**9. Biological chamber and polytherapy**

autologuos growth factors [platelet-derived growth factor (PDGF), TGF-β1-β2, insulin-like growth factor type 1-2 (IGF1-2) and vascular endothelial growth factor (VEGF)] able to stimulate bone, cartilage, and soft tissues healing processes on the site of use. It is charac‐ terized by an elevate concentration of trombocytes able to degranulate releasing several growth factors and cytokines that can induce osteogenesis and angiogenesis with a chemo‐ tactic and mitogenic mechanism [39]. It can be obtained from autologous or heterologous blood. Depending from the procedure used to treat the withdrawal can be obtained final platelet concentration from 4 to 8 times higher from the initial situation. In a randomized study of 2007 on 60 long-bones non-union has been demonstrated a minor healing capabil‐

ities by the PRP (63.8%) both in comparison with BMP-7 than to the autograft [30].

tibial pilon non-union.

114 Advanced Techniques in Bone Regeneration

concentration >1500/cm<sup>3</sup>

kind of synthesis meaning used.

**•** Scaffold

**•** Mesenchymal stromal cells (MSCs)

The AGFs contained in the PRP, as clarified by preclinical and clinical data, are promoters of the cellular division (mitogenesis) nonspecific for the bone cells, unable to promote the differentiation of the mesenchymal cells and to induce the formation of new bone tissue. They seem to be not useful when used alone or in association with scaffold in treatment of

Studies based on cellular therapies are concentrated on a rare non-hematopoietic cells population, the MSCs, which are present in patient's bone marrow and can be increased in colture in an undifferentiated state [40, 41]. In addition to their pluripotent properties, the MSCs are considered osteogenic progenitor cells with demonstrated ability to repair bone defects [42]. Their concentration at bone marrow level, however, can result not ever elevated [43, 44]. The influence of this factor seems to be fundamental to the aim to obtain the healing, and there are clinical evidences that a better prognosis is obtained with a progenitor cells

problem, between these patient's bone marrow aspirate permit the mesenchymal stem cells concentration directly in the operatory room. Those new methods have demonstrated two big advantages: a reduction in costs respect to the in vitro expansion of the MSCs and a drastic decrease of the donor site morbidity compared to the traditional collection in open surgery of the iliac crest [44, 45]. The clinical use of the MSCs, especially if associated with

The osteoconduction mediated by the scaffold is determined by the chemical–physical characteristics of the substratum act to favor the adhesion and the growth of the cells on the surface. The mechanical characteristics of the bone graft, and their resistance to the com‐ pression and torsion, are influenced from their shape (massive, cortical splint, spongious block, morcellized), from the withdrawal modality, processing, conservation, and from the

The synthesis substitutes used are mineral structures similar to human bone kind. They have only osteoconductive power. Between synthesis substitutes you can find calcium phosphate as hydroxyapatite, coralline hydroxyapatite (absorbable), tricalcium phosphate (TCP, absorbable), and biphasic calcium phosphate (BCP = HA + TCP). For small defects,

the BMPs, it has proven effective determining the non-union healing [46].

. Recently, new techniques have become available to obviate to this

The biological chamber is a concept that represents the ideal site in which to brought out the bone regeneration processes. Is a natural bio-reactor within which are present all the elements at the base of the diamond concept. It is even, physically, the site of non-union or of bone loss specially prepared from the surgeon with the aim to create the best condition for the regener‐ ation. The chamber has to be aseptic, mechanically stable, and sealed in a selectively permeable way [25].

To use the chamber is necessary to remove completely the pathologic non-union tissue, removing all external bodies and meaning of synthesis. Is important to remove in a complete way all the necrotic tissue up to a bleeding bone resection that means vitality. The non-union tissue can be assimilated to a "meta-traumatic tumor" and as such, it must be removed entirely. In case of non-union or septic bone loss is important to do cultural withdrawal with the aim to identify the pathogen responsible of sepsis and perform targeted antibiotic therapy. Over the removal of the infected bone tissue is important to do a debridement and an accurate toilette of the soft tissues.

In septic cases is always preferable to do a two times treatment, then, once performed the removal of the pathologic tissue need to be implanted a cement spacer usually two antibiotics added (the choice of the active principle has to be done on the base of the antibiogram, when available) able to sterilize the site and create a reactive pseudo synovial membrane (described by Masquelet) extremely useful in the second reconstructive time [49].

In non-septic cases you can run a single surgical time reconstruction. Once created the biological chamber is then possible to insert within it polytherapy, or rather the simultaneous application of the three elements at the base of the diamond concept (growth factors, mesen‐ chymal stem cells, and scaffolds). The fourth element, that is mechanical stability, will be provided by ostheosynthesis meaning (angular stability plates).

Case 1 (**Figures 1**–**4**)

**Figure 1.** Clinical case 1—Man, 49 years, initial trauma following a motorcycle accident in which suffered exposed tibi‐ al pilon fracture, four ineffective treatments previously, comes to our attention (see X-rays and TC images) with a pic‐ ture of septic non-union with serious bone loss and varus deformity, NUSS: 56 points.

**Figure 2.** Intraoperative pictures that evidence: non-union site (a). Osteotomy with cruentation and removal of the pathologic tissue saving the joint surface came to healing after all previous treatments (b). The creation of the "biologi‐ cal chamber" (c). The implantation of antibiotic cement added with gentamicin and clindamycin (d).

**Figure 1.** Clinical case 1—Man, 49 years, initial trauma following a motorcycle accident in which suffered exposed tibi‐ al pilon fracture, four ineffective treatments previously, comes to our attention (see X-rays and TC images) with a pic‐

**Figure 2.** Intraoperative pictures that evidence: non-union site (a). Osteotomy with cruentation and removal of the pathologic tissue saving the joint surface came to healing after all previous treatments (b). The creation of the "biologi‐

cal chamber" (c). The implantation of antibiotic cement added with gentamicin and clindamycin (d).

ture of septic non-union with serious bone loss and varus deformity, NUSS: 56 points.

116 Advanced Techniques in Bone Regeneration

**Figure 3.** Radiographic post-op images that evidence the stabilization with external fixation, the positioning of the ce‐ ment spacer and the deformity correction.

**Figure 4.** X-rays post-op images after the second reconstructive surgery performed by grafting biotechnologies in poly‐ therapy and stabilization with double angular stability plate (a). CT control after 9 months (b).
