Before the advent of distraction osteogenesis, the most common way of dealing with a modest lower extremity length discrepancy in a growing child was to retard or stop the growth of the opposite limb. Using growth charts to predict the difference in limb length at skeletal maturity, a surgeon could span a still-growing epiphyseal plate with thick bone staples, thereby slowing its growth. The staples could either be left in place until the growth plate closed completely or, if some additional growth was needed on the normal side, the staples could be removed before maturity, anticipating further growth. The results, however, are not always predictably successful.

When growth charts indicate that complete growth arrest is the best way to equalize limb length, permanent closure of the epiphyseal plate is easily accomplished by drilling out its cartilaginous center. This allows a bone bridge to form across the plate, ending its growth.

These two methods of epiphysiodesis (surgically stopping growth) are relatively simple outpatient procedures, a feature that makes them appealing to surgeons and parents alike. Sadly, the still-growing patient, a minor, has no legal status in the decision-making process, although it is the youngster that bears the lifelong consequences of the decision.

Once a child transitions into adulthood, the potential for stopping growth no longer exists, so the only option for equalizing limb length without lengthening the stunted limb is to shorten the normal one. Years ago, the standard shortening procedure involved open surgical removal of a predetermined length of bone, acutely closing the resultant defect and stabilizing the involved bone with a plate and screws.

More recently, techniques have evolved to perform the entire shortening operation with intramedullary instruments [1]. First, the surgeon reams out the medullary canal and inserts a saw that cuts the cortex transversely from the inside. Two such bone cuts, separated by the requisite distance, create a floating bone segment equal to the length of the planned shortening. Next, the surgeon uses a back-cutting chisel, shaped like a hook, to split the floating segment in half longitudinally. The surgeon uses instruments to maneuver the two half-cortices outward—into the surrounding soft tissues—and collapses the bone to its final length. Placement of a standard (locking) intramedullary nail completes the surgery.

The x-ray image following such an operation is odd-looking, indeed: two half-bone segments—floating forever in the soft tissues—surround the shortened bone.

Shortening any normal bone in an adult also shortens the surrounding soft tissues. Although shortened skin may shrink somewhat, shortened muscles no longer function optimally, weakening them. While 2.5 cm (1 in.) of muscle shortening is reasonably well tolerated, a 5.0-cm (2-in.) decrease in muscle length weakens it. Nevertheless, in the days before intramedullary lengthening nails, some residual weakness seemed preferable to an unpleasant external fixation experience on the stunted limb .

Now, however, since an operation to elongate the short limb with an intramedullary lengthening nail offers a similar perioperative patient experience to shortening a normal limb with intramedullary techniques, we anticipate the eventual relegation of the intramedullary saw and back-cutting chisel to the museum of historic orthopedic devices.

From a philosophical perspective, many of us in the limb lengthening community are loath to operate on a normal limb to equalize it to an abnormal one. We see it this way: Would a farmer with a healthy chicken and a sick chicken kill the healthy chicken to make soup for the sick chicken? We doubt it .

In the past, before Ilizarov developed a reliable method of overcoming substantial limb length inequalities, certain conditions—especially those manifesting at birth or developing shortly thereafter—were best managed with amputation and prosthetic fitting, often starting in early childhood. Clearly, a well-functioning artificial limb is superior to a shoe lift that measures 12.5 cm (5 in.) or more. The greater the discrepancy with the opposite side, the more desirable the prosthesic option becomes.

Ilizarov and his co-workers have developed remarkable limb lengthening strategies utilizing his circular frame’s adaptability to overcome many birth defects and early developmental maladies previously considered incurable. Proximal femoral focal deficiency, fibular hemimelia, tibial agenesis, and related disorders can now be successfully treated. Unfortunately, the therapeutic approach proves quite an ordeal for the patient, often requiring several separate frame applications during the growing years.

With the introduction of a reliable intramedullary lengthening nail, surgeons can now offer patients and their families hope that serious limb deficiencies can be treated without the inconvenience of external fixators and the concomitant risk of potentially long-lasting—even permanent—pin or wire site infections.

In some congenital limb deformities, the limb must first be shortened to reconstruct an abnormal joint. While this seems paradoxical, relieving tight soft tissues constitutes a requisite first step for bone repositioning osteotomies. Paley, of Miami, Florida, is a pioneering developer and advocate of this approach .

The availability of fully implantable lengthening devices means that, with sufficient ingenuity and long-term planning, surgeons will increasingly abandon external fixators and use intramedullary lengthening methods to compliment joint reconstruction operations, offering hope for previously untreatable conditions.

The North America’s limb lengthening surgeons meet annually to share new techniques devised to deal with the aforementioned conditions—and others as well. The excitement generated by intramedullary lengthening nails is unprecedented among these practitioners. Any American or Canadian surgeon planning to become involved with the exciting developments in limb lengthening and deformity correction should join the Limb Lengthening and Reconstruction Society-North America (LLRS-NA) . Comparable organizations exist in most countries and regions of the world.

Surgeons are anxious to apply new diagnostic tools to their clinical armamentarium if the measures improve patient outcomes. Innovative practitioners who develop such concepts are usually the first to introduce them to the healthcare community. Often, developer enthusiasm blinds innovators to the limitations of their brainchild. Thus, the medical literature is replete with examples of therapies that first appear with great fanfare, but don’t pan out over time. Rarely does the innovator hearken the demise of his or her own creation. Instead, it is other practitioners who do the deed.

Realistic assessment of techniques and devices to treat limb length deficiencies and deformities has proven difficult because of the wide range of pathological conditions that cause shortening and angulation. Therefore, comparison series whereby surgeons assess the merits of one device against another are very sensitive to complexity factors. Obviously, the surgeon with the most challenging and difficult deformities will likely have poorer outcomes than those who treat simpler conditions. Likewise, age and comorbidity factors also weigh heavily on outcomes, making comparisons exceedingly difficult.

To overcome these difficulties, LLRS-NA formed an ad hoc committee to solve the complexity problem. They created a complexity score that considers the number of planes of deformity; the amount of lengthening required; the clinical risk factors; the character of soft tissue defects; the greatest angular deformity to be corrected; the quality of the bone, e.g., osteoporotic and infected; and adjacent joint stability. The values for each of these seven domains are added together to yield a final complexity score, which ranges from 0 (least complex) to 28 (high complexity). The authors of the study, led by James McCarthy [2], are given the acronym LLRS-AIM, which stands for location, length, risk, soft tissues, angulation, infection, and motion. It is reproduced on the following page .