|Year : 2016 | Volume
| Issue : 2 | Page : 108-112
Plating following gradual realignment with the Taylor spatial frame for refractory congenital pseudarthrosis of the tibia: A novel technique
Issei Nomura, Koji Watanabe, Hidenori Matsubara, Toshiharu Shirai, Hiroyuki Tsuchiya
Department of Orthopaedic Surgery, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
|Date of Submission||11-May-2016|
|Date of Acceptance||25-Aug-2016|
|Date of Web Publication||16-Sep-2016|
Department of Orthopaedic Surgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara machi, Kanazawa, 920 8641
Source of Support: None, Conflict of Interest: None
Congenital pseudoarthrosis of the tibia (CPT) is an intractable pediatric orthopedic disease. This study aims to report short-term outcomes of our staged surgery: Gradual realignment with Taylor Spatial Frame (TSF) and conversion to a locking plate for Boyd classification type II CPT. Three males (mean age, 10.3 years) who had undergone past surgeries (average, 3.7) were included. The pseudoarthrosis was atrophic and mobile in all cases. The distal bone fragment was translocated to the proximal anterior direction, resulting in shortening of the leg. In the first surgery, TSF was applied spanning the pseudoarthrosis. A foot ring was placed on the foot, and the distal fragment of the tibia was fixed together with the foot. The deformity correction was initiated a day after surgery. TSF was converted to a locking plate after scheduled alignment was achieved, and cancellous bone of iliac crest was grafted. Bony union was achieved at a mean of 3 months, and patients walked independently after mean 56-month follow-up, without any complications. Although the treatment outcome after the vascularized fibular graft and the Ilizarov method is relatively successful, several issues require long-term relief, and the surgical procedure requires specialized techniques. The present method shortens the duration of external fixation, uses only simple surgical maneuvers, and prevents re-fracture by anatomical alignment and indwelling of the plate.
Keywords: Congenital pseudarthrosis of the tibia, external fixator, plate conversion
|How to cite this article:|
Nomura I, Watanabe K, Matsubara H, Shirai T, Tsuchiya H. Plating following gradual realignment with the Taylor spatial frame for refractory congenital pseudarthrosis of the tibia: A novel technique. J Limb Lengthen Reconstr 2016;2:108-12
|How to cite this URL:|
Nomura I, Watanabe K, Matsubara H, Shirai T, Tsuchiya H. Plating following gradual realignment with the Taylor spatial frame for refractory congenital pseudarthrosis of the tibia: A novel technique. J Limb Lengthen Reconstr [serial online] 2016 [cited 2019 Jun 18];2:108-12. Available from: http://www.jlimblengthrecon.org/text.asp?2016/2/2/108/190718
| Introduction|| |
Congenital pseudoarthrosis of the tibia (CPT) is an intractable pediatric orthopedic disease that is extremely difficult to treat. It is characterized by patients that have experienced past surgery/surgeries, and there is atrophic pseudarthrosis with atypical mobility. Although the bone union rate after a vascularized fibular graft surgery is 60%-88%, , it requires long-term relief from weight bearing, and the surgery requires specialized techniques. Dobbs et al.  reported that although the bone union rate achieved using intramedullary rods is 86%, the refracture rate is as high as 57%, and the time required for bone union is as long as 16 months on average. Another issue is that insertion of an intramedullary rod may cause contracture or ankylosis of the ankle and the subtalar joint. The bone union rate of the Ilizarov technique is 75%,  which allows precise realignment. However, the refracture rate is as high as 31%, which is similar to other surgeries.  Combined treatment with the Ilizarov technique and intramedullary rods and periosteal and bone implants result in 100% bone union and a 40% refracture rate.  Either procedure can achieve bone union, but outcomes are unsatisfactory, particularly with regard to difficulties of preventing a refracture. A report by the European Pediatric Orthopaedic Society, which investigated the functional prognosis of CPT, revealed that 10% patients have an amputation, and ≥60% were incapable of performing sports activities. , We performed a staged surgery to achieve precise realignment, decrease the duration of external fixator use, and prevent a refracture in Boyd Type II CPT. The gradual realignment with the Taylor Spatial Frame (TSF, Smith and Nephew, Andover, MA, USA) was converted to a locking plate (here referred as the converting surgery) and achieved good results. Therapeutic outcomes are reported here.
| Patients and Methods|| |
Patients were 3 male (mean age, 10.3 years; 2 cases of Type I neurofibromatosis and a case of osteofibrous dysplasia), who had undergone past surgeries (average, 3.7). In all cases, the pseudoarthrosis was atrophic and mobile, and the distal bone fragment was translocated in the proximal anterior direction, resulting in shortening of the leg.
- The course of the realignment was simulated before the surgery to achieve anatomical alignment with minimal leg shortening. Templating of the plate was performed to confirm that plating was possible [Figure 1]
|Figure 1: (a) The realignment course is simulated before the surgery, (b) templating of the plate is performed to confirm that plating is possible|
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- TSF was applied to span the pseudoarthrosis in the first surgery [Figure 2]a. A full ring was placed on the tibial shaft. A foot ring was placed on the foot, and the distal fragment of the tibia was fixed together with the foot. Wires on the distal fragment of the tibia were inserted such that they were away from the future location of the plate
|Figure 2: (a) First, the Taylor spatial frame is applied. (b) One day after the surgery, soft tissue extension is initiated and continued. (c) When scheduled alignment is achieved, shortening is then performed. (d) A converting surgery is performed|
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- Soft-tissue distraction was initiated a day after the surgery at a rate of 1 mm/day [Figure 2]b. When scheduled alignment was achieved, shortening was performed until fragments were brought into contact [Figure 2]c
- Subsequently, the converting surgery was performed [Figure 2]d. First, the cancellous bone was harvested from the posterior iliac crest with the patient in the prone position. Next, the affected limb and TSF were sterilized with the patient in the supine position. The TSF antisepsis was performed by spraying the antiseptic with an atomizer. Areas that were not to be exposed were isolated with drapes. The sclerotic area was drilled for bone marrow stimulation [Figure 3]a, and thereafter, the locking plate was applied. We recommend a long-plate fixation to avoid refracture at the edge of the plate. Excision of the fibrous hamartomatous tissue was properly performed. TSF was removed, and the bone graft was placed on the pseudoarthrosis [Figure 3]b
|Figure 3: (a) The pseudoarthrosis is refreshed and drilled, (b) the locking plate is applied, the Taylor spatial frame is removed, and a bone graft is placed on the pseudoarthrosis|
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- A short leg cast was applied for immobilization, which was subsequently substituted by a patellar tendon-bearing (PTB) brace, with application of a load according to the level of bone formation. The duration of brace use was determined considering the remodeling progress. Moreover, the locking plate was not removed to prevent refracture.
| Results|| |
Bones united a mean of 3 months after the surgery, and patients walked independently with an applied load after the 56-month mean follow-up without any complications. The mean leg length discrepancy was 20.3 mm (16-24 mm).
Neurofibromatosis Type 1 with mental retardation.
The subject experienced his first bone fracture at 10 months after birth and 2 more fracture events thereafter and was subjected to 7 reconstructive surgeries in total. The first surgery was performed at 2-year-old. Procedures used for reconstructive surgery were implantation of intramedullary rods and a 6 axis external fixation. The present surgery aimed to treat the 4 th fracture [Figure 4]a. TSF was applied, and the realignment was initiated a day after the surgery. After 20 days of realignment, the converting surgery was performed [Figure 4]b. A short leg cast was applied for immobilization after the surgery, which was substituted by a PTB brace after 8 weeks, and the patient was allowed to apply a load. Tibia has united 3 months after the surgery, and the patient could walk independently 9 months after the surgery. No refracture had occurred until the last follow-up at 6 years after the surgery [Figure 4]c. The clinical examination of the left knee showed 0°of extension and 140° of flexion. The left foot had 10° of dorsiflexion and 10 of plantarflexion. The mechanical axis line passes 10mm lateral to the center of the left knee joint line. The joint orientation angles were measured according to Paley: medial proximal tibial angle (mMPTA) =97°, lateral distal tibial angle (mLDTA) =93°, posterior proximal tibial angle (mPPTA) =73°, anterior distal tibial angle (ADTA) =88°. The operated leg was 21 mm shorter than the opposite side.
|Figure 4: (a) Preoperative status. (b) after obtaining realignment, conversion to the locking plate was performed. (c) bones remained well united and had remodeled at the last follow-up (6 years after the surgery)|
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Neurofibromatosis Type 1.
The subject experienced the right lower-leg fracture at the age of 1 year, which was diagnosed as CPT. The first external fixation surgery was performed at 2 years, following which, bones united but refractured. The second external fixation performed at 5 years of age did not achieve bone union, and the pseudoarthrosis persisted. Surgery was performed in a similar manner as Case 1 [Figure 5]a and b. Tibia has united at 9 weeks after the surgery, and now (4 year after the surgery), the patient is capable of walking independently [Figure 5]c and d. The clinical examination of the right knee showed 5° of extension and 140° of flexion. The right foot had 5° of dorsiflexion and 15° of plantarflexion. The mechanical axis line passes 15 mm lateral to the center of the right knee joint line, mMPTA = 88°, mLDTA = 72°, mPPTA = 79°, ADTA = 95°. The operated leg was 24 mm shorter than the opposite side.
|Figure 5: (a and b) Preoperative radiograph (c and d) the patient was capable of walking independently 4 years after the surgery|
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The subject experienced right lower leg fracture at 3 year of age, diagnosed as CPT. The first external fixation surgery was performed at 6 years of age and the bones united once, which nevertheless refractured. The surgical operation was performed in the same procedure [Figure 6]a and b. Tibia has united at 8 weeks after the operation, and now (4 years after the operation), the patient is capable of walking independent with a PTB brace [Figure 6]c and d. The clinical examination of the right knee showed 5° of extension and 140° of flexion. The right foot had 10° of dorsiflexion and 15°of plantarflexion. The mechanical axis line passes 17 mm lateral to the center of the right knee joint line, mMPTA = 87°, mLDTA = 75°, mPPTA = 76°, ADTA = 108°. The operated leg was 16 mm shorter than the opposite side.
|Figure 6: (a and b) Preoperative radiograph (c and d) the patient was capable of walking independently 4 years after the surgery|
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| Discussion|| |
In most cases, CPT develops during infancy, and bones repeatedly fracture once united. The reason for this remains to be elucidated, but approximately 50% are manifested as a complication of neurofibromatosis. , It is important to achieve bone union during CPT treatment and to prevent re-fracture deterioration in lower leg alignment as well as an ankle joint disorder. Intramedullary rods, ,, vascularized fibular graft surgery, , and the Ilizarov method , have achieved bone union in >70% cases, , but further surgery is often necessary because of refracture, leg length discrepancies, and valgus deformity of the ankle joint.  Therefore, there is a need to develop a therapeutic method to improve treatment outcomes.
A severe shortening or bending deformity in patients with CPT is often difficult to realign because of interference between bones. It is necessary to debride adhered pseudoarthrosis and excise sclerotic bone, thereby shortening the limb. TSF employs a control device called the "Hexapod System," which expands and contracts 6 struts to realign any three-dimensional deformity. Even if bone shortening of the pseudoarthrosis is severe, TSF is capable of gradual tissue extension, allowing for an anatomical alignment with minimum leg shortening. We recommend to use the ring-type external fixator because it can not only stabilize an osteoporotic distal tibial fragment, but it also can easily correct difficult deformities. Moreover, anatomical alignment is important for refracture prophylaxis. For these reasons, TSF is useful in this surgical procedure.
Long-term external fixators are a mental and physical burden for an infant patient. Therefore, we used TSF for gradual tissue extension alone, whereas substitute locking plate fixation after realignment was used for improving the quality of life. In addition, a bone autograft from the ileum was used for transplantation to improve the bone union rate. In our method, the locking plate is not removed to prevent refracture. The plate can be removed after the patients reached skeletal maturity because the risk of refracture is small. We can prevent refracture using long-locking plate which reduces stress concentration in the junctional area at the edge of the plate. Although intramedullary rods are effective for refracture prophylaxis,  inserting rods from the calcaneus immobilize the ankle and subtalar joints and can cause significant problems such as fibrosis of the articular cartilage or ankylosis of joints. This study had a number of limitations. First, the follow-up period was relatively short. It is ideal to follow-up until skeletal maturity. Second, the fibula was not stabilized in our cases; therefore, the valgus deformity of the ankle progressed during the follow-up. We should have considered an indication of distal tibiofibular fusion to prevent it. Third, this surgical method needs multiple operations. We think it does not burden the patient because the first operation is minimally invasive. Fourth, it is difficult to demonstrate the superiority of our method, because we had no control group for comparison.
| Conclusions|| |
We obtained good outcomes in patients with refractory CPT using TSF for gradual realignment followed by a surgery for conversion to fixation with a locking plate. The present method shows promise to decreases the duration of external fixation, uses only a simple surgical technique, and prevents refracture by anatomical alignment and indwelling of a plate.
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Conflicts of interest
There are no conflicts of interest.
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