Purpose: Growth modulation with tension band plates (TBPs) and cannulated screws is the current mainstay of treatment for pediatric lower extremity angular deformities. Solid screws have been used as an alternative to cannulated screws to decrease the risk of screw failure, particularly in obese children. The downside of solid screws is the decrease in precision of placement. This study describes a surgical technique to insert solid TBP screws accurately.
Methods: TBP insertion starts with the same conventional steps by inserting the guidewires into the epiphysis and metaphysis, straddling the physis. After fluoroscopic confirmation of the position of the guidewires, the cannulated drill bit is used to broach the cortex to a depth of 5 mm in the bone. A standard 4.5-mm cannulated screw from the TBP set is used to tap the screw tract over the guidewires for approximately three-quarters of the planned screw length. After removing the guidewires, the solid screws are then inserted in each hole to follow the tapped tracts.
Results: This technique was used in five patients including four with Blount disease and one with bilateral genu varum.
Conclusion: It is recommended to use solid screws with TBPs in patients with a high body mass index to avoid screw fracture. Our technique describes using a cannulated screw as a tap to create a tract to ease accurate insertion of the solid screws, and prevent the solid screw from deviating outside the desired path.
Keywords: Bone screws; Growth modulation; Tension band plate.