Total hip arthroplasty (THA) is one of the preferable solutions for regaining ambulatory activity for patients with end-stage osteoarthritis, and the procedure is well developed technically and large numbers of patients benefit from THA worldwide. However, despite the improvements in implant designs and surgical techniques, revision rates remain high, and the number of revisions is expected to increase in the future as a result of the increase in the volume of primary THA and the increase in the proportion of younger, more active patients who are likely to survive longer than their prosthetic implants. In revision THA, associated loss of bone stock in the acetabulum presents one of the major challenges. The aim of the present study was to analyze the clinical and radiographic outcomes and Kaplan-Meier survivorship of patients underwent revision surgeries of the acetabular cup sustaining aseptic loosening. We reviewed consecutive 101 patients (120 hips; 10 men 11 hips; 91 women 109 hips; age at surgery, 66 years, range, 45–85) who underwent acetabular component revision surgery, at a follow-up period of 14.6 years (range, 10–30). For the evaluation of the state of the acebtabulum, acetabular bony defects were classified according to the classification of the AAOS based on the intraoperative findings as follows; type I [segmental deficiencies] in 24 hips, type II [cavity deficiency] in 48 hips, type III [combined deficiency] in 46, and type IV [pelvic discontinuity] in 2. Basically, we used the implant for acetabular revision surgery that cement or cementless cups were for the AAOS type I acetabular defects, cementless cup, or cemented cup with reinforcement device were for type II, cemented cup with reinforcement device were for type III. Follow-up examination revealed that Harris Hip score improved from 42.5±7.8 points before surgery to 76±16.2 points (p<0.05). The survival rates of the acetabular revision surgery with cemented cups, cementless cups, and cemented cups with reinforcement devices were 65.1%, 72.8%, and 79.8%, respectively, however, there was no significant differences between the groups. There were nine cases, which failed in the early stage in the groups of cementless cups and cemented cups with reinforcement devices, because of the instability of the cementless cups or breakage of reinforcement plates caused by inadequate bone grafting. We conclude that the usage of the cementless cups for type I and II acetabular bony defects, and the cemented cups with reinforcement devices for type III bony defects will demonstrate durable long-term fixation in case of adequate contact between acetabular components and host-bone with restoration of bone stock by impaction bone grafting.

Purpose: The inflammatory response around herniated tissue in the epidural space is believed to play a major role in the spontaneous regression of herniated lumbar disc. Numerous macrophages invade the herniated tissue along with newly formed blood vessels which influence oxygen gradient. Inflammatory cytokines such as interleukin-1 are produced by macrophages. These chemical mediators could stimulate disc cells to produce proteases such as MMPs which degrade the intervertebral disc matrix and could hence influence regression of the herniation. Here we have examined the influence of IL-1β and oxygen tension on proteoglycan turnover using a three-dimensional disc-cell culture system.

Methods: Cells were isolated from the nucleus pulposus of 18–24 month bovine caudal discs by enzyme digestion. They were initially cultured for 14 days in alginate beads in DMEM containing 6% FBS at 4.10⁶ cells/ml under 21% oxygen to accumulate matrix. They were then cultured for 6 days under 0% or 21% oxygen and with or without IL-1β. Glycosaminoglycan (GAG) accumulation (as a measure of proteoglycan content) was measured using a DMB assay. Lactate and glucose production were measured using a standard enzymatic method. Rates of sulfated GAG synthesis was measured from rates of ³⁵S-sulfate accumulation. MMP activity was measured using coumarin fluorescent assay.

Results: The results showed that IL-1β had a significant effect on GAG accumulation and production and that its effect was dependent on oxygen tension. GAG production and sulfate incorporation rates decreased in the presence of IL-1β at high oxygen but low oxygen inhibited the effects of this cytokine. MMP activity increased with IL-1β under 21% oxygen, but not at low oxygen.

Conclusion: Exogenous IL-1β can activate MMP activity and digest the extracellular matrix of the disc but only at high oxygen tensions. Angiogenesis as well as inflammation is thus required for resorption of herniations.

Purpose: Proteoglycan loss is one of the first signs of disc degeneration. There is increasing interest in developing biological methods for its replacement both by in vivo repair and through tissue engineered constructs. Many factors influence the rate of proteoglycan accumulation. In this study, we examine how physiological levels of extracellular osmolality and oxygen tension influence proteoglycan accumulation in nucleus pulposus cells in a three-dimensional culture system.

Methods: Cells were isolated from the nucleus pulposus of 18–24 month bovine caudal discs. They were cultured for 6 days in alginate beads at 4 million cells/ml in DMEM containing 6% FBS under 0%, 5% and 21% O₂, Medium osmolality was altered by NaCl addition over the range 270–570 mOsm. Cell viability was determined by manual counting using trypan blue. Lactate production was measured enzymatically and glycosaminoglycan (GAG) accumulation was measured using a DMB assay.

Results: There was no difference in the cell viability. Lactate production decreased under hypo- (270 mOsm) after 6 days in culture. After 6 days GAG accumulation was maximal in beads cultured at 5% O₂ in 370 mOsm where GAG accumulation was 86.1% greater than at 21% O₂ and DMEM at standard Osmolarity (270 mOsm).

CONCLUSION: In our model the prevailing osmolality was a powerful regulator of GAG accumulation by cultured nucleus cells. In vivo prevailing osmolality is governed by GAG concentration. These results thus indicate GAG synthesis rates are regulated by GAG concentration, with implications both for the aetiology of degeneration and for tissue engineering.

Fit with the proximal femoral cortices is critical to the success of cementless femoral stems in total hip arthroplasty. Conventional femoral stems are often designed from the average geometry of the normal femora. Hip disease in Japan, however are predominantly associated with Osteoarthritis secondary to congenital hip dislocation or sublux-ation of the hip. We developed a new model of proximal fitting cementless total hip stem, the so-called FMS (for Fukui Medical School) stem, based on the endosteal geometry of Japanese proximal femoral canal with developmental dysplasia of the hip. The proximal third surface of this stem model was circumferentially hydroxyapatite-coated.

One hundred-two hips in 85 patients underwent cement-less total hip arthroplasty with the new stems were studied with a minimum follow-up period of two years. There were 78 women and 8 men, and the mean age of the patient at the time of operation was 56.4 years. Preoperative diagnosis was developmental dysplasia of the hip in 94 hips, osteonecrosis in 6 hips and rheumatoid arthritis in 2 hips. The mean follow-up period was 43 months (24 to 74). Clinically, the mean Harris Hip Score was 48 points preoperatively, which improved to 92 points at the latest follow-up. Thigh pain was present in two hips (2%) at the latest follow-up although in six hips (6%) in the study group at one-year follow-up. Radiographically, according to Engh’s criteria, spot welds associated with osseointegration were observed around the inferior border of the proximal coating in all hips. We have observed no loosening or failure of the stems at the latest follow-up. Our results indicate that the new model of proximal fitting cementless fem