The association between fibular status and frontal plane tibial alignment post-union in congenital pseudarthrosis of the tibia

Abstract

Purpose Controversy exists regarding fibular status related to tibial alignment after congenital pseudarthrosis of the tibia (CPT) achieves union. We aimed to determine whether fibular status affected frontal plane tibial alignment post-CPT union. Methods Between January 2010 and December 2013, we followed 36 patients treated using a combined surgical technique (mean 6.6 years (2.2 to 9.4)). Outcome measures comprised medial proximal tibial angle, tibial diaphyseal angulation, lateral distal tibial angle (LDTA), relative intramedullary rod length and relative fibula length discrepancy. Results The frequency of proximal tibial valgus deformity and ankle valgus deformity were significantly lower in the fibular integrity group than in the fibular un-integrity group (proximal tibial valgus deformity: 2/17 versus 11/19; p = 0.006; ankle valgus deformity: 10/17 versus 18/19; p = 0.016). The mean LDTA was notably higher in the fibular integrity group than in the fibular un-integrity group (81.2° (sd 6.7°) versus 71.3° (sd 6.6°); p < 0.001). A statistically significant difference was observed in relative fibula length discrepancy between patients with fibular integrity (0.06 (0 to 0.11); Malhotra grade 0, n = 6; Malhotra grade I, n = 11) and those without (0.24 (0.01 to 0.36); Malhotra grade 2, n = 2; Malhotra grade 3, n = 17; p < 0.001). Ankle valgus deformity had a significant positive correlation with proximal tibial valgus deformity (r = 0.402; p = 0.015). Patients with an intact and normal length fibula had a lower frequency of ankle valgus deformity than those with an intact but shortening fibula (1/6 versus 9/11; p = 0.035). Conclusion Shortening or pseudarthrosis of the fibula was associated with ankle valgus and proximal tibial valgus deformities post-CPT union. Level of evidence III

Cross-Union Surgery for Congenital Pseudarthrosis of the Tibia

“…Proximal migration of the distal fibula is a common problem seen in patients with CPT. Migration of the fibula is related to fibular fracture and the development of valgus of the ankle plafond [ 48 , 49 , 50 ]. This subsequently leads to deformity, instability, and degeneration of the ankle joint.…”

“…Similarly, the proximal tibial physis grows into recurvatum and valgus to compensate for the procurvatum-varus diaphyseal deformity. A recent publication by Deng et al demonstrated that persistent pseudarthosis of the fibula and shortening of the fibula, even in the setting of tibial union, resulted in a statistically significant ankle and knee valgus compared to patients who had an intact fibula that maintained station [ 50 ]. The lack of loading on the tibia and the altered muscle forces, as well as the proximity of the pseudarthrosis to the distal tibial physis, lead to the slowing of the growth of the distal tibial and fibular physes and leg length discrepancy.…”

Association between preoperative concurrent fibular pseudarthrosis and risk of postoperative ankle valgus in patients with congenital pseudarthrosis of the tibia

“… 14–16 Deng et al demonstrated that shortening or pseudarthrosis of the fibula was associated with ankle valgus and proximal tibial valgus deformities. 17 However, their conclusions need to be further confirmed through a study with larger sample size. Accordingly, this study was aimed to evaluate the study findings of the correlation between the presence or absence of fibular pseudarthrosis and the risk of ankle valgus in patients with CPT showing successful healing; this study has a large sample size to identify a distinct population more likely to have postoperative ankle valgus with fibular pseudarthrosis.…”

“…Some authors believe that the presence or absence of fibular pseudarthrosis does not cause refracture of the tibia, whereas the concurrent fibular pseudarthrosis involvement is likely to cause ankle valgus deformity 14–16. Deng et al demonstrated that shortening or pseudarthrosis of the fibula was associated with ankle valgus and proximal tibial valgus deformities 17. However, their conclusions need to be further confirmed through a study with larger sample size.…”