The effect of posterior compression of the facet joints for initial stability and sagittal profile in the treatment of thoracolumbar fractures: a biomechanical study

Purpose Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation—in neutral position or distraction—potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. Methods Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12–L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb’s angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. Results We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. Conclusion Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies.

Minimally invasive anteroposterior combined surgery using lateral lumbar interbody fusion without corpectomy for treatment of lumbar spinal canal stenosis associated with osteoporotic vertebral collapse

OBJECTIVE Various reconstructive surgical procedures have been described for lumbar spinal canal stenosis (LSCS) with osteoporotic vertebral collapse (OVC); however, the optimal surgery remains controversial. In this study, the authors aimed to report the clinical and radiographic outcomes of their novel, less invasive, short-segment anteroposterior combined surgery (APCS) that utilized oblique lateral interbody fusion (OLIF) and posterior fusion without corpectomy to achieve decompression and reconstruction of anterior support in patients with LSCS-OVC. METHODS In this retrospective study, 20 patients with LSCS-OVC (mean age 79.6 years) underwent APCS and received follow-up for a mean of 38.6 months. All patients were unable to walk without support owing to severe low-back and leg pain. Cleft formations in the fractured vertebrae were identified on CT. APCS was performed on the basis of a novel classification of OVC into three types. In type A fractures with a collapsed rostral endplate, combined monosegment OLIF and posterior spinal fusion (PSF) were performed between the collapsed and rostral adjacent vertebrae. In type B fractures with a collapsed caudal endplate, combined monosegment OLIF and PSF were performed between the collapsed and caudal adjacent vertebrae. In type C fractures with severe collapse of both the rostral and caudal endplates, bisegment OLIF and PSF were performed between the rostral and caudal adjacent vertebrae, and pedicle screws were also inserted into the collapsed vertebra. Preoperative and postoperative clinical and radiographical status were reviewed. RESULTS The mean number of fusion segments was 1.6. Walking ability improved in all patients, and the mean Japanese Orthopaedic Association score for recovery rate was 65.7%. At 1 year postoperatively, the mean preoperative Oswestry Disability Index of 65.6% had significantly improved to 21.1%. The mean local lordotic angle, which was −5.9° preoperatively, was corrected to 10.5° with surgery and was maintained at 7.7° at the final follow-up. The mean corrective angle was 16.4°, and the mean correction loss was 2.8°. CONCLUSIONS The authors have proposed using minimally invasive, short-segment APCS with OLIF, tailored to the morphology of the collapsed vertebra, to treat LSCS-OVC. APCS achieves neural decompression, reconstruction of anterior support, and correction of local alignment.

Finite Element Analysis of Stability of Internal Fixation Reconstruction Methods for Lumbar Total Vertebral Resection

Objective To compare the effect of different fixation methods on spinal stability after total en bloc spondylectomy(TES) of lumbar spine.Method The finite element models were established based on the CT scan of a healthy volunteer. After the validity of the models was confirmed, the models with different posterior fixation methods of the lumbar spine were established with and without the artificial vertebral body, respectively. The motions of flexion, extension, lateral bending and rotation under supine and standing conditions were simulated. The angular displacement of T11-L3 and stress of internal fixations were compared and analyzed.Results The finite element models of spinal reconstruction after TES were obtained. When the anterior support existed, the movement of the spine after TES was not affected by the gravity of the upper body. The movements in the opposite direction on the same plane were similar. All three methods provided enough stability to the spine. The improved short-segment fixation shared stress of the artificial vertebral body with no obvious negative effect. The long-segment fixation had stronger fixation effect with the huge loss of the range of motion of lumbar spine. When the anterior support failed, obvious rotation showed in lateral bending in all models. The short-segment fixation and the long-segment fixation failed to maintain the spinal stability with fixations breakage or functional loss. The improved short-segment fixations showed strong ability in maintaining the spinal stability. The vertebral body screws can prevent the failure of anterior fixation by sharing great stress of the whole internal fixation system. The improved short-segment had huge advantages over the others.Conclusion After TES, the improved short-segment fixation can provide more stability to the spine. The vertebral body screws can prevent the failure of the internal fixation by reducing the stress of the anterior support. This fixation method should be promoted in clinical practice while the effect requires more observation.

Design and Development of a Wearable Exoskeleton System for Stroke Rehabilitation

For more than a decade, many countries have been actively developing robotic assistive devices to assist in the rehabilitation of individuals with limb disability to regain function in the extremities. The exoskeleton assistive device in this study has been designed primarily for hemiplegic stroke patients to aid in the extension of fingers to open up the palm to simulate the effects of rehabilitation. This exoskeleton was designed as an anterior-support type to achieve palmar extension and acts as a robotic assistive device for rehabilitation in bilateral upper limb task training. Testing results show that this wearable exoskeleton assistive device with human factor consideration using percentile dimensions can provide comfortable wear on patients as well as adequate torque to pull individual fingers into flexion towards the palm for rehabilitation. We hope this exoskeleton device can help stroke patients with loss of function in the upper extremities to resume motor activities in order to maintain activities of daily living.

Evaluation of the effectiveness of expandable cages for reconstruction of the anterior column of the spine

Purpose: For anterior spine column reconstruction after corpectomy, expandable cages offer solid anterior support and allow correction of deformity, providing excellent primary stability. To provide a larger body of clinical observations concerning the effectiveness of the approach, this retrospective study examines patients treated by corpectomy and reconstruction with an expandable cage for different pathologies. Methods: Across 5 years, 39 patients underwent vertebral reconstruction with expandable cages after single ( n = 34), double ( n = 4), or triple ( n = 1) corpectomy. Pathologies were tumors ( n = 21), fractures, or deformities in traumatic injuries ( n = 14), degenerative pathology ( n = 2), and infection ( n = 2). Levels were cervical ( n = 10), thoracic ( n = 14), and lumbar ( n = 15). All patients were evaluated clinically and radiographically. Results: There were no cases of neurologic deterioration. Nurick grade showed significant improvement at 3 months postoperative versus preoperative ( p < 0.01). Visual analog scale significantly improved preoperatively versus 3 and 12 months postoperatively (both p = 0). Regional angulation was significantly corrected, from preoperative to 3 and 12 months postoperative, at cervical, thoracic, and lumbar levels. We achieved reconstruction of the normal local anatomy with full recovery of the height of the vertebral body. Six patients (15.4%) had complications and two (5.1%) underwent revision surgery. Conclusions: In our experience, expandable cages confer stable anterior support, providing significant improvement of the segmental kyphosis angle and restoration of the original somatic height. Our clinical results are favorable, and the low rate of complications and revision accentuates the expandable cage as a valuable tool to replace the vertebral body in diverse pathologies and different spine levels.

Comparative study of anterior support ankle foot orthosis and posterior ankle foot orthosis in foot drop patients

Background: Anterior Support Ankle Foot Orthosis (A-AFO) is a fairly recent approach. There is dearth of studies relating to comparison of metabolic efficiency of A-AFO and P-AFO. Objective was to study the efficacy of A-AFO compared to P-AFO in foot drop patients, using gait and metabolic analysis.Methods: It was a cross over study, included foot drop patients who could walk with/ without orthosis. Patients having spasticity more than grade 2 (Modified Ashworth Scale) were excluded. The metabolic parameters measured were volume of Oxygen consumed at Standard Temperature and Pressure in l/min (VO2), Dry in l/min, Rate of Oxygen consumption (MET), Volume of Carbon dioxide produced in litre/min (VCO2). Along with various gait parameters, questionnaire about patient’s preference after 4 weeks was also incorporated.Results: A-AFO was significantly better than P-AFO in terms of VO2 and VCO2 (p value = 0.02 and 0.009 respectively) as well as in terms of subjective preference.Conclusions: A-AFO is comparable to P-AFO in terms of energy efficiency, gait parameters and subjective preference, hence should also be prescribed.

COMPLICATED LUMBAR TUBERCULOUS SPONDYLODISCITIS IN DISSEMINATED TUBERCULOSIS, TREATED USING A NON-CONVENTIONAL ANTERIOR SUPPORT SYSTEM FOR HYDROSTATIC DISTRACTION: A CASE REPORT

ABSTRACT Objective: To describe a case of disseminated tuberculosis affecting the lumbar spine that was treated using a non-conventional anterior support system. Background: Tuberculous spondylodiscitis is the most common and most severe form of extrapulmonary tuberculosis. Although antibiotic therapy is the most frequently used treatment, surgery is necessary in cases of neurological deficit, spinal instability, significant deformity, severe sepsis, paravertebral and epidural abscesses or in cases wherein clinical treatment has failed. A surgical procedure is also indicated when a biopsy is required. With the development of new methods for reconstruction and fixation of the spine, complete debridement of the tuberculous foci has become an increasingly common approach, but there is a lack consensus on the best technique. Methods and results: The patient suffered from disseminated tuberculosis affecting the lumbar region of the spine, with an abscess in the psoas muscle. He underwent extensive debridement via both anterior and posterior approaches, using a non-conventional anterior support system that promotes hydrostatic distraction. Conclusions: Treatment using the hydrostatic distraction system was able to reestablish both the stability and anatomy of the lumbar curve. Level of evidence IV, Case report.