170 likes | 1.31k Views
The Use of a Blocking Screw to Prevent Malalignment of Proximal Third Tibial Shaft Fractures During Intramedullary Nailing. By Adam Morse, D.O. Garden City Hospital Garden City, Michigan. Introduction. Fractures of the proximal 1/3 of the tibia are relatively rare (5-7%, Lang et al), however,
E N D
The Use of a Blocking Screw to Prevent Malalignment of Proximal Third Tibial Shaft Fractures During Intramedullary Nailing By Adam Morse, D.O. Garden City Hospital Garden City, Michigan
Introduction • Fractures of the proximal 1/3 of the tibia are relatively rare (5-7%, Lang et al), however, • Malalignment after IM nailing of these fractures has been reported at rates from 58% (Freedman et al) to 84% (Lang et al) • Most authors agree that there is a high learning curve to nailing these fractures
Introduction • Numerous Authors have recommended abandoning the IM nail for these fractures including lang et al, 1995 • Others have recommended the following modifications: • Nailing in a semiextended position through a total knee incision: Tornetta & Collins, 1996 • Combining anterior unicortical buttress plating with IM nailing: Mathews et al, 1997
Introduction • Reduction of the fracture to within 5 degrees of anatomic has the following theoretical advantages: • returns a more normal range of motion in all planes • increases the rate of union • decreased rate of cosmetic functional deformities • normalizes joint forces to prevent uneven wear and progression of degenerative changes
Operative Technique • Pt supine, Tourniquet at 350, knee flexed over a well padded triangle or large bump • 6 cm midline incision is made from the inferior pole of the patella to the tibial tubercle • The medial patellar retinaculum is sharply incised along the border of the tendon • An Anterocentral starting hole in made with an awl after verification of position on both AP and Lateral x-rays
Posteriorly Directed Nail Insertion Leads to Apex Anterior Angulation and Posterior Displacement
Medial Starting Point Leads to Valgus Angulation and Lateral Displacement
Operative Technique • The Nail is then passed with or without a guide wire, and with or without reaming, based on physician preference • The alignment is checked in AP and Lateral planes for angulation and displacement • If the alignment is unacceptable the nail is backed out and a blocking screw is placed prior to reinsertion of the nail • The nail is locked proximally and distally based on physician preference and stability
The Blocking Screw • Any screw placed in bone with with the intent of effectively narrowing canal diameter to prevent translation of the nail • It is a concept, not a specific technique, which does not require a specific screw • It can be placed in any bone in any plane which necessitates increased translational stability of the nail in a widened medullary canal
The Blocking Screw • It has been successfully utilized in the supracondylar femur fracture, the proximal tibia fracture, and the pilon fracture • In the proximal tibia it is most frequently placed from medial to lateral in the metaphyseal bone as close to the fracture site as good fixation can be achieved • It’s effects are most pronounced in fractures with significant posterior comminution