Methods of Bone Fixation in Limb Lengthening

Author: Dimitrios Giotikas MD, PhD

When a bone breaks ( either after an accident or when surgically osteotomized), it  must be securely fixed with devices or implants in order to create optimum mechanical conditions of stability for the bone to heal. In distracton osteogenesis the fixation device, in addition to mechanincal stability, must be also able to move the fixed bone in a controllled and predictable way to produce the lengthening.

Initially, Ilizarov used what later became the famous ” Ilizarov apparatus” which is a circular external fixator frame. External circular frames where not without problems, so alternative internal implants (i.e. nails)  were gradually developed.  Nowadays, the most commonly used fixation devices in limb lengthening are the following:

Internal Implants

STRYDE nail is an internal fixation device;this means there is no hardware outside of the body.

It is inserted percutaneously through small stab incisions  and it is locked with screws  below and above the osteotomy in order to provide rotational stability.

Right femur, Stryde nail, 2.5 months after surgery

The newly released STRYDE Limb Lengthening and Compression System represents Nuvasive’s  latest advancement in the PRECICE family of implants.  This 3rd generation advanced solution builds upon the reputation and efficacy of the PRECICE proprietary technology.

Stryde was commercially released in 2018 and introduced in the European Union in January 2019. Athens BJR hase been one of the first centres that the nail became available to.

Stryde is made of stainless steel. STRYDE Benefits include:
• 400% increased post-operative weight bearing (vs. PRECICE)
• Reinforced internal mechanism
• Customizable lengthening protocol
• Novel PRECICE magnetic technology
• Up to 80mm of distraction
• Nail may be reversed

The key to the NuVasive platform technology is the magnetic interaction between the PRECICE STRYDE intramedullary nail and remote control. The proprietary technology includes a complex internal gear system remotely activated and controlled by permanent magnets. This 3rd generation advancement in limb lengthening and compression allows for precision control and the ability to non-invasively customize treatment.

External Remote Controller (ERC)
The ERC is a portable, hand held unit that precisely lengthens or shortens the STRYDE nail through the touch of a button. The ERC prescription is customized by the physician to meet the needs of each patient. The ERC is
designed to be used in a clinic setting or from the comfort of the patient’s home.

STRYDE Weight bearing properties : 150lbs for the 10.0mm diameter
implant, 200lbs for the 11.5mm diameter implant and 250lbs for the 13.0
mm implant.

References

  1. Data on File. PRECICE STRYDE Max Patient Weight Assessment. Report LR0838-1
  2. Herzenberg JH, Standard SC, Specht SC. Limb lengthening in children with a new,
    controllable internal device. European Paediatric Orthopaedic Society (EPOS);
    April 17-20, 2013; Athens, Greece.

Precise-2 is the previous generation of PRECISE limb lengthening family of products.  Precise-2 was introduced by Nuvasive in 2012.

The main disantvantage of Precise-2 , compared to the newer Stryde, is that it  doesn’t allow full weight bearing post-operatively. Although this is reasonably well tolerated in case of unilateral limb lengthening, (or bilateral upper limb) it is not very comfortable and efficient in cases of bilateral lower limb lengthening such as for cosmetic reasons.

Because of Precise-2’s weight bearing restrictions, we now offer Precise-2 in selected cases  only and after appropriate consultation. ( See more in Limb Lengthening Options and Financial Considerations.)

Since the 1970s, several intramedullary lengthening nails have been developed to avoid various complications caused by long periods of external fixation.

The following devices have been the most clinically known: the Fitbone® (WittensteinIntens, Igersheim, Germany), the Albizzia® (DePuy, Villeurbanne, France), the Intramedullary Skeletal Kinetic Distractor (ISKD®; Orthofix Inc., Lewisville, Texas, USA). Each of the lengthening nails has its own characteristic mechanical mechanisms, which could also bring distinct complications.

However, many of these have showed some issues associated with the lengthening mechanism or strength of the nail which resulted in nonoptimal results.

These implants heve not been used in our centre and are not offered to our patients. They are mentioned here for the purpose of completeness only.

References.

DH Lee,  S Kim, JW Lee, H Park,T Y Kim, and HW Kim.  A Comparison of the Device-Related Complications of Intramedullary Lengthening Nails Using a New Classification System. Hindawi,BioMed Research International, Volume 2017, https://doi.org/10.1155/2017/8032510

External Devices

The Ilizarov circular frame consists of rigid ( metallic or, most recently, carbon fliber) rings which are connected to each other with rods.  In the context of

 

limb lengthening, two rings are placed around each part (segment) of the bone (i.e above and below the level of the osteotomy).  The rings work as a scaffold on which the bone is fixed with tensioned fine wires and half pins.  The rods that connect the two bone segments  can be lengthened ( or compressed) with the turning of nuts.

The Ilizarov circular frame  has passed the test of time and it is the most well-studied device in distraction osteogenesis. Nevertheless, it does have its own shortcomings, such us pin-site problems and difficulty with walking, washing and performing daily tasks. Because of these problems it is not well tolerated in the thigh.

In Athens BJR, we do not use circular frames for femoral limb lengthening for any reason.

When we use ilizarov type circular frames in the tibia, we prefer to use the hardware of TSF from Smith & Nephew. The reasons for  that are:

  • The rings are made of carbon fibers so they are lighter.
  • The lengthening device of the frame (graduated telescopic blue rods) allow for a more controlled, easier ( no need to us spanners) and less confusing lengthening for the patient,  day in day out.
  • We reduce unnecessary device variabiality of  in our center and this contributes to increased safety.

References

  1. C. Fenton, D. Henderson, A. Cherkashin, M. Samchukov, H. K. Sharma. COMPARISON OF THE MECHANICAL PROPERTIES OF THE TL-HEX AND TSF FRAMES. Orthopaedic ProceedingsVol. 100-B, No. SUPP_8

This section is under construction.

References

This section is under construction.

In addition to the methods above, which are either purely external or purely internal, combined methods of fixation have been also proposed:

Combined Methods

Limb lengthening with purely external fixation devices entails that the frame has to remain in situ for the whole consolidation period leading to frame times of up to 2 months per cm of lengthening. This prolonged time in a frame confers several disadvantages. First, there is a greater chance of complications like pin-tract infection and decreased range of motion in the surrounding joints. Second, it may have a psychological effect on patients, increasing frustration and decreasing compliance. Finally, when the frame is removed, there is an 8 to 9.4% reported risk for fracture of the regenerated bone due to the lack of any internal stabilization.

LATN was introduced as an idea to reduce the external fixator time and avoid some of the reported  limitations and risks of LON including infection, need for acute deformity correction when a deformity is present and inability to distract the bone and achieve the desired lengthening.

External fixation is used for lengthening during the distraction phase and when lengthening is completed then the patient is taken back to theatre and  an intramedullary nail is inserted and the frame is removed. The external fixator is applied so that an intramedullary nail can be inserted while the frame is in place, however, without contact between the internal fixation and the external fixation pins and wires.  Once length has been achieved, a reamed locked intramedullary nail is inserted across the regenerate bone and the frame is removed. The intramedullary nail supports the bone during the consolidation phase allowing removal of the external fixator after the distraction phase of lengthening.

LATN is now the preferred method (instead of LON) in our centre for bilateral cosmetic tibial lengthening, when purely internal methods are excluded because of financial and funding limitations or when simultaneous correction of bone deformitiy is required.

References
S. Robert Rozbruch, MD, Dawn Kleinman, BA, Austin T. Fragomen, MD, and Svetlana Ilizarov, MD. Limb Lengthening and Then Insertion of an Intramedullary Nail: A Case-matched Comparison. Clin Orthop Relat Res. 2008 Dec; 466(12): 2923–2932.

LON is now used in our center only in cases of unilateral femoral or tibial lengthening after appropriate counselling , when purely internal methods are excluded because of financial and funding limitations.

LON was introduced as an idea to reduce the time spent on an external fixator and the related problems. External fixation is safe, but the consolidation phase tends to take too long.  The prolonged fixator time puts the patience of the patient to the test and, when applied to the femur, this prolonged duration tends to increase knee stiffness.

Moreover, eccentric loading of bones in the limb creates a  tendency for axial deviation of the regenerate and malunion.  Loosening of the fixation pins, instability of the fixator and tightness of muscles increase the tendency for axial deviation in the lengthening phase.

Combining IM fixation with the Ilizarov fixator firstly adds to the stability of the construct. The next benefit of the addition of the IM nail is the prevention of axial deviation during the fixation period and also after removal of the fixator over the long term. This was proved in our series with very low rates of axial deviation.

The greatest concern with LON technique has been the risk of deep bone infection due to close proximity of external pins and the nail. With great care in pin insertion and postoperative care we have not faced this problem in our series. However, the literature has mentioned this problem in the series of Simpson who had three deep infections in twenty LON surgeries. Kristiansen reported giving up on this method to revert back to the Ilizarov technique due to many complications.

 

The surgical technique of the LON procedure include:

  • Preparation (drilling holes) of the osteotomy site.
  • Completion of reaming of the intrmedullary canal (to prepare it for the nail).
  • Partial application of the external frame (with reamer insitu as a reference to guide external pins and wires clear from the nail.)
  • Completion of osteotomy.
  • Insertion of the nail and proximal locking only.
  • Completion of external frame construct as needed

When the distraction phase is completed, the patient is taken back to theatre where the  nail is locked distally with to screws and the external frame is removed. This is a minor procedure which is done as a day case and the patient leaves the hospital on the same day.

References

  1. Chaudhary M. Limb lengthening over a nail can safely reduce the duration of external fixation. Indian J Orthop. 2008 Jul-Sep; 42(3): 323–329.
  2. Paley D, Herzenberg JE, Paremain G, Bhave A. Femoral lengthening over an intramedullary nail: A matched-case comparison with Ilizarov femoral lengthening. J Bone Joint Surg Am. 1997;79:1464–80.
  3. Min WK, Min BG, Oh CW, Song HR, Oh JK, Ahn HS, et al. Biomechanical advantage of lengthening of the femur with an external fixator over an intramedullary nail. Pediatr Orthop B. 2007;16:39–43.
  4. Simpson AH, Cole AS, Kenwright J. Leg lengthening over an intramedullary nail. J Bone Joint Surg Br. 1999;81:1041–5. 
  5. Kristiansen LP, Steen H. Lengthening of the tibia over an intramedullary nail, using the Ilizarov external fixator: Major complications and slow consolidation in 9 lengthenings. Acta Orthop Scand. 1999;70:271–4.
  6. Kocaoglu M, Eralp L, Kilicoglu O, Burc H, Cakmak M. Complications encountered during lengthening over an intramedullary nail. J Bone Joint Surg Am. 2004;86:2406–11.