Taylor spatial frame-software-controlled ﬁ xator for deformity correction-the early Indian experience

Complex deformity correction and fracture treatment with the Ilizarov method needs extensive preoperative analysis of modification of the apparatus for secondary or sequential in a series of 27 limbs in 22 patients. corrections can be time-consuming and fraught with error. and laborious postoperative ﬁxator alterations, which are error-prone. We report our initial experience in treating the ﬁrst 22 patients having fractures and complex deformities and shortening with software-controlled Taylor spatial frame (TSF) external ﬁ xator, for its ease of use and accuracy in achieving fracture reduction and complex deformity correction. Settings and Design: The struts of the TSF ﬁxator have multiplane hinges at both ends and the six struts allow correction in all six axes. Hence the same struts act to correct either angulation or translation or rotation. With a single construct assembled during surgery all the desired axis corrections can be performed without a change of the montage as is needed with the Ilizarov Materials and Methods: Twenty-seven limb segments were operated with the TSF ﬁxator. There were 23 tibiae, two femora, one knee joint and one ankle joint. Seven patients had comminuted fractures. Ten patients who had 13 deformed segments achieved full correction. Eight patients had lengthening in 10 tibiae. (Five of these also had simultaneous correction of deformities). One patient each had correction of knee and ankle deformities. Accurate reduction of fractures and correction of deformities and length could be achieved in all of our patients with minimum postoperative ﬁxator alterations as compared to the Ilizarov system. The X-ray visualization of the osteotomy or lengthening site due to the six crossing struts and added bulk of the ﬁxator rings which made positioning in bed and walking slightly more difﬁcult as compared to the Ilizarov ﬁ xator. Conclusions: The TSF external ﬁxator allows accurate fracture reduction and deformity correction without tedious analysis and postoperative frame alterations. The high cost of the ﬁxator is a deterrent. The need for an internet connection and special X-rays to operate the ﬁxator add to its complexity. ﬁ xator.

T he Ilizarov fixator is best known for limb lengthening Ilizarov fixator. 1 It is a software-driven hexapod fixator and deformity corrections. It has a well-defined role made with circular rings with six struts instead of the three for the treatment of complex nonunions with infection or four used with the Ilizarov. It is based on the science of and bone loss. It is also well established in the treatment of Projective Geometry and is the offshoot of the Chasles compound fractures.
Theorem. 2 It is based on a principle similar to that used in Aircraft Simulators. While application of the Ilizarov fixator itself is not difficult for simpler cases, the postoperative management in terms We hereby report our experience of "Taylor's Spatial Frame" fi xator.
The analysis of the oblique plane and combined angular and rotational deformities can pose significant challenges to surgeons who are less mathematically or mechanically inclined.

MATERIALS AND METHODS
Twenty-four patients were operated with the TSF fixator from Oct 2001 to June 2006, of whom 22 are included in the study. Their ages ranged from 13 years to 56 years. Twenty-seven limb segments were operated. There were 23 tibiae, two femora, one knee joint and one ankle joint [ Table 1].
Eight patients underwent lengthening with or without deformity correction in 10 tibiae. The length gained ranged from 2.5 cm to 6.5 cm. Three patients underwent only  lengthening in five tibiae. Of these three patients, one had Congenital Postero-Medial Bowing of the tibia and the other two had constitutional short stature. Two patients had growth arrest with shortening and deformities in two tibiae and underwent tibial lengthening and deformity correction. Three patients with posttraumatic tibial malunion underwent lengthening with deformity correction in three tibiae. All aforesaid tibial malunions were in varus, procurvatum and anterior translation deformities along with shortening of 2.8-4 cm.
Chaudhary M: Software-controlled Taylor spatial frame external fixator 1a-h] achieved full correction with the help of the TSF fixator. He had a malunion of the femur in childhood which was untreated and neglected and hence resulted in a compensatory deformity in the upper tibia. He had no shortening and hence underwent pure deformity correction with a gradual angulation-translation maneuver.
One patient suffering from postpolio residual paralysis had a 60 0 ankle joint equinus contracture. The equinus was not correctible on knee flexion. The TSF frame was used to ) .
Ten patients with 13 limb deformities (12 tibiae, one femur) underwent deformity correction with or without lengthening. There were seven tibial varus-procurvatum deformities, one tibial varus, one tibial varus-recurvatum deformity and three tibial valgus deformities, which underwent correction. Five patients were common to the lengthening as well as the deformity correction group. One patient with monomelic polytrauma had a fracture shaft femur and shaft tibia which were plated, but also had a dislocation of the knee which was neglected. It presented with varus, posterior translation and overriding 5 months after the trauma. The TSF fixator spanned the knee and was extended above into the femur and below into the tibia with Ilizarov rings to protect the plated shaft fractures which had not healed. The TSF fixator achieved gradual reduction of the neglected dislocation. Fixation to bone was achieved with wires in the fracture group and wire-half pin hybrid in the rest. These were

RESULTS
Special measurements which allow the software to get All patients achieved lengthening without any major oriented to the bone fragment position vis-à-vis the size complications. One tibia developed a 7 0 and orientation of the rings, are taken with the help of a procurvatum in the consolidation phase of lengthening translucent grid on the X-rays and fed into the software.
which could have been avoided had the patient agreed The ring and strut sizes are also fed in as are the desired to a pin-exchange. One patient with varus-procurvatum correction parameters. A note is taken of any structure at malunion with shortening could not achieve full length risk like the peroneal nerve in the region of neck of fibula, correction due to premature consolidation. The deformities so as not to stretch it. The software then outputs a program, were fully corrected but the length fell short by 12 mm. He which guides the surgeon and patient to turn the struts at refused a repeat corticotomy. specific intervals and amounts to achieve the desired result. Patients could follow instructions very easily as the struts The deformity correction patients achieved full correction were color-coded with tags.
of the deformities that ranged from 14 0 any residual deformity of more than 1 0 . In the illustrated Surgery was conducted under spinal or general anesthesia case [ Figure 1H], the apparent anterior translation of the depending on the patients' preference. All patients had full tibia is due to the deformity correction being done with segment X-rays before and during treatment. During the Rule 2 of deformity correction principles. 4 It means when postoperative phase, X-rays were made perfectly parallel the deformity is corrected by placing the hinges exactly to the reference ring, exactly orthogonal to the bone and at the "CORA" (centre of rotation of angulation), but the had to include the entire width of the ring to ensure that osteotomy itself is performed at a level different from the residual to 88 0 without the virtual centre of the ring could be calculated accurately for measuring the frame offsets.
Length measurements were made using magnification markers in the interim and with scanograms towards the beginning and end of treatment. The minor secondary g h deformities that arose during lengthening were also corrected. All the basic principles of frame application as for the Ilizarov fixator were applied to preserve joint range of motion. Most of the applications were in the tibia where the foot was not fixed and the ankle was kept free. Weight-bearing ambulation was ensured in every patient. true apex of the deformity, full correction of the overall axis will occur, albeit with translation at the osteotomy site. If noticed carefully, the mechanical axis of the limb is passing exactly through the centre of the knee. Rule 2 was employed and the osteotomy was performed distal to the level of the sub-articular deformity. There was not enough space for the upper tibial ring to have gone a little closer to the joint line due to the presence of the tilted lower femoral ring due to its severe deformity. Thus the osteotomy got shifted a little distally and necessitated a posterior translation of the distal fragment to achieve correction. Any more posterior translation of the distal tibial fragment would have caused a IJO -April -June 2007 / Volume 41 / Issue 2 lack of contact of the bony fragments. Hence it was decided to accept the small resultant anterior translation of the tibial mechanical axis as it did not exceed 12 mm. However, it may be clearly observed that the overall mechanical axis is completely corrected and passes exactly through the centre of the knee joint. This has been possible due to the small anterior translation of the distal femoral fragment. The femoral and tibial translations have the opposite effects on the position of the mechanical axis at the level of the knee joint.
Chaudhary M: Software-controlled Taylor spatial frame external fixator the abscissa gives the plane of the deformity.
Hinges are placed on a line which is Orthogonal to this diagonal as it meets the ring outline. The diagonal itself is extended in the concavity of the deformity to give the position of the motor rod. Then, a preconstruction of the frame is made based on this graphical analysis, usually with the patient examined under a C-Arm before surgery. This process can take several hours and can be very confusing to the surgeon All fractures united. Case no. 7 with Compound In the treatment of compound or comminuted fractures subtrochanteric femur fracture healed with 5° varus and 11° or lengthening, secondary deformities usually develop procurvatum. He also had a sciatic nerve palsy for which a during treatment. These need to be corrected by changing neurolysis was done. The nerve started recovery after 10 the Ilizarov frame montage. 5 This can be time-consuming weeks and recovered completely by six months. Case no. and requires a mechanical aptitude and is prone to error. 5 with a comminuted lower third tibia needed an iliac crest The most difficult of these constructs are the rotational and bone grafting and pin exchange to achieve union.
translation\ constructs, especially when combined with an angular deformity. With TSF fixator it was possible to fix the fracture in an emergency without worrying about the reduction. We could The TSF fixator has all the advantages of the Ilizarov fixator run the software program later to achieve a perfect reduction and overcomes some of its above mentioned difficulties. of the fracture fragments gradually and without pain.
The surgeon is greatly benefited by its ease of use 6 as well as the modern and high-tech interface. Other parameters Case 22 with knee joint dislocation underwent a relocation remaining the same, the TSF fixator makes preoperative and then was converted to a sound knee arthrodesis without planning and postoperative alterations of the fixator deformity. Case 21 with ankle joint equinus contracture was extremely simple. The software package takes away the corrected completely to an overcorrection of 5° and has tedium of extensive calculations needed for preoperative not recurred three years post frame removal. There were planning. It requires 13 simple measurements from standard no major pin track infections or severe limb pain during AP and lateral X-rays. The software does the calculations necessary to analyze the oblique plane or get the fracture to reduce accurately.

DISCUSSION
The six struts have multiplane hinges built in at both The Ilizarov fixator is accepted as the gold standard their ends which can serve any desired function: namely, for correction of complex deformities. A thorough lengthening, shortening, angular, translational or rotational understanding of the complex principles of deformity correction. Once the fixator is applied, all of these complex correction is necessary to analyze and accurately treat alterations can take place without any further labor and deformities. This would include some basic and applied changes to the fixator. This allows great ease of use for the trigonometry. The amount of time required to analyze a surgeon and ensures accurate reduction. complex oblique plane deformity, can be daunting to the treatment. casual surgeon.
The steps are: measure the deformity in the antero-posterior and lateral X-rays. With the graphical method of analysis on paper, an outline of the Ilizarov ring size to be used is drawn and the cross-section of the bone is drawn to simulate a transverse section of the limb at the site of the maximum deformity. The antero-posterior deformity is drawn as a line on the abscissa (X-axis) and the lateral plane deformity is drawn as a line on the ordinate (Y-axis). A rectangle is completed, the length of the diagonal of which gives the true magnitude of the deformity. The angle of inclination of this diagonal from There are a few disadvantages, however. The aluminum tabbed rings are bulkier (albeit lighter) than the Ilizarov ones. The six struts in a criss-crossing pattern frequently obliterate the view of the regenerate bone or fracture site. The decision to remove the fixator after judging for full consolidation or healing became somewhat difficult. We solved the problem by replacing the TSF fixator struts with those of the Ilizarov system to better visualize all sectors of the regenerate or the osteotomy site.
The computer software is only able to produce accurate results if the input is precise. There is a possibility that a m e d k n o w . c o m ) .