Tensile test of pressureless-sintered silicon nitride at elevated temperature

Uniaxial tensile strength tests of pressureless sintered silicon nitride were carried out in air at temperatures ranging from room temperature up to 1600 C. Silicon nitrides containing Y2O3, Al2O3, Al2O3-MgO, or MgO-CeO2 additives were tested. The results show that the composition of the additive used influences the strength characteristics of the silicon nitride. The tensile strength rapidly decreased at temperatures above 1000 C for the materials containing MgO as the additive and above 1000 C for the material with Y2O3. When the temperature increased to as high as 1300 C, the strength decreased to about 10 percent of the room temperature strength in each case. Observations of the fracture origin and of the crack propagation on the fracture surfaces are discussed

Multicentre, prospective, open study to evaluate the safety and efficacy of hylan G-F 20 in knee osteoarthritis subjects presenting with pain following arthroscopic meniscectomy

The aim of the study was to evaluate the safety and efficacy of viscosupplementation with hylan G-F 20 in patients with mild to moderate osteoarthritis (OA) presenting with persistent knee pain 4–12 weeks after arthroscopic meniscectomy. A prospective, multi-centre, open study was carried out in patients with pain due to OA of the knee, not resolved by simple analgesics, 4–12 weeks after undergoing arthroscopic meniscectomy. To be eligible, patients had to score ≥50 mm and ≤90 mm on both walking pain and patient global assessment visual analogue scales (VAS; 0–100 mm) at baseline and be radiologically diagnosed pre-operatively with OA grade I or II on the Kellgren-Lawrence scale, with <50% joint space narrowing. Patients received three intra-articular, 2 ml injections of hylan G-F 20 in the target knee with an interval of 1 week between injections, and were followed for 52 weeks. The primary efficacy endpoint was the change from baseline in the walking pain VAS score at 26 weeks. Secondary outcome measures were the walking pain VAS scores at all other time points, the WOMAC Index at all time points, and patient and physician global assessment at all time points. The safety of the treatment was assessed using adverse event (AE) reports. A total of 62 patients (mean age 55.4 years, 52% male) were enrolled. The mean walking pain VAS score decreased by 36.8 mm from baseline at 26 weeks (P < 0.0001), and also showed statistically significant decreases (P < 0.0001) at all other time points. The change in WOMAC total and subscale scores from baseline were statistically significant (P < 0.0001) at all time points, as were the decreases in the physician and patient global assessment VAS scores. There were 18 target knee AEs (mostly pain and/or swelling and/or effusion) in 12 patients (19%) considered to be at least possibly related to treatment. The majority of these (78%) were mild or moderate in intensity. One patient (1.6%) experienced a serious adverse event (synovitis) in the target knee that was considered possibly related to study treatment. Hylan G-F 20 provides effective pain relief and improves stiffness and physical function in patients with mild to moderate OA presenting with persistent osteoarthritic pain 4–12 weeks after arthroscopic meniscectomy. Symptomatic efficacy was maximised at 12 weeks and maintained at 26 and 52 weeks. The type (pain and/or swelling and/or effusion) and the intensity (mostly mild/moderate) of AEs reported in this study are similar to those reported in other trials in different patient populations, but the incidence was higher (19%). The risk/benefit of hylan G-F 20 in this particular population of patients is favourable

Intraosseous foreign body granuloma in rotator cuff repair with bioabsorbable suture anchor

Biodegradable implants lead to problems such as cyst formation, soft-tissue inflammation, loose implant fragments or local osteolysis. This report represents the first published case of an intraosseous foreign body granuloma in the humeral head after arthroscopic rotator cuff tear fixation with a poly-l-lactide (PLLA) suture anchor. A 48-year-old female patient presented with pain in her right shoulder. A refixation of her right supraspinatus tendon with a biodegradable suture anchor was performed 11 months ago at an external hospital. Laboratory tests showed normal values for C-reactive protein, leukocytes and the erythrocyte sedimentation rate. No signs of infection or instability were noted. The visual analogue scale (VAS) was 8, the simple shoulder test (SST) was 4 and the American shoulder and elbow surgeons score (ASES) was 44. Plain radiographs showed high lucency in the area of the tuberculum majus. MRI showed an intra- and extraosseous mass surrounded by fluid in this area. Surgical care involved arthroscopic debridement and removal of the suture anchor. Histological examination revealed a foreign body granuloma. At the 18-month follow-up the patient was nearly pain-free. The VAS was 2, SST was 10 and ASES was 88. Foreign body granulomas are a well known but rarely described complication that arises after the use of biodegradable suture anchors in shoulder surgery. Every patient presenting with shoulder pain after usage of a biodegradable fixation material should be evaluated closely. Orthopaedic surgeons should be aware of the possibility of delayed foreign body reactions, especially after using PLLA anchors

Effect of dynamic compressive loading and its combination with a growth factor on the chondrocytic phenotype of 3-dimensional scaffold-embedded chondrocytes

Background and purpose Three-dimensionally (3D-) embedded chondrocytes have been suggested to maintain the chondrocytic phenotype. Furthermore, mechanical stress and growth factors have been found to be capable of enhancing cell proliferation and ECM synthesis. We investigated the effect of mechanical loading and growth factors on reactivation of the 3D-embedded chondrocytes