Comparative study of different extendable intramedullary rods combined with surgery in the treatment of congenital pseudarthrosis of the tibia.

BACKGROUND: When using traditional extensible intramedullary rods to treat congenital pseudarthrosis of the tibia (CPT), there were cases of re-fracture and internal fixation fracture. Therefore, the authors propose a research hypothesis that a thicker distal extensible intramedullary rod can better protect the tibia and reduce the incidence of refracture PURPOSE: To investigate the clinical efficacy of new and traditional extensible intramedullary rods in the treatment of CPT in children METHODS: From January 2017 to December 2021, the clinical data of 49 children with CPT who were treated with traditional extensible intramedullary rod combined surgery (group A) and new extensible intramedullary rod combined surgery (group B) in our hospital were collected. Inclusive criteria: ① Crawford type IV CPT children; ② The operation was performed by the same team. EXCLUSION CRITERIA: patients with multiple tibial angulation. During follow-up, the initial healing, proximal tibial valgus, tibial length, ankle valgus, refracture and intramedullary rod displacement of CPT children in the two groups were evaluated RESULTS: It was a retrospective investigation. In group A, 26 cases met the inclusion criteria, 24 cases achieved primary healing, with an primary healing rate of 92%, including 1 case of nonunion due to osteomyelitis complications after surgery, and 1 case of delayed healing, with an average healing time of 4.7 ± 0.8 months. 17 cases (68%) had unequal tibia length, with an average difference of 1.6 ± 0.8 cm. Ankle valgus occurred in 10 cases (40%) with an average of 14.4°±4.8°; Proximal tibial valgus occurred in 6 cases (24%) with an average of 7 °± 1.8 °. 20 cases (80%) had tip of the rod migration.10 cases (40%) had re-fracture; The average follow-up time was 2.4 ± 0.4 years. In group B, 22 patients achieved primary healing, and the primary healing rate was 95%, including 1 case with delayed healing. The average healing time was 4.7 ± 1.7months. 14 cases (61%) had unequal tibia length, with an average difference of 1 ± 0.5 cm. Ankle valgus occurred in 4 cases (17%) with an average of 12.3 °±4.9°; The proximal tibia valgus occurred in 9 cases (39%), with an average of 7.7 °±2.5 °. 14 cases (61%) had new type of intramedullary rod displacement. 3 cases (13%) had re-fracture; The average follow-up time was 2.3 ± 0.6years CONCLUSION: Compared with the traditional extended intramedullary rod combined operation, the new type of extended intramedullary rod combined operation has a lower incidence of re-fracture after CPT, but it still needs to be verified by large sample and multi-center research.

Is physeal distraction osteogenesis a good choice to treat CPT patients with tibial shortening?

The purpose of this study was to evaluate the healing index and complications of distraction osteogenesis through the physis in children with Congenital pseudarthrosis of the tibia (CPT) using Ilizarov external fixation device. Nine children with CPT who underwent distraction osteogenesis through the physis surgery with an Ilizarov external fixation device between June 2018 and August 2020 were included in the study. The average follow-up time was 36.1 months. X-ray examination was performed 1 month after physis lengthening, and the callus quality was evaluated using the Li classification. Any complications and the quality of the callus after tibial lengthening were followed up. The average age at the time of operation was 9.4 years, and the average follow-up time was 36.1 months. The average lengthening length of children with CPT was 6.6 cm. The incidence of good callus morphology was 100%, and the healing index was 51.1 d/cm. The average fixation time of the external fixation device was 316 days. Needle tract infection occurred in one case, ankle stiffness occurred in one case, ankle plantar flexion 20° deformity occurred in one case, angular deformity of the tibial lengthening segment occurred in one case (7°) and limited movement of knee joint occurred in one case (0-20°-70°). The osteogenic quality of the patients of distraction osteogenesis through the physis with tibial shortening and small diameter of the proximal tibia is good, which provides a choice of operation for the children with CPT.

Clinical study of a new type of telescopic rod for the treatment of congenital pseudarthrosis of the tibia in children.

The purpose of this study was to investigate the initial efficacy of a new telescopic rod in the treatment of congenital pseudarthrosis of tibia (CPT) in children. A new type of telescopic rod for children was designed and its clinical results were evaluated. There were nine cases of CPT on the right and six cases on the left; there were six females and nine males. The average age at operation was 35.5 months. There were 12 cases with neurofibromatosis type 1 and 4 cases with proximal tibial dysplasia. The initial healing of tibial pseudarthrosis, proximal tibial valgus deformity, tibial length, ankle valgus, ankle function, and intramedullary rod displacement were evaluated during follow-up. All 15 cases were followed up for an average of 18.2 months, 14 cases achieved initial healing, with an average healing time of 4.3 months. Ten cases had unequal lengths of the tibia, with an average of 0.9 cm. Proximal tibial valgus occurred in seven cases and ankle valgus occurred in one child. The average range of motion of the ankle joint was 23° and the average plantar flexion was 42°. The average extension of the new telescopic rod was 1.6 cm. The displacement of the telescopic rod occurred in seven cases, there was no epiphyseal plate tethering and re-fracture. The new children's telescopic rod has a reasonable design and can extend with the growth of tibia. There are no complications of epiphyseal plate tethering and re-fracture. It provides a new choice of intramedullary fixation for the treatment of CPT.

New insights into pathogenesis of congenital pseudarthrosis of tibia in children using periosteum proteomics analysis.

RATIONALE: The exact etiology and pathogenesis of congenital pseudarthrosis of tibia (CPT) are not clear. Quantitative proteomics analysis plays a vital role in disease pathology research. Tandem mass tag (TMT)-based proteomics techniques were employed to identify and analyze the differentially expressed proteins (DEP) in the tibia periosteum tissues of CPT patients. METHODS: The samples were divided into three groups: CPT with NF1 group, CPT without NF1 group (non-NF1-CPT), and control group (patients with open tibial fracture). A fold change ≥1.5 or ≤0.66 and P-value <0.05 were used as the thresholds to screen DEPs. Subsequently, bioinformatics resources such as online tools DAVID and String were used to generate gene ontology (GO) annotation, KEGG pathways enrichment, and protein-protein interaction (PPI) network for these DEPs. RESULTS: The results show that a total of 347 proteins were differentially expressed in NF1-CPT groups, 212 of which were upregulated and 135 were downregulated. There were more DEPs in non-NF1-CPT groups; we identified 467 DEPs, including 281 upregulated and 186 downregulated. Among them, NF1-CPT groups and non-NF1-CPT groups shared 231 DEPs, and the remaining 230 DEPs showed the same expression trend in the two disease groups, with 117 upregulated and 113 downregulated. In particular, 116 proteins were altered only in NF1-CPT groups (94 were upregulated and 22 were downregulated), whereas 236 proteins were altered only in non-NF1-CPT groups (164 were upregulated and 72 were downregulated). Finally, compared with non-NF1-CPT groups, 47 proteins changed 1.5-fold and P-value < 0.05 in NF1-CPT groups. CONCLUSIONS: To sum up, we found that common DEPS in periosteum of NF1-CPT and non-NF1-CPT groups are mainly involved in cell matrix assembly, cell adhesion, AKT-PI3K signal pathway activation, and vascular agglutination, which indicate that these are the pathological characteristics of CPT. The osteogenic ability is weak, the osteoclastic ability is strong, the vascular lumen is narrow, the invasive growth and the proliferation of fibroblasts are enhanced in CPT patients.

Analysis of risk factors affecting union and refracture after combined surgery for congenital pseudarthrosis of the tibia: a retrospective study of 255 cases.

BACKGROUND: Congenital pseudarthrosis of the tibia (CPT) is a rare disease occurring in children. The aim of this study is to identify the factors affecting bone union and re-fracture after surgery for CPT and to provide reliable evidence for clinics. METHODS: We collected the detailed information of 255 cases with Crawford IV CPT treated by combined surgery in our hospital from 2013 to 2020. Basic characteristics were recorded. Univariate variance and logistic regression analysis were used to compare the correlations between factors and outcomes. RESULTS: 92.5% of patients achieved primary union, 7.5% of patients had non-union and 13.3% of patients had re-fracture. Logistic regression analysis showed that age at index surgery (Coef. = 0.171, 95%CI 0.015-0.327, P = 0.032), and CPT location (Coef. = - 1.337, 95%CI - 2.218-0.456, P = 0.003) had statistical differences, while no factors had significant correlation with re-fracture. Furthermore, ROC curve showed that the optimal age threshold for first surgery was 2.37 years old. CONCLUSIONS: For patients with Crawford IV CPT treated by combined surgery, the younger the age at index surgery and the closer the CPT location to the distal end, the easier to achieve bone union.

Are Children Suffering From Congenital Pseudarthrosis of the Tibia Associated With Decreased Bone Strength?

Background: Congenital pseudarthrosis of the tibia (CPT) is a rare and difficult-to-treat congenital disease in neonates. Our previous study found that exosomes derived from serum of children with CPT inhibit bone formation. In this study, we used ultrasound bone densitometry to detect the bone strength differences between hospitalized children with CPT and with non-metabolic diseases to determine the bone strength of children with CPT. Methods: A total of 37 children with CPT with a mean age of 3.14 ± 1.81 years and 40 hospitalized children with a mean age of 3.32 ± 2.66 years with supracondylar fracture of the humerus and without a bone metabolic disease (control group) were recruited in our hospital. The ultrasonic bone densitometer was used to examine the bilateral calcaneus of the subjects. We collected the broadband ultrasonic attenuation (BUA), speed of sound (SOS), quantitative ultrasound index (QUI), bone strength index (STI) and bone mineral density estimation (BMDe) values. Multivariable regression was used to examine the associations between quantitative ultrasound measurement differences and age, body mass index (BMI), neurofibromatosis type 1 (NF1) and CPT Crawford type. Intra-class correlation coefficient (ICC) was calculated to estimate intra- and inter-rater agreements. Results: 74 calcaneus scans were taken from CPT patients (23 boys and 14 girls) and 80 calcaneus scans were taken from the control (24 boys and 16 girls). The CPT patients exhibited significantly lower SOS (1,368.75 ± 136.78 m/s), STI (7.2319 ± 38.6525), QUI (8.2532 ± 56.1720), and BMDe (-0.0241 ± 0.3552 g/cm3) than the control (SOS: 1,416.02 ± 66.15 m/s, STI: 7.96 ± 16.884, QUI: 28.8299 ± 25.461, BMDe: 0.0180 ± 0.1610 g/cm3). Multiple regression revealed that SOS, STI and QUI were statistically significant and negatively correlated with CPT Crawford classification. Conclusions: We found the incidence of decreased bone strength in CPT group was higher than that in the non-bone metabolic disease group. This phenomenon was not related to NF1 but related to CPT Crawford classification, which suggested that the higher the grade of the CPT Crawford classification, the lower the bone strength and the higher the risk of fracture.

Evaluation of the efficacy of ipsilateral fibular transfer for reconstruction of large tibial defects in children: a retrospective study.

BACKGROUND: Reconstruction of large tibial defects is often a major challenge in limb salvage. This study aimed to evaluate initial follow-up results of ipsilateral fibula transfer for the treatment of large tibial defects in children. METHODS: A retrospective study was performed between September 2014 and April 2021. Ten children were identified as having large tibial defects. The children underwent ipsilateral fibula transfer. We then evaluated initial healing, tibial length discrepancy, ankle varus/valgus, fibular position, refracture, infection, and function. RESULTS: Five boys and five girls, with an average age of 7.2 years, were evaluated. The transferred fibula was united in the patients. The mean follow-up period after fibular transposition was 43 months. The patients achieved primary bone union; the mean time to union was 8.4 months (range, 4-18 months). Complications included refracture (30%), infection (40%), tibia malunion (30%), ankle varus (30%), sensory loss of toes (10%), and ankle valgus (10%). No other major complications were observed. All 10 patients were able to perform activities of daily living and return to their normal activities. CONCLUSION: Ipsilateral fibula transfer is a salvage surgery for the treatment of large tibial defects in children with congenital pseudoarthrosis of the tibia, traumatic nonunion of the tibia, and/or tibial defect after chronic osteomyelitis. However, long-term results still need to be followed up.

Case series of congenital pseudarthrosis of the tibia unfulfilling neurofibromatosis type 1 diagnosis: 21% with somatic NF1 haploinsufficiency in the periosteum.

Up to 84% of patients with congenital pseudarthrosis of the tibia (CPT) present with neurofibromatosis type 1 (NF1) (NF1-CPT). However, the etiology of CPT not fulfilling the NIH diagnostic criteria for NF1 (non-NF1-CPT) is not well understood. Here, we collected the periosteum tissue from the pseudarthrosis (PA) site of 43 non-NF1-CPT patients and six patients with NF1-CPT, together with the blood or oral specimen of trios (probands and unaffected parents). Whole-exome plus copy number variation sequencing, multiplex ligation-dependent probe amplification (MLPA), ultra-high amplicon sequencing, and Sanger sequencing were employed to identify pathogenic variants. The result showed that nine tissues of 43 non-NF1-CPT patients (21%) had somatic mono-allelic NF1 inactivation, and five of six NF1-CPT patients (83.3%) had bi-allelic NF1 inactivation in tissues. However, previous literature involving genetic testing did not reveal somatic mosaicism in non-NF1-CPT patients so far. In NF1-CPT patients, when the results from earlier reports and the present study were combined, 66.7% of them showed somatic NF1 inactivation in PA tissues other than germline inactivation. Furthermore, no diagnostic variants from other known genes (GNAS, AKT1, PDGFRB, and NOTCH3) related to skeletal dysplasia were identified in the nine NF1 positive non-NF1-CPT patients and six NF1-CPT patients. In conclusion, we detected evident somatic mono-allelic NF1 inactivation in the non-NF1-CPT. Thus, for pediatric patients without NF1 diagnosis, somatic mutations in NF1 are important.

Application of the "telescopic rod" in a combined surgical technique for the treatment of congenital pseudarthrosis of the tibia in children.

BACKGROUND: The current surgical treatment of choice is the combination surgical technique, involving tibial intramedullary fixation to maintain the mechanical axis and mechanical stability of tibial pseudarthrosis. In traditional combined surgery, the Williams rod is often used. Long-term intramedullary fixation of the foot and ankle will affect the ankle joint function of children. The intramedullary rod is relatively shorter due to the growth of the distal tibia. In addition, there are some complications such as epiphyseal bone bridge and high-arched foot. The use of a telescopic intramedullary rod may avoid these complications. PURPOSES: To investigate the initial effect of the "telescopic rod" in a combined surgical technique for the treatment of congenital pseudarthrosis of the tibia in children. METHODS: A retrospective study including 15 patients with Crawford type IV CPT who were treated using a combined surgical technique and the telescopic rod from January 2017 to May 2018. The average age at the time of surgery was 43.3 months (16-126 months). Of the 15 patients, 7 had proximal tibia dysplasia and 12 exhibited neurofibromatosis type 1. The combined surgical technique using the telescopic rod included the excision of pseudarthrosis, intramedullary rod insertion, installation of Ilizarov's fixator, tibia-fibular cross union, and wrapping autogenic iliac bone graft. The incidence of refracture, ankle valgus, tibial valgus, and limb length discrepancy (LLD) in patients were investigated. RESULTS: All patients achieved primary union with an average follow-up time of 37.3 months (26-42 months). The mean primary union time was 4.5 months (4.0-5.6 months). Nine cases showed LLD (60%), with an average limb length of 1.1 cm (0.5-2.0 cm). Ankle valgus, proximal tibial valgus, telescopic rod displacement, and epiphyseal plate tethering occurred in 1 case (6.6%) (18°), 3 cases (20%) (10°, 5°, and 6°, respectively), 6 cases (40%), and 2 cases (13%), respectively. There were no refractures during the follow-up periods. CONCLUSION: Although there are complications such as intramedullary rod displacement while using the telescopic rod in a combined surgery, the primary healing rate of congenital pseudarthrosis of the tibia in children is high.

Serum-derived exosomes from neurofibromatosis type 1 congenital tibial pseudarthrosis impaired bone by promoting osteoclastogenesis and inhibiting osteogenesis.

Treatment of congenital pseudarthrosis of the tibia (CPT) still is full of challenges in pediatric orthopedist. Serum-derived exosomes (SDEs) have been proven to be participated in bone remodeling. However, the molecular changes in SDEs of CPT children and their pathologies have not been elucidated. In this study, SDEs were isolated and purified from CPT patients (CPT-SDEs) associated with neurofibromatosis type 1 (NF1) and normal children (Norm-SDEs). Then we obtained the proteomics profile of SDEs by combining liquid chromatography-tandem mass spectrometry (LC-MS/MS) and tandem mass tag label-based quantitation. In vitro, the efficacy of SDEs on osteoblastic differentiation of MC3T3-E1 cells and osteoclastogenesis ability of RAW264.7 cells were evaluated by quantitative real-time PCR (qRT-PCR) and cytochemical staining. In vivo, we used micro-CT to assess cortical bone mass and trabecular microstructures to reflect the influence of SDEs on bone remodeling after injection into the tail vein of rats. Based on proteomics analysis, 410 differentially expressed proteins, including 289 downregulated proteins and 121 upregulated proteins, were identified in the CPT-SDEs. These proteins have multiple biological functions associated with cellular metabolic processes, catalytic activity, and protein binding, which are important for cell differentiation and proliferation. In vitro, CPT-SDEs decreased the osteogenic differentiation of MC3T3-E1 cells and promoted the osteoclastogenesis of RAW264.7 cells. Injection of CPT-SDEs into the tail vein for two months resulted in bone loss in rats, as indicated by the decrease in trabecular and cortical bone mass. Our findings demonstrated the differences in proteins in SDEs between normal and CPT children with NF1. These differentially expressed proteins in CPT-SDEs contributed to deteriorating trabecular bone microstructures by inhibiting bone formation and stimulating bone resorption.

The neurofibromatosis type I gene promotes autophagy via mTORC1 signalling pathway to enhance new bone formation after fracture.

Bone fracture is one of the most common injuries. Despite the high regenerative capacity of bones, failure of healing still occurs to near 10% of the patients. Herein, we aim to investigate the modulatory role of neurofibromatosis type I gene (NF1) to osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and new bone formation after fracture in a rat model. We studied the NF1 gene expression in normal and non-union bone fracture models. Then, we evaluated how NF1 overexpression modulated osteogenic differentiation of BMSCs, autophagy activity, mTORC1 signalling and osteoclastic bone resorption by qRT-PCR, Western blot and immunostaining assays. Finally, we injected lentivirus-NF1 (Lv-NF1) to rat non-union bone fracture model and analysed the bone formation process. The NF1 gene expression was significantly down-regulated in non-union bone fracture group, indicating NF1 is critical in bone healing process. In the NF1 overexpressing BMSCs, autophagy activity and osteogenic differentiation were significantly enhanced. Meanwhile, the NF1 overexpression inhibited mTORC1 signalling and osteoclastic bone resorption. In rat non-union bone fracture model, the NF1 overexpression significantly promoted bone formation during fracture healing. In summary, we proved the NF1 gene is critical in non-union bone healing, and NF1 overexpression promoted new bone formation after fracture by enhancing autophagy and inhibiting mTORC1 signalling. Our results may provide a novel therapeutic clue of promoting bone fracture healing.

Combined surgery with 3-in-1 osteosynthesis in congenital pseudarthrosis of the tibia with intact fibula.

BACKGROUND: Re-fracture is the most serious complication in congenital pseudarthrosis of the tibia (CPT). There are reports that children with small cross-sectional areas in the sections of the pseudarthrosis are more prone to re-fracture. Presently, preventing complications is a challenge. Increasing the cross-sectional area in healed segments may reduce the incidence of re-fracture. PURPOSE: To elucidate the indications, surgical technique, and outcomes of combined surgery and 3-in-1 osteosynthesis in CPT with intact fibula. METHODS: We retrospectively assessed 17 patients with Crawford Type IV CPT with intact fibula (Type A) who were treated with combined surgical technique and 3-in-1 osteosynthesis between March 2014 and August 2015. The average age of the patients at the time of surgery was 3 years. Incidence of re-fracture, ankle valgus, proximal tibial valgus, and limb length discrepancy (LLD) were investigated over an average follow-up time of 47 months. RESULTS: Primary union was achieved in all patients. The average time for primary union was 4.9 months. Fifteen (88%) cases showed LLD with an average limb length of 1.6 cm; 6 (35%) cases exhibited tibial valgus with an average tibial valgus deformity of 7.8°; 2 cases had ankle valgus, wherein the ankle valgus deformity was 12° in one and 17° in another; and the cross-sectional area of the bone graft was enlarged to 1.74 times that of the tibia shaft. No case had re-fracture during the follow-up period. Movement of the ankle joint was restored in 16 patients with an average dorsiflexion of 22° and an average plantar flexion of 41°; the function of the ankle joint was normal. One patient had plantar flexion of 20° but did not have dorsiflexion. CONCLUSION: Combined surgical technique with 3-in-1 osteosynthesis, which is primarily considered for bone union with a large cross-sectional area, results in a high primary union rate. This can provide satisfactory results in short-term follow-up when treating CPT with intact fibula (Type A).

Identification and characterization of NF1 and non-NF1 congenital pseudarthrosis of the tibia based on germline NF1 variants: genetic and clinical analysis of 75 patients.

BACKGROUND: Congenital pseudarthrosis of the tibia (CPT) is a rare disease. Some patients present neurofibromatosis type 1 (NF1), while some others do not manifest NF1 (non-NF1). The etiology of CPT, particularly non-NF1 CPT, is not well understood. Here we screened germline variants of 75 CPT cases, including 55 NF1 and 20 non-NF1. Clinical data were classified and analyzed based on NF1 gene variations to investigate the genotype-phenotype relations of the two types of patients. RESULTS: Using whole-exome sequencing and Multiplex Ligation-Dependent Probe Amplification, 44 out of 55 NF1 CPT patients (80.0%) were identified as carrying pathogenic variants of the NF1 gene. Twenty-five variants were novel; 53.5% of variants were de novo, and a higher proportion of their carriers presented bone fractures compared to inherited variant carriers. No NF1 pathogenic variants were found in all 20 non-NF1 patients. Clinical features comparing NF1 CPT to non-NF1 CPT did not show significant differences in bowing or fracture onset, lateralization, tissue pathogenical results, abnormality of the proximal tibial epiphysis, and follow-up tibial union after surgery. A considerably higher proportion of non-NF1 patients have cystic lesion (Crawford type III) and used braces after surgery. CONCLUSIONS: We analyzed a large cohort of non-NF1 and NF1 CPT patients and provided a new perspective for genotype-phenotype features related to germline NF1 variants. Non-NF1 CPT in general had similar clinical features of the tibia as NF1 CPT. Germline NF1 pathogenic variants could differentiate NF1 from non-NF1 CPT but could not explain the CPT heterogeneity of NF1 patients. Our results suggested that non-NF1 CPT was probably not caused by germline NF1 pathogenic variants. In addition to NF1, other genetic variants could also contribute to CPT pathogenesis. Our findings would facilitate the interpretation of NF1 pathogenic variants in CPT genetic counseling.

Congenital pseudarthrosis of the tibia in children: should we defer surgery until 3 years old?

Currently, the timing of surgery for congenital pseudarthrosis of the tibia (CPT) remains controversial. The aim of this study was to investigate the results of treatment of pseudarthrosis of the tibia in children younger than 3 years of age. A retrospective study was carried out to explore the relationship between postoperative complications and the age of surgery in children with CPT. The analysis was carried out on 42 patients with Crawford type IV CPT treated with a combined surgical technique between 2008 and 2012. Patients were divided into two groups according to their age: group A (<3 years) and group B (>3 years). The incidence rates of refracture, ankle valgus, tibial valgus, and limb-length discrepancy of the two groups were evaluated. Primary bone union was achieved in 28 out of 29 (97%) patients in group A and 12 out of 13 (92%) patients in group B (P>0.05). In group A, six (21%) patients developed a refracture; 14 (48%) patients had ankle valgus with a mean degree of 11° (range: 5°-25°); 11 (38%) patients had tibial valgus with a mean tibial valgus deformity of 8.6° (range: 5°-20°); and 12 (41%) patients had limb-length discrepancy with a mean limb length of 2.9 cm (range: 0.5-4 cm). In group B, five (38%) patients developed refracture; seven (54%) patients had ankle valgus with a mean degree of 14° (range: 5°-30°); seven (54%) patients had tibial valgus with a mean tibial valgus deformity of 10.7° (range: 5°-20°); and 10 (77%) patients had limb-length discrepancy with a mean limb length of 2.8 cm (range: 1.5-3 cm). Groups A and B were significantly different in limb-length discrepancy (P=0.033). This study suggests that there is no need to defer surgery for pseudarthrosis of the tibia until the child is older than 3 years of age.

Combination of intramedullary rod, wrapping bone grafting and Ilizarov's fixator for the treatment of Crawford type IV congenital pseudarthrosis of the tibia: mid-term follow up of 56 cases.

BACKGROUND: The purpose of this study was to investigate the initial union rate, refracture rate and residual deformities of congenital pseudarthrosis of the tibia (CPT), using combined surgery including pseudarthrosis resection, intramedullary rodding, autogenous iliac bone grafting and Ilizarov's fixator, with a mean 5.2 years follow-up. METHODS: We retrospectively reviewed the records and diagrams of patients with Crawford type IV congenital pseudarthrosis of the tibia between February 2007 and March 2010. Patients managed by pseudarthrosis resection, intramedullary rod of the tibia, wrapping autogenous iliac bone grafting and Ilizarov's fixator were enrolled. We evaluated the bone union rate, tibial alignment, limb length discrepancy (LLD), valgus deformity of the ankle and the frequencies of refracture during period of follow-up. RESULTS: There were 56 cases enrolled in the study, with a mean follow-up 5.2 years (range, 3 to 6.7 years). The mean age of the patients at surgery was 3.5 years (range, 1.5 to 12.4 years). Fifty (89.2 %) of the 56 patients had primary bone union at site of pseudarthrosis, while 5 obtained union after second surgery and 1 failed. The average time spent to obtain pseudarthrosis initial union was 4.5 months (range, 3.0 to 10.0 months) and mean duration of Ilizarov treatment was 4.7 months (range, 3.2 to 10.4 months). Eleven (19.6 %) patients had proximal tibial valgus with a mean angle of 9.5° (range, 5 to 24°), while 10 (17.9 %) patients had ankle valgus deformities with a mean of 12.3° (range, 6 to 21°). Sixteen (28.6 %) patients had an average 2.2 cm LLD (range, 1.5-4.2 cm). Of the 50 cases who obtained initial bone union of pseudarthrosis, 13 (26.0 %) had refracture which need cast immobilization or secondary surgery. CONCLUSIONS: This combined surgery obtained initial union rate of 89.2 % at primary surgery while the refracture rate is 26.0 %. However, residual deformities such as proximal tibial valgus, LLD and ankle valgus were also existed which should be pay more attention to and dealt with. TRIAL REGISTRATION: This study was registered in ClinicalTrials.gov under the name "The Effect of Combined Surgery in Management of Congenital Pseudarthrosis of Tibia" ( NCT02640040 ), which was released on August 31, 2015.