Advancing care for congenital pseudoarthrosis: A case series highlighting the combined use of an intramedullary device with either Ilizarov’s fixators or plating for the treatment of congenital pseudoarthrosis

INTRODUCTION

Congenital pseudarthrosis of the tibia (CPT) is a bone defect in which non-union occurs in a dysplastic segment of the tibial diaphysis following a fracture at the same site. In most cases, CPT has been linked to neurofibromatosis type 1 (NF-1); however, no signs of neurofibromatosis tissue at the site of CPT have been found.^[1] CPT is a rare condition with an incidence of 1:53,000 in Norway^[2] ranging from 1:28,544 to 1:190,000 live births, according to two other studies conducted in Finland and Denmark, respectively.^[3,4] CPT is usually preceded by bowing, where the risk of fracture and consequent pseudoarthrosis is higher with progressive bowing.^[5]

Non-operative management should be started immediately once tibial bowing is observed in patients with a higher chance of CPT development using ankle-foot orthosis (AFO) and knee-AFO is recommended as non-operative measures depending on the patient’s age to extend the pre-operative period and minimize complications.^[6]

Once a fracture occurs through a susceptible bone and pseudoarthrosis is formed, spontaneous healing is unexpected. Therefore, surgical intervention is essential for healing.^[6] Healing potential through pseudoarthrosis of the tibia is challenging. Hence, multiple surgical options with different healing rates have been described in the literature.^[7] For the last few decades, there has been much discussion on which surgical treatment is optimal to achieve bone union.^[7]

This study aimed to compare the outcomes of using intramedullary nailing with either Ilizarove’s fixator or plating as a treatment method for CPT to other treatment methods described in the literature.

CASE SERIES

This study was approved by the Institutional Review Board (IRB). This case series study included nine patients who presented to the Pediatric Orthopedic clinic with CPT from 2018 to 2021. All patients were previously diagnosed with NF-1 by pediatric genetics and presented with unilateral CPT. The minimum follow-up duration was 12 months.

RESULTS

Nine patients were previously diagnosed with NF-1 in the Pediatric Orthopedic Clinic for CPT. Male sex was predominant 5/9 (55.6%) and the mean age of the affected population at the index surgery was 6.11 ± 3.41. The mean follow-up duration after surgery was 17.33 months, with a minimum of 12 months. The characteristics of each patient are shown in Table 1.

All patients underwent resection of the pseudoarthrotic segment, Fassier-Duval (FD) nailing, cross-tibia-fibula union, and iliac autograft. The fixation was supplemented with an Ilizarov external fixator in five patients [Figure 1], and the plate was used in four patients [Figure 2]. Most patients (88.9%) achieved a union of 4 cortices and cross-union with a mean of 4.88 ± 1.55 months from the surgery. The patient who did not achieve union had an infection requiring multiple surgical debridements, and healing was not achieved until the date of writing this paper. There were no reported refractures until the last visit of each patient to the clinic. The Chi-squared test showed no statistically significant difference between the age at the first surgery and bone union. The type of fixation was not significantly associated with the union rate.

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Figure 1:

Radiological images of a patient with congenital pseudoarthrosis of the tibia who was treated with Fassier-Duval nail and Ilizarov fixator, (a) shows a pre-operative radiograph, (b) was taken 1 day postoperatively, and (c) shows complete union after 4 months from surgery.

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Figure 2:

Radiological images of a patient with congenital pseudoarthrosis of the tibia who was treated with Fassier-Duval nail and tibial plating. (a) shows a pre-operative radiograph, (b) was taken 1 day postoperatively, and (c) shows complete union after 4 months from surgery.

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There were no reported immediate post-operative complications or donor-site morbidities. Superficial pin site infection at either half pin or wire entry site was noted in some patients. All patients who demonstrated pin site infection during follow-up were treated with oral antibiotics and daily dressing using wet gauze with normal saline covered by dry gauze.

The mean proximal and distal tibial angles were 91.26° and 104.94°, respectively. Five patients had proximal tibial valgus from the last visit radiographs, and most patients (6 out of 9) demonstrated ankle valgus. Three patients with ankle valgus required distal tibial medial epiphysiodesis. Significant LLD was reported in four patients, with a mean of 3.25 cm. The patient and his family were aware that the patient would require future lengthening surgeries.

At the last visit to the clinic, all patients could bear weight without pain, except for one patient with non-union. Knee stiffness was not reported in any patient, but ankle stiffness was reported in four patients. All the patients were instructed to use a clamshell orthosis until skeletal maturity.

DISCUSSION

CPT is a challenging disease that can present but not exclusively to patients with NF.^[8] Achieving union and preserving the limb from refracture, LLD, and residual malalignment is difficult.^[9] Most of the patients were exposed to many surgeries aiming to achieve union, which can complicate things, ending with large bone defects.^[8,10] The optimal goal of CPT treatment is to achieve a united tibia, well-aligned leg, and functional limb without significant limb length discrepancy.^[11]

Different surgical approaches are currently being used to achieve union and decrease the risk of complications. Most surgical techniques follow the same principles, including complete excision of pseudoarthrosis, rigid fixation, and bone grafting. The achievement of favorable outcomes has improved dramatically in recent years. Union has been achieved in 70% of cases after a single intervention, and amputation is rarely needed nowadays.^[12] The traditional surgical method worldwide is the surgical excision of diseased segments and intramedullary rodding or circular external fixation using the Ilizarov frame. In a study by Akaro et al.,^[5] intramedullary rodding or circular external fixation using the Ilizarov frame was used in 54.7% and 18.8% of cases, respectively. Of 54.7% who underwent intramedullary rodding, approximately 8.3% had a solid tibial union that used no external support or splint. In another study, the Charnley-Williams procedure was used, and full weight-bearing and unequivocal union was achieved in 48% of cases.^[8] Plating as a fixation method is uncommon; according to a multicenter study that involved 73 patients in 32 different hospitals, plating and bone grafting were used in 5 patients, of whom 3 achieved union.^[13] While the research field in CPT is growing, Paley described the cross-union method by creating a tunnel in the interosseous membrane between the tibia and fibula.^[14] The union rate using this method reached 100% without any refracture cases.^[14] This method has accelerated research to assess the efficacy of this technique. Shannon et al. found that using Paley’s technique, dual fixation and cross-union reached 100% union.^[14] An “Eiffel Tower” double titanium elastic nailing and telescopic intramedullary rod have been tried as a method of fixation in combined surgical management for CPT, which has the advantage of less injury to the metaphysis and facilitating normal ankle functions.^[11,15] A combination of intramedullary nailing and Ilizarov fixation has also been tried, showing higher effectiveness in treating CPT^[9,10] and achieving initial union in 89.2% of patients with Crawford type-4 CPT.^[16] Liu et al. showed that telescoping nails (FD nails), Ilizarov fixators, cross-union, and iliac bone grating had achieved a 100% union rate without refracture.^[15] In patients who demonstrated good bone stock at the pseudoarthrosis site and to avoid Ilizarov fixator complications, a locking plate was used instead of an Ilizarov fixator in combination with a telescoping nail, which showed a similar union rate.^[17]

Different techniques for bone grafting aiming to achieve union have been tried. In one study, an autogenous cortical bone graft was wrapped around the osteotomy site where the bone union was observed in 89.2% of patients.^[10] A similar union rate was achieved in 88.9% of patients where an autogenous periosteal sleeve bone graft was used to wrap the osteotomy site in our study, given that an autogenous cancellous bone graft was placed in the osteotomy site in both procedures.

Complications for surgical management of CPT, such as refracture and LLD, are common, and a study showed that refracture occurred in nearly half of the patients who underwent intramedullary nailing and Ilizarov’s fixation technique. Refracture also occurred in 9 of the 52 patients who underwent vascularized fibular transfer.^[12] With the Charnley-Williams method, persistent non-union or refracture was observed in only 3 of the 21 patients.^[8] Two other studies reported that LLD was the predominant complication.^[5,6]

Limb alignment should be preserved during treatment to avoid refracture.^[8] In addition, an intramedullary nail device should be used as an internal splint.^[8] Various surgical methods have been described in the literature and are debatable for treating CPT.^[11] Historically, amputation was the treatment of choice for CPT patients because of the high rate of non-union to avoid repeated surgeries^[18] and is now reserved for cases where failure of union occurred after multiple surgeries or in cases of significant LLD in a nonfunctional limb.^[18] All the following surgical options are supplemented by resection of the pseudoarthrosis segment and bone graft use. The Ilizarov fixator alone provides the advantage of compressing the osteotomy site, which can help achieve union and allow the limb to be aligned properly during the healing phase.^[16] The drawback of this method is risking refracture in almost 50% of patients after the hardware removal.^[16] An intramedullary rod, or William’s rod, spans the ankle joint using a rod to provide further rigidity to the construct.^[15] This technique increases the risk of ankle stiffness, but the union rate previously reported in this technique alone reached 50%.^[8,15] Telescoping nails, where nails slide over each other during the growth of the long bone, are designed to avoid spanning ankle joints.^[15] The disadvantage of this construct is that it might require exchange if the overlap between both parts of the nail is small, which might be separated during bone growth.^[15]

Zhu et al. found that the union rate could reach 90% with a refracture rate of 26% by combining the intramedullary rod and Ilizarov fixator.^[16] The authors’ technique was tested in a small series of patients for mid-term outcomes. The technique includes resection of the pseudoarthrosis segment, telescoping nail insertion, and iliac bone grafting supplemented with an Ilizarov fixator or locked plate, demonstrating an 88.9% union rate without refracture from the mid-term outcome. Union was encountered in one case due to deep infection, which required multiple procedures to eradicate the infection. Akaro et al. showed that patients who underwent index surgery before the age of 3 years had the worst outcomes.^[5] This study did not find an association between age at initial surgery and the final outcome.

LLD is a well-recognized complication of CPT treatment. Nicolaou et al. demonstrated LLD with a mean of 2.5 cm using intramedullary rodding and Ilizarov’s fixation in 11 patients.^[19] In addition, other studies have evaluated the amount of LLD after Ilizarov’s fixation and intramedullary nailing, which showed a mean of 3.34 cm and 1.7 cm, respectively.^[9,11] In line with previous studies, LLD in our study was observed in 4 patients, of whom 3 were treated with intramedullary nailing and Ilizarov’s fixator. These results indicate a higher risk of LLD in patients with intramedullary nailing and Ilizarov’s fixator compared to intramedullary nailing and tibial plating as a fixation method. A significant LLD >2 cm requires further surgical procedures in the future for lengthening.

In another study, pin-site infections were as high as 23.5%.^[11] In contrast to our study and that of Eamsobhana et al., pin-site infection was a minor complication.^[9] In line with previous studies, pin-site infection was successfully treated in all patients using regular dressing and oral antibiotics.^[9,11,16,20] In previous studies, the incidence of deep infection that required surgical debridement was 5.9% and 11.1%, respectively, in which Ilizarov’s fixator with intramedullary nailing was used as a fixation method.^[11,21] In contrast, we had one patient with a deep infection in which intramedullary nailing and tibial plating were used. Ilizarov’s fixator and intramedullary nailing were used in which pin-site infection was observed only. Our study’s low incidence of deep infection could be attributed to the early recognition of pin-site infection and effective treatment to prevent further spread and subsequent devastating outcomes.

Yalikun et al. reported an incidence of proximal tibial valgus deformity and ankle valgus deformity of 22.2% and 38.9%, respectively.^[20] Proximal tibial valgus deformity was seen in five of our patients; 3 of them underwent Ilizarov’s fixation with intramedullary nailing as a fixation method, and ankle valgus deformity was equally seen in three patients in both groups. Weight-bearing was achieved in all patients except for one in whom non-union occurred due to deep infection. In general, the final outcome was similar in both techniques in terms of achieving union and incidence of complications.

One important factor in decreasing the risk of refracture is using a brace postoperatively. In our study, a brace was applied to all patients at 3-month follow-up, and subsequently, refracture was not observed. This finding was in accordance with those of other studies that highlighted the role of postoperative orthosis in decreasing the risk of refracture.^[7,8]

CONCLUSION

Patients who underwent intramedullary nailing in conjugation with Ilizarov’s fixator or plating to treat CPT and cross-union have achieved excellent union rates with no refracture in mid-term follow-up. A deep infection was noticed in one case, which was managed surgically with debridement. Residual deformities in the patient have been noticed and will require corrective surgery.