Platelet-rich plasma enhances rib fracture strength and callus formation in vivo

Abstract

Background: Rib fractures are a common traumatic injury affecting more than 350,000 patients a year. Early stabilization has shown to be effective in reducing pulmonary complications. Platelet-rich plasma (PRP) is a growth factor-rich blood product known to improve soft tissue and bone healing. We hypothesized that the addition of PRP to a rib fracture site would accelerate callus formation and improve callus strength.

Methods: Platelet-rich plasma was isolated from pooled Lewis rat blood and quantified. Thirty-two Lewis rats underwent fracture of the sixth rib and were treated with 100 μL PRP (1 × 10 6 platelets/μL) or saline. At 2 weeks, ribs were harvested and underwent a 3-point bend, x-ray, and microcomputed tomography, and callus sections were stained with 4',6-diamidino-2-phenylindole and Alcian blue and picrosirius red. At 6 weeks, ribs were harvested and underwent a 3-point bend test, x-ray, microcomputed tomography, and Alcian blue and picrosirius red staining.

Results: At 2 weeks, PRP increased callus diameter (9.3 mm vs. 4.3 mm, p = 0.0002), callus index (4.5 vs. 2.1, p = 0.0002), bone volume/total volume (0.0551 vs. 0.0361, p = 0.0024), cellularization (2,364 vs. 1,196, p < 0.0001), and cartilage (12.12% vs. 3.11%, p = 0.0001) and collagen (6.64% vs. 4.85%, p = 0.0087) content compared with controls. At 6 weeks, PRP increased fracture callus diameter (5.0 mm vs. 4.0 mm, 0.0466), callus index (2.5 vs. 2.0, p = 0.0466), BV/TV (0.0415 vs. 0.0308, p = 0.0358), and higher cartilage (8.21% vs. 3.26%, p < 0.0001) and collagen (37.61% vs. 28.00%, p = 0.0022) content compared with controls. At 6 weeks, PRP samples trended toward improved mechanical characteristics; however, these results did not reach significance ( p > 0.05).

Conclusion: Rib fractures are a common injury, and accelerated stabilization could improve clinical outcomes. Platelet-rich plasma significantly increased callus size, calcium deposition, and cartilage and collagen content at 2 and 6 weeks and trended toward improved strength and toughness on mechanical analysis at 6 weeks compared with controls, although this did not reach significance. These findings suggest that PRP may be a useful adjunct to accelerate and improve fracture healing in high-risk patients.

Keywords: Platelet-rich plasma; fracture repair; rats; rib fractures.

Figure 1.

At 6 weeks, PRP-treated rib fractures demonstrated increased callus diameter and callus index on radiographs compared with controls.

Figure 2.

At 6 weeks, PRP-treated rib fracture demonstrated increased mineralized bone volume on micro-CT compared with control ribs.

Figure 3.

At 6 weeks, PRP-treated rib fracture demonstrated increased cartilage and collagen deposition suggestive of increased endochondral ossification.

Figure 4.

At late time points, PRP-treated ribs trended toward increased toughness and strength, although this did not reach significance.