Ten-year follow-up of a cemented tapered stem.

INTRODUCTION: This stem was cleared by the FDA in 2002 and has been implanted in cementless and cemented versions. Despite its long history, there are no long-term clinical  results available for the cemented version of this implant. The aim of this study was to provide such data. It was hypothesized that this implant delivers clinical success comparable to other tapered cemented stems. MATERIALS AND METHODS: A total of 113 hip replacements were performed in 106 patients between October 2007 and December 2009 using the cemented version of this stem. The mean age of the patients at operation was 74.8 years (range 50-91 years). The mean follow-up was 8.9 years with only two patients lost to follow-up. Implant survival was determined using the Kaplan-Meier analysis. RESULTS: Stem survival with revision for any reason as the endpoint was 96.4% after 10 years. Survival for stem aseptic loosening was 100%. There were no cases of osteolysis. Clinical outcomes, as shown by Harris Hip Scores, were in line with previous investigations and the rate of adverse events was very low. CONCLUSIONS: This is a modern cemented stem with an excellent survival rate and satisfactory functional outcomes. In this cohort, there were no failures related to the stem through the first decade.

Influence of cyclical mechanical loading on osteogenic markers in an osteoblast-fibroblast co-culture in vitro: tendon-to-bone interface in anterior cruciate ligament reconstruction.

PURPOSE: We aimed to evaluate the influence of cyclical mechanical loading on osteoblasts and fibroblasts, and co-cultures of both in vitro, simulating the conditions of the tendon-to-bone interface in anterior cruciate ligament reconstruction. METHODS: Osteoblast-like cells (OBL) and tendon-derived rodent fibroblasts (TDF) were cultured alone or in co-culture to simulate the tendon-to-bone interface. Cyclical loading was applied for one hour twice a day for three days, with a frequency of 1 Hz and 3 % strain. Alkaline phosphatase (AP), osteocalcin (OC), collagen type 1 (COL1A1), and bone morphogenetic protein 2 (BMP-2) gene expression and protein deposition were detected by real-time polymerase chain reaction (qPCR) and immunocytochemical analysis. RESULTS: Mechanical loading significantly decreased AP, OC, and COL1A1 gene expression in both OBL and TDF, compared to non-loaded culture. However, mechanical load increased gene expression of the same marker genes including BMP-2 during co-culture. Immunocytochemistry demonstrated increased deposition of corresponding proteins in the same range, independent of culture conditions. Higher depositions of BMP-2 were shown under loading conditions for osteoblast and TDF monocultures. Prolongation of mechanical loading resulted in cell detachment and spheroid formation. CONCLUSION: Cyclical mechanical loading caused downregulation of genes involved in osteointegration and osteoinduction, such as OC, ALP, and COL1A1 in monocultures of osteoblasts and fibroblasts; co-cultures lacked this phenomenon. Immunocytochemistry and qPCR analysis showed slight upregulations of marker genes and corresponding proteins. This might be due to the potential stabilising effects of osteoblast-fibroblast cross talk in the co-culture environment, simulating fibrocartilage formation at the tendon-to-bone interface.

Repair of a chondral defect using a cell free scaffold in a young patient--a case report of successful scaffold transformation and colonisation.

BACKGROUND: Chondral defects of the articular surface are a common condition that can lead to osteoarthritis if not treated. Therapy of this condition is a topic of constant debate and a variety of chondral repair strategies are currently used. One strategy involves implantation of a cell-free matrix of type I collagen (COL1), to provide a scaffold for chondrocyte migration and proliferation and extracellular matrix production. Although several studies have suggested that chondrocytes can move, to the best of our knowledge there is still no proof of chondrocyte occurrence in a former cell-free scaffold for articular cartilage repair in humans. CASE PRESENTATION: An 18-year-old male patient underwent arthroscopic surgery of the knee for patellar instability and a chondral defect of the femoral condyle. Clinical outcome scores were recorded pre-operatively, after 6 weeks and after 6, 12, 24 and 36 months. MRI was recorded after 6 weeks and after 6, 12, 24 and 36 months postoperatively. At 42 months after implantation of a cell-free type I collagen matrix and reconstruction of the medial patellofemoral ligament, the patient was again treated arthroscopically for a tear of the medial meniscus of the same knee. A biopsy of the previous chondral defect was taken during arthroscopy for histological examination. CONCLUSION: In addition to good clinical and radiological results reported for cell-free scaffolds for cartilage repair in several other studies, transformation of the scaffold could be observed during re-arthroscopy for the meniscal tear. Histological examination of the specimen revealed articular cartilage with vital chondrocytes and a strong staining reaction for type II collagen (COL II), but no reaction for type I collagen staining. This might indicate a complete transformation of the scaffold and supports the theory that cell free scaffolds could support cell migration. Although the cell source remains unclear, migrating chondrocytes from the periphery remain a possibility.