Surgical repair of a large intrathoracic meningocele associated with neurofibromatosis type 1 after failed cystoperitoneal shunts: illustrative case.

BACKGROUND: Surgical treatment of intrathoracic meningoceles, commonly associated with neurofibromatosis type 1 (NF1), aims to reduce sac size for symptomatic relief. The procedures can be divided into cerebrospinal fluid diversion and definitive repair. The authors describe the management of an intrathoracic meningocele in a 56-year-old female with preexisting NF1. OBSERVATIONS: The patient presented with progressive dyspnea. Magnetic resonance imaging revealed a left hemithoracic meningocele arising from the thecal sac at C7-T2. Two attempts at diversion by cystoperitoneal shunts resulted in recurrence. For definitive repair, T2-3 costotransversectomy was performed, and intradural closure of the meningocele opening was performed utilizing spinal dura and autologous fascia lata graft. Trapezius muscle regional flap was turned for reinforcement. Persistent leak warranted reoperation 7 days later. A transthoracic approach was undertaken using video-assisted thoracoscopic resection of the sac at aortic arch level, with reinforcement by latissimus dorsi flap and synthetic materials. Mechanical pleurodesis was performed. Intradural repair of the meningocele opening was revised. LESSONS: Inherent dural abnormality makes repair difficult for meningoceles associated with NF1. A combined intradural and thoracoscopic approach with regional muscle flap and synthetic material reinforcement is a unique method for definitive treatment. Some essential points of perioperative management are highlighted.

Phase I-II Clinical Trial Assessing Safety and Efficacy of Umbilical Cord Blood Mononuclear Cell Transplant Therapy of Chronic Complete Spinal Cord Injury.

Umbilical cord blood-derived mononuclear cell (UCB-MNC) transplants improve recovery in animal spinal cord injury (SCI) models. We transplanted UCB-MNCs into 28 patients with chronic complete SCI in Hong Kong (HK) and Kunming (KM). Stemcyte Inc. donated UCB-MNCs isolated from human leukocyte antigen (HLA ≥4:6)-matched UCB units. In HK, four patients received four 4-µl injections (1.6 million cells) into dorsal entry zones above and below the injury site, and another four received 8-µl injections (3.2 million cells). The eight patients were an average of 13 years after C5-T10 SCI. Magnetic resonance diffusion tensor imaging of five patients showed white matter gaps at the injury site before treatment. Two patients had fiber bundles growing across the injury site by 12 months, and the rest had narrower white matter gaps. Motor, walking index of SCI (WISCI), and spinal cord independence measure (SCIM) scores did not change. In KM, five groups of four patients received four 4-µl (1.6 million cells), 8-µl (3.2 million cells), 16-µl injections (6.4 million cells), 6.4 million cells plus 30 mg/kg methylprednisolone (MP), or 6.4 million cells plus MP and a 6-week course of oral lithium carbonate (750 mg/day). KM patients averaged 7 years after C3-T11 SCI and received 3-6 months of intensive locomotor training. Before surgery, only two patients walked 10 m with assistance and did not need assistance for bladder or bowel management before surgery. The rest could not walk or do their bladder and bowel management without assistance. At about a year (41-87 weeks), WISCI and SCIM scores improved: 15/20 patients walked 10 m ( p = 0.001) and 12/20 did not need assistance for bladder management ( p = 0.001) or bowel management ( p = 0.002). Five patients converted from complete to incomplete (two sensory, three motor; p = 0.038) SCI. We conclude that UCB-MNC transplants and locomotor training improved WISCI and SCIM scores. We propose further clinical trials.

Efficacy of Postoperative Pain Management Using Continuous Local Anesthetic Infusion at the Iliac Crest Bone Graft Site in Patients with Adolescent Idiopathic Scoliosis: A Parallel, Double-Blinded, Randomized Controlled Pilot Trial.

Study Design Randomized controlled trial. Objective Adolescent idiopathic scoliosis (AIS) is a common spinal deformity that affects every population. In severe deformity, surgical intervention is performed. Autogenous iliac crest bone graft (ICBG) harvesting remains a common procedure worldwide for scoliosis surgery. Postoperative pain at the ICBG donor site is a major concern in patients undergoing spine surgery that affects postoperative functional outcome and consumes health care resources. Previous studies have noted a decrease in pain and postoperative analgesic use with the application of continuous infusion of anesthetic at the ICBG site in comparison with placebo. However, there is lack of evidence addressing the efficacy of continuous anesthetic infusion at the ICBG site in young patients and in particular those with spinal deformity, such as AIS. As such, this parallel, double-blinded, randomized controlled trial addressed the pain management efficacy of continuous anesthetic infusion versus saline at the ICBG site in patients with AIS during the immediate postoperative period. Methods Participants were randomized into two groups. Group A (control subjects) received 3 mL per hour of saline locally at the ICBG site, and group B (treatment subjects) received a constant rate of infusion of 3 mL per hour of 0.25% levobupivacaine. Both groups received their postoperative intervention for 47 hours. All subjects and outcome assessors were blinded to the type of intervention. Utilizing the visual analog pain scale, pain was assessed at the primary spine surgical site, ICBG site, and contralateral ICBG site. Overall physical pain was assessed by the McGill Pain Questionnaire. The degree of analgesic use and complications were also evaluated. All outcomes were assessed up until the fourth day of the patients' hospitalization following surgery. Results Twelve subjects were recruited (five in group A; seven in group B). No difference was noted at baseline regarding age, weight, height, arm span, sex, curve type, instrumented and fused levels, length of hospitalization, and pain scores between groups. Postoperatively, no difference was noted in surgical site pain between groups (p > 0.05). However, decreased ICBG and contralateral ICBG pain decreased twofold in group B patients in comparison with group A. Similarly, group B subjects had notably decreased postoperative overall pain scores (group A, mean 15.3; group B, mean 3.8). No significant differences were noted for the pain scores due to the small sample size. Conclusions This study is the first with a robust level I study design to assess the efficacy of continuous infusion of analgesia into the ICBG site in young patients with AIS. This pilot study noted a trend that continuous anesthetic infusion reduces pain at the ICBG site and may further decrease overall physical bodily pain. This study further established a sample size calculation to facilitate large-scale studies addressing these parameters. This study provides further support of postoperative pain management options for children with spinal deformities.

Disappearing bone disease of the humerus and the cervico-thoracic spine: a case report with 42-year follow-up.

BACKGROUND CONTEXT: Disappearing bone disease (DBD) is a rare idiopathic musculoskeletal disorder that is distinguished by bone resorption without bone formation, vascular or lymphatic vessel proliferation, and soft-tissue swelling. Long-term follow-up of a patient with DBD has rarely been reported in the literature. PURPOSE: The following is a case report of a female patient with DBD of the humerus and the spine who was followed for 42 years, documenting the progression of the disease and outcomes. STUDY DESIGN: Case report. METHODS: A review of the medical records since the time of initial hospital admission throughout follow-up was performed. RESULTS: A female patient was first seen at our institution at the age of 14. She later developed DBD of the humerus and the spine. The initial difficulty encountered was reaching the diagnosis, and later on with management of the patient as the disease progressed. The case was complicated by syrinx and arachnoid cyst formation, which caused neurologic changes leading to tetraplegia and shunt infection. The patient's inability to form a solid fusion mass led to repeated implant loosening and progressive deformity despite efforts made to stabilize both the humerus and the spine. The treatment modalities used were oral bisphosphonates, rhBMP, repeated surgeries, and instrumentation with adjunct bone graft and substitutes. At the age of 56 years, the patient died because of septicemia secondary to urinary tract infection from tetraplegia. CONCLUSIONS: To our knowledge, this is the first report documenting a 42-year follow-up of a patient with DBD of the humerus and the spine. Our report showed that DBD greatly affects the quality of life of the patient. Close follow-up, a multidisciplinary approach, and supportive care are stressed when managing patients with DBD.

A population-based cohort study of 394,401 children followed for 10 years exhibits sustained effectiveness of scoliosis screening.

BACKGROUND CONTEXT: The value of scoliosis screening has been recently shown in a multicenter randomized controlled trial. However, the long-term sustainability of the clinical effectiveness of scoliosis screening as a routine health service remains unknown. PURPOSE: The aim of this study was to assess the sustainability of the clinical effectiveness of school scoliosis screening. STUDY DESIGN/SETTING: A large population-based cohort study with a 10-year follow-up was conducted. PATIENT SAMPLE: A total of 394,401 students who were in the fifth grade during the five academic years from 1995/1996 to 1999/2000 formed five consecutive annual cohorts. The students were eligible for the Hong Kong scoliosis screening program, with their screening history and medical records until their nineteenth birthdays being assessed. OUTCOME MEASURES: The outcome measures considered in the study were development of adolescent idiopathic scoliosis by the 19 years of age and the Cobb angle. METHODS: The clinical effectiveness of scoliosis screening was assessed by referral rate for radiographic diagnosis, sensitivity, specificity, and predictive values. RESULTS: A total of 306,144 students (78%) participated in scoliosis screening, which used a two-tier system. The prevalence of curves of 20° or greater was 1.8% (95% confidence interval [CI], 1.7-1.8%), whereas the referral rate for radiography, the sensitivity, and the positive predictive value (PPV) for curves of 20° or greater were 4.1% (95% CI, 4.0-4.2%), 91% (95% CI, 90-92%), and 40% (95% CI, 39-41%), respectively. Across the five consecutive annual cohorts, the prevalence and sensitivity for curves of 20° or greater increased by 0.23% (95% CI, 0.21-0.25%; p<.001) and 0.76% (95% CI, 0.43-1.04%; p<.001) per year, respectively; however, the PPV was reduced by 1.71% (95% CI, 1.09-2.33%; p<.001) per year. CONCLUSIONS: This report describes the first large population-based study with a long-term follow-up indicating that a scoliosis screening program can have sustained clinical effectiveness in identifying patients with adolescent idiopathic scoliosis needing clinical observation. As the prevalence of adolescent idiopathic scoliosis increases, scoliosis screening should be continued as a routine health service in schools or by general practitioners if there is no scoliosis screening policy.

Acute spinal subdural hematoma complicating lumbar decompressive surgery.

STUDY DESIGN: A case report. OBJECTIVE: To report a rare case of acute spinal subdural hematoma (SSH) complicating lumbar spine surgery, its characteristic presenting symptoms, diagnostic imaging, possible cause, and pitfall in management. METHODS: A 59-year-old woman with lumbar spinal instability and stenosis underwent laminectomy and decompression at L3-L5 with instrumentation and fusion from L3-S1. RESULTS: Immediately following surgery, the patient presented with incapacitating pain of both lower extremities from the mid-thigh downward, which was not relieved by narcotic analgesia and was disproportional to surgical trauma. Left ankle and great toes weakness was detected at postoperative day 2 and deteriorated on day 6. Magnetic resonance imaging was performed urgently and revealed a characteristic SSH with thecal sac compression at the level of L2, proximal to the laminectomy. Emergency decompression and evacuation of the hematoma was performed. The patient had partial recovery 6 weeks postoperatively. CONCLUSION: Acute SSH is a rare complication of lumbar spine surgery. This diagnosis must be considered when severe leg pain, unresolved with analgesia and disproportional to surgical trauma, with neurological deterioration occurring after lumbar spine surgery. Magnetic resonance imaging is the imaging modality of choice to assist in the differential diagnosis of an SSH. Early surgical decompression is necessary for optimal neurological recovery.

The predictive value of the fulcrum bending radiograph in spontaneous apical vertebral derotation in adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective cohort study of Cobb angles (CA) and apical vertebral rotations (AVR) in 25 patients who had adolescent idiopathic scoliosis. OBJECTIVE: To assess in vivo the concomitant vertebral derotation occurring with correction of scoliosis deformity as a result of coupling effect by using the fulcrum bending radiograph and to assess whether the fulcrum bending radiograph can predict the amount of postoperative apical derotation when no additional intraoperative apical derotation maneuver is used. SUMMARY OF BACKGROUND DATA: Adolescent idiopathic scoliosis (AIS) is a 3-dimensional coupling deformity. Various studies have reported vertebral derotational effects, using different implant constructs and surgical techniques for AIS. However, none of them have considered the spontaneous coupling effect on vertebral derotation produced by correction of the coronal deformity, in particular, using the predictive capacity of the preoperative fulcrum bending radiograph. METHOD: Twenty-five patients with flexible Lenke type 1 AIS with CA greater than 45° who underwent posterior spinal fusion with instrumentation, without direct apical derotation were prospectively assessed. CA and AVR in standing, supine, and fulcrum bending positions preoperatively and in supine position postoperatively were assessed on radiographs and computed tomographic scans. RESULTS.: The study entailed 80% adolescent girls and 20% adolescent boys (mean age, 15.5 years). The mean AVR values on preoperative standing, supine, and fulcrum bending positions and postoperation were 24.2°, 17.7°, 9.8°, and 8.1° respectively. The preoperative AVR highly correlated with the preoperative CA (R = 0.75). The postoperative AVR was correlated with the postoperative CA (r = 0.82) and the change in curve magnitude (r = -0.49), correction rate (r = -0.83), and fulcrum bending correction index (r = -0.45) (P < 0.05). There was no significant difference in AVR between preoperative fulcrum bending and postoperative assessment. CONCLUSION: Correction of scoliosis deformity produces spontaneous reduction of rotational deformity through coupling. The amount of spontaneous apical vertebral derotation with fulcrum bending can be used to assess the flexibility of the rotational deformity. In flexible curves, it also predicts the amount of apical derotation achievable with surgery. These should be considered when assessing the derotational effect of different implants and surgical strategies.

Magnetically controlled growing rods for severe spinal curvature in young children: a prospective case series.

BACKGROUND: Scoliosis in skeletally immature children is often treated by implantation of a rod to straighten the spine. Rods can be distracted (lengthened) as the spine grows, but patients need many invasive operations under general anaesthesia. Such operations are costly and associated with negative psychosocial outcomes. We assessed the effectiveness and safety of a new magnetically controlled growing rod (MCGR) for non-invasive outpatient distractions. METHODS: We implanted the MCGR in five patients, two of whom have now reached 24 months' follow-up. Each patient underwent monthly outpatient distractions. We used radiography to measure the magnitude of the spinal curvature, rod distraction length, and spinal length. We assessed clinical outcome by measuring the degree of pain, function, mental health, satisfaction with treatment, and procedure-related complications. FINDINGS: In the two patients with 24 months' follow-up, the mean degree of scoliosis, measured by Cobb angle, was 67° (SD 10°) before implantation and 29° (4°) at 24 months. Length of the instrumented segment of the spine increased by a mean of 1·9 mm (0·4 mm) with each distraction. Mean predicted versus actual rod distraction lengths were 2·3 mm (1·2 mm) versus 1·4 mm (0·7 mm) for patient 1, and 2·0 mm (0·2 mm) and 2·1 mm (0·7 mm) versus 1·9 mm (0·6 mm) and 1·7 mm (0·8 mm) for patient 2's right and left rods, respectively. Throughout follow-up, both patients had no pain, had good functional outcome, and were satisfied with the procedure. No MCGR-related complications were noted. INTERPRETATION: The MCGR procedure can be safely and effectively used in outpatient settings, and minimises surgical scarring and psychological distress, improves quality of life, and is more cost-effective than is the traditional growing rod procedure. The technique could be used for non-invasive correction of abnormalities in other disorders. FUNDING: Ellipse Technologies.

Natural history of spinal deformity in a patient with Ehlers-Danlos syndrome: case report with 20-year follow-up.

BACKGROUND CONTEXT: Scoliosis can present in patients with Ehlers-Danlos syndrome (EDS) and can be surgically treated despite possible complications. The long-term natural history of the progression of spinal deformity, particularly scoliosis, and associated complications in EDS patients remains relatively unknown. PURPOSE: To assess the progression of spinal deformity and associated complications in a patient with EDS, who was not surgically treated for her spine condition and was followed up for 20 years. STUDY DESIGN: A case report. METHODS: A 9-year-old female with EDS presented to the orthopedic clinic with scoliosis and mild thoracic hyperkyphosis. The patient was followed up for a 20-year period. Progression of her spinal deformity and associated complications were noted. RESULTS: The patient's curve progressed rapidly in the initial follow-up period an 83° worsening from the age of 9 to 10 years. Because she refused surgical intervention, her spinal deformity continued to progress. As such, by the age of 29 years, she presented with 115° from T9 to L4 with severe hyperkyphosis. The patient eventually developed respiratory compromise and diminished functional capacity. CONCLUSIONS: In patients with EDS, scoliosis may progress rapidly and unrelentingly, and if not treated early may lead to respiratory compromise. Close follow-up of such patients is imperative, and appropriate management should be sought to prevent potentially fatal morbidities.

The proximal thoracic curve in adolescent idiopathic scoliosis: surgical strategy and management outcomes.

There is no consensus on the definition of a structural proximal thoracic curve (PTC) and the indications for fusion. As such, we assessed a single institute's experience in the management of large PTCs (>35 degrees) in patients with adolescent idiopathic scoliosis (AIS) who were either fused or not fused. A retrospective radiographic analyses of 30 consecutive AIS patients with double thoracic curves who underwent PSF with a minimum of 2 years' follow-up were included for review. The patients were divided into two groups: group 1 (n = 15 patients) with fusion extended up to T2 or T3 and group 2 (n = 15) with fusion limited to T5 or below. Shoulder balance was assessed according to clavicular angle, first-rib difference, and radiographic shoulder height difference (SHD). PTCs were defined based on a Cobb angle of >35, the presence of apical rotation, and a positive T1 tilt. The decision to fuse the PTC was based on curve magnitude only, with those between 35 and 45 degrees undergoing a selective fusion of the main thoracic curve (MTC), with both curves fused if the PTC was more than 45 degrees. In group 1, there were eight females and seven males. Their ages ranged between 12 and 33 years, with a mean of 16.2 ± 5.5 years. Postoperatively, the mean PTC correction was 45.6%, which statistically differed from preoperative status (p = 0.001). No statistical difference was noted in T1 tilt and the first-rib difference from preoperative to postoperative follow-up (p > 0.05). However, the clavicular angle and SHD were increased significantly at the immediate postoperative interval (p < 0.05) but demonstrated no significant changes between the initial and the last follow-up values (p > 0.05). Group 2 consisted of one male and 14 females. The mean age was 16.4 ± 4 years (range: 11 to 28 years). The mean spontaneous PTC correction was 28.3% and remained essentially unchanged at the end of the follow-up. The improvement in the curve from preoperative status was highly statistically significant (p = 0.001). All radiographic shoulder parameters exhibited a significant increase in the immediate postoperative period and at last follow-up, and shoulder balance improvement was not noted on follow-up. Although both groups were not statistically similar with regards to the preoperative PTC, AVR, apical vertebral translation, and shoulder parameters, no significant difference could be found in PTC or shoulder parameters between both groups at last follow-up (p > 0.05). Our study illustrates important observations that should be considered in defining the PTC for fusion consideration. Spontaneous correction of the PTC occurs in structural curves greater than 35 degrees and less than 45 degrees, and this correction is maintained over time. Despite that correction, radiographic shoulder parameters are expected to slightly increase. Nonfusion strategy may be appropriate for PTCs between 35 and 45 degrees. After fusion of both the MTC and the PTC, the radiographic shoulder parameters did not significantly differ. Preoperative radiographic shoulder parameters are not predictive of postoperative shoulder imbalance.

Infective spondylitis in Southern Chinese: a descriptive and comparative study of ninety-one cases.

STUDY DESIGN: A retrospective review of infective spondylitis patients assessed at a major, tertiary referral centre in Hong Kong. OBJECTIVE: To assess the prevalence, risk factors, clinical features, and prognostic outcomes associated with tuberculous spondylitis to that of pyogenic spondylitis in Southern Chinese treated at a single institution. SUMMARY OF BACKGROUND DATA: Previous studies in Asia suggest that tuberculous spondylitis is the predominant infection unless proven otherwise. Current clinical experiences suggest otherwise; however, the current trend and clinical profile of infective spondylitis among Southern Chinese remains speculative with no published studies examining their prevalence. METHODS: A retrospective review was performed of all infective spondylitis cases presenting from January 2004 to July 2008 to a tertiary referral center. Cases were included on the basis of clinical and microbiological criteria. Radiographic imaging was used for further confirmation. RESULTS: Ninety-one patients were identified. Overall, tuberculous spondylitis and pyogenic spondylitis entailed 22 (24.2%) and 69 (75.8%) cases, respectively. Staphylococcus aureus was the most commonly isolated infective agent associated with pyogenic spondylitis. Individuals with pyogenic spondylitis were significantly much older than those with tuberculous spondylitis (P = 0.001). Intravenous drug addiction was the most commonly noted risk factor followed by diabetes, and found to be more prevalent in pyogenic spondylitis cases. At initial presentation, white cell count and c-reactive protein levels were higher in pyogenic spondylitis cases compared with tuberculous spondylitis (P < 0.05). The occurrence of tuberculous spondylitis cases was predominant in the thoracic region (40.9%) (P < 0.05). Surgical intervention was performed in 54.5% of tuberculous spondylitis and in 24.6% of the pyogenic spondylitis cases (P = 0.009). CONCLUSION: In Southern Chinese, compared to previous reports over the past 3 decades, a changing prevalence of decreasing tuberculous spondylitis was observed. Pyogenic spondylitis was found to be more common among patients hospitalized for infective spondylitis. This has important implications on the method of diagnosis and the need for establishing microbiological diagnosis before commencing treatment. "Best guess" therapy should not be targeted at tuberculous spondylitis only. There are clear distinctions in the biologic and clinical profiles between tuberculous and pyogenic spondylitis that would help to direct therapy.

Predictability of the fulcrum bending radiograph in scoliosis correction with alternate-level pedicle screw fixation.

BACKGROUND: The fulcrum bending radiograph accurately predicts scoliosis curve correction in patients with thoracic adolescent idiopathic scoliosis who are managed with hooks. We assessed the predictive value of the fulcrum bending radiograph in the context of alternate-level pedicle screw fixation of the scoliotic spine. METHODS: A prospective radiographic analysis of patients with thoracic adolescent idiopathic scoliosis who were managed operatively with alternate-level pedicle screw fixation at a single institution was performed. The Cobb angle was measured on posteroanterior standing coronal radiographs that were made preoperatively and one week postoperatively. The fulcrum flexibility percentage and the fulcrum bending correction index percentage were calculated. RESULTS: Forty-two patients were assessed. The mean age at the time of surgery was 14.6 years, and the mean number of fused levels was 9.4. On the preoperative radiographs, the mean values for the standing Cobb angle, the fulcrum bending radiograph Cobb angle, and fulcrum flexibility were 57.9 degrees, 21.8 degrees, and 62.7%, respectively. On the one-week postoperative radiographs, the mean Cobb angle was 15.4 degrees, the mean curve correction was 73.4%, and the mean fulcrum bending correction index was 122.1%. A significant, positive correlation was noted between the fulcrum bending radiograph angle and the fulcrum bending correction index, indicating that the fulcrum bending radiograph could predict the correction of flexible curves; however, for stiff curves, pedicle screws could provide more correction than the fulcrum bending radiograph predicted. CONCLUSIONS: To our knowledge, this is the first study to demonstrate the predictive value of the fulcrum bending radiograph in the context of alternate-level pedicle screw fixation in patients with adolescent idiopathic scoliosis. Curve flexibility may dictate the degree of the fulcrum bending correction index, whereby a curve that is less flexible may achieve a greater fulcrum bending correction index. The fulcrum bending radiograph has potential predictive utility. In addition, pedicle screw constructs appear to have a better ability to correct scoliosis in comparison with hooks and hybrid constructs.

A gait stability investigation into FES-assisted paraplegic walking based on the walker tipping index.

The gait outcome measures used in clinical trials of paraplegic locomotor training determine the effectiveness of improved walking function assisted by the functional electrical stimulation (FES) system. Focused on kinematic, kinetic or physiological changes of paraplegic patients, traditional methods cannot quantify the walking stability or identify the unstable factors of gait in real time. Up until now, the published studies on dynamic gait stability for the effective use of FES have been limited. In this paper, the walker tipping index (WTI) was used to analyze and process gait stability in FES-assisted paraplegic walking. The main instrument was a specialized walker dynamometer system based on a multi-channel strain-gauge bridge network fixed on the frame of the walker. This system collected force information for the handle reaction vector between the patient's upper extremities and the walker during the walking process; the information was then converted into walker tipping index data, which is an evaluation indicator of the patient's walking stability. To demonstrate the potential usefulness of WTI in gait analysis, a preliminary clinical trial was conducted with seven paraplegic patients who were undergoing FES-assisted walking training and seven normal control subjects. The gait stability levels were quantified for these patients under different stimulation patterns and controls under normal walking with knee-immobilization through WTI analysis. The results showed that the walking stability in the FES-assisted paraplegic group was worse than that in the control subject group, with the primary concern being in the anterior-posterior plane. This new technique is practical for distinguishing useful gait information from the viewpoint of stability, and may be further applied in FES-assisted paraplegic walking rehabilitation.

Risk-tendency graph (RTG): a new gait-analysis technique for monitoring FES-assisted paraplegic walking stability.

BACKGROUND: Gait analysis techniques guide the use and design of functional electrical stimulation (FES) systems for paraplegic walking. However, published studies on dynamic gait stability for the effective use of FES are limited. This paper introduces a new risk-tendency graph (RTG) technique to analyze and process gait stability in FES-assisted paraplegic walking. MATERIAL/METHODS: The main instrument was a specialized walker dynamometer system based on a multi-channel strain-gauge bridge network affixed to the frame of the walker. This system collects force information for the handle reaction vector (HRV) between the patient's upper extremities and the walker during walking. The information is then converted into a walker tipping index (WTI), which is an indicator of the patient's walking stability. Dynamic gait stability is then combined with spatio-temporal locating methods for WTI and visually described as morphological curves in the temporal and spatial domains, namely RTGs. RESULTS: To demonstrate the potential usefulness of RTG in gait analysis, a preliminary clinical trial was conducted with one male paraplegic patient who was undergoing FES walking training. The gait stability levels for the patient under different stimulation patterns were quantified using the results of temporal and 3-D spatial RTG. Relevant instable phases in the gait cycle and dangerous inclinations of the patient's body while walking were also clearly identified. CONCLUSIONS: The new RTG technique is a practical method for distinguishing useful gait information from the viewpoint of stability and may be further applied in FES-assisted paraplegic walking rehabilitation.