Graft materials provide greater static strength to medial opening wedge high tibial osteotomy than when no graft is included

Abstract

Background The purpose of this study was to compare the stability of medial opening-wedge high tibial osteotomy (MOWHTO) with and without different graft materials. Good clinical and radiological outcomes have been demonstrated when either using or not using graft materials during MOWHTO. Variations in the biomechanical properties of different graft types, regarding the stability they provide a MOWHTO, have not been previously investigated. Methods A 10 mm biplanar MOWHTO was performed on 15 artificial sawbone tibiae, which were fixed using the Activmotion 2 plate. Five bones had OSferion60 wedges (synthetic group), five had allograft bone wedges (allograft group), and five had no wedges (control group) inserted into the osteotomy gap. Static compression was applied axially to each specimen until failure of the osteotomy. Ultimate load, horizontal and vertical displacements were measured and used to calculate construct stiffness and valgus malrotation of the tibial head. Results The synthetic group failed at 6.3 kN, followed by the allograft group (6 kN), and the control group (4.5 kN). The most valgus malrotation of the tibial head was observed in the allograft group (2.6°). The synthetic group showed the highest stiffness at the medial side of the tibial head (9.54 kN·mm − 1 ), but the lowest stiffness at the lateral side (1.59 kN·mm -1) . The allograft group showed high stiffness on the medial side of the tibial head (7.54 kN·mm − 1 ) as well as the highest stiffness on the lateral side (2.18 kN·mm − 1 ). Conclusions The use of graft materials in MOWHTO results in superior material properties compared to the use of no graft. The static strength of MOWHTO is highest when synthetic grafts are inserted into the osteotomy gap. Allograft wedges provide higher mechanical strength to a MOWHTO than when no graft used. In comparison to the synthetic grafts, allograft wedges result in the stiffness of the osteotomy being more similar at the medial and lateral cortices.

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

“… 2 , 30 In the presence of a lateral hinge fracture, the use of a structural allograft also provides superior construct stability and more consistent results after cyclic fatigue testing. 2 Consistent with the findings from these biomechanical studies, 1 , 2 , 30 several studies of MOWHTO with a structural allograft reported satisfactory results with regard to low rates of nonunion or implant failure, ranging between 0% and 4%. 9 , 17 , 18 , 23 , 25 , 27 However, in many of these series of MOWHTO with a structural allograft, a more conservative delayed weightbearing protocol was adopted.…”

“… 5 , 12 To avoid adverse outcomes after a lateral hinge fracture, several reinforcement strategies such as additional opposite screw fixation and bone graft augmentation have been validated to improve structural stability in several biomechanical studies and finite element analyses. 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts.…”

“… 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts. 2 However, to fill the osteotomy gap with a structural allograft only when a lateral hinge fracture is recognized intraoperatively might not be an effective strategy.…”

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

“… 2 , 30 In the presence of a lateral hinge fracture, the use of a structural allograft also provides superior construct stability and more consistent results after cyclic fatigue testing. 2 Consistent with the findings from these biomechanical studies, 1 , 2 , 30 several studies of MOWHTO with a structural allograft reported satisfactory results with regard to low rates of nonunion or implant failure, ranging between 0% and 4%. 9 , 17 , 18 , 23 , 25 , 27 However, in many of these series of MOWHTO with a structural allograft, a more conservative delayed weightbearing protocol was adopted.…”

“… 5 , 12 To avoid adverse outcomes after a lateral hinge fracture, several reinforcement strategies such as additional opposite screw fixation and bone graft augmentation have been validated to improve structural stability in several biomechanical studies and finite element analyses. 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts.…”

“… 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts. 2 However, to fill the osteotomy gap with a structural allograft only when a lateral hinge fracture is recognized intraoperatively might not be an effective strategy.…”

Use of Grafts on an Open Gap Is Advantageous for Preventing Correction Loss in 1-Week Staged Bilateral Open-Wedge High Tibial Osteotomies

“…Specifically, the use of allogenic bone grafts, where the relevant outcomes for bone union were not superior to not using grafts, is not strongly recommended in OWHTOs 9 . However, allogenic bone graft use contributes to initial stability of the osteotomy site in a biomechanical study; Belsey et al 5 reported that 10-mm biplane OWHTOs, performed on saw bone tibias, with allogenic bone graft failed at 6 kN of static compression load, while those without grafts failed at 4.5 kN, although a statistical analysis was not performed in this biomechanical study.…”

Bone Healing and Clinical Outcome Following Medial Opening‐wedge High Tibial Osteotomy Using Wedge‐Shaped Cancellous Allograft

“…First, the implantation of the wedge‐shaped cancellous allograft provided additional intrinsic stability to the osteotomy gap, which allowed patient to begin weight bearing as early as the second to third day after surgery. The advantages of the wedge allograft in terms of mechanical strength and stiffness had been proved in an in vitro mechanical test by Belsey et al 54 . Second, axial loading forces can be redistributed by this press‐in graft and therefore it can be used as a load‐sharing implant with the same structural properties as the recipient bone.…”

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

“… 2 , 30 In the presence of a lateral hinge fracture, the use of a structural allograft also provides superior construct stability and more consistent results after cyclic fatigue testing. 2 Consistent with the findings from these biomechanical studies, 1 , 2 , 30 several studies of MOWHTO with a structural allograft reported satisfactory results with regard to low rates of nonunion or implant failure, ranging between 0% and 4%. 9 , 17 , 18 , 23 , 25 , 27 However, in many of these series of MOWHTO with a structural allograft, a more conservative delayed weightbearing protocol was adopted.…”

“… 5 , 12 To avoid adverse outcomes after a lateral hinge fracture, several reinforcement strategies such as additional opposite screw fixation and bone graft augmentation have been validated to improve structural stability in several biomechanical studies and finite element analyses. 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts.…”

“… 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts. 2 However, to fill the osteotomy gap with a structural allograft only when a lateral hinge fracture is recognized intraoperatively might not be an effective strategy.…”

Use of Grafts on an Open Gap Is Advantageous for Preventing Correction Loss in 1-Week Staged Bilateral Open-Wedge High Tibial Osteotomies

“…Specifically, the use of allogenic bone grafts, where the relevant outcomes for bone union were not superior to not using grafts, is not strongly recommended in OWHTOs 9 . However, allogenic bone graft use contributes to initial stability of the osteotomy site in a biomechanical study; Belsey et al 5 reported that 10-mm biplane OWHTOs, performed on saw bone tibias, with allogenic bone graft failed at 6 kN of static compression load, while those without grafts failed at 4.5 kN, although a statistical analysis was not performed in this biomechanical study.…”

Bone Healing and Clinical Outcome Following Medial Opening‐wedge High Tibial Osteotomy Using Wedge‐Shaped Cancellous Allograft

“…First, the implantation of the wedge‐shaped cancellous allograft provided additional intrinsic stability to the osteotomy gap, which allowed patient to begin weight bearing as early as the second to third day after surgery. The advantages of the wedge allograft in terms of mechanical strength and stiffness had been proved in an in vitro mechanical test by Belsey et al 54 . Second, axial loading forces can be redistributed by this press‐in graft and therefore it can be used as a load‐sharing implant with the same structural properties as the recipient bone.…”

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

“… 2 , 30 In the presence of a lateral hinge fracture, the use of a structural allograft also provides superior construct stability and more consistent results after cyclic fatigue testing. 2 Consistent with the findings from these biomechanical studies, 1 , 2 , 30 several studies of MOWHTO with a structural allograft reported satisfactory results with regard to low rates of nonunion or implant failure, ranging between 0% and 4%. 9 , 17 , 18 , 23 , 25 , 27 However, in many of these series of MOWHTO with a structural allograft, a more conservative delayed weightbearing protocol was adopted.…”

“… 5 , 12 To avoid adverse outcomes after a lateral hinge fracture, several reinforcement strategies such as additional opposite screw fixation and bone graft augmentation have been validated to improve structural stability in several biomechanical studies and finite element analyses. 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts.…”

“… 1 , 2 , 30 The use of a structural allograft has shown biomechanical advantages such as higher stiffness, reduced stress of the lateral tibial cortex and the implant, decreased maximum displacement of the tibia, relative displacement of the medial gap, and decreased risk of implant failure and lateral hinge fractures. 1 , 30 In the presence of a lateral hinge fracture, patients with a structural allograft demonstrated the ability to withstand higher peak forces and had lower valgus malrotation, higher stiffness, and more consistent results from cyclic fatigue testing compared with those without bone grafts. 2 However, to fill the osteotomy gap with a structural allograft only when a lateral hinge fracture is recognized intraoperatively might not be an effective strategy.…”

Use of Grafts on an Open Gap Is Advantageous for Preventing Correction Loss in 1-Week Staged Bilateral Open-Wedge High Tibial Osteotomies

“…Specifically, the use of allogenic bone grafts, where the relevant outcomes for bone union were not superior to not using grafts, is not strongly recommended in OWHTOs 9 . However, allogenic bone graft use contributes to initial stability of the osteotomy site in a biomechanical study; Belsey et al 5 reported that 10-mm biplane OWHTOs, performed on saw bone tibias, with allogenic bone graft failed at 6 kN of static compression load, while those without grafts failed at 4.5 kN, although a statistical analysis was not performed in this biomechanical study.…”

Bone Healing and Clinical Outcome Following Medial Opening‐wedge High Tibial Osteotomy Using Wedge‐Shaped Cancellous Allograft

“…First, the implantation of the wedge‐shaped cancellous allograft provided additional intrinsic stability to the osteotomy gap, which allowed patient to begin weight bearing as early as the second to third day after surgery. The advantages of the wedge allograft in terms of mechanical strength and stiffness had been proved in an in vitro mechanical test by Belsey et al 54 . Second, axial loading forces can be redistributed by this press‐in graft and therefore it can be used as a load‐sharing implant with the same structural properties as the recipient bone.…”