Background

Frequency of primary total hip (THA) and total knee (TKA) arthroplasty procedures is increasing, with a subsequent rise in revision procedures. This study aims to describe timing and excess surgical mortality associated with revision THA and TKA compared to those on the waiting list.

We aimed to review the outcome of Agility total ankle replacements carried out in our institution between 2002 and 2006. Follow-up consisted of clinical and radiological review pre-operatively, then at 6 weeks, 6 and 12 months, and annually until 10 years post op. Clinical review included the American Orthopaedic Foot and Ankle Score, satisfaction and pain scores. Case notes were reviewed to determine intra and post-operative complications. 30 arthroplasties were performed in 30 consecutive patients. Pre-operative diagnosis was rheumatoid arthritis(16), primary osteoarthritis(12) and post-traumatic osteoarthritis(2). After a mean follow up of 6.2 years (1.4–10.1), 4 patients had died, and 22 out of the remaining 24 were available for follow-up. Intra operative complications included lateral malleoli fracture(3) and superficial peroneal nerve injury(2). Post operative complications included 1 early death, but this was not related to the surgical procedure. Two patients developed deep infections of the prosthesis. One underwent removal of the implant; the other is on long term oral antibiotic therapy. One patient had delayed union of the syndesmosis and six patients had non-union. On clinical assessment, patients' AOFAS scores improved from mean 40.4 pre-op to 83.5 post-op (p<0.001). Radiological assessment of the tibial component revealed 25 (93%) patients had lucency in at least one zone in the AP radiograph. We found a relatively high level of re-surgery and complications following Agility total ankle replacement. A 7% revision rate is much higher than would be tolerated in knee or hip arthroplasty, but compares favourably to other studies of TAR. Despite radiological features which suggest loosening, the high rate of re-surgery and complications; patients are generally satisfied with the procedure, reporting lower levels of pain and improved function. Overall we feel that the Agility ankle is an acceptable alternative to ankle arthrodesis, however patients need to be warned of the risk of re-surgery

Summary. Despite similar, early and massive death, hMSCs promote bone formation which was higher in orthotopic than ectopic site suggesting a trophic effect of hMSCs. Ectopic implantation is suitable to evaluate cell survival, but assessment of bone formation requires orthotopic implantation. Introduction. Tissue constructs containing mesenchymal stem cells (MSCs) are appealing strategies for repairing large segmental bone defects but they do not allow consistent bone healing and early and massive MSCs death was identified as a cause of failure. However, little is known about cell survival in the clinical micro-environment encountered during bone healing process, whereas ectopic evaluation is well documented. In vivo, luciferase-labelled human MSCs survival, within osteoconductive scaffold, was compared in orthotopic and ectopic locations, and bone formation ability of LF-hMSCs-Acropora constructs was evaluated. Interest and limits of each model were highlighted. Methods. Osteoconductive scaffold with or without LF-hMSCs were implanted either in a critical-segmental-femoral-bone defect stabilised by plate or subcutaneously in 44 mice. Cells survival was evaluated by serial bioluminescence imaging (BLI) and osteogenic capabilities by histology and microCT. Twenty mice were sacrificied 15 days after surgery for “short term” evaluation. The other mice were kept for 10 weeks after surgery for “long term” evaluation. Results. BLI provided evidence of fast and continuous cell death: 85% decrease of the BLI signal over the first 15 days in both location; less than 2% of the initial cell number were present in all constructs analyzed 30 days post-implantation and less than 1% of the initial cell number was present in all constructs analyzed 55 days post-implantation. By 2 weeks post implantation, the amount of newly formed bone was self-limited and was similar between ectopic and orhtotopic group, with or without cell. By 10 weeks post implantation, bone formation was significantly enhanced in the presence of LF-hMSC. The amount of newly formed bone in the cell-containing constructs groups was significantly higher than that observed in the scaffold alone groups. Most importantly, the amount of newly formed bone in cell-containing constructs implanted in orthotopic locations was significantly higher than that observed in the ectopic, cell-containing construct group. Conclusion. Corroborating previous ectopic studies, our results indicated that hMSCs promote bone formation despite early and massive cell death when loaded on ceramic scaffold. Interestingly, bone formation was higher in orthotopic than ectopic site despite a same survival pattern and a massive and early cell death, suggesting a trophic effect of hMSCs. Ectopic implantation of cell-containing constructs is suitable to evaluate cell survival, but assessment of bone formation ability requires orthotopic implantation