No abstract

Fibroblast growth factor (FGF) has been reported to increase the volume of callus in a fracture model of rats. There are, however, no reports of successful repair of segmental bony defects by application of an FGF solution. In this study, the effects of basic FGF on the repair of segmental bony defects in the rabbit femur were examined. Minipellet, a new drug delivery system using atelocollagen, was employed to ensure effective delivery of FGF. Segmental bony defects (10 mm in length) were created in the right femurs of 19 rabbits. In pilot studies, no defects of this size healed spontaneously within 6 weeks. Bones were stabilized with miniexternal fixators. Minipellets containing basic FGF were implanted between fragments so as to bridge the two fragments. The healing processes were monitored radiographically and studied histologically. In rabbits in which FGF was added to the defect site at doses of 1.4 microgram or higher, approximately 90% of the defects were filled with new bone and cartilage within 6 weeks after minipellet implantation. In rabbits receiving placebo minipellets, however, approximately 15% of the defects were filled by callus within 6 weeks. Furthermore, this callus did not change into mature bone. An injection of 2 microgram of FGF solution to bony defects had no effect on the repair of segmental bony defects. These findings suggest that FGF plays a role in the production of adequate volumes of callus particularly in the initial stages of fracture healing and that sustained local release enables FGF to be effective at a low dose. In summary, large segmental bony defects healed after insertion of low-dose FGF minipellets. An adequate dose of FGF and an appropriate delivery system are required for successful healing of large bony defects. These findings imply the potential value of FGF minipellets in clinical practice.

Background Although nasal carriage of MRSA has been identified as one of the risk factors for surgical site infection (SSI) with MRSA, there have been no reports of this in the orthopedics field.Methods This prospective observational cohort study included 2,423 consecutive patients who were admitted to our department over 26 months and who underwent orthopedic surgery. We examined the relationship between pre-existing nasal MRSA and subsequent occurrence of SSI with MRSA.Results 63 patients (2.6%) had a positive nasal MRSA culture. 15 patients (0.6%) developed SSI with MRSA. The occurrence of SSI with MRSA in nasal MRSA carriers was significantly higher than that in non-carriers (4 out of 63 (6.3%) vs. 11 out of 2,360 (0.5%); p < 0.001) (adjusted OR: 11; 95% CI: 3–37; p = 0.001).Interpretation We recommend appropriate treatment of patients who are nasal carriers of MRSA before orthopedic surgery.

No abstract

It has been reported that preparation of the flexion gap results in significant widening of the prepared extension gap in posterior stabilized (PS) total knee arthroplasty (TKA). To date, there is a paucity of data regarding cruciate ligament-retaining (CR) TKA. Changes in the extension gap caused by preparation of the flexion gap were measured in 42 varus osteoarthritic knees undergoing CR TKA. The extension gap was first prepared and then measured before and after preparation of the flexion gap. The extension gap increased significantly on both the medial and lateral sides (18.8-20.0 and 21.7-22.7 mm, respectively) (P < 0.01). Preparation of the flexion gap also resulted in significant widening of the extension gap on CR TKA. However, amount of extension gap increase in CR TKA was smaller than previous reports on PS TKA.

The difference in the acetabular component orientation between the two positions, which might be caused by the difference between intra- and postoperative pelvic orientation, should be considered during THA.

Polyethylene wear particles are one of the most important factors affecting the results of total hip arthroplasty (THA). To reduce wear generation and to achieve better long-term results of THA, highly crosslinked polyethylene (HXPE) has recently been introduced and come into wide use. Thus far, however, there have been no reports on in vivo analysis of HXPE wear particles. We isolated HXPE wear particles from periprosthetic tissue of a failed THA and analyzed using scanning electron microscope. The number of particles was 5.33 x 10(7) g(-1). Particle size (equivalent circle diameter) was 0.66 +/- 0.40 microm (mean +/- standard error). Aspect ratio and roundness were 1.37 +/- 0.26 and 1.44 +/- 0.67, respectively. All the particles were round shaped, and "fibrils" or "shreds" were not detected. Thus far, this was the first report on in vivo wear particle analysis of HXPE. HXPE generated less, smaller, and rounder particles, compared with the corresponding reported values for particles generated from conventional polyethylene. These characteristics might affect macrophage response, osteolysis, and long-term results of THA with HXPE.

UMIN Clinical Trials Registry, http://www.umin.ac.jp/ctr/, UMIN000001798.