Bilateral congenital pseudoarthrosis of the tibia: A case report and literature review

Abstract

Congenital Pseudoarthrosis of the Tibia (CPT) is a rare disease with an incidence of one in 190,000 live births. Bilateral presentation is extremely rare, and very few case reports of bilateral CPT are mentioned worldwide. Bilateral CPT has added challenges to treatment. We here present a case report of a 4-year-old girl with bilateral CPT with Neurofibromatosis type-1 (NF-1) managed with ‘4 in 1 osteosynthesis’ surgery of the right leg.

1. Introduction

Congenital Pseudoarthrosis of the Tibia (CPT) presents with anterolateral bowing of the tibia. CPT is a rare presentation with 1 in 190,000 live births.¹ Almost all cases are unilateral with slight left-sided predominance. Only very few case reports of bilateral CPT have been mentioned worldwide (Table 1). Up to 55 % cases of CPT are associated with Neurofibromatosis type 1 (NF-1), and 15 % are associated with Fibrous dysplasia (FD).² Also, as most bilateral cases are associated with NF-1, they respond poorly to Bone Morphogenic Protein (BMP) treatment.³

Table 1.

List of publications with bilateral congenital pseudoarthrosis of tibia (CPT). ∗FD= Fibrous dysplasia; NF= Neurofibromatosis.

Author/year	Study type	Total number of cases in study	Number of bilateral cases	Associated condition (NF/FD)	Management
S. B.BERKSHIRE et al., 1970	Case Report	1	1	Yes (FD)	Not mentioned
D Paley et al., 1992	Single Centre Retrospective Study	16	1	Not Mentioned	Ilizarov
Kim et al., 2002	Signle Centre	14	1	No	Intra medullary (IM) fixation and autogenous bone grafting
Laurent Mathieu et al., 2008	Single Centre Retrospective Study	10	1	Yes (NF)	Combined Ilizarov fixator with IM nail
Ste'phanie Pannier et al., 2013	Single Centre Retrospective Study	5	1	Yes (NF)	Induced membrane technique
Dmitry Y. Borzunov et al., 2016	Single Centre Retrospective Study	28	1	Yes (NF)	Ilizarov
A Yan et al., 2018	Single Centre Retrospective Study	40	3	Not Mentioned	4 in 1 osteosynthesis and combined surgical techniques
Margarida Miranda et al., 2019	Case Report	1	1	Absent	Opening wedge tibial osteotomy with fibular grafting and K- Wire fixation.
MOHANKUMAR, 2020	Case Report	1	1	Absent	Excision of pseudoarthrosis, fixation with reconstruction plate and iliac bone grafting
Ari B	Case report	1	1	Yes (NF)	Excision of pseudoarthrosis and fibula grafting with Ilizarov fixation
Zhou Yijun et al., 2022	Single Centre Retrospective Study	514	11	Not Mentioned	Not Mentioned
Our Case	Case report		1	Yes (NF)	4 in 1 osteosynthesis

The bilateral CPT cases may be more challenging compared to unilateral cases, as the surgeon needs to tackle 2 bony sites which are refusing to unite.

Here we present a case report of a 4-year-old female with bilateral CPT and NF-1. We have also explored previous literature on CPT mentioning bilateral presentation.

2. Case report

A 4-year-old girl presented with complaints of bilateral lower limb deformity and difficulty in walking. The parents noticed the bowing of both legs since birth. At the age of 9 months, when she started to stand and walk, she got a fracture in her left leg. At the age of 1.5 years, she sustained fracture of right leg. No relief was achieved after multiple plaster casting applications on both legs. To prevent further damage, long clamshell orthosis was advised to the patient while walking (Fig. 1A). The patient had no history of surgical intervention.

Fig. 1.

Clinical picture of the patient showing A- Patient standing with clamshell brace; B,C-multiple large café au lait spots over limb and trunk; D,E− Picture of limb showing bowing and deformity.

None of the other family members had a history suggestive of NF-1. On examination of the child, we noticed multiple coffee-brown spots on the limbs and trunk along with two bony lesions of the tibia, suggestive of NF-1 (Fig. 1B and C). Ophthalmology evaluation was clear. On genetic testing, the NF-1 gene was positive (performed on parental request).

Local examination revealed deformities and abnormal painless mobility with anterolateral bowing in both legs. Both lower limb lengths were comparable (Fig. 1D and E). The patient was able to walk with the support and clamshell orthoses.

Radiographs showed bilateral CPT with atrophic tibial bone ends, with pseudoarthrosis of left fibula (Fig. 2-A, B, C).

Fig. 2.

Pre-operative X-ray showing pseudoarthrosis of bilateral tibia. A- Bilateral lower limb scanogram; B- Left leg x-ray; C- Right leg x-ray. To note there is left side fibula pseudoarthrosis but on the right side, only fibula bowing is present.

After a complete assessment, a diagnosis of bilateral congenital pseudoarthrosis of the tibia (CPT) with NF-1 was made. After counseling and explaining the prognosis, ‘4 IN 1 OSTEOSYNTHESIS’ was planned for the right side as 1st stage.⁴ The zoledronic acid injection was administered 6 weeks before surgery. Meticulous dissection of the neurovascular bundle and exposure of fibrous hamartoma was done and then complete resection of the hamartoma along with sclerotic tips of fragments was completed. The medullary canal of the tibia was opened. Under fluoroscopic control, a k-wire carefully drilled in a retrograde manner in the tibia passing through the calcaneum, talus, and tibia after docking in of tibial bone ends. For rotational stability, Tibia was additionally stabilised with a 2.8 mm recon plate. As the fibula curve was high, it was not possible to pass k wire through it. Therefore, fibula fixation was not done. All four bone ends of the tibia and fibula were wrapped in a sleeve of periosteum taken from the iliac inner table and packed with bone grafts for the cross union. Cortical sleeves from the distal femur were placed anteriorly to give a circumferential bone graft cover (Fig. 3). As the bone graft from the iliac crest was scant, the opposite distal femur was used to harvest the bone graft in addition to the iliac. The surgical and postsurgical periods were uneventful. As a postoperative protocol, the above knee cast was given for the first 3 months post-surgery, after which a clamshell was given for splinting. Zoledronate was injected 3 months post-surgery. The latest radiograph was obtained at 3 months and at 5months after surgery and showed a good amount of callus formation and uniting all 4 bone ends (Fig. 4 A, B, and C). The patient is currently ambulatory and being followed up for long-term outcomes.

Fig. 3.

Schematic diagram showing graft placement in our surgery. 1 = tibia, 2 = inner table from iliac bone, 3 = cancellous bone grafts, 4 = fibula, 5 = cortical cone from contralateral distal femur.

Fig. 4.

Post-operative x-ray of the right leg. A-on post-operative day 1; B- at 3 months post-surgery; C- at 5 months post-surgery showing good progress and cross-union.

3. Discussion

CPT is a rare condition, with almost all cases unilateral. In the literature search, we found only a limited number of articles on bilateral CPT and only one case report from India (table no 1)-⁵,⁶,⁷,⁸,.⁹ Treatment of CPT is challenging, and it is more so in bilateral cases as it hinders ambulation, with no support from other healthy leg as in the case of unilateral CPT. Therefore, the risk of fracture, non-union, and symptomatic clinical presentation in bilateral CPT seems to be higher than in unilateral CPT. Also due to the involvement of other tibia, one source of bone graft, which is easily available in unilateral CPT is not available in bilateral cases.

We performed surgery on right leg. Intra-operatively, due to scanty graft from iliac crest, contralateral distal femur was utilized for graft harvest. There are literature reports of using allograft as prophylactic procedure in unilateral CPT but its use in established non-union is not described.¹⁰

We found no article focusing specifically on the management of bilateral CPT. However, considering the literature-proven success of ‘4-in-1 osteosynthesis’ in unilateral CPT, it seems logical to perform & expect a fair outcome of the same procedure in bilateral cases, albeit with some challenges. Our case shows good union with return to ambulation in a short follow-up. However, we accept that a longer follow-up is preferable for CPT, ideally up to skeletal maturity. Surgery of bilateral limbs in one stage or one after another, the ideal gap period between two surgeries, the period of immobilization, the source of bone graft, and the role of BMP or Zoledronic acid – all are debatable. Also, the long-term prognosis of unilateral vs bilateral CPT is not well described. All these issues make treatment of bilateral CPT more challenging. Proper counseling of parents, meticulous planning, and expertise for such scenarios become more important in bilateral CPT cases.

4. Conclusion

Bilateral CPT is a rare presentation with only a few case reports worldwide. Most of these patients have associated conditions of fibrous dysplasia or neurofibromatosis. Bilateral presentation adds more challenges to the treatment of CPT. ‘4-in-1 osteosynthesis’ procedure may be performed similar to unilateral cases. Literature is lacking on the management and long-term results of bilateral CPT.

Conflict of interest

The authors declare that they have no conflict of interest.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.