If a patient has different limb lengths (limb-length discrepancy) because of an injury, a malunited fracture, or a congenital deformity, limb lengthening can be performed.
Limb-length discrepancy leads to an inclination of the pelvis, asymmetry of the spine, and unbalanced loading at the connecting joints of the pelvis to the spine. On the longer limb, the hip is less covered, which can lead to early arthritis. The limb can develop varus (bowleg) malalignment. These changes are more problematic the bigger the limb-length discrepancy is. Therefore, correction of limb-length discrepancy of more than 2 cm is usually recommended.
Limb lengthening can be performed using an intramedullary lengthening nail, such as the Precice nail (NuVasive, Inc., San Diego, California, USA). In certain complex cases, a six-axis external fixation frame, such as the Taylor spatial frame (Smith & Nephew, Memphis, Tennessee, USA) is required.
For intramedullary limb lengthening, a lengthening nail is implanted into the femur (thigh bone) or tibia (shin bone). The bone is osteotomized (cut) during surgery. Using an external remote control, the two parts of the lengthening nail can be distracted slowly and gradually, usually at a speed of 0.75 to 1 mm per day. In the distraction gap, new bone forms (callus distraction). After distraction, the new bone becomes hard and remodels until it is stable.
Simultaneous realignment and deformity correction are possible with the lengthening nail, using specific advanced techniques such as fixator-assisted nailing.
In addition to lengthening of the femur (thigh bone), the Precice nail can be used for lengthening of the tibia (shin bone).
Some complex or severe deformities cannot be corrected acutely with plates and nails, especially if doing so would mean danger to the skin, nerves, or blood vessels. The same is true for bones with active infection. In those cases, correction can be achieved using external fixation.
I have 20 years’ experience with Ilizarov surgery and modern computer-guided six-axis external fixation frames, such as the Taylor spatial frame (Smith & Nephew, Memphis, Tennessee, USA). This frame allows simultaneous gradual correction of bone shortening, rotation, and angulation in all planes.
The bone is cut minimally invasively through a 10- to 15-mm skin incision by creating multiple drill holes and connecting them with a small chisel. Approximately 1 week after surgery, the distraction of the newly forming bone and the correction of the deformity are begun. The distraction amount is usually up to 1 mm per day, depending on patient age, area of correction, and bone quality.
In all cases of limb lengthening, physical therapy plays a vital role. Physical therapy and stretching exercises must be performed daily to allow the muscles and tendons to grow the same way the bone does. Additionally, the range of motion of the joints must be preserved throughout the lengthening process.
Mobilization is started on the first or second day after surgery. Partial weight-bearing is almost always possible with the use of crutches. Approximately 2 weeks after surgery, showering with an external fixation frame without the need to cover it is possible. At the end of lengthening, as soon as some bone can be seen in the distraction gap on x-rays, full weight-bearing can commence.