and Mark T. Dahl2
Department of Orthopedic Surgery, University of California – Irvine, Orange, CA, USA
Limb Length and Deformity Correction Clinics, Gillette Children’s Specialty Healthcare and University of Minnesota, St. Paul / Minneapolis, MN, USA
KeywordsParkhillCodivillaPuttiAbbottBost and LarsenIlizarovDistraction osteogenesis
Hind limb walking has been a defining feature of humans and their ancestors for at least 2 million years. Bipedalism confers clear advantages: the ability to see prey and predators while standing in tall savannah grasses and deep streams, the capacity to reach higher fruit in trees, and the aptitude to carry food and tools with the forelimbs.
Numerous subtle, but critical, adaptations evolved to make walking upright more energy efficient. The inward-sloping human femurs, for instance, reduce side-to-side displacement of the body’s center of mass, saving calories during walking (chimpanzees can walk short distances on their hind limbs but waddle while doing so—a fatiguing gait pattern) (Fig. 1.1).
Inward-sloping human femora (left), by placing the knees closer to the midline, reduce side-to-side waddling, compared to the chimpanzee (right). Copyright 2016 Zeeca Publishing Co
Moreover, an orthograde posture allows for an anteriorly positioned foramen magnum—the hole at the base of the skull for the spinal cord—permitting larger cranial capacity for the brain (Fig. 1.2).
Human upright posture moves the spinal column forward, allowing greater brain development . Copyright 2016 Zeeca Publishing Co
Likewise, the slight posterior downslope of the knee’s tibial weight-bearing surface permits a 10° knee flexion angle at midstance, thereby reducing up-and-down displacement of the center of mass—another energy saver. (A person with a straight stiff knee walks with a bouncing gait, like a car on a rutted road.)
Such anatomical modifications allow us to walk so efficiently that our center of mass displaces no more than 1 inch in any direction as it spirals through space-time, while we transition from right to left—and then back again—during the normal gait cycle.
Bipedalism comes, however, with a price. Unlike a three-legged dog, happily chasing tennis balls in the park, the loss of a lower limb in a human makes walking impossible without an ambulatory aid of some kind. Equally important, dysfunction of one or both lower limbs causes limping, a tiring way to get from place to place.
Although joint pain is the predominant cause of altered gait, unequal limb length disturbs gait as well. Ordinarily, humans can mask up to 1 inch of limb length difference by a combination of pelvic tilt and spinal curvature. Any discrepancy beyond that becomes an obvious impediment to efficient movement. Moreover, the incidence of osteoarthritis of the knee increases if limb lengths are unequal .
Until the middle of the last century , a shoe lift, sometimes many inches high, proved the only safe way to equalize lower limb length. With the advent of the aseptic operating room, pioneering surgeons searched for ways to elongate a short limb—or shorten the longer one—without causing a life- or limb-threatening infection while doing so.
There exists a distinct difference between elongating limbs that were originally of normal length in an adult, but were shorted by trauma, and those limbs whose childhood growth was stunted by a birth defect or by a traumatic, infectious, or developmental process, inhibiting natural function of the growth cartilage. In the former situation, the limb’s soft tissues were of normal length before the injury, so elongation becomes a matter of restitutio ad integrum. With inhibited childhood growth, the bone and soft tissues were never of normal size, so the periosseous soft tissues resist elongation of the limb.
Considering the above thoughts, it is no surprise that the first attempts at limb lengthening were to overcome post-trauma shortening. Clayton Parkhill, a surgeon working in Denver, Colorado, at the turn of the nineteenth century, devised the first practical external fixator that could be used in a variety of clinical situations . Among the illustrations in his published report, Parkhill corrected a femoral malunion with side-to-side healing and substantial fragment overlap. In general, his results with such operations proved favorable (Fig. 1.3).
Clayton Parkhill, of Denver, shown with his Parkhill bone clamp being used to treat a femoral malunion (1895). Copyright 2016 Zeeca Publishing Co
Alessandro Codivilla, a prominent Italian surgeon, used strong traction to restore length to shortened limbs . Unfortunately, his patients remained hospitalized throughout the elongation process (Fig. 1.4).
Alessandro Codivilla, with his traction device for gaining limb length after osteotomy of the bone (1905). Copyright 2016 Zeeca Publishing Co
Vittorio Putti, a student of Codivilla, first used an external skeletal fixator to slowly elongate a bone after a step cut osteotomy, thereby allowing some overlap and side-to-side contact between fragments when the full length was achieved . The lengthening mechanism contained a spring within the elongating tube to maintain tension throughout the process, which no longer required continuous hospitalization. However, bone grafting was often necessary at the end of the elongation process (Fig. 1.5).
Vittorio Putti and his spring-containing external fixator for limb lengthening (1921). Copyright 2016 Zeeca Publishing Co
San Francisco became a center of limb lengthening for children when LeRoy Abbott created a more stable external fixator in 1939 than the one used by Putti a generation earlier . Abbott’s device used two transosseous pins in each fragment, thereby enhancing the stability of the bone-fixator construct (Fig. 1.6). His innovative mind inspired generations of San Francisco orthopedic surgery residents. For this reason, the orthopedic alumni association of the University of California, San Francisco, is, to this day, named “The LeRoy Abbott Society.”
LeRoy Abbott and his lengthening fixator (1939) containing two transosseous pins in each fragment. Copyright 2016 Zeeca Publishing Co
Bost and Larsen
Fredrick Bost and Loren Larsen, both working at the San Francisco Unit of the Shriners Children’s Hospital System, reported on their experience with a new external fixator for limb lengthening in 1956 . It incorporated features of a Thomas splint and transfixion pins to slowly distract an osteotomized bone (Fig. 1.7). In about half of their patients, newly formed bone filled the widening distraction zone, a harbinger of Ilizarov’s discoveries. However, the phenomenon was unpredictable, and half of their patients required bone grafting to fill the distraction gap.
Fredrick Bost (left) and Loren Larsen (right) of San Francisco, with their distraction system (top). In about half their cases, new bone formed in the distraction zone, as shown. Copyright 2016 NuVasive
G. A. Ilizarov
In 1951, Soviet surgeon G. A. Ilizarov (Fig. 1.8) unlocked a previously hidden capacity of bone to form new osseous tissue reliably in a widening distraction gap under the appropriate conditions of stability and elongation .
Gavriil Abramovich Ilizarov, 1921–1992. Copyright 2016 Zeeca Publishing Co
While serving as a physician at a veterans’ clinic in Kurgan, Siberia, USSR, Doctor Ilizarov cared for a patient who had sustained a traumatic below-knee amputation during the Second World War. As sometimes happens in such cases, a 90° flexion deformity of the knee evolved, making it impossible to fit the retired soldier with an artificial limb.
Moreover, the knee joint underwent spontaneous bony ankylosis, such that a solid mass of bone filled the entire region that had formerly been the man’s knee.
Ilizarov’s treatment plan started with an oblique cut through the bone mass, followed by application of a simple external fixation device, with one tensioned wire through the femur, and another through the tibial stump. These wires were secured to half rings, which, in turn, were connected by threaded distraction rods .
The patient was instructed to turn the threaded rods to a small extent each day, thereby separating the half rings, a maneuver that would gradually straighten the knee. Ilizarov had planned to fill in the resulting triangle-shaped bone defect with a bone graft once the distraction had been completed, eventually allowing proper fit of an artificial limb. The grafting operation, however, was delayed as Dr. Ilizarov went on a Crimean peninsula summer vacation.
To his surprise, upon returning, Ilizarov discovered that newly formed bone had filled the entire distraction gap, eliminating the need for a bone graft.