Shinichi Imura

Late radiographic findings after anterior cervical fusion for spondylotic myeloradiculopathy

A retrospective study was performed to evaluate the radiographic changes that occurred at spinal levels adjacent to fused vertebrae after anterior cervical fusion. One hundred six patients with cervical spondylotic myeloradiculopathy (88 men, 18 women) were followed for an average of 8.5 years. The average age at follow-up was 64 years. Forty-two patients underwent a single-level fusion, 52 had a two-level fusion, and 12 had three levels fused. Seventeen patients who underwent additional surgery after anterior fusion also were reviewed, with an average follow-up period of 2.9 years. Postoperatively, cervical flexion-extension resulted in significantly increased movement about the vertebral interspace at the upper adjacent level. An increment of posterior slip of the vertebra immediately above the fusion level, with associated spinal canal compromise of less than 12 mm, significantly affected neurologic results. Patients with multilevel fusions notably exhibited these radiographic abnormalities at adjacent levels. Spinal canal stenosis, when associated with dynamic spinal canal stenosis in the vertebra above the fusion level, affected late neurologic results. Results of salvage laminoplasty were not satisfactory. Unnecessarily extended longer fusion must be avoided.

Lordotic alignment and posterior migration of the spinal cord following en bloc open-door laminoplasty for cervical myelopathy: A magnetic resonance imaging study

We investigated lordotic alignment and posterior migration of the spinal cord following en bloc open-door laminoplasty for cervical myelopathy. Fifty-five patients (32 men and 23 women) were studied, with an average follow-up of 2.4 years. Radiological examination included evaluation of lordosis of the cervical spine and spinal cord, degree of enlargement of bony spinal canal, and the magnitude of posterior cord migration. We also correlated these changes with neurological improvement. Postoperatively, there was an average of 5% loss of cervical spine lordosis (P > 0.01) on radiographs and 12% reduction in the lordotic alignment of the spinal cord (P > 0.05) on magnetic resonance imaging. Postoperatively, the size of the bony spinal canal increased by 48%. Posterior cord migration showed a significant correlation with the preoperative cervical spine and spinal cord lordosis (P < 0.05). Thirty-seven (67%) patients with neurological improvement exceeding 50% showed significant posterior cord migration following laminoplasty compared with those demonstrating less than 50% improvement (P = 0.01). Our results suggest that a significant neurological improvement is associated with posterior cord migration after cervical laminoplasty.

Relationship between gait and clinical results after high tibial osteotomy

Thirty-two patients with primary osteoarthritis of the medial compartment of the knee were studied prospectively to assess the relationship between clinical results, limb alignment, and adduction moment of the knee. Clinical and radiographic examination and gait analyses were performed preoperatively and repeated at 6 months and at 1, 3, and 6 years after high tibial osteotomy. The preoperative peak adduction moment was high in 25 patients and low in seven. In both groups, the adduction moment of the knee decreased at 6 months after surgery but increased after that period. Alignment of the affected knee in both groups remained valgus after surgery (average femorotibial angle, 167°-169°). Clinical outcome in both groups improved after surgery and remained unchanged after 1 year. The peak adduction moment of the knee for the whole group significantly correlated with alignment and foot angle before and 6 years after surgery but did not correlate with stride length and walking velocity. In addition, only alignment was associated significantly with clinical results at 6 years. These results suggest that the preoperative peak adduction moment of the knee does not correlate with clinical or radiographic outcomes of high tibial osteotomy, provided sufficient valgus alignment is achieved at surgery.

Osteoporotic vertebral collapse with late neurological complications

This paper describes 27 patients who had a spinal fracture and underwent an anterior or a posterior spinal decompression, with or without spinal instrumentation, for late neurological compromise secondary to post-traumatic vertebral collapse associated with osteoporosis. Five males and 22 females were studied, with an average follow-up of 3.7 years. The patients developed delayed neurological compromise due to osteoporotic vertebral collapse 1 month to 1.5 years following insignificant spinal fractures. Abnormal hypermobility at the collapsed spinal level with gradual retropulsion of fracture fragments into the spinal canal appeared to contribute to late paralysis. This pathology is treated surgically either anteriorly or posteriorly, but we recommend transpedicular posterolateral decompression and stabilization with a screw-rod construct because of technical ease and minimum invasion.

Femoral deformity in adults with developmental hip dysplasia.

Quantitative computed tomography and 3 dimensional modeling were used to portray the deformity of the proximal femur in 24 Japanese adults with low subluxations to high dislocations secondary to developmental dysplasia of the hip. Periosteal and canal bony contours were extracted, 3 dimensional models generated, and morphologic parameters were calculated for each femur. Three dimensional illustrations of the average deformity and variability were created. Morphologic parameters were not found to be statistically correlated with the degree of the disease. Interestingly, the major axis of the canal contours of the proximal femur was found to be aligned with the plane of the femoral neck (anteversion), regardless of the degree of anteversion. Thus, the amount of version correctable in an uncemented prosthesis is limited, and at times may require a special prosthesis, overreaming, undersizing and cementing, or an osteotomy. Additionally, the proximal medial curvature of the dysplastic femurs was straighter than that of normal femurs. This necessitated a corresponding reduction in the proximal medial curvature of a conventional uncemented prosthesis to match the medial curvature of the individual femur and the average developmentally dysplastic femur. This objective description of the developmentally dysplastic femur corroborates clinical observations, highlights some unrecognized findings, provides a rationale for planning reconstructions, and aids in the design of prostheses for adult patients with this deformity.

Calcium crystal deposition in the ligamentum flavum of the cervical spine.

This article reports eight patients who underwent posterior decompressive surgery for myeloradiculopathy caused by calcium crystal deposition in the ligamentum flavum of the cervical spine. All were women with an average age of 72 years and showed neurologic improvement postoperatively. Four patients had diabetes mellitus, and knee meniscus calcification on radiographs were noted in four patients. The ligamentum flavum of C5-6 and C6-7 were sites frequently involved. Crystallographic examination confirmed resected deposits as calcium pyrophosphate dihydrate crystal in all patients and additional hydroxyapatite crystal in two. Histology confirmed marked degeneration in elastic fibers about the calcium deposits. This pathologic condition is possibly spinal manifestation of systemic calcium crystal deposition disease.

Prosthetic knee Candida parapsilosis infection

We report a 77-year-old man who developed Candida parapsilosis infection following total knee arthroplasty. Knee joint effusion was noted 2 weeks after surgery, and repeated cultures of aspirated fluid established the diagnosis of Candida parapsilosis infection 4 weeks after surgery. Treatment consisted of debridement and lavage of the involved joint together with continuous irrigation with fluconazole for 4 weeks, followed by oral fluconazole for another 6 months. At 3 years follow-up, the patient was doing well and radiological examination of the affected knee showed a firm attachment of the prosthesis. We suggest that early identification of the causative organism followed by continuous irrigation and use of appropriate antifungal medication may prevent joint instability and spares the removal of the prosthesis.

Histological investigation of spinal cord lesions in the spinal hyperostotic mouse (twy/twy): morphological changes in anterior horn cells and immunoreactivity to neurotropic factors.

Abstract We examined the morphology of spinal accessory motoneurons and immunoreactivity to neurotrophins, brain-derived neurotropic factor (BDNF) and neurotrophin (NT)-3, as well as the presence of reactive astrocytosis in 70 tiptoe walking Yoshimura (twy) mice that develop calcification at C1-C2 vertebral level compressing the spinal cord. At the level of compression, the area of neuronal soma and total length of dendrites of wheat germ agglutinin-horseradish peroxidase (WGA-HRP)-labelled accessory motoneurons in the medial cell pool decreased significantly with decrement in motoneuron population, relative to the control. In contrast, at sites rostral to the compressive lesion, a significant enlargement of the neuron soma and dendritic elongation were noted, associated with increased motoneuron population and decreased transverse area of the cord at the level of compression. At this site, enhanced BDNF and NT-3 immunoreactivities were evident in the anterior horn cells. In mice with a more severe degree of compression, astrocyte-like cells showing BDNF immunoreactivity became abundant and axons in the anterior column demonstrated a marked NT-3 immunoreactivity. Our results suggest increased functional activity of anterior horn cells at levels rostral to the site of compression. We speculate that the presence of BDNF and NT-3 in neurons and astrocyte-like cells is proportionate to the severity of chronic mechanical compression and may contribute to the heterotropic neuronal reserve and survival.

Quantitative analysis of the spinal cord motoneuron under chronic compression: an experimental observation in the mouse.

We investigated quantitative changes in spinal cord motoneurons following chronic compression using a mouse model of cervical cord compression. Twenty-five tiptoe-walking Yoshimura (twy) mice with calcified mass lesions compressing the spinal cord posterolaterally at the C1–C2 vertebral levels were compared with five Institute of Cancer Research (ICR) mice that served as controls. Spinal cord motoneurons in the anterior grey horn between the C1 and C3 spinal cord segments were Nissl-stained and counted topographically and then analysed in relation to the extent of spinal cord compression. The number of motoneurons in C1–C3 spinal cord segments decreased significantly with a linear correlation with the transverse area of the spinal cord when the cord was compressed to 50–70% of control values. A significant reduction in the number of motoneurons occurred at the C2–C3 spinal cord segment compressed at the C1–C2 vertebral level. In contrast, at the level rostral to the C1 vertebra, the number of motoneurons increased significantly in proportion to the magnitude of compression. The current study demonstrates that a number of neurons, morphologically consistent with anterior horn cells, were observed at a rostral site absolutely free of external compression where no such cells normally exist.

Visualization of the cervical spinal cord with FDG and high-resolution PET.

PURPOSE Our aim was to evaluate the visibility of the cervical spinal cord with [18F]2-fluoro-2-deoxyglucose (FDG) and a high-resolution PET scanner and to quantify the glucose utilization by the cervical cord. METHOD Twenty-one normal subjects and three cervical myelopathy patients were studied. The visibility of the cervical spinal cord in sagittal and coronal sections was evaluated. The metabolic rate of glucose (MRGlu) and standardized uptake value (SUV) of FDG in the cord were calculated. RESULTS The entire cervical spinal cord was clearly visualized in 57% of the subjects: the upper cord in 81%, the middle cord in 73%, and the lower cord in 57%. The MRGlu of the normal cord was 1.93 +/- 0.37 mg/100 g/min. SUV was constant across all the vertebral levels and negatively correlated with subject age. In the myelopathy patients, the SUV of the entire cervical cord was lower than in the age-matched normal subjects. CONCLUSION These preliminary results indicate that the cervical spinal cord can be visualized as a normal structure in routine head and neck PET imaging and that FDG-PET may provide quantitative information about spinal cord disorders.