Papers by Massimiliano Baleani
Applied sciences, Mar 14, 2024
Journal of Tissue Engineering and Regenerative Medicine, Aug 16, 2018
Nonunion treatment has a high rate of success, although recalcitrant nonunion may determine the n... more Nonunion treatment has a high rate of success, although recalcitrant nonunion may determine the need for amputation. Therefore, new treatment options are continuously investigated in order to further reduce the risk of nonunion recurrence. This study aimed to (i) develop a new large animal model for bone atrophic nonunion and (ii) compare the efficacy of demineralized bone matrix (DBM) and DBM in combination with mesenchymal stem cells (MSC) in the new nonunion model. The new model consists of a non-critical, full-thickness segmental defect created in the sheep tibia, stabilized by an intramedullary nail, and involves the creation of a locally impaired blood supply achieved through periosteum excision and electrocauterization of the stump ends. Six weeks after defect creation, lack of hard tissue callus and established nonunion was observed in all operated tibiae both by radiographic and clinical evaluation. Nonunion was treated with allogeneic DBM or autologous MSC cultivated on DBM particles (DBM+MSC) for one day before implantation. Twelve weeks after treatment, radiographic, microtomographic, histologic and histomorphometric analysis showed the formation of bone callus in DBM group, while the fracture healing appeared at an early stage in DBM+MSC group. Torsional strength and stiffness of the DBM group appeared higher than those of DBM+MSC group, although the differences were not statistically significant. In conclusion, a new sheep bone nonunion model resembling the complexity of the clinical condition was developed. DBM is an effective option for nonunion treatment, while MSC do not improve the healing process when cultivated on DBM particles before implantation.
Clinical Biomechanics, Oct 1, 2003
Objective. This study investigated the initial strength and failure mode of different rotator cuf... more Objective. This study investigated the initial strength and failure mode of different rotator cuff repair techniques. Background. Full or partial re-rupture of the repair is one of the main post-operative complications for rotator cuff repair. The rate of failure is strongly affected by the extension of the tear, increasing in case of large or massive tears up to 62%. Design. The study was planned to assess the three individual components of the tendon-to-bone repair (tendon grasping, suture knotting, suture-to-bone fixation) and to identify the best combinations in terms of mechanical strength to failure. The best combinations were tested to compare the mechanical behaviour of the entire repair and suggest potential improvements in the repair technique. Methods. Experimental tests were performed using sheep shoulders. Three tendon-grasping techniques, two suture knotting techniques, and the effect of bone augmentation with metallic plate and bone quality on suture-to-bone fixation were investigated. Results. This study assessed the mechanical behaviour of different repair components. The best combinations of the investigated techniques showed that the weakest link was the tendon-suture interface. More importantly, the compliance of the investigated repairs was large. Conclusions. The initial strength of the rotator cuff repair can be improved by changing the repair technique. Nevertheless, even a low physiological load stressing the repaired tendon may cause a gap formation at the tendon-bone interface without necessarily producing failure of the repair. Relevance Post-operative protection of the repaired rotator cuff from tension load is necessary to reduce the risk of delaying or preventing of the healing process.
Frontiers in Pediatrics, Aug 3, 2022
Intercalary reconstruction of long bones by massive allograft: Comparison of construct stability ... more Intercalary reconstruction of long bones by massive allograft: Comparison of construct stability ensured by three different host-graft junctions and two types of fixations in a synthetic femur model.
University of Bologna eBooks, 2004
Journal of Biomechanics, 2003
The cortical shell of the femoral neck plays a role in determining the overall neck strength. How... more The cortical shell of the femoral neck plays a role in determining the overall neck strength. However, there is a lack of knowledge about the mechanical properties of cortical tissue of the femoral neck due to challenges in implementing accurate testing protocols for the thin shell. Indeed, mechanical properties are commonly derived from mechanical testing performed on tissue samples extracted from the femoral diaphysis, i.e. assuming tissue homogeneity along the femur. The aim of this work was to set up a reliable methodology to determine mechanical properties of bone samples extracted from thin cortical shell of the femoral neck. A three-point bending test was used to determine elastic and post-elastic properties of cortical bone samples extracted from the inferior and superior femoral neck. An optical system was used to monitor the sample deflection. Accuracy was preliminarily evaluated by determining the elastic modulus of an aluminium alloy. A good intra-and inter-sample variability was found on determining aluminium elastic modulus: 1.6% and 3.6%, respectively. Additionally, aluminium elastic modulus value was underestimated by less than 1%. A pilot trial was performed on a human femoral neck to assess the procedure feasibility. A total of 22 samples were extracted from the inferior and superior femoral neck and successfully tested. Preliminary results suggest that mechanical properties of cortical bone tissue extracted from human femoral neck might be side dependent, the superior tissue seems to exhibit better mechanical properties than the inferior one, at least in terms of yield stress and maximum strain. This supposedly different mechanical competence must be further investigated. The proposed procedure makes it feasible to carry out such studies.
Journal of Biomechanics, Jul 1, 2008
Journal of Biomechanics, Sep 1, 2022
Orthopaedic Proceedings, Feb 21, 2018
Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional option... more Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset and implant stability. This option is widely used in our Region, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy. The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening. Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board. It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /liter). It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase.
PubMed, Sep 25, 2001
The study simulated implantation of a hip prosthesis stem in the femur. The cement mantle produce... more The study simulated implantation of a hip prosthesis stem in the femur. The cement mantle produced in vitro was observed under an optic microscope. A higher concentration of porosity in the cement mantle at the stem-cement interface was observed. By heating the stem to 45 degrees C and 55 degrees C the authors observed a reduction in porosity in the three surfaces examined: stem-cement interface, internal surface, and cement-pseudofemur interface. Heating of the stem causes a reduction in polymerization time and an increase in maximum temperature achieved during the polymerization process. A reduction in porosity at the stem-cement interface influenced bending strength of the specimens extracted from the mantle. A significant difference between resistance to flexion in the specimens produced with the stem at 55 degrees, and in those with the stem at 23 degrees C was observed.
PubMed, Jun 12, 2002
It was the purpose of the experimental study to use laboratory experience to verify the effective... more It was the purpose of the experimental study to use laboratory experience to verify the effectiveness of different methods used to repair the rotator cuff. The sheep was used as an animal model because its infraspinous tendon is the most similar to that in the human. Three static trials were conducted using Instron machines, comparing the repair systems used most by the same authors in their clinical work, the hold of the suturing wires with two different threading procedures in the bone tunnels and two types of knotting, and the breakage loading of the suturing wires in the two different miniplate systems. The authors conclude that tendinous anchoring must be entrusted to reinforced suturing systems (modified SCOI and Mason Allen), the threading of wires in pairs in a single bone tunnel makes surgery easier and shortens the amount of time required, with threading of wires similar to or better than threading with a single wire. There are no differences in breakage loading of the wire at the level of the holes in the two miniplates considered in this study.
Materials, Jan 25, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
PubMed, Jul 1, 1997
Two cementless hip arthroplasty models with a modular neck made titanium alloy were submitted to ... more Two cementless hip arthroplasty models with a modular neck made titanium alloy were submitted to cyclical loading in air, in physiological solution, and in a solution for accelerated corrosion tests in order to study the damage process of modular couplings. Thereafter, on one of the two models a series of tests were conducted in order to evaluate the quality of debris produced by the couplings. The parameters of testing adopted allow us to estimate the production of metallic debris observable in vivo with this type of prosthetic stem. The results show that the couplings of modular prostheses may be the source of metallic debris. The amount of debris produced depends on the geometry of the coupling and of the entire implant. Good planning and realization of the couplings, however, reduce the phenomenon that is negligible as compared to other potential sources of debris such as the surface of the stem or of the prosthetic head.
Journal of The Mechanical Behavior of Biomedical Materials, Dec 1, 2020
The cortical shell of the femoral neck plays a role in determining the overall neck strength. How... more The cortical shell of the femoral neck plays a role in determining the overall neck strength. However, there is a lack of knowledge about the mechanical properties of cortical tissue of the femoral neck due to challenges in implementing accurate testing protocols for the thin shell. Indeed, mechanical properties are commonly derived from mechanical testing performed on tissue samples extracted from the femoral diaphysis, i.e. assuming tissue homogeneity along the femur. The aim of this work was to set up a reliable methodology to determine mechanical properties of bone samples extracted from thin cortical shell of the femoral neck. A three-point bending test was used to determine elastic and post-elastic properties of cortical bone samples extracted from the inferior and superior femoral neck. An optical system was used to monitor the sample deflection. Accuracy was preliminarily evaluated by determining the elastic modulus of an aluminium alloy. A good intra-and inter-sample variability was found on determining aluminium elastic modulus: 1.6% and 3.6%, respectively. Additionally, aluminium elastic modulus value was underestimated by less than 1%. A pilot trial was performed on a human femoral neck to assess the procedure feasibility. A total of 22 samples were extracted from the inferior and superior femoral neck and successfully tested. Preliminary results suggest that mechanical properties of cortical bone tissue extracted from human femoral neck might be side dependent, the superior tissue seems to exhibit better mechanical properties than the inferior one, at least in terms of yield stress and maximum strain. This supposedly different mechanical competence must be further investigated. The proposed procedure makes it feasible to carry out such studies.
The journal of bone and joint surgery, Mar 1, 2010
We investigated the effect of pre-heating a femoral component on the porosity and strength of bon... more We investigated the effect of pre-heating a femoral component on the porosity and strength of bone cement, with or without vacuum mixing used for total hip replacement. Cement mantles were moulded in a manner simulating clinical practice for cemented hip replacement. During polymerisation, the temperature was monitored. Specimens of cement extracted from the mantles underwent bending or fatigue tests, and were examined for porosity. Pre-heating the stem alone significantly increased the mean temperature values measured within the mantle (+14.2°C) (p < 0.001) and reduced the mean curing time (-1.5 min) (p < 0.001). The addition of vacuum mixing modulated the mean rise in the temperature of polymerisation to 11°C and reduced the mean duration of the process by one minute and 50 seconds (p = 0.01 and p < 0.001, respectively). In all cases, the maximum temperature values measured in the mould simulating the femur were < 50°C. The mixing technique and pre-heating the stem slightly increased the static mechanical strength of bone cement. However, the fatigue life of the cement was improved by both vacuum mixing and pre-heating the stem, but was most marked (+ 280°C) when these methods were combined. Pre-heating the stem appears to be an effective way of improving the quality of the cement mantle, which might enhance the long-term performance of bone cement, especially when combined with vacuum mixing.
Proceedings Of The Institution Of Mechanical Engineers, Part H: Journal Of Engineering In Medicine, Jul 30, 2009
The hardness of cortical human bone has been measured on osteons in different conditions. However... more The hardness of cortical human bone has been measured on osteons in different conditions. However, no data are reported in the literature regarding the effect of cortical tissue condition and indentation location on the measured hardness values. This study aimed to investigate whether the hardness of the human cortical bone evaluated by micro-indentation is influenced, first, by the tissue condition and, second, by the distance of the indentation from the edge of the Haversian canal. Two femura were collected from a subject without musculoskeletal disease. The Vickers hardness was measured by means of microindentation (applied load, 100 gf) on osteons with a cross-section greater than 200 μm. The tests were performed on wet and embedded tissue at different distances from the Haversian canal edge (30—150 μm). No significant differences were found in hardness values between the two contralateral femura. Embedded tissue was significantly harder (12 per cent) than wet tissue. No significant differences were found in hardness values measured at different distances from the Haversian canal edge except for those closer than 60 μm. Therefore, indentations cannot be performed on osteons small in cross-section, since the distance from the closer pore has to be controlled. They should be performed on wet tissue, to avoid an offset in the measured hardness.
Proceedings Of The Institution Of Mechanical Engineers, Part H: Journal Of Engineering In Medicine, Feb 1, 2003
The standardized femur is the computer aided design (CAD) solid model of a synthetic human femur,... more The standardized femur is the computer aided design (CAD) solid model of a synthetic human femur, commonly used in experiments in vitro, available in the public domain through the International Society of Biomechanics Finite Element Mesh Repository. Currently used by hundreds of researchers, it was made available to simplify the experimental cross-validation of numerical studies as well as their replication by other researchers. One aspect that the standardized femur left uncovered is the definition of muscles and ligaments. In particular, for a variety of simulations it would be extremely useful to map on to the femoral surface the insertion of the principal muscles. The aim of the present study was to create a new solid model, called the muscle standardized femur, where the femoral insertion of each muscle is mapped on to the surface of the femur. Published data on muscle insertion morphometry were registered to the model by applying an affine scaling defined on bone landmarks. Good agreement was found with another similar study in which only the insertion centres were defined. The new model will be made available in the public domain for no-profit uses. When combined with published data on the direction and intensity of muscular forces this model is expected to make a useful contribution to the steadily growing library of models and data sets made available to the biomechanical community.
Journal of The Mechanical Behavior of Biomedical Materials, Apr 1, 2023
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Papers by Massimiliano Baleani