Internal Fixation Devices Overview & Analysis

In today’s world, doctors can effectively treat fractures, bone deformities, limb length discrepancies and even make people taller with internal fixation devices. People usually consider these superior to external devices, but the decision ultimately comes down to budget, the surgeons preferred methods, and what’s best for the patient.

Understanding how they work can be a daunting task, though – let us simplify it for you!

Internal Fixators Explained

When correcting deformities or in cosmetic limb lengthening, the surgeon usually breaks the bone and uses an internal fixator to hold it in the desired position until it’s allowed to heal or consolidate. If a broken bone is present, internal fixators can hold it in place without the hassle of a cumbersome external device – at least for the long term.

Internal Fixation Types

Thanks to modern medicine, we have access to an array of internal fixation devices to suit every patient’s unique needs, including plates, screws, wires, and nails. The main difference between these methods lies in how to implant them and how they hold the bone together.

Plates

An orthopedic plate is a minimally invasive device that heals fractures. The surgeon fixes it on the outside of the broken bone to keep it aligned and in place.

For limb lengthening, a plate, such as the PRECICE Plate, is used to lengthen the legs of pediatric patients since it doesn’t require inserting a nail into their tender bones.[1] Once a gap is made in the bone, and the plate is fixed to the outside or implanted, the patient can use an external remote controller to move the two pieces of bone apart slowly.

The PRECICE Plate is currently recalled but should be available by next year. It can safely lengthen by up to 6.5 cm.[2] They’re usually left in place once the bone fully heals.

Screws

Screws are the most common method used to heal fractures, but they play a role in limb lengthening too. Screws allow two pieces of bone to be held together and keeps them aligned so they can heal and consolidate once again.

Since the surgeon inserts them into the bone, they can be utilized either alone or with plates, rods, and nails. Screws don’t necessarily need removal, but they often are according to the surgeon’s discretion.[3]

Screws, in combination with nails, help avoid misalignment and improper healing of bones (malunions) during cosmetic limb lengthening since they help hold the bone firmly in place.

Wires and Pins

Wires and pins are usually used to fix bones temporarily or for smaller bones like those in hands or feet. They’re thin, smooth, stainless steel rods with a hook at the end, and the surgeon might thread these into the bone through the skin itself – also known as percutaneous pin fixation.

This process involves inserting the wire through the skin on one end of the limb and passing it to the other end. The surgeon then fixes the wire to an anchor known as traction, like a horseshoe with weights attached to it.[3]

When used as temporary fixators, they’re usually removed after about 4 four weeks and replaced with more robust fixation devices like plates or screws. They can even couple with external devices like the Ilizarov apparatus, an external fixator used to lengthen legs.

Pin site infection is a common side effect of wires and pins at the skin level, but antibiotics can quickly treat them.

Nails and Rods

Nails and rods are usually inserted into the bone marrow to hold the bone in place. The medullary cavity is the central part of the bone that houses red or yellow bone marrow. Since nails pass through this cavity, they’re also called intramedullary nails. “Intramedullary” means they lie within the medullary cavity.

Gerhard Küntscher first employed intramedullary nails to treat fractures in the femur during World War 2. The nail is implanted within the marrow and passes through both bones, allowing it to heal and consolidate over it.

Intramedullary nails allow patients to walk much faster than other internal fixators as they can bear weight, depending on the type of nail used. For cosmetic limb lengthening, the nail consists of the stationary part and the lengthening part. The surgeon cuts the outer part of the bone to form a gap. The marrow then receives the nail, and an external remote controller is used to gradually lengthen the nail and move the bone fragments apart at a rate of about 1 mm per day.

Once lengthening completes, the nail is allowed to stay inside until it calcifies. Doctors recommend removing the nail after the bone fully heals since it’s not yet known how it might react with the body in the long run.

Internal Fixation Devices

In regards to nails and rods, there are countless internal fixation devices that have come and gone.

While doctors have used many internal fixators like the Intramedullary Skeletal Kinetic Distractor (ISKD), the Fitbone, the Guichet Nail, and the Betzbone to heal fractures and lengthen limbs in the past, these are mostly outdated. Instead, the PRECICE and PRECICE STRYDE are the most popular, extensively tested, and reliable options on the market right now.

PRECICE

Developed by Dr. Dror Paley of the Paley Orthopedic and Spine Institute, the PRECICE is a titanium intramedullary nail primarily used for cosmetic limb lengthening. The PRECICE 2.2 is the latest in the line of PRECICE nails.

PRECICE can lengthen up to 8 cm at a time if implanted into the femur or the thigh bone. When lengthening the tibia as well, height gains can extend up to 14.5 cm[4] with multiple surgeries. The patient controls the lengthening rate through an external remote controller that reacts with the magnets sealed inside the nail.

How Long Does It Take?

One week after the surgery, patients can begin the lengthening process. The lengthening rate is limited to 0.5 mm to 1 mm a day to avoid soft tissue tightness. However, PRECICE is not weight-bearing, and patients will have to use a wheelchair and eventually a walker and crutches up to a year after the initial surgery, depending on how long it takes for the bone to heal.

The surgeon removes the PRECICE once the bone heals, and patients can walk normally again within a year if they keep up with physical therapy. However, it costs less than STRYDE, which may be a significant factor for many potential patients.

STRYDE

STRYDE is the next generation of internal fixation devices for limb lengthening. It’s comparable to Fitbone as it allows for complete weight-bearing even during the lengthening period.[5] Patients would only have to use a wheelchair for exceptionally long distances.

STRYDE is implanted and controlled in the same way as PRECICE. However, since the STRYDE nail is stainless steel, it doesn’t present any significant risk of nail breakage. Patients can begin walking the first day after the surgery, though this varies on an individual basis.

How Long Does It Take?

Patients recover faster after STRYDE lengthening as they’re able to walk from the very beginning. It provides the same height gains as PRECICE, making STRYDE the superior and preferable option for most patients.

The trade-off for more convenience is a higher budget, though – STRYDE lengthening costs at least $97,500 at the Paley Institute, and prices can soar up to $280,000 depending on the bones lengthened and the number of surgeries performed.[6]

Surgeons still consider rod removal to be necessary, adding to the already high costs. NuVasive has currently recalled STRYDE in the US and UK, but it should be back on the market sometime in 2022.

Risk, Benefits, and Recovery Analysis

Though internal fixators are much more convenient and inconspicuous than external devices, they carry a pose a risk for infection even when sterilized and implanted using proper surgical techniques. There’s also the possibility that an internal nail might break and require further surgery to fix, but this breakage is quite unlikely if patients follow their doctors’ advice. Not to mention, Nuvasive is making them stronger with each iteration.

PRECICE and STRYDE are the most reliable methods of leg lengthening on the market today because they’re much more robust, reliable and allow for a faster recovery than external fixators.

In the end, each method has its pros and cons, and what’s best for a fracture may not be ideal for limb lengthening. Besides, though internal rods are considered superior, external fixators are much cheaper and are great for trauma cases.

No matter which fixation device is chosen, whether internal or external, it’s always best to speak to a healthcare professional about which options are best for a given budget and a surgeon’s experience.

References

[1] NuVasive. (2020, September 9). NuVasive Expands Precice Portfolio with First-of-its-Kind Plate for Pediatric Limb Lengthening and Reconstruction Procedures. NuVasive. https://www.nuvasive.com/news/nuvasive-expands-precice-portfolio-with-first-of-its-kind-plate-for-pediatric-limb-lengthening-and-reconstruction-procedures/

[2] Kulkarni, R., Singh, N., Kulkarni, G. S., Kulkarni, M., Kulkarni, S., & Kulkarni, V. (2012, May-June). Limb lengthening over plate. Indian Journal of Orthopaedics, 46(3), 339-345. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377147/

[3] OrthoInfo. (2019, April 22). Internal Fixation for Fractures. OrthoInfo. https://orthoinfo.aaos.org/en/treatment/internal-fixation-for-fractures/

[4] Paley Orthopedic & Spine Institute. (2015, September 26). The PRECICE. Paley Orthopedic & Spine Institute. https://paleyinstitute.org/centers-of-excellence/stature-lengthening/the-precice/#/

[5] Robbins, C., & Paley, D. (n.d.). Stryde Weight-bearing Internal Lengthening Nail. Techniques in Orthopaedics, 35(3), 201-208. https://paleyinstitute.org/wp-content/uploads/Stryde-Weight-bearing-Internal-Lengthening-Nail.pdf

[6] Paley Orthopedic & Spine Institute. (2015, September 26). Costs & Financial Considerations. Paley Orthopedic & Spine Institute. https://paleyinstitute.org/centers-of-excellence/stature-lengthening/costs-financial-considerations/#/