| BackgroundThe injury of backbone and spinal cord are very common in clinics these days, which can cause severe disabilities and mortalities in SCI patients. Cervical SCI often cause quadriplegia, while thoracic and lumbar SCI can lead to paraplegia. Although physicians have tried hard to solve this problem for many years, there is still not a single exact method for about how to fully repair and regenerate the injured nerves of spinal cord nowadays.From the 60-70s in the last century, foreign scientists had taken great efforts in developing a special assistant instrument in order to help the paraplegia stand and walk which was call an orthosis for ambulation(Reciprocating Gait Orthosis, RGO). In 1973, Pro. Douglas of Louisiana State University in America invented a sort of orthosis which could help the paraplegia to stand and their lower limb to reciprocate forwards. It was called an RGO (Reciprocating Gait Orthosis). The initial design of RGO was composed of a double of Hip Knee Ankle Foot Orthosis (HKAFO) and a hard pelvic girdle. Its double hip hinges could only achieve the function of flexion and extension which were connected by two traction ropes packaged by drive pipes. Its upper limb of chest request was located at the underneath of Breastbone sword suddenly. When patients held their double turns or mobility aids to move their trunk forwards at standing phase, one side of RGO's hip joint would extend backwards in order to make the other side flexure through their traction ropes. By this mean, the paraplegia could move forward.In 1987, Steeper Company of UK developed RGO to an advanced type by great efforts on the basis of RGO, which was called ARGO (Advanced Reciprocating Gait Orthosis). The characteristic of ARGO is that there is only one traction rope packaged by drive pipe which connects two sides of hip hinges. It could control its flexion and extension of hip joints alternately, so as to reduce the friction resistance. At present, there are three to four walking orthoses that have been used clinically undergone thirty to fourty years. However, RGO had undergone a slow development and promotion because of its lately starting to use in China. The reason why it had been used lately and slowly should be mainly due to its high price and their uncomprehensive systematic rehabilitation programme. Many patients couldn't acquire its full use although they had been fitted up with a set of RGO before.Because of the above reasons, our hospital has explored out self-manufactured domestic RGO based on the bodily form of native people and paraplegic's real acquisition. Until now, there aren't any tests and reports correlated with its biomechanical tests in China. So we bought the European biomechanical test standard of prostheses and orthoses-《External limb prostheses and external orthoses -Requirements and test methods》. After it had been translated into Chinese, we found that it is still not very comprehensive about the tests of RGO's each component in this standard. In clinics, we want to explore out the standardized rehabilitation training programme continuously for complete SCI patients. At the same time, we also hope to conduct quantification analysis about these patients' ambulation through more precise and objective methods. Thus, our research is aimed to explore the biomechanical characteristics of correlative discreteness of RGO and its theraputic effect in clinical application; we also conducted 3-D gait analysis for paraplegic patients to explore the gait model of paraplegic patients who wear RGO while walking to ensure the clinical capability and applying foreground of RGO.Materials and Methods1 We used S-type tensile force transducer to test the tensile force on the posterior wireropes of RGO that produced by 18 complete spinal cord injured patients when they were walking with the aid of RGO, and measured their ranges of hip joint motion by a joint goniometer. Then we took their average as a reference value. We set up MTS(Material test system 858) machine in our laboratory according to the reference value in order to carry out fatigue experiment on the posterior wireropes of 18 RGO samples. Finally, we took the acquired data into statistical analyze. We adopted pertinence analysis two group variables to analyze the spearman correlation cofficient between their bodymass and tensile forces, and regard "P<0.05" as significant difference. If it shows significant correlation, we will divide the tensile forces into several groups by bodymass, and then calculate their mean values in each group. We also calculated their mean hip range of motion(degree) and the fatigue circulation and their ranges of upper and lower values in each group. Finally, we used statistical methods of One-Way ANOVA and LSD to compare the data in three groups, and regard "P≤0.05" as significant difference.2 We chose eighteen paraplegic patients with complete spinal cord injury of lesion level between C6 and T12 who had been fitted up with RGO in the Work Injury Rehabilitation Center of GuangDong Province as clinical test objects. Exercises such as ranges of joint motion, strength training, transferring and balance items were conducted and followed by walking exercises with the aid of reciprocating gait orthosis (RGO). After they have undergone the above walking exercises for 3 months, we examined their ambulation capacity(such as average step length, walking distance in 6 minutes and ambulation time for 10 meters). We also determined the nature of our examination by evaluating their ambulation function of all these patients.3 Sixteen paraplegic patients with complete spinal cord injury of lesion level between T4 and T12 who had been fixed up with RGO in the Work Injury Rehabilitation Center of GuangDong Province were chosen as clinical test objects. Comprehensive rehabilitation training and walking exercises with the aid of RGO are the same as "Materials and Methods 2". We used the Modified Barthel Index and Functional Independence Measure Scale to examine their ADL (activity of daily living) of these 16 patients before and after being fixed up with RGO 3 months. All data were analysed by SPSS 12.0 statistical software, two-detailed T test was used to examine the differences between these two groups. We regard "P≤0.05" as a remarkable difference.4 We chose twelve paraplegic patients with complete spinal cord injury of lesion level between T4 and T12 who had been fixed up with RGO in the Work Injury Rehabilitation Center of GuangDong Province as clinical test objects. Comprehensive rehabilitation training and walking exercises with the aid of RGO are the same as "Materials and Methods Two". We conducted cold water experiment and urine germiculture before and after being fixed up with RGO 3 months respectively, and we also examined their bladder volumn, remaining volumn, mean pressure of bladder and rectum, et al. All data were analysed by SPSS 12.0 statistical software, and two-detailed T test was used to examine the differences between these two groups. We regard "P≤0.05" as having remarkable difference.5 Ten paraplegic patients with complete spinal cord injury of lesion level between T4 and T12 were selected into our study who had experienced RGO gait training for at least 3 months. We used 3-D gait analysis system of Vicon Nexus 1.2 in the rehabilitation department of Sun Yat-Sen Hospital to test these subjects and analyze the following data. We have examined such parameters as gait speeds, candences, stride lengths, pelvic angles of rotation, hip ranges of motion, crutch forces, angular velocities of hip flexion and extension phases, et al. We used Spearman rank correlation coefficient to analyse the relationship between the level of spinal cord injury and their kinematic and kinetic values, and we regard "P≤0.05" as a remarkable correlation.6 All data are expressed by (?)±s, and their outcomes were analyzed by SPSS 12.0 statistical software.Results1 The tensile force of complete spinal cord injury patients with lesion level between T4 and T12 on the posterior wirerope of RGO were increasing by degrees along with the increase of body mass. There was a positive correlation between tensile force and body mass. Their range of hip joint motion was 19.56±1.69°. The average values of RGO's fatigue circulation of three groups were 95450±2636, 127171±27194 and 204620±7148 times respectively, and their ranges of upper and lower values were 92684<μ<98216, 100756<μ<153586 and 196405<μ<212835 separately. There was statistical differences among each group (F=54.331, P<0.001).2 The average step length, walking distance in 6 minutes and ambulation time for 10 meters of all patients were 44.24±5.13 cm, 76.36±10.27 m and 32.75±9.36 s respectively. In these eighteen paraplegic patients with complete spinal cord injury, ten cases had achieved household functional ambulation, four of which had achieved community functional ambulation. The other eight patients had achieved therapeutic ambulation.3 Before and after being fixed up with RGO 3 months, their MBI scores of these sixteen paraplegic patients were 29.98±3.95 and 61.00±5.85 points, and FIM scores 51.06±3.53 and 78.69±3.40 points respectively. There were significant differences between these data (P<0.001). There were ten cases who had achieved functional ambulation, and six had achieved therapeutic ambulation.4 Cold water experiments were all positive in these paraplegic patients. Eleven cases showed positive character in urine germiculture before being fixed up with RGO, and only four positive after being fixed three months later. Their mean bladder volumn and pressure of bowel (368.42±28.50 ml, 44.57±4.94 cmH2O) were significantly enhanced (200.17±19.30 ml, 25.91±4.80 cmH2O) (P<0.001), while remaining volumn and filling pressure of bladder (41.42±7.39 ml, 26.07±3.67 cmH2O) significantly reduced (144.92±44.24 ml, 46.95±5.39 cmH2O) (P<0.001).5 The mean candence and stride length of these ten subjects were 37.4±2.15 step/min and 91.6±9.09 cm. Their mean hip range of motion, angular velocities of hip flexion and extension phases were 42.57±5.43°, 22.34±1.96°/s and 124.75±9.31°/s respectively. The gait speed(rs=0.914, P<0.001), stride length (rs=0.926, P<0.001), peak crutch force(rs=-0.693, P=0.026), pelvic rotation angle (rs= -0.926, P<0.001), hip ROM (rs=0.963, P<0.001), mean crutch force (rs=-0.877, P=0.001) and angular velocity of hip extension phase (rs=0.742, P=0.014) of SCI patients all had significant pertinences with their spinal cord injury level.Discussion1 Along with the development of modern biomechanics and rehabilitation medicine, the manufacture and assemblage of RGO have achieved prodigious progress. The application of RGO can help the paraplegics acquire the ability to stand and walk again, to boost their self-confidence and return to society at an early date. We found that the component of RGO which first ruptured is its posterior wirerope fixed screw according to the outcome of biomechanical test. Therefore, we consider posterior wirerope fixed screw of domestic RGO as its weak point. On the other hand, statistic analysis shows that there is a positive beeline correlation between SCI patients' body mass and spinal cord injury level. Thus, the tensile force of complete spinal cord injury patients with lesion level between T4-T12 on the posterior wirerope of RGO will increase by degrees along with the increase of body mass. Accordingly, danger will also increase with the enhancement of their body mass. So, we recommend SCI patients of different body mass (<55 kg, 55-70 kg and >70 kg) replace their posterior wirerope fixed screws after achieving stated steps (196405, 100756 and 92684 paces) respectively.2 RGO can help complete SCI patients to achieve practical ambulation. The trait of RGO is its rapidness of walking speed, lower energy cost and safety for which it may be accepted by SCI patients. RGO not only provides the paraplegics with its effectiveness of support and aid action, but also make them move by their remaining function of trunk and upper limbs. Walking with the aid of RGO can help the paraplegics prevent muscle atrophy and osteoporosis effectively, improve the function of urinary bladder and bowel, prevent press tumefaction and deep vein thrombosis, boost up pulmonary and cardiovascular function; it can also administer to patients' psychological health and conduce them to participate in social life successfully. When we judge whether a patient can use a set of RGO, the level of spinal cord injury, stability of backbone and his physically or mentally wellbeing are all the factors that should be taken into consideration. In general, SCI patients except cervical spinal cord injury can all use a set of RGO to stand and walk. And the lower the injury level, the better its effect. The stability of vertebral column is the key of using RGO, and the level of spinal cord injury is the determinant factor if a patient could use it safely.3 Their comeback of activity of daily living and ambulation in SCI patients still has a close relationship to their bodily form, spinal cord reflection, control of vertebral column and balance ability, etc. Appropriate bodily form is propitious to the transfer of SCI patients, and measurable tension reflection can enhance their lower blood pressure due to body location and reinforce their stability of vertebral column and repertory capacity of pulmonary and cardiovascular. Therefore, the influencing factors that affect SCI patients of their ADL ability are omnifarious. It not only lies on the level of spinal core injury, but also on the intervention time of rehabilitation therapy, training technique and patients' psychological state closely. We should conduct pertinent rehabilitative training programme on the basis of each patient's idiographic condition and pay attention to their psychological rehabilitation. In a word, mastery of correct adaptable evidences and comprehensive rehabilitation are the premiss of using RGO successfully.4 Clinical practice also indicates that, RGO could effectively improve SCI patients' function of bladder and rectum. It can make them participate in social life and achieve the goal of equal communion with others and re-entry society. From laying up all day to standing and walking, paraplegic patients could not only prevent the calculus' coming into being and recrudescence in urinary system, reduce the infectious rate of urinary system so as to work up to balancing bladder, but accelerate the peristalsis of intestines and excretory function of rectum. So wearing RGO for paraplegic patients to be trained is also a stimulative process of enhancing the function of bladder and rectum. The improvement of the functions of bladder and rectum in paraplegia patients can prompt themselves to insist on ambulation training, thus form a good circulation. We found that RGO along with systematic rehabilitative therapy can not only increase bladder volumn and reduce remnant urine volume and infectious rate of urinary system availably; but also heighten mean rectum pressure, so it is also a better instrument for the recovery of rectum function. Thus it can be seen that, the successful premiss of using RGO to improve SCI patients' functions of bladder and rectum are to master the right adaptable evidences, to take patients' idiographic condition into consideration seriously and to put comprehensive rehabilitation measures into practice. In addition, most patients involved in our study can put on or take off their RGO by themselves, and can stand and walk wearing a set of RGO. They seldom feel discomfort within routine training periods and intensity, and their ability of ADL have achieved self-care level. This indicated that RGO can not only improve SCI patients' functions of bladder and rectum, but also enhance their ambulation function and quality of life.5 Our research has shown that, there is a remarkable correlation between their SCI level of complete SCI patients and the pattern of RGO gait. Their injury levels of SCI patients in our study vary from T4 to T12. This range of spinal cord section includes several nerve anatomic planes which predominate trunk muscle clusters such as spinal cord planes of predominating abdominal muscle clusters and iliopsoas. These nerve sections are in good condition in lower injured levels below T12 spinal cord sections, but damaged in thoracic SCI levels. Former researches have found that, the reserved function of trunk and lower limb in complete SCI patients mostly lies on their injured level. According to the outcome of our study, when complete SCI patients are walking with the aid of RGO, it shows negative correlation between their pelvic rotation angles and injured level, but positive in the range of motion about their hip joints. By this token, while complete SCI patients are walking with RGO, their nature of stability and harmony will descend gradually with the hoist of SCI level; but their energy cost will ascend accordingly. We make use of RGO's leverage of its hip joint linkage implement to help patients walk ahead alternately. When they walk along, their body mass centers firstly lean and transfer to one side of lower limb, then they may drive the other side of lower limb to move forward by dint of locomotion potential energy. Hence, it is crucial important for complete SCI patients to promote hip joint movement by the aid of trunk muscle clusters and both upper limbs' support. The mechanical characteristics of RGO gait can also explain our experimental results commendably.6 Literatures from overseas have reported that energy cost is also a reference guide line of gait analysis which is denoted by OC (Oxygen Cost). The lower the OC, the more abstemious the energy cost in ambulation. The symbol of natural gait is a kind of walk fashion which may cost the lowest energy expenditure. Kawashima used Vicon three dimensional gait analysis system to test the kinematic,dynamic and OC of ten SCI patients with the lesion level of different spinal cord sections. He considered that the physiological intensity of SCI patients' gait mainly rests with their SCI level. Phillips has reported that the sub-target heart rates, respiratory quotients, ventilatory volume per minute and oxygenic intake of SCI patients had all reduced by various degrees. He advised SCI patients to take in some special rehabilitation methods in order to enhance thieir cardiorespiratory function. Although we couldn't use OC analysis technique to examine the energy cost of these SCI patients because of the restriction of technical and facility condition, OC analysis will nevertheless become one of the most valuable guide lines of gait analysis in the future. Presently, our study involves kinematic and dynamic test of gait analysis, but still remains insufficiency relative to Kawashima's research. On the whole, these deficiency include exploration about OC and cardiorespiratory function test, which are the most necessary continous work for us to investigate on.Conclusion1 The posterior wirerope fixing screw of domestic RGO is its weak point, and the danger of rupture will increase by degrees along with the increase of SCI patients' body mass;2 SCI patients of different body mass (<55 kg, 55-70 kg and >70 kg) should replace their posterior wirerope fixing screws of RGO after achieving stated paces respectively;3 With the aid of RGO, patients suffered from complete spinal cord injury can restore standing and walking. RGO can also help paraplegic patients with complete lesion level between T4 and T12 to enhance bladder and rectum function, to prevent paraplegic complications and to improve their quality of life; SCI level is the key factor for patients that determines whether they can use a set of RGO or not, systematic rehabilitation and patients' single differenciation are the important factors that affect SCI patients of their usage outcome;4 The abnormal movement of pelvic, limitation of hip range of motion and excess upper limb load are the main reason that lead to ambulatory disorders in higher thoracic lesion of complete SCI patients;5 Higher thoracic SCI patients should be undertaken some rehabilitative training exercises to reduce excessive physiological load, and thus help to improve their acquired ambulatory capacity.
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