PMC7429766_01
First procedure. Radiographs of the left femur showing the cement spacer (a), the graft aspect at five months after the first grafting (b), and the graft collapse following nail dynamization (c).
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The first procedure (P1) was initiated at another institution with implantation of a cement spacer around the elongation nail (Figure 1(a)). After five months, X-rays seemed to show a satisfying graft integration except at the distal edge (Figure 1(b)). X-rays revealed a major collapse of the graft (Figure 1(c)).
Second procedure. Radiographs showing the second cement spacer (a), the bone graft aspect at six months after the second grafting (b), and the subsequent elongation nail breakage that occurred four months later (c).
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The first step of the second procedure (P2) consisted of complete removal of the soft and avascularized graft, restoration of femur length, repetition of distal nail locking, and implantation of a new cement spacer (Palacos R+G; Heraeus, Hanau, Germany) into the defect (Figures 2(a) and 2(b)). However, the patient continued to complain about pain until the breakage of the elongation nail occurred at 10 months after the second grafting (Figure 2(c)).
Third procedure. Radiograph showing a fracture of the integrated graft (arrow) and a partial cement spacer (star) into the residual lateral bone defect (a). X-rays (b) and CT-scan (c) demonstrating complete bone union at the last follow-up.
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The broken nail was replaced by a monobloc conventional nail (T2 femoral nailing system, Stryker, Kalamazoo, MI, USA), and then, a third cement spacer (Palacos R+G; Heraeus, Hanau, Germany) was prepared to fill in the lateral defect and wrap the bone extremities (Figure 3(a)). One year after the last procedure and four years following the first spacer implantation, X-rays and computerized tomography (CT) scan demonstrated a complete circumferential bone union with 1.5 cm shortening (Figures 3(b) and 3(c)).
Histological sections of induced membranes from P1 (a), P2 (b), and P3 (c). After 4% paraformaldehyde fixation, membrane fragments were embedded in paraffin and then sections were cut and processed for routine hematoxylin-eosin-saffron staining. Magnification 20x. Scale bar = 100 mum. The black star indicates the poly-methyl-methacrylate location before its removal. Fibroblast density is shown in (d) (mean number of fibroblasts per mm2 +- standard error of the mean from 3 different slides for each considered membrane). Plastic-adherent mesenchymal stromal cells were isolated according to the explant culture method (e); P2 membrane) and then characterized by flow cytometry according to their phenotypic profile: CD90+, CD73+, CD105+, and CD45- (f).
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P1 membrane histology and cytometry were found. P2 and P3 membranes displayed typical IM morphologies as they were organized in two layers (Figure 4). Conversely, the superficial layer in the P1 membrane was strikingly different since fibroblast density was only 820 +- 94 cells per mm2 (Figure 4(d)). Furthermore, as assessed by cell culture explant and further flow cytometry analysis (Figures 4(e) and 4(f)), P2 and P3 membranes contained numerous mesenchymal stromal cells (MSCs, CD45-/CD90+/CD73+/CD105+ phenotype) while P1 membrane was completely deprived of these cells.