The design characteristic of the Osteonics total knee is the high conformity of tibiofemoral articulation on the coronal plane. Primary total knee arthroplasty using Osteonics (Omnifit/Deltafit) total knee system was performed in 56 patients (78 knees). Of these, 45 patients (58 knees) were evaluated at least 5 years. The varus-valgus stress test was performed at 20° of knee flexion using a digital instrument. In 40 patients (50 knees), we measured the tibiofemoral contact point on the sagittal plane under weight-bearing conditions. At the latest follow-up, 8 knees were rated as excellent, 38 knees as good, and 12 knees as fair, using our rating system. There was no loosening, osteolysis, or apparent polyethylene wear on plain radiographs. Varus-valgus instability of the knee was significantly reduced after total knee arthroplasty compared with the control value. However, tibiofemoral motion on the sagittal plane was significantly different from that of the normal knee, especially in the posterior cruciate sparing knees. Based on our results, we suggest that a long-term follow-up is necessary to establish whether the Osteonics total knee system truly reduces polyethylene wear.

We report eight patients with a solitary plasmacytoma of the spine associated with neurological complications. The patients included five men and three women with an average age at presentation of 59 years (range, 47 to 73 years). The tumour was confined to the thoracic spine in six cases, cervical spine in one and lumbar spine in one. Duration of symptoms ranged from 2.5 to 22 months. Treatment consisted of a combination of radiotherapy, melphalan and surgery. One patient progressed to multiple myeloma 7 years after surgery. Surgical treatment (anterior surgery in three cases and posterior surgery in five) produced neurological improvement in all patients. We stress the importance of an early diagnosis followed by appropriate treatment including surgery for this clinical entity and long-term follow-up to detect a disseminated disease.

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.

Laser confocal microscopy isa powerful tool for histochemical nd cytochemical studies. It enables us to detect the fluorescencelabeled molecules in the specimens by optical. Simultaneous staining of nuclei with appropriate fluorescent dyes as counterstaining greatly facilitates the identification f the localization ofthe label. Recently, a variety of nucleic acid binding fluorescent dyes have been developed. We screened 20 nucleic acid-specific dyes for use in nuclear staining in laser confocal microscopy with Kr/Ar laser. Results were evaluated in 1) fluorescent intensity, 2)DNA specificity, and 3)bleaching characteristics. Among green fluorochromes xcited at 488 nm, YO-PRO-1, SYTOX Green, and SYBR Green l were suitable for nuclear DNA staining. Among red fluorochromes xcited at 568 nm, propidium iodide stained nuclear DNA with simultaneous staining of cytoplasmic and nucleolar RNAs. Among far-red fluorochromes xcited at 647 nm,TO-PRO-3 was specific for DNA, whereas TOTO-3 strongly co-stained cytoplasmic and nucleolar RNAs. Bleaching by laser illumination was retarded by mounting with media containing and-bleaching reagents such as DABCO and PPDA. Nuclear staining fluorescent dyes should be selected by comparing these characteristics.

The fit and fill of the femoral canal are critical to the success of cementless femoral stems in total hip arthroplasty. It is difficult for conventional stems to provide a good fit and fill for the femora of patients with secondary osteoarthritis. Based on measurements of 100 femora of these patients, we designed two types of Fukui Medical School (FMS) stems with a proximal lateral flare that differed in the medial radius. We compared the fit and fill of the FMS stems with those of four conventional stems, using computer simulation. The mean proximal fit and total fit of the FMS stems were 46% and 53% respectively, a significant improvement compared with the other stems examined. The mean fill of FMS stems was 82% at the lower end of the lesser trochanter and 84% at the upper end of the isthmus, values that were significantly higher than those of the other stems. Since September 1995, we have implanted FMS stems in 15 hips with secondary osteoarthritis. Radiographic evaluations showed that the canal fill of the FMS stems was significantly greater in the proximal femur compared with other stems previously inserted at our department.

We investigated the effect of chronic mechanical compression of the cervical spinal cord on the number of spinal accessory motoneurons in 25 tiptoe-walking Yoshimura mice. The animals had calcified deposits in the atlantoaxial membrane at the C1-C2 vertebral level, compressing the spinal cord posterolaterally. Motoneurons of the spinal accessory nerve between C1 and C5 segments were labelled using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injected into the sternocleidomastoid muscles. The counted cells were processed into a three-dimensional computer display to analyse the cytoarchitectonic changes caused by external cord compression. The number of WGA-HRP-labelled spinal accessory motoneurons was significantly reduced on the affected side. The number of motoneurons in compromised C2 and C3 cord segments correlated linearly with the extent of mechanical compression, but no such relationship was present on the contralateral side. There was an increase in the number of WGA-HRP-labelled spinal accessory motoneurons in the medial cell pools of the anterior grey horn at a level most rostral to the compression, and in the ventrolateral cell pools at levels immediately rostral to the compression. Our findings suggest that the spinal accessory motoneurons translocate rostral to the area of external compression in order to avoid mechanical injury.

To investigate the relationship between morphological plasticity of the spinal cord and neurological outcome after surgery for compressive lesions, we correlated the transverse area of the cervical spinal cord measured by transaxial magnetic resonance imaging (MRI) obtained during the early postoperative period (1–6 months) with neurological function assessed at a median postoperative follow-up period of 2.5 years. Measurements on MRI in 56 patients (35 men and 21 women) included evaluation of the cross-sectional area of the cervical cord and the subarachnoidal space at the level of decompression. The transverse area of the cervical cord increased by 30 to 62% postoperatively and that of the subarachnoidal space by 57 to 95%. Neurological improvement was noted in all patients and averaged 63% in our assessment scale. Expansion of the cervical cord during the early postoperative period correlated significantly with the late postoperative neurological status (P = 0.009). Our results suggest that an increase in the cross-sectional area of the cervical spinal cord, representing spinal cord morphological plasticity, is a significant factor in determining the late neurological improvement following decompressive surgery.

We describe a man aged 26 years who presented with a neurological syndrome, which was found on lumbar radioculopathy to be due to a ganglion cyst originating from the posterior longitudinal ligament. Based on MRI findings, a cystic lesion was suspected, a round lesion at L4 level with no connection to the adjacent facet or to the dura matter. During surgery, a liquid-containing cystic lesion was found to originate from the posterior longitudinal ligament at L4 level. The resected cyst was diagnosed histologically as a ganglion cyst. A complete cure was established after surgery and no recurrence was noted at a follow-up 1.7 years postoperatively. A ganglion cyst of the posterior longitudinal ligament should be considered in the differential diagnosis of a cyst in the lumbar region causing neurological complications.

We evaluated the use of three-dimensional (spiral) computed tomography (CT) to assess widening of the bony cervical spinal canal following en bloc open-door C3 – C7 laminoplasty in 31 patients. Measurements were performed using a computerised image processing system. The increment in the anteroposterior spinal canal axis and volume of the bony spinal canal was investigated in relation to changes in cervical spine lordosis as well as postoperative neurological improvement. Neurological follow-up averaged 2.6 years (range, 1 to 7 years). A mean increase of 42% was observed in the anteroposterior axis of the canal between C3 to C7 after surgery, while the volume increased by 45%. Postoperatively, cervical spine lordosis correlated with increments in the volume of the enlarged bony canal rather than the anteroposterior axis. Postoperative neurological improvement correlated significantly with the increase in the canal volume. Our results indicate that spiral CT is useful for the assessment of the magnitude of cervical canal enlargement and evaluating the space available for the spinal cord following the relief of compression.

本研究の目的は，スクワット動作の定量化をもとにした前十字靱帯再建術後プログラムを実施した症例の筋力改善効果を示すことである。最初に定量化を目的に前十字靱帯再建術後患者2例でモデル解析をおこない，スクワット動作時の膝関節伸展トルク値を計測した。それをもとにスクワット動作を主とした閉鎖性運動連鎖による訓練を前十字靱帯再建術後プログラムに難易度を考慮し段階的に取り入れ17例に実施し，従来の等速度訓練を中心とした開放性運動連鎖による訓練によるプログラムを実施した11例と比較した。術後約1年でみた筋力は，CKC ex.群で受傷側・非受傷側の伸展・屈曲共有意に改善しており，閉鎖性運動連鎖による訓練を中心とした新しいプログラムは有効と考えられた。

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.

Spinal cord evoked potentials (SCEPs) were recorded epidurally in 95 surgical cases of cervical and/or thoracic compressive myelopathy. Abnormal SCEPs occurred in 91% of the patients with cervical myelopathy and in all with thoracic involvement at the levels suspected to be responsible for neurological damage. Abnormal SCEPs correlated significantly with the severity of spinal cord compromise and symptoms, such as myelopathy. It was not possible to predict postoperative neurological improvement on the basis of the preoperative SCEP findings alone, but better neurological improvement after surgery was closely associated with early recovery of intra- and postoperative SCEPs. Epidural SCEPs are therefore useful in making a level-specific diagnosis, especially in the patient with multilevel vertebral involvement, and in assessing the severity of neurological compromise and surgical outcome to some extent.

We investigated quantitative changes in spinal cord motoneurons following chronic compression using a mouse model of cervical cord compression. Twenty-five tip-toe-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.

Our report concerns five patients who underwent lumbar decompressive surgery for cauda equina syndrome and radiculopathy secondary to degenerative stenosis associated with calcium deposition in the ligamentum flavum. The resected ligamentum flavum showed diffuse to massive calcium crystal deposition with a histologically marked degeneration in the elastic fibres. Energy dispensive radiographic microanalysis confirmed the crystal to be calcium pyrophosphate dihydrate in all patients, hydroxyapatite mixed in three and calcium orthophosphate mixed in one. The deposition appeared to be a change that is associated with the degenerative process in the ligament and, in some cases having marked deposition in a localised event, it causes or aggravates the neurological symptoms.

Cervical laminoplasty was the operation used for myeloradiculopathy secondary to ossification of the posterior longitudinal ligaments. Some 57 patients were followed up for 5-13 years (average: 7.8 years). The spinal canal from C3 to C7 was surgically opened en bloc unilaterally with spacer bone grafting to maintain the laminae in a 'kept open' position and thus to implement posterior decompression. No serious major surgery-related complications were observed. Favourable results were obtained in 42 patients (74%), but those with advanced preoperative neurological symptoms did not improve. Patients with spinal canals seriously compromised by anterior ossified lesions recovered poorly. We concluded that laminoplasty is recommended for cervical myeloradiculopathy due to ossified posterior longitudinal ligaments for selected patients, but surgery should be done before the patient has developed serious neurological damage.