Can Custom Bone Pegs Facilitate Effective Treatment Of Nonunions?
Nonunions can be difficult to address with any patient. Accordingly, the surgeon may benefit from any additional modalities that can prevent a recurrent nonunion after a revision. When evaluating a nonunion for surgical revision, one should critically evaluate the primary fixation. If a fixation technique has failed with the use of screws and both sides of the failed fusion have been penetrated, bone pegs can be a consideration for a secondary form of fixation.
The revised fusion will need primary fixation. My personal choice is to place the new fixation in a different manner than the one that had originally failed. When the surgeon removes the original screw fixation, there is a deficit. However, surgeons can use that deficit to their advantage as a lattice for bone growth. By placing a corticocancellous graft peg across the deficit site, the surgeon can achieve a secondary form of fixation with the benefits of rigidity and incorporation that corticocancellous grafts possess. The combination of pegs in conjunction with primary standard fixation will obviously increase stability. The increase of stability can only assist the surgeon in completing the goal of fusion.
The use of corticocancellous bone pegs has shown fusion rates of 90 percent in the hand.1 Commercial pegs may not be available and without a strong cortical wall, they could fail in the application process. The fabrication of a custom graft from a tricortical bone graft intraoperatively can actually be quite easy and completed in an efficient manner.
A Step-By-Step Guide To Surgical Technique
Presurgical planning should focus around fixation placement outside of the hardware deficits without compromising overall stability. Examples would be using a plate or staples instead of screws or placing the screws in a different manner. I also review the first surgical record to determine the length of the hardware that needs to be removed. This will optimize graft selection. Having an autograft harvested is ideal but rarely a reality. Therefore, I prescreen a few choices of allogenic tricortical iliac crest at the facility on the day of surgery.
The final look of the peg should be similar to a wedge nail with slight widening from the tip to the head. The cortical portion of the peg will have an “L” shape with cancellous bone filling in the “L” from tip to head. The short leg of the “L” will become the head of the peg. This shape gives rigidity to the peg.
In graft selection, I first look for an angle more than 90 degrees between the converging portions of the cortical wall. The rationale is if you have an angle at 90 degrees or more, you will have less fatiguing at the cortical convergence of the “L” while tamping the peg. Then I look for a straight, long arm portion of the graft. This will be the rigid portion of the peg. At this point, I roughly verify that the overall length will be as long as the fixation I am removing.