The Use of Poller Screws (Blocking Screws) in Intramedullary Nailing

The Poller screw (blocking screw) technique was first described by Krettek’s research group. This technique is an important adjunct to intramedullary nailing and has been shown to be effective in assisting fracture reduction. It can help guide insertion of the intramedullary nail, control angular deformity, and improve the stability of the bone–implant construct.

To achieve correct reduction, the screw should be placed at the acute angle. By placing the screw at the widest part of the fracture, any degree of mismatch between the implant and the metaphysis can be maximally overcome. Therefore, the first screw should be placed in the optimal position whenever possible. When the intramedullary nail contacts the screw, the narrowing effect of the metaphyseal diameter deflects the nail in the intended direction so that the fracture end is reduced in the desired direction.

The author presents a case of closed reduction and intramedullary nailing to preliminarily illustrate the placement method for blocking screws (pins).

Preoperative X-ray

AP and lateral fluoroscopy after traction

Insertion of the guide pin

After proximal opening, insertion of the Golden Finger reduction device

Fluoroscopy showed posterior angulation of the fracture on the lateral view. The Golden Finger reduction device was withdrawn. Poller screws were inserted transversely and in the AP direction according to the acute-angle principle. The Golden Finger reduction device was reinserted, and the fracture was anatomically reduced.

A flexible reaming guidewire was inserted, sequential reaming was performed, and the intramedullary nail was inserted.

Distal and proximal locking screws were placed. Fluoroscopy showed good fracture reduction and good implant position. The Poller screws were removed.

Fluoroscopy showed nearly anatomical fracture reduction and good implant position.

Summary: The blocking screw (pin) must be inserted at the acute angle formed by the fracture line and the central axis. A simpler mnemonic: in whichever direction the fracture needs to be reduced, insert the blocking screw (pin) in that direction.