Limb (Leg) Lengthening Methods, Nails & Process – How Does it Work?
Written by Joshua Leaf | Updated on September 26, 2021
Limb (leg) lengthening surgery is the process of gradually lengthening bones and soft tissues with the assistance of an external and or internal fixator. Some must undergo this surgery due to accidents or deformities, while others just want to gain a few inches in height. No matter the reason, this article will summarize the four-step process and review the seven most common leg lengthening nails and methods.
What is Limb Lengthening?
Limb (leg) lengthening surgery, height surgery, or stature lengthening all refer to the gradual process of elongating bones and soft tissues (including skin, muscles, ligaments, and nerves). This procedure is frequently performed to lengthen an individual’s legs or arms. When performed on the legs, it is very often referred to as ‘Leg Lengthening.’
At the core of limb lengthening is the general biological response to tension stress . When damage to soft tissue and bone occurs, the body naturally undergoes a natural regeneration process to fix the injured area. Limb lengthening involves an intentional fracture of the bone to promote natural healing and elongation.
Process or Phases of Leg Lengthening Surgery
For a more detailed exploration of the limb lengthening process, each of the four phases of the procedure will be explored with more detail. The four phases are:
Leg Lengthening: Surgery Phase
During the osteotomy, the bone to be lengthened is surgically cut to into two segments. The doctor may proactively make incisions in soft tissue such as the IT band (iliotibial band) to prepare for distraction of lengthening of the bone.
Limb Lengthening Fixators
The second key component of the surgery is the application of a fixator (an orthopedic lengthening device). Fixators can be categorized as external fixators and internal fixators.
For external fixators, wires and pins are required to attach the device to the bone. Essentially, the fixator acts like a scaffold, a temporary structure designed to support the separated bone segments. Limb lengthening occurs mechanically, as the segments of bones are physically pulled apart by the system.
Internal fixators are also commonly used in limb lengthening. They may also be referred to as intramedullary nails, intramedullary rods, or telescopic nails. This is because they are inserted into the medullary cavity, which is the hollow part of the bone that contains marrow .
Post-Surgery Latency Period
Due to the imposed demands on the body by the procedure, patients must enter a latency period to promote rest and initiate the natural healing process. Typically, this rest period lasts up to a week, often including 2-3 days in the hospital. It is imperative the new bone begins to develop prior to the onset of the lengthening phase.
During this time, rehabilitation will also begin. Patients are instructed on proper techniques for mobility and daily activities to prevent further aggravation while simultaneously giving the patient time to acclimate to their increasingly restricted mobility.
Limb Lengthening Surgery: Distraction Phase
The Limb Lengthening Phase
The distraction phase, or the lengthening phase, is where the real magic happens. Throughout the period, the fixator will separate the bone segments incrementally. Generally, the rate of bone lengthening is approximately 1 millimeter (0.04 inches) per day, although this may vary depending on the patient and the bone being lengthened.
Quite simply, the lengthening is performed by adjusting the orthopedic device. This can be performed by the patient or a family member that has been instructed on the safe operation and procedure.
As the distraction process continues, the regeneration of bone and soft tissue fills in the gap, until the bone has reached its new, desired length. Based on a standard pace of 1 mm daily, it is normally expected that 2.5 cm (1 inch) of bone can be gained with each month of distraction.
Importance of Physical Therapy
In addition to regular assessments, physical therapy is a critical component of the recovery process. Normally, it will start immediately after being discharged from the hospital and should be performed daily.
Physical therapy is crucial to ensure the development of strength and mobility in the limbs. In response to lengthening bones, muscles are naturally stretched tighter and joint movement is restricted.
More frequent physical therapy promotes a better outcome and a shorter recovery period. However, even once the distraction phase has been concluded, it is imperative to continue physical therapy as directed into the consolidation phase.
Height Increasing Surgery: Consolidation Phase
The third phase is consolidation, during which the regenerate bone hardens and calcifies. This is the period in which the limb recovers to a fully healthy and functional state. The fixator must remain in place through the consolidation phase to support this process and ensure no further damage is sustained.
This process will take just as much time, if not more, than the actual leg lengthening process in the distraction phase. For example, if 2 months were required for the distraction phase, the consolidation phase should last at least 2 months.
Continued physical therapy should be a priority to assist with the natural recovery and return to normal operation. Further, healthy habits, including optimized nutrition, sleep, and increased activity (therapy or progressively walking with crutches as directed) will help with the recovery.
Stature Lengthening: Rod Removal
The final step in the process is the removal of the fixator, returning the patient to regular, unsupported function with their newly lengthened limb. With external fixators, a doctor will often provide a cast or brace for additional support. However, with internal fixators, these are not typically applied.
Of course, it is still imperative to pay close attention to the health and mobility, and ensure that proper care is taken to ensure the health and functionality of the newly lengthened limb, to be sure that the surgery was successful, and hopefully, positively life-changing!
Limb Lengthening Limitations
It is important to note that there are limitations to the rate of lengthening and total lengthening possible. It may be tempting to try and expedite the process or increase total lengthening, but attempting to do so comes with increased risks and potential consequences.
First, the distraction phase must not occur too slowly. If it does, regenerate bone may harden before the treatment is completed. If this premature consolidation occurs, lengthening will no longer be possible without further surgery.
Alternatively, if bone is lengthened too quickly, there will be insufficient bone regeneration. This will inevitably result in complications with strength, alignment, and weight bearing potential, while significantly increasing the risk of refracture.
Soft tissue lengthening may also become a concern if physical therapy is not performed with appropriate frequency and intensity. The tightening of muscles and ligaments may lead to health and performance issues, potentially requiring additional surgery.
Finally, it should be noted that bones can typically only be lengthened 2 inches (5 cm) in a treatment. Additional lengthening, although possible, increases the risk of complications.
Leg Lengthening Methods
There are numerous methods of limb lengthening with varying pros and cons. Each of these methods will be briefly explained in this section. In the subsequent section, an overview of the pros and cons will be provided for comparative purposes.
External Methods of Limb Lengthening
This article will address the four most common and relevant external methods. Other notable external fixators include Salamehfix (SLDF), Micro-Wound, Taylor Spatial Frame, and the Modular Rail System.
One of the most famous and popular external devices, the Ilizarov Apparatus (or ring fixator) is a circular frame consisting of two or three rings that form a scaffold around the limb. Screws and wires connect the apparatus to the bone, which has connecting rods to stabilize the rings.
This cut leaves the inner bone marrow intact. During the distraction phase, screws on the apparatus are turned, extending the distance between rings and stretching the bones apart slowly. Once the distraction phase is completed, the apparatus will remain in place to provide stability during the consolidation phase.
While this is the cheapest lengthening option, it can be time-consuming and is very restrictive. The large Ilizarov Apparatus must be worn the entire time and with more time invested, there are higher risks of complications in pin tract infection, soft tissue tethering, decreased joint Range of Motion (ROM), and discomfort.
A 2014 study that reviewed medical records of patients that used the Ilizarov Apparatus between 1983 and 2006 assessed risks and rewards . 37% of patients experienced complications (soft tissue or bone-related), however, the final outcome was rated as excellent for 55% of patients and good for 40%. Only one patient out of 131 total experienced a poor final outcome (0.77%).
LON (Lengthening Over Nail)
Lengthening over Nail (LON) uses both a ring fixator and an intramedullary nail. To prepare the device, a hole is cut through the bone during surgery for the placement of an intramedullary nail (inside the bone cavity). After the nail is placed inside the bone’s shaft, it is secured at the proximal end (nearest the center of the body) using screws. At this time, the external fixator (the ring) is attached.
Distraction proceeds similarly using the Ilizarov Apparatus, exactly as described above. The purpose of the intramedullary nail is to provide weight bearing support during consolidation.
Although an additional procedure is required to remove the intramedullary nail, and there is a higher infection rate, it reduces the time required for consolidation due to the increased support. Additionally, the nail helps to ensure proper bone alignment and prevent complications from a purely external method.
A 2019 study assessed the effectiveness of using intramedullary nails in 28 patients (Note: This study does not reference the effectiveness of the external fixator) . After a median of 8 years post-operation, they observed 8 excellent results, 15 good results, 4 fair results, and 1 poor result. Average lengthening and time for consolidation were 5.8 cm and 6 months for femurs and 4.8 cm and 4.5 months for tibiae.
LATN (Lengthening and then Nailing)
Lengthening and then Nailing (LATN) is a slightly different approach to LON. The exact process for the Ilizarov Apparatus (described above) is followed to apply the external fixator and perform the distraction phase. Unlike LON, the intramedullary nail is not inserted into the bone during the phase.
The key difference is that after the distraction phase is completed, the external fixator is removed and the intramedullary nail is inserted for consolidation. This process is the same as described above for LON.
Similar to LON, this process reduces the time required for the external fixator to be used, as the intramedullary nail supports the consolidation phase and provides improved stability. This is advantageous over LON due to fewer infections and the easier treatment of infections, with only one fixator present at a time. Consequently, there is a greater possibility of bone misalignment during the distraction phase due to the lack of internal support.
A 2011 study of 32 patients observed an average lengthening of 7.6 cm with a mean follow-up duration of just over three years (38.7 months) . High pain was observed after week one (9.3 on the Visual Analogue Scale (VAS)), but was reduced to 0.3 one year after intramedullary nailing. 91% of patients were satisfied after week 6 and 94% at a one-year follow-up.
Unilateral External Fixator (Monorail Fixator)
A Monorail Fixator functions similarly to the Ilizarov Apparatus but with a different structure. Instead of rings that surround the limb like a scaffold, a single bar runs parallel to the limb and is attached with pins to the bone. Just like with the LON method, this external fixator can also be used with an intramedullary nail.
With fewer pins, the unilateral external fixator results in fewer scars than the Ilizarov Apparatus is more comfortable, and may even be worn under clothes. However, pin site infections are common and large pin holes required for stability may result in significant discomfort.
In comparing monolateral external fixation (group A) with internal lengthening nails (group B), a 2019 study observed similar lengthening (A: 5.6 cm, B: 4.8 cm) and healing metrics between the two methods . However, the intramedullary nail resulted in a superior range of motion, a lower rate of complications, particularly with reduced pin site infections. Therefore, an internal fixator may be preferred over the use of an external monorail fixator.
Limb Lengthening Surgery – Internal Methods
Similar to the external methods, there are a variety of different options for internal methods. Notable methods that will not be discussed in detail include the Albizzia Nail (including the updated Guichet Nail and Betzbone), the Bliskunov Nail, and Fitbone.
Intramedullary Skeletal Kinetic Distractor (ISKD)
The Intramedullary Skeletal Kinetic Distractor (ISKD) is a kinetic clutch mechanism designed by Dr. J. Dean Cole. Two rods are screwed together to form the telescopic nail and inserted into the bone cavity. The clutch mechanism is activated by small rotational movements by the patient, enabling the nail to lengthen. To ensure accurate and measurable distraction, it can only be rotated in one direction and a monitor tracks the total distraction at all times.
Using an internal fixator such as the ISKD, there is generally improved patient comfort and tolerance in comparison to external methods. This method also offers fewer scars and a reduced risk of health issues, including infection and joint stiffness.
However, mechanical failures are common. Mechanical failure may lead to additional surgery and issues with the distraction rate, resulting in increased complications, including premature consolidation, weak ossification, and pain. Additionally, internal fixators may lose 2-7 mm in height gain during the removal of the femoral screws (a process called dynamization).
In 2012, in a review of 16 cases using ISKD, a mean length increase of 35 mm was observed with no infections, malunion or joint contractures . They concluded that ISKD is an effective treatment option, albeit with treatable complications. Alternatively, a 2014 study concluded that “surgeons should avoid use of this nail” due to high rates of complications (in 53% of patients) and difficulties with rate control .
The PRECICE(™) nail uses a magnetic field generator (an external remote controller) to control the internal fixator from outside of the body. Internally, the fixator features a titanium telescopic rod that is secured into the bone’s cavity with screws. Inside is a magnetic motor that generates the necessary force to lengthen the rod. The external magnetic field is used to power the internal motor, simply by pressing against the skin on the outside of the leg for brief intervals throughout the day.
Similar to the ISKD, this method reduces the risk of infection, joint stiffness, and pain while improving overall tolerance and comfort. It is also considered by many to be more reliable than comparable options, including the ISKD. However, it can be a costly treatment, it is not not weight bearing, and maximum lengthening is limited to 6.5 cm.
A 2017 study reviewed nine patients, of which seven achieved their lengthening goals (average 34.7 mm) . In the two cases that were unsuccessful, there was a loss of achieved length (20mm and 10mm) after the lengthening of the nail, possibly due to premature weight bearing that prevented complete bone consolidation.
In 2017, a review of various systems concluded that the PRECICE nail offered patients favorable outcomes compared to the ISKD system or an external Limb Reconstruction System (LRS) . Key findings were that the PRECICE system offered better range of motion and reduced rate of pin site infections.
STRYDE (On Recall)
Building off the PRECICE(™) System, NuVasive’s STRYDE is the third-generation limb lengthening system . Notable improvements include the increased capability for weight bearing thanks to a revamped stainless steel composition. Previous designs allowed for 30-50 pounds of weight bearing on each leg, whereas this new design permits 150-250 pounds per leg.
As of February 20, 2021, the STRYDE system has been on recall . This is the result of a series of adverse events reported, which are currently being investigated. The recall notice can be read here.
Choosing a Lengthening Method
There are many considerations when evaluating and selecting the appropriate leg lengthening treatment. Cost, time, risks, and the total lengthening desired, among other preferences, may influence the decision.
External Vs. Internal Fixation
In general, most external fixators are very similar in process and outcomes. The same can be said for the various internal nails, which differ slightly in design and outcomes.
When comparing internal and external methods, it often comes down to cost and risk. External methods are typically less expensive, but have a higher risk of health outcomes while being more painful and uncomfortable.
Therefore, internal methods are usually a better option, but they come at a greater price point. The common benefits of an internal fixator include:
- Lower risk of joint stiffness, infection, and pain
- Improved comfort and tolerance
- Fewer scars
- No soft tissue tethering
Pros and Cons Cheat Sheet
This section provides a cheat sheet of the seven methods addressed in this article for referencing and comparison. It should be noted that this is not an exhaustive list or summary. It is recommended to speak with a medical professional for medical advice to ensure proper treatment and the best outcomes.
Table 1. Overview of Benefits and Risks for Common Limb Lengthening Methods
|Ilizarov Apparatus||External||Cheapest option; no additional surgeries after removal||Pin tract infection; decreased ROM in joints; bone fracture after frame removal; discomfort; soft tissue tethering|
|LON (Lengthening Over Nail)||External||Reduced time wearning an external fixator; low risk of regenerate bone misalignment; relatively few complications compared to other methods||Pin site infrection; requires acute deformity correction; deep intramedullary infection; additional surgery required; discomfort; soft tissue tethering|
|LATN (Lengthening and then Nailing)||External||Reduced time wearning an external fixator; quick bone healing rate; low rate of infections; infections are easily treated; good stability during consolidation||Repeated adjustments; risk of refracture; discomfort; soft tissue tethering|
|Unilateral External Fixator (Monorail Fixator)||External||Fewer pins = fewer scars; can be worn under clothes; effective for smaller limbs||Fewer but larger scars; pin site infections; low stability; pain (caused by pinhole sites)|
|Intramedullary Skeletal Kinetic Distractor (ISKD)||Internal||Standard benefits of internal devices||High rate of mechanical failure (requiring additional surgery); difficult to control distraction rate; risk of refracture; rising costs; may lose 2-7mm height gain from dynamization|
|PRECISE System||Internal||Standard benefits of internal devices; reliable (more than Fitbone or ISKD)||Expensive; longer recovery; muscle weakness; maximum 6.5cm lengthening|
|STRYDE||Internal||Same as PRECICE System; Greater load bearing capability (150-250 lbs per leg)||Reported adverse events (pain and bony abnormalities); currently on recall (as of Feb. 20, 2021)|
With this information, you can be better prepared to assess the lengthening options available to you, and make an informed decision that offers the highest degrees of safety and satisfaction. With time and work, achieving the height you have always dreamed of is within reach!
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