Limb Lengthening and Intramedullary Nails
Limb Lengthening and Intramedullary Nails have a very advantageous connection, in this article, we will try to explore the history of the intramedullary nailing technique and how this technique evolved to be used in Limb lengthening surgeries.
What is an Intramedullary Nail?
An Intramedullary nail (IM nail) or rod; also known as the Küntscher nail; is a metallic nail/rod which is surgically embedded into the medullary cavity of the bone. Over decades, these nails have been used to treat fractures of the long bones, in the body. The first medical practitioner to employ the use of IM nails, was Gerhard Küntscher, in 1939, during World War 2, for soldiers returning from war with femoral fractures. Before the invention and implementation of IM nails; treatment of fractures was generally carried out with plaster, which required extended periods of inactivity. The advantage of using IM nails was that soldiers were able to return to activity, much earlier, sometimes within a matter of weeks, since the intramedullary nail supported the weight and load of the bone.
History of Intramedullary Nails?
Nicholas Senn was the first medical practitioner who even thought and began experimentation with intramedullary fixation inside the bone cavity, in 1893. However, it was the Rush brothers who, in 1937, began to practically use thin long flexible steel wires to stabilize long bone fractures. This method was quickly adopted in Vienna as the Ender school of fracture fixation. It was Robert Danis, who began experimentation and manufacturing nails in 1938 and used these short intramedullary implants for various fractures. However, it was Küntscher, who refined the method and introduced three important parameters which lead to the success of intramedullary nail fixation for long bone fractures. There were that, firstly, the insertion of the nails away from the actual fracture site, secondly, using nails of such a caliber that allowed for the mechanical and motoric function of a fractured limb, and lastly, he placed his intramedullary implant, to the full length of the bones’ marrow canal. In 1939, Küntscher’s operated his first intramedullary nailing procedure in a human. Thus, due to these advances, by the beginning of 1970, another medical practitioner, Klemm invented implants based on conventional open section nails with holes for bone screws, for increased stability and strength. By the start of 1984, an interlocking nailing technique for femoral and tibial long bones fractures became an established and well-accepted procedure in North-America, and the rest of Europe as well.
Limb Lengthening and Correction: Intramedullary Nails Vs External Fixators
Limb lengthening or as it is medically known as “Distraction Osteogenesis”; was originally discovered and operated by the Ilizarov method; which had established itself as a successful and widely accepted surgical technique for leg lengthening, limb deformity correction, and the reconstruction of non-unions or broken bones and inherent bone defects, such as bow legs and limb discrepancy. The original Illzarov’s method established two primary stages for limb lengthening, namely, distraction (bone lengthening) and consolidation (bone regrowth and healing). Now, this method essentially employed the external fixator for both of these processes. This fact leads to certain disadvantages, with the use of external fixator; primarily that in an adult it could require up to two months of an external frame time for every cm gained in height with lengthening.
This prolonged time in an external fixator lead to certain disadvantages:
1. First, there is a greater chance of health-related complications including pin tract infection and decreased range of motion in the surrounding joints.
2. Second, the process can affect the patient psychologically, increasing frustration, and decreasing compliance.
3. Finally, when the frame is removed, there is a risk for fracture of the regenerated bone due to the lack of any internal stabilization.
a. O’Carrigan reported an 8% fracture rate after frame removal in a review of 650 patients with 986 lengthening segments.
b. Danziger reported re-fracture of the femur in 6 of 18 patients after frame removal.
c. Simpson and Kenwright reported a fracture rate of 9.4% in a series of 180 lengthening segments.
On the other hand, at that time, intramedullary nails were primarily used for fracture healing and stabilization; and several randomized controlled studies found that managing long bone fractures with intramedullary nail over external fixator, had clear advantages. The studies focused on post-surgical complications and concluded that the use of external fixator for long bones fractures, were riddled with infections, fracture healing difficulties (non-union, mal-union) and “other complications” (soft tissue damage, mechanical failure, and tibia malalignment). In comparison, the studies found that the use of intramedullary nails for the treatment of bone fractures leads to lower rates of infections and fracture healing complications such as non-union or mal-union.
Several clinical trials have compared fracture management with intramedullary nails and external fixators, and one of the key factors has been the patient’s presentation of fracture and the experience of the surgeon. However still, external fixators involve shorter operating times but are not well tolerated and carry a higher incidence of complications including non-union, delayed union, and re-fracture. There are clear advantages of intramedullary nailing, with shorter healing time, earlier load-bearing (albeit initially partial), and a lower rate of complications; although it has longer operating times.
Combination Methods (Intramedullary Nails plus an External Fixator)
The use of external fixator alone in Distraction osteogenesis often requires a long period of external fixation, thus carries an increased risk of pin-track sepsis, malalignment, stiffness of the joint, and late fracture of the regenerate bone. In a recent study, to calculate the rate of post-surgery complication, found that limb lengthening methods which employed the use of a combination of both an intramedullary nail for strength and stability and external fixator for distraction purposes allowed for early post-surgery rehabilitation. There is a lower rate of complications than where an external fixator is used on its own, without the intramedullary nail. The time of external fixation is shorter than in other methods of leg lengthening. However, the risk of infection was unchanged and similar to standalone external fixator methods.
Advantages of the combination method:
1. Early full weight-bearing capabilities
2. Reduction in time spent on the external fixator
3. Lower rate of post-surgery complications
LON Method (Lengthening Over Nail)
Limb lengthening with the Ilizarov technique is considered a safe and successful surgical procedure with well-established biological principles. However, bone healing or consolidation phase of lengthening can take as long as thrice or four times the time spent on bone distraction or lengthening. At the same time. Patients constantly demand the removal of the fixator after the distraction phase is over, but the fixator cannot be removed until the bones can become weight-bearing and well-formed. Early removal of the fixator can be troubled with risks of loss of length as well as bending and axial deviation of the bone.
LON method or Lengthening with a combination of an intramedullary nail requires the locking of the intramedullary nail at the increased length at the end of the distraction or lengthening phase and removal of the external fixator. The regeneration of the bone within the surgical gaps is protected by the intramedullary nail in the consolidation phase and external fixation duration can be reduced by 40-60%. This surgical technique was first performed by Bost and Larsen in 1956 and has been popularized and mainstreamed by Dr. Paley (USA).
There are several advantages of combining intramedullary nail and external fixator:
1. Intramedullary nailing with external fixation, add much-needed stability to the whole construct of the limb lengthening system; and thus, it counteracts any adverse effect that reaming may have on the regenerate formation
2. The next benefit of the addition of the intramedullary nailing is the prevention of axial deviation during the fixation period and also after removal of the fixator over the long term.
3. This combined method is most beneficial for reducing the duration of external fixation. Most patients are very happy with the early removal of the fixator and easily tolerate the discipline of crutches and partial weight-bearing and braces that is needed in the fixation period.
Lengthening over an intramedullary nail is a very useful procedure in reducing the duration of external fixation as well as reducing the chances of axial deviation in limb lengthening. Risks with Intramedullary nail systems with external fixators are similar to standalone external fixator systems such as HolyFix or Illizarov, such as post-surgery infection, which should be prevented by a meticulous patient and doctor control of the surgical sites.
Please visit the following links in order to learn more about limb lengthening with the LON method and its relative costs and included services.
LATN Method (Lengthening and Then Nailing)
Another famous method, established by Dr. Rozbruch; which employs both an intramedullary nailing with external fixator is lengthening and then nailing (LATN) technique; whereby an external fixator is used for gradual distraction or lengthening and then a reamed intramedullary nail inserted to support the bone during the consolidation or bone healing phase, allowing for early removal of the external fixator. During the first surgery, only the external fixators are attached. When lengthening is complete, a second operation is performed to insert the internal nails and remove the external fixators. Two operations are required. Just like with LON, with LATN we can shorten the external fixation period to nearly half that of conventional Ilizarov methods.
LATN provides several advantages over the classic external only methods of limb lengthening, including shorter times needed in external fixation, quicker bone healing, and protection against re-fracture.
The advantages of LATN in contrast to LON (Lengthening over Nail) are as follows:
1. Bone formation is the faster and precise correction of leg alignment is possible.
2. This is why patients with bone angular derivations and deformities are recommended to consider the LATN method; then those looking for limb lengthening for purely cosmetic reasons.
However, there are some potential weaknesses of LATN. After the lengthening period, a correction period has to be added. Hence, an external fixator needs to be maintained for an additional 2-4 weeks, compared to LON. Furthermore, additional external fixator pins are inserted, than those with LON method.
Now, medical practitioners, generally employ the LON method for general stature or height lengthening; it is simpler and less expensive than LATN. However, in some cases, LATN can be very useful, especially in treating many rare deformation diseases that are otherwise difficult to cure.
To be continued in Article: Limb Lengthening Intramedullary Nails around the World