Objective: Clinical applications of Total Ankle Arthroplasty (TAA) started in the 1970s. Various TAA prostheses have been developed. Although TAA is excellent for pain relief, loosening and sinking in an early postoperative stage remain as problems since the implant is placed under considerable stress. We developed a new 3-component design TAA aiming at clinical results acquisition over a long period of time, and verified the design.
Methods: From the osteotomy surface and CT data of cadaver bone, contour extraction of the articular surface was performed. Contact stresses on the tibial articular surface were refined using finite element analyses (FEA) . An investigation was performed regarding how changes in the joint's range of motion affect the contact area.
Results: FEA showed peak von Mises stress of 13.0 MPa under a 3, 000 N load, well below the plastic limit of UHMWPE. The overall contact area of the talocrural joint became a constant 600mm² between±10 degrees of dorsiflexion and plantar flexion. For the 2-component prosthesis under standard conditions, FEA showed peak von Mises stress of 19.5 MPa under a 3, 000 N load, with a contact area of 190mm².
Conclusion: FINE® Total Ankle System was developed for the purpose of stress dispersion and easy self-alignment of the ankle joint. From this investigation, it was shown that TAA with this 3 component prosthesis improves stress dispersion.

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The currently available hyaluronan products used in conservative therapy for osteoarthritis of the knee have two different average molecular weights of 900, 000 and 1, 900, 000. The purpose of the study was to determine how the effects of these two hyaluronan products differ in improving joint function. We investigated thirty knee joints of 25 patients who were diagnosed with osteoarthritis, which were treated with the 900, 000-AMW hyaluronan product (15 knees of 13 patients) or the 1, 900, 000-AMW hyaluronan product (15 knees of 12 patients) . The assessment variables were: 1) pain in walking, 2) pain in descending and ascending stairs, and 3) total score based on the Japanese Orthopedics Association's Knee Osteoarthritis Therapeutic Response Rating Scale (JOA score) . In addition, for subjective evaluation of pain-relieving effect based on the visual analog scale (VAS), three parameters were selected: 1) pain at rest, 2) pain on movement, and 3) pain during sleep. The 1, 900, 000-AMW hyaluronan product was proved to be superior in efficacy in respect of all three JOA scores and the pain at rest and pain on movement in the VAS assessment. The high molecular weight hyaluronan product improves joint function as well as ADL and pain from an induction phase of conservative treatment.

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The bisurface knee (KU-type) is an artificial knee joint which has a unique ball and socket joint in the midposterior portion of the tibiof emoral joint. The joint has two surfaces, one for weight-bearing and the other for flexion kinematics. The joint was developed in 1989 in cooperation between Kyoto University and Kyocera Corp. for the purpose of allowing deep flexion after TKA. Between 1990 and 2005, Bisurface knees were implanted for 874 knees in Tamatsukuri Koseinenkin Hospital. Knee joint scores averaged 50 points before surgery, 76 points 4 weeks postoperatively, and 83 points one year after surgery. The percentage of knees with a flexion range more than 130 degrees before surgery was 66% and that score rose to 84% after surgery. The knees that can not flex more than 143 degrees before surgery may obtain a better flexion range after TKA.

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Objective: To evaluate clinical results and radiological changes of grafted bone in rheumatoid arthritic knees treated with primary total knee arthroplasty (TKA) with massive bone grafts to tibial defects.
Methods: Seventeen knees of sixteen patients after primary TKA were evaluated. Average age at surgery was 58.7 years old (range 49 to 69 years old) . The average follow-up period was 8.9 years (range 6 to 16 years) . According to Dorr's classification, 11 knees had peripheral defects. The other 6 knees had central defects. In the peripheral defect knees, local bone grafting was performed in 6 knees, iliac bone grafting was performed in 3 knees, and allogenic bone grafting was performed in 3 knees. In all of the central defect knees, local bone grafting was performed. All implants were fixed using bone cement.
Clinical evaluation was performed using the Japanese Orthopaedic Association RA knee score (JOA score) . Radiologically, lower leg alignment, clear zone around the component, and component angles β and δ according to the knee society TKA evaluation system were evaluated. Furthermore, union of grafted bone to tibia, collapse of grafted bone, and absorption of the grafted bone were evaluated.
Results: The mean JOA score improved from 43.5±7.5 to 81.2±12.1. Knee extension improved from a mean of -15.5±14.7° to -1.5±4.9°. Knee flexion improved from a mean of 91.1±18.6° to 117.5±12.8°.All grafted bone was united at an average period of 4.5 months. In one knee with an allogenic bone graft, collapse of grafted bone and component loosening was observed. This resulted in revision TKA. In two knees, absorption of grafted bone was observed radiologically. One of those two knees underwent allogenic bone graft. These three knees had had peripheral defects.
Conclusion: Bone grafting is a viable alternative to modular metal tibial wedges or excess cement, even for large tibial bone defects. On the other hand, the use of allogenic bone graft should be done with caution.

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Purpose: We evaluated walking ability after total knee arthroplasty (TKA) in RA patients objec-tively by measuring the numbers of steps using a pedometer.
Methods and Materials: We examined 21 patients with RA who underwent TKA in our institute between December 2001 and November 2002. Their postoperative follow-up periods were at least 6 months. The patients walked on the pedometer at before operation and at of 1, 3, 6 and 9 months, and 1 year after operation. We evaluated walking ability after TKA using a pedometer and studied the factors influencing walking ability.
Results: Walking ability in the patients was not strongly related to the severity of joint disease in the lower extremities except in the operated knee. However, young patients (less than 60 years old) showed more improvement. Also, patients whose CRP, as a parameter of control of general RA conditions, was less than 1.0 mg/dl in the post-operation period, improved their walking ability. In addition, limitation of knee extension pre- and post-operation made it difficult to improve walking ability.
Conclusions: This study suggested that the pedometer is a useful device for evaluating walking ability after TKA. Improvement of walking ability was related to the patient's age, CRP in the post-operation period, and limitation of knee extension pre- and post-operation.

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Objective: In this study we measured the position of the anatomical axis of the distal femur relative to the articular surface of the femoral condyle in lateral radiography, and compared the position of the anatomical axis to the position of the femoral stem for total knee arthroplasty.
Methods: We studied 81 knees in 81 rheumatoid arthritis patients. The radiological grade of each knee joint was assessed by the Larsen method, and only knees for which Larsen grade was ≤III were included. The anatomical axis was defined as a line connecting the midpoints of femoral A/P diameter at 6 cm and 12 cm proximal from the distal end of the femur. The distances between that anatomical axis and the lines tangent to the anterior cortex and to the posterior condyle parallel to the anatomical axis were defined as A and B, respectively. The distances between the midline of the stem and the lines tangential to the inferior border of the anterior flange and to the posterior flange parallel to the midline of the stem were defined as a and b in 5 kinds of prostheses. The ratios A/B and a/b were calculated. Next, the proper size of each kind of prosthesis for each patient was determined by laying the template on the lateral radiograph. The distance between the midline of the stem and the anatomical axis was calculated as a minus A.
Results: The mean value of A/B for all patients was 0.38 (SD 0.04) . The mean values of a/b were 0.36 (SD 0.02), 0.44 (SD 0.02), 0.54 (SD 0.03), 0.55 (SD 0.01) and 0.52 (SD 0.02) for models I, II, III, IV and V. The mean values of a minus A were 0.04 mm (SD 1.38), 1.42 mm (SD 1.44), 3.68mm (SD 1.48), 4.30 mm (SD 1.39) and 3.58 mm (SD 1.42) . The stem in models III, IV and V was located significantly posteriorly when compared to the stem in models I and II.
Conclusion: Our results show that the position of the femoral stem in several kinds of components does not correspond to the position of the anatomical axis in most patients. In such cases, one should use an offset stem, However, the sizes of femoral condyles in Japanese patients are often smaller than those of many Western people. Therefore we sometimes cannot insert a femoral component with an offset stem because a portion of the offset would impinge on the posterior cortex of the posterior condyle. We should select prostheses with stems in the proper position.

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Objective: The aim of this study was to evaluate the usefulness of D-dimer for the early diagnosis of deep vein thrombosis (DVT) and pulmonary thromboembolism (PTE), after total knee arthroplasty (TKA) .
Material and Methods: TKA was performed in seventeen patients with osteoarthritis. The patients were 5 males (5 knees) and 12 females (13 knees) with a mean age of 75 years (range 63-86 years) at the time of surgery. We performed pulmonary perfusion scintigraphy to diagnose PTE on the same day after the operations. Four days after surgery we performed ultrasound and venography on the lower extremities to test for DVT. On the 1st, 4th and 7th days after TKA, we checked the D-dimer values.
Results: We divided the patients into two group: 1) Three severe thromboembolism cases; patients who had PTE or wide DVT which required an IVC filter. 2) All other fifteen, mild cases. The mean D-dimer value for severe thromboembolism cases was 22.9±8.8μg/ml on the 1st day, and 27.4±10.5 μg/ml on the 4th day. On the other hand, the mean D-dimer value for the mild cases was 14.6±10.1μg/ml on the 1st day, and 7.8±3.1μg/ml on the 4th day.
Conclusion: The D-dimer levels of patients who had PTE or severe DVT were high on the 1st day after operation compared to the milder cases. In addition, those values became higher on the 4th day, whereas they became lower in the milder cases. We think the comparison of the 1st day D-dimer value and that of the 4th day was useful for early diagnosis of PTE or severe DVT cases.

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An Image-Free Knee Navigation System (Stryker), able to analyze kinematics curves and the kinematics values, was evaluated. Forty-five TKA (26 CR and 19 PS types) were performed using this navigation system. Kinematics curves were categorized into the following groups: a reversed patella group, a reduced patella group and a cramped patella group. This navigation system has a function to predict the post-operative balance of the knee intraoperatively; this was very practical for our evaluation, and unique. Differences between CR and PS knees were evaluated in the cramped patella group. Kinematics values could be recorded only once, so the differences between CR and PS knees were evaluated only in the reduced patella group.
The results show that the medial collateral ligaments of the reversed patella group were more lax than those in the reduced patella group (P<001) and the laxity of the medial collateral ligament in the cramped patella group was less at all angles of the kinematics curves (P<0.01) . Differences between CR and PS knees were not significant. Regarding the kinematics values, PS knees showed more internal rotation than CR knees (P<0.05) .
This study indicates that this Navigation System offers a possibility of evaluating knee kinematics during surgery, and further improvement of the system is required for a better analysis.

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Objective: The short-term results of treatment for Periprosthetic femoral shaft fracture after total hip arthroplasty have not always been satisfactory, especially when the Dall-Miles system was used alone for loosening fractures, when it should be supplemented with additional fixation according to recent reports; but there is always concern about the long-term survival of prostheses. The aim of this study was to evaluate fracture healing and hip functional outcome with a follow-up time of at least 5 years after periprosthetic fractures of the hip, using the Dall-Miles system and strut grafts.
Methods: There were eleven periprosthetic femoral fractures (three Vancouver B1, four B2, three B3, and one type C) . We had used the Dall-Miles cable and plate system supplemented with cortical autograf t from the patient's own fibula. For the five cases with stable implants we used only the Dall-Miles system and bone struts, and for the six loosening cases we revised the implants with associated cables and strut graft support. Fracture union was assessed with plain x-rays, and quali-tative assessment was based on a questionnaire. The average time to fracture from the previous arthroplasty was 6.5 years (range 5 months to 15 years) . The mean follow-up was 6.6 years (range 5-10 years) .
Results: All the fractures united within 18 weeks with no breaking of plates, and no refracture. Pain relief was anticipated and the questionnaire scores were not statistically significantly different between pre-fracture and postoperatively, but there was a trend toward lower functional scores for mid-term postoperatively.
Conclusion: It appears that the Dall-Miles system is a reliable technique to treat periprosthetic femoral fractures. Even when the prosthesis is unstable, the additional use of cortical onlay grafts with cables leads to fracture healing and to keeping satisfactory alignment for a long time, in our opinion.

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In total hip arthroplasty (THA) in patients with rheumatoid arthritis (RA), major concerns includes low bone quality and the relatively young age of the patients. Taking into account the possibility of revision surgery in the future, preservation of bone stock is considered important. We have performed cementless THA using a bone preservation-type stem (BiCONTACT^® stem) in patients with RA. The purpose of this study was to investigate the short-term clinical results of this procedure.
Eighteen hip joints in 14 RA patients, 2 males (3 joints) and 12 females (15 joints), with a follow-up of at least 2 years after surgery were retrospectively enrolled. The average age at surgery was 61.1 years old (range 35-76 years old), and the mean follow-up period was 4.1 years (range 2-5.3 years) . The hip rating score of the Japanese Orthopaedic Association (JOA score) and the existence of thigh pain were used for clinical evaluation. Radiographic evaluations included bone quality before surgery, classified using Engh's bone quality scale, subsidence of the femoral stem, existence of osteolysis around the stem, and the stability of the stem according to Engh's classification.
The mean JOA score before surgery was 32.1 points (range 18-54 points), improving to 74.3 points (62-100 points) at the time of follow-up. No patient complainted of thigh pain after surgery. Bone quality before surgery was good in 3 joints and poor in 15 joints.There was no case showing sinking or osteolysis postoperatively. As for the stability of the stem, bone ingrown fixation was obtained in all hip joints. Regarding postoperative complications, dislocation occurred in one hip joint six months after surgery. In that case no re-dislocation occurred after replacement of the inner head and polyeth-ylene. There was no case needing revision due to problems in the stem.
In spite of the short follow-up period (average: 4.1 years), the clinical results of the cementless THA using the bone preservation-type stem (BiCONTACT ^®stem) were good.

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