Gel casting of resorbable polymers. 2. In-vitro degradation of bone graft substitutes.

Gel cast microporous materials produced from: slow resorbing, poly(L-lactide); fast resorbing, 50:50 poly(DL lactide coglycolide); and blends of these polymers have been characterized by weight loss, compression testing and thermal analysis after immersion in phosphate buffered saline (37 degrees C, pH 7.4) for times up to 6 months. Increasing weight loss and reduction in compressive properties with immersion time were measured. Blending reduces the rate of weight loss and material shrinkage relative to the copolymer. Thermal analysis of degraded samples revealed evidence of reorganization of the crystalline phase in poly(L-lactide) and a crystalline component in the 50:50 copolymer, estimated at 5-7% of the original material content, which is probably responsible for gel formation. Thermograms of the blend are effectively a superposition of thermograms of the individual components. Gel casting shows potential for varying the resorption rate, form stability and compressive properties of micro/macroporous bone graft substitutes.

[1]  W. Enneking,et al.  Autogenous cortical bone grafts in the reconstruction of segmental skeletal defects. , 1980, The Journal of bone and joint surgery. American volume.

[2]  T. Yamamuro,et al.  Apatite-wollastonite containing glass ceramic-fibrin mixture as a bone defect filler. , 1988, Journal of biomedical materials research.

[3]  Y. Ikada,et al.  Polymer-hydroxyapatite composites for biodegradable bone fillers. , 1986, Biomaterials.

[4]  T. K. Hunt,et al.  Anaerobic metabolism and wound healing: an hypothesis for the initiation and cessation of collagen synthesis in wounds. , 1978, American journal of surgery.

[5]  E J Kuncir,et al.  Load-bearing characteristics of polyethylene foam: an examination of structural and compression properties. , 1990, Journal of rehabilitation research and development.

[6]  G. Wegner,et al.  Investigation of the structure of solution grown crystals of lactide copolymers by means of chemical reactions , 1973 .

[7]  J. W. Leenslag,et al.  Resorbable materials of poly(L‐lactide). V. Influence of secondary structure on the mechanical properties and hydrolyzability of poly(L‐lactide) fibers produced by a dry‐spinning method , 1984 .

[8]  A. Pennings,et al.  General crystallization behaviour of poly(l-lactic acid) , 1980 .

[9]  A. Schindler,et al.  Sustained drug delivery systems. I. The permeability of poly(ϵ-caprolactone), poly(DL-lactic acid), and their copolymers , 1979 .

[10]  J O Hollinger,et al.  Biodegradable bone repair materials. Synthetic polymers and ceramics. , 1986, Clinical orthopaedics and related research.

[11]  D. Cohn,et al.  Compositional and structural analysis of PELA biodegradable block copolymers degrading under in vitro conditions. , 1989, Biomaterials.

[12]  J O Hollinger,et al.  Preliminary report on the osteogenic potential of a biodegradable copolymer of polyactide (PLA) and polyglycolide (PGA). , 1983, Journal of biomedical materials research.

[13]  Michel Vert,et al.  Structure-property relationships in the case of the degradation of massive aliphatic poly-(α-hydroxy acids) in aqueous media , 1990 .

[14]  C. G. Pitt,et al.  The biodegradability of polyester blends. , 1990, Biomaterials.

[15]  A. M. Reed,et al.  Biodegradable polymers for use in surgery — poly(glycolic)/poly(Iactic acid) homo and copolymers: 2. In vitro degradation , 1981 .

[16]  C. Chu.  Hydrolytic degradation of polyglycolic acid: Tensile strength and crystallinity study , 1981 .

[17]  D E Cutright,et al.  The repair of fractures of the orbital floor using biodegradable polylactic acid. , 1972, Oral surgery, oral medicine, and oral pathology.

[18]  S. Gogolewski,et al.  BIODEGRADABLE MATERIALS OF POLYLACTIDES, .4. POROUS BIOMEDICAL MATERIALS BASED ON MIXTURES OF POLYLACTIDES AND POLYURETHANES , 1982 .

[19]  A. Schindler,et al.  Aliphatic polyesters. I. The degradation of poly(ϵ‐caprolactone) in vivo , 1981 .

[20]  G. Finerman,et al.  Repair of segmental defects of the tibia with cancellous bone grafts augmented with human bone morphogenetic protein. A preliminary report. , 1988, Clinical orthopaedics and related research.

[21]  J. Hollinger,et al.  A preliminary study of the osteogenic potential of a biodegradable alloplastic-osteoinductive alloimplant. , 1988, Clinical orthopaedics and related research.

[22]  G. Boering,et al.  Resorbable materials of poly(L-lactide). VII. In vivo and in vitro degradation. , 1987, Biomaterials.

[23]  D C Tunc,et al.  Body-absorbable osteosynthesis devices. , 1991, Clinical materials.

[24]  A. Pennings,et al.  Bio-absorbable plates and screws for internal fixation of mandibular fractures. A study in six dogs. , 1989, International journal of oral and maxillofacial surgery.

[25]  A. Coombes,et al.  Gel casting of resorbable polymers. 1. Processing and applications. , 1992, Biomaterials.

[26]  Ross R. Muth,et al.  Biodegradable polymers for use in surgery—polyglycolic/poly(actic acid) homo- and copolymers: 1 , 1979 .

[27]  D. Mears,et al.  The results of 39 fractures complicated by major segmental bone loss and/or leg length discrepancy. , 1984, The Journal of trauma.