Correction

Correction of deformities is one important aspect of spine management. Usually this is achieved with surgical intervention. The art and science of orthopedics were actually borne out of correcting deformities particularly in children- thus the word orthopaedics coming from the word orthos- meaning straight and pais- referring to child.

Man has attempted every possible appliances that can provide mechanical advantage to correct spinal deformities. These are termed as spine implants or instrumentation. Patients would usually be surprised when they hear doctors discussing the use of hooks, wires and screws in their spine to correct their deformity problems. These appliances have been carefully designed to fit the anatomy of the spine. They are engineered to withstand the tremendous forces involved in the dynamics of body movement. They are constructed out of special materials that would produce the least reaction inside the human body. Nowadays, titanium spine implants are favorite choices owing to their inherent strength, inertness and compatibility with magnetic resonance imaging.

Keywords : Spine Implants

Spine Instrumentation

Distraction

Compression

Translation

Neutralization

Derotation

Hooks

Wires

Screws

Spinal instrumentation would correct the spine by either distracting or compressing spine segments. It can also translate segments into correction. Pedicle screws can derotate the spine because of the long lever arm it hold within the vertebra. Sometimes implants simple hold segments to neutralize its stability.

Hooks can be anchored to the lamina, facet and transverse process of the spine. It can provide a very good hold on both ends to provide distraction and even compressive forces to correct deformities. The classic Harrington Hook-Rod system employs this principle of distracting a curve into correction. Current generation of spine instrumentation systems still employ the hooks in their portfolios.

Wires are very simple materials. When inserted under the lamina of the spine it creates a powerful hold that can be used to translate a spine deformity into correction against strong rods. Another wire and rod construct is applied for neutralization. It has been a very popular device in the 80's referred to as the Luque instrumentation system. This procedure is still used as a salvage procedure when hooks and screws cannot be anchored for one reason or another.

Hooks and Rods System

Wires and Rods System

Screw and rod systems are the mainstay of most spine instrumentation system nowadays. It provides excellent correction of deformities when used properly. It can provide both distraction, compression and translation forces. It can also provide derotation forces to correct two plane deformities of the spine. The other side neutralizes the construct. Screws provide superior anchorage in the spine compared to hooks and wires.

Pedicle Screws and Rods

Pedicle screw and rod systems are very powerful and versatile instrumentations. It can translate curves into correction. Coupled with derotation forces we can correct scoliotic curves. Once neutralized with a similar contralateral construct we can make finer corrections by graduated compression and distraction forces. This combination of forces help in correcting complex curves of the spine.