Introduction

LCS total knee arthroplasty was used in many nations worldwide. This implant's features are not only mobile bearing but also has very unique concepts of mechanism.

Meniscal bearing (MB) is a one of the types of implant. 2 separate bearings move on the tibia plate. This implant has been known to need revision in cases of over ten years. F.F. Buechel¹⁾ reported a 5% revision rate at an average of 10.1 years. On the other hand, another type of implant, which is a rotating platform bearing LCS, had only 1.2% at an average of 9.9 years.

We have been using 3-dimensional CAD software for preoperative planning as a desktop tool daily. In ordinary cases, proper size stems and cups can be decided without much labor but in our population, many arthritic hip cases have dysplastic condition and they often come to see us for hip replacement after severe defects were created over the acetabulum. It is often the case that has Crowe's type III, IV hips with leg length difference. For those cases preoperative planning using 3D CAD is a very powerful tool.

Although we only have 2-dimensional display with our computer during preoperative planning, 3 dimensional geometries are not so difficult to be understood, because we can turn the objects with the mouse and can observer from different directions. We can also display their sections and can peep inside of the geometries. It is quite natural desire that a surgeon wishes to see the planed geometries as a 3-dimensional materials. For some complicated cases, we had prepared plastic model and observed at the theater for better understanding. When we ask for a model service, each model costs $2,500. We also have small scale desk top rapid processing tool too, however it takes 2 days to make one side of pelvis. Observation of the geometries using 3-dimensional display can be its substitute without much cost and without taking much time. The problem of using 3D display had been the special goggle to mask either eye alternatively.

In the present paper, we have used a 3D display which has micro arrays of powerful prism to deriver different image for each eye without using any goggle.

Dislocation after total hip arthroplasty (THA) is one of the most serious complications. We recently modified the design of Lateral Flare femoral component (RevelationV2) with six degrees lower anteversion to reproduce the normal hip condition in Japanese. In addition, we added 10-degree slope on the posterior neck to prevent dislocation especially aimed to high anteversion cases. The purpose of this study is to verify the clinical outcome after this design modification.

Hospital records and database were retrospectively reviewed. We investigated 46 consecutive hips in 43 patients who underwent primary total hip arthroplasty using RevelationV2 from September 2007 to August 2009. All patients implicated preoperative planning using CAT scan with their informed consents.

The mean age and BMI at surgery were 63 years old and 23.1. Preoperative diagnosis was osteoarthritis (40/46: 87%), rheumatoid arthritis (2/46: 4%) or avascular necrosis of femoral head (4/46: 9%). There were 41 hips (89.2%) of Crowe I, 3(6.5%) of Crowe II and 2(4.3%) of Crowe III. Preoperative femoral neck anteversion averaged 28 degrees, whereas postoperative combined anteversion (the sum of femoral neck anteversion and anterior cup inclination) averaged 46 degrees. During follow up, 5 complications, in details, 3 mild peroneal nerve palsy, 1 pulmonary embolism and 1 dislocation following deep infection were reported. In conclusion, although no ordinal dislocation was found in this series, longer observation will need to judge appropriateness of this new component.

One of the ironies in modern technology for arthroplasty is the stress shielding in cementless stems. The aim of the development of cementless stems had been reduction of stress shielding which cement stems are not free from. In healthy femur, trabecula start form the femoral head and reach at both medial and lateral cortex in rather narrow area around lesser trochanter. So the load from the femoral head is transferred at the level on both medial and lateral side. Cement stems should have binding to the cortical bone from collar to the tip of the stem where the cement interlays, and then the load is transferred gradually from the tip to the collar, which means mild stress shielding. When distal bonding is removed, the load could be transferred as normal femur. This should have been one of the biggest requests for cementless stem. But in realty many cementless stems have difficulty to obtain a load transfer at the level like normal femur.

Since 1990, we have been mainly using lateral flare stems to obtain contact on both medial and lateral side at proximal level. In the present study, different types and length of the designs were compared by 3-Dimensional fill, 3-Dimensional fit and Finite Element Analysis.

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 drawbacks of cemented total hip arthroplasty (THA) is aseptic loosening after long period, major reason for which is bioinertness of PMMA bone cement. To improve longevity of THA, interface bio-active bone cement technique combined with modern cementing technique has been used in our institute, and was evaluated clinically and radiologically.

The present study includes 44 cases of primary THA with an average age at operation of 64 years old (ranging 48 to 81). Mean postoperative follow up period was 4 (ranging 3.5 to 5) years.

Pre- and postoperative evaluation using Merle d’Aubigné score were 8.0 and 16.2 points, respectively. Postoperative cementing grade using Barrack’s classification was A or B. At final follow up, radiolucent line at bone-cement interface was not observed, except one case of rheumatoid arthritis patient at zone 3 described by Delee and Charnley in the acetabular side. Neither osteolysis nor loosening was observed in every case. No major complications, such as infection, dislocation, pulmonary embolization, were observed.

The present study revealed excellent short-term result was obtained by IBBC technique combined with modern cementing technique for primary THAs. Most important technical point required for IBBC is to obtain dry bony surface just before cementing. Compressive reamed bone and gauze packing was effective for complete hemostasis just before cementing for the acetabular side, and plugging the isthmus using bone chips was effective for reducing bleeding for the femoral side.

The purpose of this study is to call attention to the diagnosis of spinal cyst caused by lumbar disc herniation. Reviewing a total of 11 cases of lumbar spinal cyst that have been encountered in our spinal practice, we propose our views concerning the pathology of this lesion.

The clinical findings of lumbar spinal cyst are identical to those in acute disc herniation such as low back pain and radiculopathy. The characteristics of imaging study are as follows; The magnetic resonance imaging (MRI) demonstrates a relatively large, rounded mass postero-laterally to the vertebral body. These lesions are isointense relative to the intervertebral disc on T1-weighted images and homogeneously hyperintense on T2. A gadolinium -DTPA-enhanced MRI shows a rim-enhancing lesion. A discogram reveals leakage of the contrast medium into the mass.

The operative findings demonstrated encapsulated soft tissue masses which contained bloody fluid and small fragments of herniated disc tissue. The pathologic examinations revealed fibrous tissue with hemosiderin deposit in cyst wall and degenerative disc materials with inflammatory cell infiltration.

This type of lumbar spinal cyst has been recognized as spinal epidural hematoma in recent years. Wiltse suggested that epidural hematoma may result from tearing of fragile epidural veins due to acute disc disruption. However, MRI characteristics of hematoma are not identical with those with lumbar spinal cyst. It is more likely that the lesions showing the pattern of changes are herniated disc tissue accompanied by hemorrhage and inflammation. If hernial tissue is covered with some membranous susbtance, formation of cystic lesions is understandable. Hence, we hypothesize that lesions, in which lysis liquefaction and absorption of the herniated disc tissue associated with inflammatory response have progressed, and the herniated disc tissue has completely disappeared, may be filled solely with bloody fluid, showing an appearance like cysts.

The purpose of this study is to clarify optimal timing of anterior cruciate ligament (ACL) reconstruction from the point of view of meniscus injury.

One hundred thirty-five ACL injuries (under 40 years of age) were analyzed in this study. All knees had undergone primary reconstruction without other ligament injury, and follow-up arthroscopy. ACL reconstruction was performed by the semitendinosus and gracilis method. The rehabilitation protocol was based on that of Shelbourne. Cases were divided into 4 groups by the period from injury to reconstruction. Nineteen knees were of the acute phase, which is within 1 month from the injury to reconstruction. Thirty-one knees were of the subacute phase, which is from 1 month over to reconstruction. Thirty-one knees were of the subacute phase, which is from 1 month over to 3 months from the injury to reconstruction. Forty knees were of the subchronic phase, which is from 3 months over to 1 year from the injury to reconstruction. Forty-five knees were of the chronic phase, which is over 1 year from the injury to reconstruction. We compared arthroscopic findings as well as clinical follow-up results of each phase.

The rate of lateral meniscus injury were 84% in the acute phase, 39% in the subacute phase, 58% in the subchronic phase, and 51% in the chronic phase. The rates of medial meniscus injury were 32% in the acute phase, 29% in the subacute phase, 53% in the sub-chronic phase, and 60% in the chronic phase. Horizontal tear and degenerative tear of the lateral meniscus were increased with time. Osteoarthritic change at follow-up arthroscopy was observed 3 knees in the acute phase, 4 knees In the subacute phase, 8 knees In the subchronic phase, and 13 knees in the chronic phase. There was no difference between clinical results of our ACL reconstruction in the acute phase and chronic phase.

ACL reconstruction in the acute phase was the effective method for preventing secondary osteoarthritis after medial meniscus injury.

Purpose: To evaluate repair of articular cartilage.

Methods: Ten cases of ten knees (6 males and 4 females) were evaluated in the current study. Seven knees treated by osteochondral graft including six receiving mosaic plasty and one receiving Pasteurization. Four knees treated by periosteal graft. One knee received both mosaicplasty and periosteal graft. Mean patient age at surgery was 31 years old. Eight knees underwent follow-up MRI, 6 knees underwent follow-up arthroscopy, and 4 knees underwent needle biopsy after informed consent was obtained. The mean period from the surgery to final follow-up was 21 months. The mean period from surgery to follow-up arthroscopy was 10 months.

Results: Seven cases of osteochondral graft presented good regeneration of articular surface by MRI and arthroscopic examination. Two knees receiving mosaic plasty demonstrated regeneration of hyaline cartilage even between the gaps in mosaicplasty. However, the structure of hyaline cartilage differed from that of normal cartilage. Pasteurization in one case also demonstrated good regeneration of hyaline cartilage. One knee treated by periosteal graft demonstrated regeneration of hyaline cartilage. However, the graft area in another such knee was covered by fibrous tissue. One periosteal graft became detached 14 days after surgery. There were no cases showing ossification after periosteal graft.

Conclusion: Periosteal graft could cover a wide defect of articular surface. However, induction of cartilage was not good. Osteochondral graft is a sure method of repairing hyaline cartilage where there is a small defect in the articular surface. Our results from needle biopsy demonstrated hyaline cartilage in the gaps among mosaicplasty areas, but the structure of hyaline cartilage was not good. There is a risk of re-degeneration due to the poor structure of hyaline cartilage. Careful observation is needed in both periosteal graft and mosaic plasty cases.