No abstract

The aim of this study was to determine the suitability of hybrid scaffolds composed of naturally derived biopolymer gels and macroporous poly-epsilon-caprolactone (PCL) scaffolds for neocartilage formation in vitro. Rabbit articular chondrocytes were seeded into PCL/HA (1 wt % hyaluronan), PCL/CS (0.5 wt % chitosan), PCL/F (1:3 fibrin sealant plus aprotinin), and PCL/COL1 (0.24% type I collagen) hybrids and cultured statically for up to 50 days. Growth characteristics were evaluated by histological analysis, scanning electron microscopy, and confocal laser scanning microscopy. Neocartilage was quantified using a dimethyl-methylene blue assay for sulfated glycosaminoglycans (sGAG) and an enzyme-linked immunosorbent assay for type II collagen (COL2), normalized to dsDNA content by fluorescent PicoGreen assay. Chondrocytes were homogenously distributed throughout the entire scaffold and exhibited a predominantly spheroidal shape 1 h after being seeded into scaffolds. Immunofluorescence depicted expanding proteoglycan deposition with time. The sGAG per dsDNA increased in all hybrids between days 25 and 50. PCL/HA scaffolds consistently promoted highest yields. In contrast, total sGAG and total COL2 decreased in all hybrids except PCL/CS, which favored increasing values and a significantly higher total COL2 at day 50. Overall, dsDNA content decreased significantly with time, and particularly between days 3 and 6. The PCL/HA hybrid displayed two proliferation peaks at days 3 and 25, and PCL/COL1 displayed one proliferation peak at day 12. The developed hybrids provided distinct short-term environments for implanted chondrocytes, with not all of them being explicitly beneficial (PCL/F, PCL/COL1). The PCL/HA and PCL/CS hybrids, however, promoted specific neocartilage formation and initial cell retention and are thus promising for cartilage tissue engineering.

We studied the occurrence and correlation between a rotator cuff tear and glenohumeral degeneration. 44 cadaveric shoulders (22 right) were obtained from 32 subjects (18 females), mean age 73 (62-86) years and without a history of systemic diseases. Rotator cuffs were exposed and tear size (14 shoulders) was measured after removal of soft tissue and deltoid. Articular cartilage damage of the glenoid and humeral head was recorded by photography. A grading system of 1 (intact), 2 (mild) and 3 (severe) was used to determine the severity of cartilage damage. The area of articular cartilage damage was calculated using the Sonic Digitizer Analyzing System. The area of articular cartilage damage to the glenoid and the humeral head in the rotator cuff tear group was 32% and 36%, respectively. It was greater than that in the groups without a tear, which was 6% in the glenoid and 7% in the humeral head. However, it was not correlated with the size of the tear. Most of the articular cartilage damage in massive and large rotator cuff tears was located in the anterior-inferior portion of the glenoid and in the posterior portion of the humeral head. The articular cartilage damage area of the glenoid was correlated with that of the humeral head. In conclusion, the area of glenohumeral degeneration was greater in the rotator cuff tear group and was located in a specific site. Reproduced with permission from Acta Orthopaedica Scandinavica. 74(1):89-94,

Quantitative information regarding the interface strength and degree of cement penetration associated with cement viscosity during total hip arthroplasty is limited. The aim of the present study was to determine the effect of the viscosity of bone cement at the time of implantation on the mechanical integrity of total hip arthroplasty. Cement that was injected at an early less viscous stage produced greater failure strength in a push-out test than its more viscous counterpart.