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PubMed1979

Prosthetic resurfacing of the patella.

Accumulated data from many sources seem to indicate that prosthetic resurfacing of the patella may be an acceptable alternative to patellectomy in the treatment of chondromalacia patellae or patellofemoral arthrosis. A patellar prosthesis which is made of cobalt-chromium alloy is attached to a remnant of the original patella by means of the acrylic cement, polymethyl methacrylate. An analysis fo the results of the use of this prosthesis in 14 knees of 13 patients reveals excellent or good results in 13 cases and one poor result. The longest follow-up period was 2 years and 9 months and the shortest was 6 weeks. Based on current experience and the experience of others, prosthetic resurfacing of the patella may give the patient some years of pain-free patellofemoral function. This is especially true in patients with poor quadriceps reserve in whom the lever-arm distance of the extensor torque should be maiwtained. Until the ideal resurfacing material is developed, the use of presently available patellar prostheses with or without femoral prosthetic components, is recommended for further investigation.

Adolescent↗

PubMed1978

Impact characteristics of articular cartilage.

A rigid l m high stainless steel drop tower employing linear bearings has been used to study the impact characteristics of human articular cartilage. Instrumentation included a specially designed optoelctronic position transducer, piezoelectric force transducer, and high speed storage oscilloscope. Forty-eight 9 mm diameter samples of living articular cartilage and subchondral bone from the tibial plateaus of 4 human donors have been impacted at strains from 10 to 50%, and strain rates of 500s-1 and 1000 s-1. The integral bone/cartilage samples were mounted in polymethyl methacrylate for testing. Bone and cement impact characteristics have been studied separately. Stress, strain, and energy absorption data have been assembled for all the samples. Chondrocyte viability subsequent to impact has been investigated with the use of tritum labeled proline and autoradiography. Viability has been studied in relation to both the mechanical data and structural damage.

Autoradiography↗

PubMed1978

Experimental fracture healing: evaluation using radionuclide bone imaging: concise communication.

Radionuclide bone imaging was performed in a rabbit model to observe the course of fracture healing and to establish criteria for distinguishing nonunion and delayed healing from normal healing. Sequential gamma-camera images (with pinhole collimator) were collected and subjected to computer analysis. Five groups were established: a) control--immobilization; b) control--immobilization plus periosteal stripping; c) simple fracture--osteotomy; d) delayed union--osteotomy plus periosteal stripping; and e) nonunion--osteotomy, periosteal stripping and polymethyl methacrylate interposed between fracture fragments. Histographic representation of absolute count rates along rabbit tibias followed a predictable pattern in the simple-fracture and delayed-union groups. They differed only in the time of appearance of phases. The nonunion group demonstrated no recognizable sequential pattern. In this experimental model, serial bone scanning with quantitative data analysis has shown potential for indicating the course of healing in fractures and for serving as a guide to treatment.

Animals↗

PubMed1977

[Investigations of the final settling of implanted hip-joints by use of 85Sr (author's transl)].

Up to 8 years after replacement of hip-joints in 26 patients the strontium-85-uptake over both thighs was followed scintimetrically. In contrary to normal healing of fractures, this uptake became normal on the side of the operation not earlier than the end of the 2nd year after operation. One cause of this delay could be the continuing liberation of monomeres of polymethyl-methacrylates at the bed of the implant. It is important to consider the clinical signs on the opposite side, since there a raised strontium-85-uptake could produce a "pseudo"-diminished ratio between the two sides.

Aged↗

PubMed2026

Integrated experimental and bioinformatics analysis reveals ECM-integrin and redox signaling associated with PMMA/NiO nanocomposites for craniofacial applications.

BACKGROUND: Poly(methyl methacrylate) (PMMA) is widely used in dental and craniofacial applications; however, its clinical performance is limited by poor surface wettability, moderate mechanical strength, and restricted biological activity. Integrating nanomaterial engineering with computational biology offers an opportunity to better understand biomaterial-cell interactions and support the rational design of functional biomaterials. METHODS: Nickel oxide (NiO) nanoparticles were synthesized via chemical precipitation and incorporated into PMMA to fabricate nanocomposites. Physicochemical characterization included contact angle measurements, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Vickers hardness testing. Biocompatibility was evaluated using zebrafish embryo developmental assays. To explore biological processes potentially associated with biomaterial-cell interactions, bioinformatics analyses including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and STRING protein-protein interaction (PPI) network analyses were performed. RESULTS: Incorporation of NiO nanoparticles improved the surface and mechanical properties of PMMA, reducing the contact angle from 105.35° to 90.46° and increasing Vickers hardness compared with unmodified PMMA. Structural and morphological analyses confirmed successful synthesis and homogeneous nanoparticle incorporation. Zebrafish embryo studies demonstrated minimal developmental toxicity, supporting the biocompatibility of the nanocomposite. Bioinformatics analyses identified significant enrichment of pathways related to extracellular matrix organization, cell adhesion, focal adhesion, PI3K-Akt signaling, and oxidative stress regulation. Protein-protein interaction analysis revealed highly interconnected networks associated with ECM-integrin signaling and redox homeostasis, highlighting biological processes potentially associated with biomaterial-cell communication. CONCLUSIONS: PMMA/NiO nanocomposites exhibited improved physicochemical performance and favorable biocompatibility characteristics. The integration of experimental characterization with bioinformatics and network-based analyses provides a systems-level perspective on biomaterial-associated cellular processes and identifies ECM-integrin signaling and oxidative stress-related pathways as candidate biological processes for future experimental validation. These findings support the continued development of PMMA/NiO nanocomposites for oral and craniofacial biomedical applications.

Nanocomposites↗