Long-term results of kinematic stabilizer total knee arthroplasty (TKA) were assessed clinically using the knee score of the Japanese Orthopedic Association. TKA was carried out on 43 knees of 24 rheumatoid patients. The mean age of patients at time of surgery was 57.3 years and the mean follow-up period was 11.2 years (range 10-15.2) . The average knee score was 36.5 before surgery, which improved to 60.3 at the final follow-up. This was statistically significant (95%CI, P<0.0001) . One patient had femoral loosening but there was no revision surgery. Three patients received intrascopic treatment for pain in the patello-femoral joints. Activities of daily living (ADL) decreased with time in some severe cases with multiple joint destruction, incomplete spinal palsy, and renal failure induced by amyloidosis. Our results suggest that kinematic stabilizer total knee arthroplasty is a good form of treatment for RA patients.

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We have radiographically reviewed aseptic loosening of the acetabular and femoral components in 127 total hip replacements using methylmethacrylate bone-cement. The follow-up was a minimum of five years and used the Kaplan-Meier survival analysis. We have also studied the correlation between the rate of aseptic loosening and early radiographic appearance evaluated according to each cementing grade for both components. Three different types of prosthesis were used: the Charnley-Müller type, Charnley type, and Bioceram type. On the acetabular component the cumulative survival rate at 5 years was 92.9% and at 15 years 36.6%; whereas on the femoral component at 5 years it was 93.7% and at 15 years 85.1%. We confirmed that the rate of aseptic loosening of the acetabular component was higher than that for the femoral component and continued to increase time-dependently in the long-term results. The cementing grade on the acetabular component was evaluated according to the classification described by Ranawat, and on the femoral component by that of Harris. On the acetabular component the survival rate at 10 years was more than 80% in components considered well fixed (grade A, B and C) and less than 50% in those considered not well fixed (grade D, E and F) . Thus the state of the bone-cement interface as shown on the early postoperative radiograph correlated well with the actual long-term radiographic survival of the acetabular component.On the femoral component the survival rates at 15 years were more than 80% for all grades except grade D (gross deficiencies in the cement mantle) .
We concluded that pressurization of the cement is one of the most important factors related to aseptic loosening in cemented THR, and that femoral components implanted with the use of second-generation cementing techniques appear to retain excellent long-term results.

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To elucidate the cellular mechanism of bone resorption in the failure of total hip replacements, 15 interface tissues with adjacent bone were obtained in 11 revision surgeries. The morphology of the bone surface next to the interface membrane was investigated with immunohistochemical techniques and then histomorphometrically analysed.
The bone surface in contact with macrophages amounted to 16.03±5.65% of the total bone surface. The proportion of the osteoclastic bone resorption estimated by vitronectin receptor expression was 8.22±2.94%. The tissues retrieved from the acetabular side showed a tendency to have more osteoclasts and fewer macrophages, although these differences did not reach statistical significance. The tissues retrieved from the sites where radiographic osteolysis was present (n=7) had a significantly higher extent of bone surface in contact with macrophages than did the tissues without osteolysis (n=8, p=0.049, Mann-Whitney U test), whereas no significant difference was observed in the extent of osteoclastic bone resorption.
In summary, we have noted some differences in tissue response at the acetabular and femoral sides, but these differences were not statistically significant. The differences may be due to variation in the mechanical environment and/or variation of particle concentration. Further study is necessary to clarify the possible difference in the mode of bone loss between the acetabular and femoral side. These data also highlighted the role played by macrophages, not as cells producing inflammatory mediators which could activate osteoclasts, but as cells pri-marily responsible for bone loss in osteolytic lesions in total hip replacements.

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Reconstruction by total hip replacement (THR) in patients with dislocated coxarthrosis presents special problems of dysplasia of the acetabulum and shortening of the limb. We designed a custom-made socket that consists of an ordinal cementless metal back socket with a long stem and a metal flange. The concept of the socket is to augment socket fixation by a long stem, to support it by connecting the metal flange with the iliac bone, and to contain grafted bone chips also by the flange.
Three custom-made sockets were implanted in two patients for dislocated coxarthrosis. Capsulotomy was performed prior to THR to pull down the femoral head at the anatomical level by gradual traction. The socket was machined with reference to the mold that was obtained at the time of capsulotomy and the Styrofoam model reconstructed from CT scan data. Structural autograft from the femoral head was performed at the supero-lateral portion of the acetabulum. The socket was fixed by the long stem and also was supported by the lateral metal flange that connected with the iliac bone. A morselized bone graft was then performed in the space contained by the iliac bone and the metal flange of the socket.
The follow-up periods were 2 and 4 years. In both cases, the clinical results were excellent. The union of the grafted bones was achieved and the remodeling was observed roentgeno-graphically. No migration of the sockets or collapse of the grafted bone was observed.
These results were limited due to the short-term follow-up, howerver our method was con-sidered one of the solutions for the acetabular bone deficiency.

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A long-term follow-up study was performed on 74 patients with rheumatoid arthritis (RA) treated with Charnley total hip arthroplasties (THAs), and compared with results for 142 patients with osteoarthritis (OA) . The follow-up term was very similar for the two groups (12.3 versus 13.4 years on average, respectively) . The preoperative score for 34 hips, according to the Japanese Orthopaedic Association (JOA), improved from 34.7 to 64.9 points at the final evaluation in the RA group, while that for 109 hips improved from 43.5 to 79.7 points in the OA group. Clinical results of the RA group were significantly worse than those of the OA group, but 25 patients (93%) of the RA group retained practical mobility. Radiological assessment showed high incidence of mechanical loosening in the RA group (41%), with 16% in the OA group. Migration of the socket in the RA group was more frequent in 10 hips (29%), and there was stem loosening in 4 hips (12%) . In addition to poor bone quality, protrusio acetabuli seemed to be one of the significant causes of socket migration. Although 81% of the RA group had multiple joint replacements in the lower extremity (mean, 2.6 arthroplasties), such procedures did not worsen the clinical results of the THA. In spite of the high incidence of mechanical loosen-ing, the Charnley THA was very useful for pain relief and maintenance of practical mobility for more than 10 years.

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Radical synovectomy with muscle release at the lateral humeral epicondyle and excision of the radial head was performed on 70 elbows of 56 rheumatoid patients. The mean age of the patients was 51.4 years (range 26 to 75) at the time of surgery. The mean follow-up period was 6.7 years (range 2 to 21) . Patients were satisfied with the surgical results in 65 out of 70 elbows. The mean elbow score, evaluated using criteria of Yokohama City University, improved from a preoperative 46.4 points to 76.5 at follow-up. The mean arc of motion improved from a preoperative 70.9 degrees to a postoperative 101.4 degrees. Radiologically, the Larsen Grade was advanced in 26 out of 70 elbows. However, there was no difference in elbow score between groups regardless of grade. There were no severe complications. Radical synovectomy with muscle release at the lateral humeral epicondyle with excision of the radial head was concluded to be a treatment of choice for rheumatoid elbows of advanced grades.

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Rotation of the knee during weight bearing was measured by ultrasound to gain a greater understanding of morbidity of the osteoarthritic knee. In the first study, a highly significant correlation (r=0.989, p<0.01) was noticed between the rotational angle measured by ultrasound and that by computed tomography, and the authors concluded that the rotational angle could be accurately obtained by ultrasound. In the second study, rotation during weight-bearing in 96 knees with medial compartmental osteoarthritis (OA group) and in 40 normal knees (control group) was determined. The rotational angles with the knee at 20°flexion and maximal extension during weight-bearing were measured, and the angular difference between these measurements were defined as the screw home movement (SHM) . The OA group was divided into 3 radiographic grades. At 20°flexion, the mean value of internal rotation in Grade 1 (1.3°) was significantly smaller than that of the control group (4.8°) (p<0.01), and this decrease in internal rotation was the initial phenomenon in the early grade of OA. At maximal extension, the external rotation of Grade 2 (0.1°) was significantly smaller than that of the control group (p<0.01) and Grade 1 (P<0.01) . In Grade 3, internal rotation was observed to have a mean value of 3.8°. The external rotation of SHM decreased with the advance of grade. In the third study, rotation-al change of the knee elicited by contraction of the quadriceps muscle was determined. At 20° flexion, tibia rotated internally by contraction of the quadriceps muscle.
The authors concluded that muscle weakness of the quadriceps brought about the decrease of internal rotation at 20° flexion, and this fact was one of the most important factors in the ini-tial change of SHM in the early grade of OA.

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We report 2 cases of lumbar destructive lesions in patients with rheumatoid arthritis (RA) . A 56-year-old woman with a 14-year history of RA experienced increasing backache over a six-month period. Plain rentogenograms of the lumbar spine showed destructive changes of the vertebral end-plates and facet joints at the L3 and L4 levels, and a lateral slip of L3. Patient underwent anterior lumbar interbody fusion. Histological findings showed nonspecific chroni'c inflammation with granulation and fibrinoid necrosis. Six weeks later, grafted bone was displaced. However, 14 weeks after surgery anterior fusion was achieved, relieving the patient of symptoms.
The second case was a 57-year-old woman with a 10-year history of RA who experienced increasing backache and leg pain over a six-month period. Plain rentogenograms showed destructive changes of the vertebral end-plates and facet joints at the L4 and L5 levels, and a lateral slip of L4. Patient underwent a decompressive lumbar laminectomy and a posterior stabi-lization with the ISOLA system, and simultaneous anterior fusion. Histological findings showed synovial proliferation in L4/5 facet joints, but specific inflammation for RA was not found in the vertebrae and intervertebral disc. The patient was relieved of symptoms. We believe that posterior stabilization with instruments is desirable for maintaining good alignment when there are severe destructive changes in facet joints in RA spondylitis.

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