The Synthes Locking Compression Plate (LCP) System

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The Synthes Locking Compression Plate (LCP) System

Jessica A. Dahlberg and Kenneth A. Bruecker

The Synthes Locking Compression Plate (LCP) with its patented combination plate holes (combi‐holes) that accommodate conventional or locking screws was released in 2001 [1, Chapter 2]. Cortical or cancellous screws can be inserted in the dynamic compression unit (DCU) of the combi‐hole to provide axial compression. The other half of the combi‐hole is threaded and conical to accept a locking screw, allowing for fixed‐angle stability. As such, an LCP can be applied in two manners: as a compression plate or as a bridging “internal fixator” plate.

The strength of the locking fixation depends less on the integrity of the bone than on fixations using conventional compression plates. Locking plates allow rigid fixation of comminuted fractures using biological fixation and are ideal for fractures in weak bone. Furthermore, locking plates are the ultimate implant for minimally invasive plate osteosynthesis (MIPO).

The locking drill guide threads into the threaded portion of the combi‐hole in the plate in a fixed direction (uniaxial) for an angle‐stable construct (Figure 12.1). The threads of the locking screw are smaller than cortical screws, as they do not have to create compression between the bone and the plate. Locking screws also have a larger core diameter than conventional screws, allowing them to be stronger in bending and shear forces. The thread leads on the shaft and the head of the locking screw are 1 mm. The pitch on the threads in the head is 0.5 mm, or two threads per 1 mm of space, also known as a 2‐start thread. In a 2‐start thread, there are two sets of threads 180° apart. During screw insertion, the shaft and head spin at the same rate but the threads in the head travel twice the distance. If the screwhead threads come in contact with the plate threads and become 90° out of phase, a height/distance of 0.25 mm is created. The plate/screw/bone will adjust to allow the screwhead to properly thread into the plate without stripping the threads into the bone. The leading screwhead thread will tend to compress the plate against the bone until the threads come into phase. When the threads mate together, the plate will release some of the built‐up compression. Per the manufacturer, the Synthes stardrive screwhead design is 65% stronger in insertional torque than conventional hexagonal screwhead design (Synthes publication #036.001.395). Locking screws offer less risk of screw loosening than do conventional screws.

Diagram displaying a synthes locking compression plate with exchange arrows on the screw and leftward and rightward arrows on the right side of the plate.

Figure 12.1 Synthes locking compression plate.

(Source: Courtesy of AO foundation.)

12.1 Other Locking Compression Plate Manufacturers

Since its debut several years ago, many manufacturers have utilized the Synthes plate and screw design. However, most did not duplicate the 2‐start thread design. In 2004, New Generation Devices introduced a similar locking plate design with combination holes with 2‐start thread screwheads (Figure 12.2). The screw holes and heads are not conical, but the screwhead has a collar that prevents overinsertion (Figure 12.2).

Image described by caption and surrounding text.

Figure 12.2 New Generation Devices locking plate.

(Source: Courtesy of New Generation Devices.)

12.2 Applications of Implants

If using both locking and nonlocking screws in a plate, the surgeon has options depending on need.

Jun 13, 2021 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on The Synthes Locking Compression Plate (LCP) System

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