The application of Bonelike® Poro as a synthetic bone substitute for the management of critical-sized bone defects - A comparative approach to the autograft technique - A preliminary study

Abstract

The effective treatment of non-unions and critical-sized defects remains a challenge in the orthopedic field. From a tissue engineering perspective, this issue can be addressed through the application bioactive matrixes to support bone regeneration, such as Bonelike®, as opposed to the widespread autologous grafting technique. An improved formulation of Bonelike® Poro, was assessed as a synthetic bone substitute in an ovine model for critical-sized bone defects. Bone regeneration was assessed after 5 months of recovery through macro and microscopic analysis of the healing features of the defect sites. Both the application of natural bone graft or Bonelike® Poro resulted in bridging of the defects margins. Untreated defect remained as fibrous non-unions at the end of the study period. The characteristics of the newly formed bone and its integration with the host tissue were assessed through histomorphometric and histological analysis, which demonstrated Bonelike® Poro to result in improved healing of the defects. The group treated with synthetic biomaterial presented bone bridges of increased thickness and bone features that more closely resembled the native spongeous and cortical bone. The application of Bonelike® Poro enabled the regeneration of critical-sized lesions and performed comparably to the autograph technique, validating its octeoconductive and osteointegrative potential for clinical application as a therapeutic strategy in human and veterinary orthopedics.

Keywords: Bone regeneration; Bonelike®; Ceramic biomaterials; Critical bone defects; Ovine model.

Fig. 1

Sequence of the surgical technique and micro-computed tomography (μCT) imaging of the defect: a) ileum ala presenting gluteus medius muscle incision; b) total thickness circular bone defects with 17 mm diameter performed on the mid portion of the ileum; c) total thickness circular bone defects with 17 mm diameter at the mid portion of the ileum before treatment; d), e) and f) μCT imaging of the bone defect area.

Fig. 2

Image Processing Sequence of the defect area using ImageJ® software and threshold analysis tool. CT group: upper panel, AG group: middle panel, BL group: lower panel. Unmineralized voids: a, b, c; Bone: d, e, f; Unfilled area (connective tissue): g, h; Biomaterial: i; Total area: j, k, l.

Fig. 3

XRD diffractogram of BMP showing the presence of the 3 crystalline phases, HA, β-TCP and α-TCP.

Fig. 4

SEM images of BMP (Total magnification: A - 65×, B -10,000×).

Fig. 5

In vivo post-operative (left) and post-mortem ex vivo (right) representative X-Ray images for BLP, AG and CT groups. Defects in vivo highlighted in red.

Fig. 6

SEM images (left panel) and corresponding histological images with HE (right panel). A: CT group, B: AG group, C: BLP group.

Fig. 7

SEM images and EDS analysis of the bone samples. CT group: upper panel, AG group: middle panel, BLP group: lower panel.

Fig. 8

Amplified SEM images of the bone samples. A: AG group: image detail of the autograft/mature bone interface; B, C and D: BLP group: image detail of Bonelike® interface with newly formed bone.

Fig. 9

Histological image stained with H&E. Left panel corresponding to the full scan of the samples and the right panel to a 20× magnification of a specific field of the sample (identified by the insets): a) Score 0 (CT group), b) Score 0,5 (AG group), c) Score 4 (BLP group), d) Score 4,5 (AG group), and e) Score 5 (BLP group).

Fig. 10

Area fraction of unmineralized voids, bone, unfilled area (connective tissue) and biomaterial, and bone bridge thickness. Results presented as Mean ± SEM. Significance of the results indicated according to P values with one, two, three or four of the symbols (*) corresponding to 0.01 < P ≤ 0.05, 0.001 < P ≤ 0.01, 0.0001 < P ≤ 0.001 e P ≤ 0.0001, respectively.