External spinal orthoses are commonly used in treating spinal disorders, such as osteoporotic or traumatic fracture, spondylolysis, and in postsurgical stabilization. The main goal of a spinal orthosis is to relieve pain and reduce spinal motion. It is designed to allow optimal restoration of the spine to a condition where it can effectively resume its purposes, such as load transfer, protection of the spinal cord, and movement in three planes. A spinal orthosis has five main functions: to serve as a psychological reminder and to offer total contact, three-point pressure, endpoint control, and elevated pressure.1
Several types of spinal orthoses are available, all of which have special mechanical considerations, variable prices (range, €62.00–605.83), and differences in comfort. Every spinal orthosis uses some degree of three-point pressure to maintain the desired position. Orthoses that use pads give excessive pressure on a localized part of the body (e.g., the Jewett brace). Few orthoses achieve endpoint control, which gives a firm grasp of the proximal (thorax) and distal (pelvis) spinal region of interest. Elevated intra-abdominal pressure reduces the net force applied to the spine and reduces some of the stress placed on the spine itself.1 Total contact between the orthosis and the wearer results in an equal distribution of pressure and good control. However, as the spine is surrounded by skin and soft tissues, complete immobilization will never be pursued, especially in obese patients. Besides offering control and pressure, an orthosis serves as a kinesthetic reminder to limit motion or adapt movements to unload the spine. A soft and a rigid orthosis may be equally effective for this purpose.
Despite the widespread use of spinal orthoses in clinical practice, evidence of their efficacy in the treatment of several spinal conditions is lacking. Only a few studies have investigated the capacity of spinal orthoses to immobilize. Hashimoto et al.2 studied the effect of rotational swing in low back pain during golf with sensor-based movement analysis and showed that lumbar extension and rotation angles are decreased in braced condition during golf swing, whereas hip rotation is increased.
Sato et al.3 evaluated the long-term effect of a lumbar orthosis in patients with chronic low back pain and found that patients treated with corset had less pain and increased muscle endurance for a short period. There was no difference in muscle atrophy between patients treated with or without corset.
Schmidt et al.4 investigated the effect of spinal braces by using it as a proprioceptive kinesthetic reminder in osteoporosis and found a beneficial impact on gait stability.
Several studies have investigated the efficiency of braces in fracture management.5–7 It seems that the unbraced condition gives the same clinical and radiological results as brace treatment; however, these studies have their limitations, mainly because of small sample sizes. Therefore, further research with a randomized controlled trial is necessary to objectify best conservative treatment in thoracolumbar spinal fractures.
As there is no general guideline to choose the appropriate orthosis, hospitals use their own directives, which can be quite different. Recommendations for the use of spinal orthoses are mainly based on literature reviews without studies describing objective immobilization effects.8
To our concern, there is no literature comparing the effect on spinal movement while wearing different types of thoracolumbar spine orthoses in daily motion tasks such as gait, stair climbing, and rising from a chair.
There are several validated methods available for movement analysis. Accelerometer-based movement analysis is such a validated, noninvasive, non–time-consuming, inexpensive, and objective method for objective movement analysis in a three-dimensional (3D) view.9,10 It shows the biomechanical response to an immobilization or movement restriction caused by pathologies of musculoskeletal origin. It is easy to use in different settings, such as an outpatient clinic or even at home, for objective motion analysis in daily tasks.
In our clinic, we use the inertia sensor-based motion analysis (IMA) for movement analysis in different pathologies. This method allows us to objectively measure the effect of a brace on the performance of movements, which may provide further insight into the movement reduction of the braces.
The aim of this study was to evaluate and compare movement reduction and comfort of four types of thoracolumbar orthoses compared with normal spinal motion using IMA and questionnaires.
Ten healthy volunteers (6 male, 4 female; age 18–60 years [mean, 27.7 years]) without a history of back pain, musculoskeletal problems, or obesity were included. The Atrium Medical Center (METC Atrium-Orbis) ethics committee approved the study using able-bodied volunteers as research subjects. The subjects were asked to perform several function tasks under five conditions: first, without wearing an orthosis and subsequently, while wearing four different types of orthoses.
Four commonly used orthoses (e.g., bandage, SecuTec Dorso; Jewett, spinal cast) were evaluated (Figure 1):
- Lumbo-assist (Spronken) is a contoured elastic support with anatomical fit and gives support to the lumbar (and low thoracic) spine (price, €62).
- The SecuTec Dorso (Bauerfeind) is a modified orthosis for the support of the lower thoracic and lumbar spine (price, €605.84).
- The Jewett (Spronken) is a thoracolumbar hyperextension orthosis and is designed to unload the anterior column (price, €354.24).
- Spinal cast, dorsal-lumbar corset (OKM system), is a combination of polyurethane rigid foam as a splint and the elastic stocking as bandage surface. The bandage is applied in a soft condition and hardens on the body. It is easy to modify and self-molding, which assures a perfect fit. In addition, it is removable through integrated zippers (price, €236).
Motion analysis was performed using IMA. The sensor was a 3D accelerometer and gyroscope. It was a small (44 mm × 58 mm × 21 mm) and low-weight (45 g) MicroStrain Inertia Link sensor. The sensor measures acceleration (gravity) and angular rate (degrees/s) in three different planes, which are converted to attitudes (degrees).
The inertia sensor was attached on the sacrum (Figure 2), while the following function tasks were performed:
- 1) Gait test: Subjects walked a 10-m distance at preferred walking speed.11
- 2) Sit-to-stand (STS) test: Subjects had to ascend and descend from a chair at preferred speed without using their arms. They started in a sitting position, with their knees flexed in 90 degrees.11
- 3) Block-step test: Subjects stepped up and down a 20-cm wooden block, starting first with the left leg and subsequently repeating it with the right leg.11
- 4) Flexion-extension test: Subjects had to bend forward and backward as far as possible without bending their knees.
- 5) Latero-flexion test: Subjects had to bend as far as possible to the left, followed by bending to the right. Every function task was performed three times, with a 3- to 5-second break in between. Averages of the three repetitions were used for analysis.
All tasks were performed in every condition, starting without wearing an orthosis, followed by wearing one of the four orthoses. A fixed order was used: the bandage, the SecuTec Dorso, the Jewett, and the spinal cast.
Raw data were analyzed using self-developed, validated algorithms.10 Averages were used for analysis. Group comparison was performed using t-test and the least significant difference as post hoc test.
For each task, many specific parameters were derived. Relevant outcome parameters used for analysis are mentioned below:
- 1) Walking speed (distance/walking time) in kilometers per hour (used in gait analysis).
- 2) Step time (time from foot contact to foot contact) in seconds (used in gait analysis).
- 3) Step length (distance/number of steps) in meters (used in gait analysis).
- 4) Variability step time left/right: difference between left/right step times (used in gait analysis).
- 5) (Absolute) bending angle with a forward and backward motion (flexion and extension) in degrees (used in block-step, STS, and flexion-extension test).
- 6) Maximum angular rate bending (angular velocity) in degrees/s (used in block-step, STS, and flexion-extension test).
- 7) Start-sway (swing in anterior-posterior direction) in degrees (used in STS test).
- 8) Pelvic obliquity (lateral sway) in degrees (used in block-step and STS test).
To analyze comfort and subjective immobilization, subjects completed a self-designed questionnaire for each orthosis. The questionnaire consisted of 12 questions concerning disability and comfort. Every question was scored from 1 to 5, with 1 representing total discomfort or total immobilization and 5 representing no discomfort and no immobilization experienced (Figure 3).
In the unbraced condition, subjects walked with a walking speed of 5.33 km/h (±0.64 km/h) and a step time of 0.61 seconds (±0.14 seconds). Mean step length was 0.95 m (±0.23 m), and the variability in step time left/right was 0.13 (±0.099). No effect of wearing an orthosis was found on gait parameters.
In the unbraced condition, the mean bending angle during rising was 42.0 degrees (±6.3 degrees), with a maximum angular rate in forward bending of 1.9 degrees/s (±0.5 degrees/s). Wearing an orthosis had just a small limiting effect on the absolute bending angle, with only a significant reduced bending sway for the spinal cast compared with the unbraced condition (Table 1).
The largest effect on the rising performance of the STS test was shown by a significantly reduced maximum angular bending rate. The spinal cast provided the largest reduction (−0.55 degrees/s), followed by the Jewett (−0.44 degrees/s), the SecuTec Dorso (−0.34 degrees/s), and finally by the bandage (−0.16 degrees/s), which caused the smallest reduction.
During sitting, bending angle in normal condition was 48.0 degrees (±8.9 degrees) with a maximum angular rate of 1.1 degrees/s (±0.4 degrees/s). Only with Jewett brace was the bending angle during sitting significantly reduced and start-sway significantly increased in the unbraced condition.
Normal sway was 0.063 degrees (±0.06 degrees). In all braced conditions, start-sway was increased. However, this finding was only significant during rising with regard to the unbraced condition for the Jewett (an increase of 0.98 degrees). With sitting down, the bending angle and pelvic obliquity were significantly reduced when wearing the Jewett (−8.3 degrees bending angle, P < 0.01; −1.09 degrees pelvic obliquity, P < 0.05, respectively) compared with the unbraced condition (Figure 4).
During stepping up, the bending angle was 9.9 degrees (±2.7 degrees) in the unbraced condition, and the pelvic obliquity was 11.8 degrees (±3.0 degrees). During stepping down in the unbraced condition, the bending angle and pelvic obliquity were 12.54 degrees (±3.08 degrees) and 9.5 degrees (±2.6 degrees), respectively.
The pelvic obliquity was lower in stepping up when wearing an orthosis compared with the unbraced condition (Table 2). A lower pelvic obliquity was also found during block-stepping down when wearing an orthosis compared with the unbraced condition. The largest difference in pelvic obliquity was found in the SecuTec Dorso, while the spinal cast showed the least decrease.
In the normal condition, forward bending was 64.5 degrees (±11.6 degrees) with a maximum bending rate of 1.2 (±0.3). Mean bending backward angle unbraced was 16.8 degrees (±9.8 degrees) with a maximum bending rate of 0.4 degrees/s (±0.2 degrees/s). The mean pelvic obliquity for left and right were 4.5 degrees (±2.5 degrees) and 2.0 degrees (±0.7 degrees), respectively.
Every orthosis, with exception of the bandage, caused a significant reduction in the forward and backward bending angle during the flexion and extension test (Table 3). The spinal cast provided the largest decline in the forward bending angle (46.3 degrees [±14.7 degrees]), while the bandage had the least reduction in the forward bending angle (59.1 degrees [±13.5 degrees]). During backward bending, the SecuTec Dorso showed the largest reduction (bending angle, 11.3 degrees [±5.4 degrees]) and the spinal cast had the least reduction with a bending angle of 13.4 degrees (±6.6 degrees).
Pelvic obliquity seemed to be slightly reduced by wearing an orthosis. However, a significant reduction of right pelvic obliquity was measured only with the bandage, with a mean angle of 1.3 degrees (±0.6 degrees).
During normal condition, pelvic obliquity angles for left and right were 7.5 degrees (±2.5 degrees) and 7.2 degrees (±2.3 degrees), respectively. Wearing an orthosis had a significant effect on the pelvic obliquity during latero-flexion, showing a significant increased pelvic obliquity when wearing an orthosis with regard to the unbraced condition. The bandage and spinal cast showed the largest increase in pelvic obliquity. Wearing the Jewett showed the least increase in pelvic obliquity (Figure 5).
Compared with the unbraced conditions, every volunteer experienced a limitation in movement when wearing an orthosis. However, limitations were not experienced in all tasks with the bandage, and when limitations were experienced, they were very small. The largest obstruction in movements was reported for the Jewett brace and the spinal cast. Concerning comfort, the bandage scored the best, showing no difference with the unbraced condition. With regard to pain caused by the orthoses, the bandage scored best by causing no pain. The bandage was followed by the SecuTec Dorso and the spinal cast. The Jewett scored worst.
The spinal cast was scored as less hygienic compared with the other orthoses (Figure 6).
The purpose of this study was to evaluate and compare movement reduction and comfortability of four types of thoracolumbar orthoses compared with normal spinal motion using IMA and questionnaires.
As the results show, orthoses limit movements during daily activities as shown by decreased bending angles, reduced angular rates, differences in sway, and changes in pelvic movement.
This indicates that wearing an orthosis does influence the motion of the spinal segments in the thoracolumbar region. The most rigid orthoses provided the most movement restriction, but simultaneously scored worse in comfort.
We objectified differences between the orthoses. Jewett was most restrictive in the STS test, while SecuTec Dorso had the highest influence of movement during the block-step test. The spinal cast had the largest reduction in the flexion test; however, it also showed the least reduction in backward bending.
Overall, the spinal cast seemed to be the most rigid but least comfortable, while the bandage was in all tasks the least restrictive, but most comfortable.
Pelvic obliquity seemed to be an interesting parameter. During braced conditions, in some tasks it decreased, while in other tasks it increased. In daily tasks such as stair climbing (block-step test) and getting up from a chair (STS test), pelvic obliquity decreased when wearing a brace, probably as a result of total movement restriction. However, in the latero-flexion test, where volunteers were encouraged to move as far as possible, pelvic obliquity increased compared with the unbraced condition.
A systematic review by van Poppel et al.12 in 1994 showed that there is evidence that lumbar supports reduce trunk motion for flexion-extension and lateral bending. These findings are consistent with the findings of this study, but in addition, this study showed that the decrease of motion in the spinal segments is compensated by increased movement of the sacroiliac joints and pelvis, as measured by an increase of pelvic obliquity.
Because of the compensatory increase in sacroiliac, pelvic, and hip movements, these joints should be clinically investigated in patients with lower-back pathologies. Pain or stiffness in the sacroiliac or hip joints could be a relative contraindication for a thoracolumbar orthosis.
The bending angle, mainly forward bending, is the most restricted movement, as shown in the flexion-extension test. This restriction is caused not only by mechanical impairment due to the rigidity of the orthoses, but also by the lumbar lordosis achieved by the orthoses.
Barring the reduction of the bending angle, the bending angular rate was also reduced. So, while wearing a brace, not only were absolute movement restrictions measured, but also the peak velocities decreased. During STS or block-step test, these impairments were compensated by an increased sway, either in forward or lateral direction.
This was shown by the smaller range of motion during sitting down that was compensated by an increase in start-sway (Jewett). Also during rising from a chair, the bending angle and bending angular rate were decreased, but start-sway was increased (all braces, but most with spinal cast). These objective results are comparable to the questionnaire, which indicates that the Jewett and the spinal cast provide more impairment in the bending angle than the other orthoses.
Also in the other tasks, the objective outcomes provided by the sensor measurements are comparable to results provided by the questionnaire, wherein the more rigid orthoses (spinal cast, Jewett) provided more movement restriction. However, they also scored worse in comfort.
All braces except the bandage were evaluated as less comfortable compared with the unbraced condition. Especially, the Jewett and the spinal cast were observed to be the least comfortable orthoses. The Jewett scored worst as it is pinching, not easy to wear under clothes, and interferes with breathing; however, the spinal cast scored as the least hygienic.
However, comfort reported by able-bodied subjects may be different compared with patients with spinal disorders. Able-bodied subjects only experience the negative issues of the spinal braces, while for patients with spinal disorders experiencing pain and other complaints, braces do have a certain goal of achieving pain control by movement restriction. Furthermore, in this study, there was only one size of each orthosis available for all subjects. Therefore, optimal fit was not always achieved, which may have caused additional discomfort.
Moreover, the questionnaire is not validated, and the clinical relevance of the questions can be discussed. However, we used the questionnaire to obtain information about the comfort of the braces, and as far as we know, no validated questionnaire is available to analyze this.
A recent study of Morrisette et al.13 comparing inextensible (e.g., spinal cast) with extensible (e.g., bandage) lumbar spine orthoses in patients with low back pain showed better subjective results for the inextensible orthosis. Thus, despite increased stiffness and motion restriction of the inextensible orthoses, patients with low back pain experienced these orthoses as more effective and comfortable compared with the extensible orthosis.
The sensor positioning is important to mention. Before the study was started, the position of the sensor was extensively discussed regarding how to achieve the best results. It could not be placed on the lumbar spine itself because of the orthoses. A few options were discussed (e.g., above the orthosis, the sternum, and the sacrum). The sacrum was chosen because it can be easily identified in every patient, and moreover, the sacrum is the connection between the spinal column and pelvis. Spinal and pelvic movements are very much related to each other; restriction in pelvic movement results in compensatory increase of motion in the lumbar spine and vice versa. Therefore, measuring sacral movement gives a good impression of the motion of the spine.
As discussed in the introduction, because of the lack of evidence, the choice for one specific brace is often made according to the preference of the hospital or surgeon. With the worldwide increase in health costs, the choice is probably also dependent on price. The bandage is the cheapest orthosis (€62.00), subsequently followed by the spinal cast (€236), the Jewett (€354.24), and the SecuTec Dorso (€605.84). However, with regards to hygienic aspects, a spinal cast cannot be cleaned, so in many cases after 8 to 12 weeks, a new cast has to be made, doubling the cost.
In conclusion, all orthoses influence spinal movement during several daily tasks such as rising from a chair, climbing stairs, and bending forward and backward, as was shown by IMA. There are differences in the braces regarding the degree of motion reduction, comfort, and costs. Therefore, it is important to treat patients with spinal problems as individuals and for some indications more or less rigidity is needed to achieve the desired immobilization.
RECOMMENDATIONS FOR CLINICAL PRACTICE
Although in this study, we performed analysis on healthy individuals, we tried to translate the data to recommendations for clinical practice. The spinal cast seems to be the most suitable in conservative treatment of thoracolumbar fractures in young, active patients because it is the most rigid orthosis with the highest movement restrictions, and thus seems to achieve the best prevention of posttraumatic kyphosis. The elderly patient with an (osteoporotic) thoracolumbar fracture could best be treated with a SecuTec Dorso because it is easier to use and more comfortable. The bandage is useful in chronic aspecific low back pain where movement restriction is not really necessary. Attention should be paid to the compensatory pelvic movement; spinal orthoses are relatively contraindicated in patients with sacroiliac or hip pathologies.
Further research on patients with spinal disorders should be performed to confirm these statements.
The authors are grateful to our orthotist and plaster technician Ton Olzheim and his colleagues for their technical input and practical assistance in this study. The authors also thank Bauerfeind for supplying the SecuTec Dorso and Spronken for supplying the bandage and Jewett brace.