|Year : 2004 | Volume
| Issue : 3 | Page : 191-198
|Principles and practice of deformity correction
Post Graduate Institute of Swasthiyog Pratishthan, Extension Area, Miraj, India
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Kulkarni G S. Principles and practice of deformity correction. Indian J Orthop 2004;38:191-8
I attribute this oration to Prof. Kini whose contribution to Indian Orthopaedics is phenomenal. I have chosen the subject of deformity of limbs which is relatively neglected and today deformity can be fully corrected, if exact principles are adhered to.
One of the greatest contributions of Ilizarov is corrections of deformity of limbs. Paley, Herzenburg, Catagni and others further developed the methods. Today deformity of limbs can be corrected to one degree or one mm geometrically. It is not necessary to use only Ilizarov ring fixator but one can correct a deformity by plating or intramedullary implant or monolateral external fixator such as orthofix, AO etc for getting good correction. One must understand the principles of deformity correction and rules of osteotomy.
Assessment of deformity: Thorough clinical examination is mandatory. One must find out the plane, magnitude, location, and level of the deformity. The patient is then subjected to standing X-ray with long film or stacked cassettes. It is very important that the patella should face forward when a deformity for correction in lower limb is evaluated.
Standard measurements: For pre-operative planning one must know the normal anatomical (A.A.) and mechanical (M.A.) axes and the angles [Figure - 1]. Lines of M.A. and A.A., joint lines, angles made by these lines are important to plan the correction of deformity. M.A. or weight bearing line passes through the center of the head of femur, knee and ankle. It makes an angle of 900 with the joint orientation line which passes through the center of head of femur to the tip of greater trochanter. This angle is called lateral proximal femoral angle (LPFA). Anatomical axis makes an angle of 6o or 7o with M.A., therefore, A.A. makes an angle of 840 with the joint orientation line. A.A. and M.A. do not meet at center of knee but proximal to the joint line. A.A. passes one cm medial to the center of knee. M.A. makes an angle of 870 with joint line and A.A. makes 810. For practical purposes, A.A. and M.A. of the tibia are the same and make an angle of 870 with tibial plateau line and 900 with the ankle joint orientation line.
Sagittal plane is more difficult. The tibial plateau line slopes posteriorly by 90 and the mid diaphyseal line makes an angle of 810 posteriorly with M.A. The lower end of tibia also slopes posteriorly 100, mid diaphyseal line makes an angle of 800 anteriorly with M.A. The two slopes are almost parallel. The mid diaphyseal line of tibia meets the plateau line and divides it into 1/5 anteriorly 4/5 posteriorly. Similarly middiaphyseal line of femur meets joint line, dividing it into 1/3 anteriorly and 2/3 posteriorly. This is because of the posterior bulge of femoral condyles. These lines, angles and starting points are all important. To calculate the plane of deformity, graphic method suggested by Ilizarov is very practical, especially in treating an oblique plane deformity [Figure - 2].
Malalignment and malorientation tests: Malalignment test determines the magnitude, level and site of deformity. It is done by plotting the M.A. line passing through the center of the head of femur, knee and ankle. Similarly the M.A. of tibia and joint orientation lines of knee and ankle are measured.
Alongwith an obvious deformity, there may be a hidden deformity, which can be detected by plotting the axes and joint lines. When the obvious CORA (center of rotation of angulation) does not coincide with true apex, there is another deformity at a different level (which may be the hidden deformity) or there is translational deformity. Hidden deformities can be detected by plotting the CORA or true apex and obvious or false apex. When CORA does not coincide with the obvious apex it indicates two deformities. The deformity is then managed by osteotomy with following options.
Option I – Two osteotomies at two CORAs
Option II – One osteotomy at resolution point.
If there are two CORAs, two osteotomies will correct both anatomic and mechanical axes [Figure - 3].
Rules of osteotomy
Rule 1: Osteotomy should pass through the bisector line. If the hinge is placed on the convex side, opening wedge osteotomy occurs. If on concave side, closing wedge, if at center, half closing and half opening (neutral wedge) is there. The line which bisects the obtuse angle is called a bisector line.
Rule 2: If the osteotomy is done at a different level than the CORA, then translation occurs. This is made use of in H.T.O. [Figure - 4]a
Rule 3: If osteotomy is done at a different level than CORA but hinge placed at osteotomy site, mechanical axis becomes parallel but anatomical axis becomes zigzag. This is used in certain situations [Figure - 4]b.
Rule 4: Where M.A. of proximal and distal segments meet, it is called as resolved CORA. If osteotomy is done at resolved CORA, the limb is functionally normal and avoids multiple osteotomies.
Rule 5: If the osteotomy is performed through the resolution point CORA rather than the true multiple apices, then the mechanical axis and joint orientation will be corrected with a residual alteration in the anatomic axis of the bone. This may be a cosmetic problem but it does not affect joint orientation or mechanical axis alignment.
Concept of mid segment: If the M.A. or A.A. of proximal and distal segment coincide and the middle segment may be of any length and any deformity, the limb is functionally normal provided the limb length is normal [Figure - 5]. If the mechanical axes of proximal and distal fragments are collinear, then the middle segment of any length and any deformity will not compromise normal function of the limb provided there is no limb length discrepancy.
Correction of bowing deformity: Bowing deformity has multiple apices. If there is more than one CORA, complete realignment of mechanical and anatomic axes requires more than one osteotomy for each CORA. The level of the CORA and the magnitude of correction are dependent on the middle axis line, which can be drawn at different orientations. Therefore, the level and magnitude of one apex determines the level and magnitude of the second apex [Figure - 6],[Figure - 7].
Principle of angulation translation
If the CORA is very near the joint, or in the joint, then translation of distal fragment is necessary. If open wedge osteotomy is done at the CORA, then M.A. is perfect. But it is difficult to fix the small fragment, osteotomy needs to be done at a distance from true CORA. Keep the hinges at the CORA and do osteotomy at the desired level-automatically translation and correction of deformity occurs. When the hinge is placed at the true CORA and osteotomy is done at a different level, the fragment which does not contain the hinge moves towards convexity.
Eversion and inversion of sub talar joint can compensate, to some extent, for varus and valgus deformities of ankle respectively, but supra-malleolar osteotomy is an excellent osteotomy to correct the deformities of ankle and foot, provided the relation of hind-foot to fore-foot is normal. It is simple, easy to do and rapidly healing as it is through cancellous bone. Principle of angulation translation is used.
Congenital pseudoarthrosis of tibia
For congenital pseudoarthrosis of tibia Ilizarov method appears to be superior to vascularised fibular graft. Resection of the lesion, bone transport and bone grafting are indicated in dysplastic type with tapering ends [Figure - 9]. For bone and periosteal grafting, a three inch incision is made on the iliac crest. Iliac growth cartilage is separated as a whole. Soft tissue is cut from the outer surface of periosteum, which is separated from bone sub periosteally. Bone graft of 2" by 1" size is obtained. A small 3 mm curette is inserted & cancellous bone is curetted. Enough quantity of graft is obtained. After resection and docking of the bony ends, bone graft is laid around the non union site, over which the periosteum is covered with smooth surface facing the graft.
In the cystic type with thick bone, compression with or without bone transport is necessary. Resection may not be needed.
Today there is no problem of union of pseudoarthrosis but refracture occurs in 30 to 50%. Refracture is due to - i) On going disease, and ii) Residual angular deformity. To prevent residual deformity, an intramedullary nail is passed through medial malleolus. Fibular pseudoarthrosis should also be treated similarly. The results of surgery before the age of 4 are poor. Our experience is of 33 cases of which 30 united while 11 had refracture.
Aseptic non-union: Most of the aseptic non unions can be treated by internal fixation.
Aseptic hypertrophic non union with deformity: Most of these can be treated by interlocking nail or a plate. However if there is lot of sclerosis, a nail can not be negotiated and if there is a large bump, plating is difficult. These are the indications for Ilizarov method [Figure - 10]. Another indication is hypertrophic non union with deformity which is treated by first correcting the deformity, then distraction 0.5 mm daily for 20 days, 20 days of no distraction, finally compression (accordion method).
I have classified the infected nonunion in 3 types
Type I: Mild infection- A bead of pus is seen on pressing, but no deformity. With debridement, antibiotic and two rings or functional cast or brace for 6 to 8 weeks, the fracture might unite.
Type II: Moderate infection but no deformity, no shortening, no gap.
Type III: Severe infection with deformity, gap or shortening. Treatment consists of through debridement, reaming intramedullary canal, vancomycin beads, corticotomy and Ilizarov fixator. Bone transport may be needed, if gap > 2 cms. Thorough debridement consists of removal of implants, infected soft tissues, sequestrii etc. Bony ends are excised till punctuate bleeding is seen. Then tourniquet is released and medullary canal is reamed. Antibiotic beads and /or a rod is inserted.
To make antibiotic beads 40 grams of bone cement powder (PMMA) is taken, 2 gms of antibiotic Vancomycin or Gentamycin ( in powder form ) or Tobramycin or any newer thermostable antibiotic is added to it. Now the liquid polymer is added to it. When it becomes a paste, it is wrapped around 6 mm or 7 mm Kuntschner nail of the required length, measured clinically or radiologically and smoothened by rolling between the 2 palms. The diameter of the composite nail should be uniform; it is passed through the hole of a nail gauge so that the proper diameter is achieved. For tibia we usually take 6 mm or 7 mm Knail, for femur 7 mm or 8 mm nail. While the cement is still soft, nail is bent as required, i. e. create Herzog's angle. The remaining cement is used to prepare chains of beads using a 14 gauge wire.
We have treated total number of 240 cases ; 220 united after multiple operations ; ten lost to follow up and eight did not united at all inspite of multiple operations. Amputation was carried out in two.
Chronic osteomyelitis with deformity
Chronic osteomyelitis, a common disease may present in many ways, as with deformity of the bone; non union of the pathological fracture with or without deformity; shortening with or without gap non union; associated joint stiffness or deformity.
All these problems can be solved in one stage by Ilizarov method. A thorough debridement and reaming of the medullary canal, if infected are mandatory. Dead bone and soft tissue are boldly excised. Even a large gap can be satisfactorily closed by bone transport and limb lengthening. Placement of vancomycin beads in the debrided area has given excellent results. Beads or antibiotic rod may be inserted in the medullary canal. "Infection burns in the fire of regenerate"—Ilizarov, is not true in all cases but only when the sequestrae are small or absent.
Hip reconstruction by pelvic support osteotomy
This is a good procedure for many hip diseases in our country, especially in the young.
- Advanced TB hip when both head and acetabulum are destroyed.
- Old septic arthritis
- Advanced O.A. hip due to AVN and other causes when total hip replacement (THR) is contraindicated or patient refuses THR because of socio-economic reasons.
Principle is to create an abduction deformity of the hip. An X-ray of pelvis with both hips is taken with the affected hip in maximum adduction. To maximum adduction 15 degrees is added. This will be the angle of abduction at the subtrochanteric osteotomy. Distal femoral osteotomy is also done to prevent valgus deformity of knee and to restore limb length.
THR is a good operation in the elderly but in the young it is associated with many complications and socio-economic problems. Our patients demand squatting and sitting crosslegged.
Ponseti technique of correcting club foot has given excellent results and is now followed in most of the centers across the world. This technique eliminates all the components of the congenital clubfoot deformity so that the patient has a functional, pain-free, normal-looking, plantigrade foot, with good mobility, without callosities, and requiring no modified shoes and avoiding major surgery which results in stiff painful foot though the patient has a plantigrade foot.
Ponseti manipulation and plaster cast is started on day 1, weekly change of cast for 6 weeks. If equinus is not corrected, percutaneous tenotomy is done under local anesthesia.
Technique: All the components of the clubfoot deformity have to be corrected simultaneously with the exception of the equinus which should be corrected last.
- The cavus, which results from a pronation of the forefoot is corrected as the foot is abducted by supinating the forefoot and thereby placing it in proper alignment with the hindfoot. Do not pronate forefoot.
- While the whole-foot is held in supination and in flexion, it can be gently and gradually abducted by applying counter-pressure with the thumb against the lateral aspect of the head of the talus.
- The heel varus and foot supination will correct when the entire foot is fully abducted in maximum external rotation under the talus. The foot should never be everted.
- Finally the equinus can be corrected by dorsiflexing the foot. The tendo Achilles may need to be subcutaneously sectioned to facilitate this correction.
Calcaneus should never be held while manipulating. The kite mistake was to hold the thumb at the calcaneo-cuboid joint. It took 40 years for the orthopaedic surgeons to move the thumb 1 cm superior to head to talus from calcaneocuboid joint.
We have treated 40 cases of CTEV by Ponseti technique, of these 2 needed soft tissue surgery and three needed tibialis anterior transfer to 3rd cuneiform.
Adult club foot
After the age of 12, we treat club-foot by triple osteotomy as in triple arthrodesis. Only subchondral bone is exposed. The talus, calcaneus, cuboid and navicular are compressed for 6 days then slowly distracted with Ilizarov to correct the deformity. Excellent regenerate is formed. Finally triple arthrodesis is achieved. We have done 8 cases, with satisfactory results.
Ilizarov is an excellent method of treating polio patients. All deformities and limb length discrepencies can be corrected at the same time in one stage. Minimal soft tissue release and distraction by external fixator give satisfactory results [Figure - 12]
Complications of Ilizarov method: All complications are preventable and treatable. Vascular injury is due to faulty insertion of wire or pins. I never had vascular complications. We had 3 cases of common peroneal nerve injury- all recovered. Main problem is the stiffness of joints especially flexion deformity of knee and equinus of foot while doing limb lengthening. Extensive physiotherapy from day one and counselling of patients and parents is important. Refractures and poor regenerate can be successfully treated by injection of bone marrow, bone graft or compression and distraction. Treatment of stiff joints by arthrodiatasis (Distraction arthroplasty) is very useful in the management of stiff joints. Other common complications are the pin tract infection and pain.
Fibular hemimelia: Three elements of fibular hemimelia need to be corrected.
1) Correction of foot deformities by postero lateral soft tissue release, which consists of excision of fibular anlage. This is postero lateral release as opposed to postero medial release in CTEV
2) Limb lengthening
3) Correction of bowing deformity of tibia.
All three may be done in one, 2 or 3 stages. Extra-articular soft tissue releases (tendo-achilles, peroneal tendons, interosseous membrane remenants, and fascial bands ) lead to some improvement in foot position. Supramalleolar osteotomy is done to correct valgus and procurvatum deformity.
The prognosis is good if there are more than 2 rays. If there is only one ray, amputation is a better option. Unsatisfactory results are due to recurrent residual deformity of the foot.
Proximal femoral focal deficiency
Proximal femoral focal deficiency (PFFD) includes a broad spectrum of defects ranging from minor hypoplasia of the femur to complete agenesis of the femur. Unstable hip joint, shortening, fibular hemimelia and agenesis of the cruciate ligaments of the knee and other anomalies may be associated with it.
Bilateral PFFD is best treated non-operatively. These patients can walk well without prostheses, but for social or cosmetic reasons extension prostheses may be provided. Patient learns to accept their short stature and is quite functional. Knee fusion is not indicated because the knee functions in conjunction with the hip pseudoarthrosis provides useful motion.
Stability of the hip and knee is important as a determining factor in the treatment. Establish continuity between the femoral head and the femur. This may be technically difficult. Surgery is best delayed till ossification of the femoral head and proximal metaphysis is adequate. Knee fusion is performed, creating a one-bone leg. Autogenous bone grafts should be added to the pseudarthrosis site. With advanced development of hip reconstruct many of these grotesque limbs can be salvaged [Figure - 13]. Subluxation and dislocation during femoral lengthening may occur especially with acetabular dysplasia.
Regardless of technique, limb lengthening in patients with PFFD is difficult with the ever present danger of knee and hip subluxation. If decided, should be done in 3 or 4 stages. Most children with PFFD can learn to walk without prosthesis, but prosthesis helps to equalize leg lengths.
Ankle and foot considerations 
In the sagittal plane, the articular surface of the talus is circular. The three-dimensional shape of this surface is a frustum ( section of a cone ). Therefore, the axis of ankle rotation is not parallel to the joint line. The axis normally runs from the tip of the medial maleolus to the tip of the lateral malleolus, passing through the lateral process of the talus. Clinically, it is best evaluated from behind.
Frontal plane ankle deformities
Varus and valgus deformities of the tibial plafond are normally compensated for by the subtalar joint. The normal subtalar range of motion is 300 inversion and 150 eversion. Therefore, the amount of ankle angulation that can be compensated by the hind-foot is 300 valgus and 150 varus when normal subtalar motion is present.
Varus deformity of the tibial plafond is tolerated less than is the valgus deformity because there is normally half the compensatory range of motion of subtalar eversion compared with inversion.
Varus deformity of the tibial plafond is unlikely to lead to degenerative changes. This is because the contact area of weight bearing between the tibia and talus is not decreased and may actually be increased because of increased load transfer from the medial facet of the talus to the very wide medial malleolus.
In contrast, valgus deformity of the tibial plafond may lead to degenerative changes of the ankle joint despite the foot's greater ability to compensate for valgus than for varus.
When correcting the severe deformities of the ankle joint, nerves are likely to be compressed. Therefore, tarsal tunnel decompression may be required.
Sagittal plane ankle deformities.
Plantar flexion and dorsiflexion of the ankle joint compensate for recurvatum and procurvatum deformities respectively, of the distal tibia. The ankle joint normally has 200 of dorsiflexion and 500 of plantar flexion range of motion. Therefore, the ankle joint can compensate for more recurvatum than procurvatum. For this reason, recurvatum of distal tibial deformity is better tolerated than is procurvatum deformity. Uncompensated procurvatum deformity presents as an equinus deformity. It is symptomatic because the foot is in equinus and also because of impingement of the anterior tibial lip on the neck of the talus.
The closer the CORA is to the ankle joint, the greater is the malorientation of the ankle joint (greater LDTA )
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G S Kulkarni
Post Graduate Institute of Swasthiyog Pratishthan, Extension Area, Miraj-416410
Source of Support: None, Conflict of Interest: None
[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]
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