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| EDITORIAL |
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| Year : 2016 | Volume
: 2
| Issue : 2 | Page : 61-67 |
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Evolution in long bone deformity correction in the post-Ilizarov era: External to internal devices
Reggie C Hamdy
Division of Paediatric Orthopaedics, Department of Paediatric Surgery, Shriners Hospitals for Children and Montreal Children's Hospital, McGill University, Montreal; Chief of Staff, Shriners Hospitals for Children - Canada Head, Division of Paediatric Orthopaedics, Vice Chairman, Department of Paediatric Surgery, Director, Limb Lengthening, Deformity Correction and Bone Regeneration Unit, Quebec, Canada
| Date of Web Publication | 16-Sep-2016 |
Correspondence Address:
Reggie C Hamdy
Shriners Hospital for Children, 1003 Boulevard Decarie, Montreal, QC H4A 0A9
Canada
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2455-3719.190703
How to cite this article:
Hamdy RC. Evolution in long bone deformity correction in the post-Ilizarov era: External to internal devices. J Limb Lengthen Reconstr 2016;2:61-7 |
Since 1951, the innovative work of Prof. Gavriil Ilizarov in distraction osteogenesis revolutionized the management of long bone deformities. [1],[2] For the first time in history, complex deformities could be corrected, non-unions healed, short limbs lengthened, and massive bone defects and deficiencies replaced by new, viable, and vascularized bone. This great pioneer, Gavriil Ilizarov, also known as "the magician from Kurgan" [Figure 1] was a self-taught orthopaedic surgeon by necessity. In the early 1950s he invented a circular external fixator consisting of stainless steel (evolved more recently to carbon fibres) rings placed around the limbs, interconnected with four straight rods and transfixing soft tissues and bones with tensioned metallic wires [Figure 2]. He initially used his circular fixator to stabilize fractures. Then he introduced the principles of "tension stress" and distraction osteogenesis. He was the first to discover that under controlled and gradual distraction following corticotomy of a long bone, new bone will be formed in the distracted gap. Further refining his circular frame, Ilizarov developed olive wires and hinges that helped in reduction and correction of deformities, by controlling the position of the proximal and distal fragments. By using these principles, he expanded the use of external fixators to gradual correction of deformities, lengthening short bones, and bone transport. For many years, he treated thousands of patients in a remote town of Western Siberia. Unheard of in the Western World, his discoveries and techniques were introduced beyond Kurgan only in the early 1980s after he successfully treated a famous Italian explorer and alpinist Carlo Maori for a tibial non-union. Soon, almost every limb lengthening and deformity center worldwide adopted the technique of distraction osteogenesis and the circular fixators. Many conditions that were previously considered untreatable could now be addressed with Ilizarov discoveries. The legacy of this giant is immeasurable; his impact on the management of long bone deformities is monumental. His discoveries and innovations led to the birth of the specialty of limb lengthening and reconstruction surgery and a whole generation of Ilizarovians. | Figure 2: Components of the Ilizarov circular fixator (Ilizarov Museum, Kurgan)
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Although the final outcome was excellent in almost all cases, several problems with the technique of distraction osteogenesis were identified including the difficulty in placing the hinges for correction of complex deformities, especially rotational ones, and the long period of time the external fixator has to be kept on until the newly formed bone in the distracted gap consolidates. This long period could lead to numerous medical, social and financial problems for the patient, family and health care institutions. This prompted researchers to seek modifications to the Ilizarov frame, to develop new external fixators, and to explore other techniques in deformity correction and lengthening with minimal use of external fixators and more internal fixation.
| The Development of Hexapod Fixators | |  |
The use of hinges in the Ilizarov frame to correct deformities could be difficult and time-consuming, especially when dealing with complex and rotational deformities such as correcting deformities in more than one plane simultaneously. This led to the development of hexapod fixators and "virtual hinges." The first hexapod fixator in North America was developed by Dr. Charles Taylor in 1991 (patented in 1997), based on the principle of the Gough-Stewart platform [Figure 3]. The Taylor Spatial Frame [3] consists of two aluminium or carbon fibre rings connected with six telescoping struts that can be independently lengthened or shortened relative to the rest of the frame, thus allowing correction in six different axes [Figure 4]. Web-based software is used to enter all necessary data (deformity parameters, mounting parameters, and other data regarding rings and struts). A daily schedule for correction of the deformity is thus created and given to the patient. These virtual hinges replace the standard hinges of the Ilizarov ring. The accuracy of the correction is directly related to the accuracy of the data in the software. The Taylor Spatial Frame allows multiplanar correction simultaneously. Although this hexapod system was very quickly adopted in numerous countries, its prohibitive cost renders its use on a worldwide basis somewhat restricted. Other hexapod systems that have been developed include Truelok Hexapod [Figure 5] - based on the Truelok circular fixator [4],[5] and the Ortho-SUAV frame [Figure 6]. [6] Following the termination of the Taylor Spatial Frame patent in 2015, the world witnessed and continues to witness an explosion of newly designed Hexapod External Fixators. | Figure 4: (a) Showing placement of hinges at apex of deformity using a standard Ilizarov frame for correction of varus deformity of proximal tibia, (b) Taylor Spatial Frame construct for correction of the same deformity
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 | Figure 5: TrueLok Hexapod fixator. Hinges are placed outside the rings (in the Taylor Spatial Frame, the hinges are inside the rings)
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 | Figure 6: Ortho - SUAV external fixator, showing only 3 struts connected to the rings
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| The Development and Refinement of Existing Monolateral External Fixators | | |
DeBastiani popularized the use of monolateral fixators for limb lengthening, deformity correction, and bone transport. [7] He further refined the concept and technique of dynamization. Unilateral fixators are much less cumbersome than circular fixators especially when used in the femur; however they are more liable to cause angular deviation of the regenerate. The versatility of these fixators has been increased by the addition of ball and socket joints [Figure 7] and special clamps (swivel, translational, multiplanar) and angular and rotational templates that allow correction of complex and multiplanar deformities, both acutely and gradually [Figure 8]. Unilateral fixators have now replaced circular fixators in the management of many deformities especially in the femur. [8] A more complex type of monolateral fixator, the Multi-Axial Correction System includes two hinges in its design. [9] Although it could be used in many sites, the most popular use of this device is for cases of Blount's disease in the proximal tibia [Figure 9]. Hybrid fixators, combining both rings and monolateral bars, have also been developed [Figure 10]. | Figure 8: Monolateral rail fixator with clamp for correction of angular deformities
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 | Figure 10: Hybrid fixator, including Sheffield circular ring and component of unilateral fixator
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| Introduction of Half Pins Instead of Wires | | |
Half pins have been introduced as an alternative to wires. They minimize soft tissue transfixion. The recent introduction of hydroxyapatite-coated pins has helped decrease the incidence of loosening and infection.
| Development of New Techniques to Reduce External Fixator Time | | |
Over the last two decades, new techniques have allowed decreased external fixator time by removing it once the distraction phase was completed and replacing it with internal fixation devices to allow the newly formed to consolidate. This development dramatically decreased the external fixation by at least two-thirds the expected time. The techniques included four novel methods:
- Lengthening over nail (LON) was introduced by Paley et al. in 1997. [10] An Intra-medullary nail is inserted concomitantly with the external fixator. At the end of the distraction phase, the nail is locked statically and the external fixator removed [Figure 11]
 | Figure 11 : Lengthening over nail (from Paley 1997) : Progress in and from Limb Lengthening) (a) Lengthening over a nail (LON). The nail is inserted and locked proximally, The external fixator is applied with its pins posterior to the nail, (b) After the completion of lengthening the nail is locked distally and the external fixator removed
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- Lengthening over plate (LOP). [11] There are two main advantages of this technique reported by Iobst in 2007: near elimination of the risk of infection that was associated with the technique of lengthening over nails; and its utility in children with open physis, where LON is contra-indicated [Figure 12]
- Lengthening and then nailing (LATN) was reported by Rozbruch et al. in 2008. [12] In this technique, an external fixator is used for gradual distraction. After the desired correction or lengthening is obtained, an intra-medullary nail is inserted and the external fixator is removed. There is still the risk of deep infection, however, this complication may be minimized by careful attention to details of the surgical technique, specifically avoidance of contact between internal fixation and external fixation pin tracks [Figure 13]
 | Figure 13 : Lengthening over plates (Oh 2009) The fixator is first applied on the medial side of the tibia, followed by the locking plate. No screws are inserted in the distal part of the plate. Following completion of distraction, the plate is locked distally and the fixator removed
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- Lengthening and then plating (LATP) was popularized by Harbacheuski et al.in 2012. [13] In both these techniques the most critical point is to keep the approach for subsequent plating or nailing free of contact with the external fixator to minimize or avoid the incidence of infection. The plate or nail is applied after distraction is completed and while the frame is still on in order to prevent any loss of position [Figure 14].
 | Figure 14 : lengthening and then plating ,showing external fixator configuration and lateral plate placement for proximal tibia lengthening (Harbacheuski 2012)
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All these techniques allowed gradual distraction with the help of an external fixator. Once the desired lengthening was obtained, the external fixator was removed and the position of the lengthened bone was maintained using either plate or nail that was applied during the initial surgery at the time of the osteotomy (LON, LOP) or after completion of the distraction phase (LATN, LATP). Although low, the risk of infection still remains a major concern.
| Fixator-assisted Internal Fixation of Deformities with Plates and Nails | | |
Gradual deformity correction with external fixators has many advantages. The most specific advantage is the potenial for adjusting the correction after the initial surgery and accurately analyzing post-operatively any residual deformity in the weight bearing status and correcting it. This is almost impossible if acute correction is contemplated, as no further correction is possible post-operatively. However, gradual correction with external fixators has numerous complications besides its numerous advantages. Could both techniques be "integrated" so as to benefit from the advantages of both? This led to the development of integrated techniques where the precision of deformity correction using temporary external fixators could be combined with all the advantages of acute correction. [14],[15] Thus, the use of external fixators as an immobilizing method to stabilize the osteotomy was eliminated. Both fixator-assisted plating [Figure 15] and fixator-assisted nailing [Figure 16] techniques have gained popular use worldwide. | Figure 15: Fixator assisted plating (modifies from the Baltimore Deformity course, 2016) (A) Femur showing distal valgus deformity, (B) Application of monolateral fixator to medial side of femur, (C) Osteotomy performed, (D) The necessary pre-planned deformity correction performed (first translation then angulation ) to restore normal mechanical alignement, (E) Once satisfactory correction obtained, the alignement is maintained with the fixator held in place, while the locking plate is applied to the lateral surface of the femur, (F) The external fixator is removed
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 | Figure 16 : Fixator assisted nailing (Kocaoglu 2011) (A) Application of the external fixator with Anterior placement of the Schanz screws to leave space for the intramedullary, (B) Anterior placement of the Schanz screws, (C) Osteotomy performed, (D) Interference screws are inserted prior reaming so that they guide the drill bit and then the intramedullary nail, (E) Drilling (AP view), (F) Drilling (lat. View), (G) Nail inserted, (H) Nail inserted and interference screws seen
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| Fixator-assisted Acute Correction of Deformities and then Lengthening Over Nails | | |
In cases presenting with both deformities and limb length discrepancy, by using this technique, the deformity can be acutely corrected with an external fixator and then an intramedullary rod can be inserted for lengthening over a nail. [16]
| Motorized Lengthening by Intramedullary Devices | | |
Motorized, elongating intra-medullary nails are the ideal lengthening devices: They completely obviate the need of external fixators [Figure 17]. They are able to eliminate all the problems associated with these devices: Pin track infections, pain, discomfort, and social problems. [17] Several lengthening intramedullary devices have been described in the last 20 years. Lengthening nails that rely on mechanical means to obtain distraction were the first ones to be described: the Albizia nail by Guichet in 2003; and the ISKD (Intramedullary Skeletal Kinetic Distractor (Orthofix, Verona) by Cole in 2001. In these devices distraction is initiated by rotation of the leg. However, the exact rate and rhythm of distraction has been shown to be inconsistent. This may lead to many problems (such as uncontrollable distraction, the runaway nail). Furthermore, the rotation maneuver of the leg could be painful and uncomfortable. These complications, led many surgeons to abandon these devices. The next type of intramedullary devices was the Fitbone nail developed by Baumgart in Germany in 1997. Distraction is initiated by electrical signals that activate an electric motor inside the nail. This nail has not been approved by the FDA, however published data has revealed excellent results in most cases. The third type of nail is the PRECICE nail introduced in 2011. Its big advantage over the Fitbone nail is the possibility for both lengthening and shortening. Distraction is initiated by remote control. In these last two nail innovations (and unlike ISKD) no painful rotational manipulation is performed. Initially these intramedullary devices were used for lengthening only; however when using this nail if the limb length discrepancy is associated with deformities, acute deformity correction can be performed followed by lengthening. This completely avoids external fixators for both deformity correction and lengthening devices. Both these nails are gaining popularity even though costs remain prohibitive in many countries. In addition, these internal lengthening devices are unable to address all the issues associated with limb deformities and limb discrepancy, but they could be an excellent addition to armamentarium for lengthening with or without simultaneous acute deformity correction. | Figure 17: Motorized intra-medullary nails (a) Fitbone, (b) PRECICE nail
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The evolution in deformity correction in the post-Ilizarov era follows two distinct trends: to try to avoid altogether or to decrease external fixation time as much as possible using external fixators; and to try to perform acute corrections if conditions allow. What seemed to be the gold standard in deformity correction few years ago - gradual correction with external fixators - is slowly changing to new approaches using various combinations of both external and internal fixation in order to minimize external fixation time. Although extremely attractive especially for patient comfort, these integrated approaches may be beyond the financial resources available in many countries. Still, the Ilizarov technique and fixators remain the gold standard for correction of deformities, specifically in the paediatric population worldwide.
| References | | |
| 1. | Ilizarov GA The tension-stress effect on the genesis and growth of tissues. Part I. The influence of stability of fixation and soft-tissue preservation. Clin Orthop Relat Res 1989;238:249-81.  |
| 2. | Ilizarov GA. The tension-stress effect on the genesis and growth of tissues: Part II. The influence of the rate and frequency of distraction. Clin Orthop Relat Res 1989;239:263-85. [ PUBMED] |
| 3. | Taylor JC. Correction of General Deformity with the Taylor Spatial Frame Fixator; 2002. Available from: http://www.jcharlestaylor.com. [Last accessed on 2016 Sep 04]. |
| 4. | Samchukov M, Birch J, Cherkashin A, Riccio A. Case 7. In: Rozbruch SR, Hamdy RC, editors. Limb Lengthening and Reconstruction Surgery Case Atlas. Heidelberg: Springer; 2015. |
| 5. | Shtarker H, Samchukov M. Case 5. In: Rozbruch SR, Hamdy RC, editors. Limb Lengthening and Reconstruction Surgery Case Atlas. Heidelberg: Springer; 2015. |
| 6. | Solomin LN, editor The Basic Principles of Skeletal Fixation Using the Ilizarov and Other Devices. 2 nd ed. Milan: Springer; 2012. |
| 7. | DeBastiani G, Apley AG, Goldberg A, editors. Orthofix External Fixation in Trauma and Orthopaedics. London: Springer; 2000. |
| 8. | Kocaoglu M, Tsuchiya H, Eralp L, editors. Advanced Techniques in Limb Reconstruction Surgery. Heidelberg: Springer; 2015. |
| 9. | McCarthy JJ, Ranade A, Davidson RS. Pediatric deformity correction using a multiaxial correction fixator. Clin Orthop Relat Res 2008;466:3011-7. [ PUBMED] |
| 10. | 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. [ PUBMED] |
| 11. | Oh CW, Kim JW, Baek SG, Kyung HS, Lee HJ. Limb lengthening with a submuscular locking plate based on an original article. J Bone Joint Surg Br 2009;91:1394-9. |
| 12. | Rozbruch SR, Kleinman D, Fragomen AT, Ilizarov S. Limb lengthening and then insertion of an intramedullary nail: A case-matched comparison. Clin Orthop Relat Res 2008;466:2923-32. [ PUBMED] |
| 13. | Harbacheuski R, Fragomen AT, Rozbruch SR. Does lengthening and then plating (LAP) shorten duration of external fixation? Clin Orthop Relat Res 2012;470:1771-81. [ PUBMED] |
| 14. | Kocaoglu M, Bilen FE. Fixator-assisted nailing for correction of long bone deformities. Oper Tech Orthop 2011;21:163-73. |
| 15. | Rozbruch SR. Fixator-assisted plating of limb deformities. Oper Tech Orthop 2011;21:174-9. |
| 16. | Paley D. Progress in and from limb lengthening. In: Johari A, Luk KD, Waddell JP, editors. Current Progress in Orthopaedics. Mumbai: Tree Life Media; 2014. |
| 17. | Rozbruch SR, Birch JG, Dahl MT, Herzenberg JE. Motorized intramedullary nail for management of limb-length discrepancy and deformity. J Am Acad Orthop Surg 2014;22:403-9. [ PUBMED] |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17]
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