Limb Lengthening - Procedure, Recovery, and Complications

Introduction

Limb lengthening is an orthopedic surgical procedure used to lengthen arms or legs. Limb lengthening is done in the case of limb length discrepancies, a condition in which one limb (leg or arm) is shorter than the other. Limb length discrepancies can affect one’s quality of life as length discrepancies in the legs can cause hip pain, knee pain, and abnormal gait. Likewise, discrepancies in the arm can cause shoulder pain and back pain. The differences in the length of limbs can be due to certain congenital or acquired conditions.

What Are the Causes of Limb Length Discrepancies?

The congenital conditions that can cause limb length discrepancies include:

• Congenital Short Femur - This condition is characterized by shortened femur or absence of the femur bone.

• Hemihypertrophy - It is when one side of the body grows larger than normal.

• Fibular Hemimelia - A condition in which the femur is missing or underdeveloped.

• Hemiatrophy - A condition in which one side of the body grows smaller than the other.

Acquired conditions include trauma to the bone, bone infections, or bone tumors.

Some medical conditions, like polio, cerebral palsy, etc., can also result in unequal limbs.

What Are the Considerations for Limb Lengthening?

The following things are to be considered in the limb lengthening procedure:

• If the limb shortening is less than two centimeters (cm), it is usually ignored.

• If shortening is between two to four cm, lengthening is possible.

• If shortening is more than four cm, lengthening is necessary to avoid complications such as pelvic obliquity(the pelvis is asymmetrical; one hip is at a higher position than the other).

• For differences in limbs more than five cm, epiphysiodesis (surgery performed on the growth plate) is used in growing bone, or shortening the longer leg is done.

• The cause for the discrepancy should be considered before the limb lengthening procedure.

• The height of the patient, the opinion of family members, and psychological aspects should also be considered.

• In the case of dwarfism, bilateral lengthening is done.

• Childhood and early adulthood are the ideal age groups for limb lengthening procedures.

• Limb lengthening can cause joint problems if joints on both ends of the bone to lengthened are unstable.

• If the tissues at the surgery site are scarred, then the surgical procedure possess a further risk of damage to these tissues.

What Is the Limb Lengthening Procedure and the Science Behind It?

The limb lengthening procedure can be divided into three stages:

1. Surgical Stage

In this stage, the orthopedic surgeon cuts the bone to be lengthened. This procedure of cutting the bone into segments is called an osteotomy. The osteotomy procedure creates two separate bone segments. Soft tissue procedures are done to preserve blood flow and to lengthen muscles or tendons. For example, Achilles tendon lengthening is done while doing tibial lengthening. An orthopedic lengthening device creates a gap between the bone segments. If the orthopedic lengthening device is inserted into the bone, it is called an internal device. On the other hand, if the orthopedic lengthening device is placed outside the body, it is called an external fixator. After surgery, about a week of rest is given to the limbs before the next stage starts.

2. Distraction Phase

This is a recovery stage. During this stage, the bone segments are separated or pulled apart with the help of an orthopedic lengthening device. The clinical team trains the patient or family member on how to lengthen the device in small required amounts each day. The bone segments are separated gradually by a process called distraction and this help in the formation of new bone in the gap between the segments. This new bone formed is called regenerated bone. This process of new bone formation by distraction is called distraction osteogenesis. Based on the radiologic evaluation of regenerated bone formation, the rate of distraction is increased or decreased by the surgeon. During this stage, physical therapy should be done two to five times a week.

3. Consolidation Phase

In the consolidation phase, the new bone formed between the segments gets consolidated, which means it hardens or calcifies. This phase takes about two to three months for the bone to solidify. Avoiding nicotine, a diet rich in proteins, and vitamin and mineral supplements can help in the healing process.

What Is the Recovery Time After the Limb Lengthening Procedure?

The recovery time after the procedure varies from patient to patient. Adults take more time to heal (almost double) as compared to children. Patients are advised to follow a nutritious diet and to take vitamin D3 supplements and calcium supplements for faster recovery. The exercises as suggested by the surgeon and physical therapist should be done. Physical therapy plays an important role in keeping the joints flexible and in improving muscle strength.

Which Are the Different Orthopedic Lengthening Devices?

Limb lengthening can be achieved by using internal orthopedic lengthening devices or an external fixator. The choice of the device is done by the surgeon considering the patient's opinion. The two types of devices are:

• External Fixators: These devices are placed outside the body, either surrounding the limbs or parallel to it. These are attached to the bone by pins and lengthened using a handheld tool.

• Internal Lengthening Rods: These rods are placed inside the bone and are lengthened with a magnetic device. Removing the rod is usually an outpatient procedure that does not need hospital admission.

What Are the Complications?

The outcome of the limb lengthening procedure largely depends on the expertise of the surgeon. The following are complications associated with the procedure:

• Pin-track infection is the most common complication associated with the use of external fixators. The material of the pin, wound care, surgical procedure, etc are factors contributing to pin track infection. Treatment involves oral antibiotics in mild cases and removal of pins in case of severe infection. Using hydroxyapatite-coated pins can reduce the risk of infection.

• Damage to muscles or nerves.

• Bone not reaching the desired length.

• Infection at the incision site.

• Joint stiffness.

Conclusion

Limb lengthening has a success rate of four out of ten. There are risks associated with the procedure, like infection, joint stiffness, etc. But, the procedure is beneficial in case of limb length discrepancies that affect one’s quality of life. The expertise of the surgeon also plays a role in the success of the procedure. So the decision for limb lengthening should be taken only under the guidance of an experienced surgeon.