Aims

Patients with differentiated thyroid carcinomas (DTCs) have a favourable long-term survival. Spinal metastases (SMs) cause a decline in performance status (PS), directly affecting mortality and indirectly preventing the use of systemic therapies. Metastasectomy is indicated, if feasible, as it yields the best local tumour control. Our study aimed to examine the long-term clinical outcomes of metastasectomy for SMs of thyroid carcinomas.

Aims

To evaluate the perioperative complications associated with total en bloc spondylectomy (TES) in patients with spinal tumours, based on the extent and level of tumour resection.

Introduction

Since 1989 we have been using custom lateral-flare stems. Using this stem, its lateral flare can produce high proximal fit and less fit in distal part. Applying this automatic designing software to the average femoral geometries, we can make off the shelf high proximal fit stem (Revelation ®). Putting the off the shelf stem, the original center of the femoral heads were well reproduced. But in DDH cases, severe deformities around hip sometimes make complicated difficulty for better functional reconstruction. They are high hip center such as Crowe II-IV, shortening of the femoral neck, high anteversion etc. DDH cases are well known to have higher anteversion than non DDH cases. There would be no definite explanations for it. The high anteversion would not always be harmful for the preoperative patients. But in some cases, osteophytes are observed at posterior side of the femoral head which make another sphere with different centre. We can guess that the patient's biomechanics had not been matched with the original anteversion. Then posterior osteophytes can correct inappropriate anteversion (self-reduction.) (Fig.1) In those patients, reduction of the anteversion by putting stems twisted into the canal or using modular stems are sometimes done by the surgeons' decision.

Younger DDH cases can also be treated with THA, because of the complicated deformities or biomechanical disorders. Short stems are expected to reduce operative invasion and stress shielding then can reserve bone quality and quantity. From these point of view to improve the understanding of the characteristics of the DDH anteversion, and design a DDH oriented short stem could be one of good solution for those cases.

Introduction

In DDH cases often have high anteversion. They also often have high hip center. THA for those cases sometimes requires subtrochanteric derotational/shortening osteotomy. To achieve good results of the surgery, accurate preoperative planning based on biomechanics of the high anteversion cases, method for accurate application of the plan, and stable fixation are very important. At ISTA 2008, we have reported that the location of the anteversion exist several centimeters below the lesser trochanter. Independently from the extent of anteversion, femoral head, grater trochanter, and lesser trochanter are aligned in the same proportion. We have also reported in 2007, in improper high anteversion cases, many cases grow osteophytes posterior side of femoral head to reduce it functionally. In 2014, we reported about development of the stem for subtrochanteric osteotomy. (ModulusR)[Fig.1] In the present study, we established systematic planning way for estimate proper derotation and shortening and apply it for the surgery.

Background

Infection is one of the most severe comlications of the total arthroplasty. We sometimes encounter cases, which are very hard to finish repeated recurrence. Usage of steroids, immunosuppressants, and biologics would possibly effect to the incidence of the prosthetic infection and to the result of its treatment. Biologics have drastically decreased the number of the total arthoplasic patients, on the other hand, we must be more careful about the infectious conditions. For the infection two stage revision surgery; first removal and antibiotics cement spacer insertion then reimplantation later; is often chosen but sometimes one time antibiotics cement spacer cannot stop the infection and requires multi times spacer insertion. In those cases the dead spaces, poor blood supply and tight skin could be the cause of the recurrence. For these cases we had been performing musclo-cutaneal flap and successfully finish the infection.

Introduction

Since 1989, we have been developing lateral flare stem. The concept of lateral flare stem is to deliver proximal part big enough to fill the proximal cavity that most of the cement stems can fill and most of the cementless stems cannot. Also having distal part polished, much less distal load transfer occurs than cement stem. Thus, we can expect high proximal load transfer to prevent stress shielding. To deliver lateral flare stem, straight insertion path cannot be available, as proximal lateral part to fill inside the greater throchanter collides to the greater trochanter. So 3-Dimension insertion path was calculated to deliver that part through the narrow made by neck osteotomy. The first generation of the lateral flare stem was custom made. The second generation was designed as an off-the-shelf stem from what we have learned by the experience of custom stems. With the third generation, the stem was shortened to achieve more proximal load transfer.

Direct Anterior Approach (DAA) developed by Judet is one of less invasive hip approach. With a stem with straight insertion path, the extended line of proximal femoral axis should come out of the skin. To achieve this position, proximal end of the femur has to be fully pulled up. (Fig.1) Some of the cases would be able to be lifted up but some have difficulty. Using lateral flare stem with curved 3 dimensional insertion path, even the axis extension does not come out of the skin, it would be expected to be inserted. In the present study, 3D insertion path of the lateral flare short stem for DAA was analyzed.

Introduction

During THA in lateral position, keeping accurate lateral position is very important for obtaining good cup position. We normally use two kinds of hip positioner, but sometimes we can only use universal positioner provided with operational table. The pelvic tilt can be changed by surgical procedures such as traction, dislocation, reduction and so forth. In the present study, pre-op and post-op pelvic tilt was assessed using Kinect (Xbox 360′s sensor) as 3D scanner.

Objective

This study shows the radiographic results of total hip arthroplasty (THA) using the Revelation hip system^® for hip joint disease.

Introduction

In THA of DDH cases, sometimes shortening and/or derotational subtrochanteric osteotomy is required, for cases with high hip center and/or high anteversion. Initial fixation is one of the most important problems after subtrochanteric osteotomy. To prevent rotational displacement V-osteotomy or step osteotomy is often used. Even though until the osteotomy part unites, additional fixation is required. When a stem with distal load transfer was used body weight can be transferred to healthy part, so early full weight bearing should be expected. However, the muscles around hip joint can pull up proximal part, so it would be possible osteotomy part to be split. When a stem with proximal load transfer, body weight would be loaded on non united osteotomy part. So full weight bearing could sometimes be postponed. A stem that has both proximal and distal load transfer, and has facility for prevent rotation, those situations would possibly be simply solved.

Lima (Italy) has a proximal load transfer conical stem with fins “Modulus” and a distal load transfer conical stem “Revision.” Combining these two stems, a stem as explained prior was designed. In the present study, applicability of the stem for cases such as subtrochanteric osteotomy was assessed.

Introduction

Patient specific surgical guide (PSSG) is a relatively new technique for accurate total knee arthroplasty (TKA), and there are many reports supporting PSSG can reduce the rate of outlier in the coronal plane. We began to use PSSG provided by Biomet (Signature®) and have reported the same results. Before using Signature, we performed TKA by modified gap technique (parallel cut technique) to get the well balanced flexion gap. Signature is the one of the measured resection technique using the anatomical landmarks as reference points on the images of CT or MR taken before surgery. We usually measure the center gap width and gap balance during operation with the special device “knee balancer”(Fig. 1) that can be used on patella reposition. After cutting all of the bone with Signature, gap balance in the extension position was very good but the gap balance was shown slight lateral opening in the 90 degrees flexion position. So we have changed the surgical procedure. We use Signature for cutting only distal femur and proximal tibia to get extension gap and apply the modified gap technique to decide the rotation of the femoral component (Signature with modified gap technique).

The purpose of this study is to compare the gap balance between the two techniques.

Introduction:

Obesity is one of the biggest issues to harm health so as increase medical costs worldwide. Unfortunately, Japan is no exception. Under a big governmental campaign, obese rate in Japanese elderly begins to decrease very recently. However, we cannot help to have impression that our patients who undergo hip/knee replacement surgery have been getting heavier and heavier. The purpose of this study is to examine the change of body mass in our patients and find related factors.

Introduction

We have been developed lateral flare stem and have been using it since 1989. It was custom stem at first. After being experienced, using the same software, off-the-shelf version lateral flare stem (Revelation) was developed in 1996 in the U.S. We could start using it since 2001 in our country. Lateral flare stems are designed to reproduce physiological proximal load transfer lateral side as well as medial side. It was obtained by having bigger and more accurate proximal part with lateral flare. The design is optimized by matching with 3D insertion path.

Using many custom stems including different length and off-the-shelf standard stems, we have come to feel that as for this high proximal fit and load transfer design, it is not necessary to having long distal part and sometimes it is harmful to obtain good proximal load transfer in some situation such as type A (champagne flute) canal. So we have developed short version of the stem. Many makes of the hip stems have included short stems recently. Some aimed to improve easier insertion, some aimed to improve the volume of residual bone quantity. We have aimed to improve proximal fit expecting more proximal and more physiological load transfer to the femur.

This study shows the radiographic results of total hip arthroplasty (THA) using Revelation stem ® (Djo surgical USA) for hip joint disease.

We removed cases which we couldn't follow up, the remaining of the patients who had undergone a primary THA July 2007 to December 2009 in our institution using Revelation hip stem® and 58 cases-65 hips (14 men and 44 women) were possible for progress observation on this study, and radiographic evaluation was done at the time of the last observation. The preoperative diagnosis of the hip included osteoarthritis (OA) in 40 patients, idiopatic, necrosis of the hip in 13 patients, Rheumatoid arthritis (RA) in 4 patients, and femoral head fracture in 1 patient.

Three patients had undergone femoral head replacement (FHA) and 55 patients had undergone THA.

At the time of the last evaluation, spot welds were detected in 63 hips (97%) in zone1 and 7. Demarcation lines, which indicates movement of the stem, were detected in zone3,4,5, but not in the proximal of the stem.

Stress shielding were observed in 32 joints, according to Engh's classification, first degree were 27 joints and second degree were 5 joints. Cortical hypertrophy were detected in 13 joints.

The revelation stem features a lateral overhang structure (lateral flare) and the stem has an expanded proximal geometry allowing the device to rest on both medial and lateral cortices at the metaphyseal level. Above all the stem has anterior overhand structure (trapezoidal structure). The medullary cavity occupation rate is made to increase by these structures. Above all, the stability of the stem is increased by a proximal portion by three point support.

The distal stem is tapered and polished, which prevents the stress loading to a distal portion of the device.

Stress shielding more than the third degree is not detected, and spots welds were detected in the proximal of the stem. These facts indicate that the concept of this stem, transmit loading to the femur bone, at the proximal portion of the stem, would be achieved.

Introduction

Massive defect of the acetabular bone is one of the severe situation in the hip arthroplasty. Installation of cup supporter or acetabular reinforcement device is one of the important method as well as big cup and bone graft etc. Preparing the device to be suitable shape is very important and installing it at the very position where the shaping was intended is also very important to obtain a stable condition for the arthroplasty. When we use navigation system, the device must be programmed in. But it is impossible to programme a device we have bended by ourselves into the system. If we can use a navigation system for such devices for those cases, we can expect better installation. We can fit the device on the patient's bone during the surgery of course; which is the ordinary procedure fot it; but it requires much time and tissue damage maybe with less accurate fitting.

Objective

To investigate the outcomes of patients following the chipping procedures as an alternative to bone grafting in treatment of non-unions after long bone fracture.

Objective

To determine what factors affect fracture healing with low-intensity pulsed ultrasound (LIPUS) for delayed unions and nonunions.

The ratio of the incidence of trochanteric to cervical fractures increased with age in the elderly female population, but the reason for this fact remain unclear.

The purposes of this study were to investigate whether or not there are specificities of the local distribution of mechanical properties at the trochanteric region of the elderly female using a scanning acoustic microscope (SAM). Human proximal femurs were harvested from seven female cadavers (67–88 years) and proximal femur was coronally sectioned into halves across the center of neck. The surface of the coronal section was polished in order to achieve flat surfaces of smoothness well below the surface resolution in scanning with SAM. Bone tissue density and elastic modulus were calculated from the acquired SAM data. Mechanical properties were measured at the lateral and medial trochanter. Cortical bone tissue of the lateral trochanter had significantly lower elastic modulus than that of the medial trochanter in the all specimen over 70s(p<0.05). Trabecular bone tissue of proximal region of the lateral trochanter had significantly lower elastic modulus than that of distal region in all 80s specimens (p<0.05). Decrease of the elastic modulus of cortical bone in the lateral trochanter and low value of the elastic modulus of trabecular bone in the proximal region of the lateral trochanter may be related to the increase of the ratio of trochanteric to cervical fractures with age in the elderly female population.

INTRODUCTION

In total hip arthroplasty, preoperative planning is almost indispensable. Moreover, 3-dimensional preoperative planning became popular recently. Anteversion management is one of the most important factors in preoperative planning to prevent dislocation and to obtain better function.

In arthritic hip patients osteophytes are often seen on both femoral head and acetabulum. Especially on femoral head, osteophytes are often seen at posterior side and its surface creates smooth round contour that assumes new joint surface. (Fig. 1). We can imagine new femoral head center tracing that new joint surface.

Introduction

A Finite Element Analysis (FEA) is often used to examine load transfer between prosthesis and canal. Ordinary, bone elements' type is defined as elastic material. But using this element type for FEA on stem load transfer, the stems will jump out and fly away when the load is removed even friction between the stem and the canal was defined. This is remarkably different from the reality. It happens because the canal elements return to the original shape without the load. But actually, the bone is impacted by the load without returning to the original shape. Meshing the trabecular bone with a collapsible element type, it can collapse and be hardened by the stem pressure.

We have been using Revelation (DJO, USA) with lateral flare for the primary cases whom we can expect high proximal load transfer. We were going to shorten its length to secure proximal load. We have been using Modulus (Lima Corporate, Italy) with conical fixation for the cases we expect mid stem load transfer and neck modification. We were going to extend its length for wider load transfer area. To examine load transfer of the designs the collapsible FEA was used.

Introduction

Navigation system has been used for very accurate surgery. It can also be useful for preoperative planning. A surgeon can understand whole surgery, plan the surgery and perform the surgery three dimensionally and accurately. But the planning procedures should be installed before everything is started. When the surgery will be done in an ordinary method, the surgeon would not find particular difficulties. But in sometimes the surgeon can have unordinary situation such as massive defect that should be treated with acetabular enforcement device and bone grafted. Using postoperative DICOM data which is predicted by preoperative planning using 3D CAD software, we will be able to use the navigation system for those cases with difficulties that is not supported.

Introduction

To obtain a better range of motion and to reduce the risk of dislocation, neck and cup anteversion are considered very important. Especially for the reduction of the risk of dislocation, the mutual alignment between neck and cup anteversion (combined anteversion) is often discussed. A surgeon would compare the neck direction to the calf direction with the knee in 90 degrees flexion. When an excessive anteversion was observed, the neck anteversion would be reduced using modular neck system or setting the stem a little twisted inside the canal with the tradeoff of the stem stability. Another choice would be the adjustment of cup alignment. Combined anteversion is defined the summation of cup anteversion in axial plane and stem anteversion in axial plane. But in realty the impingement occurs with 3 dimensional relationships between neck and cup with very complicated geometries. In that meaning, the definition of the angles could be said ambiguous too. The bowing of the femur also makes the relationships more complicated. Upon those backgrounds, we have been performing 3D preoperative planning for total hip arthroplasty on every case. In the present study, in vivo position of the stem in each case was determined then the anteversion observed on surgical view and anteversion around femoral mechanical axis are compared using 3D CAD software.

Introduction

Achieving high flexion after total knee arthroplasty is very important for patients in Asian countries where deep flexion activities are an important part of daily life. The Bi-Surface Total Knee System (Japan Medical Material, Kyoto, Japan), which has a unique ball-and-socket mechanism in the mid-posterior portion of the femoral and tibial components, was designed to improve deep knee flexion and long-term durability after total knee arthroplasty (Figure 1). The purpose of this study was to determine the in vivo three dimensional kinematics of Bi-Surface Total Knee System in order to evaluate and analyze the performance of this system with other conventional TKA designs currently available in the market today.

Dislocation following total hip arthroplasty is one of the most common complications, occurring in 1% to 5% of all cases. Several causes for dislocation have been suggested that

Mismatching of cup positioning and stem anteversion

Most often positioning of the stem is anatomically predetermined, while the orientation of the cup is much more flexible. Since July 2005, stem first method has been applied for all cases. During this method, canal preparation and stem trial was done first, and then cup orientation was determined according to the stem direction and impingement. For the bigger cups 34mm or 38mm heads were applied in this series. In the present study dislocation ratio was compared to cup first method.

In the stem fist group (SF), the following procedures were done consequently.

Canal was prepared for the stem. Revelation lateral flare high proximal load transfer stem (DJO) was mainly selected. But for the case with high anteversion over 50 degrees, Modulas; conical distal load transfer stem with modular neck (Lima) was selected.

From October 2002 to July 2008, there were 191 THA cases. There were 81 hips in Standard group and 109 hips in SF group. There were 63 females and 18 males in Standard group and 90 females and 19 males in SF group (p=0.41). Average age was 61.0(22–81) in Standard group and 60.2(29–89) in SF group (p=0.53). In Standard group, 64 were replaced for osteoarthritis, 15 for rheumatoid arthritis and two for avascular necrosis. In SF group, 86 were replaced for osteoarthritis, 17 for rheumatoid arthritis and six for avascular necrosis (p=0.53). As for Crowe’s classification, 61 type I, 18 type II and 2 type III were included in Standard group. And 88 type I, 15type II, 4 type III and 2 type IV were included in SF group (p=0.29). Average anteversion of femoral neck were 23.1(−2 to 70) degree in Standard group and 26.2(−4 to 65) degree in SF group measured with CAT scan (p=0.274). MoM bearing surfaces were used with 71 hips (87.7%) in Standard group and 100 hips (91.7%) in SF group (p=0.35). Only in SF group, big metal head were used in 24hips(22%) with 34mm and in 12hips(11%) as 38mm diameter. Average leg length difference between pre and post operation was 11.5mm(0 to 36) in Standard group and 8.0mm(−18 to 30) in SF group (p< 0.05). Average cup inclination was 43.2(25 to 84) degree in Standard group and 40.9 (22 to 66) degree in SF group (p< 0.05). Average cup anteversion was 8.2 degree (0 to 22.8) in Standard group and 7.1 degree (−12 to 30.5) in SF group (p< 0.05). Average operating time was 111.9min (67–150) in Standard group and 97.5min(60–162) in SF group (p< 0.05). Average intra operative hemorrhage was 744ml(10–2757) in Standard group and 487ml(10–1374) in SF group (p< 0.05). The dislocation rate was decreased from 3.7% (3/81 cases) in Standard group to 0.0% (0/109) in SF group.

In conclusion our study suggested that Stem first method and utilization of big metal head would decrease the dislocation rate in primary cases. More bleeding from canal during accetabular reaming was expected. However less bleeding was observed in SF group.

In Far East, including Japan and the Middle East, daily activities are frequently carried out on the floor. Deep flexion of the knee joint is therefore very important in these societies. Some patients who underwent total knee arthroplasty (TKA) in these countries often perform deep flexion activity, such as squatting, cross-leg sitting and kneeling. However it is still unknown that deep flexion activity affects long term durability after TKA. The purpose of this study was to examine the correlation between deep flexion and long term durability.

Between December 1989 and May 1997, 507 total knee arthroplasties were carried out in 371 patients using the Bi-Surface Knee System (Japan Medical Material, Osaka, Japan) at two institutions and routine rehabilitation program continued for one to two months after TKA. One patient who underwent simultaneous bilateral TKA was excluded because of pulmonary embolism within one month. The other 505 knees (370 patients) were divided into two groups according to the range of flexion after our routine rehabilitation program; one group (Group A: 207 knees) consisted of more than 135 degrees flexion knees and the other group (Group B: 298 knees) consists of less than 135 degrees flexion knees. Patients whose follow-up period was less than 10 years were excluded from this clinical evaluation. Range of flexion was measured preoperatively, at the time after routine rehabilitation program, and at the latest follow-up. Knee function was evaluated on the basis of Knee Society knee score and functional score preoperatively and at the latest follow-up. Kaplan-Meier survivorship analysis was performed with revision for any operation as the end point.

In Group A, the mean preoperative range of flexion was 133.0±16.3 degrees, and at the time after routine rehabilitation program, this improved to 139.7±5.1 degrees. This angle maintained to 136.2±14.3 at the latest follow-up. In Group B, the mean preoperative range of flexion was 111.6±20.4 degrees, and at the time after routine rehabilitation program, this improved to 114.5±13.6 degrees. This angle maintained to 118.2±17.8 at the latest follow-up. The Knee Society knee score and functional score was improved from 43.0±16.9 points and 39.0±20.2 points preoperatively to 95.1±5.8 points and 51.8±21.2 points at the latest follow-up, respectively in Group A. The Knee Society knee score and functional score was improved from 37.1±16.7 points and 31.9±18.4 points preoperatively to 92.5±8.7 points and 53.1±26.1 points at the latest follow-up, respectively in Group B. Kaplan-Meier survivorship at 10-year was 95.5% in Group A and 96.2% in Group B with any operation as the end point. The survivorship between Group A and Group B was not statistically significant.

Good range of flexion was maintained and Knee society score was excellent after a long time follow-up for the patients who achieved deep flexion after TKA. Deep flexion was proved not to affect long term durability in this Bi-Surface Knee System.

Canal Flare Index, defined as the ratio of the intracortical width of the femur at a point 20mm proximal to the lesser trochanter and at the canal isthmus by Noble et al,; is considered to express the proximal femoral geometory, but it is usually measured by a plain A-P X-ray. Then it is thought the index is influenced by rotational position of the femur, so we made 3-D femoral model based on CAT scans and measured the canal flare index three dimensionally. Then the effect of observation from rotated direction was evaluated.

CAT scans of 49 femurs (18 male, 31 female) were obtained from the pelvis to the feet. The average age was 60.4 years old ranging from 25 to 82. Forty nine femurs contained 22 osteoarthritis of hip joint, 12 trauma, 9 knee arthritis, 3 avascular necrosis of femoral head, 3 normal candetes. From those data, 3-D models of normal side were individually made for measuring the parameters. 3-D models were made using CAD software. We measured the canal flare index at which the femur posterior condyles were parallel to the plane, reproducing the situation to take A-P X-ray. After that, those 3-D models were rotated and investigated the difference of the value to study the effect of femur position.

The canal flare index was between 2.8 and 6.6 with the average value at 4.65. The stovepipe (canal flare index< 3), the normal range (3~canal flare index< 4.7), the champagne flute (4.7~canal flare index), included 2%(1 femur), 61.2%(30 femurs), 36.7%(18 femurs), respectively. About the effect of rotation, we found the value of canal flare index was more sensitive to proximal femur rotation than the canal isthmus. The results of the canal flare index at the plane parallel to the posterior condyle line varied widely compared with the results at the position considering the anteversion. So it was suggested that the canal flare index at the patella front position does not represent the canal characteristics. It should be argued in 3-D space.

Introduction: For longer lasting and bone conserving cementless stem fixation, stable and physiological proximal load transfer from the stem to the canal should be one of the most essential factors. According to this understanding, we have been developing a custom stem system with lateral flare and an off-the-shelf (OTS) lateral flare stem system was added to the series. On the other hand, dysplastic hips are often understood that they have larger neck shaft angle as well as larger anteversion. In other words they are in the status called “coxa valga.” From this point of view we had been mainly using custom stems for the dysplastic cases before. After off-the-shelf lateral flare stem system; which is designed to have very high proximal fit and fill to normal femora; was added, we have been using 3D preoperative planning system to determine custom or OTS. Then in most of the cases, OTS stem were suitably selected. Our pilot study of virtual insertion of OTS lateral flare stem into 38 dysplastic femora has shown very tight fit in all 38 cases. The reason was analyzed that the excessive anteversion is twist of proximal part over the distal part and the proximal part has almost normal geometry. In the present study, 59 femora were examined by the 3D preoperative planning system how the excessive anteversion effect to the coxa valga status.

Materials and Methods: Fifty-nine femoral geometry data were examined by the 3D preoperative planning system. Thirty-three hip arithritis, 3 RA, 2 metastatic bone tumours, 5 AVN, 1 knee arthritis, 12 injuries, and 3 normal candidates were included. Among them one arthritic Caucasian and one AVN South American were included. The direction of the femoral landmarks; centre of femoral head (CFH), lesser trochanter (LTR), and asperas in 3 levels (just below LTR, upper 1/3, mid femur; A1-3); were assessed as the angle from knee posterior condylar (PC) line. Neck shaft angle of each case was assessed from the view perpendicular to PC line and neck shaft angle form the view perpendicular to CFH and femoral shaft (i.e. actual neck shaft angle).

Results: Average anteversion was 34.4 +/−9.9 degree. CFH and LTR correlated well (i.e. they rotate together). A1, A2, A3 correlated well (i.e. they rotate together). LTR and A1 correlate just a little, LTR and A2 were independent each other. So the twist existed around A1. Neck shaft angle was 138.7+/−6.6 in PC line view and in actual view 130.3+/−4.4. No excessive neck shaft angle was observed in actual view. Even the case that has the largest actual neck shaft angle (140.4), the virtual insertion showed good fit and fill with the lateral flare stem.

Conclusion: In many high anteversion cases, coxa valga is a product of the observation from non perpendicular direction to CFH-shaft plane. Selection or designation of the stem for high anteversion cases should be carefully determined by 3D observation.

One of the most important characteristic of the developmental dysplastic hip (DDH) is high anteversion in femoral neck. Neck-shaft angle is also understood to be higher (i.e. coxa-valga) in DDH femora. From this understanding many DDH intended stems were designed having larger neck shaft angle.

According to the result of our prior study; reported in ISTA 2005 etc.; using computer 3-D virtual surgery of high fit-and-fill lateral flare stem into high anteversion patients, it was revealed that the geometry of proximal femur itself does not have big difference from normal femora but they are only rotated blow lessertrochanter.

It is very important to know what anteversion is, and where anteversion is located, to design a better stem and to decide more proper surgical procedures for DDH cases with high anteversion.

In the present study, the geometry of 57 femora was assessed in detail to reveal the geometry of anteversion and its location in the DDH femora.

Fifty seven CAT scan data with many causes were analyzed. Thirty-two DDH, 3 Rheumatic Arthritis (RA), 2 metastatic bone tumors, 4 avascular necrosis (AVN), 1 knee arthritis, 12 injuries, and 3 normal candidates were included. Whole femoral geometries were obtained from CAT scan DICOM data and transferred to CAD geometry data format. All the following landmarks were measured its direction by the angle from posterior condylar line. The assessed landmarks were

anteversion,

All the directions were measured by the angle from the medial of the femur.

The direction of anteversion and lesser trochanter were well correlated, (R=0.55, Y=0.56X−35) i.e. femoral head and lesser trochanter were rotated together.

The direction of lesser trochanter and aspera in upper 1/6 section had no relation even they are located very close with only several cm distance, (R=−0.03, Y=−0.02X−88) i.e. however the lesser trochanter was rotated, the upper most aspera was located almost at the same direction (−87.5+/−7.58 degree).

The direction of aspera at upper 1/6 and middle femur were strongly correlated. (R=0.63, Y=0.81X-22) i.e. they stay at the same direction.

The results mean that the anteversion is a twist between normal proximal femur (from femoral head and lesser trochanter) and normal distal femur. The twist was located just blow lesser trochanter within several centimeter.

The anteversion has been understood as the abnormal mutual position between femoral neck and femoral shaft. In high anteversion hips the neck shaft angle was also believed to be higher, so several DDH oriented stems have higher neck shaft angle i.e. coxa-valga geometries. It has been believed that the location of the anteversion was around neck part. This study revealed that the deformity was located in the very narrow part just below lesser trochanter. It has been discussed that DDH oriented stems should have fit to different canal geometries, but understanding the biomechanics of abnormal anteversion and its treatment should be more important.

Since 1993, we have been developing preoperative planning system based on CAT scan data. In early period it was used to decide cup diameter and orientation for Total Hip Arthroplasty (THA). It was done using hemisphere object locating proper position and orientation. According to our progress, we have started using it for custom stem designing, stem selection and stem size planning too since 1995. Since 2001, we have been using it for almost all THA cases. We also have started use it for any case we have question about 3D geometries. Since 2005 we started computer planed 2 staged THA after leg elongation for high riding hips and reported at ISTA 2007 too. Now our policy became that every tiny question we have, we shall analyze and plan preoperatively.

In our population, the incidence of the developmental dysplastic hips is higher. The necks often have bigger anteversion, and less acetabular coverage. So we often use screws for cup fixation. The screw direction allowed in thin shell thickness is limited and less bone coverage makes good cup fixation difficult. With highly defected cases and with revision cases the situation is more difficult.

In the present study, we have developed acetabular 3D preoperative planning method with screw direction, length, and for the cases with defect, cup supporter pre-shaping with models and prediction of the allograft volume.

For the less defect cases, geometries of cup with screw holes were requested to the maker and were provided for us. Screws were attached perpendicular to each screw hole. Screw geometries have marks at every 5mm to plan proper length. The cup was located as much as closer to the original acetabular edge, keeping in the limit to avoid dislocation. Small space above the cup was accepted if anterior and posterior cup edge could be supported by original bone. Then the cup was rotated until we can obtain proper screw fixation.

For the cases with severe defects, we use cup supporters and allografts. Cup supporters are designed to be bent and fit to the pelvis during the surgery. But to shape it a properly; for good coverage and strong support; is very difficult and takes long through the limited window with fatty gloves. And mean while we get more bleeding. The geometries were obtained by CAT scan of the devices. Then proper size was determined as cup size. Chemiwood model was made and proper size supporter was opened and bent preoperatively using the model. It was scanned again and compared to the pelvic geometry again.

Using cluster cups, no dangerous screw was found as long as normal cup orientation was decided and screws were less than 30mm. Posterior screws were often too short then rotated anterior and found to have good fixation. Pre-bending could reduce surgical time remarkably.

As long as we could know, no navigation system can control the cup rotation. But acetabular preoperative planning was very useful and could reduce operative invasion. It could be done easily without using navigation system.

Introduction: Soft tissue balancing remains the most subjective and most artistic of current techniques in total knee arthroplasty. The flexion gap is traditionally measured at approximately 45 degree of hip flexion and 90 degree of knee flexion on the operation table. Despite of aiming equal joint gaps or tensions in flexion and extension, influence of the thigh weight on the flexion gap has not been documented. Therefore, the purpose of this study was to examine the flexion gaps in the 90-90 degree flexed position and the traditional 45-90 degree flexed position of hip-knee joints.

Materials and methods: Thirty patients with osteoarthritic knee underwent total knee arthroplasty. After the PCL sacrifice, soft tissue releases, and bone cuts, the specially designed tenser which has two load cells was employed. 160N was applied to open the joint gaps in the traditional 45-90 degree flexed position and the 90-90 degree flexed position of hip-knee joints.

Results: The flexion gap in the 90-90 degree flexed position of hip-knee joints was 2.1±1.2mm wider than that in the traditional 45-90 degree flexed position of hip-knee joints. The flexion gap had significant difference between the two different hip flexion angles (p< 0.001).

Discussions: In the traditional 45-90 degree flexed position of hip-knee joints on the operation table, the flexion gap is approximately 45 degree to the gravitation and influenced by the thigh weight. To avoid the influence of the thigh weight and obtain equal joint gaps or tensions in flexion and extension, the flexion gap should be checked in the 90-90 degree flexed position of hip-knee joints.