Introduction

We developed original KKS non-cement THA system and used clinically over 10 years. KKS means Keio Kyocera Series. This system was developed co-ordinating with Keio-University and Kyocera Company in Japan. Our concept was to make original THA system suitable for Japanese people. Osteoarthritis of the hip in Japanese people caused mainly from developmental dysplasia of the hip. So the shape of femoral medullary canal is characteristic compared with foreign patients. We analyzed the femoral medullary canal shape in typical Japanese osteoarthritis 50 cases of the hip by the use of CT scan. From the results of these analyses, we determined the optimal shape of KKS non-cement stem for Japanese patients. It has double tapered shape in distal stem shaft. Proximal taper angle of the stem is 4 degree, and distal one is 3 degree. The proximal part of stem has characteristic notch in anterior and posterior and lateral surface to tolerate rotational stability.

Introduction

We have used CT-based navigation system for THA from 2004 (Fig, 1). The purpose is to set acetabular socket in optimal position. We have used two different matching methods in these navigation THA surgeries. The old one is Land-mark matching method (L-method), using conventional paired point matching procedure during surgery. The new one is CT-based fluoroscopy-matching system (F-method), that is new technology of image matching procedure before starting surgery (Fig. 2). We compared the accuracy of socket setting angle with these two systems and discuss the usefulness of navigation system.

Dislocation after total hip arthroplasty (THA) remains a significant clinical problem. The acetabular cup position is one of the main factors in the incidence of dislocation after THA. We reviewed dislocation cases in 247 primary THA

Between 1997 and 2001, 247 patients underwent a primary THA procedure. The original diagnoses in these patients were as follows: osteoarthritis (OA, n = 190), osteonecrosis (ION, n=28), rheumatiod arthritis (RA, n=16), and rapidly destructive coxarthropathy (RDC, n=13). A posterolateral approach was used in all cases. We examined mainly the acetabular cup position (ante-version and inclination angle) using anteroposterior radiographs

Six dislocations (2.4%) occurred : three anterior dislocations and three posterior dislocations. Dislocation rate according to the original diagnoses were as follows, 2 dislocations in OA (1.1%), 2 dislocations in RA(12.5%), 2 dislocations in RDC(15.4%) and no dislocation in ION. All cases were treated with close reduction and no component revision was needed. On X-P measurement of setting the acetabular cup in all cases, the mean ante-version angle was 16.3617;6.8 degrees and inclination angle was 43.3& #61617;7.3 degrees. In comparison with these measurement values, there was no statistical difference between the dislocation groups and no-dislocation groups. The number of the cases within Lewinnek’s safe zone in acetabular cup was 178 (72%). The dislocation rate in these 178 cases was low (1.1%).

Setting the acetabular cup in adequate position is one of the major factors avoiding dislocation after THA. We have been performimg computer - assisted THA since 2003. Computer - assisted surgery enables the acetabular cup position to be precisely planned before surgery and allows superior positioning during surgery.

We investigated the incidence of PE (Pulmonary Embolism)and DVT (Deep Vein Thrombosis) after THA by the use of MDCT (multi-detect or row CT scan). The purpose of this study was to evaluate the meaning of blood coagulation molecular markers (FDP D-dimer, Soluble Fibrin Monomer Complex) for the prospect of PE and DVT after THA.

We studied 30 THA patients. There were 2 men and28 women. The value of D-dimer and SFMC before and after THA was examined. MDCT was carried out for DVT and PE investigation, in all cases 7 days after-THA. The relation between the values of blood coagulation molecular markers and existence of PE and DVT was evaluated.

PE occurred in 2 cases and DVT in 4 cases out of 30 cases. D-dimer values of these 2 PE cases in 7 days after THA were higher (18,39), compared with average values (12). Among DVT 4 cases, in 1 case DVT existed on thigh and in other 3 cases existed on calf. The SF values in 7 days showed extremely higher in only thigh DVT case (99), compared with average values (16.6). The value of SFMC fell down rapidly in a few days, representing the biphasic property.

MDCT is very effective for the diagnosis of PE and DVT. But it is difficult to make examination many times. It is very convenient to be able to evaluate PE and DVT by blood examination. From the results of this study, D-dimer may be sensitive for the diagnosis of PE and SFMC also may be useful for DVT. SFMC reacts more rapidly to abnormalities of thrombus and hemostasis. So it has possibilities to clarify the temporal responses of the DVT and PE more precisely.

Since the autumn of 2003, a computer-assisted system (VectorVision® Hip, version 2.1, Brain LAB, Germany) has been used to perform total hip arthroplasty (THA) operations in our hospital. In the present study, the postoperative acetabular cup position was evaluated using the records of the system and the data measured from postoperative radiographs.

To date, 18 patients have been treated using this-system. We studied the cup inclination and anteversion records in this system recorded in the THA procedures. We also measured the cup inclination and anteversion using postoperative radiographs, according to the method described by Pradhan. The inclination and ante-version were the ‘operative’angles for this system and were the ‘radio graphical’ ones for measuring from the radiographs according to the definition described by Murray.

The initial planning of the acetabular cup position was 45° ‘operative’ inclination and 20° ‘operative’ ante-version. From the system records, the average ‘operative’ inclination was 46.5°± 3.9° and the average ‘operative’ anteversion was 25.5°± 6.0°. The average ‘radio graphical’ inclination measured from the postoperative radiographs was 49.0°± 6.0°, and the average ‘radio graphical’ anteversion was 10.6°± 5.8°.

Between the ‘operative’ angles from this system and the ‘radio graphical’ angles from the postoperative radiographs, the inclination was approximately the same, while the anteversion was different. When the ‘radio graphical’ anteversion was corrected for X-ray beam spreading and then converted to the ‘operative’ anteversion, the resulting ‘operative’ anteversion was 21.1°± 7.8°. And when the ‘operative’ anteversion recorded by this system was corrected for the pelvic tilt, the corrected ‘operative’ anteversion was 22.1°± 6.5°. The average difference between these corrected ‘operative’ anteversion in each case was 5.8°± 3.8°. Especially in 10 of the 18 cases, each difference was within 5°. The accuracy of the cup position using this computer-assisted system was shown by this study.

We developed K.K.S. (Keio-Kyocera Series) THA sytem. The aim is to develop original THA system suitable for Japanese patients. We produced MCF (means Medullary Canal Filling) stem, based on the anatomical anlysis of Japanese typical osteoarthritic patients (53 cases) by the measurements with CT scan. By the use of this stem, excellent canal fitting and initial rigid fixation can be obtained. We used this stem together with non-cement porous socket from 1992. At first the surface of this stem was smooth (S groupe), from 1994 the surface was altered to porous surface (P groupe), and then from 1995 HA coating to porous surface (H groupe) was added. The purpose of this study is to compare the biological fixation ability among stems with same shape and different surface.

Material and methods: Materials were patients for which Non-cement K.K.S. THA was done, 33 cases, 35 joints. Average age at operation was 55 (43-64) years old. Follow-up terms were 5-8 years. According to stem surface, all cases were divided to 3 groupes (S: 14 joints, P: 10 joints, H: 11 joints) and evaluated clinically and radiographically. The evaluation was done at the point of 5 years after operation for all cases. Clinically existence of thigh pain was evaluated. Radiographically sinking of the stem and osteolysis around femur were evaluated.

Results: Thigh pain was existed on S group: 6/14; 43%, P groupe: 0/10; 0%, H groupe: 2/11; 18%. Stem sinking was seen only on S groupe: 12/14; 84%. Osteolysis was seen only on 1 joint in S groupe. The result of S groupe was apparently poor clinically and radiographically.

Conclusion: To keep the early biological fixation of stem, not only anatomical shape for getting excellent canal fitting but also porous surface structure is needed.