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Limb Lengthening
What is Limb Lengthening ?
Limb lengthening stands as a surgical intervention aimed at elongating bones in the arms or legs. The procedure initiates with the separation of the bone through osteotomy, followed by the gradual and precise pulling apart of bone segments, a process known as distraction. This intentional manipulation creates a space between the bones, referred to as the osteotomy gap, where new bone tissue develops. The gradual separation of bone segments triggers bone regeneration, resulting in an increase in overall bone length. The effectiveness of limb lengthening depends on the body's natural ability to grow new bone, supported by the surrounding soft tissues, ligaments, fascia, blood vessels, and nerves. The operative technique relies on the utilization of the principle of distraction osteogenesis to achieve effective limb lengthening.
How does the Limb Lengthening work?
Limb lengthening and deformity correction operate based on the principle of distraction osteogenesis. When a bone breaks (fractures), the natural healing process involves the regeneration of new bone tissue at the fracture site to restore the bone's integrity. In limb lengthening, this principle is harnessed through a surgical procedure that involves cutting the bone in two (osteotomy) and gradually separating the two bone sections. This intentional separation creates a space where new bone, known as callus, grows to bridge the gap.
The procedure unfolds in three main steps:
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Osteotomy: A surgical cut is made to separate the bone into two segments.
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Distraction: Using orthopedic devices such as internal nails or external fixators, the two bone segments are slowly pulled apart at a controlled rate and rhythm.
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Consolidation: The new bone tissue gradually fills the gap (osteotomy gap) and undergoes mineralization and hardening.
Typically, bone segments can be lengthened by approximately 10-15% of their original full length, though this rate may vary among individuals. During the lengthening phase, bone ends are usually separated at an average rate of about one millimeter per day. Following the distraction phase, the newly formed bone undergoes mineralization and consolidation, a process during which soft tissues like nerves, muscles, vessels, and skin stretch and adapt to the changes occurring during limb lengthening.
Limb Lengthening Surgery
During the surgical procedure, the surgeon initiates the process by performing an osteotomy, which involves cutting the bone to create two distinct segments. Simultaneously, an orthopedic lengthening device is applied to the bone. These devices fall into two categories: internal devices, like the PRECICE nail, are inserted into the bone, while external fixators, such as the monorail fixator or the Circular (Ilizarov) frame fixator, remain outside the body. The internal method involves the insertion of an intramedullary nail, osteotomy, and fixation of the nail. On the other hand, the LON method encompasses the insertion of an intramedullary nail, osteotomy, and the attachment of an external fixator. Both methods are characterized by minimal incisions made by the surgeons.
Limb Lengthening Periods
Latency (Hospital) Period
The time spent in the hospital between the surgery and the beginning of the lengthening process is referred to as the latency period. During this phase, the formation of callus, which is new bone tissue, is anticipated between the ends of the osteotomy bone. There is no lengthening during this period. Once a satisfactory level of new bone tissue has developed, the lengthening process is then started. Typically, the latency period lasts 5-10 days.
Distraction (Lengthening) Period
The duration from the initiation of the lengthening procedure until the desired length is achieved and the process is finished is known as the consolidation phase. During this period, the patient makes adjustments to the orthopedic device, gradually pulling apart the two bone segments. This deliberate and gradual separation of the bone segments is termed distraction, essentially meaning "pulling apart." As the two bone segments are gently pulled apart, new bone begins to form in the space created between them. Typically, the rate of lengthening is around 1 millimeter per day.
Consolidation (Healing) Period
Following the distraction phase is the consolidation phase, during which the newly generated bone gradually solidifies. The new bone isn't considered fully "healed" until it has hardened and calcified. Throughout the consolidation period, the new bone tissue gains the necessary hardness and durability to bear weight. Once the regenerate bone has completely consolidated, the intramedullary nail can be removed.
Limb Lengthening Methods
In cosmetic limb lengthening, there are two main methods: internal (PRECICE) and LON (combined) methods. In the internal method, the surgeon places special nails inside the bone that can extend its length, and it's a completely closed procedure with no external device attached to the bone. On the other hand, in the combined method, the surgeon not only inserts an intramedullary nail into the bone but also attaches an external device (external fixator) from outside the body to aid in the lengthening process.
LON with Circular Fixator
The LON method, a combined approach in cosmetic limb lengthening, involves the insertion of an intramedullary nail into the bone. Simultaneously, an external fixator is attached to the bone from the outside.
Which bones can be lengthened in height lengthening surgery?
Femur Lengthening
Lengthening surgery can be performed on the thigh (femur) bone, utilizing either internal or combined techniques. In the LON method specifically designed for the femur, the Monorail fixator is the suitable external device. The bone union rate for the femur is generally faster than that of the tibia. Typically, the lengthening rate for the femur is around 1 millimeter per day. It's important to note that the safety limit for femur lengthening is set at 8 centimeters.
Tibia Lengthening
Lengthening surgery can be performed on the shin (tibia) bone, utilizing either internal or combined techniques. In the LON method designed for the tibia, the Circular (Ilizarov) frame fixator is the appropriate external device. Additionally, the fibula is extended along with the tibia. The typical lengthening rate for the tibia is around 0.75 millimeters per day. It's essential to be aware that the safety limit for tibia lengthening is generally set at 6 centimeters.
How to do the Lengthening ?
LON (Combined)
Method
In the LON method, daily limb lengthening is achieved using an external fixator, typically at a rate of 1 millimeter per day. This daily extension is usually divided into four increments, spaced every 6 hours. When it's time for lengthening, the patient completes the process by turning the fixator apparatus 90 degrees. This rotation is quiet and straightforward, allowing patients to easily perform it themselves. The lengthening process is finished once the target length is achieved. This method provides a controlled and patient-friendly approach to gradually reaching the desired limb length.
PRECICE (Internal)
Method
In the Precice system, the lengthening process is facilitated by the External Remote Control (ERC) system. The ERC device is positioned in a specific marked area on the patient's leg, and the lengthening is executed with a single button, offering a remarkably easy and comfortable experience for the patient. The Precice system is noted for its excellent rate control, and patients often report minimal pain during the lengthening process. This user-friendly and technologically advanced approach provides patients with a convenient and controlled means of achieving their desired limb length.
Limb Lengthening Physical Therapy
Physical therapy is a crucial part of limb lengthening, a challenging and lengthy process with potential complications. The goal is to minimize these issues and improve outcomes by maintaining and increasing range of motion, strengthening muscles, preventing contractures, and enhancing overall functionality.
During limb lengthening, where the bone grows at a rapid rate of 1 mm per day, the surrounding soft tissues need to adapt accordingly. However, these tissues can't naturally stretch at such a fast pace, leading to complications, especially in muscles and nerves. Increased tension in nerves can cause pain, loss of sensation, and reduced movement, while muscle tension can restrict joint movement and weaken strength. To address these challenges, effective physical therapy is crucial.
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LON Method
Weightbearing Protocol​
During the Distraction Period, external fixators bear the full body weight throughout the lengthening process, showcasing their high load-carrying capacity. In the LON method, patients have the capability to walk with full weight bearing, although using a walker is advised to maintain balance during this period.
In the Consolidation Period, the intramedullary (IM) nail, known for its robust load-bearing capacity, allows patients to walk with full weight bearing. However, it is recommended to use a walker or crutch until the callus tissue attains sufficient hardness, which typically takes 1-2 months. This precautionary measure helps ensure stability and support during the initial stages of consolidation.
PRECICE Methods Weightbearing Protocol​
During the Distraction Period, external fixators bear the full body weight throughout the lengthening process, showcasing their high load-carrying capacity. In the LON method, patients have the capability to walk with full weight bearing, although using a walker is advised to maintain balance during this period.
In the Consolidation Period, the intramedullary (IM) nail, known for its robust load-bearing capacity, allows patients to walk with full weight bearing. However, it is recommended to use a walker or crutch until the callus tissue attains sufficient hardness, which typically takes 1-2 months. This precautionary measure helps ensure stability and support during the initial stages of consolidation.