Sixty-five hip joints in 48 cases with rheumatoid arthritis (RA) were surveyed for 6 months to 15 years (average 51.8 months) after total hip arthroplasty (THA) with Charnley type prosthesis. In subsequent clinical evaluations, results showed stable recovery with a remarkable improvement in pain. The incidence of clear zone (CZ) in the socket side was 50.8%, where CZ was often observed in Zone I and II. The incidence of CZ was higher at a socket setting angle of 40° or less than at one of 41° or more. CZ incidence was also higher in cases of protrusio acetabuli. There were no significant differences in CZ incidence in terms of the cement mantle, and with or without bone graft. The incidence of CZ in the stem side was 12.7%, high in Zone I, and also higher on the medial side than on the lateral side. There was a high incidence of CZ in the stem placed at a varus position, and in cases with an insufficient bone-cement mantle.

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Nineteen rheumatoid patients suffering from rheumatoid spondilitis with myelopathy were surgically treated using Luque segmental spinal instrumentation (SSI) . We studied 7 cases of patients who underwent postoperative magnetic resonance imaging (MRI) evaluation after being treated with titanium Luque SSI. Titanium implants were imaged safely and there was no evidence of implant migration or local tissue heating effect. MRI also allowed postoperative cervical spine imaging without significant image distortion. This titanium Lu-que SSI method affords rigid fixation, allows early mobilization, and MRI serial imaging in the patient's lifelong medical care.

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Clinical evaluations were carried out on 102 joints of bipolar endoprostheses (OMNIFIT®; Osteonics, Allendale, N.J., U.S.A.) more than five years after surgery. Average age of patients at the time of surgery was 49.5 years. The average follow-up period was 69.9 months. Eighty-eight joints (86.3%) were diagnosed preoperatively as secondary dysplastic osteoarthritis of the hip. Acetabulum reaming had been performed on ninety-four joints, and bone grafting acetabuloplasty on twenty-nine joints. The mean J.O.A. (Japan Orthopaedic Association) Hip Score improved from 51.1 before surgery to 84.5 five years after surgery.
At five years after surgery, of the cases with acetabulum reaming, 83 joints (88.3%) had superior migration of the outer head. There was a positive correlation between the distance of the superior migration and the rate of the grafted bone in the acetabulum. It has been believed that bone grafting acetabuloplasty prevents the acetabular component from superior migration in short-term follow-up, however, it failed to prevent this migration, in most cases at five years after surgery.
The migration of the outer head and/or osteolysis around it could lead to loss of bone stock in both the acetabulum and the femur. Therefore it may be necessary to replace not only the acetabular components but also the stems if corrective surgery is required. These complications are contrary to the first concept of the bipolar endoprosthesis.
Abrasion of the UHMWPE rim of the outer head was seen in 9 cases in 16 failed hips, which may lead to component breakage, as well as to migration or osteolysis. Osteolysis was observed in 33.3% of the joints around the outer head and 37.2% around the stems. In conclusion, it seems inappropriate to use this system in cases that require acetabulum reaming, especially in cases of dysplastic osteoarthritis of the hip.

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The reparative process of frozen allograft was investigated by replacing a segment of the femoral diaphys in 43 adults mongrel dogs by allograft. Results were subject to microangiographical and histological analysis, and findings were compared with autograft cases. In the allografts, penetration of newly formed small vessels from the marrow cavity of the host was observed at 2 weeks. Revascularization of the entire marrow cavity was established at 8 weeks. Histologically, bone marrow was normalized at one year, however, vascularization was not. In the cortical bone of the allografts, small vessels penetrated from the marrow cavity of the host at 8 weeks. At one year, dead bone remained, although repaired bone surrounding Haversian's canals was histologically observed. In contrast, the marrow cavity in the autografts was completely normalized at 8 weeks, and at 24 weeks extensive repair of bone was seen surrounding the Haversian's canals. From these results, it was concluded that vascularization in an allograft occurs from the marrow cavity of the host and that, compared with an autograft, a long recuperative period may be necessary for complete repair.

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Vascular changes and growth retardation in the femurs of developing rabbits were observed to ascertain the effect of administration of steroids on bone. Forty female Japanese white rabbits, six weeks old at the start of the study, were used. The animals were divided into two groups: one of 25 animals that received a weekly dose of 2.5 mg/kg of methylprednisolone acetate, and a control group of 15 animals that received no drugs. Vascular changes were investigated by microangiography and histopathology at two-week intervals over a period from 2 to 12 weeks. Growth retardation was assessed by radiographs over the same period. The number of small vessels were counted using a microscope, and the percentage of marrow fat cell area was measuring using a transmission type digitalizer and an image analyzer. At Week 4, microangiography showed numerous small vessels in the steroid group, and marrow fat cell volume was significantly higher than that in the control group. At Week 12, microangiography revealed newly formed vessel caliber. The number of small vessels and the fat cell volume were normalized; however, histopathologically, there was no significant degeneration of vascular tissue. Throughout the study, the average length of femurs in the steroid group was signicantly less than that of animals in the control group. At Week 8 and Week 12, the average epiphyseal width of the steroid group in creased compared with that of the control group. In conclusion, blood supply was impaired in the femurs of rabbits in the steroid group, which was followed by subsequent normalization. This study implies a possible relationship between growth retardation and change in blood supply in rabbits which are administered a steroid.

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This study investigated 41 patients (56 joints) with rheumatoid arthritis which had undergone total knee replacement using a kinematic total knee system at least three years prior to the study. Subjects were followed for a mean period of 66 months (range, 40-96 months) . Average range of motion, tibia! radiolucent lines, complications, and rate of deviation from the center of the knee joint were evaluated immediately after the operation and during the follow-up period. Results showed that limitation of extension improved, but average range of motion decreased significantly from 104° to 95° . Tibial radiolucent lines one or more milimeters in length were observed in 29% of the knees at follow-up. Post-operative deep wound infections occurred in three joints (5%) ; one prosthesis had to be re moved. The ideal deviation rate should be set at within 1-20% of the valgus position from the normal Mikulicz line.

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A new design for a total hip prothesis was developed, combining an alumina ball and polyethylene-backed alumina acetabular cup which has an alumina bearing surface. The outer polyethylene surface has grooves for anchoring cement when fixed to the acetabulum. Moreover, the opening rim of the acetabular cup is covered with polyethylene to prevent alumina exposure which results in alumina-metal neck contact and impingement. This design with a polyethylene cover, which makes a major difference in function from those developed by P. Boutine³⁾ and L. Sedel¹⁶⁾ , will work to reduce the incidence of metal debris problem between the alumina cup rim and the metal neck, and alumina component fracture and loosening between the accetabular cup and the cement.

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The Murata-Chiba (MC) cup supporter is an innovative acetabular cup for treatment of protrusio acetabuli in patients with rheumatoid arthritis (RA) . Six hips of 5 RA patients who had undergone uncemented total hip arthroplasty (THA) using the MC cup supporter combined with autologous bone graft were investigated. The average follow-up period was 23 months (range: 12-29 months) . Clinical results, represented by JOA scores, were satisfac tory. Antero-posterior (AP) X-ray findings showed circumferential bone union after three months. There was no acetabular migration or case loosening. In light of these findings, the MC cup supporter used in conjunction with THA is a recommended operative method for treatment of the RA hip.

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Postoperative results and problematical points of arthroplasty in severe post-traumatic elbow joint contracture were studied. Over a 5-year period, arthroplasty for post-traumatic elbow joint contracture was carried out on 16 elbow of 15 patients (14 males and 1 female) .
Age at the time of arthroplasty ranged from 12 to 46 years (average 25.7 years) . The period from time of injury to arthroplasty ranged from 6 months to 6 years (average 18 months) . Causes were 7 dislocation fractures of the elbow joint, 4 transcondylar fractures, 3 olecranon fractures, 1 radial head fracture, and 1 osteochondral fracture. The period of postoperative observation was 27 months, on average. The causes of joint contracture were considered, and there was a high incidence of contracture in the posteromedial joint capsule, ulnar collaterall ligament, and posterior osteophyte.
No apparent differences were observed in causes or age at operation, but the duration of preoperative symptoms tended to affect prognosis. Since many cases could not maintain the range of joint motion obtained during surgery, it seems that acquisition of sufficient intraoperative range of motion is necessary. Although short-term results were relatively favorable, it was considered that long-term postoperative observation is also necessary, because in some cases there was postoperative progression of joint deformities, while in others there was decreased muscle strength after surgery.

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Magnetic resonance imaging (MRI) and arthrography were performed on 90 knees to compare the diagnostic value for meniscus injury with these techniques. The diagnostic accuracy of MRI and arthrography was 89.1% and 87.1%, respectively. Imaging of the medial meniscus was somewhat better with arthrography, and delineation of the lateral meniscus was somewhat better with MRI. MRI was superior in diagnoses of horizontal and de generative lacerations, but showed the shape of the injuries less clearly than with arthrography. The diagnostic accuracy of MRI decreased with the age of the patient and was inferior to arthrography for patients in their forties or older. In conclusion, MRI is a less invasive approach with high diagnostic accuracy for meniscus injury and is a promising substitute for arthrography.

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Follow-up studies were carried out to ascetain changes of grafted bone and the appearance of radiolucent zones at the acetablum on X-rays of 177 hips in 148 cases after cemented total hip replacement. The length of the follow-up studies was from 3 to 6 years. Bone graft was performed on the dysplastic acetabulum 97 to cover the entire area surrounding the socket. The patient's own femoral head, with osteoarthritis removed during the operation, was used for the graft bones. The grafted bone was alive on the weightbearing zone in almost all of the cases.
Two to five years after the surgery, absorption of grafted bone was seen in 30 hips (16%) and had stopped in 29 hips (97%) . Radiolucent zones were found in 11 hips (6.2%) . The appearance rate of radiolucent zones was significantly reduced by bone grafting, especially at Zone 1 and Zone 2. No radiolucent zone was observed at Zone 1 and Zone 2 in 147 hips in which no grafted bone was absorbed. Some causes of absorption of grafted bone were believed to be severe bony atrophy and multinodular cysts in the grafted femoral head at the time of surgery. As a result, the survival rate of grafted bone was excellent.

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