Height Lengthening for Constitutional Short Stature

Height Lengthening for stature in normally proportioned individuals with short stature but without dysplasia (dwarfism) requires a different strategy for lengthening than in patients with disproportion and dysplasia. Most patients with constitutional short stature (CSS) or low normal stature (LNS) require only modest increase in stature compared to the extreme amount of lengthening required by patients with dwarfism.

When assessing distribution of height in the population we consider the normal bell curve. We divide people by distribution around the mean (average), and normal height is considered plus/minus 3 standard deviations from the mean. Short stature below 3 standard deviations from the mean in individuals without a medical condition such as dwarfism, growth hormone deficiency etc., is considered constitutional short stature. The lower limit of so called normal stature for Caucasian men is 5’7” tall and for woman is 5’2”.

While patients with dwarfism are often treated in childhood, patients with constitutional short stature or low normal stature are not treated until they have completed growing. Patients with LNS and short stature also do not usually have deformities of the bones. To minimize the treatment time for lengthening we prefer the PRECICE lengthening method, as well as the lengthening and then nailing technique (LATN). This method minimizes the treatment time in the external fixator, limited to the time required to obtain the lengthening desired without having to wear the external device during the hardening or consolidation phase. This method also reduces the rehabilitation time, time to return to full weightbearing, work, school and recreational activities. A new fully implanted lengthening nail is available, called PRECICE. This approach would not require an external fixator at all and has shown to be very successful.

The usual goal of height lengthening for most patients with short stature is 2-3 inches. More than that amount cannot be achieved safely in one pair of bones during one lengthening. For more lengthening one needs to repeat the process in a second pair of bones, i.e. femurs or tibias.

The usual strategy for height lengthening is to lengthen both tibias including the fibula 2-3 inches using the LATN or PRECICE method. If a second lengthening is desired then both femurs are lengthened the same amount. Most patients do not choose to have the femurs done because of the added time commitment and the doubling of the expense. Furthermore, doing too much lengthening in the lower limbs in normally proportioned people leads to the obvious disproportion. Up to three inches of lengthening produces no obvious disproportion.

There is no preference for tibial lengthening over femoral lengthening. There are benefits for each (femur or tibia). First of all tibia lengthening makes ones legs look longer than femoral lengthening. The reason for this is that the level of the knees and feet are obvious but the level of the hips are not obvious. Depending on how we wear our belts, our hips seem to be higher or lower. When we see long lower legs we extrapolate that the rest of the person has a normal proportion which gives the impression that the individual is longer than they really are. Furthermore, wearing short skirts and dresses shows the lengths of the lower legs but not the thighs, therefore one gets more mileage in apparent increased height from tibial than from femoral lengthening.

The benefits of femur lengthening is that the amount of time it takes to lengthen and have the bones consolidate is much faster than that for tibias. During the lengthening process, your walking and standing is limited since there is a chance of hardware breakage with excessive weight bearing. With femur lengthening, since the bone consolidates much faster than the tibia, you will be able to be on your feet and get back to your normal activities much faster. For 6.5cm of lengthening, the amount of time required before full weight bearing in the femurs is about 3 months, compared to 4-4.5 months for the tibias.

Most patients are in the hospital between 2-4 days after the procedure. Physical therapy to stretch the ankles and knees begins in the hospital and continues after discharge as an outpatient. Patients need to have physical therapy for 1-2 hours every day during the 2-3 months of lengthening. The patients who do best work diligently at stretching their ankle and knee joints both at home and at therapy. Therapy can be carried out at any therapy center. The patients from out of town can do their therapy in their hometown. Remember you cannot do too much stretching. Ankle range of motion is the limiting factor for lengthening. As long as the patient can stretch the foot beyond 90 degrees, the lengthening can continue.

Patients are seen in follow up every two weeks during the lengthening phase. Even out of town patients need to be seen every two weeks. On these visits we perform nerve testing if needed, exam pin sites and obtain X-rays. Problems are identified and treated and medication prescriptions for pain or antibiotics are written. Occasionally adjustments to the external fixators are required in the office.

One can assume approximately one month of distraction for every inch (2.5 cm of lengthening). Lengthening does not begin until approximately one week after surgery. Therefore 2-3 inches of lengthening takes 2-3 months in the external fixator. Weight bearing is allowed within limits of pain.

At the end of the lengthening there is a second surgery to insert the intramedullary nails and the external fixators are removed for the LATN procedure. Since the rods only fix the tibias an additional screw is needed for each fibula to protect the fibula from shifting from the ankle. This screw can be removed 2 to 3 months later. After the external devices are removed the follow up is once a month for the first 2-3 months.
The new internal lengthening nail method with PRECICE does not require the application or removal of external frames.

Patients remain partial weightbearing until the X-rays show that the bone is healed enough to allow weightbearing. One or two intact cortices must be seen on X-ray. This usually takes 1-2 months after nail insertion. Most patients can begin weightbearing 4-6 weeks after removal. Physical therapy continues mostly to regain full ankle motion and foot push-off strength. This can take several more months. Therapy is only 3 days a week after removal but daily home exercises are recommended. Removal of rods is recommended in the future. This is not critical and can be done at anytime once the bones are fully healed. We generally perform this about one year after the lengthening is completed. Again, this is an outpatient or one night stay surgery.

While there are many potential complications of lengthening, other than mild pin infections they are uncommon. Ankle stiffness is a concern but a rare complication if intense therapy and home exercises are carried out and if the lengthening does not continue, if the foot position drops below 90 degrees (equinus contracture). Deep infection with tibia lengthening over nail is rare. It is resolved by removal of rod. Nerve injury is also rare.

All patients with lengthening for stature must undergo a psychological evaluation prior to the lengthening. This evaluation is needed before we will agree to offer the lengthening to a patient. Lengthening for stature is considered cosmetic and will usually not be reimbursed by insurance carriers. Therefore, all fees must be self paid in advance of the services contracted for.

We will be happy to prepare a cost estimate for the evaluation, surgery, anesthesia, X-ray, hospital and physical therapy costs after you have come in for your consultation. This estimate must be paid in advance prior to the surgery. Lengthening for stature may be reimbursable by insurance in some cases, especially if there is any evidence of a hormonal or hormone treated related basis for the short stature, or if there is associated deformity.

Finally the most important issue to consider is that lengthening for stature in any individual over 5 foot tall is primarily for cosmetic reasons and does not improve function. It does seem to improve body image in patients with what we call short person neurosis. Nevertheless, the issue of function is of greatest concern to us. This procedure can damage nerves, muscles and joints. If such damage were to occur it could become irreversible leading to long term problems such as arthritis, limitation of joint motion and pain.

Rare cases can even develop compartment syndrome (excess bleeding into the legs, which will require an emergent surgery), reflex sympathetic dystrophy which is a chronic pain condition and which may not be resolvable. Pulmonary embolism and deep vein thrombosis which are common with other forms of orthopedic surgery are rare with this surgery, but they can occur and could lead to sudden shortness of breath, chronic leg swelling and even death. While loss of life and limb have never occurred to us with this procedure, one must still weigh the risks of undergoing a major surgical procedure versus the benefits of increasing ones stature by 2-3 inches. Proceeding with the surgery is a very personal decision.