to explain this to the patient. The motion restriction may be something the patient does not like at first, but they will usually adjust to it in a short time. Although patients sometimes complain that the plastic is hot, it is not hotter than those OTS orthoses which use thin polyethylene and 3/8 inch foam liner (Aspen LSO). Cybertec is perforated in an attempt to allow heat dissipation. We address this in custom molded TLSOs by drilling holes to dissipate the heat. From the standpoint of heat, LS corset or open-frame orthoses are coolest. And even if an OTS brace is marginally more comfortable, the physician must carefully consider the trade-off between comfort and effective restriction of motion.

The embarrassment factor. Most OTS orthoses are bulkier than custom orthoses and do not lend themselves to being worn under clothes. A TLSO with a liner can and should be worn under clothes. Although it doesn’t happen often I have been able to accommodate patients without compromising function of the orthosis. I once made at custom molded hyperextension TLSO to be worn under a sleeveless gown (see Fig. 10). With the exception of tight-fitting clothes like jeans most people have clothes that will fit over custom orthoses. We instruct patients to wear the TLSO with only a stockinet (provided with all TLSOs), T-shirt or tube underneath and to put their clothes (including panties or shorts) over the TLSO.

Fig. 10.—Custom molded hyperextension TLSO with aluminum anterior bar inside plastic for ribidity.

The donning/doffing factor. Because they depend so much on a multiplicity of straps, OTS orthoses are much more complex for the patient to put on and adjust than are custom made orthoses. In an effort to compensate for the limited number of sizes, manufacturers of OTS orthoses have added a dizzying series of straps and buckles intended to permit a iner-tuned fit. The Aspen TLSO, for example, has seven straps to attach and adjust. In the case of the Aspen TLSO or LSO, the straps make it very difficult to learn to apply properly, even for trained orthotists. This complexity means that patients are often unable to adjust their orthoses for maximum benefit, and may give up wearing them entirely out of frustration with all the straps that need adjusting.

While all orthoses require some patient training, we have tried to eliminate patient guesswork in application by using labeling, straightforward instructions, and the characteristics of the orthosis itself, so that the orthosis can be applied time after time with proper orientation and the same degree of compression.

Cost

In light of these biomechanical and compliance deficiencies, it is surprising to learn that OTS spinal supports cost more than custom molded TLSOs. The cost to the hospital or to the patient of an OTS appliance is frequently higher than a custom orthosis. For example, in the case of the Aspen TLSOs, the cost to the hospital is $300 to $400 more than the custom TLSO, including the cost of follow-up visits. When an Aspen is used in place of an LS corset or a Warn ‘N Form, the former can cost $500 to $600 more. And when the hospital cannot pass along the cost of the item to the patient’s insurance, as in a DRG or per diem stay, the cost falls directly to the hospital’s bottom line. Although we do not consider cost at the expense of clinical outcome we would be remiss to pay dearly for poor or unknown clinical outcomes.

Liability

Having the knowledge that a particular orthosis is not as effective as another in controlling motion and using the inferior orthosis may expose one to liability in the event of the failure of a fusion, further progression of an injury, or improper alignment causing neurological impairment. Usually a certified orthotist is called into court cases as an expert witness and his testimony is typically given greater weight over other witnesses who do not have a degree or license in orthotics. In Chicago, the Director of the Orthotic Program at Northwestern University Prosthetic and Orthotic School is often called as an expert witness.

A second possible area of vulnerability in any court hearing is the use of a non-certified or non-licensed orthotist in the fitting of an orthosis. There are specific rules dictated by the American Board for Certification and the Illinois Orthotic and Prosthetic Board as to the various types of supervision required when allowing medical personnel other than a certified orthotist to measure for and fit an orthosis. One should be aware that salespeople for various manufacturers of orthotic devices are usually not certified or licensed orthotists and, in fact, have no training whatsoever other than sales training. Therefore their canned spiel is oftentimes memorized and not even understood by them.

Conclusion

In conclusion, while economically priced OTS orthoses can and should be used under certain prescribed conditions to satisfy carefully described treatment objectives, they by no means can control motion as well as custom molded TLSOs. We need to take care that our patients do not pay for expensive products that cannot help to ensure the best possible clinical outcome. The custom molded TLSO provides superior fit and support relative to its OTS relative, and induces better compliance among its wearers because of its simplicity. It is also the most cost-effective option.

Acknowledgment: We would like to thank.

Bibliography

Cholewicki, J., et al. “Lumbar Spine Stability Can Be Augmented with an Abdominal Belt and/or Increased Intra-abdominal pressure.” European Spine Journal 1999; 8(5):388-95.

Hall, J.E., Miller, M.E., Cassella, M.C., et al. Manual for the Boston Brace Workshop. Boston, MA: Department of Orthopedics, Children’s Hospital; 1976.

Harrington, P.R. “Treatment of Scoliosis, Correction and Internal Fixation by Spine Instrumentation.” J Bone Joint Surg (Am). 1962 44:591-610.

Knight, R.Q., et al. “Comparison of Operative versus Nonoperative Treatment of Lumbar Burst Fractures.” Clinical Orthopedics. 1993, Aug; (293):112-21.

Lorenz, M., et al: “Instability and Mechanics of Implants and Braces for Thoracic and Lumbar fractures.” Spinal Trauma, 276-7.

Gene Bernardoni, CO, President of Ballert Orthopedic in Chicago, is a graduate of the orthotic certificate course at the Northwestern University Medical School Prosthetic-Orthotic Center (NUPOC) and is certified in orthotics by the American Board for Certification in Orthotics and Prosthetics (ABC). Under Bernardoni’s direction, Ballert has become a leader in emergent care in the Chicago area. Bernardoni is on the auxillary staff at NUPOC and is a sought-after lecturer in orthotic applications.

Gene Bernardoni, CO, is the owner and President of Ballert Orthopedic of Chicago.

Thomas M. Gavin, CO is founder, President and Director of Clinical Services of BioConcepts, Inc. in Burr Ridge, Illinois.

Gavin is a graduate of the orthotic certificate course at NUPOC and is certified in orthotics by ABC. He has a vast amount of experience in all areas of clinical orthotics since 1975, spinal research since 1985 and teaching since 1987.

Gavin is also a Research Orthotist in the internationally renowned Musculoskeletal Biomechanics Laboratory at the Veterans Administration Hospital, in Hinsdale, Illinois.