Axial Micromotion Locking Plate Construct Can Promote Faster and Stronger Bone Healing in an Ovine Osteotomy Model.

Zhihua Han,Jianhong Wu,Guoying Deng,Chun Bi,Jiandong Wang,Qiugen Wang

doi:10.3389/fbioe.2020.593448

Zhihua Han, Jianhong Wu + Show 4 more

Open Access

https://doi.org/10.3389/fbioe.2020.593448

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Abstract

Fixing bone fractures with controlled axial interfragmentary micromotion improves bone healing; however, the optimal type of implant construct for this purpose is still lacking. The present study describes a novel axial micromotion locking plate (AMLP) construct that allows axial interfragmentary micromotion of 0.3 or 0.6 mm. We investigated whether the AMLP constructs enhance bone healing compared to an ordinary locking plate (LP) using an ovine osteotomy model. The stiffness of the constructs was tested under axial loading. We created a 3-mm osteotomy in the left hind leg tibia of sheep that was then stabilized with a 0.3- or 0.6-mm AMLP or LP construct (n = 6/group). Bone healing was monitored weekly by X-ray radiography starting from week 3 after surgery. At week 9, the specimens were collected and evaluated by computed tomography and torsional testing. We found that the AMLPs had a lower stiffness than the LP; in particular, the stiffness of the 0.6-mm AMLP construct was 86 and 41% lower than that of the LP construct for axial loads <200 and >200 N, respectively. In the in vivo experiments, tibial osteotomies treated with the 0.6-mm AMLP construct showed the earliest maximum callus formation (week 5) and the highest volume of bone callus (9.395 ± 1.561 cm3 at week 9). Specimens from this group also withstood a 27% greater torque until failure than those from the LP group (P = 0.0386), with 53% more energy required to induce failure (P = 0.0474). These results demonstrate that AMLP constructs promote faster and stronger bone healing than an overly rigid LP construct. Moreover, better bone healing was achieved with an axial micromotion of 0.6 mm as compared to 0.3 mm.

Highlights

Stable fixation, preservation of the periosteal blood supply, and early functional rehabilitation are the main goals of bone fracture repair
We demonstrated that an locking plate (LP) with controlled axial micromotion promotes faster and stronger bone healing in an ovine osteotomy model, compared with ordinary LP, with better bone healing with interfragmentary axial motion at 0.6 mm than at 0.3 mm
These results are in line with previous work demonstrating that LP constructs with reduced stiffness achieved better outcomes for bone healing (Gardner et al, 2010; Bottlang et al, 2016; Mitchell, 2016)

Summary

Introduction

Preservation of the periosteal blood supply, and early functional rehabilitation are the main goals of bone fracture repair. Incorrect working length, plate length, and screw placement can cause overly rigid fixation, which can delay natural bone healing by suppressing callus formation at the near cortex, preventing union, or promoting nonunion, potentially leading to construct failure (Foux et al, 1997; Vallier et al, 2006; Henderson et al, 2008, 2010; Lujan et al, 2010; Bogunovic et al, 2013; Bottlang et al, 2016; Elkins et al, 2016; Hofmann-Fliri et al, 2020). Controlled axial dynamization was shown to accelerate bone healing (Kenwright et al, 1986; Gardner et al, 2010; Bottlang et al, 2016)

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