Ilizarov ring fixator

ILIZAROV RING FIXATOR: Basic concepts, components, application, uses, challenges

1. ILIZAROV RING FIXATOR: BASICS DR. D. P. SWAMI AIIMS DPS

2. Outline History Principles Application of circular fixator Basic principles of operative techniques Stages of Ilizarov treatment technique Post operative management Dynamization and removal Safe zones in tibia Indication Complication Advantage Disadvantage Recent advances in Ilizarov Different applications of Ilizarov DPS

3. History Born in Soviet U nion. In 1950, sent to Kurgan, Siberia to look after injured Russian soldier. Inspiration- by shaft of bow harness on horse carriage. Using spokes of bicycle from local bicycle shop, he devised ring external fixator. Accidently he found new bone formation radiologically in a patient who turned compressing rods between rings in distraction rather than compression. He revolutionized the treatment of difficult musculoskeletal problems. Professor Gavril Abramovich Ilizarov (1921-1992) “THE MAGICIAN OF KURGAN ’’ DPS

4. RUSSIAN ILIZAROV SCIENTIFIC CENTRE OF RESTORATIVE TRAUMATOLOGY AND ORTHOPEDIC ,KURGAN ,RUSSIA DPS

5. Principle of Ilizarov Based on the principle ‘ ’that growing bone changes its form and volume according to external stimuli ’’ ( Wolff’s law ), Ilizarov subjected bone to continual external tension in any direction, which can lengthen the bone or correct deformities. Distraction osteohistiogenesis Mechanical induction of new bone formation Neovascularisation Stimuli of biosynthetic activity Activation and recruitment of osteoprogenitor cells Intramembranous ossification DPS

6. C o n t … His biological principles can be summarized as follow- Minimal disturbance of bone and soft tissues Delay before distraction Rate and rhythm of distraction Site of lengthening Stable fixator of external fixator Fun ctional us e o f limb a n d intense physiotherapy DPS

7. Distraction osteogenesis Defined as biologic process of new bone formation between surfaces of 2 segments of bone that are gradually separated by incremental traction. Bone f orm a tion f o ll o w s v e c t o r of distraction. Bone is separated by corticotomy. Di s t r a ction is don e @ 1 m m/d a y in f our interval i.e. 0.25mm four times per day. When d e si r ed len g th is achi e v ed consolidation phase follows. DPS

8. Instrumentation Primary components- elements used to correct skeletal deformities. E g - rin g , wi r e, wi r e fi x a tion bolt and buckles, pin and pin clamps. S e c onda r y c omp o ne n t- element necessary for assembly of frame. Eg- rods, plates, support, post, hinge, washer , sockets, bushing, bolts and nuts. DPS

9. R i n g s Principle component All rings are placed perpendicular to long axis of bone. Made up of stainless steel or carbon fiber to bear high stress (up to 150 kg) Internal diameter measures from 80- 240 mm. Function- S uppo r t t r ans f i x a t i o n o f i li z a r o v , o li v e wires and half pins Builds a fixator frame connecting two or more rings. Props up frame’s supplementary parts DPS

10. R i n g s Holes in the ring used for introduction of threaded rod, a hinge or connector plate. Two half ring can be connected to form full ring or oval ring. Five-eight ring facilitate joint motion and is commonly deployed near knee and elbow joint. It also facilitate introduction of cross wires, distinct advantage near these joint. Omega rings is modified five-eight ring fits deltoid area of shoulder. Five-eight ring and omega ring are weak so needed 3 point fixation to a full ring. DPS

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12. A r c h e s La rg er diam e t er t han half rings. Extra holes for use at the level of proximal femur or humerus. Does not limit joint motion . DPS

13. Ilizarov wires Stainless steel of critical hardness and elasticity. Types- beaded and non- beaded. With trocar point- better directional hold when drilling cancellous bone such as metaphysis and epiphysis. With bayonet point- better directional hold when drilling cortical bone such as diaphysis. DPS

14. Olive wires Metallic bead in wire. Function - I n t erf r agme n t a r y compression Increasing stability of the construct Gradual distraction Translation of fragment DPS

15. B o l t s Hexagonal head of 10mm Threaded shaft of 6mm diameter Pitch of thread is 1 mm Length of 10, 16, and 30 mm used. H a v e longitudin a l hole s o r sl o t ju s t below head to fix wires to the ring or other components of the frame. It is use to connect the threaded socket and bushing through the rings, for connecting plate, for fastening rods and half pins through socket aperture. DPS

16. B o l t s To achieve stability wire must be tensioned, by turning 2 wrenches simultaneously tension is applied on wire as it wrap around the bolt. To obtain optimal stability each wire should be place on top and bottom of each ring. Coupled effect avoids torque of each bone segment fixed to the ring. Fixing the wire on the both surface also prevent wrapping of the ring. DPS

17. N u t s Diameter- 6 mm Height- 6, 5 and 3 mm Pitch of thread- 1mm S o 1/4 th t ur n f ou r tim e s pe r da y is recommended distraction compression rate. Turn of nut is used as driving force in Ilizarov system. Function- Tighten the connecting bolt Stabilizes connecting rods Drivin g v e c t o r f o r di s t r a ct i o n- c omp r ession movement Lock socket and bushing onto threaded rod Secure hinge clearance and gap on threaded rod Affix pulling wire of distraction device. DPS

18. Buckle Combine a plate with 2 fixed threaded rod with two hole plate held together with 2 nuts. A lon g itud i na l g r o o v e hol d a wire to ring like a slotted bolt. Allow mechanical derotation or angular correction. DPS

19. R o d s 6 m m thi c k s t ainless st eel r od is main connector. 4 rods at equidistant are used to connect 2 neighboring rings. By turning nuts we can fix rods to the frame. W e c an p r o du c e desi r ed c omp r es s ion or distraction needed. Rods are machined so that thread causes 1mm translational along its longitudinal axis with each complete 360* revolution of nut. Slotted cannulated rod with 2*2 mm slot and length of 20 thread, act as pulling device. DPS

20. P l a t e s Use to reinforce ring fixator. Short plates used as extension of rings. Long plates used to reinforce large frames during bone fragment transport. Plates with threaded rod use to support a hinge as well as a frame. Twisted plates used to connect two components positioned at right angle to one another. Curved plates used to increase circumference of half ring and connect two half ring. DPS

21. Telescopic rod Hollow rods used as support and connecting elements of the rings. Base is m achined t o acce p t 10 mm open end wrench. Head have 2 holes- 1st for threaded rod. 2 nd for bolt to lock rods. P r o vi d e st abili t y wh e n long distance spanning is required between rings. Now hollow tube may contain slo t t e d w i nd o w with g r adu a t e d metric marking on one side. DPS

22. Support post Type- male and female post. Male post- threaded projection fixed with nut. F emale p o s t - fixed with bolt. Function - th r eaded h o le Third wire can be connected to post. Can also work as hinge. Can be connected to other part of apparatus to provide additional stability. Wire can be tensioned DPS

23. Hinge post Have supporting base with two flat surface matching the standard 10 mm wrench Important function is correction of angulation. Type – male and female hinge post DPS

24. Threaded socket & bushing Threaded rod interconnect threaded rods. It stabilize two rings together. Hol e on si d e, c a n b e u sed f or threaded rod in horizontal direction. Bushing is 12 mm long spacer with smooth longitudinal hole that provide free motion of threaded rod length wise. DPS

25. W a s h e r W asher fixation use to raise a bol t t o the wi r e wi r e th a t does not sit directly on ring. Types - c oni c al Slotted s i mpl e , sl o t t ed and w asher all o w wi r e fixation on one side in special circumstances. Conical washer act as swivel for connecting rings or plates which are not parallel. DPS

26. Tensioners Used to tension wire to an exact force, thus improvising stability for entire bone frame construct. wi r e T yp e s - d y na m ome t ric and s t anda r d tensioner. Wire should be tensioned from 50-130 kg. Amount of tensioning depends upon- Weight of patient Local bone quality Treatment plan Local frame construct S t anda r d wi r e t ensi o ne r no t c alib r at ed a nd cumbersome to use. DPS

27. D y n a m o m e t e r Parts of dynamometer- Handle for applying pressure Dynamometer scale Fixed jaw Mobile jaw Using of dynamometer- Rotate handle anti clockwise until wire get inside Engage the fix jaw to the ring R o tat e handl e clockw i s e u n til des i r ed tension is achived. Tighten the nut at desired tension. Rotate handle anti clockwise to loosen the wire. DPS

28. Assembly of circular fixator Major considerations- Stability of fixation of the frame to the bone. The prevention of gross bone fragment motion. A b i l ity t o man i p u l a t e bon e and t o p e r f or m ne cessa r y f r a gme n t m o v e m e n t suc h as o f these s t r a ig h t enin g , ben d i n g , di s t r ac t ion, c o mp r es s i on , r o ta tion and c omb i n a tion movement. Construction of frame can be done in advance or during surgery. Important aspect of frame assembly- Ring positioning Ring inclination Ring orientation Ring level Spacing between skin and ring DPS

29. Ring positioning Rings are main component Types- Main proximal frame supporting ring- it bears weight of entire construction. Located 3-5 cm away from joint. Stabilizing frame supporting ring- may be stationary or moveable. Located 3-5 cm away from joint. Pushing pulling ring- moveable ring used for compression or distraction. Located 3-5 cm distal to fracture- osteotomy-nonunion site. Reference ring- used as reference for supporting rings or distraction-compression rings. It corresponds to apex of bone angulation. Connecting rings- used for application of special forces in transverse or oblique direction for correcting deformities. DPS

30. Ring inclination Ring i s p o s i t i o ned a r ou n d t he anatomic bony center of fixation. Inclination of ring is perpendicular to bone segment fragment. Minor inclination could produce large derangement at the distal end. DPS

31. Ring orientation Rings at different level and in different inclination are oriented so that the connections of half rings must aligned on same straight line. After correction rings arrive in parallel position to each other and bone fragments in good alignment, however half rings connections are rotated location. DPS

32. Spacing between skin and ring A t the nar r o w e s t g ap spac e o f at least 3cm should be maintained between inner curve of ring and skin. Achieved in 3 ways- Limb measured in 2 plane and largest diameter is considered. Add 6cm to this diameter which provide you size of ring. Attach most anticipated size and seek a space of 3cm. Use plastic template. DPS

33. Basic principles of operative technique Exit and entrance sites must be pre determined. It must be located 1.5- 2 cm from neurovascular bundle. Wire must be introduced slowly and on the side containing critical structure. Skin must be supported by finger pressure to secure exact point of wire penetration. In planned distraction skin should be pushed towards site of corticotomy. DPS

34. Loosely attached slotted fixation bolt at entrance site guide K-wire and prevent deflection during introduction and drilling. One wire one hole to prevent incorrect positioning. Pu s h wi r e manually t o bon e b e f o r e drilling. DPS

35. Prior to passing wire each muscle should be stretched maximally to its functional length to prevent contracture. DPS

36. Wire is drilled through both the cortex, passing through bony canal and bone marrow transmedullary. DPS

37. For stability 2 wire criss crossing at an angle as close to 90* are required. (if angle ⩽ 30*- chance of side to side ring displacement; If angle 30-45*- chance of ring sheering movement.) DPS

38. Ring should be well stabilized to bone for that wire should not be brought down to the ring, ring should be brought upto the wire using washer, support, post or hinges. When greater load is required, 3 wire can be transfixed to one ring. DPS

39. When wire is close to ring connector, it bear small axial load and when it is away from ring connector it bears greater axial load, developing larger diameter hole in bone. DPS

40. Stabilize ring through wire with stoppers and offsite wire, which is fasten to ring by support DPS

41. Adequate tension is paramount importance . Inadequate tensioning adversely effect development. Range of wire tensioning- 50- 130kg. Tensioning strength of wire on half ring- 50-70 kg. Tensioning strength of offsite wire- 50-80 kg. T ensioning s t r en g th of s i ng l e wi r e o n rin g - 100kg. T ensi o nin g s t r en g th o f 2 - 3 wi r es o n r ing in young patient – 110 kg each ring. T ensi o nin g s t r en g th o f 2 - 3 wi r es o n r ing in adult patient – 120-130 kg each ring Tensioning strength of wire with olive stopper- 100-110 kg. DPS

42. Position of wire in relation to hole and type of fixation part appropriate to each situation. DPS

43. Technique of wire bending- bending wire around outer wall of ring prevent scratch or puncture of physician or patient skin. DPS

44. Corticotomy It is low energy osteotomy of cortex preserving local blood supply to both periosteum and medullary canal. Types- monofocal & bifocal Ideal corticotomy- Long oblique Metaphyseal in situation No comminution N o disru p tion o f endo s t e a l & periosteal blood supply Fi x ed in a n at omi c a l p o siti o n with gap <2mm DPS

45. Stages of Ilizarov treatment technique Fixator application and following latency period of 4-7 days. Period of distraction/compression (1-4 months depending on case). P er i o d of i m m o b i l i t y a n d fi x a tion of b o n e po sit i o n ( u s ual l y t wice period of distraction /compression). Discontinuation of distraction-compression and frame dynamization 15 to 20 days prior to fixator removal. Period of immobilization with a cast or brace. DPS

46. Immediate (1 st and 2 nd day)- Limb elevation, protection of wire ski n i n t er f ac e , non bandage for incision, ci r cul a r sterile dressing. 1 st week (after 2 days)- Sterile dressing, active and passive immobilization, partial weight bearing, physiotherapy. After 1 week till removal- Check for wire tension, look for wire site infection, nuts and clamp tightness, dynamization Post operative management DPS

47. Dynamization of apparatus When dynamization is done? Satisfactory appearance of regenerate calcification, complete recanalization and formation of cortex is seen. What to do for dynamization? Loosen the nuts at sides of connecting rod. Purpose of dynamization? Allow static fixator to distribute weight across fracture site, as a result elasticity of callous decreases, bone stiffens and strength increases. Thus axial dynamization helps to restore cortical contact and produce stable fracture wi t h inhe r e n t mechanical pattern supp o r t . DPS

48. Removal of apparatus A month too late is better than a day too early . X-ray must show at least 3 cortices ossified out of four. B e f o r e r em o ving f r am e , p a tie n t m a y b e a s k ed t o us e limb in a functional manner. Before cutting wires, tension of wires must be removed. DPS

49. Safe zones in tibia The diagram demonstrates the wide medial and lateral access to the tibia that is available for pin insertion. Zone 1- 13-15 mm distal to the articular surface Zone 2- 7-8 cm distal to the knee joint Zone 3- 12 cm distal to the knee joint Z on e 4 - Ju s t i n f e r ior t o the m i dpoi n t between the knee and ankle joints Zone 5- 12 cm from the ankle joint Zone 6- 2 cm proximal to ankle joint DPS

50. Zone 1 First reference wire inserted for fine wire fixation i.e. in the transcondylar transverse plane anterior to the fibula (13-15 mm distal to the articular surface). Optimum fixation is then obtained using two half pins placed anteriorly. The medial one can be used to also fix the fibula head. Alternatively a 2-3mm smooth pin can be used to transfix the proximal tibio-fibular joint, for example in tibial lengthening. This is inserted by palpating and protecting the common peroneal nerve with the thumb and holding the soft tissues posteriorly, while the knee is flexed and the pin is driven through the fibular head. The pin is directed anteriorly, medially and slightly distally toward the closest available ring. DPS

51. Zone 2 Th e half perpendicular pi n is inser t ed t o the subcutaneous border of the tibia on the medial aspect. The fine wire is inserted slightly obliquely to the transverse plane of the tibia to engage it in its widest portion. DPS

52. Zone 3 Tibia l fi x a tion medial-oblique is with a wi r e a n d a half pin inserted into the medial aspect of the tibia perpendicular to the medial aspect. DPS

53. Zone 4 The insertion of the wire and half pin at this level is similar to that described for Cut Two and Three. DPS

54. Zone 5 The wire at this level is placed almost parallel to the frontal plane of the tibia. The half pin is inserted again on the medial aspect, slightly obliquely to the wire as shown in the diagram. DPS

55. Zone 6 A distal tibial reference wire is the initial fixation used, with a direct medial to lateral wire. The fibular stabilization takes place through a lateral oblique wire directed from posterolateral to anteromedial. Additional stabilisation can be achieved with a wire directed form anterolateral to posteromedial, anterior to the neurovascular bundle. Alternatively a stabilizing half pin can be inserted anteriorly, lateral to the tibialis anterior tendon. This should be done with care using a limited open technique through a small incision, which is dilated with an artery forceps. The forceps is used to displace the soft tissues and therefore protect the anterior neurovascular bundle, allowing safe pre-drilling and insertion of a 5 or 6mm half pin. DPS

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59. Indication Fracture nonunion Limb lengthening procedures Long bone deformity correction Open fractures Malunion Correction of joint contractures Correction of congenital deformity (hemimelia, club foot, cl u b hand , c on g eni t al pseudoarthrosis) Reconstruction of bone defect Vascular insufficiency (TOA, Berger’s disease) DPS

60. C o m p l i c a t i o n Late complication- Pin site infection Pain at corticotomy site and during lengthening Soft tissue contractures and joint stiffness Osteoporosis Reflex sympathetic dystrophy Progression of angular deformity or creation of new one after fixator removal. Limb swelling N o nunio n o r p r em a tu r e lengthening site Compartment syndrome Joint subluxation Early complication- Vascular complications Neurological complications Comminuted fracture of osteotomized bone Local skin tightness Psychologic incompatibility c on s olid a tion at DPS

61. Advantage Minimally invasive Relatively easy application Allows deformity to be corrected in 3 dimensions (axial, angular & translational) Patient is mobile through out course of treatment Early physiotherapy prevents joint stiffness and contractures. Bone grafting in unnecessary Simple hard ware removal DPS

62. D i s a d v a n t a g e Mechanical Distraction of fracture site Pin bone interface failure Bulky frame Refracture Longer duration of surgery Instability of apparatus Breaking or loosening of wires Long learning curve Biological Pin tract infection Neurovascular injury Tethering of muscle Soft tissue contracture Pain Oedema Joint stiffness O s t eol y s i s a r ou n d wi r es DPS

63. Recent advances Taylor spatial frame 2 c arbon r ings c onnec t ed b y 6 telescopic linkage rods called strut. Stru t h a v e virtual hin g e joi n t at both the ends. C an b e applied with il i z a r o v and other fixator system. It provide universal and 3 dimensional bone movement, so that path of reduction or correction can easily be modified. DPS

64. Recent advances Hybrid fixator- Proximal ring connected to 2 or 3 pins distally with connecting rods. Mostly for proximal tibia fracture DPS

65. Combined compression-distraction technique DPS

66. Bone transport technique DPS

67. Ilizarov to prevent contracture DPS

68. Correction of ankle joint fused in equinus position DPS

69. Correction of club hand DPS

70. Non union DPS

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72. Deformity correction DPS

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74. Treating neglected club foot with Ilizarov DPS

75. Treatment of open fracture and bone loss DPS

76. Difficult fractures DPS

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80. Congenital pseudoarthrosis DPS

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82. Limb lengthening DPS

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84. Infected nonunion DPS