Isolated congenital pseudoarthrosis of the fibula: a comparison of fibular osteosynthesis with distal tibiofibular synostosis

Refracture, a Potential Complication of the Periosteal Flap Technique Without Bone Graft for Isolated Congenital Pseudarthrosis of the Fibula: A Report of Two Cases and Literature Review

BACKGROUND

It is a rare condition defined by congenital pseudarthrosis of the fibula (CPF), which may be associated with neurofibromatosis (NF) and congenital pseudarthrosis of the tibia. A condition such as this may be symptomatic or asymptomatic, but it requires treatment because of the progression of signs such as ankle valgus and pseudarthrosis of the tibia. There are a number of surgical techniques that can be used to treat this condition, such as tibiofibular fusion, internal fixation, the Ilizarov method, and periosteal flap.

AIM

The goal of this study was to describe the treatment results of two patients with CPF using vascularized fibular periosteal flaps.

CASE REPORT

We described the case of a 5-year-old patient and a 19-month-old patient with isolated CPF. Both patients underwent a distal-based vascularized fibular periosteal flap, and intramedullary fixation was used to treat the patients.

CONCLUSION

The patients had full union in the pseudarthrosis site, but in the end, both had asymptomatic refracture in the union site. Our experiences showed that it is necessary to use strong intramedullary fixation and bone graft.

Nonvascularized fibular harvest in children: impact on donor limbs

Nonvascularized fibular graft is commonly used in children. We investigated periosteal intactness, proportion of harvested fibula and the distal remnant for their association to regeneration and development of ankle valgus in 25 donor limbs (n = 18 patients). The fibulae were harvested from healthy legs with all possible care to preserve periosteum. Intraoperatively, periosteal breach and length of graft obtained were recorded. Follow-up radiographs at 6 months documented lateral distal tibial angle, fibular station, and longitudinal continuous regeneration of fibula in the donor limb. Limbs with and without regeneration/ankle valgus were matched for proportion of harvested length and distal remnant, respectively. Odds ratios for periosteum breach versus nonregeneration and nonregeneration versus ankle valgus were additionally calculated. The average harvest length and distal remnant were 15.1 and 4.5 cm, respectively. The periosteum intactness was maintained in 18 (72%) limbs. At 6 months follow-up, regeneration of fibula was present in 15 (60%) limbs. The postharvest-acquired ankle valgus was present in five limbs (24%). There was almost 2.5 times increased likelihood of nonregeneration, if periosteum was breached. The odds ratio for nonregeneration versus regeneration to the development of ankle valgus stood at 12 ( P = 0.0483). Periosteal breach increased the odds of nonregeneration of harvested fibula. The length of harvested segment did not appear to have significant influence on regeneration nor did distal segment on ankle valgus. The nonregeneration of fibula, however, made the limb prone to ankle valgus.

Improved distribution of leg forces after fibular resection and synostosis

Purpose

Genu varum- a common symptom in achondroplasia- may lead to ankle valgus in children. Ankle valgus may be mitigated by tibiofibular synostosis, but this is not always the case. The mechanical environment around the growth plates plays an important role in ankle valgus. The purpose of this project is 1) to determine the strain through the distal fibular growth plate before and after tibiofibular synostosis, and 2) postulate whether the change in strain affects ankle valgus. This project measured the distal fibular strain in a porcine hind leg model.

Methods

The lower legs of seven pigs were removed, instrumented with strain gauges, and loaded compressively in a material testing machine. Loads were applied at three phases: 1) the intact leg, 2) leg with fibula resected, and 3) leg with fibula resected and tibiofibular synostosis. Mean strains were compared between phases using a mixed affect model. The significance level was adjusted for multiple comparisons using the Bonferroni method.

Results

Phase 1, intact leg, had the highest strain value at 1247.9μɛ. In phase 2, the mean strain was 106.2μɛ. In phase 3, the compressive mean strain dropped to 477.4μɛ, which is 38% of the strain in phase 1. Standard error was 86.8μɛ; p < 0.001.

Conclusion

Results indicate that more of the force through the leg is transmitted through the tibia after fibular resection and tibiofibular synostosis, which improves the balance of forces through the leg.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00480-0.

Congenital Pseudarthrosis of the Fibula: Controlling Ankle Valgus in a Heterogenous Condition

BACKGROUND

Congenital pseudarthrosis of the fibula (CPF) is a rare disorder characterized by a deficiency in the continuity of the fibula and can lead to progressive ankle valgus malalignment. An existing classification system for CPF is imperfect and may contribute to heterogeneity in reporting and discrepancy of outcomes in the literature.

METHODS

Fifteen patients with CPF treated at our institution between 1995 and 2017 were retrospectively identified. Only patients with dysplasia leading to spontaneous fracture or pseudarthrosis were included in this series. The median age at presentation was 2.5 years (range: 3 mo to 13.4 y). The median duration of follow-up from the initial presentation was 11.8 years (range: 2.0 to 24 y). Chart review and serial radiographs were analyzed to assess natural history and outcomes following surgery.

RESULTS

The coexistence of tibial dysplasia in CPF is very common. Patients were classified into 3 groups based on the degree of tibial involvement-group 1: no evidence of tibial dysplasia, group 2: mild tibial dysplasia, and group 3: significant tibial dysplasia. Age at presentation and age at which fibular fracture occurred were progressively younger with a greater degree of tibial involvement (P<0.05). In the absence of surgical intervention, group 1 patients did not undergo progressive ankle valgus (defined as the valgus change in tibiotalar angle by ≥4 degrees), whereas all patients in groups 2 and 3 did (P<0.001). Fibular osteosynthesis was performed in 6 patients, with union seen only in group 1 patients. Ten patients underwent distal tibiofibular fusion, with no cases of nonunion seen. Distal tibiofibular fusion with or without medial distal tibial hemiepiphysiodesis halted the progression of ankle valgus in 8 of the 10 patients. Further progression of ankle valgus occurred only in patients who did not undergo concurrent medial distal tibial hemiepiphysiodesis and with considerable wedging of the distal tibial epiphysis at the time of fusion.

CONCLUSIONS

Tibial dysplasia and CPF are intimately related. Grouping patients on this basis may help guide natural history and treatment and may explain discrepancies in findings in the literature. Fibular osteosynthesis, distal tibiofibular fusion, and medial distal tibial hemiepiphysiodesis may all have an important role in the treatment of CPF.

LEVEL OF EVIDENCE

Level IV-case series.

Management of Congenital Pseudoarthrosis of the Tibia and Fibula

PURPOSE OF REVIEW

Congenital pseudoarthrosis of the tibia and fibula are rare conditions that share common treatment strategies. The purpose of this review is to provide an overview of the recent developments in treatments for both conditions.

RECENT FINDINGS

Recent literature has focused on the use of BMP and on gait analysis as a tool for measuring long-term functional outcomes. Recent study has indicated rhBMP-2 may shorten the time to initial healing of pseudoarthroses, but not guarantee bony union. Children with initial fractures before the age of four have been shown to have long-term gait outcomes that may be ultimately comparable to children with prostheses. Both congenital pseudoarthrosis of the tibia and fibula are challenging conditions to treat, which require comprehensive approaches to account for both the biological and mechanical components of the conditions.