THE CHAMELEON TLSO: A PROTOTYPE

Carol Matsui, B.A., C.O.(c)


There are many scoliosis orthoses on the market these days, each named after its city of origin. Each is designed for optimal fit and correction for EITHER daywear OR night-wear. So far, no one has marketed a scoliosis orthosis, which can be converted to accommodate both positions.

Development of the Charleston Bending Brace has proven that there is an application for an orthosis, which overcorrects while the wearer is asleep. For years, physicians have also used daywear orthoses at night, in an attempt to increase the number of in-brace hours within a 24-hour period. The latter practice has been only moderately successful at best, given that, even at their tightest, daywear orthoses such as the Boston brace can never provide over corrective forces.

The Chameleon TLSO was born out a desire to marry maximum corrective forces with increased wear time options, at a low cost. Physicians and clients alike can potentially benefit from an orthosis which functions as two, at the cost of one. Most government health plans, as well as private insurance will only pay for one device per claim period.

The Chameleon TLSO is a hinged orthosis, which, by a system of straps and/or rigid couplers, is transformable by the client from day to night position. It consists of two or three overlapping articulating segments, connected with either a single axis pivot or a gliding hinge. It is fabricated with a full liner of ¼" thermo-foam, followed by two layers of HDPE, pulled one over the other.

The gliding hinge is the primary feature that distinguishes the Chameleon from other scoliosis TLSOs (see Fig. 1 ). This hinge design allows for 1) rotation in the frontal plane to maximize corrective forces in both upright and horizontal positions and 2) lengthening, which accommodates torso elongation in the horizontal position, and allows for the application of corrective forces higher in the axilla.

Selection criteria for study candidates were as follows:

  • adolescent idiopathic scoliosis curve size of 25-40 degrees, as per Cobb measurementage 10-15 years
  • Risser sign of 0,1 or 2

Two clients have been fitted with this style of TLSO. The first client fit with a Chameleon was R.L., a premenarchal girl with adolescent idiopathic scoliosis, aged 12+9 years at time of diagnosis. She had a 26-degree left lumbar curve with 2+ rotation and an non-rotated 24 degree right thoracic curve. She was casted horizontally in the night-wear position, and her lumbar curve was unbent, it being the primary one. However, corrective forces were applied to both curves.

Cast modifications for the Chameleon proved challenging. It was difficult to get the lateral aspects of the overlapping segments to be congruent and aesthetically acceptable in both day and night positions. Scotch cast mock-ups were used after each modification adjustment, to check congruency and appearance.

Prototype I had two segments, with an anterior and posterior gliding hinge connecting them. The bottom of the hinge was located 2 cm. proximal to the waist roll. Prototype I was dispensed, but later replaced with Prototype II (see Fig. 2 ), which applied more correction to the thoracic curve. In brace films were obtained in both day and night positions, with the following results:

  • Day position (L) lumbar 12 degrees, (R) thoracic 20 degrees
  • Night position (L) lumbar -4 degrees (R) thoracic 10 degrees

 

Figure 2

Subsequently, more correction was added to the upper curve: however, to date, no further in brace films have been obtained. In hindsight, this client would probably have benefited from a Chameleon TLSO with two articulations and three segments, so that correction of the thoracic curve could be adjusted independently.

R.L. and her mother seemed to be very satisfied with the orthosis' fit and flexibility of function. Although her physician does not feel she needs to wear it during the day, R.L. often puts it on after dinner in the day position, and then switches to the nightwear position for bedtime.

The second client fit, J.B., has Spina Bifida, and had two previous TLSOs. Although he didn't fit the original criteria (which included adolescent idiopathic scoliosis) of the study, he was chosen for two main reasons. He and his family were willing participants, and I was interested in applying this style of TLSO to the Spina Bifida population (this makes up a large percentage of the Bloorview MacMillan Centre caseload). Due to his L4-5 lesion, which caused a left kink of 22 degrees at that level, as well as a long right C-curve of 40 degrees, it was felt that a two hinge, three segment TLSO was appropriate (see Fig. 3 ). The two lower segments were articulated via a single axis pivot, and the proximal segment was attached using a gliding hinge. The double hinge design greatly increases the potential for movement between the segments, and requires careful placement of straps and removable rigid couplers to ensure stability during wear. In brace films have yet to be obtained for this client. However, it is anticipated that the double hinge design will allow for good results at both the lesion level and the thoracic apex.

Figure 3

Client J.B. and his mother appear to be interested in and satisfied with the new TLSO design. They have been instructed in the use of this slightly more complex transformable TLSO, and are competent in switching positions.

We plan to continue to fit Chameleon TLSOs on selected clients with scoliosis. Design challenges requiring more attention include:

  1. cast modification which allows for smooth transitioning between day and night positions
  2. a quick release rigid coupler for double hinge Chameleons, to maintain night positioning when a substantial over correction is possible
  3. tongue designs for the anterior opening
  4. minimal, effective strapping

Once these challenges have been met, a multicentre study is planned to gather statistics regarding the efficacy of the Chameleon TLSO. Would anyone interested in participating in such a study please contact

Carol Matsui, C.O.(c)Orthotic Services,
Bloorview MacMillan Centre,
350 Rumsey Road,
Toronto Ontario Canada
M4G 1R8

Phone 416-424-3826
Fax 416-424-3821

Email address:

cmatsui@bloorviewmacmillan.on.ca

This research project was funded by the Bloorview Children's Foundation.

Orthotic Services, Bloorview MacMillan Centre, Toronto Ontario Canada