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Comparison of Static Balance, Walking Velocity, and Energy Consumption with Knee-Ankle-Foot Orthosis, Walkabout Orthosis, and Reciprocating Gait Orthosis in Thoracic-Level Paraplegic Patients

Kaoru Abe, MS, CPO

ABSTRACT

Orthoses are used by thoracic-level paraplegic patients in rehabilitation treatment. It is often difficult to choose the most suitable orthosis for each patient because previous studies have not focused on several measurements of the same patient with various types of orthoses. In this study, two thoracic-level paraplegic patients are compared for static balance, walking velocity, and energy consumption when fitted with three types of orthoses: knee-ankle-foot orthosis (KAFO), Walkabout orthosis (WO), and reciprocating gait orthosis (RGO). The RGO proved to be superior, reflecting results from previous studies. (J Prosthet Orthot. 2006;18:87–91.)

Standing and walking are important for treatment, physical function, and the psychological condition of paraplegic patients. In rehabilitation treatment, standing up is effective against muscular atrophy in particular. The ability to walk contributes to quality of life and convalescence. However, it is difficult for patients to stand and walk without a device for assistance, such as an orthosis. Accordingly, specialists should know which orthotic function is optimum for the patients. In medical rehabilitation and daily activity, a simple and effective orthosis is the most suitable.

Traditionally, hip-knee-ankle-foot orthoses (HKAFOs) have been prescribed for thoracic-level paraplegic patients. Recently a new HKAFO, the Walkabout orthosis (WO), became available. The WO is an orthotic component that connects the medial side between the knee-ankle-foot orthoses (KAFOs) and does not have thoracolumbar corsets.

Several articles have studied postural control as a function of standing and energy expenditure as a function of walking in paraplegic patients with an orthosis. Baardman et al. 1 compared the standing performance of an advanced reciprocating gait orthosis (ARGO) and an ARGO from which the Bowden cable was removed in paraplegic patients. Six male subjects with spinal cord injury (SCI) at T4 to T12 level participated in the study. Standing balance as the ability to handle balance disturbances (standing stability) and the performance of a functional hand task during standing were assessed in both orthoses under varying conditions. No significant differences with respect to standing performance were found in the two orthotic configurations. However, the results indicated that the crutch force needed for maintaining balance during various tasks may be much higher in the orthosis without the Bowden cable. Accordingly, the reciprocal hip joint link in the ARGO seemed to substantially decrease the effort of standing for the upper body.

Middleton et al. 2 investigated the effect of medially linking (by Walkabout) KAFOs on postural stability and sway during quiet standing and functional activities for persons with SCI (9 men with T5 to T12 paraplegia). The main outcome of measurement was a mean amplitude of sway and sway path in anteroposterior and mediolateral directions, derived from center of pressure (COP) measurements on a force platform. Significant differences were found between linked and unlinked KAFOs; side-to-side mean amplitude of sway was less and sway path was greater for SCI subjects when they wore the linked KAFOs. The author concluded that medial linkage of bilateral KAFOs provides an effective strategy for improving stability and increasing posture control.

Harvey et al. 3 compared energy expenditure and measurements during walking using the WO and the isocentric reciprocal gait orthosis (IRGO) in 10 individuals with complete T9-12 paraplegia. The subjects were measured for energy expenditure during walking using each orthosis with elbow crutches at a self-selected pace over three different terrains. Data collected included expired ventilation, heart rate, speed of walking, oxygen uptake, oxygen cost, and physical cost index (PCI). Subjects walked significantly more slowly with the WO than with the IRGO, despite no marked differences in either heart rate or oxygen consumption. However, the oxygen cost and the PCI of gait were significantly greater using the WO than with use of the IRGO. The study showed that the metabolic demand of walking with the WO was greater than that of walking with the IRGO.

The objective of this study was to compare energy cost, walking velocity, and static balance with KAFOs, WO, and RGO in two paraplegic patients. Previous studies revealed little about these three measurements with the same patients using the three types of orthoses. Accordingly, this study was designed to prove a hypothesis derived from the previous studies in which the RGO is superior for paraplegic patients.

PATIENTS AND METHODS

PATIENTS

Two paraplegic patients participated in this study. Patient 1 was a 66-year-old woman with impairment caused by an intramedullary tumor. Her spinal cord functional level was T12 incomplete paraplegia, and her American Spinal Injury Association (ASIA) impairment scale4 was grade C. Total rehabilitation programs were conducted in 180 days. Patient 2 was a 33-year-old man with impairment caused by a traffic injury. Spinal cord functional level was T9 incomplete paraplegia, and his ASIA impairment scale was grade C. Total rehabilitation programs were conducted in 167 days. The subjects were trained by physical therapists in push-up exercise, standing and walking in a parallel bar, and orthotic walking with a quadruped walker cane. Each patient was fitted with a KAFO, WO, or RGO for three walking exercises.

ORTHOSES

The KAFOs consisted of uprights, straps, and shoe orthoses as in a conventional long leg brace (LLB). Double Klenzak ankle joints and dial lock knee joints were used for adjusting each joint angle. The RGO and WO ( Figure 1 ) were assembled using the KAFOs. The RGO combined the thoracolumbar corsets and Bowden cable unit and the KAFOs ( Figure 2 ), and the WO connected the medial side between both KAFOs ( Figure 3 ).

Although customizing the RGO presented no difficulty, remodeling the WO created problems. There was a possibility of breakage at the part between the upright and the Walkabout unit because of configuration of both components. A custom base plate of iron ( Figure 4 ) was made for reinforcement. It was fixed with screws (diameter of 6 mm) to the uprights, and the original Walkabout unit was connected with the usual approach ( Figure 3 and Figure 5 ).

MEASUREMENT

The measurements were performed as the final evaluation of the rehabilitation program, and informed consent was obtained from the patients before participating. Staff members attended the patients to prevent falls or other mishaps during each measurement. In separate walking tasks, the patients were fitted with the KAFO, the WO or the RGO; they then walked on level ground at a self-selected pace. The data on static balance ability, velocity, and energy consumption in walking are presented.

STATIC BALANCE

The total path length of COP (cm) 5 and the area of an ellipse for rejection (AER; cm2) 6 were calculated from the signal of a strain sensor of two force platforms (20 x 40 cm) by personal computer. The data of both measurements represented static balance capability, which depended on the kind of orthosis. The total path length of COP represented the body sway, and AER showed extent of the anteroposterior and lateral directions. The patients stood on the force platforms with their hands on their waists. After 30 seconds of acclimation, data were recorded for 20 seconds.

WALKING VELOCITY

Walking velocity (m/min) was measured three times along a length of 10 meters, with an allocated walk distance of 5 meters front and back (total length was 20 meters).

ENERGY CONSUMPTION

An energy consumption measurement was performed to determine how much oxygen it took for patients to walk with each orthosis. This study adopted oxygen cost as one of the values representing energy consumption. The oxygen rate (mL/kg/min) reflects the level of exercise intensity, although oxygen cost, which describes the amount of energy required to perform a given task, was normalized for body weight and distance traveled. 7 Body weight did not include the weight of the orthoses and aids. The patients were tested with a Cosmed K2 portable telemetry system, 8 which was worn on their chest and measured the concentration and volume of gases expired through a tight-fitting face mask, 3 and orthotic walking with quadruped walker cane ( Figure 6 ).

STATISTICAL ANALYSIS

A Friedman's chi-squared r-test and Wilcoxon t-test with Bonferroni correction were used for statistical analysis.

RESULTS

Significant differences (p < 0.05) in static balance were found in KAFO versus WO, and KAFO versus RGO, on the average total path length of COP. Average AER had significant differences (p < 0.05) among all orthoses ( Table 1 and Table 2 ). Significant differences (p < 0.05) were also found for walking velocity and energy consumption for KAFO versus WO, KAFO versus RGO, and WO versus RGO ( Table 1 and Table 2 ).

DISCUSSION

Harvey et al. 9 discussed functional outcomes in paraplegia with the WO and the IRGO. Most subjects had difficulty maintaining hip joints in a locked position because the IRGO restricted the hip joints and lumbar hypertension required to position the ground reaction forces posterior to the hip joint. The author explained that SCI individuals were totally unable to maintain balance without the WO linkage (only KAFOs) compared with WO linkage of KAFOs.

Baardman et al. 1 compared ARGO with an ARGO in which the Bowden cable was removed for standing stability. Insignificant differences with respect to standing performance were found for the two orthotic configurations. Therefore, static stability was maintained not because of the Bowden cable of the RGO but because of the pelvic girdle. Middleton et al. 2 commented that paraplegics could maintain standing balance while wearing unlinked KAFOs (without Walkabout unit) by using a noticeable "C" posture with hip joint hyperextension.

In this study, the subjects had significantly superior balance maintenance capability when using the RGO than when using the WO or KAFO. This superior capability may be attributed to the stability of anteroposterior and lateral directions in pelvis and hip joints. Maintenance of paraplegic standing depends on the iliofemoral ligament with hyperextension in the hip joint. A pelvis and hip joint motion during static erection is limited in all directions, especially laterally, when the subject is wearing an RGO, due to the pelvic girdle or corset that connects the KAFOs. The WO produces fixed abduction and adduction of hip joints, whereas it allows some flexion and extension; that is, stability is less than that of an RGO in the pelvis and hip joints. The KAFOs are at a disadvantage in terms of stability for paraplegic standing because they do not influence hip joint motion. This study's findings of balance maintenance agreed with previous results. 1,2

The walking velocity experiments using a WO showed the same approximate values as those of previous studies,3 but subjects had significantly faster walking velocities when wearing an RGO than when wearing a WO or KAFO. This result also agreed with the previous studies. 3,9,10

The Walkabout unit, by adding a hinge that joins the legs proximally in an axis not aligned with the hip joints, reduces some freedom of movement in the lower body. 2 The RGO assists hip flexion while the WO does not, and the RGO's hip, pelvis, and lumbar supports assist balance during strides. 9,11

The data for energy consumption agreed with the findings of previous studies. 3,10,12 RGO may be superior in oxygen cost because of improved hip flexion movement. The WO and the KAFO had different results because they depend mainly on the swing motion of lower extremities, and they lack a supporting mechanism like that of the RGO. Furthermore, this result may reflect differences of equipment, subjects, and methods of assessment among the various studies. 9

CONCLUSION

Investigators disagree about the aim of orthosis use by paraplegic patients in daily activities. Several have reported that the ease of donning and doffing is most important, whereas others have suggested that orthotic function is more significant. The best orthosis for a patient has a simple construction and includes function assistance that conforms to the degree of disorder.

In this study, the differences in static balance, walking velocity, and energy consumption in paraplegic patients with KAFO, WO, and RGO were compared. The investigation showed RGO was superior, in approximate agreement with previous studies, although only two examples are given. To advance substantially in our understanding of the role of orthoses for paraplegic patients, we will need more subjects and long-term study.

ACKNOWLEDGMENTS

The author thanks Prof. Dr. Akira Miyamoto of the Graduate School of Social and Cultural Studies, Nihon University, and Mr. Peter Piro.

Correspondence to: Kaoru Abe, MS, CPO, 203-1-303 Kumagawa, Fussa, Tokyo 197-0003, Japan; e-mail: .


KAORU ABE, MS, CPO, is a student of the Graduate School of Social and Cultural Studies, Nihon University, Saitama, Japan.

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