A Novel Application of Deep Learning (Convolutional Neural Network) for Traumatic Spinal Cord Injury Classification Using Automatically Learned Features of EMG Signal

In this study, a traumatic spinal cord injury (TSCI) classification system is proposed using a convolutional neural network (CNN) technique with automatically learned features from electromyography (EMG) signals for a non-human primate (NHP) model. A comparison between the proposed classification system and a classical classification method (k-nearest neighbors, kNN) is also presented. Developing such an NHP model with a suitable assessment tool (i.e., classifier) is a crucial step in detecting the effect of TSCI using EMG, which is expected to be essential in the evaluation of the efficacy of new TSCI treatments. Intramuscular EMG data were collected from an agonist/antagonist tail muscle pair for the pre- and post-spinal cord lesion from five Macaca fasicularis monkeys. The proposed classifier is based on a CNN using filtered segmented EMG signals from the pre- and post-lesion periods as inputs, while the kNN is designed using four hand-crafted EMG features. The results suggest that the CNN provides a promising classification technique for TSCI, compared to conventional machine learning classification. The kNN with hand-crafted EMG features classified the pre- and post-lesion EMG data with an F-measure of 89.7% and 92.7% for the left- and right-side muscles, respectively, while the CNN with the EMG segments classified the data with an F-measure of 89.8% and 96.9% for the left- and right-side muscles, respectively. Finally, the proposed deep learning classification model (CNN), with its learning ability of high-level features using EMG segments as inputs, shows high potential and promising results for use as a TSCI classification system. Future studies can confirm this finding by considering more subjects.

Neurophysiological Characterization of a Non-Human Primate Model of Traumatic Spinal Cord Injury Utilizing Fine-Wire EMG Electrodes

This study aims to characterize traumatic spinal cord injury (TSCI) neurophysiologically using an intramuscular fine-wire electromyography (EMG) electrode pair. EMG data were collected from an agonist-antagonist pair of tail muscles of Macaca fasicularis, pre- and post-lesion, and for a treatment and control group. The EMG signals were decomposed into multi-resolution subsets using wavelet transforms (WT), then the relative power (RP) was calculated for each individual reconstructed EMG sub-band. Linear mixed models were developed to test three hypotheses: (i) asymmetrical volitional activity of left and right side tail muscles (ii) the effect of the experimental TSCI on the frequency content of the EMG signal, (iii) and the effect of an experimental treatment. The results from the electrode pair data suggested that there is asymmetry in the EMG response of the left and right side muscles (p-value < 0.001). This is consistent with the construct of limb dominance. The results also suggest that the lesion resulted in clear changes in the EMG frequency distribution in the post-lesion period with a significant increment in the low-frequency sub-bands (D4, D6, and A6) of the left and right side, also a significant reduction in the high-frequency sub-bands (D1 and D2) of the right side (p-value < 0.001). The preliminary results suggest that using the RP of the EMG data, the fine-wire intramuscular EMG electrode pair are a suitable method of monitoring and measuring treatment effects of experimental treatments for spinal cord injury (SCI).

Model of Traumatic Spinal Cord Injury for Evaluating Pharmacologic Treatments in Cynomolgus Macaques (Macaca fasicularis)

Here we present the results of experiments involving cynomolgus macaques, in which a model of traumatic spinal cord injury (TSCI) was created by using a balloon catheter inserted into the epidural space. Prior to the creation of the lesion, we inserted an EMG recording device to facilitate measurement of tail movement and muscle activity before and after TSCI. This model is unique in that the impairment is limited to the tail: the subjects do not experience limb weakness, bladder impairment, or bowel dysfunction. In addition, 4 of the 6 subjects received a combination treatment comprising thyrotropin releasing hormone, selenium, and vitamin E after induction of experimental TSCI. The subjects tolerated the implantation of the recording device and did not experience adverse effects due the medications administered. The EMG data were transformed into a metric of volitional tail moment, which appeared to be valid measure of initial impairment and subsequent natural or treatment-related recovery. The histopathologic assessment demonstrated widespread axon loss at the site of injury and areas cephalad and caudad. Histopathology revealed evidence of continuing inflammation, with macrophage activation. The EMG data did not demonstrate evidence of a statistically significant treatment effect.

Reduced variability of acetabular cup positioning with use of an imageless navigation system

Positioning the acetabular component is one of the most important steps in total hip arthroplasty; malpositioned components can result in dislocations, impingement, limited range of motion, and increased polyethylene wear. Conventional surgery makes use of specialized alignment guides provided by the manufacturers of the implants. The use of mechanical guides has been shown to result in large variations of cup inclination and version. We investigated acetabular cup alignment with the nonimage-based hip navigation system compared with a conventional mechanically guided procedure in 12 human cadavers. Postoperative cup position relative to the pelvic reference plane was assessed in both groups with the use of a three-dimensional digitizing arm. In the navigated group, a median inclination of 45.5 degrees and a median anteversion of 21.9 degrees (goals, 45 degrees and 20 degrees) were reached. In the control group, the median inclination was 41.8 degrees and the median anteversion was 24.6 degrees. The ninetieth percentile showed a much wider range for the control group (36.1 degrees-51.8 degrees inclination, 15 degrees-33.5 degrees anteversion) than for the navigated group (43.9 degrees-48.2 degrees inclination, 18.3 degrees-25.4 degrees anteversion). This cadaver study shows that computer-assisted cup positioning using a nonimage-based hip navigation system allowed for more consistent placement of the acetabular component.

Similarities and differences in the treatment of spine trauma between surgical specialties and location of practice

STUDY DESIGN

Questionnaires administered to practicing orthopedic and neurosurgical spine surgeons from various regions of the United States and abroad.

OBJECTIVES

To determine similarities and differences in the treatment of spinal trauma.

SUMMARY OF BACKGROUND DATA

Spinal trauma is generally referred to subspecialists of orthopedic or neurosurgical training. Prior studies have suggested that there is significant variability in the management of such injuries.

METHODS

Questionnaires based on eight clinical scenarios of commonly encountered cervical, thoracic, and lumbar injuries were administered to 35 experienced spinal surgeons. Surgeons completed profile information and answered approximately one dozen questions for each case. Data were analyzed with SPSS software to determine the levels of agreement and characteristics of respondents that might account for a lack of agreement on particular aspects of management.

RESULTS

Of the 35 surgeons completing the questionnaire, 63% were orthopedists, 37% were neurosurgeons, and 80% had been in practice for more than 5 years. Considerable agreement was found in the majority of clinical decisions, including whether or not to operate and the timing of surgery. Of the differences noted, neurosurgeons were more likely to obtain a MRI, and orthopedists were more likely to use autograft as a sole graft material. Physicians from abroad were, in general, more likely to operate and to use an anterior approach during surgery than physicians from the northeastern United States.

CONCLUSIONS

More commonalities were identified in the management of spinal trauma than previously reported. When found, variability in opinion was related to professional and regional differences.

The acetabular blood supply: implications for periacetabular osteotomies

As the popularity of juxta-acetabular osteotomies in adults increases, concern arises that such a procedure will potentially cause avascular necrosis of the acetabular fragment. In order to verify the remaining vascularization after a Bernese periacetabular osteotomy, an injection study with colored latex was performed. The vascularity of the outside of the periacetabular bone was studied in 16 hips after injection of colored latex into the abdominal aorta and the inside in four hips. To confirm the conclusions drawn from the anatomic study, a Bernese periacetabular osteotomy was performed in two additional hips after latex injection. This study demonstrated that through a modified Smith-Peterson approach and with execution of the osteotomies from the inside of the pelvis the acetabular fragment remains vascularized by the supra-acetabular and acetabular branches of the superior gluteal artery, the obturator artery and the inferior gluteal artery. Some uncertainty remains about how much correction is tolerated by the smaller blood vessels.

Traumatic labral avulsion from the stable rim: a constant pathology in displaced transverse acetabular fractures

INTRODUCTION

During the treatment of a malunited transverse acetabular fracture, a hitherto undescribed extended avulsion of the labrum from the stable acetabular fragment was found. Based on the labral pathomorphology present in this case, the hypothesis was put forward that traumatic acetabular labral avulsions are a constant phenomenon in transverse acetabular fractures.

PATIENTS AND METHODS

Fourteen patients underwent capsulotomy and/or surgical dislocation of the involved hip to facilitate open reduction and internal fixation of transverse acetabular fractures.

RESULTS

In all cases, the labrum was partially or completely detached from the superior acetabular rim. In eight cases with bucket-handle tears of the labrum from the stable superior fragment, the injured portion was resected back to normal margins. In one case the labrum was avulsed with an attached piece of bone and was repaired by screw fixation. Small separations of the labrum from the underlying acetabular rim occurred at the level of the fractures in five cases with minor displacement and received no treatment.

CONCLUSION

With displaced transverse acetabular fractures, consideration should be given to opening the joint at the time of open reduction and internal fixation to look for associated intracapsular injuries. An avulsed portion of the labrum should be left if stable and undamaged. If unstable and damaged, it is probably better resected and if unstable but intact and/or attached to a bony fragment, it should be repaired.

An algorithm for the treatment of Vancouver type B2 periprosthetic proximal femoral fractures

The number of individuals with periprosthetic fractures of the proximal part of the femur is increasing. Multiple treatment methods have been described but none that correlate to fracture type and few with mostly good-to-excellent results. This article describes an algorithmic reconstruction tactic for treating patients with periprosthetic fractures associated with a loose femoral component. The stem is approached through the fracture fragments. Reconstructing the tube of the proximal part of the femur with 18G cerclage wires allows for canal preparation and implantation of the new stem. Application of the allograft struts and cables maximizes the biomechanical integrity of the proximal part of the femur to promote fracture repair and implant fixation. No treatment failures have occurred as of this date.

Irreducible dislocations of the cervical spine with a prolapsed disc: preliminary results from a treatment technique

STUDY DESIGN

The preliminary results from a treatment technique for irreducible dislocations of the cervical spine with prolapsed disk are reported.

OBJECTIVE

To report the success of a technique for grafting and instrumentation of the anterior cervical spine before reduction. This technique is useful in cervical fracture-dislocations irreducible through the anterior approach that must be approached first from the front because of a prolapsed disc.

SUMMARY OF BACKGROUND DATA

In the treatment of cervical facet dislocations, a third anterior procedure often is necessary to accomplish the anterior instrumentation and fusion. The reported technique describes a method that eliminates this third procedure by using a cervical buttress plate.

METHODS

Between August of 1996 and October 1998, four patients had dislocation of the cervical spine with a prolapsed disc that could not be reduced using the anterior approach. After discectomy and endplate preparation, a tricortical bone graft was harvested from the iliac crest, placed in the interspace, and held with a buttress plate screwed in two places into the superior vertebral body. The anterior wound then was closed. The posterior elements were exposed and the facets reduced by flexing the neck and posteriorly translating the superior segment. Fluoroscopy was used during the reduction to ensure that the graft was pulled into the interspace, that the screws in the buttress plate did not pull out of the superior vertebral body, and that the reduced graft did not impinge on the spinal cord. A posterior fusion was performed and the posterior wound closed.

RESULTS

All the patients had consolidation of both anterior and posterior fusions. No cases of instrument failure occurred, either anteriorly or posteriorly. No cases of neurologic deterioration occurred, and no complications were attributable to the use of this technique.

CONCLUSION

The reported technique was used successfully in the treatment of four patients with irreducible dislocations of the cervical spine.

Use of magnetic resonance imaging in evaluating injuries to the pediatric thoracolumbar spine

Magnetic resonance imaging (MRI) of acute thoracolumbar spinal injuries allows excellent evaluation of the neurologic and soft tissue structures. Owing to recent advances in imaging techniques that permit greater spatial resolution and more detailed imaging of tissue, MRI now affords effective visualization of injury to the ligaments, intervertebral disk, bones, and spinal cord after spine trauma. Cord changes have been classified into three patterns that are predictive of clinical outcomes in adults with cord injuries. The value of MRI in evaluating pediatric patients with thoracolumbar injuries or in predicting their clinical outcome has not been assessed. After retrospectively reviewing 19 pediatric thoracolumbar fractures associated with neurologic deficits from three level 1 trauma centers, we conclude that MRI is the imaging modality of choice in these patients because it can accurately classify injury to bones and ligaments and because the cord patterns as determined by MRI have predictive value.

The anatomy and function of the gluteus minimus muscle

In order to investigate the functional anatomy of gluteus minimus we dissected 16 hips in fresh cadavers. The muscle originates from the external aspect of the ilium, between the anterior and inferior gluteal lines, and also at the sciatic notch from the inside of the pelvis where it protects the superior gluteal nerve and artery. It inserts anterosuperiorly into the capsule of the hip and continues to its main insertion on the greater trochanter. Based on these anatomical findings, a model was developed using plastic bones. A study of its mechanics showed that gluteus minimus acts as a flexor, an abductor and an internal or external rotator, depending on the position of the femur and which part of the muscle is active. It follows that one of its functions is to stabilise the head of the femur in the acetabulum by tightening the capsule and applying pressure on the head. Careful preservation or reattachment of the tendon of gluteus minimus during surgery on the hip is strongly recommended.

The management of severe acetabular bone loss using structural allograft and acetabular reinforcement devices

The cases of 37 acetabular reconstructions in 35 patients with major structural pelvic bone loss were reviewed. At an average follow-up of 7.1 years, patients rated their results as excellent in 12 cases (32.4%), good in 22 (59.5%), fair in 2 (5.4%), and poor in 1 (2.7%). Thirty-four cases (91.9%) were classified as a clinical success. Thirty-six allografts (97.3%) had radiographic evidence of full incorporation. Of the unrevised hips, 1 (2.7%) was classified as definitely loose, 2 (5.4%) as probably loose, and 4 (10.8%) as possibly loose. One revision of an acetabular component was required because of late sepsis. This is the first reported series on the use of acetabular reinforcement devices with solid bulk allograft covering more than 50% of the socket. The allograft is protected in the early postoperative period, superior migration of the cup is virtually eliminated as a complication, and the incidence of aseptic loosening is greatly diminished.

Lateral insufficiency fractures of the femur caused by osteopenia and varus angulation: a complication of total hip arthroplasty

Lateral femoral insufficiency fractures in total hip arthroplasty occur due to osteopenia and varus positioning of the femoral component, the femur itself, or both. The presentation of these fractures can be unclear but usually involves the insidious onset of unexplained thigh or groin pain. The patients are likely to have significant comorbidities as well. Characteristic radiographic findings may be present, depending on when the patient presents. The insufficiency fractures generally occur at the level of the femoral stem tip on the lateral cortex of the femur. If left untreated, pain and loss of function continue. Eventually an insufficiency fracture can progress to a displaced periprosthetic fracture. Nonsurgical treatment is not successful. Recommended treatment involves revision to a long-stem femoral component. The risk of postoperative complications is significant.

The Bürch-Schneider anti-protrusio cage in revision total hip arthroplasty: indications, principles and long-term results

Patients who had a revision total hip arthroplasty using the Bürch-Schneider anti-protrusio cage (APC) by a single surgeon have been reviewed after a minimum of five years. There were 63 operations in 58 patients with an average age of 63 years (41 to 83) at the time of revision. At an average follow-up of 8.5 years (5 to 18), 15 patients (25.9%) rated their results as excellent, 38 (65.5%) as good, and five (8.6%) as fair. Five further revisions of the acetabular prosthesis were required, three due to aseptic loosening, one for recurrent dislocation and one due to sepsis. Of the remainder, one was definitely loose, two probably loose, and 12 possibly so. Impressive augmentation of bone stock can be achieved with the anti-protrusio cage, while enabling the hip to be centred in its anatomical position.

Intraoperative assessment of femoral head vascularity after femoral neck fracture

OBJECTIVES

To develop an intraoperative technique to predict the development of avascular necrosis after internal fixation of femoral neck fractures.

DESIGN

Prospective study.

SETTING

All patients were treated at the same hospital.

PATIENTS/PARTICIPANTS

Sixty-four patients who presented for internal fixation of a femoral neck fracture were enrolled in the study.

INTERVENTION

A 2.0-millimeter drill was used to assess the presence and character of bleeding from the femoral head at open reduction and internal fixation of a femoral neck fracture.

MAIN OUTCOME MEASUREMENTS

Patients were evaluated postoperatively by history, examination, and roentgenography for the development of avascular necrosis of the femoral head fragment. A minimum two-year follow-up with radiography was required for entry into the study, with an average follow-up of 3.2 years.

RESULTS

None of the fifty-six patients with bleeding from the drill holes in the femoral head fragment developed avascular necrosis. Eight of eight patients with no bleeding after reduction developed avascular necrosis. There were no infections or nonunions.

CONCLUSIONS

Intraoperative drilling of the femoral head is a highly sensitive and specific predictor for the development of avascular necrosis after femoral neck fractures.

Total hip arthroplasty with use of an acetabular reinforcement ring in patients who have congenital dysplasia of the hip. Results at five to fifteen years

The purpose of our study was to examine the clinical and technical problems associated with reconstruction of the hip in patients who had congenital dysplasia and to offer recommendations for their solution. We reviewed the records on 123 consecutive total hip arthroplasties that had been performed by one of us (M. E. M.), between 1981 and 1986, for the treatment of coxarthrosis due to congenital dysplasia of the hip. A minimum of five years of follow-up was required for inclusion in the study. The study group consisted of seventy patients who had had a total of eighty-seven reconstructions. According to the classification of Crowe et al., eleven hips had type-IV acetabular dysplasia; sixty-five, type-II; and eleven, type-II. Acetabular reconstruction was performed with use of the Müller acetabular roof-reinforcement ring and a polyethylene cup, which was inserted with cement. Autologous graft from the femoral head was used in forty-two hips. Femoral reconstruction was performed with use of the Müller straight-stem component for congenital dysplasia of the hip in eighty hips and with use of a standard Müller straight-stem component in seven hips. At an average of 9.4 years (range, five to fifteen years) postoperatively, the result was described as excellent for sixty hips (69 per cent), as good for twenty-three (26 per cent), as fair for two (2 per cent), and as poor for two. Nine (10 per cent) of the hips had been revised. One revision had been performed because of aseptic loosening of the acetabular component; one, because of aseptic loosening of the femoral component; one, because of aseptic loosening of both components; and six, because of infection. Of the unrevised hips, three had had superior migration of the acetabular component of less than five millimeters, and mild protrusion had developed in one. Two hips had a continuous radiolucent line around the acetabular construct. Two hips had had subsidence of the femoral stem of less than three millimeters; one had a complete, non-progressive radiolucent line at the bone-cement interface; and four had a radiolucent line at the proximal part of the bone-cement interface. Six hips had evidence of endosteal osteolysis. Six hips had grade-III or IV heterotopic ossification according to the system of Brooker et al. These results compare favorably with others in the literature. We recommend restoration of the anatomical hip center with the use of an acetabular roof-reinforcement ring and a polyethylene cup inserted with cement for the reconstruction of a deficient acetabulum. The acetabular reinforcement ring prevents resorption of bone graft and migration of the cup, which are major causes of failure of the cup in patients who have had a reconstruction of a deficient acetabulum. Bone graft should be used medially and superiorly as needed to augment bone stock notably. Cement should not be used to fill acetabular defects as we believe that it contributes to aseptic loosening.