AbstractThe aim of synovectomy combined with the Sauvé–Kapandji (S–K) procedure for the treatment of a rheumatoid wrist is to obtain a stable painless wrist that retains sufficient mobility for function. However, loss of motion occurs postoperatively in most cases. In our study of 59 rheumatoid patients, the results of the transposition of distal strips of retinaculum into the radiocarpal and ulnocarpal joints for interposition arthroplasty to maintain wrist motion (interposition group), and transposition below the extensors to provide a gliding surface (SK group) were evaluated. The distal end of the ulna was fixed to the radius with poly-L-lactic acid screws, and a proximal strip of retinaculum was placed above the extensors after synovectomy of the rheumatoid wrist. Clinical symptoms, radiographic changes, and postoperative complications were assessed 3–9 years (mean 5.9 years) postoperatively. Patients in the interposition group showed better postoperative results, including wrist motion, than those of patients in the SK group. Both procedures resulted in only minor complications such as superficial skin necrosis, hematoma, and superficial infection. We concluded that interpostion arthroplasty combined with the S–K procedure using a distal strip of retinaculum might be a safe and appropriate method for wrist reconstruction following synovectomy of a rheumatoid wrist. 相似文献
Crystalline morphology, lamellar assembly, spherulitic growth rate, and physical properties of poly(l ‐lactide acid) (PLLA) modified by a room‐temperature ionic liquid (IL), N‐alkyl‐substituted‐glycine ester [N,N‐dimethyl‐N‐propyl glycine ethyl ester (DMPGlyET)+] bis(fluoromethanesufonyl)imide [TFSI?], are investigated by using polarized optical microscopy, optical microscopy, differential scanning calorimetric, and atomic‐force microscopy. Thermal analyses and in situ microscopy characterization reveal the PLLA/IL mixture with upper‐critical‐solution‐temperature behavior. Crystalline morphology of PLLA is significantly changed by the addition of IL to display massive diversification of spherulites morphology which has never been reported before in neat PLLA or PLLA blends with polymers. The morphological change and diversifications in PLLA/IL mixture are associated with strong interactions between PLLA and IL, which impede the melt crystallization of PLLA and tend to form PLLA nuclei of various geometry shapes. In addition, neat PLLA is generally brittle with extensive crack formation during postcrystallization cooling process; however, with the addition of IL, cracks are reduced or diminished entirely, potentially to enhance the performance and properties of PLLA.
Electrospun fiber mesh has been a candidate for guided bone regeneration membrane. However, its poor mechanics property has been limited in clinical application. In this study, various star-shaped poly(ε-caprolactones) (PCLs) are successfully synthesized by ring-opening polymerization and mixed with poly(l-lactide) (PLLA) to be made into blended membranes through electrospinning. Their corresponding properties are evaluated including morphology, thermodynamics, mechanics, and cytotoxicity. The blended fibers show smooth surface and well-distributed structure, which have slight differences in morphology with the change of arm number of star-shaped PCL. Crystallization of the fibrous membrane is influenced by star-shaped PCLs. Glass temperature drops from 64.23 °C for pure PLLA membrane to 53.62–49 °C for the blended membranes. The membranous tensile strength is depended strongly on star-shaped PCLs. The tensile strength goes up with arm number increasing; on the contrary, at the same arm number, the mechanics strength decreases with molecular weight increasing. And the fibrous membrane containing 20 wt.% star-shaped PCL shows better mechanics property compared to the other membranes. The star-shaped PCL/PLLA fiber membrane is not cytotoxicity. 相似文献
In this study, a nano-fibrous PLLA scaffold reinforced by micro-scale chitosan fibers was fabricated using thermally-induced phase separation (TIPS). The morphology, porosity, mechanical performance and pH changes in in vitro degradation of the scaffold were also investigated. Results showed that the mechanical properties of the scaffold increased with the amount of chitosan fibers embedded, and the pH in in vitro degradation of the scaffold changed more slowly than that of the pure nano-fibrous PLLA scaffold without chitosan fibers. The new composite scaffold might be a very promising scaffold for tissue engineering. 相似文献
In this study, two different viscosity-average molecular weight (η = 4.0 and 7.8) poly(L-lactide) (PLLA) were synthesized by ring-opening polymerization and the poly(L-lactide)/hydroxyapatite composites (PLLA/HA) were prepared by blending HA particles (size range: 25-45 μm and Ca/P = 1.69) with a content of 10, 30, and 50 wt% in PLLA solution with further evaporation of the solvent. The plain PLLA polymers and PLLA/HA composites were compressionmolded and machined to yield 25×3×2 mm3 specimens. The molar mass of resulting specimens was decreased drastically due to the hydrolytic and thermal degradation of ester bonds. Scanning electron microscopy and thermal gravimetric results indicated that the compositions of HA in PLLA were well dispersed. With increasing HA content, the crystallinity of PLLA/HA composites are slightly increased due to the effect of HA as a nucleating agent. The dynamic mechanical analysis is useful in studying the viscoelastic behaviour of the PLLA/HA composites and no secondary relaxation was observed below the glass-to-rubber transition (60°C). The mechanical properties of the PLLA/HA composites were found to vary with HA content. Increased levels of HA resulted in increased bending modulus and strength. 相似文献
- The aim of this study was to evaluate the effect of various sterilization processes on the physical and mechanical properties of self-reinforced bioabsorbable fibres made out of polylactide (PLLA). The samples were sterilized using plasma, ethylene oxide (one and two cycles), gamma (25 kGy at room temperature, 25 kGy in dry ice, and 2 × 25 kGy at room temperature), and electron beam (15, 25, and 55 kGy) sterilization. The intrinsic viscosity, crystallinity, and mechanical properties (modulus of elasticity, yield strength, and ultimate tensile strength) were tested before and immediately after each sterilization treatment, as well as up to 30 weeks in vitro. Compared with unsterilized fibres, the intrinsic viscosity was markedly decreased after radiation sterilization (gamma and electron beam) and the loss in mechanical properties was accelerated during in vitro degradation. Plasma and ethylene oxide (one and two cycles) did not markedly alter the properties of the samples after sterilization or during in vitrodegradation. These data are important for determining the effect of various sterilization processes on the physical and mechanical properties of polylactidebased materials and can be used to predict how fast degradation of the mechanical properties of the self-reinforced PLLA will occur. They can also be used to tailor the degradation kinetics to optimize implant design. 相似文献