Bone defects created after curettage of benign bone tumors are customarily filled with solid poly(methyl methacrylate) (PMMA) or other bone substitutes. In this study, we depicted a porous PMMA-based cement (produced by mixing sodium bicarbonate and citric acid) and evaluated the prospect of its clinic application. Cement samples were characterized by high-performance liquid chromatography (HPLC) coupled to mass spectrometry and its cytotoxicity evaluated in fibroblast cultures. Implantation in rabbits allowed the histologic analysis of bone, kidneys, and liver for toxicity and coagulation tests, and MRI images for hemostasis evaluation. Osseointegration was analyzed through radiography, microtomography (micro-CT), SEM, and histology of sheep specimens. Rabbit specimens were analyzed 1, 4, and 7 days after implantation of porous or solid bone cement in 6.0 mm femoral defects. Sheep specimens were analyzed 3 and 6 months after implantation or not of porous or solid cement in 15.0 mm subchondral tibial defects. The production process did not release any detectable toxic substance but slightly reduced fibroblast proliferation in vitro. Until 7 days after surgery, no local or systemic alterations could be detected in histology, or hematoma formation in histology or MRI. Sheep implants showed 6 mm linear ingrowth from the bone-cement interface and 20% bone ingrowth considering the whole defect area. Radiography, micro-CT, SEM, and histology confirmed these findings. We conclude that our porous PMMA-based cement is an attractive alternative treatment for bone defect filling that combines osseointegration and early weight bearing. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 649-658, 2018.

OBJECTIVE: Macroporous cement with mechanical properties similar to cancellous bone may improve the treatment of large bone defects in relation to solid acrylic cement. The aim of this study was to compare physical and mechanical characteristics of a polymethyl methacrylate (PMMA) based porous cement with cancellous bone. METHODS: Compressive strength and pore size, interconnectivity, and distribution of cylindrical porous PMMA cement samples containing 10% (G1), 20% (G2) or 30% (G3) effervescent components were analyzed. Results were compared to bovine cancellous bone (G4) and solid PMMA (G5) samples. RESULTS: Scanning electron microscopy (SEM) of all experimental samples (G1 - G3) revealed a random distribution and a wide size variation of pores ranging from 50 µm to 3 mm. Micro-CT showed that G2 have high porosity and lower interconnectivity of pores. No significant differences in yield strength and Young's modulus were observed among G1, G2 and G3. G4 samples were slightly stronger and less elastic than the other groups. Solid PMMA is extremely strong and inelastic. CONCLUSIONS: PMMA based porous cement met the expected characteristics. High porosity with large and interconnected pores may allow for bone ingrowth. Strength and elasticity similar to cancellous bone may enhance mechanical stimuli to bone remodeling. Observational Descriptive Study.

CIMATTI, BRUNO. Development and characterization of a cancellous cement repair of bone defects. Morphometric analisys and mechanical testing. 2012. 107 p.

Introduction: Movement of the forearm allows positioning the hand during several functional activities of daily living. Assessing range of motion of supination and pronation is essential for clinical identification of functional limitations, although many methods can be used. Confounding values can be found due to different techniques used by therapists. The purpose of this study was to compare two standard goniometric methods for measuring active range of motion of forearm pronation and supination, aiming to define its reliability and ease of use. Methods: The study included 33 individuals, 13 injured and 20 non-injured volunteers. We analyzed two standard goniometric methods for measuring pronation and supination. For the first method, the volunteers had to hold a pencil as a guide for the movable arm of the goniometer and for the second method the movable arm was in contact with the distal dorsal surface of the wrist near the ulna head, and the hand was free. Two trained examiners performed the evaluations. Intraclass correlation coefficient and limits of agreement of Bland and Altman were used to analyze the data. Results: Intraclass correlation coefficient values were excellent for both groups and movements at inter-rater and intermethods comparison. Bland and Altman plots showed that, although excellent reliability, some data dispersion was present. Conclusion: These data suggest that both methods could be used in clinical practice with excellent reliability. The goniometric method with the movable arm placed in contact with the distal dorsal surface of the wrist near the ulna head might be easier to perform and useful in cases where finger prehension is absent or weak, which would prevent the use of a pencil as reference.

Biomaterials’ structural characteristics and the addition of osteoinductors influence the osteointegration capacity of bone substitutes. This study aims to identify the characteristics of porous and resorbable bone substitutes that influence new bone formation. An Internet search for studies reporting new bone formation rates in bone defects filled with porous and resorbable substitutes was performed in duplicate using the PubMed, Web of Science, Scielo, and University of São Paulo Digital Library databases. Metaphyseal or calvarial bone defects 4 to 10 mm in diameter from various animal models were selected. New bone formation rates were collected from the histomorphometry or micro-CT data. The following variables were analyzed: animal model, bone region, defect diameter, follow-up time after implantation, basic substitute material, osteoinductor addition, pore size and porosity. Of 3,266 initially identified articles, 15 articles describing 32 experimental groups met the inclusion criteria. There were no differences between the groups in the experimental model characteristics, except for the follow-up time, which showed a very weak to moderate correlation with the rate of new bone formation. In terms of the biomaterial and structural characteristics, only porosity showed a significant influence on the rate of new bone formation. Higher porosity is related to higher new bone formation rates. The influence of other characteristics could not be identified, possibly due to the large variety of experimental models and methodologies used to estimate new bone formation rates. We suggest the inclusion of standard control groups in future experimental studies to compare biomaterials.