MANAGEMENT OF COMPLEX LOWER LIMB DEFORMITIES USING THE TAYLOR SPATIAL FRAME

Gamal Ahmed Hosny 1 ,Khaled Mohamed Hassan 2 , Mahmoud Mohamed Ibrahem Matter 3 , Ahmed Mohamed Ahmed Nahla 4 and Osam Mohamed Metwally Hassan 5 . Orthopaedic Surgery Department in Zagazig University and Banha University. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


Patient and Methods:-
This study was carried out in Orthopedic Surgery Department, Faculty of Medicine, Zagazig University hospitals in the period between June 2014 and may 2017, a prospective study was conducted involving 21 patients with 28complex metaphyseal and diaphyseal tibial and femoral deformities around the knee joint that were managed by the Taylor spatial frame in conjunction with bone osteotomy.
There were 18 males and 3 females; their ages were ranged between 14 and 40 years. The mean age was 18.2 years The deformities were located at the proximal metaphysis in 23 tibias , and in 5 femurs at the distal metaphysis The mean hospital stay was 3.5 days (Range 3-5 days). A fibular osteotomy was performed in all tibial cases. Patients were corrected on average0.75 mm (Range0.5-1mm).
Varus deformities constitute the main deformity in this study as it were presented in 23 limb segments "22 tibias and 1 femoral cases (78.58%), valgus deformities were presented in 5 limb segments "1 tibial and 4 femoral cases" (21.42%) Operative Technique:-Mechanical axis deviation is determined with use of the malalignment test as described by Paley. The lateral distal femoral angle, medial proximal tibial angle, and posterior proximal tibial angle are measured to analyze deformities around the knee.
The Center of Rotation of Angulation CORA is identified by locating the intersection of the proximal and distal mechanical axes. Often this point is chosen to be the origin as well. (In TSF terminology, the origin) An osteotomy site is selected, typically at the apex of the deformity. If the bone is very sclerotic at the apex, then an adjacent alternative site is used to maximize bone-healing potential. When making an osteotomy at a site other than the center of rotation of angulation, one must translate the bone to reestablish alignment.
These values are entered into the computer as deformity parameters to ensure that the distal fragment will be well aligned at the completion of the adjustment period.

Discussion:-
The main problem in the correction of complex deformities with classic circular external fixators is the modifications needed in the fixator for residual deformities that occur. On the other hand, the Taylor spatial frame can provide perfect anatomical reduction and stability with the help of the computer software in complicated deformities. The important advantages of TSF are being a very stable external fixator, correcting all components of the deformity.
Hosny used the TSF in 22 patients for the correction of lower-limb deformities including lengthening in three patients with congenitally short femurs, and deformity correction and lengthening in one with a posttraumatic femoral fracture. Although the findings from this small subgroup of patients could not be isolated, the overall results were 18 excellent, two good, and two fair. In another study, 13 of 44 TSFs were applied to the femurs of pediatric patients to address angular deformities and limb length inequalities Eidelman et al. reviewed their experience on the use of TSF in both tibia and femur. Complications included pin tract infections in two, fracture of the regenerated femur after frame removal in two, femoral fracture after a fall in one, delayed union in one, and residual femoral deformity in a patient with skeletal dysplasia. After experiencing three fractures, the authors suggested that removing the frame relying on radiographic evidence is inadequate for determining the extent of bone healing, and advocated dynamizing the frame to prevent fractures. One way of dynamizing a Taylor spatial frame is to replace the TSF struts with Ilizarov rods and loosen them to have dynamization. Another option could be to remove one of the struts, and allow the patient full weight-bearing on the frame. Since this will break the hexagonal construct and make the whole frame unstable, removing one or more struts of the TSF is subject to fractures if the bone is not healed enough. It does not act as the dynamization in Ilizarov devices or the monolateral external fixators which brace the regenerate while allowing the patient to fully weight bear. In our series we did not have any fractures related to early frame removal or dynamization.
Metin KUCUKKAYA, et.al. studied correction of complex lower extremity deformities with the use of the Ilizarov-Taylor spatial frame, The mean duration of external fixator was 24.5 weeks (range 18 to 37 weeks) in 13 1209 tibial and five femoral segments. In all cases, correction was applied until the mechanical axis reached normal limits. Complete consolidation was achieved in all osteotomized bone segments.
Haridimos Tsibidakis, evaluates the use of the Taylor Spatial Frame (TSF) for the correction of acquired and congenital tibial deformities in children. 86 tibia deformities were corrected in 66 children during a period of 7 years and were classified according to anatomical and dominant type of deformity. Follow up was 54.2 months. Gradual correction was performed according to the individualized time schedule. Significant correlation was found between patient's age and number of difficulties.
Keshet D, Eidelman M studied clinical utility of the Taylor spatial frame for limb deformities, and conclouded that standard TSF with 6 oblique struts fixed on to bone model can provide comparable stiffness on axial loading and better stiffness on torsional loading to conventional Illizarov external fixator " IEF " with 4 threaded rods. The mechanical properties are theoretically favorable for both fracture healing and new bone formation. Changing to stronger hollow connecting bars or increasing the number of threaded rods did not significantly increase the stability against torsional forces. That findings suggest that TSF may provide a better alternative to conventional IEF as far as mechanical property is concerned.
In general, despite many challenging cases, our results are comparable to the good results achieved by other published series of TSF treatments.
Obvious disadvantages of TSF are a deficit of small rings and struts for the correction of deformities in small children, which is otherwise difficult or impossible. Another problem is the high cost of TSF equipment.
Nevertheless, in our opinion, TSF is the most accurate and stable fixator available today, with a relatively short learning curve.
Instability because of using only two rings and few pins was never seen in our patients. TSF gives excellent stability. Based on our results, we think that the TSF allows safe gradual correction and is accurate and well tolerated. Our results compare favorably with the published literature.
The results overall were good.
We now use the TSF as the first line of treatment of complex lower limb deformities.

Conclusion:-
We believe that the TSF is an excellent tool for the correction of multiple plane deformity around the knee joint in children and adolescents and significantly expands our ability to correct precisely the most difficult deformities.