EXTERNAL FIXATOR (Frame)
Bone lengthening over a nail is a procedure to lengthen bones that are shorter than normal due to injury, growth disturbance or a birth defect. The goal of regenerating bone length is to give the person equal limb lengths. This will help with cosmetic appearance and function.
How is new bone formed?
When a bone is broken, immature bone is formed at the region of the break. This is a precursor to new bone formation and is not as hard as mature bone, but rather is moldable or pliable. Eventually, this immature bone will be replaced with bone which is hard and can bear full weight. If this immature bone is “stretched out” slowly over time before it is replaced with new bone, the bone can be made longer with new bone filling in the gap. This is how limb lengthening is done.
To lengthen a bone, the bone is cut or divided in a certain place. When the bone is cut, the two segments created can be moved apart.
What is a frame or external fixator and how does it work?
External fixation devices have been developed to control this movement. This is a hardware scaffolding outside of the body, hence “external” fixation. These devices are made of strong metal and will keep the bones stable as they undergo lengthening. The bone to be lengthened may be too small for use of newer magnetic lengthening nails that are placed inside the canal or central aspect of the bone; therefore, external fixation must be used to accomplish this goal. External fixation is built on to the arm or leg like scaffolding along the side of a building. Metal rings or bars are attached to the bones with pins or wires. Special nuts or components will be turned each day on the external fixator to create the movement of the two bone segments. A prescription will be given that tells the patient how many turns need to be made each day. As the segments move away from each other, immature bone and then new bone is formed in between the region of distraction creating length.
External fixation devices have been developed to control this movement. This is a hardware scaffolding outside of the body, hence “external” fixation. These devices are made of strong metal and will keep the bones stable as they undergo lengthening. The bone to be lengthened may be too small for use of newer magnetic lengthening nails that are placed inside the canal or central aspect of the bone; therefore, external fixation must be used to accomplish this goal. External fixation is built on to the arm or leg like scaffolding along the side of a building. Metal rings or bars are attached to the bones with pins or wires. Special nuts or components will be turned each day on the external fixator to create the movement of the two bone segments. A prescription will be given that tells the patient how many turns need to be made each day. As the segments move away from each other, immature bone and then new bone is formed in between the region of distraction creating length.