THE ERC DEVICE GIVEN TO EACH PATIENT
The STRYDE is the most advanced lengthening device available today. The STRYDE has excellent rate control and patients report minimal pain associated with lengthening. The STRYDE and Precice are the only devices on the market that has a reverse mechanism, which is a very important safety feature. The device lengthens similar to the way an antenna extends. An external remote control (ERC) is used to rotate a magnet inside the nail. This in turn rotates gears which turn a drive screw, which extends the telescopic nail.
The STRYDE, spearheaded and developed by Dr. Paley, was designed with the special considerations of the stature lengthening patient in mind. The STRYDE can lengthen a maximum of 5, 6.5, or 8 cm depending on the length of the implant used. Weight bearing up to 150, 200, and 250 lbs is allowed for nail diameters of 10, 11.5, and 13 mm respectively.
The strength of the STRYDE is up to 4 times stronger than the PRECICE, Furthermore, the driveshaft connection strength has been increased 3 times more than the PRECICE, The STRYDE is currently the only FDA-approved device on the market.
HEIGHT GAINS WITH STRYDE
Most patients desire 3 inches (8 cm) of stature gain and some more than that. The STRYDE can lengthen 8 cm. Patients who desire more length should consider a second lengthening of the other bone. For maximum length with two lengthenings, we recommend femurs first and tibias second. The total height gain with two separate lengthenings is as high as 13 cm (8 cm in the femurs and 5 cm in the tibias). Greater length is not as well tolerated in the tibia and Dr. Paley highly recommends not to exceed 5 cm in the tibias, as it can lead to serious complications. Of course the cost of two lengthening is twice that of one lengthening. Although the device can lengthen as high as 8 cm, not every patient can safely achieve that much length. We will only allow lengthening to the tolerance of the patient’s bone and soft tissues. Our dictum is to never sacrifice safety and function for greater length.
The limiting factor to lengthening is usually the soft tissues. The risk of complications from lengthening increase dramatically with increased length. In a previous study we performed we showed that lengthening up to 5 cm is a low-risk lengthening; between 5 and 8 cm is medium risk; ver 8 cm is a high-risk lengthening. If a patient desires more than 8cm of lengthening, it is much safer to lengthen the femur and the tibia each by 5 cm than to lengthen either bone by 10 cm. It is also much better for appearance and proportions.
HISTORY OF IMPLANTABLE NAILS
While it is commonly recognized that the Soviet Union produced the greatest limb lengthening contributions through the innovations of Ilizarov, few realize that implantable limb lengthening also takes its origin in the Soviet Union. Alexander Bliskunov from Simferopol, Ukraine first published his method in 1983. This was before most of the world had heard of Ilizarov. Bliskunov developed a telescopic lengthening nail that used a crank shaft connected to the pelvis to drive his mechanism and lengthen the femur. His technology was not available outside of the Soviet Union. Others soon developed other mechanisms to drive telescopic lengthening nails. Baumgart et al, from Germany developed a motorized nail in 1991 called the Fitbone. It lengthens in one direction only. Guichet and Grammont from France, developed a telescopic nail in 1994 using a ratchet mechanism which rotated the two segments of the nail through the callus of the bone. This was called the Albizzia system and later named the Guichet Nail or Betz Bone by the two surgeons who continued to use this first generations system that could also only lengthen but not go reverse.
Cole from the US used this concept to develop a double clutch mechanism to lengthen the ISKD (Intramedullary Skeletal Kinetic Distractor) device marketed by Orthofix. This was the first FDA-approved device in 2001 but was removed from the market in 2011 due to a high frequency of rate control problems. Soubieran from France developed the Phenix nail which was acquired by Smith and Nephew and renamed the Novus. Problems with its mechanism not generating enough force caused them to abandon this project. Ellipse developed the Precice nail with Stuart Green. It became the second FDA-approved implantable lengthening nail. It had the ability to go forward and reverse. The P1 nail was first implanted by Dr. Paley on Dec. 1, 2011.
Breakage of the nail and the mechanism were identified by Dr. Paley leading to the redesign of the nail by Dr. Paley and Ellipse to create the P2 which is used to this date. In 2016 Ellipse was acquired by Nuvasive. The problem with the P2 nail is that it only allowed limited weight bearing to avoid breakage. This is because it was made of titanium. Together with Nuvasive, Dr. Paley developed a stronger nail made of stainless steel called the STRYDE nail. Dr. Paley implanted the first STRYDE nail in May 2018. This is the ideal implant for stature lengthening. Dr. Paley also developed the newest device which is the GroPlate which is the first FDA approved fully implantable lengthening plate instead of a nail. Of interest Dr. Paley implanted the Albizzia nail in 10 cases in the 1990’s. He implanted 400 ISKD’s in the first decade of the 2000’s. Since 2011 he had implanted over 1200 Precice and STRYDE nails. Dr. Paley is the most experienced implantable limb lengthening surgeon in the US and in the world.