Naoya Taki

Change in Pelvic Tilt Angle 2 to 4 Years After Total Hip Arthroplasty

The purpose of this study was to evaluate the change in pelvic tilt angle (PA) in the sagittal plane in the standing and supine positions for 2 to 4 years after total hip arthroplasty (THA). Anteroposterior pelvic radiographs of 21 male and 65 female patients were investigated before and after THA yearly over 2 to 4 years. Both the standing and supine PA significantly posteriorly tilted after THA. The difference in PA between the standing and supine positions (dPA) significantly increased after THA. Although the PA in the standing and supine positions plateaued 1 year after THA, the dPA gradually increased. In addition, the percentage of patients who showed a difference of more than 10° in dPA tended to increase yearly. In particular, elderly female patients who showed posterior tilt in PA in the standing or supine positions or a large dPA before THA tended to show a dPA of more than 10° after THA.

Simultaneous anterior cruciate ligament reconstruction and opening wedge high tibial osteotomy: Report of four cases.

Four patients, aged 37-50 years, with chronic anterior cruciate ligament (ACL) deficiency, medial compartment osteoarthritis and varus deformity, underwent simultaneous arthroscopic ACL reconstruction and opening wedge high tibial osteotomy using the TomoFix fixation device and hydroxyapatite wedges. The simultaneous procedure allowed our patients to perform a full weight-bearing exercise at 4 weeks after surgery. At device removal and concomitant second-look arthroscopy, all patients had either a cyclops-like lesion or partial tears at the point of contact between the reconstructed ACL and intercondylar notch. Therefore, subsequent notchplasty or re-notchplasty was required. Because of the small number of patients, the results should be considered preliminary. Given our findings of graft morbidity caused by the corrected postoperative alignment, adequate intercondylar notchplasty should be performed at the initial operation.

Spontaneous dislocation of a mobile-bearing polyethylene insert after posterior-stabilized rotating platform total knee arthroplasty: A case report

We describe a dislocation after Scorpio mobile-bearing total knee arthroplasty. This system is a rotating platform posterior-stabilized design and utilizes a single post as part of the metal tibial tray. Only one locking ring inside the socket of the polyethylene insert secures a tight connection with the post. Spontaneous dislocation between the polyethylene insert and the metal tray occurred at 22 months post surgery while rising from the supine position with slight knee flexion. Operative findings revealed failure of the locking ring and the original insert was replaced with a thicker insert. Our case and a duplicated saw bone model demonstrated that failure of the locking system resulted in the dislocation of the insert.

Osseointegration of porous titanium implants with and without electrochemically deposited DCPD coating in an ovine model

BackgroundUncemented fixation of components in joint arthroplasty is achieved primarily through de novo bone formation at the bone-implant interface and establishment of a biological and mechanical interlock. In order to enhance bone-implant integration osteoconductive coatings and the methods of application thereof are continuously being developed and applied to highly porous and roughened implant substrates. In this study the effects of an electrochemically-deposited dicalcium phosphate dihydrate (DCPD) coating of a porous substrate on implant osseointegration was assessed using a standard uncemented implant fixation model in sheep.MethodsPlasma sprayed titanium implants with and without a DCPD coating were inserted into defects drilled into the cancellous and cortical sites of the femur and tibia. Cancellous implants were inserted in a press-fit scenario whilst cortical implants were inserted in a line-to-line fit. Specimens were retrieved at 1, 2, 4, 8 and 12 weeks postoperatively. Interfacial shear-strength of the cortical sites was assessed using a push-out test, whilst bone ingrowth, ongrowth and remodelling were investigated using histologic and histomorphometric endpoints.ResultsDCPD coating significantly improved cancellous bone ingrowth at 4 weeks but had no significant effect on mechanical stability in cortical bone up to 12 weeks postoperatively. Whilst a significant reduction in cancellous bone ongrowth was observed from 4 to 12 weeks for the DCPD coating, no other statistically significant differences in ongrowth or ingrowth in either the cancellous or cortical sites were observed between TiPS and DCPD groups.ConclusionThe application of a DCPD coating to porous titanium substrates may improve the extent of cancellous bone ingrowth in the early postoperative phase following uncemented arthroplasty.

Medial versus lateral condyle bone mineral density ratios in a cross-sectional study: a potential marker for medial knee osteoarthritis severity.

To assess the association of bone mineral density (BMD) of the femoral and tibial condyles with knee pain and disease severity in women with symptomatic medial knee osteoarthritis (OA).

Relationship Between Low Bone Mineral Density and Varus Deformity in Postmenopausal Women with Knee Osteoarthritis

Objective. To assess the relationship between bone mineral density (BMD) and varus deformity arising from bone structural changes caused by knee osteoarthritis (OA) in postmenopausal women. Methods. This cross-sectional study involved 135 consecutive postmenopausal female patients who had varus knee OA and a Kellgren-Lawrence grade ≥ 2. Knee radiographs were obtained with the patient standing on one leg, and subjects were classified into 3 tertile groups according to femorotibial angle, which was taken as a measure of varus knee OA severity. We also measured the 3 subangles that make up the femorotibial angle, and focused on the varus inclination of the tibial plateau. BMD was measured in the lumbar spine, femoral neck, and medial and lateral tibial condyles using dual-energy X-ray absorptiometry. Differences between femorotibial angle tertile groups were assessed, and associations between femorotibial sub-angles and BMD values at various points were evaluated. Results. After adjustment for age and body mass index, there was no significant association between the varus inclination of the tibial plateau and lumbar spine BMD. A weak but statistically significant negative correlation existed between varus inclination of the tibial plateau and BMD at the ipsilateral proximal femur and lateral tibial condyle. Conclusion. Varus inclination of the tibial plateau was significantly more severe in the femorotibial angle tertile 3 group, and in patients with lower BMD in the ipsilateral lower limb. Varus knee OA may result not only from cartilage loss but also from structural changes of the bone.

Mid- term results of stryker® scorpio plus mobile bearing total knee arthroplasty

BackgroundThe mobile bearing knee system was introduced to lessen contact stress on the articular bearing surface and reduce polyethylene wear. The purpose of the current study was to investigate the mid-term results of patients undergoing total knee arthroplasties (TKAs) using Scorpio Plus Mobile Bearing Knee System (Stryker, Mahwah, NJ), and compare the outcomes between patients with osteoarthritis and osteonecrosis (OA·ON group) and patients with rheumatoid arthritis (RA group).MethodsEight males and 58 females were followed up for a period of 4.4- 7.6 years from June 1, 2003 to December 31, 2005. There were 53 knees with osteoarthritis, 17 knees with rheumatoid arthritis, and 6 knees with osteonecrosis. Clinical and radiographic follow- up was done using The Japanese Orthopedic Association knee rating score (JOA score) and Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System.ResultsWith regard to the JOA score, there was significant improvement in both groups. The postoperative range of motion was between 0.8°and 116.8° in OA·ON group, and between 0.0° and 113.7° in RA group. There were no significant differences with the radiographic evaluation between two groups. Spontaneous dislocation of a polyethylene insert occurred in one patient, and deep infection was occurred in one patient.ConclusionThere was significant improvement with regard to the clinical and radiographic results of patients undergoing TKAs using the model. The risk of polyethylene insert dislocation related to the mobile bearing TKA is a cause for concern.

Reproducibility of condylar twist angle measurement using computed tomography and axial radiography of the distal femur

INTRODUCTION It is essential to understand rotational alignment of the distal femur when performing total knee arthroplasty (TKA). Several rotational landmarks including condylar twist angle (CTA) are used for preoperative planning and during TKA. Axial radiography of the distal femur is used for measuring the CTA, and assessing rotational alignment in TKA. The aim of this study was to investigate the reliability and the reproducibility of the CTA using two different methods and evaluate if CTA differed between varus and valgus knees and between normal and osteoarthritic knees. MATERIALS AND METHODS CTA were obtained from 144 knees (77 patients) having total knee or hip arthroplasty using computed tomography (CT) and axial radiography. Subjects were divided into five groups based on femorotibial angle (FTA) and into four groups based on the severity of knee osteoarthritis. The intra-observer and inter-observer reliabilities of these methods and inter-method differences were evaluated. RESULTS The mean CTA was 7.02° with axial radiography, and 6.87° with CT images. There were no significant differences among the five FTA groups and among the four osteoarthritis groups. In total, intra-/inter-observer, and inter-method intraclass correlation coefficients were substantial or almost perfect in the scoring system of Landis et al. However, discrepancies ≥ 2° between the two methods were observed in more than 20% of knees. CONCLUSION The CTA should be reassessed by more than two observers or two methods for precise preoperative TKA planning in cases where it is difficult to identify the bony landmarks for CTA measurements. LEVEL OF EVIDENCE Level III.