The purpose of this study was to investigate the chondrogenic potential of magnetically labeled synovium-derived cells (M-SDCs) and examine whether M-SDCs could repair the articular cartilage using an intra-articular magnet after delivery to the lesion. Synovium-derived cells (SDCs) were cultured from the synovium of a rat knee, and were magnetically labeled with ferumoxides. M-SDCs were examined with a transmission electron microscope. A pellet culture system was used to evaluate the chondrogenic potential of M-SDCs in a magnetic field. In a rat model, allogeneic M-SDCs were injected into the knee after we made an osteochondral defect on the patellar groove and implanted an intra-articular magnet at the bottom of the defect. We histologically examined the defects at 48 h, 4 weeks, 8 weeks, and 12 weeks after treatment. Electron microscopy showed the transfection of ferumoxides into SDCs. The pellet cultures revealed the chondrogenic potential of M-SDCs in a magnetic field. M-SDCs accumulated in the osteochondral defect at 48 h after treatment, and we confirmed the regeneration of the articular cartilage at 4 weeks, 8 weeks, and 12 weeks after treatment using an intra-articular magnet. We demonstrated that articular cartilage defects could be repaired using an intra-articular magnet and M-SDCs. We believe that this system will be useful to repair human articular cartilage defects. Keywords: cell delivery system; magnet; synovium; intra-articular injection; cartilage repair Articular cartilage is well known to have very limited self-healing potential. There are many procedures, including drilling, abrasion, microfracture, and distraction, for repairing the articular cartilage.1-7 However, the defects are repaired by fibrous tissues during those procedures, 6,8 and a routine procedure for articular cartilage defect repair has not yet been established.Currently, engineered cartilage tissues are in widespread clinical use, and good clinical results have been achieved with these tissues.9,10 However, this procedure requires the harvesting of a small amount of cartilage tissues from the patient prior to cartilage transplantation. It is therefore necessary to implement a lessinvasive procedure.Recently, synovium-derived cells (SDCs) have been found to have a high potential for both proliferation and differentiation.11-15 Synovial tissues are easy to harvest and may be collected from any joint without damaging the articular cartilage. We therefore evaluated the method of transplanting SDCs for repairing articular cartilage defects.Previous studies have suggested that intra-articular injected mesenchymal stem cells (MSCs) mobilize to the injured tissues. 16 This transplantation was less invasive, but was inefficient because the injected cells spread throughout the joint space. Consequently, we created an intra-articular magnet which had a strong magnetic force, for efficient transplantation. The delivered cells were magnetically labeled with ferumoxides, which is approved by the United States Food and Drug Admi...

Purpose The purpose of this study was to investigate the mid-term results of 32 acetabular reconstructions performed using a Kerboull-type acetabular reinforcement device and bone graft between June 1997 and January 2009. Methods The mean age of the patients at the time of surgery was 71.4 years (range 55-85). Patients were followed-up for a mean of 7.5 years (range 2.1-13.7). The acetabular bone defects according to the American Academy of Orthopaedic Surgeons system was type III for 29 hips and type IV for three hips. Bulk allografts were performed in 30 hips and morselised autografts (iliac bone) were performed in two hips. Clinical evaluations were made according to the criteria of Postel/Merle d'Aubigné. Results The mean pre-operative Postel/Merle d'Aubigné hip score was 7.0±2.9, and the final follow-up hip score was 12.6±2.8. Six hips showed radiographic loosening, and two hips required further revision. A Kaplan-Meier analysis showed that the five-year and ten-year survival rates were 96.9% and 92.3%, respectively, using further revision of the acetabular device as an end point. Conclusion Acetabular reconstruction using a Kerboulltype acetabular reinforcement device and bone graft gives satisfactory mid-term results.

Purpose The posterior approach is widely used in femoral hemiarthroplasty. The major problem with this approach is the high risk of postoperative dislocation. A modified posterior approach, the conjoined tendon preserving posterior approach (CPP), was developed to reduce postoperative dislocations. The objective of this multicenter study was to evaluate the efficacy and safety of hemiarthroplasty performed using the CPP approach for femoral neck fractures. Methods A total of 322 patients with femoral neck fracture, from 10 facilities, were prospectively studied. Bipolar hemiarthroplasty using the CPP approach was performed, using the same type of implants. Hip joint movement was not restricted following surgery, regardless of a patient’s cognitive status. Final follow-up was performed 9.1 ± 1.5 months after surgery. Results Hemiarthroplasty was undertaken in 320 patients using the CPP approach. The mean age, operative time, and intraoperative blood loss were 83.3 ± 7.4 years, 70.0 ± 22.7 min, and 134.8 ± 107.9 mL, respectively. No postoperative dislocations were observed during the study period. Intraoperative adverse events related to the hip joint included femoral fractures in five patients (1.6%) and trochanteric fractures in four patients (1.3%). Postoperative hip joint adverse events included a periprosthetic fracture in one patient (0.3%), deep infection in two patients (0.6%), and stem subsidence in one patient (0.3%). Postoperative deaths occurred in 23 patients (7.2%). One patient (0.3%) had a severe non-hip adverse event unrelated to surgery that prevented independent living, while five patients (1.6%) had a moderate non-hip adverse event that required treatment. Conclusion The CPP approach prevented postoperative dislocation following femoral hemiarthroplasty in elderly patients, with no CPP-associated specific adverse events.

Introduction The thrust plate hip prosthesis (TPP) is a bone-reserving prosthesis for cementless Wxation at the metaphysis of the proximal femur. We retrospectively evaluated the results of 162 patients (179 hips) who underwent hip arthroplasty using TPP. Patients and methods Eighty-three patients (87 hips) suVered from osteoarthritis of the hip joint (OA group), 79 patients (92 hips) from osteonecrosis of the femoral head (ON group). The mean age at surgery was 55 years in the OA group and 47.4 years in the ON group. The mean follow-up period was 97 months in the OA group and 104 months in the ON group. For these patients, we evaluated the results clinically and radiographically. Results The mean Merle d'Aubigne's score improved from 8.2 to 16.9 in the OA group and from 9.1 to 16.6 in the ON group at the Wnal follow-up. Early mechanical loosening of TPP was observed in two hips of OA and one hip of ON. In one patient of ON, bilateral TPPs had to be removed 5 years postoperatively because of infection. Two female patients with ON suVered from a spontaneous femoral fracture below the tip of the lateral plate. Kaplan-Meier survivorship using TPP removed for any reason as the end point was 97.7% in the OA group and 90.3% in the ON group after 13 years. ConclusionThe middle-term results of the TPP were satisfactory if the indication for the TPP and the operative procedure were appropriate. The TPP is a useful and safe prosthesis for relatively young patients with not only osteoarthritis of the hip but also osteonecrosis of the femoral head.

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