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K Ohzono

Publications and source records attributed to K Ohzono.

At least 37 records · Page 2Linked to original sources
PubMed2000

Evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. The influence of the extent of porous coating.

BACKGROUND: Total hip arthroplasty changes the levels of stress within the proximal part of the femur, and the femur remodels adjacent to the prosthesis. The stem size and the initial bone-mineral density around the distal portion of the stem affect postoperative bone-remodeling after the insertion of a fully porous-coated metal-cancellous prosthesis. The purpose of this study was to evaluate the influence of the extent of porous coating of this prosthesis on femoral bone-remodeling. METHODS: A longitudinal examination of sixty-one hips in fifty-four patients was performed. Thirty-one hips in twenty-seven patients with a fully porous-coated stem (Group A) and thirty hips in twenty-seven patients with a proximally porous-coated stem (Group B) were followed for twenty-four to thirty months. Periprosthetic bone-mineral density was measured with dual-energy x-ray absorptiometry at specific intervals after the operation. RESULTS: In both groups, the greatest loss of bone-mineral density, compared with the initial (three-week) value, was approximately 20 percent in zone 7 at twelve to eighteen months. In other zones, bone-remodeling appeared to cease by twelve months. At the last follow-up evaluation, the loss of bone-mineral density in the distal and middle regions in Group A was significantly greater than that in Group B (p < 0.01 for zone 3 and p < 0.05 for zone 6). In contrast, with the numbers available, there were no significant differences in loss of bone-mineral density in the proximal regions (zones 1 and 7) between the two groups at any follow-up period. CONCLUSIONS: The extent of porous coating affects bone-remodeling in the distal periprosthetic region rather than in the proximal region. The results in the present report are specific to the particular implants that were studied.

Absorptiometry, Photon↗
PubMed1999

Contrast-enhanced magnetic resonance imaging in a nontraumatic rabbit osteonecrosis model.

We investigated early osteonecrosis using in vivo magnetic resonance imaging in a nontraumatic rabbit model of serum-sickness osteonecrosis in which osteonecrosis was induced after two intravenous injections of horse serum with a 3-week interval. One week (group A, 17 rabbits) and 3 weeks (group B, 13 rabbits) after the second serum injection, coronal magnetic resonance images of the femur were obtained and it was removed for histological study. Some of the necrotic lesions in the diaphysis were detected on T1-weighted, T2-weighted, or fat-suppression T1-weighted images (six of 24 necrotic lesions in group A and 16 of 18 in group B), and all of the necrotic lesions in the epiphysis, metaphysis, and diaphysis were detected on T1-weighted or fat-suppression T1-weighted images enhanced with gadolinium-diethylene triamine pentaacetic acid. All focal homogeneous enhanced areas on T1-weighted or fat suppression T1-weighted images corresponded to necrotic lesions (22 of 24 necrotic lesions in group A and 18 of 18 in group B); the contours of the enhanced areas were displayed more clearly on the fat-suppression T1-weighted than on the T1-weighted images. The fat-suppression T1-weighted image enhanced with gadolinium-diethylene triamine pentaacetic acid was thus the most sensitive and specific of five kinds of magnetic resonance images for the detection of early necrotic lesions. The results suggest that this image may be useful for early diagnosis of clinical osteonecrosis and for obtaining information about the pathomechanism of osteonecrosis.

Animals↗
PubMed1999

Stem length and canal filling in uncemented custom-made total hip arthroplasty.

We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio.

Adult↗
PubMed1999

Establishment of nurse-like stromal cells from bone marrow of patients with rheumatoid arthritis: indication of characteristic bone marrow microenvironment in patients with rheumatoid arthritis.

OBJECTIVE: To investigate the microenvironment of bone marrow (BM) of patients with rheumatoid arthritis (RA). METHODS: Nurse cell-like BM stromal cell lines were established from BM mononuclear cells of patients with RA. We examined the various characteristics of these cell lines, including morphology, pseudoemperipolesis activity, cell surface markers, cytokine production and hyaluronan (HA) production. RESULTS: These RA BM nurse cell-like lines (RA-BMNC) were of mesenchymal origin and positive for CD44, CD54 and HLA-DR. They were defined as nurse cells because of pseudoemperipolesis activity that allowed lymphocytes to migrate underneath. RA-BMNC lines produced HA and multiple cytokines including interleukin (IL)-6, IL-7, IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF). HA production by BM stromal cells was correlated with pseudoemperipolesis activity. RA-BMNC produced significantly higher levels of IL-6, IL-8 and GM-CSF by co-culture with lymphocytes. The cells also produced IL-1beta, G-CSF and tumour necrosis factor only when co-cultured with lymphocytes. The RA-BMNC maintained the growth of CD14+ myeloid cells unique to severe RA. CONCLUSION: The present results both indicate that RA-BMNC are nurse cells and suggest that they may play an important role in the pathogenesis of RA.

Antigens, CD↗
PubMed1999

Diagnostic criteria for non-traumatic osteonecrosis of the femoral head. A multicentre study.

Six major and seven minor diagnostic criteria have been developed by the Japanese Investigation Committee for osteonecrosis of the femoral head (ONFH). We have carried out a multicentre study to clarify these. We studied prospectively 277 hips in 222 patients, from six hospitals, who had ONFH and other hip pathology and from whom histological material was available. We identified five criteria with high specificity: 1) collapse of the femoral head without narrowing of the joint space or acetabular abnormality on radiographs, including the crescent sign; 2) demarcating sclerosis in the femoral head without narrowing or acetabular abnormality; 3) a 'cold-in-hot' appearance on the bone scan; 4) a low-intensity band on T1-weighted images (band pattern); and 5) evidence of trabecular and marrow necrosis on histological examination. With any combination of two of these criteria, the sensitivity and specificity of the diagnosis were 91% and 99%, respectively.

Adolescent↗
PubMed1998

Computed-tomography-based computer preoperative planning for total hip arthroplasty.

For precise preoperative planning in total hip arthroplasty (THA), we developed a technique of computed tomography (CT)-based computer preoperative planning and compared this technique with the single X-ray and template method generally used. The subjects of this study were 42 hips in 38 patients who underwent THA using a cementless total hip system. Preoperatively, a standard anteroposterior X-ray of the hip was taken, and conventional preoperative planning was done with a template of the total hip system. Transverse images were obtained using a helical CT scanner, and a CT-based computer preoperative plan was performed on true coronal slice images of the proximal femur reconstructed from CT data. Postoperatively, 29 hips (69%) showed good proximal fit of the femoral component to the medial endosteal line. Of the 20 hips with good proximal fit on preoperative X-ray planning, 12 hips had good proximal fit on postoperative X rays. Sensitivity and specificity of the proximal fit on X-ray templating were 41 and 23%, respectively. In 27 of 28 hips with good proximal fit on reconstructed CT images preoperatively, the postoperative X ray revealed good proximal fit. Sensitivity and specificity of the proximal fit on computer planning were 93 and 86%, respectively. Twelve hips with good proximal fit on preoperative templating, the reconstructed images, and the postoperative X ray had 20 degrees or less of combined femoral neck anteversion and external rotational contracture of the hip on the X-ray table. Eight hips with good proximal fit on preoperative templating and proximal poor fit on the reconstructed images had 17-65 degrees of combined version and rotational contracture. In 16 hips with poor proximal fit on preoperative templating and good proximal fit on the reconstructed images, the combined version and rotational contracture ranged from 17 to 69 degrees. When combined femoral neck anteversion and external rotational contracture of the hip is less than 15 degrees, the simple X-ray and template method might be sufficient for THA planning. Otherwise, the CT-based method of preoperative planning is recommended.

Arthroplasty, Replacement, Hip↗
PubMed1998

Articular cartilage evaluation in osteoarthritis of the hip with MR imaging under continuous leg traction.

We conducted MR evaluations of acetabular and femoral cartilages in 27 hips of patients with osteoarthritis and 10 hips of normal volunteers by a fat-suppressed three-dimensional (3D) pulse sequence using a continuous leg traction method, and correlated the results with radiographic assessment. Normal condition of the acetabular and femoral cartilages was clearly demonstrated in the normal volunteers. Grading of abnormalities was possible for each cartilage in the patients with osteoarthritis. In early osteoarthritis graded by radiography, a high prevalence of abnormalities was detected in the acetabular cartilage as compared with the femoral cartilage. Despite the structural difficulty in evaluation of the hip joint cartilage, our MR imaging technique can provide information concerning a wide spectrum of cartilage abnormalities even in the identical radiographic stage, which will lead to improvement in the evaluation of disease progression and in surgical planning.

Adult↗
PubMed1998

The Metal-Cancellous Cementless Lübeck total hip arthroplasty. Five-to-nine-year results.

We implanted 51 Metal-Cancellous Cementless Lübeck (MCCL) prostheses into 45 patients with dysplastic hips and followed 49 hips (96.1%) for five to nine years. One had needed revision for stem fracture and one for infection; the clinical outcome of the other 47 hips was assessed using the Merle d'Aubigné and Postel hip score. All hips were either excellent (63%) or good (37%). Three patients (6%) had mild thigh pain at six months, but this had settled within two years. Serial radiographs showed stable fixation with bone ingrowth in all hips, with increased density of the cancellous bone in contact with the implant and some trabecular ingrowth. There was early varus shift of the stem in one hip, but this stabilised in three months. Osteolysis of the femoral cortex was seen in one hip at seven years after surgery, and mild bone resorption due to stress shielding in 31 (63%). Acetabular bone grafting with autogenous bone from the femoral head gave successful support to the socket in 13 hips. The MCCL prosthesis gave satisfactory mid-term results in patients with osteoarthritis secondary to hip dysplasia.

Acetabulum↗
PubMed1998

MRI evaluation of steroid- or alcohol-related osteonecrosis of the femoral condyle.

We reviewed 30 patients (46 knees) with steroid- or alcohol-related osteonecrosis of the femoral condyle. Their average age was 35 (14-61) years and the mean observation time was 7 (3-16) years. The medio-lateral extent and the anterior-posterior (AP) location of the necrotic lesion were evaluated on T1-weighted MRI and related to the collapse of the condyle. The size of the lesion was classified into three categories on the mid-coronal MRI of the femoral condyle: there were 44 small, 20 medium, and 9 large lesions. The condyle was divided into 3 zones: anterior, middle, and posterior. The location of the lesion was evaluated on the mid-sagittal image. There were 7 anterior, 9 middle, 29 posterior, 14 middle and posterior and, in 14 cases, all 3 zones were involved. 44 small lesions did not collapse, while 6/20 medium lesions and 5/9 large lesions collapsed. No lesion involving only one zone collapsed, while 4/14 lesions involving the middle and posterior zones and 7/14 lesions involving all three zones progressed to collapse. 4/6 condyles with large necrotic lesions involving all three zones collapsed. We conclude that the extent of the necrotic lesion on both the mid-coronal and mid-sagittal planes is of importance for the prognosis of osteonecrosis of the femoral condyle.

Adolescent↗
PubMed1998

[The Osaka concept. "Dome osteotomy" with of without labrum resection].

Acetabular dysplasia represents the most common aetiology for secondary osteoarthritis of the hip joint in Japan. On radiographs progress of the disease can be classified in four stages (I to IV). Labral lesions are common accompanying findings in acetabular dysplasia, representing an important prognostic factor. Therefore we routinely use conventional arthrography to classify labral lesions in three types (normal, torn and detached). From 1978 to 1983 a modified Chiari osteotomy of the pelvis (dome osteotomy) was performed in 64 hip joints without arthrotomy. The preoperative radiography showed labral lesions in 66%. After an average follow-up of 4 years, 43 of the 44 patients with a normal or torn labrum showed excellent or good results. On contrast, 50% of the 20 patients with a detached labrum showed fair and poor results only. From 1984 to 1989 an arthrotomy was combined with dome osteotomy in 29 hip joints and labral lesions had to be resected in 16 cases. The results were generally good in patients with arthrosis grade I and II, but in stage III they were only fair. Thus, the success of labral surgery can only be achieved in early stages of dysplasia. Based on our findings dome osteotomy combined with arthrotomy and labral surgery can be recommended in patients with labral lesions and hip dysplasia grade I and II.

Acetabulum↗
PubMed1997

Acetabular osteolysis and migration in bipolar arthroplasty of the hip: five- to 13-year follow-up study.

We have reviewed 65 bipolar arthroplasties of the hip in 55 patients with osteoarthritis secondary to dysplasia. The mean age at operation was 56 years (42 to 79) and the mean period of follow-up was 7.2 years (5.0 to 13.0). The average Merle d'Aubigné and Postel score before operation was 10.3 and at final follow-up 15.0. There were excellent or good results in 42 hips (65%). Migration of the outer head was observed in 50 hips (77%), most often in the group with a centre-edge angle of less than 0 degrees, an acetabular head index of less than 60%, coverage of the outer head by the original acetabulum of less than +10 degrees and after bone grafting of the acetabulum. This migration was progressive in 31 (62%) of the 50 hips, with massive osteolysis of the acetabulum in eight. The extent and progression of migration were closely associated with this osteolysis. Four hips required revision for extensive migration of the outer head with destruction of the acetabulum or severe acetabular osteolysis, and nine hips are awaiting revision for failure of the bipolar prosthetic head. The overall failure rate was 18%. We report major problems after bipolar hip arthroplasty for osteoarthritis secondary to hip dysplasia with progressive migration of the outer head and massive acetabular osteolysis at five years or more after operation.

Acetabulum↗
PubMed1996

Inducible osteonecrosis in a rabbit serum sickness model: deposition of immune complexes in bone marrow.

We established inducible osteonecrosis in a rabbit serum sickness model. Osteonecrosis with marrow necrosis could be induced by the intravenous injection of horse serum in two doses separated in time by a period of three weeks. In this model, osteonecrosis could be successfully produced in rabbit femoral metaphysis. The incidence of marrow necrosis was 45% (9 of 20 rabbits) and trabecular necrosis occurred in 6 of 20 rabbits (30%) at 7 days after the second injection of the horse serum. In bone marrow of the femoral metaphysis, extravasation of erythrocytes and the formation of micro-thrombi in arterioles were often observed in an early stage of the present model and both findings correlate well each other (p = 0.0001). Immune complexes could be demonstrated using immunohistochemistry in bone marrow of the femoral metaphysis as well as in glomeruli of the kidney. Extravasation of erythrocytes in bone marrow of the femoral metaphysis was observed in 8 of 12 (67%) cases with immune complex deposition in the sinusoidal space of the femoral metaphysis and in 12 of 21 (57%) cases with immune complex deposition in glomeruli of the kidney. Immune complex deposition both in the sinusoidal space of femoral bone marrow (p = 0.0385) and in glomeruli of the kidney (p = 0.0209) closely related to extravasation of erythrocytes and microthrombi in arterioles in the early stage of this model. Early microcirculatory injury (extravasation of erythrocytes and microthrombi in arterioles) adjacent to osteonecrosis could be induced by immune complex deposition in femoral bone marrow and might be predictable characteristics for the inducible osteonecrosis in the present serum sickness model. The important findings in this study were that early microcirculatory injury was closely related to the deposition of immune complexes in femoral bone marrow, and that early microcirculatory injury associated with immune complex deposition was located close to osteonecrotic regions.

Animals↗
PubMed1996

Bone scintigraphy as an indicator for dome osteotomy of the pelvis: comparison between scintigraphy, radiography and outcome in 57 hips.

We performed dome pelvic osteotomy in 57 hips (54 patients) because of acetabular dysplasia. All patients had preoperative scintigraphy and were followed for more than 2 years. Excellent or good results were obtained in 49 hips, but 8 hips deteriorated. All hips which deteriorated had preoperatively a spotty isotope uptake image localized to the weight bearing area and the medial area of the joint. No hip without this image deteriorated, even when preoperative radiography showed advanced arthrosis. Our findings indicate that bone scintigraphy may be a more reliable predictor of failure for this operation than radiography.

Adolescent↗
PubMed1995

The immune reaction to heterologous serum causes osteonecrosis in rabbits.

Osteonecrosis (ON) was produced experimentally in rabbits by intravenous injection of horse serum. Eighty adult rabbits were used: 16 were injected twice with isotonic saline (Group A), 24 were injected once with saline and once with horse serum (Group B), and 40 were injected twice with horse serum (Group C). Both femurs of each rabbit were obtained from 2 h to 7 weeks after the final injection an were subjected to histological examination. No pathological changes were seen in Groups A and B. In Group C, 5 of 15 rabbits (33%) showed ON (necrosis of trabecula and bone marrow) in the femoral metaphysis. In Group C, the early major pathological findings in bone marrow are extravasation of erythrocytes in sinusoidal spaces and microthrombi in small arteries and arterioles near the lesion of extravasation. Immune complexes were demonstrated in the kidney within 24 h of the final injection of horse serum. The present study suggests that immunological reaction associated with serum sickness may play an important role in inducible ON and this model will contribute toward clarifying the pathogenesis of ON.

Animals↗
PubMed1994

Serial change of sliding in intertrochanteric femoral fractures treated with sliding screw system.

We investigated the serial change of the extent of sliding of the compression screw in 42 intertrochanteric femoral fractures fixed with a sliding screw system. Neither age, gender, bone density, fracture type nor quality of fracture reduction could accurately predict healing time. There was a significant correlation between the extent of sliding at union and healing time (correlation coefficient r = 0.505). The average healing time in group B (the extent of sliding at union of 8 mm or greater) was 13.8 weeks postoperatively, and that in group A (the extent of sliding at union of less than 8 mm) was 8.9 weeks. There was a significant difference in the average healing time between groups A and B (P = 0.0004). The extent of sliding at union had a influence on the healing time. The phenomenon of sliding progressed mainly during the first 2 weeks postoperatively. There was a significant positive correlation between the extent of sliding at union and the extent of sliding at 2 weeks postoperatively (r = 0.977). An assessment using the extent of sliding at 2 weeks postoperatively can accurately predict the extent of sliding at union and the healing time. It is important to examine the phenomenon of sliding during the early postoperative course, especially until 2 weeks postoperatively, in order to predict fracture repair.

Age Factors↗
PubMed1994

Spongy metal Lübeck hip prostheses for osteoarthritis secondary to hip dysplasia. A 2-6-year follow-up study.

Between May 1987 and December 1990, 66 hips in 59 patients with osteoarthritis secondary to hip dysplasia underwent cementless total hip arthroplasty with a spongy metal Lübeck hip prosthesis (S+G Implants, Lübeck, Germany) that had a fully porous-surfaced short stem made of cased cobalt-chrome-molybdenum alloy. Sixty-five hips in 58 patients were prospectively followed for 2-6 years (mean, 43 months). Patient age at operation ranged from 29 to 63 years (mean, 51 years). The Merle d'Aubigné hip score improved from 7.8 before surgery to 16.9 at the final follow-up evaluation. All hips were rated as either excellent (63%) or good (37%). Mild thigh pain was recognized in only three hips (5%) at 6 months after surgery, but it disappeared within 2 years. Serial roentgenograms showed stable fixation with bone ingrowth in all hips, that is, bone densification in contact with the implant and trabecular connection to the endosteal surface. The authors found no migration of the implant or circumferential radiolucency. Moderate osteopenia, presumably due to stress shielding, was seen in only four hips (6%). Acetabular bone-grafting performed in 31 hips gave successful support to the socket. Cancellous bone chips grafted to small defects showed excellent remodeling. The authors conclude that the spongy metal Lübeck hip prosthesis contributed to lower rates of thigh pain and migration than cementless prostheses.

Adult↗
PubMed1994

Progressive migration in bipolar arthroplasty for osteoarthritis of the hip secondary to congenital dislocation.

Seventy-one hips with osteoarthritis secondary to congenital dislocation underwent bipolar arthroplasty with autologous bone grafting (grafted group) or without bone grafting (ungrafted group). Clinical and radiographic followup was performed; the average followup was 5.7 years (range, 3-11.3 years). At followup, the mean Merle d'Aubigné and Postel score was 14.3 points. Excellent or good results were achieved in only 50% of all cases. The mean extent of prosthetic head migration was 6.5 mm in the grafted group and 4.7 mm in the ungrafted group. Progressive migration occurred in 68% of the grafted group and in 43% of the ungrafted group. There was a significant negative correlation between the extent of migration of the outer head and the coverage of the outer head by the original acetabulum (R = 0.53). In the grafted group, the revision rate for failure of the outer head of the prosthesis was 60% at 6 years postoperatively. In the grafted group, progressive migration was more extensive and more frequently than in the ungrafted group. Extensive migration was also observed when there was adequate coverage of the outer head by host bone in the ungrafted group. In conclusion, bipolar arthroplasty is not recommended for osteoarthritis secondary to congenital hip dislocation because of the poor clinical outcome, high risk of significant progressive migration, and high revision rate.

Adult↗