| Objectives: Congenital pseudarthrosis of the tibia(CPT)whose etiology and mechanism are not clear until now is a rare disease occurring in children and always concomitant with NF-1(Neurofibromatosis type,1).It is mainly characterized by anterolateral bowing of the middle and lower 1/3 of the tibia that gradually results in difficulty healing pathological fracture.Once CPT is formed,surgery is the only effective treatment.In recent decades,the primary bone healing rate of CPT has been significantly improved by the vascularized fibular grafting,bone grafting and Ilizarov’s fixator,bone grafting combined with intramedullary rod fixation,and the combined technique.But refracture and tibial malalignment are still not avoided.Although CPT achieved bone union,tibial malalignment will impair the weight-bearing walking function.Some authors suggest that the intramedullary rod can maintain a good tibial axis,but tibial malalignment still occurs.At the same time,some authors suggest that an intact fibula can maintain a better tibial alignment and prevent refracture,but some researchers believe tibial malalignment was independent of fibular pseudarthrosis.At present,controversy exists regarding risk factors related to clinical results after CPT achieves union.The treatment methods are different and the homogeneity is poor among the studies,so the reported results are inconsistent.In this study,all patients were treated with the combined surgery.If we can identify the related risk factors affecting the clinical results,we can not only further reduce the incidence of tibial deformity and refracture after CPT obtains union,but also provide a foundation for children’s long-term good weight-bearing walking function.Methods:This study is divided into three parts.1.Analysis of affected factors of clinical results after CPT achieves union treated with the combined surgeryThe follow-up data of CPT treated with combined surgery from January 1,2010 to December 31,2014 were collected retrospectively.The evaluation indexes included tibial diaphyseal angulation,bilateral tibial length difference,refracture and Johnston classification of clinical results.At the end of follow-up,univariate analysis was conducted on the clinical results of each group with or without operation history,gender,whether combined with NF-1,age at the time of operation,and fibular status.Statistically significant factors(P<0.1)or clinically valuable factors were selected and performed the ordinal polytomous logistic regression to identify the risk factors of clinical results.2.Analysis of risk factors of refracture after healing of congenital pseudarthrosis of the tibia treated with the combined surgeryThe follow-up data of CPT treated with the combined surgery from January 1,2010 to December 31,2014 were collected retrospectively.The evaluation indexes included the ratio of the cross-sectional area of pseudarthrosis healing site and refracture-free survival time,and the factors that may lead to refracture were analyzed by univariate analysis.Statistically significant factors(P<0.1)and the factors with clinical value were selected and performed the Cox proportional hazards regression to obtain the risk factors related to refracture.3.The association between fibular status and tibial alignment post-union in congenital pseudarthrosis of the tibia treated with the combined surgeryThe medical records of patients with CPT,who were diagnosed and treated by the combined surgery at the authors’ institution between January 1 2010 and December 312013,were analyzed retrospectively.According to whether the fibula was intact at the last follow-up,it was divided into the fibular integrity group the and fibular pseudarthrosis group.The evaluation indicators included the medial proximal tibial angle(MPTA),tibial diaphyseal angulation,the lateral distal tibial angle(LDTA),proximal posterior tibial angle(PPTA),and anterior distal tibial angle(ADTA),the relative intramedullary rod length,and Relative fibula length discrepancy were analyzed statistically.Results:1.At the last follow-up,52 cases that had a mean follow-up time of 7.0 years(2.2years～11.1years)were obtained.12 cases had operation history.The clinical results were50% in grade I,8.3% in grade II,and 41.7% in grade III in the operation history group;40 cases had no operation history.The clinical results were 60% in grade I,15% in grade II,and 25% in grade III in the no operation history group;There was no significant difference between the two groups in tibial diaphyseal angulation,bilateral tibial length difference,and clinical results grade(P>0.05).There were 33 cases in the male group and the clinical results were 64% in grade I,12% In grade II,and 24% in grade III;There were 19 cases in the female group and the clinical results were 47% in grade I,16% in grade II,and 37% in grade III;There was no significant difference between the two groups in tibial diaphyseal angulation,tibial length difference and clinical outcome(P>0.05).There were 38 cases in the NF-1 group and the clinical results were 63% in grade I,13% in grade II and,24% in grade III;There were 14 cases in the without NF-1group and the clinical results were 43% in grade I,14% in grade II and 43% in grade III;There was no significant difference between the two groups in tibial diaphyseal angulation,bilateral tibial length difference and clinical outcome(P>0.05).There were32 cases in the group aged <3 years at the time of operation and the clinical results were56% in grade I,13% in grade II,and 31% in grade III;There were 20 cases in the group aged ≥3 years at the time of operation and the clinical results were 60% in grade I,15%in grade II and 25% in grade III;There was no significant difference between the two groups in tibial diaphyseal angulation,bilateral tibial length difference and clinical results grade(P>0.05).There were 24 cases in the fibular integrity group and the clinical results were 79.2% in grade I,4.2% in grade II,and 16.6% in grade III;There were 28 cases in the fibular pseudarthrosis group and the clinical results were 39.3% in grade I,21.4% in grade II and 39.3% in grade III;There was no significant difference in tibial diaphyseal angulation and bilateral tibial length between the two groups(P>0.05),but there was a significant difference in clinical results grade between the two groups(P=0.008).The results of ordinal polytomous logistic regression analysis indicated that the fibular status had a statistically significant effect on the clinical results(OR=6.179,P=0.006).2.At the last follow-up,There was no significant difference in refracture-free survival rate between different gender,and age at operation,with or without NF-1(P>0.05).The average refracture-free survival time of the fibular integrity group was 113 months,and that of the fibular pseudarthrosis group was 78 months.There was a significant difference in refracture-free survival rate between the two groups(P=0.005).The ratio of the cross-sectional area of the pseudarthrosis healing site was larger than 0.17(≥0.17),and the average refracture-free survival time was 113 months.The ratio of the crosssectional area of the pseudarthrosis healing site was less than 0.17(<0.17),and the refracture-free survival time was 73 months.There was a significant difference in refracture-free survival rate between the two groups(P=0.005).Cox proportional hazards regression analysis presented that the cross-sectional area of the pseudarthrosis healing site and fibular status had a statistically significant effect on the refracture-free survival rate(OR=0.210,4.541,respectively,P < 0.05).3.At the last follow-up,36 cases had a mean follow-up time of 7.3 years(2.2 years～11.1years).There were 17 cases in the fibular integrity group and 19 cases in the fibular pseudarthrosis group.The mean value of MPTA in the fibular integrity group was 90.3°±3.3° and proximal tibial valgus deformity occurred in 2 cases(11.8%).The mean value of MPTA in the fibular pseudarthrosis group was 93.4°± 6.2° and 11 cases(57.9%)presented proximal tibial valgus deformity.There was no significant difference in MPTA between the two groups(P=0.077),but there was a significant difference in proximal tibial valgus deformity(P=0.006).There was no significant difference in tibial diaphyseal angulation between the two groups.No patients manifested tibial diaphyseal varus deformity and no between-group statistical differences were found in terms of tibial coronal diaphyseal angulation and valgus deformity(P>0.05).The mean value of LDTA in the fibular integrity group was 81.2°± 6.7°,and that in the fibular pseudarthrosis group was 71.3°± 6.6°.There was a significant difference in LDTA between the two groups(P<0.001).There were 10 cases(58.8%)with ankle valgus deformity in the fibular integrity group and 18 cases(94.7%)had ankle valgus deformity in the fibular pseudarthrosis group.There was a significant difference in ankle valgus deformity between the two groups(P=0.016).There was no significant difference in the relative length of the intramedullary rod and follow-up time between the two groups(P>0.05).There was a significant statistical difference in fibular shortening between the two groups(P<0.001),which was negatively correlated with LDTA(correlation coefficient r =-0.694,P<0.001).There was a significant positive correlation between ankle valgus and proximal tibial valgus deformity(r=0.402,P=0.015).The mean value of PPTA in the fibular integrity group was lower than that in the fibular pseudarthrosis group(84.9°±4.6°,85.8°±3.8°,respectively),but there was no significant difference between the two groups(P>0.05).Five cases(29%)had proximal tibial recurvatum deformity in the fibular integrity group and 5 cases(26%)had proximal tibial recurvatum deformity in the fibular pseudarthrosis group.There was no significant difference in proximal tibial deformity between the two groups(P>0.05).Regardless of the quantitative or qualitative analysis of tibial sagittal diaphyseal angulation,there was no significant difference existed between the two groups(P>0.05).No patients presented proximal tibial procurvatum deformity and distal tibial recurvatum deformity.The mean value of ADTA in the fibular integrity group was 90.2°±6.1°and 11 cases(65%)had distal tibial procurvatum deformity.The mean value of ADTA in the fibular pseudarthrosis group was 92.7°±5.7°and 18 cases(95%)had distal tibial procurvatum deformity.There was no significant difference in ADTA between the two groups(P>0.05),but there was a significant difference in distal procurvatum deformity(P=0.037).Conclusion:1.Fibular status can affect the clinical results after CPT healing treated with the combined surgery and maintaining the integrity of fibula can obtain better clinical results.2.In order to decrease the risk of refracture,we should maintain fibular integrity and achieve a larger cross-sectional area of the pseudarthrosis healing site.3.Fibular pseudarthrosis or shortening can affect the distal tibial alignment,resulting in ankle valgus deformity and distal tibial procurvatum deformity,and there is a correlation between ankle valgus and proximal tibial valgus deformity. |
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