Introduction of the Ilizarov external fixator has bought about a treatment revolution to resolve such orthopaedic problems as fracture fixation, limb lengthening, deformity correction, joint mobilization, and reconstruction of bone and soft tissue defects. One of the advantages of the Ilizarov method is its versatility, that is, different orthopaedic problems can be simultaneously treated with the Ilizarov method. In this study, we introduce a method of deformity correction of the lower extremities and reconstruction of skeletal defects using the Ilizarov external fixator. Deformity correction with the Ilizarov hinge system is very useful to realign the mechanical axis of the lower extremities. We also introduce a new concept of high tibial osteotomy called“mechanical axis lateralization”for genu varum resulting from unicompartmental medial osteoarthrosis, Blount's disease and so on. In addition, the Ilizarov method made it possible to successfully reconstruct extensive bone defects combined with or without intramedullary nailing. The Ilizarov method will become more widely used and advantageous if the treatment period is shortened.

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The wear of polyethylene sockets in Muller and Bioceram type hip prostheses was determined by radiographic measurement. The study materials included 162 Müller prostheses with Cobalt-Chromium (Co-Cr) alloy femoral heads (32-mm diameter), and 68 Bioceram prostheses with alumina ceramic femoral heads (28-mm diameter) . The follow-up period was 10 years after replacement.
Annual linear wear rate was 0.098 and 0.121 mm/year in the Müller and Bioceram groups, respectively. There were no demographic factors that significantly affected polyethylene wear. In both the Müller and Bioceram groups, significantly higher wear was observed in the patients with greater bone resorption.
Alumina ceramic heads were not preferable to metallic heads in relation to the polyethylene wear. Factors affecting polyethylene wear do not seem to be related to the type of prosthetic head emnloved.

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We evaluated leg rotation and knee stability after ACL reconstruction (modified over-the-top method using patella tendon bone) using a three - dimensional analyzer. The study assessed 23 ACL reconstructed knees (10 male and 13 female patients) . Mean age at time of operation was 23.8 years. Leg rotation and knee stability were measured by Knee Motion Analyzer (CA 4000) pre-operatively and at 3, 6, 9, and 12 months post operatively. Qualitative evaluation of knee motion revealed 4 patterns of leg rotation. In Group 1 there was normal rotation of the leg (physiological screw home movement) . In Group 2 there was almost normal rotation but a decrease in external rotation at the end of knee extension. In Group 3 there was no external rotation. In Group 4 there was scarcely any rotation. Twelve cases (52.2%) were Group 4 at 6 months post-operatively. At 12 months, 18 cases (78.3%) were Group 1 and 2; only 4 cases were Group 4. We conclude that in ACL reconstructed knees establishment of stability in the AP dimension also leads to normal rotation of the leg.

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The clinical results of total knee arthroplasty (TKA) with an AXIOM system were examined in patients who remained under observation. The mean observation period was five years and one month. In our department, 94 joints in 59 patients constituted the subjects of the present study. There were 48 females and 11 males; average age at the time of operation was 64.3 years. As classified by disease, 43 joints in 27 patients were rheumatoid arthritis (RA), and 51 joints in 32 patients were osteoarthritis (OA) . The follow-up period ranged from three years and six months to six years and three months (mean five years and one month) . Our study focused on the pre- and post-operative JOA score, radiographic examinations, complications and related problems. At the time of examination, the post-operative JOA score was satisfactory and remained stable. No loosening or malalignment was detected on X-ray films after operation; no case required revision arthroplasty. As for complications, late infection occurred in one patient, patella dislocation in one, and patella subluxation in four. TKA with an AXIOM system was thus found to have yielded satisfactorily stable results.

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Insufficiency fracture occurs in a fragile bone as a result of minor trauma. Various names have been used to describe this condition. We report 5 cases of insufficiency fractures of the pubic bone. All patients were women, with ages ranging from 71 to 85 years (mean 76 years) . Four had rheumatoid arthritis and one had Parkinson's disease. We investigated the degree of trauma, clinical manifestations, and possible combined fractures. In all patients, initial plain radiographs showed no definite fracture line of the pubic bone. Osteolysis of the pubic bone was seen in 3 patients. Four patients had associated spinal compression fractures. Clinical manifestations were pain in the lower back, buttock, hip and thigh. It proved difficult to make diagnoses based on the initial plain radiographs. Follow-up radiographs, CT, MM and bone scintigraphy are useful for such diagnoses. Authors discussed this kind of fracture using nomenclature translated from the original Japanese text.

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We have reviewed the results of treating fifteen Ipsilateral femoral fractures after total hip arthroplasty (THA) and bipolar hemiarthroplasty (BHA) . Five men and 10 women were operat-ed on between November 1990 and November 1997. Age at the time of fracture ranged from 45 to 87 years (average, 65 years) . There were 7 THAs and 8 BHAs. Twelve femoral compo-nents were fixed with bone cement and 3 without cement. According to Johansson's classifica-tion, there were 6 type I fractures (proximal to the tip), 6 type II fractures (around the tip), and 3 type III fractures (distal to the tip) . Eight femoral components were well fixed, and 7 fractures were combined with loose femoral components. The fractures with stable femoral components were treated by open reduction and internal fixation (ORIF) . In type II, 2 fractures were fixed with A0 plates and 2 with Mennen plates. In type III, one was fixed with a Mennen plate and Ender pins, one with a cable plate, and one with a May plate. In the fractures com-bined with loose femoral components, revision THAs were performed with cementless, long femoral components (Huckstep prosthesis) and ORIFs were done at the same time. Autografts of the iliac bones were done in all cases. In the revision THAs, we attempted to restore femoral bone volume and bone quality with autografts, allografts and artificial bones (hydroxya-patite and AW glass ceramic) .
All fractures united without complications, and the final hip scores were assessed to be from 68 to 98 points (average, 78 points) according to the criteria of the Japanese Orthopaedic Association. All femoral components had good fixation.
The goals of treatment of these fractures included a united fracture in near anatomical alignment, a stable prosthesis, a return to prefracture function, and early mobilization. The choice of the most appropriate treatment depended on the location of the fracture, the stability of the implant, and the quality of bone stock.
We prefer ORIF for the treatment of fractures of the femur when the femoral component is stable, and revision THA using a cementless, long femoral component (Huckstep prosthesis) when femoral components are loose.

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The correlation of polyethylene socket thickness and femoral head size (22, 28 and 32 mm) to wear was investigated from retrieved total hip prostheses (22-mm Charnley; 28-mm Bioceram; and 32-mm Müller) . When the socket thickness was less than 9 mm, the larger the femoral head, the higher the linear wear rate. At 9 mm, the linear wear rates of the three types of prostheses were about 0.13 mm/year. At greater than 9 mm, the larger the femoral head, the lower the linear wear rate. When the socket thickness was less than 11 mm, the larger the femoral head, the higher the volumetric wear rate. At less than 11 mm, the volumet ric wear rates of the three types of prostheses were about 31 mm³/year. At greater than 11 mm, the volumetric wear rates of the three prosthetic sockets were approximately the same. The wear rate of the cross-linked socket irradiated by 100 Mrad was very low, with no correlation to socket thickness.

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This paper describes a new exposure direct lateral approach to the hip through the gluteus medius by anterior half osteotomy of the greater trochanter. To provide wide exposure of the surgical area a Charnley's transverse retractor is used and a Calipers Dual Pin Retractor is inserted over the edge of the acetabulum to obtain equalization of leg-length discrepancy during operation. In cases with residual subluxation, an acetabular roof osteotomy was carried out to increase lateral coverage of the acetabular cap. The reconstruction method of the cases with central migration is described. A relatively short follow-up study of cementless total hip arthroplasty with femoral head grafting for acetabular bone defects is presented. Cases were divided into two groups for analysis: Group S (Sg) comprising structural (bulk) bone graft for acetabular bone defects and Group C (Cg) comprising chipped (spongious) bone grafts. Forty-eight hip joints of 46 patients underwent porous coated cementless THA. The average postoperative period was 5 years and 4 months. Classification of bone defects for each group was as follows: Type 1: External margin of the iliac bone (non-weight bearing area) ; Type 2: Weight bearing areas (more than 30%) of the acetabulum; Type 3: Full circumference. Resorption of grafted bone which had protruded from the acetabular beak was seen in all Sg, 4 cases in Type 1, and 3 cases in Type 2. Radiolucent zones were seen extensively across the acetabulum in 6 cases in Cg. All of these were Type 3. However, none of the patients in Sg showed in Type 3. Six mm cup migration in depth in 2 cases was seen within a month because of the unstable placement of the cup. However, osteolysis of the pelvis and revision of the THA were not encountered in any patient.

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Insufficiency fracture, which occurs without any apparent accident due to increased bone fragility, has been highlighted in recent years. We conducted bone histomorphometry with respect to 5 insufficiency fractures of the femoral neck in 4 hemodialysis patients, l male and 3 females aged between 55 and 71 years (mean age: 63.8) at the time of fracture. Patients had undergone dialysis before fracture for a period of from 11 months to 18 years and 10 months (mean: 9.1 years) . Prosthesis replacement was conducted for 2 fractures, hemorrhagic redress-ment/internal fixation using a dynamic hip screw for 2, and conservative therapy for one. Bone histomorphometry showed adynamic bone disease (ABD) in 2 patients, osteomalacia (OM) in one, and ostitis fibrosa (OF) in the other. Osteosynthesis conducted in one ABD patient was failure due to marked loosening and nonunion. A cautious approach is necessary, taking the possibility of ABD into account, when considering osteosynthesis for insufficiency fracture in hemodialysis patients.

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The purpose of this study was to investigate the histological change in a bone tunnel after anterior cruciate ligament (ACL) reconstruction using the bone-patellar tendon-bone graft in a dog model. Eighteen adult mongrel dogs were used. After excision of the ACL, the graft was routed through the bone tunnels and the bone plugs of both ends were fixed with interference fit screws. Four dogs were sacrificed at each of the 4 time periods (one, 3, 6 and 12 weeks) and 2 other unoperated dogs were used to examine the normal insertion sites of the ACL and the patellar tendon. In the histological examination, bone blocks containing the bone tunnels were isolated and decalcified, then, longitudinal sections in line with the bone tunnel were made. The sections were stained with hematoxylin and eosin and safranine-o and observed under light microscopy. Moreover, 4 operated knees (one knee at each of the time periods) and 2 unoperated knees were examined immunohistochemically to clarify the localization of collagen types I and II at the tendon insertion. At the bone-bone interface, incorporation of the bone plug with the host bone was completed at 12 weeks. Structure of the tendon insertion of the grafted patellar tendon, consisting of 4 zones (tendon, uncalcified fibrocartilage, calcified fibrocartilage, and bone), were observed without apparent necrotic or degenerative change for up to 12 weeks.At this original insertion site, presence of cartilaginous matrix and type II collagen was observed throughout the period. Between the tendon and the bone tun-nel, a layer of hypercellular fibrous tissue gradually became mature over time. The dead space in the bone tunnel close to the joint was filled with rather hypocellular fibrous tissue at one week, and the intervening tissue became dense at 12 weeks. The tendon in the bone tunnel underwent the same process of remodeling as its intra-articular portion. Firm incorporation of the bone plug with original insertion and longitudinal fiber orientation of the tendon observed in this study may imply the reestablishment of attachment similar to that of the native ACL. These results suggest a potential advantage of the bone-tendon-bone graft over the tendon graft in terms of graft anchoring in the bone tunnel.

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