Kohtaro Furuya

The natural history of herniated nucleus pulposus with radiculopathy.

Study Design The present study retrospectively investigated the morphologic changes that occurred during conservative treatment of patients with unilateral leg pain resulting from herniated nucleus pulposus without significant lumbar canal stenosis. Objectives The results were correlated with clinical outcomes and extruding forms to determine which type of herniated nucleus pulposus had the greatest capacity for spontaneous regression and how rapidly such regression might occur. Summary of Background Data The study population consisted of 77 patients with radiculopathy. All patients complained primarily of unilateral leg pain, and 94% had positive tension signs. Additionally, 32% exhibited muscle weakness corresponding to the symptomatic nerve root. Methods All patients were studied more than twice using magnetic resonance imaging during conservative therapy at a mean interval of 150 days. Morphologic changes on magnetic resonance imaging fell into four categories, with herniated nucleus pulposus classified into three types using T1-weighted sagittal views. Each patient was reexamined on the same scanner; 53 patients were examined twice, and 24 patients were examined more than three times. Results Morphologic changes, with the exception of 13 false-negative cases, basically corresponded to clinical outcome. In half of the cases that showed some improvement at follow-up evaluation, improvement of clinical findings were seen before those observed on magnetic resonance imaging. Migrating herniated nucleus pulposus frequently presented an obvious decrease in size, and even disappearance in seven cases. The further the herniated nucleus pulposus migrated, the more decrease in size could be observed. The cases apparently corresponding to “protrusion” showed little or no change on follow-up magnetic resonance imaging. Regarding the mechanism of herniated nucleus pulposus disappearance, exposure to the vascular supply undoubtedly took a part, although many factors were suspected to have some influence. Conclusion Morphologic changes on magnetic resonance imaging mainly corresponded to clinical outcomes but tended to lag behind improvement of leg pain. Disappearance of herniate nucleus pulposus was seen frequently in the cases of migrating disc herniation, and it was presumed that exposure to the vascular supply had a lot to do with this phenomenon.

Upregulated expression of chemokines in herniated nucleus pulposus resorption.

Study Design Immunohistologic examination was performed on surgically removed samples of herniated nucleus pulposus. Objectives To determine what cell types predominate in the granulation tissues of herniated nucleus pulposus, and to elucidate whether chemokines are involved in the resorption process of herniated nucleus pulposus. Summary of Background Data The study population consisted of 30 patients suffering from herniated nucleus pulposus. Five macroscopically normal discs were obtained from spinal cord tumor and spinal cord injury managed with anterior discectomy (age range, 27‐63 years) as a healthy control group. Methods Immunohistochemical analysis was used to analyze the expression of chemokines. Results A marked infiltration of macrophage and vascular proliferation was identified with a T lymphocyte infiltration of mild degree in the granulation tissues. This tendency was more prominent in the exposed group compared with the nonexposed group. Infiltrating macrophages, fibroblasts, and endothelial cells in the granulation tissues strongly expressed monocyte chemotactic protein‐1 and macrophage inflammatory protein‐1α. Statistical analysis demonstrated that the exposed group was more abundant in Factor VIII, monocyte chemotactic protein‐1, and macrophage inflammatory protein‐1α positive cells than the unexposed group. Conclusions Inflammatory cells and their positivity for chemokines, such as monocyte chemotactic protein‐1 and macrophage inflammatory protein‐1α, are associated with blood vessels. Chemokines, such as monocyte chemotactic protein‐1 and macrophage inflammatory protein‐1α, were overexpressed in macrophages, fibroblasts, and endothelial cells, suggesting that these chemokines contribute to activation and recruitment of macrophages in a paracrine or autocrine fashion.

The effects of tibial tunnel placement and roofplasty on reconstructed anterior cruciate ligament knees.

Seventy-five anterior cruciate ligament (ACL) reconstructions augmented with the Kennedy Ligament Augmentation Device were evaluated according to classification of tibial drill-hole position on the basis of the anatomic landmarks of the ACL by two-dimensional radiographic imaging of the fully extended knee. The effects of roofplasty to avoid graft impingement were also assessed. The tibial drill-hole position was classified in relation to the medial intercondylar tubercle on anterior-posterior (AP) view, and in relation to Blumensaats line (B-line) on lateral view. Arthroscopic evaluation of the ACL and incidence of chronic synovitis as well as Lysholm knee score, manual knee tests, knee extension and flexion angles, and knee tester measurements were performed. The results indicated that the knee joints in which the tibial drill hole was positioned laterally from the medial intercondylar tubercle or in which the tibial drill hole was positioned anteriorly to the B-line showed a tendency to develop more postoperative chronic synovitis. The knees in which the tibial drill hole was positioned anteriorly to the B-line also showed larger AP laxity. There was no difference between the non-roofplasty and roofplasty groups.

Computerized Tomographic Analysis of Tibial Tubercle Position in the Painful Female Patellofemoral Joint

We used computerized tomography to evaluate the po sition of the tibial tubercle and to determine if the tibial tubercle is positioned more laterally in female patients with patellofemoral pain. We also wanted to determine the relationship of the tibial tubercle to tibial external rotation and patellar tilt. Sixty female patients and 19 healthy female controls were evaluated. To evaluate the position of the tibial tubercle, the tibial tubercle rotation angle (the angle formed by the line between the pos teriormost edges of the medial and lateral femoral con dyle and the line between the central point of the in tercondylar space and the central point of the patellar tendon at the level of the tibial tubercle) was measured by superimposing the images from the level of the distal femoral condyle and the tibial tubercle. The relationship between the tibial tubercle rotation angle and patellar tilt was then assessed by dividing the patients into 3 sub groups according to the patellar tilt. The tibial tubercle rotation angle was significantly different between the patellofemoral pain patients and the controls. There were also significant differences between the patients with moderate patellar tilt (10° to 20°) and the controls, and between the patients with high patellar tilt (>20°) and the controls.

Performance of adhesive bone cement containing hydroxyapatite particles.

A new acrylic bone cement which can adhere to both bone and prostheses was developed based on a methyl methacrylate (MMA) monomer containing 4-methacryloyloxyethyl trimellitate anhydride (4-META) as adhesion promoting agent. Moreover, hydroxyapatite (HA) particles were introduced into the 4-META cement as a bone compatible filler. The mechanical strengths of an acrylic bone cement without 4-META decreased drastically with an increase in the percentage of HA particles in the cement. However, the mechanical strengths of the HA-containing 4-META cement did not change in the same way as that of the 4-META cement without HA due to adhesion between the cement HA particles and matrix. The HA particles did not affect the adhesion of the 4-META cement to bone and metals. Implantation of the 4-META cement and the HA-containing 4-META cement in animals demonstrated that these cements did not disturb bone ingrowth and the new bone was able to contact the cement directly. The 4-META cements, with and without HA particles, could adhere to bone in vivo.

Relationship between changes in length and force in in vitro reconstructed anterior cruciate ligament

The effect of tibial and femoral attachment site on the length change and force of an anterior cruciate ligament graft during unloaded flexion in eight cadaver speci mens was examined. Two tibial sites (anteromedial and central portion of the anterior cruciate ligament attach ment) and three femoral sites (anterior and central portions of the anterior cruciate ligament attachment, and over-the-top) were evaluated. Graft length changes between all combinations of attachment sites were measured from full extension to 150° of passive flexion at 15° intervals using the displacement of a 2-mm inextensible cord. The anterior cruciate ligament was then reconstructed using a Kennedy Ligament Aug mentation Device, and graft forces at the same angles of passive flexion were measured with a buckle trans ducer. Graft length change and force were more affected by the femoral attachment site than the tibial site. There was a close correlation between length change and force measurements in flexion, but not near extension. The pattern of force and length change versus flexion angle for a given combination of attachment sites some times varied over the knees tested. Our results suggest that intraoperative isometry measurements are worth while for indicating an overloaded graft in flexion; how ever, length changes near extension may not ade quately reflect graft force, creating the possibility that a graft may be more highly loaded than realized.

Immunohistologic analysis of synovium in infrapatellar fat pad after anterior cruciate ligament injury.

To clarify the natural course of synovitis after anterior cru ciate ligament injury, we took synovial tissues at various periods after injury and analyzed them immunohistologi cally. Twelve patients with isolated anterior cruciate liga ment injuries participated in the study. Inflammation in tensity was graded semiquantitatively based on the following parameters: synovial lining cell depth, synovial hyperplasia, vascular hyperplasia, lymphocyte infiltration, and the expression of cell adhesion molecules. The ex pression of fibrogenic cytokines and the degree of fibrosis were also investigated to elucidate the mechanisms of ar throfibrosis. The results demonstrated that synovitis in the infrapatellar fat pad subsides within 3 months after injury with the progression of fibrosis. Fibrogenic cytokines, platelet-derived growth factor and transforming growth factor-β, were detected at fibrotic sites, suggesting their involvement in arthrofibrosis. An increased incidence of arthrofibrosis recently has been recognized to occur when anterior cruciate ligament reconstruction is performed within several weeks after injury. We speculate that when anterior cruciate ligament reconstruction is performed dur ing the stage of acute synovitis, the operation may further promote the synovitis, accelerating the arthrofibrotic re action. Waiting to perform the anterior cruciate ligament reconstruction until the synovitis resolves may possibly decrease the motion problems seen postoperatively.

Quantitative Analysis of Synovial Fibrosis in the Infrapatellar Fat Pad Before and After Anterior Cruciate Ligament Reconstruction

We performed quantitative analysis of synovial fibrosis in the infrapatellar fat pad in 26 patients who under went arthroscopically assisted anterior cruciate liga ment reconstructions. Twelve patients underwent re construction with patellar tendon autografts, and 14 had reconstructions with semitendinosus and gracilis tendon autografts. Synovial samples were obtained at the time of reconstruction from 10 patients and at second-look arthroscopy from all 26 patients. Sections from quick-frozen samples were stained with either hematoxylin and eosin or Fast green and Sirius red. We used sodium hydroxide in absolute methanol to elute the Fast green and Sirius red stains, and the total collagen content of each section was estimated by measuring the optical density of the eluted solution. The volume of each section was determined on a computer using an imaging program, and collagen content per unit of tissue was calculated. Median col lagen content was 15.3 μg/mm3 for the preoperative samples, 25.1 μg/mm3 for the group with patellar ten don autografts, and 27.1 μg/mm 3 for the group with hamstring tendons autografts. Analysis of preoperative and postoperative paired samples revealed a signifi cant increase in synovial collagen after anterior cruci ate ligament reconstruction. We observed increased fibrosis in patients who had pain on exertion or stiff ness in squatting after the reconstructive surgery.

Forefoot pressures during walking in feet afflicted with hallux valgus

Forefoot pressures during walking in feet with hallux valgus were recorded using pressure-sensitive film, and the relationships between deformities and foot pressures were analyzed. There were 32 female subjects comprising 50 feet with hallux valgus, of which 20 feet underwent surgery. As in normal feet, the pressure patterns of feet with hallux valgus were varied: peak pressures were under the first metatarsal head, under the second and/or third metatarsal heads, and the first, second, and/or third metatarsal heads. Peak pressures of hallux valgus feet were larger in each type than those of the normal foot. In feet with hallux valgus showing peak pressures under the first metatarsal heads, the hallux valgus angle and the intermetatarsal angle were larger than those in feet showing peak pressures on the second and/or third metatarsal heads. After surgery, peak pressures were under the second and/or third metatarsal heads and they decreased.

A new method of multisegment motor pathway monitoring using muscle potentials after train spinal stimulation

Study Design. Evoked muscle and nerve action potentials after spinal stimulation for intraoperative monitoring were investigated using a modified stimulation technique. Animal experiments and clinical application were performed. Objectives. To contrive a useful method of intraoperative motor pathway monitoring under inhalation anesthesia. Summary of Background Data. Many different kinds of procedures have been reported. No reliable method that reflects pure motor tract function has been established. Methods. Characteristic of our stimulating technique was the use of numbered consecutive pulses (“train stimulation”). In 16 cats, optimum condition of train stimulation, effects of anesthetic agents, and conductive pathway were examined. In 35 patients, muscle potentials evoked by train stimulation were recorded, and clinical usefulness was evaluated. Results. In the experimental study, the optimum stimulus condition was determined 1 ms interstimulous interval train of five pulses. Conductive pathway of this method was identified as a lateral column by selective spinal cord transection, In the clinical application, by using train stimulation, multisegmental muscle potentials were obtainable even using inhalation anesthetics. Conclusions. The facilitative effects of train stimulation, attributed to temporal summation, are considered to overcome the suppression of inhalation anesthesia. The evoked muscle potentials by train spinal stimulation reflect the functions of pure motor tract and is the only, extremely efficient method for intraoperative motor pathway monitoring.